Patented May 6, 1952 2,595,952

UNITED STATES PATENT OFFICE 2,595,952 POLY WINYLACETATE EMULSON CONTAIN ING A POLYALKYLENE GLYCOL Walter G. Kunze and Raymond Bertram Evans, Catonsville, Md., assignors to Le Page's Inc., Gloucester, Mass., a corporation of Massachu setts No Drawing. Application April 6, 1950, Serial No. 154,421. 7 Claims. (C . 260-29.6) 1. 2 This invention relates to emulsions of polymerS toluene and peroxides. In most instances it was which are suitable for use as coatings and as required that the substances be added to the adhesives. It is particularly concerned with Such polymer emulsion immediately prior to use as the an emulsion of polymers which is capable of resulting compositions were unstable and certain providing a water-resistant bond or coating and of the substances resulted in a progressive in which at the same time retains the stability, crease in the viscosity of the emulsion until a gel fluidity and the various other physical properties Was formed. Gelling rendered the composition of such an emulsion which make it particularly unfit for use in adhesive applicator machines useful as a coating or adhesive. Operated at high speed. Additionally, the modi The use of melts and solutions of Water in 0. fication effected by some of these substances did soluble artificial resins in the coating and adhe not result in a substantial improvement in the sive art has been supplanted to a large extent by Water-resistance of the coating or film deposited emulsions of such resins, particularly polyvinyl from the emulsion, and often imparted unde acetate emulsions, due to the improved ease, Sirable color and foaming characteristics to the economy and safety with Which aqueous emul emulsion. sions of the resin may be employed. On the other Where thermo-plastic polymeric material has hand, the usefulness of water insoluble polymer been employed, it has been suggested that the emulsions has been limited by the characteristic Water-resistance of the coating or bond deposited lack of water-resistance of the coatings and from an emulsion of the material can be improved bonds deposited therefrom at room temperature 20 by heating the coating or bond sufficiently to and the tendency of such coatings and bonds to cause coalescence of the material into a homoge re-emulsify or disintegrate when subsequently neous mass. This procedure is obviously not suit brought into contact with water during the course able where the emulsion is employed as a quick or normal use of the object or article to which setting adhesive in high-speed mechanical ap they have been applied. 25 plicators, and in any event the drying and heating This lack of water-resistance has been con Suggested is often impractical. sidered innate in the coatings and films deposited A further suggestion directed to retaining the from such polymer emulsions inasmuch as Water advantages of working with the polymers in an Soluble emulsifying and bodying agentS are em aqueous medium and at the same time avoiding ployed necessarily to establish and Stabilize the 30 the inherent disadvantages of Water-sensitivity emulsion. These agents are apparently carried of the coatings or films deposited therefrom re into the film or bond deposited from the emulsion quired dispersing the polymer as extremely small upon application of the emulsion to a Surface, particles. The coatings or films deposited from and actively exhibit the emulsifying effect on the Such emulsions do exhibit a satisfactory water polymer comprising the body of the coating or resistance but due to the fine particle size which film and cause its redispersion when the Surface imparts the water-resistance, the emulsions do is brought into contact With Water. not have the tack necessary to make them useful Warious proposals have been made to obviate as quick-Setting adhesives. the water-Sensitivity of the coating or bond de It is an object of this invention to provide a posited from Such emulsions, but in general these 40 COrin position comprising an aqueous emulsion of proposals have been directed to modifying emull *a polymer, particularly a polymer of vinyl ace Sions of Such polymers which have been prepared tate, alone or in combination with Small quanti in a specific manner, or require treating the emul ties of other isnooners, which is stable through Sion with certain diluents immediately prior to its Out long periods of Storage, and Which When application due to the recognized tendency of employed as a coating or as an adhesive will de the Suggested diluents to either break or gel the posit a coating or bond which is highly water emulsion shortly after the addition of the diluent. resistant. A further object of the invention is Prior to the instant invention, for example, a to provide a process which is generally applicable Common expedient for increasing the water to modify einusions of polymers, particularly resistance of a coating or film deposited from a 50 polyvinyl acetate, which have been polymerized Water-insoluble polymer emulsion included the to different extends, or in different manners, addition of a quantity of one or more substances aid Which include various combinations of plas Such as dimethylol urea, trimethylol melamine, ticizers and other diluents commonly employed certain chromium salts, strong acids or highly to develop favored characteristics in the films or l'eactive aldehydes Such as glyoxal, certain resins, 55 coating deposited from such emulsions. 