19)
`United States Patent
`4,316,852
`Feb. 23, 1982
`Blachford
`[45]
`
`[11]
`
`[54] MANUFACTURE OF METALLIC SOAPS
`[75]
`Inventor:
`John Blachford, Westmount, Canada
`[73] Assignee:, H,L. Blachford, Limited, Montreal,
`Canada
`
`[21] Appl. No.: 130,080
`[22] Filed:
`Mar. 13, 1980
`[30]
`Foreign Application Priority Data
`Mar. 29, 1979 [CA] Canada .......eccsecsersseeresenetees 324476
`[52] Unt, C13 occeeseetceeesees C11C 1/00; COIF 7/24
`
`devvsavene 260/414; 260/429 R;
`[52] U.S. Cl. ....
`260/429.9; 260/435 R; 260/439 R
`[58] Field of Search ........:s0 260/414, 429 R, 435 R,
`260/429.9, 439 R
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`_ 260/414
`293,344 2/1884 Michaudetal. ..
`
`8/1940 Licata .....secsseseceeseseeereeees 260/414
`2,211,139
`8/1980 Logan et al. .t...eeeeees 260/415
`4,218,386
`
`Attorney, Agent, or Firm-—Bachman and LaPointe
`
`ABSTRACT
`[57]
`Metallic soaps, particularly zinc soaps are produced
`from a reaction mixture initially comprising a metal
`oxide or hydroxide, for example, zinc oxide, water and
`a glyceryl ester, particularly a triglyceride, the ester and
`said metal oxide or hydroxide being present in at least
`approximately stoichiometric amounts;
`the reaction
`mixture is agitated and the reactants are reacted in the
`agitated mixture to produce a metallic soap and glycer-.
`ine, at a temperature at which the metallic, soap is mol-
`ten, in the presence of an excess of water effective to
`dissolve the glycerine formed in the reaction mixture
`such that reaction between by-product glycerine and
`the product metallic soap is substantially hindered,
`eventually the reaction mixture is allowed to separate
`into an aqueous layer and a molten layer of product
`metallic soap under a pressure such that the aqueous
`layer is essentially quiescent, and the molten metallic
`soap layeris dissociated from the aqueous layer; in this
`way metallic soaps of high purity can be obtained.
`
`Primary Examiner—John F. Niebling
`
`19 Claims, No Drawings
`
`000001
`
`Exhibit 1109
`Exhibit 1109
`ARGENTUM
`ARGENTUM
`IPR2017-01053
`IPR2017-01053
`
`000001
`
`

`

`
`
`1
`
`4,316,852
`
`2
`Zinc stearate is manufactured commercially employ-
`ing this process by the action of sodium stearate on a
`solution of zinc sulphate.
`
`(ii) REACTION OF METALS, METAL OXIDES
`OR METAL HYDROXIDES WITH MOLTEN
`FATTY ACIDS
`
`(a) Fusion Process
`Only certain metallic soaps can be formed by this
`method. The metallic soap is formed by reacting the
`molten fatty acid with the appropriate metal: oxide or
`hydroxide at a temperature above the melting point of
`the metallic soap to be formed, and generally at a tem-
`perature considerably above this, because, during the
`reaction, water is formed and this must be drivenoff.
`Generally, the reaction requires in the neighbourhood
`of 5 hours for completion. This process can only be used
`for making metallic soaps which are pourable in their
`molten state. It, therefore, cannot be used for such me-
`tallic soaps as calcium or barium stearate, butit is suit-
`able for zinc and lead stearates. The final productis in
`the form of flakes or lumps and a considerable energy
`must be expendedin grinding it to the required very fine
`particle size. This process does have the advantage of
`not requiring the use of caustic soda, and no filtering or
`drying is required. It also does not lead to any water
`pollution or the consumption of any water.
`
`(b) Modified Fusion Process
`This is much like the fusion process (a), except that a
`small amount of water is added to the mixture of molten
`fatty acid and metal oxide or hydroxide. The wateracts
`as a catalyst and allowsthe reaction to be carried out at
`a somewhat lower temperature, and more quickly. The
`final product produced is very muchlike, if not identi-
`cal to, that resulting from the fusion process (a).
`
`(c) Fusion in an Aqueous Slurry
`In this process, the moltenfatty acid is first emulsified
`in water using an appropriate emulsifying agent. To this
`aqueous emulsion, is added an aqueousslurry of the
`metal oxide or hydroxide. The metallic oxide or hy-
`droxide reacts with the fatty acid to form the metallic
`soap. This is then removedbyfiltration, during whichit
`is washed, and then it is dried and ground. The product
`is considerably easier to grind becauseit is produced in
`the form of coarse particles. These particles, however,
`are much coarser than those produced in the double
`decomposition process.
