CH412316A - Use of stilbenic compounds to make objects fluorescent - Google Patents

Description

  

  



  Use of stilbenic compounds to make objects fluorescent
 The present invention relates to the use of novel fluorescent stilbenic compounds of formula:
EMI1.1
 in which R represents a substituted 4, 4'-stilbene radical and R 'identical or different hydrogen atoms or substituents, to make objects or articles fluorescent, characterized by the incorporation of these compounds in the objects or articles or their application to the objects or articles.



   These new compounds are therefore 4, 4'-benzoxazolyl-stilbenes. Compounds of this class exhibit fluorescence which makes them very useful as brighteners or optical brighteners. In addition, they exhibit a number of other properties such as high heat and light stability, high resistance to bleaching agents and customary textile treatments, etc., which make them brightening agents. and optical brightening which are very interesting for being incorporated into the spinning masses of synthetic textile fibers, in particular linear polyester.



   In general formula (I), R is a 4, 4 'divalent stilbene radical of general formula:
EMI1.2
 where R 'has the meaning already indicated and where Y and Y' are hydrogen atoms or identical or different substituents. The choice of the substituents R ',
Y and Y 'in formulas (I) and (II) is only limited by the sole condition that these substituents do not adversely affect the fluorescence properties of the compounds.



   The Y and Y 'substituents can, for example, consist of alkyl, aryl or cyano groups.



  When Y or Y is an alkyl group, this group preferably comprises from one to eighteen carbon atoms and this can be, for example a methyl, ethyl, n-butyl, isobutyl, 2-ethyl-hexyl group. , npentyl, n-hexyl, n-decyl, dodecyl or cetyl.



   When Y or Y is an aryl group, it is preferably a mononuclear aryl group, for example a phenyl, methylphenyl, methoxyphenyl, ethylphenyl, chlorophenyl or bromophenyl group.



   Among the substituents R 'which may be used, there may be mentioned a halogen atom or an alkyl, aryl, substituted aryl, hydroxy, alkoxy, aryloxy, acyl, acyloxy, amino, substituted amino, quaternized ammonium, sulfo, substituted sulfonyl, sulf amyl, substituted sulfamyl, cyano, thiocyano, thiol, carbamyl, substituted carbamyl, carbamoyloxy or nitro.



   The halogen atom optionally represented by R ′ can be a chlorine, bromine, fluorine and iodine atom. When R ′ represents an alkyl group, this group preferably contains from one to eighteen carbon atoms and this can be, for example, a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl or n-pentyl group. , n-hexyl, n-decyl, n-dodecyl, n-hexadecyl or n-octadecyl. When R ′ is an aryl or substituted aryl group, it is preferably a mononuclear group, for example a phenyl, methylphenyl, Úthylphenyl, chlorophenyl, bromophÚnyl, methoxyphenyl, ÚthoxyphÚnyl or other substituted phenyl rings.

   However, R 'can also be an aryl ring such as 1-naphthyl or 2-naphthyl or a substitution derivative of this ring or a heterocyclic ring, such as a furyl ring, thienyl, etc. Examples of alkoxy groups represented by R ′ are constituted by those of those groups which contain from one to eighteen carbon atoms and, preferably, from one to four carbon atoms, for example the methoxy, groupesthoxy groups, propoxy, isopropoxy, n-butoxy, isobutoxy, n-amoxy, isoamoxy and hexoxy.

   Phenoxy and naphthoxy groups are examples of aryloxy groups represented by R '. Examples of acyl groups represented by R ′ are formyl, acetyl, propionyl, butyryl, isobutyryl, benzoyl and naphthoyl groups. Examples of acyloxy groups represented by R ′ are acetoxy, benzoxy, CHgCHaCOO-, CHgCHgCHaCOO- and CHCHCHCHCHCOO. Monoalkylamino or dialkyllamino groups where the alkyl groups are the same or different, arylamino, aralkyllamino, cycloalkyllamino, monohydroxyalkyllamino, dihydroxyalkyllamino, alkoxyalkylamino and other aliphatic amino groups are examples of substituted amino groups represented by R 'substituted amino groups.



  Normally, the alkyl, hydroxyalkyl or alkoxyalkyl groups forming part of these amino groups contain no more than four carbon atoms, but they may contain more.



   Examples of substituted sulfonyl groups represented by R ′ are alkylsulfonyl groups containing from one to eighteen carbon atoms and preferably from one to four carbon atoms, such as methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl groups. , etc., and arylsulfonyl groups, preferably mononuclear, such as phenylsulfonyl, methylphenylsulfonyl, chlorophenylsulfonyl or ethoxyphenylsulfonyl groups. Examples of substituted sulfamyl groups represented by R 'are alkylsulfamyl and dialkoylsulfamyl groups, such as N, N-dimethylsulfamyl, N, N-diÚthylsulfamyl, N, N-dipropylsulfamyl,

        N-ethyl-sulfamyl, N-methyl-sulfamyl, N-butyl-sulfamyl and N-ethyl-N-butyl-sulfamyl, arylsulfamyl and diarylsulfamyl groups such as N-phÚnyl-sulfamyl, N,
N-diphenyl-sulfamyl, N, N-diethyl-phenyl-sulfamyl, N-phenyl-N-ethyl-phenyl-sulfamyl, N, N-dibutyl-phylnyl-sulfamyl and N-ethoxy-phenyl-sulfamyl, and N groups -alkyl-N-aryl-sulfamyl, such as the N-Úthyl-N-phenyl-sulfamyl, N-methyl-N- (metoxyphenyl) -sulfamyl and N-butyl-N-chlorophenylsulfamyl groups.