2,595,952 3 4. We have discovered that the water-resistance and above are effective. The upper limit of of coatings or bonds deposited from an aqueous molecular weight of these polymers at which the emulsion of polymers, particularly polyvinyl molecule is dominated by the non-polar residue, acetate emulsions, which are formulated, or the ether chains, appears to be in the vicinity of modified, to have a tackiness rendering then about 1,000. It was noted, for example, that suitable for use as quick-setting adhesives, can poly propylene glycol 1025 was not effective, be established by additions of one or more of a whereas the polymer glycols having a lesser no certain group of Organic compounds Within Spe lecular weight were very active. It was observed cific limits. These active compounds are char in the case of the polyethylene glycols that poly terized by a particular balance between the parts 10 merization to a molecular weight which marked of the monomeric molecule, one part of Which the limit of activity as an active compound cor is hydrophilic or polar in nature, and the other responded with the extent of polymerization at part of which is hydrophobic or non-polar. The which the compound showed a marked reduc effectiveness of the compounds in producing tion in water solubility. Apparently, the pre water-resistance in the coatings or bonds de dominance of the polar residue at this point posited from such emulsions is apparently due causes both effects. to the presence of both the polar and non-polar Particularly good results were obtained with groups within the molecule in the prescribed dipropylene-glycol, molecular weight 134, tri balance. As a class, these active compounds ex ethylene glycol, molecular weight 150, poly-pro hibit solubility, to various extents, in both Water pylene-glycol, molecular weight 450. and in organic solvents such as mineral Spirits, The preferred range of quantities of one or petroleum ether, toluene, castor oil, etc. This more of the active compounds by weight with re solubility in both water and organic Solvents ap Spect to the solid content of the polyvinyl acetate parently is due to the dual hydrophilic-hydro emulsion has been found to be between about phobic nature of the compound. As it has been 25 four to twenty-five per cent, the optimum amount generally recognized that the presence of Water in a particular instance depending upon the in Soluble emulsifiers carried into the bonds and itial Water-resistance characteristics of the start coatings deposited from emulsions of water-in ing material emulsion, the amount of plasticizers soluble polymers may later cause redispersion employed, the age of the starting material emul and disintegration of the bonds and coatings, it 30 sion, and the rate at which the composition is was particularly surprising, to find that incorpo formulated. rating into the emulsion additional compounds The physical properties of a polyvinyl acetate which are water-soluble themselves will nullify emulsion Such as the viscosity of the emulsion, the effect of the water-soluble emulsifiers and and the tensile strength, flexibility and heat seal thereby impart water-resistance to the coatings ing temperature of the film or bond deposited and films deposited from such emulsions. from the emulsion are determined in a large part For present purposes a polar or hydrophilic by the degree of polymerization of the vinyl ace group or radical may be considered to be one tate monomer. A higher degree of polymeriza which has a strong affinity for Water and which tion results in increased bond strength, a higher When combined in compounds in which it is the heat sealing temperature and a somewhat higher dominant functional group Will cause the re initial water-resistance, which is, however, consid Sulting compound to be immiscible, or miscible erably less than required commercially for a to a limited extent, in oil-type solvents. A non Water-resistant coating or bond. Alesser quantity polar or hydrophobic group, on the other hand, of active compounds is necessary to impart the de may be considered to be one which has slight sired water-resistance to the deposited coatings affinity for water and a strong affinity for oil or bonds when the relatively greater water-re type Solvents. In general, the hydroxyl group Sistant emulsions are employed as a starting ma displays the characteristics of a Suitable polar terial. group. Within defined limits ether chains such For present purposes the polyvinyl acetate as those present in the polyglycols may exhibit Starting material emulsions having sufficient tack hydrophobic characteristics which will result in to be useful as quick-setting adhesives may be the desired Water-resistance when a compound classified in three groups according to their initial comprising Such a chain combined with hydroxyl Water-resistance although in each instance the groups is employed with emulsions of polyvinyl Water-resistance is negligible from the stand acetate as hereinafter specified. 