US1618572A - Cellulose product and method of making same - Google Patents

Description

Patented Feb. 22, 1927.

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HORACE H. CLARK, OF FAEMINGDALE, NEW JERSEY, ASSIGNOE TO CLARK FIBRE PRODUCTS CORPORATION, A CORPORATION OF DELAWARE.

CELLULOSE PRODUCT AND METHOD OF MAKING SAME.

No Drawin g;

in many ways to these; As an example of the best method of practising my invention at present known to me, I would proceed as In follows:

A bath is prepared offused zinc chloride brought-into solution with an amount of water sufficient. to give a reading of 72 Baum (for heavy liquids) at a temperature of 60 Fahrenheit and to this is added a small percentage of phosphorus oxychloride, preferably by taking about 10% of the zinc chloride solution ,and 7 adding thereto 3% (of the weight of the original zinc chloride reaction resulting usually produces heavy fumes and when the evolution of these has ceased. this mixture is added to the remaining 90% of the original zinc chloride bath ing until evolution of hydrochloric acid gas substantially ceases, the resultant bath. of course, containing 100 parts by weight of the zinc chloride solution and three parts by weight of the phosphorusoxychloride. 'A larger proportion ride increases translucency and homogeneity of final product. I have used as high as 10%, with varyingdegrees of homogeneity of product particularlyin regard to plastic qualities, but generally prefer to use the 3% a above indicated.

The cotton fibre paper, preferably .009 of an inch thick; is cut into sheets, preferably dried and heated somewhat above room temperature, and these sheets are then run successively through the bath of the above described solution and wound on a hollow mandrel preferably of brass, previously" heated 45 on a steam table to about 1.20 degrees Fahrenheit-,the purpose of the heating being to cause the paper to adhere promptly to themandrel. The mandrel may be about 2% inchesin outer diameter or of any size desired for the tubes to be wound thereon; A better product is obtained it the sheets can be wound on the mandrel cold. but the delay in manufacture resulting from this proce-v (lure is at present so great as to render it uncommercial. For the purpose of making solution) 'in phosphorus oxychloride. The

f and thoroughly mixed therewith as by boilof phosphorus oxychlo- Application filed March 8, 1924. Serial No. b97355.

certain optical goods the tubes formed by winding .on the mandrel consist of eight coils or laminations (resultant thickness of wall about .063 inches). Varyingv portions of the solution absorbed by the paper from the bath may be expressed, by adjusting the. pressure of a squeegee roller bearing on the tube being formed on said mandrel, according to the character of the finished product desired, and the degree of final impregnation by the solution thereby varied.

The mandrels and tubes wound on them are then hung 'in'the factory room over a No. 1 tank into which the drippings from the tubes collect. The product of each day is allowed to hang thus over night. Little change results in the thickness of wall of the tube during this curing operation,- but, during the first part of this curing or drying, say the first part of an hour, the material 75 softens perceptibly so as to be easily and deeply scored by the pressure of the finger nail and then, during the latter part of the curing or drying and perhaps during the latter part of the first hour. it ha rdens so 30 that at the end of the hour it is much harder than was the original paper.

The following morning the mandrel s, and tubes still on them. are submergedfor abouttwo hours in said No. 1 tank, in which the solution has been collected from the drip and washings of previous operations. This solution becomes progressively stronger, and

,cally cease and the tubes can then be stripped from the mandrels. The tubes so removed from the mandrels are next placed in jute bags and the bags and contents immersed in No. 2 tank which contains a like solution of zinc chloride and oxychloride, the limit of concentration being 20 Baum. They 1 are left in this No. 2 tank two days and the bag then withdrawn and suspended over No.

2 tank to allow drip from it and its contents into the tank for about/one hour.

The bag and contents are next submerged in a No. 3 tank in hich originally fresh water was placed- .ihis water is changed about once a week, it is gradually contaminated by accumulated drippings from the tubes, and the weak solution then taken out of No. 3 tank is placed in No. 2. Submersion in tank No. 8 continues for about two days.

The bag and contents are next transferred to a No. 4 tank, which is supplied with ordinary running water, for about two days.

The purpose of the above washings is to remove from the tubes the solution with which the paper was impregnated before wrapping on the mandrels and the comple tion of such removal may be tested from time to time by immersion of sample tubes in a very weak ammonia solution. If the solution becomes cloudy it means that the washing has not been sutlicient for the best high grade uses and must be. prolonged or otherwise modified to secure the desired result.