   Among the substituted carbamyl groups represented by R ', there may be mentioned the alkylcarbamyl and dialkoylcarbamyl groups whose radicals contain from one to four carbon atoms, for example the N-methyl-carbamyl, N-ethyl-carbamyl groups,
N-propyl-carbamyl, N-isopropyl-carbamyl, N-butylcarbamyl, N, N-dimethyl-carbamyl, N, N-diethyl-carbamyl, N, N-dibutyl-carbamyl and N-ethyl-N-methyl- carbamyl, and arylcarbamyl and diarylcarbamyl groups, such as N-phenyl-carbamyl, N, N-diphenyl-carbamyl, N, N-di (ethylphenyl) -carbamyl and N,

   N-di 'tmethoxyphenyl) -carbamyl.



     R 'can also be one of the groups represented by the formulas:
EMI2.1


<tb> <SEP> / Q / Q / acyl / acyl / Q
<tb> -OC-N <SEP>; -NHS02Q <SEP>; -N, -N, -N <SEP>; -C-O <SEP> (<SEP> or-NHC-N
<tb> <SEP> II <SEP> \ <SEP> \ <SEP> \ <SEP> \ <SEP> II <SEP> II <SEP> \
<tb> <SEP> S <SEP> Qi <SEP> acyle <SEP> acyle <SEP> SO2Q <SEP> O
<tb> for example, those of those groups where Q and Q1 each represent a hydrogen atom, an alkyl group (preferably containing from one to four carbon atoms), a substituted alkyl group (preferably containing no more of four carbon atoms), an aryl group (for example phenyl, methylphenyl, ÚthylphÚnyl, methoxyphenyl, ethooxyphenyl, chlorophenyl or bromophenyl),

      or a cycloalkyl group (eg cyclobutyl, cyclopentyl or cyclohexyl).



   Unless otherwise indicated, the term acyl is used in a broad sense and embraces not only the acyl groups noted above, but also groups such as the ureido group, or groups
EMI2.2
 where Q and Q, have the meanings already indicated.



     R 'may also represent a fluorinated alkyl group containing from one to eighteen carbon atoms. The difluoroalkyl groups of formula - (CH), i CHF and trifluoroalkyl of formula (CH 3) nCF3 where n is a positive integer at most equal to 17 are representative of this class of substituents. Other higher fluorinated alkyl groups, for example of the formula - (CBL), (CFg) -CFg where is an integer less than 5 and / the number 1 or 2 may also be present.

   Examples of fluorinated alkyl groups which may be represented by R ′ are the 2, 2 difluoro-ethyl, 3, 3-difluoro-n-propyl, 4, 4-difluoron-butyl, 5, 5-difluoro-n-amyl groups. , 6, 6-difluoro-n-hexyl, 2, 2, 2-trifluoro-ethyl, 3, 3, 3-trifluoro-n-propyl, 4, 4, 4trifluoro-n-butyl, 5, 5, 5-trifluoro -n-amyl, 6, 6, 6-tri fluoro-n-hexyl, CH CHLCFS, CH3CH2CF2CF;
CH CH .. CHaCF7CFs, and CH7CH., CF7CF2CF.



     R ′ may also represent an unsaturated acyclic hydrocarbon radical, for example an allyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, isobutenyl or 1-isopente- group. nyle.



   Normally, at most one of the R 'substituents of each of the phenyl rings of the divalent 4,4'-stilbene radical is a group other than a hydrogen atom. It is often preferred to use the simpler 4, 4'-bis- (benzo-oxazol-2-yl) -stilbenes, because they are the cheapest, can be prepared most easily and in some cases , their properties as fluorescent brighteners are better than those of newer, more complex compounds.



   The compounds of formula (I) can be prepared by heating under vacuum a 4, 4'-bis- (2-hydroxyphenylcarbamoyl) -stilbene at a temperature of between 2000 and 4000 C, preferably at a temperature of between 3000 C and 350 "C, under a pressure of less than 0.675 bar. The starting 4, 4'-bis- (2-hydroxy-phenylcarbamoyl) -stilbenes can be prepared by reaction of the chloride of an acid 4, 4'-stil bene-dicarboxylic on an o-amino-phenol in the presence of a solvent such as dioxane.

   The chlorides of 4, 4'-stilbene-dicarboxylic acids are prepared by reacting a 4, 4'-stilbene-dicarboxylic acid with thionyl chloride and phosphorus pentachloride according to the method described by
Hager and colleagues, J. Amer. Chem. Soc. 68, 2167 (1946).



   Various methods exist for preparing the desired 4,4'-stilbene-dicarboxylic acid. One of these, described by Toland et al, J. Amer. Chem.



  Soc. 75, 2263 (1953) and US Pat. No. 2610191 filed September 26, 1949, is to react p-toluic acid with sulfur. Another method, described by Harris, J. Chem. .



  Soc. 690 (1947), consists in condensing a 4-bromo phenyl-acetate on a 4-bromo-benzaldehyde to obtain a 4, 4'-dibromo-stilbene-a.-carboxylic acid which is then converted to collect the acid 4 , 4 'stilbene-dicarboxylic desired. A third method consists in condensing a p-cyano-benzaldehyde and a p-cyano-benzylcyanide according to the method described by Bell et al., J. Chem. Soc.



  1024 (1948) to obtain a 4,4-tri-cyano-stilbene which is then converted into α-cyano-stilbene-dicarboxylic acid.



   Fibers, sheets, films and other articles made of normally translucent or transparent polymers, and, in particular, of regenerated cellulose, modified or not, of cellulose esters, of polyesters, of polyamides, of polyolefins, of polymers and copolymers of acrylonitrile, polyurethanes, etc., exhibit a distinct yellowish coloration which becomes more pronounced over time. This yellowish color is evident in articles which are neither colored nor dyed, made of these substances. In the case of dyed or colored articles, their clarity is lowered by this yellow coloring and this defect worsens over time.



   It is surprising to note that the compositions based on polymers which contain a compound of formula (I) are superior to the previously known compositions containing a fluorescent brightening agent. Many known compositions which contain a fluorescent brightening agent often exhibit undesirable staining due to the inherent color of this agent or the fact that the fluorescent lux father contains unwanted radiation.



