US3005779A

US3005779A - Process for the optical brightening of polyacrylonitrile fibers

Info

Publication number: US3005779A
Application number: US831067A
Authority: US
Inventors: Ackermann Franz; Siegrist Adolf Emil
Original assignee: Ciba AG
Current assignee: BASF Schweiz AG
Priority date: 1955-02-15
Filing date: 1959-08-03
Publication date: 1961-10-24
Anticipated expiration: 1978-10-24
Also published as: FR1146154A; CH333182A; US2977319A; DE1114461B; BE545228A; GB828545A; NL94570C

Description

United States Patent 3,005,779 PROCESS FOR THE OPTICAL BRIGHTENING F POLYACRYLONITRILE FIBERS Franz Ackermann, Binningen, and Adolf Emil Siegrist, Basel, Switzerland, assignors to Ciba Limited, Basel, Switzerland No Drawing. Filed Aug. 3, 1959, Ser. No. 831,067 Claims priority, application Switzerland Feb. 15, 1955 17 Claims. (Cl. 252-3012) 1 This is a continuation-in-part of our copending patent application Serial No. 563,457, now US. Patent No. 2,977,319 filed February 6, 1956. i

The invention relates to a process for the optical brightening of polyacrylonitrile fibers which comprises treating said fibers with a compound of the formula wherein X and X each represents a member selected from the group consisting of a hydrogen atom, a chlorine atom and a lower alkyl group having at most 3 carbon atoms and Y and Y each. represents a member selected (2) N p N\ v CCH=CHC/ N N l i The present invention relates further to a composition of matter substantially consisting of polyacrylonitrile fibers having incorporated a small quantity of an optical brightening agent of the general Formula 1 or of the Formula 2.

The 2:S-di-[benzimidazyl-(Z)]-furans of the general Formula 1 can be made by heating an ortho-diamine of the benzene series, of which one amino group is primary and the other amino group is at most secondary and which may contain a chlorine atom or an alkyl group of low molecular weight in the benzene nucleus, with furan- 2:5-dicarboxylic acid, and, when the ortho-diamine used as starting material contains two primary amino groups, if desired, treating the resulting 2:5-di[benzimidazyl- (2') ]-furan with an alkylating hydroxyalkylating, alkenylating or aralkylating agent.

The reaction is advantageously carried out at a temperature of at least 190 C. However, the dibenzimidazylfurans can also be obtained, as described for the known compound in US. Patent No. 2,463,264 patented March 1, 1949 by Charles Greanacher et a1., by reacting the components together at a temperature below 190 C., for example, at about 150 C., but substantially lower yields are obtained.

In general, the two starting materials are advantageously used for the reaction in at least approximately the theoretical proportions, that is to say, that for every molecular proportion of furan dicarboxylic acid there are used 2 molecular proportions or an amount at most a mixing them together in the solid state.

few percent more or less than 2 molecular proportions;

of the. diamine. While the reaction can be carried out in a suitable high boiling solvent, this usually leads to less satisfactory results than'when the reaction mixture consists solely of the two starting materials and, if desired, a small proportion of boric acid.

The i presence of boric acid increases the yield quite considerably. The proportion of boric acid is advantageously about 0.5% to 5% calculated on the total weight of the reaction mixture.

Furthermore, it is of advantage to carry out the reaction in the absence of oxygen (air), for example, in vacuo or advantageously in an inert gas, such as nitrogen.

The procedure may, for example, consist in heating together the two starting materials at about 140 to 150 C.

in the presence or absence of boric acid, if desired, after The resulting melt is then gradually raised to about 200 C. While thus increasing the temperature, the elimination of water sets in. The period during which the temperature is raised from 140 C. to about 200 C. should not be too long,

- as otherwise there is a risk of the melt thickening or'even 5 organic solvent, precipitating the imidazole in'the form of a salt, which is usually sparingly soluble in water, by adding a dilute mineral acid, for example, sulfuric acid or hydrochloric acid, and then separating the salt from the aqueous solution;' From the salt the base can be liberated with the aid of an alkali, such as an alkali metal carbonate or ammonia.

