US2085992A - Manufacture of asphalt - Google Patents

Description

Patented July 6, 1937 UNITED-STATES PATENT OFFICE MANUFACTURE OF ASPHAL-T Edwin F. Nelson, Chicago IIL, assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. Application August 20, 1932,

Serial No. 629,755

3 Claims. (01. 19674) respect to weathering and destructive agencies generally.

Asphalts of varying types suitable for use as binding material in road aggregates, as protective covering to prevent corrosion of pipes, as a saturant for roofing materials and felts, as insulating material in electrical work and for other purposes may be manufactured from raw hydrocarbon materials either by simple distillation with or without steam until the desired consistency is obtained or air may be introduced during the distilling operation to controllably oxidize the material under treatment and change the properties of the resultant product usually in the direction of increased melting point for a given consistency as determined by the penetra tion test... A further efiect of the oxidation is to increase the resistance of the product to weathering influences so that an oxidized asphalt may be looked upon in a sense as a preweathered material.

Ithas been further found by general experience that the disintegration of asphalt surfaces with the resultant crumbling and wearing is due to the combined action of light and air, neither light nor air alone exerting very great influence upon the decomposition of the asphalt. Since in the majority of cases asphalt employed either as road or roofing material must necessarily be exposed to light, any means for substantially preventing surface weathering will necessarily have to be alcng the line of preventing oxidation, and it is with means for preventing .or minimizing oxidation efiects on asphalts that the present invention is primarily concerned.

In one specific embodiment the invention comprises the use of certain materials known as anti-oxidants or inhibitors to reduce the tend ency of asphalts to oxidize. Materials which may be used for this purpose may be of 'a varied character as the exact nature of their action is not known although it is supposed to be due to their preferential absorption of oxygen which.

prevents or inhibits transfer of oxygen to the materials in which they are used to protect from its influence.

mentioned; naphthalene, tetralin, naphthols, naphthyl amines, phenanthrene, anthracene, dihydric phenols such as resorcinol and hydroquinone, trihydric'phenols such as pyrolgallol, oxyhydroquinone, and phloroglucinol. Other less commonly used materials which may also find application in special instances due to their easy availability, low cost or particular efi'ect in connection with special asphaltic materials are substances of such diverse character as aniline,

gum tragacanth, rosin oil, wood tars, preferably hardwood tar, tannin and others. p

It will be readily appreciated from a consideration of the varied chemical and physical character of the materials mentioned that their value will vary widely. In using these materials according to the present invention theymay be added to the residua during the process of asphalt manufacture therefrom, or they may be added subsequently to the finished asphalt. The amounts used will usually. vary from 0.1 to 2%, depending upon the nature of the residuum being treated, the type of product desired and the particular type of operation employed in the manufacture. manufacturing an asphalt suitable for use 'in aggregates for light service macadams to merely distill in the presence of steam until the desired consistency quired in such .sphalts being generally not over F. by the ball and ring method used by the United States Bureau of Roads laboratories. When asphalts of higher boiling points or melt points are desired which are suitable for use in the manufacture of tarpapers or felts or composite shingles, air blowing may be resorted to, either alone or in conjunction with steam. The

quality of air blown asphalts is subject to many employed, the nature of the product being parapparently related to the lack of ductility or It has been found shortness of the product. that the addition of small amounts of suitable anti-oxidants during the air blowing of cracked residua to produce high melting point asphalts provides a means of preventing the excessive oxidation due to accidental/ rises .of temperature and that they also .modify the nature of the final product in the direction of greater ductility or less brittleness due apparently to their effect in It may be quite sufiicient for reached, the melting point re-- conduct the operations at a temperature higher than that commonly employed without undue burning effects being noticed, the rate of reaction and the capacity of any given set of equipment,

being thereby increased.

A proper concept of the nature of the invention will indicate that it is one of wide applicability and that many examples of results of its use might be given. Since it may be used with any type of equipment or plant commonly used for the reduction of residua to produce asphalts, and since the general operations of asphalt manufacture are well known, it will not be necessary to describe them in detail, but it will besufiicient to mention that according to the process of the invention anti-oxidants of many kinds may be introduced at any stage of asphalt manufacture from cracked residua or at any time prior to or during their storage or use. A few examples of results which may be obtained along the line of stabilizing asphalts in respect to weathering influences will be suificient to dicate the economic value of the process.

In one instance comprised within the scope of the invention a cracked residuum produced as a by-product-in the manufacture of gasoline by cracking a California fuel oil may be reduced by air and steam combined with external heating to produce an asphalt suitable for use in saturating asbestos shingles. In ordinary operations wherein no anti-oxidizing material is used reduction may be carried on at an average temperature of approximately 480 F.'over a period of 15 to 20 hours to produce an asphalt having the following properties: i

Penetration 15 Melting point (ball and ring) F 200 Ductility cm 1 Solubility in 86 gravity paraflin naphtha When the same residuum is reduced to asphalt in the presence of 2% of anthracene the mean temperature of treatment may be allowed to rise' to 520 F. with a resultant decrease in the time necessary to produce the desired melting point Penetration 18 Melting point F- 200 Ductility cm 2. 1 Solubility in 86 paraffin naphtha '72 It will be immediately evident to those familiar with asphalts used for roofing properties that by the use of the process of the invention both an economy in time has resulted and also the production of an improved asphalt.

Other substances which may be employed to increase the stability of the asphalt product resulting from a treatment of cracked residual oils and which may be added during the treatment are resorcinol, pyrogallol, wood tar, and many others having the required properties.

It is to be particularly pointed out that depending upon conditions and results desired, the antioxidants or inhibitors may be added during the process of manufacture of the asphalt or subsequent thereto and that when added during the process of manufacture their boiling point should be above the temperature of treatment.

The use of .2 to .5% of the inhibitors or anti oxidants named such as alpha naphthol, anthracene, resorcinol, wood tar, hydroquinonc, have produced very marked results in improving the resistance to weathering, abrasion, cracking, hardening etc. of asphalts when employed for roofing purposes. paving and the like.

It is to be particularly pointed out that-these substances do notproduce strictly equivalent results but that the selection of any given antioxidant or inhibitor depends upon the conditlons of treatment and the results desired. Also that the method of treatment, that is, whether the inhibitor is to be added during the manufacture or subsequent thereto, will depend upon the conditions of treatment in the manufacture of the asphalt; for example, particularly when exposedto oxidation conditions during manufactureit is desired to have the inhibitor present, The inhibitor or anti-oxidant will prevent further deterioration at any time after addition of the same to the asphalt, whether in the process of manufacturing thesame or thereafter.

I claim as my invention:

1. A process of treating asphalt during the manufacture thereof by oxidation of cracked hydrocarbon residues which comprises incorporating therewith during the process of manufacture of the asphalt at elevated temperatures an antioxidant of a character and in'such quantity as to retard excessive oxidation.

2. In the manufacture of air blown asphalt from asphaltic material, the improvement which r