US2086418A - Treatment of cellulosic bodies - Google Patents

Description

'Patented July 6, 1931 Wilmington, Del,

asslguors to E. I. du Pont de Nemours 6; Company, Wilmington, Del., a. corporation of Delaware No Drawing. Application September 4, 1934, Serial No. 2,692

deterloretlon of organlc materials and more partlculorlv to the stabilizing of cellulose, cellulose manufactures and chemical derivatives of cellulose.

It hes been discovered. that deterioration of the above materials cambelefiectively retarded by treating them with smell-'emouuts of certain, stshlllmng chemical agents, namely, polycyclic phenols having at least two non-cohdensed carbocycllc nuclei. memplesof *suofiphenols are p-hydroxy-dipheuyl and p jcycloheml phenol.

The deterlorstlon oi celliiloslc substances such as those with which the"preseut invention is concerned seems to be induced or accelerated by light, particularly ultraviolet light. In other words, the deterioration seems in many lnstcnces to he photochemical since its rapidity frequently varies dlrectly with the intensity of the light.

In the absence of light this deterioration is often very slow and imperceptible except over long periods ct time but takes place, nevertheless, as evidenced by the dlscoloretion and weak: suing of paper, hooks, cotton fabrics, newspaper files, etc, even when stored. in dork places at comparatively low temperatures. Thus, while the rate of deterioration may very vvlth the pertlcular conditions, the present agents will be lcuud efiective for retarding lt under any given set of conditions. However, neither the nature of the deterioration of celluloslc substances (whether hydrolytlc, ofidetlve or otherwise) nor the manner in which the present agents functies to prevent it is definitely known, and it is not desired to be confined to any theory, thereof.

The general object of this invention is therefore to provide methods for retarding the deleterious efiects of aging on paper, cellulosic fabrlcs, sud various other celluloslc materials. A pertlculer object of this lnventlon is to provide methods of decreasing the deterioration, due to or lmtlated by ultrevlclet'rays and other causes, of these celluloslc substances included in the group consisting of regenerated cellulose, cellulose others and organic sold esters of cellulose. The materials may he in the form of fibers, storms-lawns, and thin sheets of different sizes, shapes and transparency. Examples of cellulose esters with which the present agents may be used effectively are cellulose acetate, cellulose butyrste, cellulose "laurate, cellulose isobutyrate,

cellulose propionate, etc. Examples of cellulose ethers are methyl cellulose, ethyl cellulose, benzyl cellulose, dodecyl cellulose, propyl cellulose, clnnamyl cellulose. glycol cellulose, and

(or. or-so) cellulose glycolllc acid. The cellulose esters and others may be of the high or low substituted types, having for example from one substltuent group for eight glucose units up to three substltuent groups for each. glucose unit.

Another object of this invention is to provide methods of retarding the deteriorating effect of aging on, various cellulose manufactures included in a, group comprising paper, cotton filaments and woven and. knitted fabrics such as cotton, 10 linen, remle, jute, etc. These objects are accompllshed by treating paper, cotton goods and the other aforementioned cellulodc materials with a. polycyclic phenol having at least two non-condensed carbocycllc, nuclei, which compounds 5 have the property of stabilizing the celluloslc materials against the injurious efiect of aging or exposure to concentrated ultraviolet rays.

Other objects of this invention and methods forthelr attainment will be apparent as the description proceeds.-

These objects are accomplished by treating paper, cotton goods, and other aforementioned celluloslc materials with a. polycyclic phenol havlug at least two non-condensed cerbocycllc nuclei', as illustrated in examples which follow.

Specific examples of some of the suitable stabilizing egeuts that fell within the scope of this invention are the following phenols which, as will be seen, are of two types, those having non-condensed aromatic nuclei and those havlog on allcyclic ring.

Non-condensed polycyclic phenols with only aromatic nuclei o-Hydroxydiphenyl m-Hydroxydiphenyl p-liydroxydipheny o,o'-Dlhydroxyd1phenyl 40 mm'-Dlhydroxydrphenyl 'Dl (l-hydroxyphenyl) -phenylmethane Di(4-hydroxypheny1) dlm'ethylmethsne 131(4-hydroxynephthyl) dlmethylmethane BN3 methyl 4 hydromheuyl) dlmethylmethone Di(4-hydroxyphenyl) methylethylmethane Biol hydroxy 3,5 dlmethylphenyl) dlmetlrvlmethane D101 hydroxy 3,5 dlmethylphenybdipropylmethane The last six phenols of the above table are of particular interest in this invention because in the pure state they have very little if any characteristic odor or tendency to discolor. These phenols maybe described generally as polycyclic phenols having at least two non-condensed carbocyclic nuclei and having the para position to their phenolic hydroxyl groups occupied by tertiary aliphatic carbon atoms.