Instead of using as starting materials for the manufacture of the furan compounds substituted at the imidazole nitrogen atoms, for example, those of Formula 1,

' diamines which contain a secondary amino group, the

substituents in question (Y and/or Y see above) may be subsequently introduced into 2:5-di- [benzimidazyl- (2')]-furans unsubstituted at the imidazole' nitrogen atoms, and one or both of the hydrogen atoms bound to nitrogen may be thus exchanged for substituents.

= The material to be improved by the use of the present process can exist in any stage of processing, it being obviously advantageous to treat it in the described manner at a stage when all other treatments have been completed 1 which would have-the eifect of removing again the agent used according to the invention or would have an un-- favorable effect upon it. The agents used can for exam-' ple be added to the materials to be improved either before or during the shaping thereof. Thus they can be dissolved or finely distributed in a spinning mass before the spinning thereof.

Fibers can be used in the application of the present process which either consist of polyacrylonitrile alone orof fiber mixtures consisting to a substantial extent of polyac'rylonitrile fibers, or of fibers consisting of copolymers containing other compounds in addition to polyacrylonitn'le. r

" Especially valuable results are generally obtained with those 2,5-di-[benzimidazyl-(2)]-furans of the general Formula 1 whose benzene radicals are substituted by low present process which can exist as staple fibers or mono- Patented Oct. 24, 19.61-

dissolved or suspended. If desireddispersing agents can.

be added in the'treatment for example soaps, polyglycol ethers of fatty alcohols or fatty amines, ,cellulose 'sulfite waste liquor or condensation products with formaldehyde of naphthalene sulfonic acids which may be alkylated.

It is of particular advantage, especially when the treatment of the fibers is exclusively for the purpose of proving the optical properties, to work in weakly alkaline o i b h p efe a y weakly ac ba hs, f xamp containing acetic acid or formic acid. It is likewise of advantage if the treatment takes place at elevated temperature, for example at the boiling temperature of the bath or in the neighbourhood thereof (about 90 ;C It is surprising that the compounds of the composition set forth above possess a good affinity for the fibers and can be fixed thereon in a similar manner to dyestuifs. In this connection it may be remarked that in the case of these synthetic fibers many optical improving and ri n n a en w h a 9 oo ap l s b li v o other fiber materials, cannot be .used for the reason that in this ease they cannot be fixed on the fiber or do not give rise to the desired efiect. The fastness to light of the materials treated according to the present process is also good, the efiect persisting even after long exposure to ht- The quantity of the improving agent to be used, calr culated on the material to be treated, can vary within wide limits. Even with very small quantities, in some cases for example, of 0.01 percent, a distinct and permanent eifect can be attained. Althoughquantities of more than about 3 percent are in general not disadvantageous, they offer no advantages compared with the normal quantities.

As indicated above, the present process can advantageously be combined witth other processing methods. Thus the compounds to be used according to the present invention can also be applied as follows:

(a) In admixture with dyestuffs or as additions to .dyebaths ,or printing, discharge or reserve pastes. Further also for the after-treatment of dyeings, prints or discharge prints, especially in the soaping process. Thus, for ex,- ample, polyacrylonitrile fibers can be simultaneously dyed and improved as regards optical properties in an acid medium and are dyed in the same bath with azo dyestuifs which are free from sulfonic acid groups and w ic c ai as sa ups m no g oup sa form with acids in an acid medium salts which at the most are partially hydrolyzable, these dyestuffs being fixed on the fiber in the form of-their salts.

