US2287849A - Antistick surface coating - Google Patents

Description

' Patented June 30, 1942 UNITED STATES PATENT OFFICE Clarence Walter Wilson, Norco,

to California Fruit Growers Exchang Calif., assignor e, Los,

Angeles, Calif, a corporation of California No Drawing.

Application August 17, 1940, Serial No. 353,125

14 Claims. (Cl. ans-s4) V This invention relates to the coating ofsurfaces to reduce the tendency of those surfaces to stick to other surfaces. Uses for the invention arise particularly with such materials as asphalt, bitumen, and more solid pitches. It is also applicable in the handling of a molasses product known in the trade as hard molasses, and which is in reality a highly concentrated molasses which has some physical characteristics much like a fairly high melting asphalt. Tacky rubber l es e surfaces also present the problem of stickiness.

Such materials as "asphalt, bitumen, highly concentrated molasses, and tacky rubber present .the problem of sticky surfaces in the handling and shipment of the substances themselves.

I have found that it is possible to produce a non-sticky surface which can be used in conjunction with the above mentioned adhesive substances and which will permit other substances or other articles to be readily enough removed from the surfaces of said substances to produce commercial satisfaction in the handling of the substances. I do this by the utilization of the aqueous dispersions of materials commonly referred to as pectates. r

Accordingly, an object of my invention is the production of relatively non-sticky surfaces for use in conjunction with the otherwise adhesive surfaces of asphalt, bitumen, more solid pitches,

highhr concentrated molasses, tacky rubber, and 80 analagous substances."

In applying the invention to the handling and shipping of the above substances, it may be desirable to employ containers and under present practices to coat the containers. For example, bags may be formed from heavy paper and then filled with the substance which has been rendered fluid as by the application of heat. In such practice it is, of course, necessary to remove the paper container from the solidified contents before the contents can be again heated or otherwise utilized. Of the substances specifically mentioned above, rubber, of course, will not ordinarily in commercial practice be rendered fluid by the use of heat.

Now the surface of an ordinary heavy paper which is available and useful for this purpose actually presents a multitude of projecting fibers, and, if the surface of the paper he not coated, the

35 dispersion of, say,

45 formed into to the use of a paper container, I employ crude v pectated pulp of the type described in my Patent 2,132,065. I make an aqueous dispersion from the crude pectated pulp as follows:

The desired quantity of the crude pectafgd pulp is mixed with approximately '7 0 of its weight of NBAPiO'l and approximately 5% of its weight of flazafia. This mixture is stirred into an appropfimuantity of hot, and preferably boiling water to give the concentration of pectate he dispersion. I prefer to boil the dispersion with rapid agitation for five minutes. The dispersion is then ready for use or may preferably be somewhat cooled before application.

It may be applied to the surface of the container or to the surface of the material of which the container is to be formed, in any desired manner, as by means of spraying, dipping, brushing or rolling.

The amount of material to be applied and the square feet of paper, and I may suitably employ as much as one and one-half to two pounds per 1000 square feet. The upper limit will ordinarily be a matter of economics.

When applying the pectate dispersion to a surface of paper or the like as by means of rolls, I have found that a dispersion containing'2% of the pectate by weight flows on very readily, and gives a uniformly coated surface, and dries to produce a thin coating. On the other hand, a

6% by weight of pectate produces a coating of a thickness desired under some circumstances. With such a dispersion, I may preferably employ or more of common soap based on the final batch, or other surface tension 40 depressant in' suitable proportions. The soap or other surface tension depressant is added after the pectate has been dispersed. These are not essential when coating paper.

After drying, the coated material may be the interior, to receive the molten asphalt, or 'the like. It will be found that such containers can be removed or stripped from the solidified contents satisfactorily.

fibers become thoroughly entrapped in the molten Obviously the term P 1 the P p s s 1 my invention is equivalent to any substance prematerial, and when the material is solidified, it is found to be practically impossible to remove the paper relatively completely, as must be done for satisfactory commercial practice.

e. V applying my invention in preferred form 56 Numerous attempts and suggestions have been senting a similar surface which it is desired to have readily removable from the asphalt or the containers with the coated side on- I known. These vary somewhat in their properties.

However, so far as I am at present aware, they all present some degree of utility in connection with the present invention. Two distinctly different types of ectates are: the type made by 15 gthe process d'closed in Huber Patent No.

' gentle stirring a fine stream of r nir ieral acid, such as Slllfllljg. The coagulum is strained off and 30 washed until the wash water shows no trace of the acid, after which it is dried at not over 70 C. and ground to produce the finished product.

The crude pectated pulp described in my Patent 2,132,065 is produced substantially as fol- 5 lows:

Citrus pulp is finely ground and thoroughly washed'withwater. It is then suspended in suffi cient water to give a fluid mass. Soda ash is added with stirring to make the liquid just alkaline to phenolphathalein' (about pH 8.5). The pulp is left in contact with the soda ash for about twelve hours, preferably at'about 25 C. Any free liquor is drained off and the pectated pulp is thoroughly washed with water, dewatered, 4.1

ground, and dried.