`.
`
`(d) Miscellaneous Fusion Methods
`Occasionally, it is possible and of commercial value
`to react certain metals directly with molten fatty acid.
`For example, iron stearate may be prepared bythis
`method; however, hydrogen rather than water is actu-
`ally a by-product of reaction and, because the reaction
`generally has to be carried out at.an unusually high
`temperature, the colourof the resulting metallic soap is
`poor.
`
`SUMMARY OF THE INVENTION
`
`The present invention provides a new and improved
`method for the manufacture of metallic soaps that are
`pourable in their molten state, utilizing oxides or hy-
`droxides of divalent metals and. appropriate fats or oils
`rather than the fatty acids derived from such fats and
`oils.
`
`MANUFACTURE OF METALLIC SOAPS
`
`BACKGROUNDOF THE INVENTION
`
`1. Field of the Invention
`This invention relates to the manufacture of water-
`insoluble heavy metal soaps or metallic soaps and, more
`particularly, it relates to the manufacture of those me-
`tallic soaps which, in their molten state, are pourable
`liquids. It is therefore chiefly concerned with the soaps
`of cadmium, cobalt, lead, manganese, copper and zinc.
`2. Description of the Prior Art
`Metallic soaps have found wide application in indus-
`try, for example, as waterproofing agents, thickening
`and suspending agents, and as lubricants; they are also
`employed in cosmetics, lacquers, plastics,
`in powder
`metallurgy, as mold release agents, flattening agents,
`fillers, anti-foaming agents and driers in paints, and in
`tablet manufacture. They are also used as heat andlight
`stabilizers for plastics, especially polyvinyl chloride.
`The most common metallic soaps are those prepared
`from calcium, zinc, magnesium, barium and aluminum.
`The heavy metal or metallic soaps have convention-
`ally been prepared from the metal oxides or metal salts
`and aliphatic carboxylic acids, particularly the higher
`fatty acids containing from about 12 to 22 carbon atoms,
`which acids are knownandsold to the industry as com-
`mercial fatty acids. The commercial fatty acids as com-
`monly used are usually mixtures of higher fatty acids in
`which the nameattached to them maybe only the domi-
`nant acid of the mixture. In some grades of commercial
`stearic acid, however, the dominant fatty acid is not
`stearic acid but anotherfatty acid, for example, palmitic
`acid.
`The three basic methods conventionally employed
`for the manufacture of metallic soaps are described in
`U.S. Pat. No. 2,890,232, Russell H. Rogers, Jr. et al,
`issued June 9, 1959 and U.S. Pat. No. 3,803,188, Leon-
`ard Frank Scott et al, issued Apr. 9, 1974. The manufac-
`ture of metallic soapsis also described in U.S. Pat. Nos.
`2,945,051, Gerald M. Davis, issued July 12, 1960 and
`2,650,932, Leonard M. Kebrich et al, issued Sept. 1,
`1953.
`Metallic soaps of the higher fatty acids, the most
`common of which are the metallic stearates derived
`from commercial gradesofstearic acid, are prepared by
`two principal methods:
`
`G) DOUBLE DECOMPOSITION PROCESS
`
`This is the oldest process and probablystill the one
`most commonly used. A hot aqueous solution of the
`sodium salt of the fatty acid is first prepared by the
`addition of aqueous caustic soda to a mixture of the
`fatty acid in hot water. The sodium salt is then reacted
`with a hot aqueoussolution of an appropriate metal salt.
`Theinsoluble precipitate of the fatty acid metallic soap
`is filtered, washed free of the soluble sodium salt, dried,
`and groundto a fine powder. By propercontrol of the
`reaction conditions, including temperature, rate of addi-
`tion of reactants, and degree of dilution, a product with
`a fine particle size and of high purity can be obtained.
`The production cost, however, is high, especially be-
`cause of the filtration, washing, and drying operations
`required. The process also has the drawbackthat fre-
`quently it creates a water pollution problem.