(b) In ad i tu e with chem a b each n a nt o as additions to bleaching baths.

c m ti n w a h n n s; Th s in agents and brightening agents can be separately added to the washing baths to be used. It is also advantageous to use a i g age w c on r h nin a ents dmixed therewith. A s washing agents are suitable for amp s ap (s d s t .1" hi he fatty as dfl a t of sulfonate washing agents, as for example, ofsulfonated benzimidazoles substituted on the Z-carbon atom by higher alkyl radicals, also salts of monocarboxylic acid esters of 4-sulfophthalic acid with higher fatty alcohols or salts .of fatty alcohol sulfonates, alhylaryl sulfonic acids or condensation products of higher fatty acids with aliphatic hydroxyor amino-sulfonic acids. Non-ionic washing agents can also be used, for example polyglycol ethers which are derived from ethylene oxide and higher fatty alcohols, alkyl phenols or fatty amines.

The washing agents of the above specified type can also contain the customary washing agent additions, such as alkali metal carbonates, phosphates, pyrophosphates, polyphosphates, metaphosphates, silicates, perborates or psr ar nst s ens a he b shteains sls a ask treated material.

patible with such additions. It is also possible to prepare washing agents which consist solely or for the most part of inorganic compounds of cleansing effect and the brightening agents. The production of the mixtures of the washing agents and optical brightening agents takes place in a simple manner by mixing and/or grinding of the components together. In this case it may be of advantage to use or the other component in the dissolved or molten condition for the purpose of facilitating distribution.

In general a small addition of the optical improving agents to the washing agents suffices. There are .concerned, for example, quantities of 0.1 to 5 percent calculated on the washing agent. Also smaller quantities, for example, 0.01 percent or even less can be added. Also mixtures with other known brightening agents can be usedf The washing agents are used asin the customary washing processes. In this manner materials to be cleansed canbe simultaneously washed and brightened. Whenthe present process is combined with other treatment or improvement methods, for example those set forth above under (a) to (c), the combined treatment advantageously takes place with the aid of suitable con stituted preparation. These stable preparations are characterized by a content of imidazoles of the type specified above, and also further textile treating agents, for example dyestuffs, chemical bleaching agents, finishing agents or especially washing agents.

The following examples illustrate the invention, the p t a d Pers t s s ng b Weight unl s qth w s stated.

E a p 1 Polyacrylonitrile fabric, for example "-Orlon is treated at a bath ratio 1:50 with 0.01 percent of 2:5-di- [benzimidazyl-(2')]-furan for 30 minutes at about90 C. in a 'bath containing per liter 1 gram of percent formic acid. The material is then rinsed and dried. The resulting material \possessesa higher white content than the un- Similar eifects are obtained when instead of 2:5-di-[benzimidazyl (2')] furan the diimidazoles of the following formulae are used:

(3) /N HC CH N\ \s H/ Y\ O N N lHs (4) /N HC CH or when .the :B-diibenzimidaayl-(Z')Lethylene is used. The 2:;5-di- [benzimidazyl-(2')] furan can be prepared in the following manner:

108 parts of 1:2-diaminobenzene, 78 parts of pure furan- 2 :5 .-dicarboxylic acid and 3 parts of boric acid are t r d or 70 m nu es t 2- 6" in a we: O n ssnh tem e atu is hen a ed w thin 30 m was t 0 hich ca s l w el mina ion we. The mixture is then stirred for 1 ,hO r at 210 to 220 C.

150 parts of glycol are then added, whereupon the temperature drops to 150 C. Immediately afterwards, 1000 parts of 2 N-hydrochloric acid are added, and the mixture is stirred for /2 hour at C., allowed to cool, suctionfiltered, and the filter cake is washed three times with 300 parts of water and then stirred for /z hour at 70 C. in 0 P rts of w t r qqnta fms 0 Pa t of mn s a Q 30% strength. The yellow condensation product is allowed to cool to room temperature, suction-filtered and washed three times with 300 parts of water. After drying, about 105 parts of the condensation product of the formula I H -o (3-0 melting at 292.5-294 C. are obtained.

The water of crystallization can be removed by heating the product for 30 minutes at 230 C. under a pressure of 0.01 mm. Hg. The dehydrated product yields the following data:

Calculated: C, 71.99%;H, 4.03%;N, 18.66%. Found: C, 71.79%; H, 4.18%; N, 18.76%.