Non-condensed polycyclic phenols having an alz'cyolic ring Example 1 This example illustrates the stabilization of cellulose acetate rayon. Strips of the woven fabric wide were immersed for one hour in a alcoholic solution of p-hydroxydiphenyl. The excess liquid was squeezed out and the treated strips kept side by side with untreated control strips of exactly the same size and shape for twenty-four hours at 25 C. and 50% relative humidity. Two of the controls and two of the treated strips were then tested for elongation and breaking strength on a Scott testing machine. The values obtained-approximately the same for bothwere taken as 100%. All of the remaining strips, together with the remaining controls, were then exposed to ultra-violet rays under a Cooper-Hewitt quartz mercury vapor lamp in order to accelerate the deterioration of the fabric. All strips were placed at a distance of approximately 24 inches from the lamp where the temperature was approximately 30 C. Exposure was continued for 57 hours. Two control strips and two treated strips were removed at the end of 25 hours and 57 hours, then stored at 25 C.

and 50% relative humidity for 24 hours, and iinally tested for elongation and breaking strength in the same manner as before exposure. At the end of 25 hours the untreated control retained 7.5% and the treated fabric 60.3% of the original strength. At the end of 57 hours these values were 1.5% and 44.1%, respectively. By this time the untreated control was very weak, readily torn, and whollyuseless, but the treated fabric, while definitely weakened, was still usable.

p,p'-Dihydroxydiphenyl, the monomethyl ether of p,p'-dihydroxydiphenyl, di(4-hydroxyphenyl) sulfone, di(4-hydroxyphenyl) ether, di(4-hydroxyphenyl) dimethylmetliane, naphthyl) dimethylmethane, di (4-hydroxyphe nyDphenyl methane, etc., may be used in the above example instead of p-hydroxydiphenyl and good results obtained in retarding the weakening, discoloration and general disintegration of the fabric. These agents are also effective with regenerated cellulose, cotton, and paper. While they may be used in the raw material, they are more conveniently and effectively applied to some di,(4-hydroxymanufacture thereof as viscose rayon (fibers or fabrics), thin transparent sheets of regenerated cellulose such as those ordinarily used for wrapping purposes, and cotton or rayon textiles, rope. threads, etc.

As previously pointed out these agents are also effective when the treated base material is subjected to various temperatures and/or to light of various types and intensities and/or when aged in the absence of light, the ultraviolet light merely being used for quick results.

Example 2 Woven viscose rayon fabric was treated with a 5% alcoholic solution of p-hydroxydiphenyl in the same manner as in Example 1. After 36 hours exposure to ultraviolet light under the same conditions as in Example 1, the treated fabric ri. tained 72.7% of its original strength while the untreated control retained only 51.6%. The corresponding figures at the end of 72 hours were 61.8% and 28.3%.

In the above example the p-hydroxydiphenyl may be replaced by di(4-hydroxyphenyl) ether, m-hydroxydiphenyl, di (4-hydroxyphenyl) dimethylmethane, di(4-hydroxyphenyl) methyl phenylmethane, di (4-hydroxy-3-methylphenyl) dimethylmethane, etc., and good results obtained. That latter three agents are particularly desirable because the treated and aged fabric is quite free from the odor of phenol and also retains its original luster and hue. Phenols not having the characteristic p-tertiary carbon atoms frequently tend to discolor under even normal conditions of exposure and more so in the presence of concentrated ultraviolet light. In substituting these agents for the p-hydroxydiphenyl appropriate low boiling solvents which do not attack the base material should be used in applying these agents. Paper, paper pulp, cotton and cellulose derivatives may also be rendered more resistant to deterioration by treatment with these alternative agents after the general manner of Example 2.

Earample 3 Woven viscose rayon fabric was soaked in a 5% alcoholic solution of o-hydroxydiphenyl and the treated fabric exposed to ultraviolet light together with untreated controls. After 72 hours the treated fabric possessed 36.7% of its original strength and the control only 28.3%.

