US2758100A - Dairy wax composition - Google Patents

Description

Aug. 7, 1956 R, M. BAILLY Erm.

DAIRY WAX COMPOSITION Filed Jan. 2, 1952 @NH Als GN DNI, Q zmm\.x. a O dmku Ai .dmljU A| m F .mf @j :35. @NH N dmhiu Al dmlj@ nm@ 10@ Pay/J0@ mw ON\= ON.: s X42 m: 4 NIEUW mnzov .faQ/J0@ .Sr/J0@ amr/D2@ Al l\ x43 l 45j |:O mm k SAL.: m* 0 J 3Qmmd i Hm om N N# T 1 A@ FQ@ 23N k mzoN mjoN Nm @dmrlzu Al .UZJJEU Alm Amm 330mm :l D

.www Al Amm 5| OM my AI (qm J @922mg a @mj P1930@ Al L l.. m mm lio United States Patent O DAIRY WAX COMPOSITION Randolph M. Bailly, Little Silver, and Harold F. Hitchcox,

Cranford, N. J., assignors to Esso Research and Engiueermg Company, a corporation of Delaware Application January 2, 1952, Serial No. 264,522 8 Claims. (Cl. 2611-285) This invention relates to a new and improved wax composition and more particularly relates to the use of such a composition in the coating of paperboard milk containers and the like. The invention is particularly concerned with the production of a high quality dairy wax composition produced by utilizing a relatively narrow cut paraffin wax fraction in conjunction with a relatively small amount of a material selected from the class consisting of microcrystalline waxes and polyethylene. The present application is a continuation-in-part of Serial No. 202,443, led December 22, 1950, entitled Improved Dairy Wax Composition, for Bailly et al., and now abandoned.

One of the objects of the invention is to coat or impregnate paperboard, particularly milk containers, with a wax composition having improved leakage resistance qualities in regard to the prevention of leakage through the cartons or liquid absorption into the cartons. Other objects of the invention will be set forth in the following description which illustrates preferred embodiments thereof, it being understood that the above statements of objects is made to explain the same without limiting it in any manner.

In the refining of hydrocarbon oils such as petroleum oils, it is known to segregate parain waxes from socalled parain distillates, waxy lubes and the like. The segregation of these waxes is secured by a number of processes. For example, it is known to chill the selected wax containing fraction n order to secure crystallization of the wax and to remove the wax crystals from the oil by filtering, centrifuging and the like. It is also known to use various dewaxing solvents such as liquid normally gaseous hydrocarbons, such as propane, as well as other solvents, such as methyl-ethyl ketone and the like. It is also known to utilize in .dewaxing operations solvent mixtures wherein one solvent comprises a wax precipitating solvent while the other comprises a solvent having a high solubility for oil. A solvent mixture of this character, for example, comprises 60% by volume of toluene and 40% by volume of methyl-ethyl ketone. In utilizing a mixture of this character, it has been the practice to add the mixture in toto or incrementally to the waxy distillate as it is being chilled. In dewaxing operations, it is also known to use various lter aids and other agents in order to render the dewaxing and iltering operations more eiicient.

The wax segregated from the hydrocarbon oil, usually termed slack wax, contains from about 10% to 40% of 2,758,100 Patented Aug. 7, 1956 oil. The slack wax is refined usually by conventional sweating to produce crude scale wax in a manner to reduce the oil content to less than about 5% by weight. The slack wax may be distilled to obtain the desired boil ing range wax prior to sweating, if desired. This crude scale wax generally has an oil contentof about 2% to 3% by weight. In order to remove this oil from the scale wax to produce a refined wax having an oil content below about .5%, usually below about .3 various pro-` cedures have been proposed and employed.'