When the process described above is performed without the addition of boricacid, the yield obtained is by a few percent lower.

The compound of Formula 3 can be prepared in the following manner:

15 parts of 2:5-di-[benzimidazyl-(2')]-furan are dissolved in 80 parts of ethanol of 90% strength containing 8 parts of sodium hydroxide. A solution of 12.5 parts of dimethyl sulfate in 10 parts of'ethanol is then stirred in at 75 C. dropwise in the course of 2 hours. The temperature of 75 C. is maintained for another hour, the solution is poured into 1000 parts of Water, the precipitate is suctioned off and dried and yields about 14 parts of the compound of the Formula 3.

After having been recrystallized three times from aque ous ethanol, the product melts at 146-147 C. and gives the following analytical data:

C ,,H ON Calculated-C, 69.35%; Found-C, 69.24%; H, 4.95%.

The compound of the Formula 4 can be prepared in the following manner:

15.2 parts of 2:5-di-[benzimidazyl-(2')]-furan are dissolved in 100 parts of 90% ethyl alcohol containing 6 parts of caustic soda. 8.2 parts of benzyl chloride are added with stirring in the course of 2 hours at a temperature of 75 C. The mixture is stirred for one hour, then poured onto water and the crystalline product is suctionfiltered. The yield is 18.8 parts.

After recrystallization from aqueous ethanol the product melts with decomposition at about 250 C.

The mfl-di-[benzimidazyl-(Z)J-ethylene can be prepared in the following manner:

660 parts of o-phenylene diamine are heated with 116 parts of fumaric acid within 3 to 5 hours from 120 to 160 C. with the exclusionof air. As soon as the elimination of water subsides, the temperature is raised to about 190 C. and maintained for a short time until water no longer escapes. The whole is allowed to cool and the o-phenylene diamine in excess removed by extraction with alcohol, benzene or another solvent. The residue is dissolved in hot dilute hydrochloric acid and the condensation product precipitated from the solution by means of an alkaline agent, e.g. with ammonia, filtered and washed neutral with Water.

Example 2 Polyacrylonitrile fabric (Orlon) is treated at a bath ratio 1:40 with 0.03 percent, of 2:5-di- [benzimidazyl- (2')]-furan for 1 hour at about 95 C. in a bath containing per liter 5 g. of 85 percent formic acid and 5 g. of an addition product from about 30 mols of ethylene oxide to a mixture of saturated fatty alcohols the majority of which has 18 carbon atoms. The material is then rinsed and dried. The resulting material possesses a higher white content than the untreated material.

Similar eiiects are obtained when instead of 2:5-di- 6 [benzimidazyl-(2') J-fur-an a dimidazole of the Formula 2, 3 or 4 is used.

Example 3 I Polyacrylonitrile fabric, for example Orlon is treated at a bath ratio 1:40 with 0.03% of the compound of the formula in a bath containing per liter 1 gram of formic acid, 2 grams of sodium chlorite and 2 grams of sodium nitrate. The material is then rinsed and dried. The resulting material possesses a higher white content than the untreated material.

Similar effects are obtained, when instead of the compound (6) the following eompound is used:

(7) N HO OH N afa/ t \6/ N N JaHs aHs The compound of Formula 6 can be prepared in the following manner:

10' parts of 2:5-di[benzimidazyl-(2')]-fi1ran are dissolved in 70 parts of ethanol of strength containing 8 parts of sodium hydroxide. A solution of 6 parts of l-chloro-Z:3-di-hydroxypropane in 10 parts of ethanol is then stirred in dropwise at 75 C. in the course of 2 hours. The temperature of 75 C. is maintained for another hour, and the solution is then poured into 500 parts of water, and the precipitate is suctioned off and dried,. to yield about 12 parts of the condensation product'of theFormuila 6. t

After having been recrystallized three times from aqueous ethanol, the product melts at 2905-291" C. and gives the following analytical data:

C H O N CalculatedC, 54.21%; H, 5.13%:N, 14.37%. FoundC, 64.58%; H, 5.50%; N, 14.28%.