  Other known compositions, which contain a fluorescent brightening agent, are not stable to heat or light or do not withstand washing, dry cleaning, bleaching, textile treatments, etc., and will not resist. gradually color. On the contrary, the compositions containing a compound of formula (I) exhibit a remarkable combination of properties: they exhibit a high clarity and / or a high whiteness of very desirable shade, which are surprisingly resistant to light, to heat, sublimation, friction and the treatment and cleaning operations already indicated. In addition, the presence of these new fluorescent compounds in these compositions has no detrimental effect on the physical properties thereof.



   The remarkable properties of the articles and of the compositions according to the invention do not depend essentially on the mode of incorporation of the fluorescent compound. For example, the incorporation of the compound into the polymers before extruding or spinning gives very good results, as well as the incorporation during the manufacture of the polymer. It is therefore possible to incorporate the stilbenic compounds of formula (I) by immersing the support or the article in an aqueous dispersion of these compounds. The stilbenic compound can also be incorporated, either directly or by means of a masterbatch, into the melt ready to be spun or extruded to form fibers or films or sheets of synthetic resin.



  The fluorescent stilbenic compound can also be mixed with a molding powder in a conventional mixer. In the case of certain polymers which melt at a relatively low temperature, such as polyolefins, a mixture of the polymer and the fluorescent stilbenic compound can be calendared on heated rolls.



   The fluorescent stilbenic compounds of formula (I) can be used to increase the clarity and / or improve the whiteness of any natural or synthetic polymer normally used to prepare fibers, filaments, sheets, films, molded articles. or extrudates, etc., in particular polyolefins, for example polyethylene, polypropylene and polyallomers, polyesters, for example poly (ethylene terephthalate), poly (1,4-cyclohexylenedimethylene terephthalate) and poly - (ethylenenaphthalene dicarboxylate) or varieties of these polyesters which contain other bifunctional compounds, dyeing aids, etc.,

   acrylonitrile polymers and copolymers, polyurethanes, regenerated cellulose, modified or not, cellulose esters, for example cellulose acetate, cellulose triacetate, cellulose acetobutyrate, polyamides, polyester elastomers, etc. .



   The concentration of the fluorescent stilbenic compound can be varied considerably, depending on the color of the undyed base substance and the fluorescence index of the fluorescent stilbenic compound. In general, optimum results are obtained for quantities of fluorescent agent which are between 0.005 part by weight and 0.5 part by weight per 100 parts of the base substance. However, larger or smaller concentrations give satisfactory results and may in some cases be preferable.



   Particularly good results are obtained by the addition of 0.01 to 0.05 part of 4,4'-bis- (benzoxazol-2-yl) -stilbene or of 4,4 '- (6-methylsulfonylbenzo- oxazol-2-yl) -stilbene or 4, 4'-bis- (5-methoxybenzo- oxazol-2-yl) -stilbene to 100 parts of poly- (ethylene terephthalate) or poly- (terephthalate) of 1,4-cyclohexylenedimethylene) or of cellulose acetate or of an article of polypropylene or of polyallomer or of a copolyester of a cyclic dicarboxylic acid, of cyclohexanedimethanol and of copolyether glycol or by the addition of 0, 01 to 0,

   1 part of these same compounds to 100 parts of cellulose acetate butyrate or by the addition of 0.01 to 0.05 part of bis- (benzoxazol-2-yl) -stilbene or of 4, 4'-bis - (6-methylsulfonyl-benzoxazol-2-yl) -stilbene or 4, 4'-mis- (6-chloro-benzoxazol-2-yl) -stilbene or 4, 4'-bis- (5-methoxybenzoxazol- 2-yl) -stilbene to 100 parts of a copolymer of acrylonitrile and vinylidene chloride or by the addition of 0.01 part to 0.05 of 4,4'-bis- (benzooxazol-2- yl) -stilbene or 4, 4'-bis- (6-methylsulfonyl-benzoxazol-2-yl) -stilbene or 4,

     4'-bis- (6-methoxy-benzoxazol-2-yl) -stilbene containing 100 parts of polyethylene.



   The novel compounds of formula (I) are also useful in photographic materials used for color proofing and comprising a white reflective backing which carries three layers of silver halide emulsion which record red, green and. blue. For example, if the silver halide emulsion layer furthest from the support contains a dispersion of an organic solvent in which one of the new compounds is dissolved or dispersed or a mixture of several of these compounds. For example, an oily dispersed phase is incorporated into this emulsion layer in which are dissolved a chromogenic coupler which forms a blue-green dye and one or more of the new compounds according to the invention.

   One or more of the new compounds can also be dissolved in a separate oily phase which is dispersed in this layer.



   Fluorescence of compounds of formula (I) provides color photographic prints with improved whiteness in low optical density ranges. In addition, thanks to the absorption in the ultraviolet specific to these new compounds, the magenta and yellow images formed in the emulsion layers arranged under the layer of the blue-green image are protected.

   As the usual blue-green dyes which are formed by chromogenic development absorb ultraviolet, the new compounds of formula (I) do not emit fluorescence in the areas of the blue-green image. this avoids the undesirable optical effect which occurs when optical brighteners are overcoated on the color proofs or when they are introduced by immersion.



   The new fluorescent compounds of formula (I) absorb in the ultraviolet and exhibit a maximum absorption at a wavelength of between 350 mut and 390 mol. They have a molecular absorption coefficient of between 47,000 and 94,000 for the wavelength which corresponds to the maximum absorption in the ultraviolet. In solution or on a support, these new compounds emit fluorescence light, the wavelength corresponding to the maximum emission of which is between 420 mu and 450 mu; in daylight or in the ultraviolet, this fluorescence therefore appears blue green to purple.

