US2399521A - Wax compositions - Google Patents

Description

Watershed Apr. 30, 194 6 A Nll'ED STATES OFFICE WM COMPOSITIONS Walter S. Tyler, Philadelphia, Pa", assignor to Tide Water Associated Oil Company, ayonne, N. L a corporation of Delaware 1 o Drawing. Application March 9, i943, Serial No. 478,555

2 Elaims. (on. l96-ll49) The present invention relates to petroleum wax Stated in other words, the invention resides in compositions, and more particularly to the prowax compositions comprising blends of paraflin duction of petroleum wax of high tensile strength and amorphous wax sufllciently low in oil confrom paramn wax of low tensile strength. tent as to have tensile strengths greater than In the refining of lubricating oils from petrole- 5 those of the parafiln wax constituents alone. The um two general typ s of waxes are ordinarily re-' effect of small additions of solvent deoiled amormoved during the-refining procedure. These are phous wax upon the tensile strength of paraifin known, respectively, as crystalline or paraffin wax and alsothe detrimental effect on tensile wax and amorphous wax. Crystalline wax, which strength of the presence of small quantities of is characterized by a definite crystalline strucoil can be appreciated from the following tabuture and hard brittle texture, is obtained from lated comparative data. Both waxes shown were the distillate or wax distillate fraction resulting derived from Pennsylvania. crude. from distillation of the crude, by familiar deoiling methods such as chilling and sweating, Perkins and subsequent refining operations, to produce a. 131f Wax composition g, highly refined non-oily white product. Amor- @70 1?.

phous wax, as distinguished from the crystalline variety, is characterized by a higher boiling point, A Pmmn wax M, 11:;

5 r.) as usually a higher melting point and less brittleg-Egg g f ga a'glil g deified ness, and is derived from the residual crude disgo SampleB plus oIav'bfl m'smek 42 tillation fraction, 1, e., the traction from'which D sampleB "bright mck heavy lubricating oils are obtained, usually by blending t residual fraction with petruleum It can be readily seen from the table that the naphtha, nd centrifuging th resulting l ti addition of relatively small amounts of solvent to Separate oi The resulting oily wax, which deoiled amorphous wax greatly increases the tenmay contain 40% or more of oil, may be again 5119 strength of P m-fl Wax- Likewise the efiect put in naphtha solution and centriiuged to reof q e small quantities of oil in counteractin o further quantities f 11 The resulting the strengthening properties of solvent deoiled product, sometimes termed petrolatum wax, still wax is clearly evident. Addition of as little as contains considerable amounts of oil; generally 011 (Sample C) reduced the Strength 01 t e at least about 5% 1- 6% blend below that of the parailin wax. It has been reported that blends composed of Anflther important h a teri tic of the wax paraflin wax and petrolatum w derived as compositions of this invention is their relatively above described from certain mixed base crudes high Strengths at w temperatures for exhibit tensile strengths at r temperatures 3 ample, at temperatures from about 50 F. down materially greater than that of the paraflln wax 0 and Particularly after being p y alone. However, the addition to paramn wax chilled to said temp atures. Sudden chilling 0:? of petrolatum wax similarly d d from preparafiin wax results in formation of cracks with dominately si-emu base crudes such as Pennco q ea e of t u tu e, a in sylvania, od d t lt, in material such wax objectionable for such uses aswax coatcrease in tensile strength over that of the undin s for paper milk containers which are filled blended pamflln wax, with cold milk at 40 to F. and for waxing paper According to the present invention, it has been used in P c i qui k-frozen foods at about found that the tensile strengths of such aramn' 0 F. to about 10 F. The wax blends oi this waxes can be materially improved by incorporal- 5 nv i n r Particularly Suited or Such uses tion therein of solvent deoiled amorphous wax. inasmuch as they are characterized by reduced As distinguished from the centrifuge petrolatum cracking and by high strength when subjected to no solvent extractable amount of oil. These soliuge petrolatum wax referred to above; with powerful oil-solvent mixtures under conditions wax referred to hereinabove, which contains at chilling as shown in the following table. least 5 or 6% of oil, the solvent deoiled amorphous waxes of this invention may be considered sub- 50 Per cent 125 F. M. P. crystalline wax 10o stantially oil-tree in that they contain generally cent oiled smmphws W8! 0 vent deoiled waxes may be prepared by treatment of a suitable residual petroleum fraction or waxy material derived therefrom such as the centrieffective to extract or remove the oil from the wax.