After removal from No. 4 tank the bag and contents are allowed to stand until the tubes are dry enough to be handled conveniently. Staves are then put in each tube to prevent it warping during the completion of the final drying, and tubes so mounted are put in the factory loft and allowed to remain there for about 2 days to complete the curing and drying.

The various draining and drying steps above described may be performed in special rooms, the temperatures of which can be artificially controlled, and in such case I have found an atmospheric temperature of 90 degrees Fahrenheit to give the best results. \Vhile I have obtained the best results and are left there from the particular above described process of winding the tubes and subsequent treatment of them, other standard methods of procedure employed in making so called in durated or vulcanized fibre could be substituted for the special procedure I have here described in detail.

After removal from the mandrcls the tubes shrink in diameter during the successive stages of the washing and drying process according to the degree of original saturation, which is controlled by the makeup of the solution, the time of original soaking and the pressure of the squeegee. It a light pressure was used, such as is merely sutlicient to prevent the formation of blisters between laminations, the highest degree of saturation secured in the bath persists and,

apparently as the result of the action of the solution on the cellulose, a shrinkage of about 33% in tube diameter obtains by the time the. curing process is completed. If a high squeegee pressure is used and a large part'of the solution thus expressed from the tube as it is formed on the mandrel, only a low percentage of saturation results and the tube may not shrink more than 5% to 6% in diameter during the entire process. The average reduction of wall thickness generally is something over 33%, the standard thickness of wall of such a finished tube beiue .039 inches. whereas the original thickness, as above given, was .06?) inches. This shrinkage is highly important as improving the ultimate structure of the product.

The eil'ect of increasing: the proportion of oxychloride above that given in the preferred formula herein stated is to increase the translucence of the finished product, and also its plasticity under die pressure, its flexibility under distortion and its tensile strength.

The eii'ect of the higher degrees of saturation resulting from immersing the paper in a solution of any given formula in the original bath is similar to that of the increase of the oxychloride above stated.

The material flows or stretches under pressure in the die even when it is practically cold. The tube sections it'placed in heated, slightly flaring die recesses, do not touch the walls of the die originally and, when expanded by pressure of an unheated rubber former until they come in contact with the heated die Walls, set in this expanded condition, doubtless as the result of the effect of the heat derived from the die. The greater the amount of heat applied, however, the more readily the material flows under pressure.

The main advantage of washing the tubes in progressively weakening solutions of the zinc chloride and phosphorus oxychloride is not wholly clear to me, as yet. I believe the successive washings in gradually weaker so lutions of the treating chen'iical helps to prevent excessive hydrolyzation and adsorption of treating chemical (or ions thereof) in the cellulose material in such manner as otherwise might excessively mincralize the final product. Certainly it enables me to recover all that is possible of these solu-' tions so that a given body of the liquid, after bemg stepped up in strength by its progress from tank No. 3 to tank No. 1.

may be further concentrated and added to i the impregnating bath throughwhich the paper 18 passed before winding on the man drel, or the chloride and oxychloride con-- tents thereof otherwise recovered. Similar considerations of economy dictate the dcscribed method of recovering the drippings from the tube. All these drippings and washings might be thrown away and fresh water used in each washing tank if the consequent waste were commercially permissible. v

The product resulting from the above described process, or from any gcnerall y similar one involving only immaterial modificathe process of manufacture, as does the in-' durated or vulcanized fibre hitherto known. It is somewhat hydroscopic. It will take and hold any ordinary dye, paint or lacquer.

It has a tensile strength and an elastic limit which compare favorably with those of the best. vulcanized fibre product now on the market.

It has in high degree the property of flowing under pressure, as in a die. For e1;- ample, tubes formed of it may, without injury, be quickly spun or pressed in a die down to about one half their original diameter, whereas tubes formed of the best other form of indurated fibre known to me cannot be reduced in diameter to anything like that extent except by very careful manipulation in a heated die performed so slowly that the heat of the die scorches the product and there is an incipient crushing of the fibre. Similarly, tubes of my material can be easily expanded 22 percent in diameter, while tubes of the best other indurated fibre knownto me cannot be expanded beyond 13 percent of their original diameter. The best results under compression are obtained with the product dry, while the best results under expansion are obtained when the product is. moist. Also strips of my material .300 inch thick can safely'be rolled down to .187 inches in thickness without injury. whereas similar strips of indurated fibre heretofore on the market cannot be so rolled down over .075 inch, without breaking up. In the case of sheets the improvement in this regard is still more marked when my improved n'iaterial is used, as compared with best varieties of other iudurated fibre products known to me. Another novel characteristic of my material 1sthe substantial freedom of sheets from blistering in all stages of manufacture, such blistering being a source'of great waste and loss in the manufacture of sheets out of other forms of indurated'fibre, even when the best grades of paper are used, and becoming practically prohibitive. when an attempt is made to use The material sets in whatever form it'is thus i'nolded, it does not become brittle under the continued application of heat, as is the case with the ma ority of other cellulose products made from fibre and it does not warp to any appreciable extent has practically no porosity, but I after such setting,