5 5 point of minimum commercial requirements. We have found that the polymeric glycols Such emulsions generally contain about 50-60% having a, Inolecular weight of 134 inclusive to polyvinyl acetate by weight, and a bond produced about 1,000 are generally active in producing by the respective emulsions between two sheets water-resistance in the films or coatings de of mildly calendered white Sulphite paper will posited from polyvinyl acetate emulsion. The 60 Open up after 24 hours immersion in water at polymers of these compounds generally contain about 25° C. certain amounts of the monomeric material Such polyvinyl acetate emulsions, which in which is polynerized to different extents, so that clude the commercially available emulsions known the molecular weight specified refers to an aver as Elvacet No. 80-900, Elvacet 81-900, Gelva, S-50, age Weight. Polyco 117H, Polyco 289 and Polyco 117SS pro Ethylene glycol, diethylene glycol, and propy duce bonds which show practically no Water-re lene glycol, having 2, 4 and 3 carbon atom chains, sistance on immersion. respectively, combined in their molecules with The physical characteristics of the commer two hydroxyl groups are too hydrophilic to be cially available polyvinyl acetate emulsions iden generally effective with all types of polyvinyl 70 tified above may also vary to some extent as a acetate emulsion. It has been observed, how result of the emulsifiers and bodying agents em ever, that polymerization of the monomeric ployed in producing the emulsions, and also as inolecules Will mask to a large extent the hydro a result of particular plasticizers employed. In philic nature of these compounds, and the poly general, however, the variations which tend to meric forms having a molecular weight of 134 75 increase the relative initial water-resistance of 2,595,952 the starting material emulsions lessen the quan least effect on other physical characteristics of tity of the active compounds required to effect the composition when a total of from 12-17% of Complete Water-resistance. active compound or compounds by weight of solids The amounts of active compound required to in the starting material emulsion are employed. produce maximum Water-resistance in a par 5. It has been found that the effectiveness of a ticular emulsion also varies with the quantity and given amount of active compound can be en the nature of the plasticizers, extenders, or other hanced by diluting the composition with water to diluents which may be used to develop desired reduce the solid content thereof, to between characteristics of fluidity or tackiness in the 40-50% after the active compound has been emulsion, or of flexibility, hardness, etc. in the 10 thoroughly mixed with the starting material coating or film deposited from the ennulsion. In emulsion. Some of the numerous possibilities general, it has been found that the insoluble which exist informulating a water-resistant com type of plasticizers and resins in common use in position within the operable limitations specified crease the effectiveness of the active compounds, above are illustrated in the following examples. and that a lesser quantity of active compound is 15 The addition of the active compound to the necessary to produce complete water-resistance starting material emulsion may result in a sub when such plasticizers are also present in the stantial increase in the viscosity of the emulsion emulsion. It should be noted, however, that in to form a cohesive mass unless the active com each instance the emulsion containing the plasti pound is added slowly with continuous agitation. cizers and various other diluents was not ini 20. In Some instances rapid addition of the active tially Water-resistant and that the addition of compound resultS in localized precipitation of the the active compound Was necessary to effect any emulsion. The largest part of the increased co Satisfactory Water-resistance, although as re hesiveness and viscosity of the emulsion caused lated above, a lesser amount is necessary when by addition of the active compound at a suitable insoluble plasticizers are also present. 25 rate disappears on agitation, or when the treated This enhancing effect of the insoluble plasti emulsion is permitted to stand for a short period cizers was particularly observed with respect to following the addition of the active compound. dimethyl phthalate, dibutyl phthalate, chlori In all of the following examples the composi nated diphenyls, methyl abiatate and tributyl tion was prepared by stirring the starting mate phosphate, and appears to be characteristic of 30 rial emulsion with a high-speed mixer con other common plasticizers such as di-carbitol tinuously during the addition of the active com phthalate, dibutoxyglycol phthalate, dimethoxy pound thereto. The active compound was in glycol phthalate, butyl phthalyl glycolate, methyl troduced into the emulsion at the rate of about phthalyl ethyl glycolate, triglycol di-2-ethyl 3% of the total weight of the active compound butyrate, triglycol di-2-ethylhexoate, tricresyl 35 per minute. The formulation can be carried out phosphate and triphenyl phosphate. at normal ambient temperatures. On the other hand, the presence of a small Each of the tacky starting material polyvinyl amount of water-soluble