US2091972A - Treatment of materials having a basis of esters - Google Patents

Description

Patented Sept. 7, 1931 UNITED STAT/ESJ PATENT OFFICE TREATMENT OF MATERIALS HAVING A BASIS OF ESTERS aware No Drawing. Application May 22, 1936, Serial No. 81,268

15 Claims.

This invention relates to the saponification of organic esters of cellulose, particularlydin the form of filaments, threads, ribbons, fabrics, 'films and like materials and is a continuation in part 5 of. U. S. application S. No. 11,080 filed 14th March,

of a substance whichwliminishes the swelling V action. The presence of substances adapted to diminish the swelling of the ester is of particular advantage with a view to obtaining products go of high tenacity and avoiding fusion or coalescence of the filaments of multi-filament yarn which mightotherwise occur when using relatively high'concentrations of the base.

' According, therefore, to the present invention, 25 in the saponification of organic esters of cellulose, and particularly of filaments, threads, yarns, fabrics and like materials'having a basis of such esters, the saponification is effected by means of a nitrogenous organic base, having 30 a swelling action on the cellulose ester, in the presence of a substance which is not a saponifying agent for the cellulose ester and which diminishes the swelling of organic esters of cellulose. Among the most useful of agents adapted to di-' 35 minish the swelling of organic esters of cellulose are water soluble salts of organic acids, and.- polybasic inorganic acids, for example the sodium, potassium and ammonium salts of phosphoric acid, boric acid, acetic acid, tartaric acid, citric 40 acid, lactic acid, sulphuric acid, thiosulphuric acid and sulphurous acid.

Other suitable swelling repressing agents include the barium; strontium, calcium, magnesium and zinc salts of the organic acids referred to v4:15 above, the sodium, potassium and ammonium oxalates, sodium and ammonium chloride, sodium, potassium and ammonium formate and the sugars, for example, cane sugar, glucose,

fructose, mannitol and sorbitol.

5 The sodium and potassium salts of strong inorganic acids, such for example as hydrobromic, hydriodic, nitric, perchloric and thiocyanlc acid, have a tendency to swell the cellulose derivative. This tendency is even more evident in the correspending strontium, calcium and barium salts.

esters of cellulose.

Such salts are not therefore in general suitable as swelling repressing agents. Sodium chloride can however be used and the ammonium salts of all these acids except thiocyanic can also be used. A simple experiment will of course indi- 5 cate the suitability or unsuitability of any particular substance.

Among the nitrogenous organic bases which may be used mention may be made of methylamine, ethylamine, propylamine butylamine, isopropylamine, isobutylamine, di-isobutylamine, amylamine, di-isoamlvlamine, the ethanolamines, particularly .mono -ethanolamine, diamines of relatively low molecular weight, for example ethylene diamine, propylene diamine and trimethylene diamine, heterocyclic bases, for example pyridine and piperazine and poly-methylene amines, for example cyclohexylamine. In general, water-soluble organic nitrogenous bases in which each carbon atom; directly attached to the nitrogen atom is directly attached to three other carbon atoms are suitable. The base may for example be an aliphatic amine containing up to six carbon atoms or may bea diamine in which the two nitrogen atoms are separated by 5 up to four carbon atoms. Bases which contain aromatic groups attached to the nitrogen through aliphatic groups are also suitable. For example, excellent results have been obtained with the benzylamines, particularly monobenzylamine. Such bases in common with the benzylamines are entirely new as sapunifying agents for organic These two classes of base are of great utility even in the absence of swelling repressing agents.

The process of the invention enables saponification to be effected, even'with high concentrations of organic base e. g. between 20 and 40% V and at high temperatures for instance 60 to 90 0., not only without damage to the materials 4.0

but so as to improve their serimetric properties. Thus, materials saponified by the process of the invention may have high tenacity, extensibility and elasticity. The use of high concentrations of organic bases at high temperatures enables saponification to be conducted more rapidly than would otherwise be possible. The invention is not however limited to the use of high concentrations of base or high temperatures. The presence of substances which diminish the swelling action of the bath isof advantage even at low or ordinary temperatures and with low concentrations of organic base.- 7 The concentration and temperature of the saponifying medium will depend on the nature 01 the materials treated and the rate at which saponification is to be effected. With methylamine for instance the concentration may range from below 5% to over 30% and the temperad ture from below l5 C. to above 90 0. Baths containing 15-20, 25 or 30% methylam'ine have been found useful at temperatures'between 20 and 30 C. as well as at higher temperatures e.'g. 40-50 or 60-70 or 80 C. Other bases of somewhat similar strength for instance ethylamine and benzylamine may be used at the same temperatures and concentrations. In general the stronger the base the lower the concentration and/or temperature required for a'given speed of saponification. With ethylene diamine for example though concentrations below 5% and temperatures below 15 C. can be used saponification underthese conditions is very slow and higher concentrations and temperatures e. g.