It is also known in the art to segregate microcrystalline waxes from residual oils. These microcrystalline waxes are of a relatively high melting point and of different crystalline structure. The microcrystalline or petrolatum waxes may be prepared from any of the parathn or mixedl base crude oils. The undistilled residue may be treated with sulfuric acid and neutralized to remove the tarry matter and unsaturated hydrocarbons. The undistilled residue also may be deasphalted. The treated stock, containing a fairly high percentage of wax, as evidenced by' a very high pour point, may be dewaxed by blending with a dewaxing solvent, such as propane, methyl ethyl ketonebenzol, or petroleum naphtha and chilled, and liltered or centrifuged to separate the petrolatum wax from the oil solution.

This deoiling operation produces a wax containing some oil and solvent. The wax after removal of the solvent has a melting point of from about to 180 F. The wax may be again put in solution with more solvent or naphtha and chilled and filtered or recentrifuged to further reduce the oil content. The wax which separates in either of these operations is referred to as crude petrolatum wax. The wax separated in the second deoiling process after stripping to remove solvent is fairly dry and of a low oil content.y This wax should not be confused with petroleum jellies which contain large amounts of oil. The crude petrolatum wax may be again put into solution with naphtha and filtered through clay or an equivalent material in order to improve its color. The clay filtered solution is distilled to remove the naphtha, the residue be ing a refined petrolatum wax having a melting point within the range of about 140 to 180 F. The source of the crude oil and the oil content of the retned microcrystalline product will alfect the melting point of the final wax product. The refined petrolatum wax, sometimes called amorphous wax, is of very small crystal structure.

The hereinbefore mentioned crude petrolatum wax may be fractionated into petrolatum waxes having melting points within the range of 140 F. to 180 F. Usually this separation is eiected by fractional precipitation from ketone, propane or naphtha solutions. The terms petrolatum waxes or microcrystalline waxes are used in this application to cover the residual type petroleum waxes of Very small crystalline structure, and having melting points above aboutv F. and oil contents in the range of about l to 10%.

ln the paperboard carton art, moistureproofness and, where desired, liquidproofness have hitherto been attained through the use of parathn wax. Parathn, while inexpensive, has certain disadvantages. It is the general practice to apply the parain either to iinished container blanks or to finished and erected containers, closed on one end.

Aamiamo Paratlnformsa `relatively fragile coating subject to disruptiontwhen .the .paperboard is bent.

There has not hitherto been a satisfactory, cheap, coated paperboard for the manufacture of cartons or containers in which an interior coating provided the desired greaseand liquid-proofness, as hereinafter explained. The desirable qualities of such a product are these:

1. Mostureand lqudproofness.-The coating should impart to the board a suiciently high degree of resistance to penetration by (1) water vapor to prevent food products from drying out and becoming stale too rapidly and (2) liquids to insure satisfactory delivery to the consumer.

Y, 2. Freedom frompdor and.tQxic ity.-Itis obvious that a coating Afor foodstuff containers ,should possess no odor nr any ,degree 0f toxicity.

.3.; Arziglitnessf'lfhis ,quality is .to be distinguished from resistance tov moistureand liquids. The term airtightness isvr usedto mean the quality of blocking odors, whetherthe purpose be the protection of the. contents of the container from contamination by foreign odors lor thc prevention of loss of aromatic values by the contents of the container.

4. Low cost.'-Both the coating composition and its method, of application4 shouldbesuch as to permit the lowestpossible cost, since food products are distributed in large volume and are bulky in relation to jdollar value. Hence, protection must be attained at the mosteconomical level possible so as` not` to kmake it necessary to raise the Selling price.

5."Handleability--The coating imposed Aupon the paperboard should not be such as to interfere with theA normal operations 4of producingcartons and containers. It must neither be `so fragile as to bedisrupted by normal handling operations, normust it be tacky so as to make sheet separation difficult.

6..lmlzact.strength.f-Impact strength, is a very important index to the suitability of waxes as coating materials. High impact strength, i., e. high resistance to deformation or crackingl on impact, is related to the-ability of the wax tojwithstand rough handling and chipping.

