Патент USA US2404519код для вставки
v2,404,519 Patented July 23, 1946 I UNITED STATES PATENT OFF ICE 2,404.;519 METHOD OF MAKING AQUEOUS DISPER SION S CONTAINING POLYVINYL ACETATE AND WAX George Osman Morrison and Henry Michael Collins, Shawinigan Falls, Quebec, Canada, as signors to Shawinigan Chemicals Limited, Montreal, Quebec, Canada, a corporation of Canada No Drawing. Application May 15, 1943, Serial No. . 487,186. In Canada November 4, 1942 3 Claims. (Cl. 260-28) _ 2 1 Example I I This example demonstrates a preferred method INTRODUCTION This invention relates to emulsionsof polyvinyl acetate and to protective ?lms and coatings formed therefrom. of manufacturing a polyvinyl acetate emulsion . according to the invention. In one procedure the following constituents Polyvinyl acetate is particularly useful fur coat were employed at the approximate concentra-_ ing purposes in view of its excellent ?lm-forming tion. set out: properties, freedom from ‘brittleness, good colour and inertness to chemical in?uences. It is also tough and ?exible and has many other useful Water ' _____________ _‘____’_ ______ "grams" 800 do ' Vinyl acetate characteristics. Its speci?c properties may be readily varied to suit particular uses. I-Ipwever, 900 Emulsi?er-gum tragacanth ____ __per cent__ 1.25 Partially hydrolyzed polyvinyl acetate ' the use of aqueous emulsions of polyvinyl acetate having a polyvinyl acetate content of about 31% made from polyvinyl ace for forming moisture-proof coatings has been somewhat limited because of the sensitivity of 15 ; tate having a viscosity of “ at 7 centi these coatings, to re-pmulsi?cation andv cons: poises _________________ __per cent__ quent disintegration, 1.5 “Aerosol O. T.” (the sodium salt of the sul phonic acid of dioctyl succinic ester) ____ OBJECTS 1.1 per cent__ It is a principal object of the present invention 1 20 Paraffin wax, melting point 135‘ F____do___.. to provide new compositions of matter including 20 Catalyst-benzoyl peroxide _______ "grams" .69 polyvinyl acetate emulsions which are suitable for 1 By weight of the total charge. use in the preparation of waterproof sheets or An aqueous solution of the emulsi?er was ?lms, or useful for forming waterproof coatings charged into a kettle equipped with a re?ux con on various materials. It is a further object of the invention to provide a composition embody 25 denser and stirring blades. One type of equip ment, as used according to the following condi ing, in emulsion form, polyvinyl acetate as a ?lm tions, includes an aluminum pot about 8 inches forming constituent, and a moisture-proo?ng high by about 6 inches outside diameterlhaving agent with or without other modifying constitu aconcave bottom and no baffles. The stirrer ents such as for instance, softeners andlplasti shaft is of stainless steel. It embodies half an cizers. Further objects are to provide improved inch from the bottom 4 blades in a cluster 1 inch methods of making these compositions, improved by 1/2 inch bent at 45° for downward thrust; four methods of moisture-proof coating, improved inches from the bottom, a pair of blades (one at coatings and improved coated articles. each side of the shaft) each 21/2 inches by 1%, inch Tm: INVENTION 35 bent at an angle of 45° for downward thrust. The useful speeds, of the blades are‘about 500 to about These objects and others are accomplished ac 1800 revolutions per minute. cording to the invention by a composition which Stirring was started. The catalyst and water includes an aqueous emulsion of polyvinyl acetate as a principal ?lm-forming were added. Two minutes, stirring at about 1200. ‘ constituent, an oleag/inous or waxy protective agent, the composi 40 revolutions per minute was allowed and then they ‘ monomeric vinyl acetate was added slowly. The tion being capable of forming a ?lm having whole charge was then agitated for about 5— moisture-proof characteristics. This ?lm may be minutes in the cold to complete emulsi?cation laid down by ordinary methods of coating, but of the monomer. Stirring was continued at about preferred results are achieved by ?ashing the ?lm, (that is, by subjecting‘ it to a blast of hot air at a 45 the same speed and the temperature of the jacket raised to about 70° C. and maintained at this tem- ‘ temperature above the melting point of the waxy perature until the temperature of the charge agent. This causes the formation of .a bloom which protects the ?lm from re-emulsi?cation or reached about 66° C. from otherwise disintegrating. Then, as the reaction gathered momentum and re?ux commenced, the temperature of the jacket was gradually and suitably reduced in order to maintain a ‘moderate re?ux of about 1 percent, to about 11/2 percent of the total charge per hour. ' Articles made from materials which are not re sistant to water and coated in this manner may particularly be rendered completely advantageous moisture-proof. in the case of This conis tainers for aqueous materials. EXAMPLES To illustrate the invention in more detail, several examples will be given of speci?c embodi V ' ' Finally, the jacket temperature was reducedin ‘order to regulate the re?ux at the low rate. When the temperature of the charge had reached about ‘70° C. the temperature of the jacket was gradu allyraised from its minimum to about 82° C. ~ Thus, as the temperature of the charge increased, ments. These data are intended in an illustrative 60 the re?ux slowed up and the temperature of the - and not in a restricting sense. 