20 or to or and -50 up to 95 C. or more are more generally useful.

1 The amount of swelling repressing agent used will depend on the strength and concentration of the base, the temperature. of the bath and the 25 nature of the ,materials treated and of the final products required. For example, in the saponification of cellulose acetate yarns, by means ofbaths containing 10-20% of methylamine or ethylamine at 25-65 C., concentrations of sodium 30 acetate of 2-2o% and particularly 5-15%- have been found to enable a. considerably higher tenacity to-be obtained in the products than would otherwise result. considerably higher concentrations have also been used e. g. 20-35% or even 5 more. On the other hand a marked increase in tenacity has resulted from the presence even of 1% of sodium acetate. The more sensitive the materials and the higher the strength and concentration of base and temperature, the higher 40 the concentration of swelling repressing agent required to give the maximum tenacity; I

The saponific'ation may .be effected by any suitable means. materials may be treated in hank form in a vessel containing the saponifying medium and the sodium acetate or other salt which diminishes the swelling effect of the base, and allowed to remain therein until the'desired saponification is effected. Again, the materials may be drawn continuously through the saponifying bath at such a rate that the desired saponification is effected by the time the materials leave the bath. It is of advantage when adopting this method to treat a number of threads in warp formation, that is in parallel alignment in the same plane.

facilitates uniform saponification as between thread and-thread.

' The saponification, whether conducted as .a continuous operation or as a bath process,- may be conducted under pressure, as described in U. S.

application S. No. 11,080 filed 14th March 1935. By this means higher concentrations of volatile bases and/or higher temperatures may be employed than would otherwise be practicable. When in' a continuous process saponiflcation is effected under pressure a convenient method is to pass the threads through a vessel partly filled with the saponifying medium, the threads entering and leaving the vessel through small holes above the 7 level of the liquid. To facilitate threading up, the holes are preferably formed 'in members readily'det'achable from the apparatus. Thus in one form of apparatus there is at each end of the saponifying vessel an aperture over which, 7 when the apparatus is in operation, is clamped a Thus, for example, yarn and like This method detachable perforated plate, the perforations being sufliciently large to take the threads without permitting an excessive loss of pressure. Guides or rollers may be provided in the vessel so that the greater part of the path of the materials 5 lies below the level to which the saponifying liquid will rise. When working with this type of apparatus in its simplest form, the materials are threaded through the perforations in the one plate, passed under the guides, or rollers, which 10 are conveniently situated near the bottom of the vessel, and through the perforations in the other plate. The plates are then clamped in position and the saponifyingliquid is run into the vessel up to the required level. Heating coils or other 16 suitable attemperating means are provided for use when the process is to be carried out at a temperature differing from atmospheric temperature. If the process is to becarried out at a temperature sufilciently high, it may be unneces- 2'0 sary to apply external pressure to-the liquid, its own vapour pressure at that temperature being sufficient. Ingeneral, however, witha view to maintaining the composition of the saponifying medium constant, the required pressure may be 25 obtained by supplying air or other suitable gas under pressure to the space above the liquid.

saponification may be effected under little or no applied tension, so as to facilitate contraction of the materials during saponification. With this 30 in view it is of advantage to provide intermediate rollers which are preferably positively driven at speeds which progressively decrease along the path of the materials. On the other hand, if the saponifying mediumis such as to exert the neces- '3 sary softening efiect upon the materials, they may even be stretched during sapomfication. Whether the saponification is. to be carried out so that the materials contract, or so "that they are stretched, or so that no lengthening. or contraction takes 40 place, it is of advantage to provide a series of positively driven rollers along the path of the materials, since it is found that such an arrangement leads 'to great uniformity in the properties of the saponified materials along their 45 length, and particularly uniformity in their tenacity, extension and dyeing properties.