   The 4, 4'-bis- (benzoxazol-2-yl) -stilbenes which we prefer to use do not introduce any apparent coloration, or introduce little of it, when they are incorporated into a polyester product in sufficient quantity. to improve whiteness or enhance clarity and, therefore, should not bear substituents which would introduce such coloring under these conditions.



   In addition, the compounds of formula (I) which it is preferred to use exhibit satisfactory stability. When incorporated into a polyester product in an amount sufficient to improve whiteness or enhance clarity, they impart exceptional whiteness or clarity to the product which resists the appearance of any unwanted coloration, is lightfast or lightfast. to air and to washing and bleaching agents, such as sodium hydrochlorite and calcium hypochlorite.



   The preferred 4,4'-bis- (benzoxazol-2-yl) -stilbenes of formula (I) have a fluorescence index of at least 3.40. The fluorescence index is a measure of the relative luminance of stilbenes. fluorescent agents used as brightening or optical brightening agents. A compound of satisfactory fluorescence index is not necessarily suitable as an optical brightener or brightener, as it may be unstable or have an excessively intense inherent coloration.



   There is a relationship between the absorption of light by fluorescent compounds and the emission of fluorescence. Theoretically, each quantum of light absorbed should correspond to the emission of a quantum, in which case the fluorescence yield would be equal to unity. However, the energy of the light emitted by fluorescent compounds is less and corresponds to wavelengths greater than those of the light absorbed. A fraction of the energy is lost in the form of heat.



   It is possible to specify the nature of the light absorbed by means of the molecular extinction coefficient which is the product of the absorption factor in the ultraviolet by the molecular mass of the compound. For 4, 4'-bis- (benzoxazol-2-yl) -stilbene, this coefficient is 79,488. Here is calculated from observations made at the wavelength of 373 mg which corresponds to the maximum absorption in the ultraviolet. The molecular extinction coefficients of the new fluorescent compounds of formula (I) are between 47,000 and 94,000 and the absorption maxima in the ultraviolet correspond to wavelengths between 350 mst and 390 mst.



   Using suitable laboratory instruments, the quantitative characteristics of the light emitted by fluorescent compounds, namely the wavelength of maximum emission and the fluorescence index, can be determined. For 4, 4'-bis (benzoxazol-2-yl) -stilbene, these characteristics are 432 mlt and 4, 99 respectively. In general, the maximum emission of the compounds of formula (I) corresponds to a wavelength of between approximately 420 mst and 450 mlt.



   From the above, it is deduced that it is desirable that the fluorescence index be as high as possible without, however, undesirable coloration appearing in the polyester product. The higher the fluorescence index, the lower the concentration of a given compound which is required to achieve a given value of luminance in the product. Fluorescent 4,4'-bis- (benzoxazol-2-yl) -stilbenes with a fluorescence index of at least 3.40 are particularly useful as brighteners and optical brighteners, although they can be used. use as such certain compounds whose fluorescence index is lower.



   The fluorescence index (R) is given by the expression
 FO, 12] [2]
 Vs X Cs where FA is the relative fluorescence intensity measured by a 931-A photomultiplier detector calibrated using 2ml of an aqueous solution of quinone sulfate at a concentration of 20Ftg / ml, Vs the volume of the sample in milliliters and Cs the concentration in micrograms per milliliter.



   For example, the FA value in the apparatus used is 10.00 per 2 ml of an aqueous solution of quinine sulfate containing 20 µg of quinine sulfate per milliliter. If the sample is dissolved in an organic solvent at a concentration of 0.12 stg / milliliter and a total volume of 2 ml of this solution is used in the apparatus, a range of values is available to compare the values. fluorescence properties of a large number of new compounds.

   This technique makes it possible to measure the fluorescence index for compounds whose fluorescence yield is greater than that of the standard consisting of quinine sulfate and whose luminance is greater than that of quinine sulfate at the concentration of 20g / ml. For example, a fluorescence index of 4.0 means that the luminance of this compound is 40/100 of that of quinine sulfate under the above conditions.



   The hydrogen atoms or other substituents attached to the carbon atoms of the ethylene bond of the stilbene group present in the new compounds of formula (I) can be arranged according to the cis or trans configuration or simultaneously according to these two configurations.



   The following examples show how the stilbenic compounds of formula (I) can be prepared.



   Example 1
 4, 4'-bis- (benzoxazol-2-yl) -stilbene
 4,4'-Stilbene-dicarboxylic acid is prepared from p-toluic acid by the method described in J. Amer. Chem. Soc. 75, 2263 (1953). 4,4'-Stilbene-dicarboxylic acid chloride is prepared from the acid according to the method described in
J. Amer. Chem. Soc. 68, 2167 (1946).



   4,4'-Bis- (2-hydroxy-phenylcarba-moyl) -stilbene is prepared by dissolving 1.5 g of 4,4'-stilbene-dicarboxylic acid chloride in 50 ml of hot dioxane and adding to this solution of 1.1 g of o-amino-phenol dissolved in 5 ml of dioxane. A precipitate is immediately deposited. Heat at reflux for two hours for the reaction to be complete, cool and collect 1.8 g of a brown precipitate which decomposes at 3000-3200 C.

   This brown precipitate, which is 4,4'-bis- (2-hydro-oxy-phenylcarbamoyl) -stilbene, is heated in vacuo on an oil bath at 320oxo C until the reaction ceases.



  The product is cooled in vacuo and extraction with benzene is carried out in a Soxhlet apparatus.



  4, 4'-bis- (benzoxazol-2-yl) -stilbene (0, 93g), F: 365 - 3680C, crystallizes in the benzene solution in the form of bright yellow flakes. The elementary analysis gives the following results:
 Calculated for C28Hj8N202:
 C 81, 2 H 4, 35 N 6, 77
 Found: C 81, 3 H 4, 60 N 6, 65
 Example 2
 4,4'-di- (benzoxazol-2-yl) -2-methyl-stilb¯ne
 2-methyl-4, 4'stilb¯ne-dicarboxylic acid chloride is prepared from the corresponding acid using the method described in J. Amer.