such solvent deoiling methods and procedures This data indicates that incorporation of solwlll be described in more detail hereinbelow. vent deoiled amorphous wax in amounts as low as 1% will impsrt ample strength to crystalline wax at til-50 I". while 10% will provide satisfactory strength at i It will be understood that proportional amounts of solvent deoiled wax shown in the blends tabuiated hsreinsbove are merely illustrative of the invention but not limitative thereof. Other proportional nmounts may be used within the spirit and scope of the invention. For example, blends consisting of about 50% crystalline was and about 50% amorphous wax have exhibited uniform or even increasing tensile strengths at test temperatures of 0 F. over their strengths at 70 ii A particular advantage resides in the fact that the strengthening eflect is particularly marked at very low concentrations of solvent deoiled amorphous wax. For example, the addition I of as little as 0.1% of this amorphous wax 'improves the tensile strength of crystalline wax about 40% at room temperatures in certain instances.

The solvent deoiled amorphous wax employed in the above blends was produced from pet rolatum derived by centrifuge deoiling of a naphtha diluted residual lube oil fraction of Pennsylvania crude, by first solvent deoiling said petrolatum at -10 F. with a mixture consisting of 40% methyl ethyl ketone, 35% benzol and toluoi which resulted in a wax containing substantially no oily material of 25 F. pour point or lower, and then further solvent deoiling the resulting wax at 47 F. with :a similar mixture of solvents. In some instances, depending upon the particular wax source-andthe thoroughness of the solvent deoiling method used, a single solvent treatment will suillce. Generally, however, stronger blends will obtain when the amorphous wax constituent is produced by repeated solvent deoiling.

Likewise, the amorphous wax constituent may be produced from sources other than centrifuge petrolatum. Thus, for example, amorphous wax resulting from solvent deoiling of cylinder stool; is satisfactory.

The tensile strength test used is that described on pages 7 to 9 of U. S. Department of Interior, Bureau of Mines Bulletin No. 388, and consists briefly in applying a lineal pull to a test specimen of V square inch cross-sectional area of the wax to be tested, using as the testing machine the Perkins tester described in said Bulletin, and noting the force in pounds reached at failure of the test specimen. The procedure set forth the stated Bulletin was followed exactly except that tensile strengths at temperatures below 70 F.

were determined at the temperatures noted in the tables instead of at 70 F. on specimenswhich had been chilled from room temperature to the test temperatures by immersion in cold liquid immedlately prior to testing. All of the wax-blend specimens were prepared by melting together the designated weight proportions of crystalline and solvent deoiled amorphous wax, stirring to a uniform blend and solidifying in the dumbbellshaped molds shown in the mentioned Bulletin. The test specimens containing only crystalline wax were prepared by melting crystalline wax and then solidifying in the stated molds.

Another disadvantageous characteristic of crystalline wax which is eliminated by incorporation of solvent deoiled amorphous wax is that of "mottling," by which is meant formation of air or gas bubbles in the wax structure. This is particularly undesirable in wax used for candle making. Crystalline wax blends containing about 1% or more by weight of solvent deoiled amorphous wax do not exhibit mottling.

Other properties, desirable in crystalline wax compositions, such as color stability on heating and hardness, are not materially affected by the presence of the solvent deoiled amorphous wax constituent in tensile strength increasing proportions.

I claim:

1. A composition comprising oil-free crystalline parafllnic petroleum wax normally tending to crack'upon sudden chilling to sub-atmospheric temperatures and having incorporated therein an amount of solvent-deoiled, substantially oil-free parafllnic amorphous wax effective to inhibit said tendency of the crystalline wax to crack at said low temperatures, said amorphous wax being prepared from conventional centrifuge wax from which the usual 6-10% residual oil has been removed by powerful oil-solvent mixtures.

2. Method for inhibiting cracking of substantially oil-free crystalline petroleum wax upon sudden chilling to sub-atmospheric temperatures which comprises incorporating therein a minor portion of a solvent-deoiled amorphous wax derived from a predominantly parafllnic base crude, said amorphous wax being substantially oil-free.

WALTER 8 TYLER.