microscope they disclose a much less striated structure than do specimens of the best other form of indurated fibre known to me.

Microphotographs of cross sections of the mass also show scattered deposits of a white powder, the nature and origin of which have not yet been determined.

It may be made pliable to the highest degree .when slightly humid if complete saturation was employed in the initial treatment, and to lesser, degrees when such saturation-was less complete. Pieces .045 inch in thickness have been bent sharply cold and when longitudinal sections of the mass are examined under the through 180 degrees back and forth without showing racture at the pointof bending. It is qulte resilient when cold and practically resumes its original shape after moderate bending, but if bent hot it takes a permanent set.

It may be given high non-conducting and dielectric properties when pure, and these may be further heightened by mixing other suitable non-conducting materials with the original fibre.

Its texture is such that it can be easily and accurately machined with very little wear on the cutting edges of the tools used and its surfacesare capable of receiving a high polish, as by butting or other usual polishing process.

\Vhen its surfaces have been treated with the copper salts solution described in my application, Serial No. 697,956 filed of even date herewith, pieces can be quickly welded together under pressure so asto form one practically homogeneous body of great mechanical strength and toughness so that thin-walled articles of fairly diversified contour, such as goggle frames, made by joining pieces of it, can be thrown violently on a stone floor, or against a sharply serrated'steel surface, without developing fracture or substantial disintegration.

It is understood, of course, that the preferred process herein described is subjected to variations to obtain various etfects, by modifying the proportions of the constituents, the order or character of certain of the described steps, degrees of heat or moisture employed, etc. without departing from the essential novelty of, my discovery or invention, and that chemical or other equivalents may be substituted for some or all of the ingredients mentioned with like product obtained which, while possibly interior to the best form of my invention in some features. would still involve some or all of the novel principles herein disclosed.

The herein described product has a tensile strength of from 12,000 to'15,000 pounds per square inch of cross section accord to the care exercised, and the perfection at taincd, in its manufacture, and does not be gin to develop any permanent elongation until subjected to about 75 per cent of the breaking strain. Uncalendered sheets develop an elongation of about 5 percent before rupture. \Vhen calcndered, the clongation reaches 10 percent.

Having described my invention, I claim:

1. The herein described process of producing indurated fibre which comprises impregnating a body of cellulose with a solution to which has been added a phosphorus oxychloridc, washing out said solution and drying the product.

2. A process such as set out in claim 1 in which the degree of said impregnation is carried to the point of practical saturation with the solution.

3. A process such as set out in claim 1 in which said washing is done in successive steps.

4. A process such as set out in claim 1 in which said washing is done in successive steps and the baths for said washing steps, except the last, consist of progressively weaker solutions similar to the original impregnating liquid.

5. The herein described process of producing indurated fibre by treating felted cotton fibre, which comprises impregnating sheets thereof with a solution to which has been added a phosphorus oxychloride while being assembled in a laminated structure, washing out said solution and drying the product. ,6. A process such as set out in claim 5 in which the degree of impregnation is carried to the point of practical saturation with the solution.

7. A process such as set out in claim 5 in which said washing is done in successive steps. l

8. A process such as set out in claim 5 in which said washing is done in successive steps. and the baths for said washing steps, except the last, consist of progressively weaker solutions similar to' the original impregnating liquid.

9. The process of treating cellulose which comprises iu'ipregnating the same with a so-v lution containing a major proportion of a metallic chloride in water to which has been added a minor proportion of phosphorus oxyehloride. compressing the same into a mass of indurated fibre, washing out said solution and drying the product.

10. The process of treating cellulose which comprises impregnating the same with a solution containing a major proportion of zinc chloride in'water to which has been added a minor proportion of phosphorus oxychloride. compressing the same into a mass of indurat'ed fibre, washing out said solution and drying the product.