The dried or undried ctated pulp may be dis-- persed mm by ad fig I00 parts of it (dry basis), 12 parts of trisodium phosphg,te and 1.2 parts of sodium hydroxide to 20mm of boil- 5O ing water. e suspension is well agitated and Eept 'ust alkaline to phenolphthalein for, say, fifteen minutes. It is then ready for use as such, or may be diluted.

Purified fibrous" pectates may be prepared 55 from the above dispersion by filtration to remove pulp particles, and precipitating with an approximately equal volume of alcohol.

The alkali pectates obtained by the above process are fibrous in appearance, in contrast to the co non-fibrous character of pectates made by other processes, and I refer to them as fibrous pectates. P

It will be obvious to those skilled in the art that other specific phosphates and other specific 05 alkali'es may be used in place of the particular ones mentioned hereinabove for dispersion purposes.

For the purpose of the present invention I prefer for commercial and economic reasons to 70 utilize the fibrous type of pectate, made as disclosed in my Patent No. 2,132,065, and in particular the crudefibrous pectated pulp therein described. This material possesses ease and cheapness of manufacture, and reliability of ac- 7 tion in connection with the present invention, which I regard as outstanding advantages.

As indicated above, this invention. is useful under circumstances where it may be desired to prevent asphalt, bitumen, tacky rubber, and the like surfaces from sticking or to reduce the tendency to do so; and the aqueous dispersion may be applied to the desired surfaces in a variety of ways, as by spraying it upon articles already coated with asphalt, or by dipping them in the aqueous dispersion.

When bodies composed of tacky rubber or having tacky rubber surfaces ore subjected to serious deformation, the surface c ating herein de-- scribed may undergo suflicient cracking to permit the bodies to stick together to a considerable extent.

Asphalt and bitumen are very commonly em ployed for the purpose of coating a variety. of objects where a heavy and resistant protective coating is required. An example is the coating of pipes which may be exposed to many different conditions. In applying the invention to the coating of such objects I may either spray the pectate dispersion on the coated object or dip the object after coating into the pectate dispersion, depending upon the size, weight, and shape of the article and convenience in handling. When the dispersion is to be applied directly to the surface of the asphalt, bitumen, or the like, I find it preferable to employ soap or other suitable surface tension' depressant in the manner and amount hereinabove described in order to obtain satisfactory spreading of the fluid film over the asphalt or other substance.

Having thus described my invention in such surfaces of asphalt, bitumen, and the like,'

which comprises placing in immediate juxtaposition with the surface a coating containing effective quantities of pectate.

2. A method of rendering articles coated with asphalt, bitumen, and the like, non-sticky .at the surface, comprising applying to the surface a coating containing efiective quantities of pectate.

3. In the manufacture of transportation packages of asphalt, bitumen,.and the like,'the step comprising coating at least the interior surface of the material of the container with a coating containing quantities of pectate sufiicient to permit ready separation of the container from the contents thereof.

4. As a new article of manufacture, a body having a surface composed of asphalt,, bitumen, tacky rubber, or the like, the surface being coated with acoating containing effective quantities of pectate, whereby the surface is rendered relatively non-sticky.

5. A transportation package comprised of asphalt, bitumen, highly concentrated molasses, or the like, within a removable container, and a coating on the interior of the container comprised of pectate, which perfects the transportation package in rendering the container readily removable.

6. As a new article of manufacture a container formed from paper, or the like, and adapted for use'in the handling of asphalt, bitumen, highly concentrated molasses, and like substances, said container having on its interior creases 3 surface a coating containing effective quantities of pectate, which perfects the container for the use designated. a

7. As a new article of manufacture paper adapted for use as a container for asphalt, bi-

tumen, highly concentrated molasses, and like substances, and having a coating containing pectate in amounts not less than about pound of pectate per 1000 square feet of paper, which perfects the paper for use in a container for asphalt. bitumen, highly concentrated molasses, and like substances, and permits ready separation of a container made. from said paper from the contents thereof.

8. A method of minimizingadherence between sticky substances such as asphalt, bitumen, and

the like. and a material such as paper and the having an outer normally sticky surface consisting of asphalt, bitumen, or the like, which comprises applying to the surface of such articlean aqueous dispersion of pectate, the dispersion includins a surface tension reducing agent.

11. A method of rendering non-sticky articles having an outer normally sticky surface consisting of asphalt, bitumen, or the like, which comprises applying to the surface of such article an aqueous dispersion'of pectate to form a coating containing not less than one-half pound of pectate per thousand square feet of article surface.

12. A method of rendering non-sticky articles having an outer normally sticky surface consisting of asphalt, bitumen, or the like, which comprises applying to the surface of such article an aqueous dispersion of pectate, thedispersion. including a surface-tension reducing agent, to form a coating containing not less .than one-half pound of pectate per thousand square feet of article surface.

13. A method of producing relativeiy nonsticky surfaces of asphalt, bitumen, and, the like,

which, comprises placing in immediate juxtaposition with the surface a coating containing effective quantities of fibrous pectatee 14. As va new article of manufacture, abody having a surface composed of asphalt, bitumen,-

tacky rubber, or the like, the surface being coated with a coating containing eflective quantities v of fibrous pectate, whereby the surface is rendered relatively non-sticky.

CLARENCE WALTER WILSON.