US1155102A - Process of bleaching. - Google Patents

Description

UNITED STATES PATENT oniuoE.

ROESSLER & HAssiZA 'FRIEDRICH LpDWIGisbg MIDT, OF CHARLOTTENBURG. GERMANY. AsstGNoR TO THE HER CHEMICAL COMPANY. A

CORPORATION OF NEW YORK.

PROCESS OF BLEACHING.

No Drawing. Original application filed January 25. 1910, Serial No. filed January 9, 1911.

To all H'lwm it may won/cm Be it known that I, Fnn-znuuru LL'owio Scnmirr. a citizen of the German Empire. residing at Charlottenburg, in said German lmpire, have invented certain new and useful Improvements inflProcesses of Bleaching, of which the following is a specification.

This invention relates to an improved process of bleaching by means of borates containing active oxygen in the presence of compounds of magnesium, of the alkaline earth metals and of zinc.

, Sodium perborate possesses the property of giving off its oxygen rather rapid y in water at a temperature as low as 50 C. This is a disadvantage in the applicationof sodium perborate as a bleaching agent, 1n-' asmuch as the washing and bleaching process can only properly begin at a higher temperature, so that a large proportion of the oxygen will be driven off and its effect lost before the efficient temperature is attained. In view of this fact, the discovery that magnesium perborate evolves its oxygen at a hi her temperature represented an advance.

It is known that mixtures of sodium per borate and a magnesium salt in equivalent proportions can be employed for bleaching, instead of pure magnesium perborate. In this case the magnesium perborate is formed from the sodium perborate and the magnesium salt by double decomposition. The proportions which are used in the latter process are such that the whole of the sodium perborate is decomposed by the magnesium salt. To this extent the latter process only differs from that with magnesium perborate in the fact that the magnesium perborate is produced by the saiddouble decomposition just before the bleachmg occurs.

While the employment of magnesium perborate for bleaching purposes represents an advance as regards the bleaching effect.

owing to the greater stability of the magnesium perborate under boiling, yet, on the other hand, its high price and some other shortcomings militate against its wide employment.

I have now found that it is possible to obtain the effect of greater resistance to boiling with the cheap sodium pcrborate and with other alkali metal perboratcs containing active oxygen, by adding certain substances to the same. To these substances be- Specification of Letters Patent.

Patented Sept. 28. 191?.

540,044. Divided Serial No. 601,695.

and this application long also the salts of magnesimu and their the above-mentioned processaccording to which sodium perbi'i'rate is completehfdecomposed by equivalent proportions of magnesium salt.

I have found that it is not necessary to add to the alkali metal perborate so much magnesiumcompound that the whole bleachrg process is carried out with magnesium perborate, that is to say. that all the sodium perborate is decomposed by the magnesium salt. ()n the contrary, I have found that it is possible to attain the said effect of greater resistance to boiling with only very small proportions of an addition of a magnesium compound. For example, the addition ofa fraction of amolecular proportion suliices to attain a very distinct effect, as will up pear from the following: A one per cent. solution of sodium perborate, heated to -80 C. was found after a few minutes to have lost half of its active oxvgen and after twenty-live minutes only 10 per cent. of the oxygen remained. When one-sixth of a molecular proportion of magnesium sulfate is added to one molecular proportion of sodium perborate, dissolved toa one per cent. solution, about 98 per cent. of the ac the oxygen remainsafter twenty-five minutes heatin to 7080. When under the same conditions one-twelfth of a molecular proportion of magnesium sulfate is added, the effect of this-addition is that after twenty -five minutes heating to the same temperature, about per cent. of the oxygen remains. The addition of one-sixtieth of a molecular proportion of magnesium sulfate under exactly the same conditions has the effect that about 70 per cent. of the oxygen remains after the sameperiod. It follows from these examples that in order'to attain a higher resistance to boiling, it is not necessary to convert the alkali metal perborate completely into magnesium perborate, but, on the contrary. a very small molecular proportion of magnesium salt suflices. This action of less than equivalent proportions of magnesium salt was not to be foreseen, for inl. the new process, in which the greater pdrtion of the sodium perborate remains unaltered in solution, the natural assumption would therefore be that this unaltered sodium perborate would split the oxygen just as readily as do ordinary solutions of sodium perborate.