`
`15
`
`20
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`000002
`
`000002
`
`

`

`-4,316,852
`
`4
`reacted with the glyceryl ester of formula (I), which
`may be a mono-, di- or triglyceride, and water, with
`elimination of glycerine. The reaction proceeds in ac-
`cordance with equation (I)—
`
`pH2C(OR ;)CH(OR2)CH2(OR3)+ qMO(or
`M(OH)2)+ qH2O—-pCH20H.CH(OH).C-
`H2OH+qR4gOMORs
`
`H2C(OR } )CH(OR2)CH2(OR3)
`
`“(12
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`The method ofthe invention employs a reaction be-
`tween a metal oxide or hydroxide, a glyceryl ester,
`particularly a mono-, di or triglyceride, preferably a
`triglyceride, for example, unhydrogenated or hydroge-
`nated, naturally occurring, vegetable oil or animal fat,
`and, in the case of the oxide, water. A particular advan-
`tage of the method of the invention, which employs a
`‘glyceryl ester, particularly a triglyceride, instead of a
`fatty acid or mixture of fatty acids derived from the’
`corresponding triglyceride, is that it is urinecessary to
`carry out the procedure offirst deriving the acid or
`acids from the corresponding glyceryl ester prior to
`forming the metallic soap by reacting the metal oxide or
`hydroxide with the fatty acid;
`instead,
`the metallic
`soaps are formed directly from the glyceryl esters. Fur-
`thermore, unlike the double decomposition process, no
`caustic soda is required, and it is not necessary to carry
`out any filtering, washingor drying.
`In one embodimentof the process of the invention an
`oxide of a heavy metal, particularly a divalent metal, is
`
`3
`The method of the invention permits the production
`of metallic soaps in good yield and purity with low free
`fatty acid content.
`According to the invention there is provided a pro-
`cess for producing a metallic soap having a viscosity
`suchthatit is a pourable liquid when molten, of a mono-
`carboxylic acid of the formula R-COOHwherein R is a
`linear or branched, saturated or unsaturated, unsubsti-
`tuted or substituted by one or more hydroxy groups,
`10 wherein Rj, R2 and R3 are as defined above in formula
`aliphatic hydrocarbon radical of 5 to 21 carbon atoms,
`which comprises: (i) forming a reaction mixtureinitially
`(D, M is the metal, R4 and Rs, which may be the same
`comprising a metal component comprising a metal
`or different, are acyl radicals selected from Rj, R2 and
`oxide selected from the group consisting of oxides of
`R3,p is an integer of 1 or 2.andqis an integerof 1 or3.
`cadmium, lead and zinc or a metal hydroxide selected
`Whenthe glyceryl ester is a monoglyceride, p is 2 and
`from the group consisting of hydroxides of cobalt, man-
`q is 1; when the glyceryl ester is a diglyceride, p and q
`ganese, and zinc, water and a glyceryl ester of formula
`are both 1; and whenthe glycerylesteris a triglyceride,
`(D:
`p is 2 and q is 3.
`In another embodiment a heavy metal hydroxide is
`employedin place ofthe oxide and no water is required
`in the chemical reaction with the glyceryl ester al-
`though wateris still required in the reaction mixture to
`dissolve the glycerine; the values for p and q are as
`indicated in equation (I) except that for the water as
`reactant q is o.
`The heavy metal of the metal oxide may be cadmium,
`lead or zinc; the heavy metal of the metal hydroxide
`may be cobalt, manganese, copper or zinc. The pre-
`ferred metal oxide is zinc oxide; the preferred metal
`hydroxide is cobaltous hydroxide. Although oxides and
`hydroxides of some of the alkaline earth and other
`heavy metals will react with glyceryl esters, the result-
`ing metallic soaps do not form pourable liquids when
`heated above their melting points and, consequently,
`.the separation of the resulting metallic soaps from the
`solution of by-product glycerine and wateris difficult
`and not commercially practical. The present invention
`is concerned only with those metallic soaps which are
`pourable liquids at temperatures exceeding their melt-
`ing points. For the purposes of this invention, a pour-
`able liquid is defined as one having a viscosity of less
`than 1,000,000 and preferably less than 500,000 cps.
`In a preferred embodiment of the process of this
`invention, the glyceryl ester is a triglyceride selected
`from the triglycerides which are derived from, or con-
`tained in, animal or vegetablefats oroils, since these are
`more readily available commercially. Such triglycer-
`ides include those in which the aliphatic hydrocarbon
`radical is saturated or unsaturated.
`Triglycerides in which one or more of Rj, R2 and R3
`has less than 6 carbon atoms or more than 22 carbon
`atoms will produce metallic soaps by the process of the
`invention, however, such triglycerides are rare and not
`generally commercially available.