7.Leakage resistance tesa-This test was developed to. vdetermine the ability of a wax to preventv leakagefrom paperboard milk cartons. vIt is basedon a measurement of Ythe percentage of ,leaking cartons which .were subjected' to a standardized impact by dropping on a bottom corner. A large s arrlple size is chosento increase the accuracy, of the test by reducing the probable error resulting from` asmall percentage of non-standardquality cartons produced by;the. machine. .This testis carried out as follows:

(.a) :100.cartons which have been conditioned at least 2.4,hours at 73 F. a-nd 50% relativehurnidity. arecoated andt-,tilled-,with 40 F. .water on ,a standardmilk carton machinein the normal manner.

V(b.) .Thesel cartonsare storedlliours at140 F.

`(c) After storage, the cartons. are. individually. dropped 5 inches on'l a standard corner. `A dcvice having a hinged lever armand. tripping mechanism is4 used tol providestandard.. drops.

(d) .'Cartonsthat.donotleakwhen dropped are stored for 24 hours at 40 F. vand leakers noted. 'Any observed leakage is; suticient to. callthe carton a leakerf (e) The bottom gluingof all cartonsarecheckedand anycartons wit-h superioror inferior-to standard bottoms are noted and their durability yratings discarded.

(f), .'[henumberof cartons that-leakisexpressed as percentage. of the group Iand reportedas ;per.cent leakers.

8. Storage testa-701;) Absorption test,at,7`3 .Rf-Five empty, coated cartons are indiv'idual1-v.vveighecblled.with a ,1%. solutionof lactic acid, colored-with methylene-blue, and .stored at 73 F. for 72 hours. At the end .of-'this period` any .'lealcers Vare noted .and fthe bulge (average :of

`.to the-nearest j/32nd of an inch. The cartons are then drained, shaken out well, and re-weighed to determine the amount of liquid absorbed.

(b) Absorption test at 40 Fr-Ths test is carried out following the same procedure as described above except for temperature.

In order to secure a wax composition having desirable properties as enumerated above, various processes and compositions have been suggested. For example, it has been suggested that blends of paraffin waxes with microcrystalline waxes be made which compositions have improved tensile strengths which are desirable. However, it has now been discovered that the impact strength of wax coatings can be greatly increased by blending a narrow cut paraffin wax with a small amount of microcrystalline wax or with polyethylene or both. The microcrystalline wax is added in amounts from about 1% to 10% by weight, preferably from about 2% to 5%, while the polyethylene is addedin amounts between 0.1 and 3% by weight.

The lpolyethylene suitably has a'molecular'weight between about 4,000 to 22,000. A preferred molecular weight is in the range from about 10,000 to 14,000.. With both materials are added, the proportions, based on the narrow cut wax, may be 1-l0% ofthe microwax and 0.1 to 3 of the polyethylene. The parain wax to be suitable for this invention must have a boiling point spread not greaterthan about 50 to 90 2F., andpreferably'not greater than 40 to 60 F., between the 5% tot95% distillation points at l0 mm. pressure. The fact that a narrow cut .paratin wax gives an excellent coating having' high impact strength is surprising since the physicalinspections lead to the expectation of poor performance. The narrow cut waxes are brittle and have a veryv low exibility.

The ypresent invention will be more fully yappreciated by. reference to the drawing illustrating one -embodiment of the same. Referring specifically to -thedrawing, a-waxy crudeY oil is introduced into distillation zonel by means of feed line 2. TemperatureV and pressure conditions` in zone 1 are adapted to remove overhead by means of lines 3 .and4 to ylow boiling hydrocarbon fractions. A waxy distillate fraction is removed as a sidestream by means of line 5, while a residual oil is removed by means of linc6.