11. A process such as set out in claim 9 in which the degree of saturation'is' carried to the point of practical saturation with the solution.

12. A process such as set out in claim 9 in which said impregnating liquid contains about 100 parts by weight of a solution of said metallic chloride and water. of a density of 72 degrees Baum at degrees Fahrenheit. to which has been added about :3 parts by weight of said phosphorus oxychloride.

13. A process such as set out in claim 9 in which said washing is done in successive steps.

1 1. A process such as set out in claim 9 in which said washing is done in successive steps and the baths for said washing step, except the last. consist of progressively weaker solution similar to the original impregnating liquid.

15. The herein described process of treating felted cotton fibre which comprises impregnating sheets thereof with a solution containing a major portion of zinc chloride in water to which has been added 'a minor proportion of phosphorus oxychloride while being assembled in a laminated structure, washing out said solution and drying the product.

16. The herein described process of treating felted cotton fibre which comprises impregnating sheets thereof with a solution containing a major portion of zinc chloride in water to which has been added a minor proportion of phosphorus oxychloride while being assembled in a laminated structure, washing out said solution and drying the product after compression and conversion have produced a substantially non-laminated mass of indurated fibre.

17. A process such as set out in claim 15 in which the degree of impregnation is carried to the point of practical saturation with the solution.

18. A process such as set out in claim 15 in which said washing is done. in successive steps.

19. A. process such as set out iirclaim 15 in which said washing is done in successive steps and the baths for said washing steps. except the last. consist of progressively weaker solutions similar to the or ginal impregnating liquid.

20. Av particular form of the hereindescribed process in which the impregnated sheets of felted tightly intoa tube on a mandrel, dried therecellulose fibre are woundon and then dipped in a mixture of zinc chloride, and water to which has beenadded an oxychloride of a density not exceeding degrees Baum at room temperature,-to fa- (ci-ilitate stripping said tube from said manrel. i

21. A product of the herein claimed process, being a solid substantially homogeneous body of approximately pure indurated cellulose fibre having at least a tensile strength of about 12,000 pounds per square inch of cross section.

22. A product of the herein claimed process, being a solid substantially homogeneous body of approximately pure indurated cellulose fibre having a tensile strength in excess of 12,000 pounds per square inch of cross section and having a specific gravity of about 1.25.

23. A product of the herein claimed process, being a solid substantially homogeneous body of approximately pure cellulose which is plastic when subjected to ordinary die pressures at room temperature.

24. A product of the herein claimed process, being a solid, substantially homogeneous body of approximately pure cellulose fibre which is highly elastic at room temperature but takes a ermanent set when distorted at suitabl hig er temperatures.

25. ess, being a solid body of approximately pure indurated cellulose fibre which is highly translucent throughout.

26. A-product of the herein claimed'proc ess, being a solid substantially non-porous body of approximately purecellulose having flexibility at room temperature when slightly humid, such that a thin section thereof may he flexed sharply back and forth about fifty times without developing fracture at the point of flexure.

27. A product ess, being' a solid body of approximately pure cellulose fibre pliable at medium temperatures and maintaining such pliability after prolonged heating.

product of the herein claimed procof the herein claimed procs 28. A product of the herein claimed process, being a solid consisting of substantially homogenized cellulose fibre, together with residual amounts (about .10 per cent) of modifying materials of cementitious matter,

. such as zinc and phosphorus compounds,

which solid is semi-plastic under mechanical stress, somewhat translucent, substantially uninjured by severe flexure, capable of assuming a plastic set under the action of heat, having an elastic limit ofabout 9,000 pounds under tension and a tensile strength of about 12,000 pounds with about 5 per cent elongation before fracture, capable of great distortion under lateral pressure and capable of being swaged into modified shapes without separating the initial laminae of construction and having a specific gravity in excess .ened baths of the same solution.

' 30. A process such as defined in claim 29 in which said bath is formed by initially mixing saidoxychloride with about 10 per cent of the original zinc chloride solution,

and then adding said mixture to the remaining 90 per cent ofsaid zinc chloride.

. 31. A' process such as defined in claim 29 in which the cellulose fibre originally saturated is in the form of sheets of paper, and

in which such saturated sheets are compact ed together by winding on a mandrel under pressure from an adjacent roller.

32. Aprocess such as defined in claim 29 in which the mixing of the bath constituents is effected by boiling until the evolution of hydrochloric acid gas substantially ceases.

HORACE H. CLARK.