  Chem. Soc. 68, 2167 (1946). The acid is obtained by hydrolysis of dinitrile as described in J. Amer
Chem. Soc. 68, 2167 (1946) and the dinitrile is prepared according to the technique described in J. Chem. Soc. 690 (1947).



   3.2 g (0.01 mole) of 2-methyl-4, 4'-stilbene-dicarboxylic acid chloride are dissolved in 100 ml of hot dioxane and 2.2 (0.2 mole) are added oamino-phenol in 10 ml of dioxane. A precipitate is deposited immediately. The mixture is refluxed for two hours for the reaction to be complete and the precipitate is collected after cooling. There is thus obtained 3.7 g of a light brown solid which is 4,4'-di- (2-hydroxy-phenylcarbamoyl) -2-methyl-stilbene.



   This product (3, 7g) is heated in vacuo on an oil bath at 320 "-340" C until the reaction ceases. The product is cooled in vacuo and extraction with benzene is carried out in a Soxhlet apparatus. The benzene solution leaves behind 2.0 g of yellow flakes of 4,4'-di- (benzoxazol-2-yl) 2-methyl-stilbene.



   Example 3 4, 4'-di- (benzoxazol-2-yl) -a-cyano-stilbene
 The α-cyano-stilbene-dicarboxylic acid chloride is prepared from the corresponding acid, according to the method described in J. Amer. Chem. Soc. 68, 2167 (1946). The acid is obtained by partial hydrolysis of 4, 4'-a.-tricyano-stilbene with sulfuric acid in acetic acid at 140 ° C., J. Chem. Soc. 1024 (1948). The latter is obtained by condensation of pcyano-benzaldehyde with p-cyano-benzylic cyanide as described in J. Chem. Soc. 1024 (1948).



   3.3 g of α-cyano-stilbene-dicarboxylic acid chloride are dissolved in 100 ml of hot dioxane and 2.2 g (0.02 mole) of o-amino-phenol in 10 ml are added. of dioxane. An intermediate precipitate forms immediately. The mixture is refluxed for two hours so that the reaction is complete and the precipitate finally obtained is collected after cooling. There is thus obtained 3.32 g (700/0) of 4, 4'-di- (2-hydroxy-phenylcarbamoyl) - a-cyano-stilbene in the form of a pale brown solid.



   The latter compound (3.32 g) is heated under vacuum on an oil bath at 3200-3400 C until the reaction ceases. The mixture is cooled under vacuum and extraction with benzene is carried out in an apparatus.
Soxhlet. The benzene solution deposits 1.84 g (60 / o) of yellow flakes of 4,4'-di- (benzoxazol-2-yl) -a-cyano stilbene.



   Example 4
 4, 4'-d- (benzoxazol-2-yl) -2ss2'-di? tet / 7yl-stilbene
 2,2'-Dimethyl-4, 4'-stilbene-dicarboxylic acid chloride is prepared by reaction of the corresponding acid with thionyl chloride and phosphorus pentachloride. The acid is obtained by hydrolysis of the dinitrile with a 10/100 solution of potassium hydroxide in propylene glycol, as described in J. Amer. Chem. Soc. 68, 2167 (1946).

   The dinitrile is obtained by reacting cuprous cyanide with &alpha; -carboxy-4, 4'-dibromo-2, 2'-dimethyl-stilbene, which is itself obtained by condensation of 4-bromo-2-methyl-phenylacetate. potassium with 4-bromo-2 methyl-benzaldehyde and acetic anhydride in the presence of pyridine, as described in J. Chem. Soc.



  690 (1947).



   3.3 g (0.01 mole) of 2, 2'-dimethyl-4, 4'-stilbene-dicarboxylic acid chloride is dissolved in 100 ml of hot dioxane and 2.2g (0.2g (0, 02 mol) of o-amino-phenol in 10 ml of dioxane. After formation of the intermediate precipitate, the mixture is heated at reflux for two hours to complete the reaction, cooled and the precipitate collected. 3.1 g (65/0) of pale brown sheets are obtained consisting of 4, 4'-di- (2 "-hydroxy-phenylcarbamoyl) -2, 2'-dimethyl-st: lbene. empty, on an oil bath at 3200-3400 C until the reaction ceases.

   The product is cooled in vacuo and extraction with benzene is carried out in a Soxhlet apparatus. The benzene solution forms yellow sheets of 4, 4'-di- (benzoxazol-2-yl) -2, 2'-dimethyl-stilbene (2.75 g).



   Example S 4, 4'-di- (6 snethoxy-benzoxazol-2-yl) -stilbene
 3, 0 g of the 4, 4'-stilbene-dicarboxyl acid chloride, prepared as indicated in Example 3, are dissolved in 100 ml of hot dioxane, and a solution of 2, 78 g of 2- amino-5-methoxy-phenol (Ber; 46, 3382) in 10 ml of dioxane. After formation of the intermediate precipitate, the mixture is kept at reflux for two hours for the reaction to be complete, cooled and the precipitate is collected. 3.7 g (75 O / o) of 4,4'-di- (2-hydroxy-4-methoxy-phenylcarbamoyl) -stilbene are obtained.



   The latter (3.7 g) is heated under vacuum on an oil bath at 3200-3400 C, until the reaction ceases. The product is cooled in vacuo and extraction with benzene is carried out in a Soxhlet apparatus. Yellow flakes of 4, 4'-di- (6-metoxy-benzoxazol-2-yl) -stilbene crystallize from the benzene solution (2.28 g).



     Fxels7ple 6
 4,4'-di- (benzoxazol-2-yl) -2-nitro-stilb¯ne
 2-Nitro-4, 4'-stilbene-dicarbonyl chloride is prepared from the corresponding acid and dinitrile, according to the method described in J. Amer.