The waxy distillate iiows through a chillingy zone 7'which mayk comprise a plurality of chilling stages lwherein the temperature lof the waxy distillatel is progressively'rcduccd. AV typicalL operation is to introduce the feed oil intoran initial chilling stage at a temperature of Yabout 130'F.; to introduce the feed oil into the second.chillingstage at a temperature of about F.; to introduce the feed'roil to the third chilling stage at atemperature of about'-60' F.; to introduce the feed oilto the-fourth chilling stage ataa temperature of about 25 F. `and to chill'thevsame'in the fourth chilling stage toa temperature in theerange from-about -11'0 to -l-10v F. AThe operation of the respective chilling` stages may be varied lappreeiably'fand.either direct or indirect chilling means utilized. .Fort .purposes of illustration, it is assumed thata solvent mixture isy usedand that the wax-precipitant comprises methylfethylketone and that the aromatic solvent havingv ahjghsolubility for oil comprises toluene. Itis also assumed that 3 to'4 volumes of total. solvent mixtureis `utilized per volumefof waxy oil being dewaxed. Thesolvent mixture comprises 75% by volume of methyl-ethylketone-and 25% by volume of toluene.

The entire mixture comprising oily.constituents, crystallized wax constituents, toluene fandrnethyl-ethyl ketone, after chillingris held atthe filteringy temperaturefandpassed to filtering zone 8 wherein the solidwax particles .are segregated from the oily constituentsby :any suitable tiltering; or separationmeans. The/filtering zonemay comprise; drum iilters,rplate: and frame presses, centrifuges or suitable equivalent equipment for the separationpf the precipitated waxy constituents from theJ oily constituents.

The oil and a portion of the solvent is removed from zone 8 by means of line 9 and the wax cake washed with a wash solvent introduced into ltering zone 8 by means 0f line 10 Slack wax and solvent are removed from zone 8 by means of line 11 and passed to a distillation zone 12 wherein a separation is made between the wax and the solvent. Itis to be understood that other means of separating the solvent from the wax may be utilized if desirable.

The wax substantially free of solvent is removed from separation zone 12 by means of line 13. The solvent mixture comprising methyl-ethyl ketone and toluene is removed overhead from zone 12 by means of line 14 and preferably recycled to the system. The oil-solvent mixture removed from ltering zone 8 by means of line 9 is introduced into a distillation zone wherein a separation is made between the oily constituents and the solvent mixture.

While the drawing illustrates a solvent dewaxing operation with respect to the production of the slack wax, it is to be understood that the waxy constituents may also be separated in a conventional plate-and-frame pressing operation. The slack Wax is further refined to crude scale Wax in zone 15, which comprises a conventional sweating operation, or solvent deoiling operation, 0r the like. The oil removed from zone 15 by means of line 36 may preferably be recycled to zone 7. The scale wax is removed from zone 15 by means of line 35 and may be further relined by treatment With sulfuric acid or fullers earth, bauxite or other absorbent materials, or by hydrogenation under mild treating conditions.

The crude scale wax removed by means of line 35 is either sweated or solvent deoiled to produce aretined wax having an oil content below about .5%, preferably below about .3% For the purpose of illustration, solvent is introduced by means of line 50. The mixture is introduced into zone 51 wherein the oil content of the wax is reduced so as to produce a refined wax. Solvent is removed by means of line 52 while the refined wax is removed by means of line 53.

This Wax is introduced into distillation zone 54 where the same is distilled preferably under pressure of about l0 mm. A discard cut comprising gas oil constituents and contaminants is removed overhead by means of line 55. A low boiling cut is removed by means of line 56, an intermediate or heart cut is removed by means of line 57, While a high boiling cut is removed by means of line 58.

While the distillation range of the refined wax introduced into distillation zone 51 may vary somewhat depending upon the character and the source of the relined wax, a typical parain refined wax distillation range at 10 mm. pressure is as follows:

Temperature, F.