When 13 parts of l-bromo-propylene-(Z) .are used in-- stead of 6 parts of l-chloro-2:3-dihydroxypropane, the condensation with furan dicarboxylic acid yields about 15 parts of the compound of the Formula 7.

After having been recrystallized five from aqueous dimethyl formamide, the product-melts at 2985- 300 C. and yields the following analytical data:

C24H2403N4Z Calculated-C, H, 5.77%. FoundC, 69.22%; H, 5.60%.

Example 4 1500 cc. water 3 grams formic acid 85%.

3 grams sodium chlorite 0.1 gram of the above product,

then rinsed and dried. The material thus treated is whiter than a material which has been treated without the addition of the above product.

Similar elfects are obtained when instead of the 2:5-di

[benzi'rnidazyl-(Z') I-furan adimidazol'e of any of the following formulae is used:

or when the azfl-di-[benzimidazyhfl'Methylene is used.

The compound of Formula 8 can be prepared in the following manner:

15 pants of 2z5-di-[benzimidazyl-(2')]-furan are dissolvedin SO-parts. of ethanol of 90% strength containing 8 parts of sodium hydroxide. At the boiling temperature of ethanol a solution of 6 parts. of l-chloro-Z-hydroxyethanein. parts ofethanolv is added: drop-wise in the courseof 1 hours. The solution; is stirred for /2 hour at: 70 C. and then poured. into 500 parts of water. The

precipitated condensation product is. auctioned off and dried, to. yield about 16 parts; of the compound of the FOI'm1l1-h:8..

.After: having been. recrystallized three times from aqueousethanol; theproduct melts at 182l8.2.8 C.

C20H16O2N4I Ca1culated-C, H, N, 16.27%.. FoundC; 69;80%; H,.4.66%; N, 16.49%.

W116Il16 partsof l-chloro-2ehydroxypropane are used instead of 6 parts of l-chloro-Z-hydroxyethane the condensati'on with thefuran-dicarboxylic acid yields. about 11 partsof" the compound of the Formula 9. Melting point: 150 151. C..

The compoundtof; the'Formula. 10 can be prepared in the followingmannere- 10 parts of 4-chloro-l,Z-diamino-benZene, 5.6 parts of 2:5'-furan.-dicarboxylic acid and0.2 part. ofv boric acid are heated=with stirringto2l0 C. in a currentof nitrogen for 90 minutes, the mixture thickens, after 30 minutes and solidifies after 45 minutes.- The melt iszdissolvedby. adding 20 parts of glycol, poured ontowater andi suction-filtered. The yield is about 9 parts.

After having been recrystallized three times from aqueous-ethanol, the.pro.duc t melts at 306; to 307.5 C.

Example 5 A soap is;pro ducedwhichcontains l percent-of 2:5-di- [benzimidazyl7(2: )7J-fUIaIl. Polyacrylonitrile fibers, for example *Qrlon, which have,-beenwashed with this soap, have a brighter appearance-than material which has only been washed with usual soap.

A similar efiect is achieved when instead of soap a synthetic washing material is used or one of the following composition:

33.3% of soap 111098 of anhydrous'sodium carbonatel4.0% of sodiumpyrophosphate 7.0% of sodium perborate 3 .0%- of-magnesium: silicate following formulae are used in the washing agent:

or the; mddi-[benzimidazyl-(Z')]ethylene is used. The compounds (10) and (11) can be prepared as follows:

24.4 partsof 4-methyl-l:Z-diaminobenzene, 15.6 parts of furan-ZzS-dicarboxylic acid and 0.5 part of boric. acid are: fused at l45'l50 Cr in a currentof nitrogen. The temperature is then raised to 210-215" C. and: the melt isstirred on; for 2 hours at this temperature. 40 parts of glycol arethen added to the melt, whereupon the temperature drops to 150:" C. The melt iscooled to 100 C. and: 200 parts'of 2- N-hydrochloric. acid are added. The mixture is then stirred for' /2 hour at C.,v cooled to room,

temperature, suction-filtered, and the. filter cakeiswashed three times with 60 parts of water. The filter residue is then stirred for /2w hour at 70 C. in 200! parts of water containing 15 parts of ammonia of 30% strength. The yellow condensation product isallowed to cool to room temperature, suction-filtered and the filter cake is washed three times with 60 parts of water.. After drying, about 24- parts of 2:S-di-[6-methylrbenzimidazyl-(2f)] -furan are obtained. After having been recrystallized twice from aqueous ethanol, the product is analyzed and. yieldsthe following data:

8; parts of 2:.5-di-[6'-rnethyl-benzimidazyl (2)' ]:-furau obtained .asdescribed. above are dissolvedin 50 parts of ethanol of 90% strength containing 4 partsof sodium hydroxide.v A solution of 6 partsof. dimethyl. sulfate. in 10 parts of ethanol is thenaddeddropwise at 75 C..-in, the course of 1 hour. Thesolution isstirred-for. another- /2 hour at that temperature andthen poured into. 500' parts. of water,.and the precipitate-issuctioned off andLdriecL-toyield about6 parts of the compoundoftheFormula l0 and-2 parts of the Formula 11.

The product substituted at both nitrogen atoms melts at 236237.5 C., whereas the product substituted atlonly one nitrogen atom melts at 272272..5 C

Example. 6

Orion fabric is treated" for 1 hour at 90j-100 C;,in a bath which contains (calculated on the fabric) 1% of the dyestuff of the. formula 3% 2:5-di- [benzimidazyl-(Z)]-furan and-3%. acetic acid of 86% strength. (Ratio of goods to.liquor-. 1440.).-

After being rinsed and dried the fabric-so treated has a. pure greenish blue shade.

Similar effects are obtained, when instead of 2:5'-di- [benzimidazyl=(2) ]-furan .acompound Ofithe; Formula 8 or 9 is used, or when the compound of the Formula 2'is used.

Fabric dyed in the same manner but without the addition of the di-imidazole compounds is less pure in color and less greenish.

Example 7 of the compound of Formula 8 a compound of Formula 4 or 6 is used, or when the compound of the Formula 2 is used. 7

Example 8 30 parts of 2,5-di-[benzimidazyl-(2') J-furan are ground to a fine, homogenous powder in a suitable mixing and grinding apparatus, with 60 parts of sodium bisulfate and 910 parts of a condensation product of "naphthalene sulfonic acid and formaldehyde.

Polyacrylonitrile fibers, for example Orlon, are treated for 30 minutes at 90-95 C. at abath ratio of 1:30 with 0.5 percent of this powder in a bath which contains 1.5 grams per liter of 85 percent formic acid, then rinsed and dried. The Orlon fiber thus treated has a higher white content than the untreated material.

Similar brightening effects are obtained when a compound of the Formula 2, 6 or 9 is used instead of 2:5-di- [benzimidazyl-(Z') -furan.

What is claimed is:

1. A process for the optical brightening of Polyacrylonitrile fibers which comprises applying to said fibers in aqueous medium from 0.01 to 3.0 percent, calculatedjon the weight of said fibers, of a compound of the formula wherein X and X each represents a member selected from the group consisting of a hydrogen atom, a chlorine atom and a lower alkyl group having at most 3 carbon atoms and Y and. Y each represents a member selected from the group consisting of a hydrogen atom, a lower alkyl group having at most 3 carbon atoms, a lower alkenyl group having at most 3 carbon atoms, a lower mono-hydroxy alkyl group having at most 3 carbon atoms, a lower di-hydroxy alkyl group having at most 3 carbon atoms and a benzyl radical.