thickeners such as poly emulsions was applied as a coating on the surface vinyl alcohol and Sodium carboxymethyl cellulose of a moderately calendered and sized white sul tend to increase the amount of active compound 40 phite paper and as a bond between two such necessary to effect maximum water-resistance. paperS. The films and bonds thus formed were In some instances care must be exercised to allowed to dry for 24 hours at room temperature avoid breaking the emulsion by sudden heating, and were thereafter immersed in water at room or by extended heating above the temperature temperature for 24 hours. Upon removal from specified. The critical temperature will vary, of 45 the Water the wet strength of the paper exceeded course, with the character of the particular start the bond strength in all cases, and the bond rup ing material emulsion employed. tured when the bonded papers were separated. Aging the composition tends to increase the The coatings in each instance had visibly disin water-resistance of the coatings or films deposited tegrated. These starting material emulsions therefrom. 50 were, therefore, considered non-water-resistant, It will be apparent from the foregoing that in and in the subsequent experiments, satisfactory numerable poSSibilities for formulating the in Water-resistance of a film or bond formed from stant water-resistance composition exist, and an emulsion treated with an active compound was that the invention may be practiced to increase considered fully indicated when the strength of the Water-resistance of any particular polyvinyl 55 the bond exceeded the wet strength of the paper acetate emulsion without materially interfering after 24 hours immersion. with the versatility of the Starting material ennul It will be understood that the films and bonds sion. It will be noted, however, that any of the deposited from emulsions of the type here dealt active compounds having the requisite polar-non with comprise the materials found in the emul polar balances in the molecules thereof are effec 60 Sions with the exception of the external water tive in producing water-resistance when used in phase which evaporates upon drying of the films quantities within the range of 4-25% by weight and bonds. of the Solids present in the starting material poly Eacomple 1 vinyl acetate emulsion. A first Sample was prepared by placing 110 The minimum amount of a particular one of 65 grams of a tacky polyvinyl acetate emulsion hav the active compounds depends upon the factors ing about 55% solid content in a container and previously discussed, but in all instances is with stirring it continuously with a high-speed mixer. in the range referred to above. Compositions 25 grams of a rosin emulsion extender (Dresinol having up to 50% by weight of active compounds 42) and 6 grams of dimethyl phthalate plasti With respect to the solid content of the starting 70 cizer were added to the emulsion and the stirring emulsion may be employed, especially where the continued. 2.5 grams of dipropylene glycol were active compound has plasticizing properties which added slowly to this mixture and the stirring con are desirable and the cost of the compound is not tinued until a homogeneous mass was obtained. prohibitive. In most instances, however, the Four additional samples were similarly pre maximum water-resistance is obtained with the 75 pared using, respectively, 3.5 grams, 5 grams, 6 2,595,952 7 8 grams and 9 grams of dipropylene glycol in place same manner as those referred to above With of the 2.5 grams thereof used in preparing the the exception that the dilution of the emulsion first sample. was omitted. These samples Were similarly The Waterproofness of each Sample was tested tested and were also found to deposit Water by applying it as a film and bound to a mildly proof films and bonds calendered and sized white sulphite paper. The Eacample 5 films and bonds were thereafter allowed to dry for 24 hours. They were then immersed in Water Two samples were prepared by adding, re at room temperature for about 24 hours. The spectively, 15 grams and 25 grams of triethylene films remained continuous and intact. The bonds O glycol to a tacky polyvinyl emulsion having a exceeded the wet strength of the paper and re solid content of about 55%. The starting mate mained unbroken. When the bonded paperS Were rial emulsion was stirred continuously during Separated. this addition. Both Samples Were tested for Wa 5 additional sainples were prepared using the terproofness in the manner described in Example same announts of staiting material emulsion and and were found to deposit Waterproof films dipropylene glycol but omitting the extender and bonds. and plasticizer. These samples Were tested in the manner described above and Were also found Eacample 6 to be Waterproof. Five samples Were prepared by adding, re Eacample 2 - 20 spectively, 5, 10, 15, 20 and 25 grams of diethyl ene glycol to 110 grams of a tacky polyvinyl A composition was prepared by placing 110 acetate emulsion having a solid content of about grams of a tacky polyvinyl acetate emulsion 55%. The addition of the diethylene glycol was having about 55% solid content in a container made slowly While the starting material ennul and stirring this continuously