The new process utilizing only small quantities of magnesium salt is of special importance on account of its technical advantage over the known process using either ready prepared magnesium perborate or freshly formed magnesium perborate. Both magnesium perborate and the magnesium borate into which theforrner becomes congifted after the bleaching action are insolue. liquor a considerable quantity of such magnesium precipitate, which, owing to the large quantity present, has a detrimental effeet and is diiiicult to remove from the bleachedgoods. By using smaller quantities of'magnesium salt, far less of this troublesome precipitate has to be dealt with,

- and the less the quantity of magnesium salt and the remaining oxygen beinf: n'l'easured after twenty-live minutes: The addition of one-sixth of a molecular proportion of chlorid of calcium is found to make the solution stable up to about 87 per cent, while one-fiftieth of a molecular proportion of chlorid of *alciuni is found to give a stabilityof about 50 per cent. One-lifteenth of a. molecular proportion of Strontium chlorid gives about 90 per cent. stability, oue-' twelfth of a molecular proportion of barium chlorid about 50 per cent. stability.

The following is an example of the bleaching process as carried out by-borates containing active oxygen: 200 kilograms of cotton, which is freed in the well-known manner by boiling it with caustic soda from the pectin compounds, is treated with a solu tion' of 2,000 liters of water containing 10 kilos of caustic soda, 5 kilos of soap, 1.5

kilos of sodiumperborate, and 0.2 kilo of crystallized magnesium sulfate, for about live hours in an open vessel, or for from three to four hours under pressure at a temperature of 110 0., under continuous stirring of the mass. After cooling the bleached cotton is separated from the bleaching liquor, washed and dried.

There is therefore in the bleaching perborate crystallized calcium chlorid, or 0.2? kilo or r talliaed strontium chlorid, or 0.25 kilo c tallized barium chlorid. The quantities or these substances can be increased or creased. in the place of caustic soda, other alkaline substances, as, for instance, or Turkey-red oil, can be used. In place cotton, other vegetable fibers, such as liner can be treated with advantage by the innproved bleaching substances, and also test tile fabrics. I

The fixing effect of the said substances J5 applies not only to sodium perhorate, but also to the other borates containing active oxygen, which can be obtained by crystall zation or by mixing or melting. The c obtained also applies to mixtures it with other substances not having a. coat action. The said fixing substances added to the active borates and handled or mixture. of both of them, ready iror use an be placed upon the market, or the procedure may be such that they are added just before use 0 during use. i

It is not even necessary that the salts or bases ha ring an action in the described sense shall be of the ordinary kind; for example, the persalts and peroxids oi' the same will serve the purpose.

I wish to heunderstood that the term is also to embraceother borates containing active oxygen, as for stance pcrborax and such boratcs, containins, active oxygen, as manufactured by the process covered U. S. Patent No. 1,006,798 issued to me.

Having thus describedmy invention, 1 claim has new and desire to secure by Letters Patent:

1. The process herein described of Wash ing and bleaching fibers by means of a pen borate, which consists in applying; the same to the fibers in the presence, of a soluble inorgauic compound of mamiesium in-a less than equivalent proportion.

52. The process herein described of washing and bleaching fibers by means a pen borate which consists in applying the some to the fibers in the presence of a. soluble. 3" organic compound of an alkali earth me. in a less than equivalent proportion.

In testimony,that I claim the foregoingas my invention, l have signed my name in presence of two subscribing witnesses.

FRlEDRICll LUDWIG SCHMIDT.

Witnesses:

Rmnnonn Gunner, v Max h'lxn'rsclnui.