2. A process for the optical brighteningof polyacrylonitrile fibers which comprises applying to said fibers in aqueous medium in a'finely dispersed state from 0.01 to 3.0 percent, calculated on the weight or said fibers, of

an optical brightening agent of the formula wherein X and X each represents a. member selecteu from the group consisting of a hydrogen atom, a chlorine atom and a loweralkyl group having at most 3 carbon atoms and Y and Y each represents a member selected from the group consisting of a hydrogen atom, a lower alkyl group having at most 3 carbon atoms, a lower alkenyl group having at most 3 carbon atoms, a lower mono-hydroxy alkyl group having at most 3 carbon atoms, a lower di-hydroxy alkyl group having at most 3 carbon atoms and a benzyl radical.

lab

10 3."A process for the optical brightening'of'polyacrylonitrile fibers which comprises applying to said fibers in aqueous medium in the presence of a dispersing agent from'0'.01 to 3.0 percent, calculated on the weight of said fibers, of an optical brightening agent of the formula 1v l i. wherein X and X each represent a member selected from the'groutp consistingof a hydrogen 'atom,a chlorine atom and a lower alkyl group having at most 3 carbon atoms and Y and Y each represents a member selected from the group consisting of a hydrogen atom, a lower alkyl group having at most 3 carbon atoms, a lower alkenyl group having at most 3 carbon atoms, a lower mono-hydroxy alkyl group having at most 3 carbon atoms, a lower di-hydroxy alkyl group having at most 3 carbon atoms and a benzyl radical. V I

4. A process for the optical brightening of polyacrylonitrile fibers which comprises applying to said fibers in aqueous medium in the presence of a washing agent from 0.01 to 3.0 percent, calculated on the weight of said fibers, of an optical brightening agent of the formula wherein X and X each represents a member selected from the group consisting of a hydrogen atom, a chlorine atom and a lower alkyl group having at most 3 carbon atoms and Y and Y each represents a member selected from the group consisting of a hydrogen atom, a lower alkyl grouphaving at most 3 carbon atoms, a lower alkenyl group having at most 3 carbon atoms, a lower'mono-hydroxy alkyl group having at most 3 carbon atoms, a lower di-hydroxy alkyl group having at most 3 carbon atoms and 'a benzyl radical.

'5. A process for the optical brightening of polyacrylonitrile fibers which comprises applying to said fibers in aqueous medium from 0.01 to 3.0 percent, calculated on the weight of said fibers, of the compound of the formula HCCH I oii i r-o CH N/ \O/ \N .1031,

\N I V I I 7. A process for the optical brightening of polyacrylonitrile fibers which comprises applying to said fibers in aqueous medium from 0.01 to 3.0;percent, calculated on the weight of said fibers, of the compound of the formula 11 8- .A pr es 9r the opt al bri htening o polva y ni i fi e s wh ch c mp se ppl in to a d zfibe s in. aque s m d um i om 01 i031 perc nt; ca c l d o the w ig t f id fibe s. of t compo nd o he o nml (EH: omen the weight of said fibers, of the compound of the formula 10. A composition .of matter substantially consisting ,of polyacrylonitrile fibers having incorporated therein an op.- tical brightening agent in a proportion sufficient to brighten said fibers, said optical brightening agent being of the formula N N HC-GH at ."H/

I o N N i ll wherein X and X1 ea h p esent amernher se ecte .from the oup co t g at a hyd ge a m a hlo in atom nd a lower alky g oup havin at mos 3 ca b n a om and Y and 1 ea h r prese ts a mem er se ecte m e group isti g of a hyd og n atom, a owe a kyl group avi g at m s 3 ca bon at ms, a lo e monoydroxy al y up having t m st 3 ca bon atoms, slow y y alkyl group ng a m t 3 arbon at ms and a benzyl radical.