  Chem. Soc. 68, 2167 (1946). The dinitrile is obtained by condensation of 4-methyl-3-nitro-benzonitrile and 4-cyano-benzaldehyde, as decreed in United States Patent No. 2510047.



   3.5 g of 2-nitro-4, 4'-stilb¯ne dicarbonyl chloride are dissolved in 100 ml of hot dioxane and a solution of 2.2 g of o-amino-phenol in 10 ml of dioxane is added. After maintaining the reflux temperature for two hours for the reaction to be complete, the mixture is cooled and the precipitate is collected. tee consisting of 3.0 g of 4, 4'-di- (2 hydroxy-phenylcarbamoyl) -2-nitro-stilbene of yellow color. The latter is heated in vacuo on an oil bath Ó 320¯-340¯ C until the reaction ceases.



  The product is cooled in vacuo and extraction is carried out with benzene in a Soxhlet apparatus. 2.1 g of yellow sheets of 4.4 '(di-benzoxazol-2-yl) -2-nitro-stilbene are obtained.



   Exerrtple 7
 4, 4'-di- (benzoxazol-2-yl) -2-amino-stilb¯ne
 2.1 g of 4,4'-di- (benzoxazol-2-yl) -2 nitro-stilbene, prepared as described in Example 6, are reduced by treating it with stannous chloride in concentrated hydrochloric acid. By operating as is usual for this type of reduction, 1.2 g of yellow platelets of 4, 4'-di- (benzoxazol-2-yl) -2-amino-stilbene are obtained.



   Example 8
 4, 4'-di- (benzoxazol-2-yl) -2-A1ydroxy-stilbene
 1.2 g of 4, 4'-di- (benzoxazol-2-yl) -2-amino-stilbene, prepared as described in Example 7, are dissolved in 17 ml of acetic acid and 3 ml of propionic acid and diazotization is carried out at 0 - 5 "C by dropwise addition and stirring of an equivalent of nitrosylsulfuric acid in 5 ml of sulfuric acid and 10 ml of the mixture of acetic acid and ac of When the diazotization is complete, the reaction mixture is poured into 100 ml of water and brought to the boil.

   On cooling, 0.96 g of a yellow precipitate of 4,4'-di (benzoxazol-2-yl) -2-hydroxy-stilbene is obtained.



     Fxesllple 9
 4,4'-di- (benzoxazol-2-yl) -2-chloro-stilb¯ne
 As described in Example 8, a solution of 6.0 g of 4,4'-di- (benzoxazol-2-yl) -2-amino-stilbene diazotÚ is prepared and this solution is poured into a solution of 3 g of cuprous chloride freshly precipitated in 10 ml of concentrated hydrochloric acid and 15 ml of water. The reaction mixture was brought to the boil, then cooled to obtain 4.4 g of a yellow precipitate of 4,4'-di- (benzoxazol-2-yl) -2-chloro-stilbene.



   Exeotiple 10
 4, 4'-di- (benz, oxazol-2-yl) -2-cyano-stilbene
 Carefully neutralized with sodium carbonate at 0-50 C, a solution of 4, 4'-di- (benzoxa zol-2-yl) -2-amino-stilbene diazotized (6.0 g) prepared as it is. described in Example 8.



   This neutralized diazonium solution is added slowly and with stirring to a suspension of 5 g of cuprous cyanide freshly precipitated in 20 ml of water and 20 ml of benzene (Orgaric Syntheses, Coll.



  Flight. 1, page 514). Nitrogen is evolved and the product which precipitates is partially taken up in benzene.



  The precipitate and the benzene layer are combined and heated. On cooling, the benzene solution gives 3.8 g of yellow sheets of 4, 4'-di (benzoxazol-2-yl) -2-cyano-stilbene.



   Example 11
 4, 4'-bis- (6-chloro-benzoxazol-2-yl) -stilbene
 This compound is prepared by applying the procedure of Example 1 where o-amino-phenol is replaced in the third step of the synthesis by an equimolecular amount of 2-amino-5-chlorophenol.



   Example 12
 4, 5'-bis- (6-methylsulphonyl-benzoxazol-2-yl) -stilbene
 This compound is prepared by following the procedure described in Example 1 and replacing the o-amino-phenol in the third step of the synthesis with an equimolecular amount of 2-amino-5-methyl-sulfonyl-phenol.



   Example 13
 4, '-bis- (5-cyano-benzoxazola2-yl) -stilbene
 This compound is prepared by following the procedure of Example 1 and replacing o-amino-phenol in the third step of the synthesis with an equimolecular amount of 2-amino-4-cyano-phenol.



   The following Este lists other fluorescent brightening agents which can be prepared by following the procedures given in the previous examples:
 1,4,4'-bis- (6-acetyl-benzoxazol-2-yl) -stilbene
 2. 4, 4'-bis- (6-trifluoromethyl-benzoxazol-2-yl) -
 stilbene
 3,4-bis- (6-carbÚthoxy-benzoxazol-2-yl)
 stilbene
 4.44'-bis- (6-phÚnoxy-benzoxazol-2-yl) -stilb¯ne
 5.4,4'-bis- (6-dimethylsulfamyl-benzoxazol-2-yl)
 stilbene
 6.4,4'-bis- (6-dimethylcarbamyl-benzoxazol-2-yl) -
 stilbene
 7.4,4'-bis- (6-thiocyano-benzoxazol-2-yl) -stilb¯ne
EMI7.1


<tb> <SEP> COOCH3
<tb> 8. <SEP> 4, <SEP> 4 '- (6-N-benzoxazol-2-yl) -stilbene
<tb> <SEP> CHs
<tb>
 9.44'-bis- (6-chloro-benzoxazol-2-yl) -stilbene 10.