2,404,519 4 charge followed closely behind that of the jacket. two ?ne cardboard containers C and D substan tially as in Example 2, at a temperature of about. When they were equal at about 82° C. re?ux . ceased and polymerization of the monomer was substantially complete. 20° C. _' ‘ A thin ?lm of wax was “slosh” coated over the ' The wax was then added and the emulsion stirred for about 10 minutes with the temperature ' maintained at about 82° C. The charge was then dried polyvinyl acetate ?lm of container C at about 90° C. Where there was no plasticizer present in the polyvinyl acetate, the resultant ?lm was brittle.v The composite ?lm was made cooled down to about 25° C. This was done over a period of about one hour with stirring con up of about 11/2 mil polyvinyl acetate and about‘ v tinued. The agitator was then stopped and the 10 1/2 mil wax. The container was ?lled with water which was batch of ?nished emulsion discharged. The re sulting composition had substantially the follow-‘ kept at about 30° C. After about two weeks the container and ?lm were intact, but creasing of ing characteristics: Viscosity of emulsion at 20° C__centipoises__ 300 - . v 1 15 the cardboard . resulted in extensive leakage. There was no re-emulsi?cation. ?iiiét?ltiai‘aaaa;;_11:'::_'_1';‘1‘iitii‘f:: 33 The ?lm 211 container D. wasallowed to dry Polyvinyl acetate viscosity___centipoises____ 30 at about 20 C. Re-eniulsi?cation. of the ?lm Stability . began after about 1 hour 5 contact with the water and the container collapsed after about 10 hours’ - Good 1011 total charge - l 20 contact with the water. - Emmple 2 ' ' te the respective char- ' act'Iélliqiztegsngfile‘ ‘1313:2211???’. . ind “?ashed” . ?lmsI . 1. ‘ ' ' Example 4 thAn emulsion was prepared as in Example 1 with e exception that the waxy agent was increased lald dOWn from a composltlon made according to Example " . to about 60% of the polyvinyl acetate - 25 A mm was as from this was.“ by sash" - . ‘ - asin?é‘stiieitiitln t‘?‘fé?litié?fgétitféé gslaétiggng’niggug igldcé onTghegenéilgga?ggziegg and the containers were subjected to the same ' tests as in Examples 1 and 2 to determine their made from ?ne 9ard1?°a?d of t’lte'type usually ability to withstand ‘water. The results were emptoyed for making hqmd c9ntamers' Th? ?lm 30 similar to those obtained with the ?ashed ?lms cgatmgothe surface of container A was dried at a out ° C. ' of Examples 1 and 2 with the exception that the - The ?lm was about 1 mil in thickness. It was pliable-and elastic. Water at about 30° C. was ,poured into this container. After about 72 hours 35 ' at room temperature the container Was practi- cally soaked through and had collapsed. The - ’ - ?lms of this example were more elastic. ' Emmple 5 The procedure of Example 1 was repeated with hydrogenated cotton seed oil replacing about 25% of the para?in wax, the oil'serving as a, push ?lm had almost completely re-emulsl?ed_ cizer for the wax. From the resulting emulsion The coating on container B was dried at about a ?lm was formed on the Surface of the con 20° C. It was then “?ashed" for abqut three 40 tamer. The ?lm was ?ashed and cooled and minutes in an air oven with a blast of all‘ heated tests for moisture-proof characteristics were car to about 110° C. The ?lm was about 1 mil in _ried out substantially as in Example 2. The ?lm thickness. It was Dhable and elastlc- A bloom had the same excellent moisture-proof character of wax had formed on the surface. Water at istics as container B (Ex. 1) and was at the same about 30° C. was poured into this container. 45 time more pliable and more capable of being After about two weeks at room temperature the creased without injury to the ?1m_ ' ?lm on the container was still intact. No re- emulsi?cati'on of the ?lm could be detected. Ea: m l Con- 6 15 “ 1’ es ‘ - tain'ers coated similarly to B were acceptable to In 011191‘ to demonstrate the manufacture and the trade for containing aqueous materials. 