Example 4 Woven viscose rayon fabric was impregnated with a solution of p,D'-dihydroxydiphenyl in a mixture of alcohol and toluene of such concentration (5-7%) to give about 4% by weight of the stabilizing agent upon the fabric. The solvent was then allowed to evaporate and the dry treated fabric exposed to ultraviolet light together with untreated controls. After 36 hours the former possessed 57.7% of its original strength and the control only 51.6%. At the end of 72 hours, these figures were 42.3 and 28.3, respectively.

Example 5 ren better results obtained. the treated fabric aving after 36 hours, 86.9% of the original rength; Of all the agents tested, the oand -cycloheml phenols gave the best results. This ill be evident from a comparison with the exmples given above.

Example 6 Strips of paper were immersed for one hour in I 10% alcoholic solution of p-hydroxydiphenyl. he wet strips of paper were then removed from 1e impregnating bath and allowed to dry toether with untreated controls for 24 hours at 5 C. and 50% relative humidity; The treated nd untreated paper strips were then exposed to ltraviolet light in the manner of wample 1 ar 6 days. At *the end of this time, both were ested mtensile strength. The control strip roke upon application of 2.6 pounds while the seated paper-required a tension of 5.0 pounds eiore breaking. Both strips of paper were cut mm the same sheet of paper and were V ride.

It has been found that an impregnation with bout 4% of the stabilizing agentis satisfactory a most instances. The amount required for best esultslwill, however, vary somewhat depending n the particular stabilizer used and the maerial treated. As a rule, the quantity of the tabilizer should lie within the range 0.25% to .0% based on the weight of material treated. Quantities outside this range are, however, still iseful and are by no means precluded.

It will be seen irom the preceding examplehat impregnated samples show marked improvement over the untreated samples in their rerlstance to deterioration as induced or caused my ultraviolet light. It is again desired to point rut, however, that the ultravioletlight is only a nethod for obtaining rapid results. The rate of ieterioration is also decreasedmarkedly under ither conditions as, for-example, in the absence 3f light and in ordinary sunlight. In other words, the present agents are 'efiective in retar-ding the deterioration of cellulosic substances when subjected to light of diflerent types and intensities.

It will be noted that all the systems in which the presentagents are used are closely related. Regenerated cellulose, cellulose ethers or esters, and manufactures of both, all have a greater or less number of unsubstituted or partially substituted (i. e., etherifled or esteriiied) glucose units ioined together in a complexjashion. It seems reasonable to suppme that the tendency of cellulosic materials to deterioration on aging may be due to disruption of the bonds between glucose units and/or the rearrangement of these units or building stones to a more degraded structure. Thus the systems in which these agents are used not only have a common and distinctive chemical relation irrespective of the processes or the invention, but all these systems are probably aiiected similarly by all of the agents of this invention.

As many apparently widely different embodi ments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that there are nospecifio limiting embodiments except as defined in the ap pended claims. J

We claim:

1. Paper impregnated with 0.25% to 5.0% o! a polycyclic phenol having at least two non-condensed carbocyclic nuclei. 7

2. The process of rendering paper more resistant to the deleterious eflect of aging which 0021- sists in impregnating its fibrous mass with 0.25% to 5.0% of a polycyclic phenol having at least two non-condensed carbocyclic nuclei.

3. The process of rendering cotton and fabricated cotton more resistant to the deleterious eiiect of aging which consists in depositing on the fibrous surfaces 0.25% to 5.0% of a polycyclic phenol having at least two non-condensed car'- bocyclic nuclei. 7 4. The process of. rendering regenerated cellulose fibres and fibrous manufactures thereof more resistant to the deleterious eflects of using which consists in depositing on the fibrous surfaces 0.25% to 5.0% oi a polycyclic phenol having at least two non-condensed carbocyclic nuclei.

5. Fibres and fibrous manufactures'thereof of the group consisting of cellulose and regenerated cellulose having deposited on the fibrous surfaces 0.25% to 5.0% oi a polycyclic phenol having at least two non-condensed carbocyclic nuclei.

6. Cotton and fabricated cotton having deposited on the fibrous surfaces 0.25% to 5.0% of a polycyclic phenol having at least two non-condensed carbocyclic nuclei. 7. Fibres of regenerated cellulose and manuiactures thereof having deposited on the fibrous suriaces,0.25% to 5.0% of a polycyclic phenol having at least two non-condensed carbocyclic nuclei.

JAMES KARE HUNT. GEORGE HENRY LATHAM.