Typical inspections of the low boiling fraction, of the intermediate fraction and of the high boiling fraction at 10 rnm. pressure as produced in distillation zone 54 are as follows:

Retined Wax Fraction Low Heart High Boiling Cut Boiling In accordance with the broad concept of the present invention microcrystalline Wax or polyethylene is added to these relatively narrow boiling fractions. In accordance with a more specific adaptation of the present invention it is preferredy that the microcrystalline wax or polyethylene be added either to the heart cut or the low boiling cut. A particularly desirable wax composition is secured by adding polyethylene or microcrystalline Wax to the low boiling fraction, i. e., a fraction having 5% distilled at l0 mm. pressure at a temperature of about 430 to 440 F., and having 95% distilled at a temperature from about 475 F. to 485 F.

The present invention may be more fully appreciated by the following examples illustrating the same.

EXAMPLE l Two commercial dairy wax compositions characterized by containing 2% of microcrystalline wax were compared with wax compositions of the present invention. The results of the test are as follows:

Dairy wax evaluations Commercial Narrow Cut 4 Narrow Cut i Dairy Wax #l #2 Wax A B No ad- |5% N o ad- +5% ditive Micro ditive Micro B. P. Spread -A l?.

(Q5-5% Pts. at 10 mm.) l 129 l 112 80 65 Wax Consumption lbs/1,000 cartons. 33.0 33. 2 35. 2 35.2 34. 2 34. 4 Percent; Leakers 2... 71 2 16 5 3 v 40 F. Storage 3..-.- Satisfactory Unsat. Sat. Unsat. Sat. 73 F. Storage 3-...- Satisfactory Unsat. Sat. Unsat. Sat.

-at both 40 F. and 73 F I Low honing fractions'. 5% distilled at 420 F. to 440 F.

The above data show the surprising fact that the narrow cut paraffin wax itself is highly superior to any commercial wax with regard to the number of leaking cartons obtained after submitting to the test although the storage characteristics are very poor. The data also shows that, While not quite as good as the wax alone as regards percent leakers, the blend of the narrow cut wax #l F. AF. 5-9% pt.) with microcrystalline wax is still much superior to the commercial waxes and is satisfactory in storage. The narrow cut wax #2 (65 F. AF. 5-95% pt.) is also far superior to the commercial dairy waxes in leakage resistance although storage is again very poor. However, the addition of microcrystalline wax provides a blend with equally good leakage resistance and fully satisfactory storage characteristics.

Other wax blends were prepared in accordance with the present invention and compared to two of the best dairy wax compositionscontaining about 2% microcry-stalline wax. The results are illustrated in the following table:

composition which comprises blending a refined paran waxwith about 0.1 to 10% by weight of polyethylene Commercial Narrow Out #l Narrow Cut #2 Dairy Wax Wax +27 +57 +27 +57 +107 ggi 120070 A B Alone Micr Mie?) Alone Micfo Micra@ Mmr M. W MI W.

Polyeth l9% ylene Micro 13. P. s read -A F.' 95-5 t. at 10mm.) of

base viix l 7 l 129 112 80 80 80 65 65 65 Wax Consumption, lbs/1,000 cartons 33.0 33. 2 33. 8 33. 2 33. 0 35. 3 34. 34. 4 33.0 34. 3 34 PercentY Leakers I; i .i v71 69 3 Y 4 16 5 1 3 3 5 7 40 F. Storage with 17 aetic ci o ut' Acid Absorption, labs/1,000 cartons... 9 8 13 15.0 10. 3 15. 9 8.0 6.0 7. 0 7 Bulge, Maz" 2 2 6 8 2 9 1 2 1 2 1 730 1iQvaall Storatg, i.(yatI-irlig.. a...lut S S U U S U' S S S S S orage wi ac ic c o u on: Acid Absorption, labs/100 cartons 16 12 18 16. 8 12 20. 9 10. 9 11 11 8 Bulge, Mn 7 4 `10 7 4 13 4 6 4 5 3 Overall Storage Rating S S U U S U S S S S S S--Satisactory- U-Unsatisfaetory.