Threading-up of the materials before admis- 1 sionof the saponifying liquid to the vessel may be avoided by adopting a slightly more elaborate ap- 50 paratus in which the guides or rollers are attached to a frame so that they can be lifted above the surface of the liquid for threading up and depressed and fixed in position below the surface of the liquid when this has been accomplished. 55

As indicated above, saponification'may be carried out as a batch process. Thus yarns in hank or other package form, or fabrics may be s pended within a saponifyingmedium maintained under pressure in a closed vessel. The pressure 60 may be obtained byany suitable means, for example by means of pumps or compressors or by means of compressed air. On the other hand, as in the continuous process, when a saponifying liquid at a sufliciently high temperature is em- 65 ployed, the. vapour pressure of said liquid may be sufl'icient to provide the necessary pressure, or the pressure may be obtained by introducing a com-- pressed gas into the space above the liquid. The following example illustrates the invention: p r

Example Cellulose acetate yarn is completely saponifled containing 1520% methylamine and -2-5% sodium acetate at 40-60" C. The tenacity of the yarn is considerably higher than if the sodium actate is omitted. The amount of sodium acetate may be increased up to 15 or even 20%. Instead of sodium acetate other salts of organic acidsmay be used for instance sodium lactate. Instead o methylamine ethylamine may be used.

Although the invention has been described with particular reference to the saponification of filaments, threads, ribbons, fabrics, films and like materials of cellulose actate, it is also applicable to the treatment of materials comprising otheresters of cellulose, particluarly organic esters, i. e. esters containing acidyl groups, for example simple esters such as cellulose formate, propionate or butyrate, ether-esters, such as ethyl cellulose acetate and oxy-ethyl cellulose actate, and mixed esters, such as cellulose acetate propionate, cellulose acetate-propionate-butyrate and nitrocellulose acetate. The cellulose acetate or other base of which the materials to be saponified are made may be of high, medium, or low viscosity. For example in the case of celluloseacetate the viscosity may be ,above to 50 or even 100 or more, measured by comparing the viscosity of a 6% solution of the cellulose acetate in acetone at 25 C. with that of glycerine at the same temperature, taken as 100; or may be considerably 30 lower, for example 10 or 15 to 20, on the same scale. With a View to obtaining materials of high tenacity, it is of *advantage that the materials treated should have been stretched to a relatively high extent at some stage in their manufacture.

3.3 They may, for example, have been stretched considerably during their formation by a wet spinning process such as those described in applications S. Nos, 402,785 filed 26th October, 1929,

418,414 filed 3rd January, 1930, 437,423 filed 20th March, 1930, 469,622 filed 21st July, 1930,

and 601,043 filed 24th March, 1932, or againstretching may have been efiected as a separate operation subsequent to their production. Further, the materials may be softened by means of v steam or hot water; and stretched, as described, for example, in application S. Nos. 4,510 and 4,511 both filed onlst February, 1935. The materials may have undergone a shrinking operation e. g. after stretching.

The degree of saponification effected will depend to some extent upon the object of the process; whether, for example, it 'is required merely to impart to the materials an aifinity for cotton dyes, or to increase their tenacity, or to I produce materials consisting substantially of regenerated cellulose. The degree of sap'onifica tion may, for example, reduce the original acid radicle content by 15-20%- or less, or may be ,more extensiveinvolving a reduction of 25 or 30 an up to 40 or 50% or from '60 to '75 or 80% or may even effect substantially complete removal of the acid radicle groups. By the process of the invention it is possible to obtain. a deep-seated saponifica- ,tion extending to a considerable depth beneath 35 the surface of the materials or even throughout substantially the whole section of the material.-

Having described our invention, what We desire to secure by Letters Patent is:-,

1. Process ,for the saponification of organic 70 esters of cellulose, wherein the saponification is efiected by means of a nitrogenous organic base having a swelling action on the cellulose ester, in

the presence of a substance which is not asaponifying agent for the cellulose ester and which 75 diminishes the swelling or the cellulose ester.

2. Process for the saponification of filaments,

' threads, yarns, fabrics and like materials having a basis of organic ester of cellulose, wherein saponification is efiected by means of an aqueous liquid containing a nitrogenous organic base having a swelling action on the cellulose ester and a substance'which is not a saponifying agent for the cellulose ester and which diminishes the swelling of the cellulose ester.

3. Process for the saponification of filaments, 10 threads, yarns, fabrics and like materials having a basis of organic ester of cellulose, wherein saponification is effected by means of an aqueousliquid containing a water-soluble nitrogenous organic base in which each carbon atom directly at 15 tached to a nitrogen atom is directly attached to three other atoms and which has a swelling action on the cellulose ester, and a substance which is not a saponifying agent for the cellulose ester and which diminishes the swelling of the cellulose 20 ester; a a

4. Process for the saponification of filaments,

threads, yarns/fabrics and like materials having a basis of organic ester of cellulose, wherein.

saponification is effected by means of an aque- 25 ous liquid containing a water-solublenitrogenous aliphatic base containing not more than six-carbon atoms which is a swelling agent for the cellulose ester, and a substance which is not a saponifying agent forthe cellulose ester and which 30 diminishes the swelling of the cellulose ester.