`A large number oftriglycerides, which are derived
`from or contained in animal or vegetable fats or oils,
`may be used in the invention. The degree of unsatura-
`tion of a triglyceride is indicated by the iodine value.
`The higher the iodine value, the higher the degree of
`unsaturation. Frequently, it is desirable to reduce the
`degree of unsaturation of a triglyceride and this can be
`accomplished by reacting the triglyceride with hydro-
`gen, the process being calléd hydrogenation. The de-
`gree to which the unsaturation is reduced is determined
`by the amount of hydrogen whichis allowed to react
`with the triglyceride.
`Occasionally, complete saturation or hydrogenation
`is desired and, in this case, the iodine value is reduced to
`
`wherein R}, R2 and R3, which may be-the same ordif-
`ferent are selected from the group consisting of hydro-
`gen and linear or branched, unsubstituted or substituted
`by one or more hydroxyl groups, saturated or unsatu-
`rated aliphatic hydrocarbon acyl radicals of 6 to 22
`carbon atoms, provided that at least one of Ry, R2 and
`R3 is an acyl radical, said ester and said metal oxide or
`hydroxide being present in at least approximately stoi-
`chiometric amounts;(ii) agitating said reaction mixture;
`(iii) reacting the reactants in the agitated mixture to
`producea metallic soap.ofthe carboxylic acid and glyc-
`erine, at.a temperature at which the metallic soap is
`molten, in the presence of an excess of watereffective to
`dissolve the glycerine formed in the reaction mixture
`such that reaction between the reactants proceeds in
`favour of metallic soap production and the reaction
`between glycerine and the product metallic soap is
`substantially hindered; (iv) continuing the reacting in
`(ii) until substantially no more metallic soap is formed;
`(v) allowing the reaction mixture to separate into an
`aqueous layer and a molten layer of product metallic
`soap substantially free of metallic oxide or metallic
`hydroxide, carboxylic acid and glyceryl] ester, under a
`pressure such that said aqueous layeris essentially quies-
`cent, and(vi) dissociating the molten metallic soap layer
`from the aqueouslayer..
`.
`
`5
`
`20
`
`we. 5
`
`45
`
`60
`
`000003
`
`000003
`
`

`

`4,316,852
`
`6
`colour of the metallic soap produced is whiter and the
`colourstability on heating is greater.
`- The melting pointof the metallic soap depends on the
`degree: of. unsaturation in:
`the «aliphatic: hydrocarbon
`-radicals, or in other. words:it depends on the iodine
`
`5
`
`5
`essentially zero..In other instances, it may be sufficient
`to merely reduce the iodine valuefrom, say, 40 to 15.
`Thetriglycerides which occur naturally differ widely
`in iodine value and also in composition. This iis demon-
`strated in Table I below.
`TABLE I
`APPROXIMATE COMPOSITION OF VARIOUS UNHYDROGENATEDFATS AND OILS.
`APPROX. NATURE AND
`APPROX. NATURE AND AMOUNTS(IN
`AMOUNTS(IN
`WT.%) OF DERIVABLE
`UNSATURATED.
`FATTY ACIDS
`:
`.
`Unhydro- ©
`
`
`genated lino-_lino-Iodine . . : ricino-,
`
`
`
`
`Fat or Oil|
`_
`leic
`Value
`caprylic © capric
`lauric.__myristic palmitic
`stearic
`oleic
`erucic
`leic
`lenic
`Castor
`85
`_
`_
`_—
`_
`_—
`0.3
`8.2
`_
`87.6
`3.6 7°
`Coconut
`10
`8.0
`7.0 48.2
`17.3
`8.8
`2.0
`60
`~
`_
`2.5
`—
`Cotton-
`:
`seed
`110
`—
`>
`=-
`0.5
`22.9
`+ 2.2
`24.7
`_
`=
`4970-7
`Lard
`55.
`_
`+
`_-
`1.0
`26.0
`110
`48.7
`—
`—
`12.2
`+,0.7
`Linseed
`180
`_
`—
`—_
`_
`6.4
`45°
`21.0
`_
`_
`174
`50.6
`Paim
`50
`—
`_
`_
`1.0
`42.5
`4.0,
`43.0
`_
`_ 950°
`Peanut
`90
`_
`—
`_
`_—
`7.0
`5.0
`60.0
`_
`_—
`210° °° —
`Rape-
`Hh
`seed .