   4, 4'-bis- (6-bromo-benzoxazol-2-yl) -st. lbene 11.4, 4'-bis- (benzoxazol-2-yl) -2-methylsulfonyl-
 stilbene 12.4, 4'-bis- (benzoxazol-2-yl) -2-dimethylsulfamyl-
 stilbene 13. 4, 4'-bis- (benzoxazol-2-yl) -2-acÚtyl-stilb¯ne 14. 4, 4'-bis- (benzoxazol-2-yl) -2-thiocyano-stilbene 15. 4 , 4'-bis- (benzoxazol-2-yl) -2-trifluoromethyl stilbene 16. 4, 4'-bis- (benzoxazol-2-yl) -2-carbomethoxy-
 stilbene
EMI8.1


<tb> <SEP> / COOCH3
<tb> 17. <SEP> 4, <SEP> 4 "-bis- <SEP> (benzoxazol-2-yl) -2-N-stil
<tb> <SEP> bene <SEP> CH3
<tb>
 18. 4, 4'-bis- (6-methoxy-benzoxazol-2-yl) -a, ss-di-ethyl-stilbene
 19.

   4, 4'-bis- (6-chloro-benzoxazol-2-yl) - &alpha;, ¯-diÚthyl-
 stilbene 20. 4, 4'- (6-ethylsulfonyl-benzoxazol-2-yl) -a, p-di-ethyl-stilbene 21. 4, 4'-bis- (6-dimethylsulfamyl-benzoxazol-2-yl) a , p-diethyl-stilbene 22. 4, 4'-bis- (6-dimethylcarbamyl-benzoxazol-2-yl) -
 a, p-diethyl-stilbene 23. 4, 4'-bis- (6-trifluoromethyl-benzoxazol-2-yl) -
 a, p-diethyl-stilbene 24. 4, 4'-bis- (6-difluoromethyl-benzoxazol-2-yl) -
 a, ¯-diÚthyl-stilb¯ne 25. 4, 4'-bis- (6-bromo-benzoxazol-2-yl) -a, p-diethyl-
 stilbene 26.

   4, 4'-bis- (5-methoxy-benzoxazol-2-yl) -a, p-di-ethyl-stilbene 27. 4, 4'-bis- (5-chloro-benzoxazol-2-yl) -a , p-diethyl
 stilbene 28. 4, 4'-bis- (5-thiomÚthyl-benzoxazol-2-yl) - &alpha;, ¯-di-ethyl-stilbene 29. 4, 4'-bis- (5-Úthylsulfonyl-benzoxazol-2- yl) - &alpha;, ¯- diethyl-stilbene 30. 4, 4'-bis- (5-dimethylsulfamyl-benzoxazol-2-yl) -
   a, ¯-diÚthyl-stilb¯ne 31. 4, 4'-bis- (5-dimÚthylcarbamyl-benzoxazol-2-yl) &alpha;

  , ¯-diÚthyl-stilb¯ne 32. 4, 4'-bis- (5-carbethoxy-benzoxazol-2-yl) -a, p-di-ethyl-stilbene 33. 4, 4'-bis- (5- trifluoromethyl-benzoxazol-2-yl) - &alpha;, ¯-diÚthyl-stilb¯ne 34. 4, 4'-bis- (5-hydroxy-benzoxazol-2-yl) -a, p-di-ethyl-stilbene 35 . 4, 4'-bis- (5-acÚtamido-benzoxazol-2-yl) - &alpha;

  , ¯-Di-ethyl-stilbene 36. 4, 4 '- (6-methoxy-benzoxazol-2-yl) -2-chloro-
 stilbene 37. 4, 4'-bis- (6-dimÚthylcarbamyl-benzoxazol-2-yl)
 2-chloro-stilbene 38. 4, 4'-bis- (6-aedtamido-benzoxazol-2-yl) -2- chloro-stilbene 39. 4, 4'-bis- (6-phenoxy-benzoxazol-2-yl ) -2-chloro-
 stilbene 40. 4, 4'-bis- (6-bromo-benzoxazol-2-yl) -2-chloro-
 stilbene 41. 4, 4'-bis- (6-cyano-benzoxazol-2-yl) -2-chloro-
 stilbene 42. 4, 4'-bis- (6-acetyl-benzoxazol-2-yl) -2-chloro-stilbene 43. 4, 4'-bis- (6-methoxy-benzoxazol-2-yl) -2- In this-
 amido-stilb¯ne 44. 4, 4'-bis- (6-acÚtamido-benzoxazol-2-yl) -2-acÚt
 amido-stilbene 45.

   4, 4'-bis- (6-cyano-benzoxazol-2-yl) -2-acetamido-
 stilbene 46. 4, 4'-bis- (6-thiocyano-benzoxazol-2-yl) -2-acet-
 amido-stilbene 47. 4, 4'-bis- (6-methyl-benzoxazol-2-yl) -2-acet-
 amido-stilb¯ne 48. 4, 4'-bis- (6-dimethylsulfamyl-benzoxazol-2-yl) - methyl-stilbene 49. 4, 4'-bis- (6-mÚthoxy-benzoxazol-2-yl) - 2, 2'-di methyl-stilbene 50. 4, 4'-bis- (6-Úthoxy-benzoxazol-2-yl) -2, 2'-di methyl-stilbene 51. 4, 4'-bs- (6 -dimethylsulfamyl-benzoxazol-2-yl) -
 2, 2'-dimÚthyl-stilb¯ne 52. 4, 4'-bis- (6-thiomethyl-benzoxazol-2-yl) -2, 2'-di-
 methyl-stilbene 53.