50 use Qf dl?erent ?lms formed according to the in Exambze 3 vention, the following Examples 6 to 15 are given. According to the natures and approxi The following example demonstrates the charmate concentrations of the ‘constituents set out - acteristics of a ?lm prepared from a polyvinyl ’ in the table, emulsions were made substantially acetate emulsion containing no wax but subse- 55 in accordance with Example 1. quently coated with wax. ' Containers were coated with these emulsions and tested for per An emulsion was prepared substantially as in Example 1 with the exception that no wax was incorporated. A ?lm was cast on the inside of formance substantially as in Example 2, and the performance of the coatings was as indicated in the table.v Table I Approximate Ex. Plasticizer _ Wax plasticizer Pliability wa?ggfgég of 128E336; bility of?lm Per cent Nil ____________________________ _. 30 Petroleum jelly, 15% __________ __ Petroleum jelly, 20%.. 70 _ 70 Petroleum oil, 12%...- 90 ---------------------- -- 100 ' ‘mgtssssntsts;gas-an;- i$ Petroleumjelly, 15% ____ ..'. ________ "do ....... __ 100 ‘ Nil ____________________________ _- Very pliable.-. 100 do _ . . . _ . _ _ _ . _ _ "do _______ __ 100 * The coating of Example '6 was not ?ashed, whereas those of Examples 7 to 15 were ?ashed. 2,404,519 6 , '5 "3 G. H." is trlethylene glycol di-hexoate, M. 17 is methyl phthalyl ethyl glycolate and B. 16 of the container from the plasticizer. ‘ Thus the concentration of the plasticizer may be increased is v,butyl phthalyl butyl glycolate. over what might otherwise be thought possible without danger of contaminating the contents. 1 Example 16 The emulsion was made as in Example 1 with the exception that the wax was added to the MANUFACTURING PROCEDURE While substantially conventional methods are charge'before the start of the reaction. employed in making ‘the emulsion, in order to The emulsion was used for coating containers improve still further the qualities of the emulsion in procedures similar to those of Example 2. The 10 as a coating material, special steps are taken in results as regards the characteristics of the ?lms the process of manufacture. Up to the com and their moisture-proof performance were sub pletion of polymerization the procedure is con stantially the same as those of Example 2. ventional for the manufacture of polyvinyl ace tate emulsions, with the exception that the waxy DETAILED DESCRIPTION 15 agent is added as an additional phase either While the examples demonstrate various prior to, during, or after polymerization. The speci?c types of coating-emulsions according tov procedure then departs from the conventional in that the wax-containing emulsion is cooled the invention, it will be obvious to one skilled in the art that the particular constituents, com very slowly, i. e. over a period of about 40 min positions, conditions and concentrations set out 20 utes to about 2 hours or more, from the upper temperature resulting from polymerization of may be varied widely within the scope of the about 84° C. to room temperature of‘ about 20° C. invention. By following this procedure, emulsions‘ can be Pao'rnc'rrvr: AGENT made having viscosities of between about 200 For instance, the nature of the protective .25 and about 2000 centipoises. Those in the neigh agent may be varied. Suitable agents are ole borhood of 300 centipoises are preferred. These emulsions ?ow readily, thus having excellent aginous or waxy materials such as for instance; hydrogenated natural oils and fats, for example, characteristics for coating. In contrast, similar cotton seed oil, linseed oil; saturated natural oils, emulsions which were cooled rapidly, exhibited for instance, animal oils, sperm oils; paraf?n 30 viscosities of as high as 7,000 centipoises. The type oils and waxes, for example, micro-crystal latter emulsions were not stable, and ?lms laid line paraf?n wax and para?in oil; or mixtures down from them were poorly flexible.‘ From this, of these substances. These agents or mixtures it would appear that slow cooling causes the for mation of small discrete wax particles as a third thereof should have a melting point of between about 47° F. and about 140° F. and the neces 35 phase of the emulsion. In most cases, these wax sary flexibility when solid and other coating particles were of a size between about 4p and characteristics as will be understood by those about 2011.. skilled in the art. The melting point will vary In general, the normal constituents of the emulsions, e. g. emulsifying agents, catalysts, depending upon the particular use to which the coating is put. It is preferable that the melting 40 modifying agents, etc. may be those generally employable in the manufacture of aqueous emul point be between about 100° F. and about 140° F. sions of polyvinyl acetate. Preferred types of Preferred agents are paraf?n waxes. The useful range of concentration of the pro emulsions may, however, be manufactured by following the teachings of the present application tective agent is between about 12% and about in conjunction with those of the following co 40% calculated by weight on the total charge. The preferred range of concentration is between _ about 12% and about 20% . Monrmrmc AGEn'rs The coating emulsion is