`100
`~
`_—
`_—
`1.0
`10
`1.0
`29.0
`50.0
`_-
`15.0
`1.0
`Soya-
`bean
`Beef
`Tallow.
`
`WT. %) OF DERIVABLE SATURATED
`
`FATTY ACIDS
`
`“
`
`_
`
`—
`
`_
`
`_—
`
`_
`
`2.20
`
`6.5
`
`35.0
`
`.
`
`4.2
`
`15.7
`
`28.0
`
`,
`
`=
`
`444 0° —
`
`—
`
`_—
`
`52.6
`
`2.2
`
`.
`
`8.0
`
`0.4
`
`:
`
`_
`
`—_
`
`:
`
`:
`
`135
`
`40°:
`
`During hydrogenation,the double bondsin the unsat-
`urated aliphatic hydrocarbon radicals ofthetriglycer-
`ide molecules are gradually replaced with single bonds
`and, in this way, the chemical composition is signifi-
`cantly changed. For example, when the unsaturated
`hydrocarbon radical of oleic acid radical is hydroge-
`nated, the oleic. acid is convertedto stearic acid. The
`typical composition of the naturally occurring triglyc-
`erides of Table I after hydrogenation is shown in Table
`II below.
`
`30
`
`value of the triglyceride employed. The lower the io-
`dine value,i.e., the higher the saturation ofthe aliphatic
`hydrocarbon radicals, the higher the. melting point of
`the metallic salt. For a given chain length or numberof
`carbon atomsin a fatty acid aliphatic hydrocarbon radi-
`.cal, the greater the number of carbon-carbon double
`. bondsin the chain, the lower will be the melting point;
`for example zinc stearate melts at 120° C. and zinc ole-
`ate melts at 70° C.
`In carrying out the process of the invention on a
`
`TABLEII
`APPROXIMATE COMPOSITION OF VARIOUS HYDROGENATEDFATS ANDOILS
`APPROX.NATURE
`AND AMOUNTS
`(IN WT. %) OF
`DERIVABLE UN-
`SATURATED
`FATTY ACIDS
`
`APPROX. NATURE AND AMOUNTS(IN WT..%)
`OF DERIVABLE SATURATED
`FATTY ACIDS
`
`Hydro-
`genated
`Fat or Oil
`Castor
`Coconut
`Cotton-
`seed
`Lard
`Linseed
`Palm
`Peanut
`Rape-
`seed ©
`Soya-
`bean
`Beef
`Tallow
`
`Todine
`Value
`2
`1
`
`.
`
`5
`3
`2
`1
`4
`
`6
`7
`
`2
`
`caprylic
`—
`4
`
`capric
`—
`6
`
`lauric myristic
`_—
`—
`»49 °
`21
`
`palmitic
`2
`10
`
`>
`
`stearic
`10
`10
`
`.
`12-hydroxy-
`stearic
`88
`_
`
`other
`
`oleic ,
`_
`_-
`
`-
`_
`_—
`=
`—
`
`_
`‘
`_
`
`—
`
`-
`—
`—
`_
`_
`
`—
`_
`
`_—
`
`.
`
`-
`—
`_—
`—_
`—
`
`_
`co
`
`_
`
`.
`
`.
`
`1
`1
`—_
`1
`_
`.
`
`1
`oo
`.
`3
`
`23
`26
`6
`43
`7
`
`1
`7
`
`28
`
`70
`69
`92
`55
`81
`
`39
`85
`
`65
`
`-
`—
`—
`_
`—
`
`_
`—
`
`_—
`
`£
`
`a
`
`6
`4
`2
`|
`5
`
`7
`8
`
`2
`
`51 Behenic
`.
`
`.
`
`.
`
`.
`
`:
`
`It is especially preferred to employ a triglyceride
`having an iodine value of less than 50, and preferably
`less than 10. Some of the naturally-occurring triglycer-
`ides have an iodine value ofthis order, but others must
`be hydrogenated to convert
`them into triglycerides
`having a low iodine value. Theadvantagein employing
`triglycerides. having. a lower iodine value ‘is: that the
`
`65
`
`commercial scale, commercially available materials are
`utilized.It will be appreciatedthat commercially avail-
`able materials are of varying grades of composition.
`In the specification, identification of materials by the
`chemical nameis intended to embrace boththe chemi-
`cally pure material and the commercially available
`product. For example, the “zinc stearate” produced in
`
`000004
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`

`4,316,852
`
`7.