What is claimed is:

1. Process for the preparation of an improved vwax composition which comprises preparing a refined paraiiin wax having an oil content below about 0.5%, segregating from said parain wax a narrow boiling fraction having a boiling point at l0 mm. of about 430 to about 440 F. and a boiling point spread of not more than 90F., between the 5% and 95% points in-a 10 mm. distillation, and adding to -said narrow boiling fraction about 0.1% to 10% by weight of a material selectcdfrom the class of mircrocrystalline wax, polyethylene having a molecular weight of about 4,000 to 22,000 and mixtures thereof.

2. The process defined by claim 1 in which said added material constitutes polyethylene.

3. The process defined by claim 2 in which said narrow boiling fraction has a nboiling point spread of not more than about 50 F. between the 5% and 95% points in a 10 mm. distillation.

4. An improved wax composition consisting essentially of a narrow boiling point rened'parafn wax fraction having a boiling pointsprcad of not .more than 90 F. between the 5% and 95 points in a 10 mm. distillation, having a 5% point at about 430 to about '440 F. containing about 0.1% to 10% by weight of' a .material selected from the classofmicrocrystalline wax, polyethylene having a molecular Weight of about-4,000'to 22,000 and mixtures thereof.

5. The wax composition defined byclaim 4 in which the said -material contained in the parain wax fraction constitutes polyethylene.

6. The composition defined by claim '4 in which the `said narrow boiling wax fraction hasta boiling point spread of not more than about 50"F. between' the 5% and 95% points lin a 10 mm. distillation.

7. In a process for the preparation of an improvedA wax having a molecular weight of about 4,000 to 22,000, the improvement which comprises blending said polyethylene in a narrow boiling relined paraffin wax fraction having a boiling point spread of not more than F. between the 5%\and 95% points in a 10 mm. distillation, said fraction having a 5% point of about 430 to about 440 F.

8. ln a wax composition comprising a blend of a rened parafn Awax and about 0.1 to 10% of polyethylene having a molecular weight of about 4,000 to 22,000, the improvement which comprises employing for said rened paraffin wax a narrow boiling fraction having a boiling point spread of not more than 90 F. between the 5% and points in a 10 mm. distillation, said fraction having a5% point of about 430 to about 440 F.

lReferences Cited in the file of this patent UNITED STATES PATENTS 1,937,518 Henderson et al. Dec. 5, 1933 2,102,516 Coster Dec. 14, 1937 2,348,689 Abrams et al. May 9, 1944 2,361,582 Adams et al. Oct. 31, 1944 2,373,634 Wagner et al Apr. 10, 1945 2,399,521 Tyler Apr. 30, 1946 2,443,221 Bergstein June 15, 1948 2,467,959 Bowman et al. Apr. 19, 1949 2,523,705 Lovell Sept. 26, 1950 2,559,645 Larsen July 10, 1951 2,582,037 Hyde Ian. 8, 1952 2,638,459 Bowman May 12, 1953 OTHER REFERENCES Polythene, E. I. du Pont de Nemours and Co., Inc.,

` Plastic Dept., April 1946, page 22.

Plastics (Chicago), December 1948, page 12.

Claims (1)

1. PROCESS FOR THE PREPARATION OF AN IMPROVED WAX COMPOSITION WHICH COMPRISES PREPARING A REFINED PARAFFIN WAX HAVING AN OIL CONTENT BELOW ABOUT 0.5%, SEGREGATING FROM SAID PARAFFIN WAX A NARROW BOILING FRACTION HAVING A 5% BOILING POINT AT 10MM. OF ABOUT 430 TO ABOUT 440* F. AND A BOILING POINT SPREAD OF NOT MORE THAN 90* F., BETWEEN THE 5% AND 95% POINT SPREAD OF NOT MORE THAN 90* F., AND ADDING TO SAID NARROW BOILING FRACTION ABOUT 0.1% TO 10% BY WEIGHT OF A MATERIAL SELECTED FROM THE CLASS OF MICROCRYSTALLINE WAX, POLYETHYLENE HAVING A MOLECULAR WEGHT OF ABOUT 4,000 TO 22,000 AND MIXTURES THEREOF.

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