11. A process for theoptical brightening of polyacry lor nitrile fibers which comprises applying to said fibers in aqueous medium from 70.01 to 3.0 percent, calculated on the weight of said fibers, of the optical brightening agent of the formula 12. A process for the optical brightening of polyacrylonitrile fibers which comprises .applying to said fibers in aqueous medium in a finely dispersed state from 0.01 to 3.0 percent, calculated on the weight of said fibers, of the optical brightening agent of the formula 13. A process for the optical brightening of polyacrylonitrile fibers which comprises applying to said fibers in aqueous medium in the presence .9; a dispersing agent 12 from 0.01 to 3.0 percent, calculated onthe Weight of said fibers, of the optical brightening agent of the formula 14. A process for the optical brightening of polyacrylopitrile fibers which comprises applying to said fibers in aqueous medium in the presence of a washing agent from 0.01 to 3.0 percent, calculated on the weight of said fibers, of the optical brightening agent of the formula 15 A composition of matter substantially consisting of polyacrylonitrile fibers having incorporated therein an optical brightening agent in a proportion sufiicient to brighten said fibers, said optical brightening agent being of the formula 16. A process for the optical brightening of polyacrylo- 1 nitrile fibers which comprises applying to said fibers in and a compound of'the formula w e n X d 1 ea rep esents a member selec fromthe group consisting of a hydrogen atom, a chlorine atom and a lower alkyl group having at most 3 carbon atoms and Y and Y each represents a member selected from the group consisting of a hydrogen atom, a lower alkyl group having at most 3 carbon atoms, a lower alkenyl group having atmost 3 carbon atoms, a lower mqnohydroxy alkyl group having at most 3 carbon atoms a lower di-hydrogry alkyl group having at most 3 carbon atoms and a benzyl radical.

17. A composition of matter substantially consisting of polyacrylonitrile fibers having incorporated therein an optical brightening agent in a proportion sufiicient to brighten said fibers, said optical brightening agent being selected from the group consisting of the compound of the formula and a compound of the formula wherein X and X each represents a member selected from the group consisting of a hydrogen atom, a chlorine atom and a lower alkyl group having at most 3 carbon atoms and Y and Y each represents a member selected from the group consisting of a hydrogen atom, a lower alkyl group having at most 3 carbon atoms, a lower alkenyl group having at most 3 carbon atoms, a lower mono-hydroxy alkyl group having at most 3 carbon atoms, a lower di-hydroxy alkyl group having at most 3 carbon atoms and a benzyl radical.

References Cited in the file of this patent UNITED STATES PATENTS 2,463,264 Graenacher et a1. Mar. 1, 1949 5 2,488,094 Graenacher et a1. Nov. 15, 1949 2,604,454 Ackermann July 22, 1952 2,773,869 Leavitt Dec. 11, 1956 2,838,504 Crounse June 10, 1958 2,875,089 Ackermann Feb. 24, 1959 OTHER REFERENCES Dorman et al.: Relationship Between Structure of Dyes and Their Dyeing Characteristics on Hydrophobic 15 Fibers, American Dyestufl Reporter, July 5, 1954; pages Patent No, 3,005, 779 October 24,, *19-61 Franz Ackermann et a1.

It is hereby certified that er ent requiring correction and that t corrected below.

ror appears in the above numbered pathe said Letters Patent should read as Column 4, line 8, for "preparation?" 12, formula (5) t as shown below in after "use" insert one line 23, read preparations column 5, lines 6 to he center portion of the formula should appear stead of as in the patent:

' HC CH I I Signed and sealed this 15th day of May 1962.

(SEAL) Attest: ERNEST W, SWIDER Commissioner of Patents

Claims

16. A PROCESS FOR THE OPTICAL BRIGHTENING OF POLYACRYLONITRILE FIBERS WHICH COMPRISES APPLYING TO SAID FIBERS IN AQUEOUS MEDIUM FROM 0.01 TO 3.0 PERCENT, CALCULATED ON THE WEIGHT OF SAID FIBERS, OF A MEMBER SELECTED FROM THE GROUP CONSISTING OF THE COMPOUND OF THE FORMULA