`the examplesillustrating this invention::will be’a:com-
`mercial grade of zinc stearate, similar to the product
`derived commercially by reacting zinc oxide with “stea-
`tic acid”, which term covers such: products’ as-single-
`pressed, double-pressed and triple-pressed stearic acid
`and also mixtures of fatty acids derived from the com-
`plete or incomplete hydrogenation and:subsequenthy- "'
`drolysis of certain animal and vegetablefats and oils, for
`example, tallow fat and soybeanoil..
`:
`The triglycerides employed..in the invention have
`mixtures of aliphatic hydrocarbon radicals similar to
`those in the fatty acids derived from them, so that the
`composition of the metallic soaps producedin this in-
`vention from a particular fat or oil will be similar to that
`produced by the conventional method from a-mixture
`of fatty acids derived fromthat fat oroil.
`Thusit will be recognized that the nature of the com-
`mercially available reactants employed in the invention
`results in metallic soap products which, essentially, are
`mixtures of different metallic soaps rather than a single
`metallic soap. Of course, the process of the invention
`can be utilized to produce particular metallic soaps
`which are not mixtures by appropriate‘selection of tri-
`glycerides in which all the aliphatic hydrocarbon radi-
`cals are the same, but for most purposes such selection
`is unnecessary as the different metallic soaps in.a metal-
`lic soap product havesufficiently similar properties and
`characteristics for most industrial uses.
`_
`AS illustrative of thenovel process of the invention,
`zinc stearate can be‘prepared byheating together under
`conditions of agitation in an enclosed reactor (for exam-
`ple, ann autoclave), zinc> okide, hydrogenatedtallow, and
`
`20
`
`25
`
`8
`ofthie’ aqueous glycerine at the temperature in the auto-
`clave: Under these conditions of temperature and pres-
`sure and in the absence of agitation, the molten zinc
`soap forms a‘discréte layer above an aqueous layer of
`glycerine. Having obtained this layer separation, it isa
`simple matter to drain off the lower aqueous layer be-
`fore draining off the molten zinc soap into a separate
`container.
`;
`‘It is ‘an important aspect of this invention that the
`reaction conditions be such that a thorough separation
`of the metallic soap from the aqueous glycerine is
`achieved. Table HII below shows the dependence of
`specific gravity on temperature for several metallic
`. soaps and on both temperature and glycerine content
`for ‘several different solutions of glycerine in water.
`These results show that when certain metallic soaps are
`in the presence of certain glycerine in water solutions at
`a particular temperature,
`the specific gravity of the
`molten metallic soap and that of the aqueous glycerine
`solution are equal and it
`is therefore impossible to
`achieve the formation of the two distinct layers of im-
`miscible materials. If the specific gravity of the molten
`metallic soap is only slightly less or slightly greater than
`that of the aqueous solution, it is very difficult, and
`frequently impossible, to obtain a complete separation.
`It is therefore appropriate to control the process con-
`‘ditions such that there is an adequate difference in the
`specific gravities of the molten metallic soap andthe
`aqueous glycerine to permit complete separation. to
`form distinct layers. Thespecific gravities may suitably
`be alteréd by varying the temperature or by diluting the
`reaction mixture with further quantities of water.
`TABLEIII
`‘SPECIFIC GRAVITY FOR VARIOUS METALLIC SOAPS AND FOR
`pot
`VARIOUS AQUEOUS GLYCERINE SOLUTIONS
`TEMPERATUREIN °C.
`.
`20 50 185100=130150 200
`
`
`
`
`_ MATERIAL.
`0.908
`1.025
`1.012
`0.983
`0.960
`0.943
`0.891
`10% glycerine in water.
`L051
`1.038
`1.008
`0.986.
`0.969
`0,934
`. 0.918
`20% glycerine in water
`1077
`1.063
`1.033
`. LON
`0.994.
`0.961
`0.945
`30% glycerine in water
`1.104
`1.089
`1.058
`1.036
`1.019
`0987
`0972
`40% glycerine in water
`cadmium stearate
`1.21
`100
`0.99
`0.95
`1.10
`copperstearate
`cobalt stearate
`13
`lead stearate
`1.37
`122 |
`manganese stearate °°
`zinc. stearate
`1.09
`1.12
`zine palmitate
`
`.