while adding 15% sion was stirred constantly With a high-Speed by Weight of the solid content of the emulsion of mixer. Five additional Samples Were prepared polypropylene glycol 1025. A second sample WaS in the same manner and to each of these was prepared in the same manner and 10 grams of added 6 grams of a dimethyl phthalate plas a dimethyl phthalate plasticizer was added to ticizer. All ten samples were tested for Water the second sample. Both samples were tested 30 proofness in the manner described in Example 1. for waterproofness in the manner described in In each instance the films and bonds deposited Example 1. In each instance the film and bond therefrom had disintegrated after the 24 hour had disintegrated after 24 hours immersion. immersion in water. None of the samples de The wet strength of the paper exceeded the posited waterproof films and bonds. strength of the bonds deposited from these San- ; ; It will be apparent that the water-repellent ples and the bond was broken when the bonded compositions formulated according to the instant papers were Separated. invention will considerably extend the usefulneSS Eacample 3 of aqueous emulsions of polyvinyl acetate into the field in which high water-resistance of the 110 grains of a tacky polyvinyl acetate emul 40 bond or coating deposited is necessary and will sion having about 55% solid content was placed find application in bonding or cementing for in a mixing container and stirred with a high cellulosic articles such as paper cups which in the speed mixer. 2 grams of polypropylene glycol course of normal use are exposed to Water and 425 and 10 grains of a dibutyl phthalate plaS for bonding Surfaces of cellulosic material to other ticizer were added to this starting material emul- . Surfaces of a hydrophilic character Such as sion. The stirring was continued until a ho masonry. These compositions are particularly mogeneous mass was obtained. A Second Sam adapted for use as a sizing where water-resistance ple was similarly prepared using 28 grams of of the fabric or the paper to which it is applied polypropylene glycol 425 in place of the 12 grams is required. It may also be employed in the linentioned above. A third sample was formu 50 composition of printing paste, as a finish for iated by adding 15 grams of polyethylene glycol paper, paper-board, or foils and in the manu 425 to 110 grams of the same starting material facture of formed or impregnated goods, as well emulsion. as in distemper paints and the like. All these samples were tested for waterproof Having thus described the invention, what is less in the in anner described and found to be new and desired to be secured by Letters Patent waterproof. 1S Eacample 4 1. A composition comprising a tacky aqueous 110 grams of a tacky polyvinyl acetate having emulsion of polyvinyl acetate and 4 to 50% by a solid content of about 55% Was placed in a Weight of Said acetate of an unsubstituted poly container and stirred continuously with a high 60 alkylene glycol having a molecular weight of 134 speed mixer. 6 granus of a dimethyl phthalate to 000. plasticizer and 5 grams of polyethylene glycol 2. A composition comprising a tacky aqueous 400 were added slowly to the starting material emulsion of polyvinyl acetate, a plasticizer fol' emulsion. Thereafter the emulsion was diluted said acetate, and from 4 to 50% by weight of said with water to bring the solid content thereof to acetate of an unsubstituted polyalkylene glycol about 40% by Weight of the emulsion. A Second having a molecular weight of 134 to 1000. and third Sainple were prepared in the same 3. A composition comprising a tacky aqueous manner using, respectively, 6 and 15 grams of emulsion of polyvinyl acetate, and from 4 to 50% polyethylene glycol 400 in place of the three by weight of Said acetate of a polymeric ethylene grams thereof used in the first sample. The 70 glycol having a molecular weight of 150 to 1000. waterproofness of the films and bonds deposited 4. A composition comprising a tacky a queous from all these Saraples Was tested in the manner emulsion of polyvyinl acetate, and from 4 to 25% described in Example 1, and all were found to be by weight of said acetate of triethylene glycol. Waterproof. 5. A composition comprising a tacky aqueous Three additional samples were prepared in the 75 emulsion of polyvinyl acetate, and from 4 to 25% 2,595,952 10 by weight of said acetate of a polymeric propylene UNITED STATES PATENTS glycol having a molecular weight of 134 to 1000. 6. A composition comprising a tackyaqueous Number Name Date emulsion of polyvinyl acetate, and from 4 to 25% 2,300,074 Strain ------Oct. 27, 1942 by weight of said acetate of di-propylene glycol. 2,444,396 Collins et al. ------June 29, 1948 7. A composition comprising polyvinyl acetate 5 and from 4 to 50% by weight of said acetate of OTHER REFERENCES an unsubstituted polyalkylene glycol having a "Vinylite Resins,' published 1942 by Carbide molecular weight of 134 to 1000. and Carbon Chemicals Corp., page 4. WALTER, G. KUNZE. * , O "Synthetic Organic Chemicals,' 12th edition, RAYMOND BERTRAM EVANS. by Carbide and Carbon Chemicals Corporation, 1946, pages 20-21. REFERENCES CITED The following references are of record in the file of this patent: s