5. Process for the saponification of filaments, threads, yarns, fabrics and like materials having a basis of cellulose acetate, wherein saponification'is effected by means of an aqueous liquid 35 containing a nitrogenous organic base having a swelling action onthe cellulose acetate and a substance which is not a saponifying agent for the cellulose acetate and which diminishes the swelling of the cellulose acetate. 40

6. Process for the saponification of filaments, threads, yarns, fabrics and like materials having a basis of cellulose acetate, wherein saponification is effected by means of an aqueousliquid containing a water-soluble nitrogenous organic 5 base in which each carbon atom directly attached to a nitrogen atom is directly attached to three other atoms and which has a swelling action on the cellulose acetate, and a substance which is .not a saponifying' agent for the cellu- 5 lose acetate and which diminishes the swelling of the cellulose acetate.

.7. Process for the saponification of filaments,

' threads, yarns, fabrics and like materials having a basis of cellulose acetate, wherein saponifica- "55 tion is efiected by means'o'f an aqueous liquid containing a water-soluble nitrogenous aliphatic base containingnot more than six carbon atoms which is a swelling agent for the cellulose acetate, and a substance which is not a sa onifying agent for the cellulose acetate and w ich diminishes the swelling of the cellulose acetate.

8. Process for the saponifica ion of filaments..- threads, yarns, fabrics'and like aterials having -a basis of organic ester of cellulose, wherein 63 saponification is efiected by means of an aqueous liquid containing a. nitrogenous organic base having a swelling action on the cellulose 'ester and a water-soluble salt of an inorganic polybasic acid, said salt being one which is not a saponifying agent for the cellulose ester and which diminishes the swelling of the cellulose ester.

9. Process for the saponification of filaments, threads, yarns, fabrics and like materials having a basis of organic ester of cellulose, wherein saponification is effected by means of an aqueous liquid containing a nitrogenous organic base having a swelling action on the cellulose ester and a water-soluble salt of an organic acid, said salt being one which is not a saponifying agent for the cellulose ester and which diminishes the swelling of the cellulose ester.

10. Process for the saponification of filaments, threads, yarns, fabrics and like materials having a, basis of organic ester of cellulose, wherein saponification is effected by means of an aqueous liquid containing a nitrogenous organic base having a swelling action on the cellulose ester and a sugar, which sugar diminishes the swelling of the cellulose ester.

11. Process for the saponification of filaments,

. threads, yarns, fabrics and like materials having a basis of cellulose acetate, wherein saponification is eflected by means, of 'an aqueous liquid containing a nitrogenous organic base having a swelling action on the cellulose acetate and a water-soluble salt of an inorganic polybasic acid, said salt being onewhich is not a saponifying agent for the cellulose acetate and which diminishes the swelling of the cellulose acetate.

12. Process for the saponification of filaments, threads, yarns, .fabrics and like materials having a basis of cellulose acetate, 'wherein saponification is efi'ected by means of an aqueous liquid containing a nitrogenous organic base having a swelling action on the cellulose acetate and a water-soluble salt of an organic acid, said salt being one which is not a saponifying agent for the cellulose acetate and which diminishes the swelling of the cellulose acetate.

13. Process for the saponification of filaments, threads, yarns, fabrics and like materials having av basis of cellulose acetate, wherein saponification is effected by means of an aqueous liquid containing a nitrogenous organic base having a swelling action on the cellulose acetate and sodium acetate, the sodium acetate diminishing the swelling of the cellulose acetate.

14. Process for the saponification of filaments, threads, yarns, fabrics and like materials having a basis of cellulose acetate, wherein saponification is effected by means of an aqueous liquid containing monomethylamine which has a swelling action on the cellulose acetate and sodium acetate, the sodium acetate diminishing the swelling of the cellulose acetate.

15. Process for the saponification of filaments, threads, yarns, fabrics and like materials having a basis of cellulose acetate, wherein saponification is effected by means of an aqueous liquid containing ethylene diamine which has a swelling action on the cellulose acetate and sodium acetate, the sodium acetate diminishing the swelling of the cellulose acetate. 4

HENRY DREYFUS. ROBERT WIGHTON MONCRIEFF. FRANK BREN'I'NALL HILL.