`
`M170 1S
`
`092
`
`0.91
`
`0.89
`
`water according to the following equation ‘QD:
`
`:
`i
`2CH2(OR1)CH(OR2)CH2(OR3) + 3ZnO + 3H20 ——> m
`(hydrogenated tallow)
`2CH2OHCHOHCH20H + R4gOZnORS
`(glycepine)
`(zinc soap)
`
`where Ry, R2 and R3 are acyl radicals as defined previ-
`ously and are the sameor different for each molecule of
`hydrogenated tallow, and are present in amounts corre-
`sponding approximately to.the composition. given in
`Table I, and R4 and Rs, which may be the same or
`different, are acyl radicals selected from Ri, Ry and-R3.
`‘When the reaction is complete,
`the agitation is
`stopped and the temperature is maintained. above the
`melting point of the product.zinc soap. In a preferred
`embodiment the pressure is increased by the introduc-
`tion. of an inert gas, for example, air or nitrogen, so that
`the pressure is substantially above the vapour pressure
`
`50
`
`35
`
`60
`
`65
`
`An important feature of the invention is that during
`the process step leading to the separation of the two
`layers, one layer composed of molten metallic soap and
`the other of an aqueoussolution of glycerine, the pres-
`sure in the reactor should exceed the vapour pressure of
`the aqueous solution of glycerine at the temperature
`within the reactor; otherwise the aqueoussolution will
`continue to boil and this boiling action will effect an
`agitation that will make it impossible to achieve a com-
`plete separation of the metallic soap from the glycerine
`in water solution. At this stage of the process the pres-
`sure is controlled so that the solution forms an essen-
`tially quiescent layer.
`:
`Ifthe reactorjs air-tight and theairinitially present in
`the reactor is not expelled then the pressure will remain
`above the vapour pressure of the aqueous glycerine
`solution: at all times during the course of the reaction
`and, therefore, it will be possible to obtain a phasesepa-
`ration.once the reaction has been completed and the
`
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`9
`agitation stopped since a quiescent aqueouslayer will
`then form. However, as soon as the removal of one of
`the phases fromthe reactor is begun, for example, .by
`draining or decanting, the pressure in the reactor will
`decrease, and, when it equals the vapour pressure ofthe
`aqueous solution in the reactor, boiling will commence,
`resulting in the mixing of the two phases orlayers. In
`order to achieve the removal of one or the other layer
`from the reactor without disrupting the quiescentstate,
`an inert gasis suitably introduced so that the pressure in
`the reactor is such that it always exceeds the vapour
`pressure of the aqueous solution as long:as the two
`phases are presentin the reactor following the reaction.
`Ofcourse, other meansof ensuring an adequate pressure
`in the reactor can also be employed, such as maintaining
`a very high pressure in the reactor throughoutthe pro-
`cess so that during removalof oneofthe layers from the
`reactor, the pressure doesnot fall.as low. as the vapour
`pressure of the aqueoussolution.
`If the metallic soap melts considerably below 100° C.
`and is a pourable liquid below this temperature, the
`reaction can be carried out at a temperature below 100°
`C., and the separation of the molten metallic soap from
`the glycerine in water solution can be obtained at atmo-
`spheric pressure. However, very few metallic soaps of
`commercial value have melting points below 100° C.
`and, furthermore, the rate of reaction at temperatures
`below about 100° C.is impractically slow.
`The molten metallic soap may form the upper or
`lower layer in the reactor depending on the relative
`specific gravities of the metallic soap and the aqueous
`glycerine layer at the temperature in the reactor, shown
`in Table III above.
`~
`Therelative amounts of the three components in the
`reaction mixture is important. An excess of the metal
`oxide or hydroxide above the stoichiometric amount
`required to completely react with the triglyceride will
`lead to contamination of the metallic soap with the
`metal oxide or hydroxide. If the amount of metal oxide
`or hydroxide is below that required stoichiometrically,
`the product metallic soap will be. contaminated with
`unreacted triglyceride and possibly somefree fatty acid.
`The amount of water required is particularly impor-
`tant; but, in this instance, the amount by weight must be
`considerably greater than the amount by weight of
`glycerine produced. This is because the reaction be-
`tween the glyceride, metal oxide and water or glyceride
`and metal hydroxide is a reversible reaction and, if only
`the stoichiometric amount of water is used, the reaction
`does not proceed nearly to completion. In order to
`promote the metallic soap-producing reaction over the
`reverse reaction it is necessary to employa large excess
`of water to dissolve the by-product glycerine. If insuffi-
`cient water is available, part of the glycerine will dis-
`solve in the metallic soap and someofthis glycerine will
`react with the metallic soap to produce metal oxide,
`triglyceride, a certain amount of mono- and di-glyce-
`ride and some water. On theother hand,it is wasteful to
`use more water than is necessary and, in addition, the
`use of a great excess of water leads to-a loweryield of
`metallic soap for a given vessel size.