preferably modi?ed to make the resulting ?lm/ more ?exible and to render it more ?owable than it would be with wax alone as a protective agent. This may be effected by adding a softener for the wax and/or a plasticizer for the resin. An effective softener is hydrogenated cotton seed oil, conveniently the commercial product known as “Crisco,” employed at concentrations of between about 3% and about 15% of/lthe total charge. Other oleaginous soft pending applications, _H. M. Collins, S. N. 457,337, Sept. 4, 1942, relating to the use of emulsifying agents of particular types, and M. Kiar, S. N. ,5 457,339,‘Sept. 4, 1942, relating to the use of par ticular conditions to in?uence the characteristics of the resulting polyme . y' COATING ' ' Y , The formation of the ?lm or coating on’ the 55 surface of the article being coated may be ef fected in a conventional manner. In order, how ever, to achieve the preferred results of which‘ the present invention is capable using a relatively thin coating, the dried coating is ?ashed at a _ teners such as for instance petroleum jelly, may 60 temperature above the melting point of the waxy be employed at similar concentrations. , protective agent. This apparently has the eifect To‘improve the’ properties of the ?lms still of bringing the wax to the surface to form a further, a plasticizer for the resin may be em “bloom” which acts to prevent penetration by ployedin conjunction with the softener. This moisture. plasticizer must be non-toxic and capable of act 65 The thickness of the ?lms formed may vary ing to plasticize the resin at a concentration in considerably. Satisfactory moisture-proof ?lms for commercial purposes are in the neighborhood su?icient to contaminate the coating with odour or taste-giving properties. Suitable plasticizers ' of 1 mil in thickness. of this type are butyl phthalyl butyl glycolate The?lms may also be modi?ed by treatment and methyl phthalyl ethyl glycolate. The plas 70 with the pigments or fillers usually employed with’ polyvinyl acetate resins. Food products and ticizers are preferably used at concentrations of between about 3% and about 5% by weightofj the total charge. When the coating is/?a'shed according ,to the present invention‘: the wax bloom has the effect of isolating the contents / other articles can be coated directly with ?lms as opposed to coating a-container. Self-sustaining ,?lills can also be formed and rendered water ’ proof by the present teachings. anemia V _7 V ‘O’ Y, limitations shall be placed, th'ereon as may, be 7 required by the state of the prior art.v These coatings have a widevariety or uses. , l A principal utility lies in rendering water-perme I ; 7, ‘ able materials waterproof. This is of particular advantage'for the manufacture of cardboard con tainers for aqueous materials; particularly foods and beverages, such as milk, honey, fruit juices, We claim: uses will also be apparent to those skilled in i the art. - V a , y ' l. A process of preparing a coating composi a 1 etc. Other materials may also be coated such as \leather, fabrics, cellulosic materials such as for ‘instance. paper of various types. Many other ' m tion comprising adding a wax to an aqueous dis persion of polyvinyl acetate produced by emul sion polymerization. in the presence of an emulsi fying agent effective to stabilize said dispersion, said polyvinyl acetate beingpresent in an amount ranging from about 30 to about 70% of the said dispersion, said 'wax being present in an amount rangingfroxn about 12 to about 40% of the total ' composition,’ the wax being added when the dis persion has a temperature above the melting 3coating” is intended to indicate a coating able point of the wax, then cooling the dispersion jto withstand ‘water effectively for the purposes 15 slowly with stirring to about room temperature to which the coated material is to be put. For during a period of about 40 minutes to 2 hours instance, containers for aqueous liquids must'be whereby the ,wax constitutes a ph'ase of said dis su?iciently water-proof that‘ the container‘ will, persion in small discrete particles. ‘ ‘under the conditions of manufacture, handling 2. A process accordingto claim 1 wherein the V In this speci?cation, the term "waterproof and use, stand up to the satisfaction of the trade 2o wax is a para?in wax having a melting point 1 and of consumers. within a range from about 47° F. to about 14=0f7 F. It will be understood that, without departing ' 3. A process according to, claim 1 wherein ‘from 'the-spirit'of the invention or the scope of there 'is added to the dispersion an oleaginous softener for the wax and a plasticizer for-the fthe claims, various modi?cations may be made ‘inqthe speci?c expedients described. Thelatter ‘are illustrative only and not offered in a re stricting sense, it being desired that only 'such 25 polyvinyl acetate. > ' GEORGE OSMAN MORRISON. HENRY MICHAEL COLLINS.