`Even when the amount of water used is equal to the
`amount of glycerine produced the metallic soap that is
`separated after the reaction contains over 3% of glycer-
`ides. When the amountof wateris reduced even further,
`so that no excess over the stoichiometric amount is
`present, the reaction goes only.to about 80% of comple-
`tion, as indicated by the presence of approximately
`
`60
`
`65
`
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`
`4,316,852
`
`— 0
`
`20
`
`25
`
`40
`
`45
`
`10
`20%, by weight, of: glycerides in the metallic soap: In
`both instances,
`there is also a substantial amount of
`glycerine dissolved in the soap. A productofsufficient
`purity for commercial applications can be obtained if
`the.amount of water corresponds to about 4 times the
`stoichiometric amount of glycerine produced on com-
`pletion of the reaction. It is well known that many me-
`tallic soaps are readily hydrolyzed, at elevated tempera-
`tures, to metallic ‘oxide and fatty acid. It is therefore
`‘surprising that; considering. the large amount of water
`presentin the process, an insignificant amountof hydro-
`lysis occurs. Generally,it is appropriate to have a con-
`tent of water in the reaction mixture at least equal to,
`preferably about 2 to about 10, more preferably about 2
`to about 7, and mostpreferably about 3 to 5 times the
`stoichiometric amount of glycerine produced on com-
`pletion of the reaction.
`In another respect, the amount of water employedis
`important, because, as previously discussed, it affects
`the specific gravity of the solution ofglycerine in water.
`This specific gravity must be significantly different
`from that of the molten metallic soap if a substantially
`complete separation of the molten metallic soap from
`the glycerine in water solution to producelayers, is to
`be achieved.
`The presence of only a small amountof glycerinein
`the product metallic soap is deleterious because, at ele-
`vated temperatures, the glycerine reacts with the metal-
`lic soap to produce water, metal oxide and glycerides.
`However,it is very difficult, and perhaps impossible, to
`completely eliminate the presence of trace amounts of
`glycerine in the soap.
`The reaction temperature should exceed the melting
`point of the metallic soap to be formed; otherwise, the
`reaction will not go nearly to completion: The higher
`the temperature, the faster the reaction occurs and the
`reaction rate increases by approximately 50% for every
`10° C. increase in reaction temperature. On the other
`hand, high temperatures, such as those well in excess of
`200° C., should be avoided because they frequently
`cause discolouration ofthe metallic soap. Furthermore,
`high temperatureslead to build-up of high pressures in
`the reactor which in turn necessitate the use of other-
`wise unnecessary expensive production equipment.
`In the case wherezincstearate is being manufactured,
`it has been foundthat at a reaction temperature of 130°
`C., the time required to complete the reaction is approx-
`imately 6 hours and, at a temperature of 220° C., this
`time is reduced to less than 1 hour. If the reaction is
`carried out for too short a time, the reaction will be
`incomplete. However, if it is carried out for an exces-
`sively long time, discolouration may occur.
`The best reaction temperature is therefore one ‘thatis
`as high as possible, but with the practical upperlimit
`being about 250° C. becauseofthe possibility of thermal
`decomposition. Further, as indicated above high reac-
`tion temperatures result in the build up of high pres-
`sures. Water vapour pressure increases rapidly with
`temperature: at 150° C., the vapour pressure is 54 psig
`(pounds per square inch gauge); at 175° C., it is 115
`psig.; at 185° C., it is 148 psig.; at 200° C., it is 211 psig.;
`at 220° C., it is 322 psig. and at 250° C.,it is 562 psig.;
`clearly, therefore, the practical reaction temperature
`will be partly determined by the ability of the reaction
`vessel employed to withstand the high pressuresassoci-
`ated with high reaction temperature.
`A reaction temperature of about 100° C. to about 250°
`C., preferably about 125° C. to 200° C. and mostprefer-
`
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`
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`

`4,316,852
`
`5
`
`10
`
`25
`
`li
`12
`ably about 175° C. to 195° C., and a reaction.time of 0.5
`has been completed and whenit is desired to separate
`to 10 hours, preferably about 2 to 5 hours, are found
`the molten metallic soap from the solution of glycerine
`suitable for most purposes, in order to obtain a satisfac-
`and water. However,
`the creation of such a higher
`tory rate of reaction while avoiding discolouration of
`pressure during