   4, 4'-bis- (6-cyano-benzoxazol-2-yl) -2, 2'-di methyl-stilbene 54. 4, 4'-bis- (6-acetamido-benzoxazol-2-yl) -2 , 2'-Di-methyl-stilbene 55. 4, 4'-bis- (5-chloro-benzoxazol-2-yl) -2-chloro-stilbene 56. 4, 4'-bis- (5-mÚthoxy-benzoxazol -2-yl) -2-methyl
 stilbene 57. 4, 4'-bis- (5-bromo-benzoxazol-2-yl) -2-methyl
 stilbene 58. 4, 4'-bis- (5-thiomÚthyl-benzoxazol-2-yl) -2-mÚ thyl-stilbene 59. 4, 4'-bis- (5-dimÚthylsulfamyl-benzoxazol-2-yl) 2- methyl-stilbene 60. 4, 4'- (5-trifluoromethyl-benzoxazol-2-yl) -2 methyl-stilbene 61. 4, 4'-bis- (5-iodo-benzoxazol-2-yl) -2-mÚthyl stilbene 62.

   4, 4'-bis- (5-mÚthyoxy-benzoxazol-2-yl) -2-cyano
 stilbene 63. 4, 4'-bis- (5-methyl-benzoxazol-2-yl) -2-cyano
 stilbene 64. 4, 4'-bis- (5-p-methoxy-phenyl-benzoxazol-2-yl) 2-cyano-stilbene 65. 4, 4'-bis- (5-trifluoromethyl-benzoxazol-2-yl) -2
 cyano-stilbene 66. 4, 4'-bis- (5-carbomÚthoxy-benzoxazol-2-yl) -2
 cyano-stilbene 67. 4, 4-bis- (5-acÚtamido-benzoxazol-2-yl) -2-cyano
 stilbene 68. 4, 4'-bis- (5-cyano-benzoxazol-2-yl) -2-cyano-
 stilbene 69. 4, 4'-bis- (6-ethoxy-benzoxazol-2-yl) -a-cyano
 stilbene 70. 4, 4'-bis- (6-phenoxy-benzoxazol-2-yl) -a-cyano-stilbene 71. 4, 4'-bis- (6- [p-methoxy-phenoxy] -benzoxazol-2 - yl) -α-cyano-stilbene 72.

   4, 4'-bis- (6-carbomethoxy-benzoxazol-2-yl) -a-
 cyano-stilbene 73. 4, 4'-bis- (6-methoxy-benzoxazol-2-yl) -a-cyano-
 stilbene 74. 4,4'-bis- (5-ethoxy-benzoxazol-2-yl) -a-cyano-2-methyl-3'-chloro-stilbene 75.

   4, 4'-bis- (6-methoxy-benzoxazol-2-yl) -a-cyano
 2-methyl-3'-chloro-stilbene
 For the sake of clarity, it should be indicated that the term dimethylsulfamyl denotes the N, N-dimethylsulfamyl group of formula SO2 (CH.)). Likewise, the term dimethylcarbamyl denotes the N, N-dimethylcarbamyl group of formula CON (CHS) 2. The terms sulfamyl and carbamyl used in this specification are synonymous with the terms sulfamoyl and carbamoyl, as indicated in Chemical.
Abstracts, vol. 56 (January to June 1962), p. 87N-91N.



   The numbering used in this specification for the benzoxazole ring is that given in The Ring Index, Patterson, Capell and Walker, Second Edition (1960), American Chemical Society. By way of example, compound 74 of the preceding list corresponds to the formula
EMI9.1

 The following examples illustrate the invention:
 Example I
 A poly- (ethylene terephthalate) composition containing 4,4'-bis- (benzoxazol-2-yl) - stilbene is prepared by adding 0.40 parts by weight of the stilbenic compound to 100 parts by weight of the mixture. polyester powder and 7.0 parts by weight of titanium oxide to form a masterbatch.

   The master mixture is melted and shaped by extruding rods which are cut into beads. The pearls of the masterbatch are then mixed with poly (ethylene terephthalate) pearls in the ratio of 1 part by weight of the first to 19 parts by weight of the seconds. The bead mixture is melted and the molten composition is extruded through a die to form a white poly (ethylene terephthalate) fiber containing about 0.02 parts by weight of the stilbenic compound per 100 parts by weight of fiber. The fiber thus obtained exhibits improved whiteness in daylight and blue fluorescence in the ultraviolet.



   Example 11
 0.010 part by weight of 4, 4'bis- (benzoxazol-2-yl) -stilbene and 100 parts by weight of granules of poly- (1,4-cyclohexylene dimethylene terephthalate) containing 0.35 are dry mixed. part by weight of titanium oxide per 100 parts of polyester. By melting the mixture and extruding through a die, a white fiber of poly- (1,4 cyclohexylenedimethylene terephthalate) is obtained containing about 0.010 part by weight of 4,4'-bis- (benzoxazol-2-yl) -stilbene per 100 parts of fiber and exhibiting improved whiteness when observed in daylight and blue fluorescence when observed in ultraviolet.



   The fibers of Examples I and II show improved whiteness when viewed in daylight. The colorimetric properties of these fibers are not modified by the textile treatments, nor essentially by an exposure of 60 h in the Fade-Ometer apparatus. They are also stable to gas, sweat, sublimation, friction, washing and dry cleaning, as shown by tests according to the procedures given in the 1962 edition of the Technical Manual of the American Association of Textile Chemists and
Colorists.



   The white polyester fiber prepared as described in Example II is woven and 100 parts by weight of the resulting fabric are dyed with 0.088 parts by weight of 4- (4-p-hydroxyethylanIIne) -5-nitro-1. , 8-dihydroxyhydroquinone mixed with sodium ligninsulphonate and the product <Igepon T 48, 3 (1959). The obtained blue fabric is of greater clarity than that of a fabric dyed under the same conditions, but made of poly- (1,4-cyclohexylenedimethylene terephthalate) fibers containing no fluorescent compound. The color fastness properties are identical for both fabrics.



   Ild example
 Polyethylene articles are prepared by dry mixing 100 parts by weight of polyethylene and 0.02 parts by weight of 4,4'-bis- (6-methylsulfonyl-benzoxazol-2-yl) -stilbene and molding the product. mixed by injection at 180 C. The polyethylene articles obtained exhibit an intense blue fluorescence when exposed to ultraviolet light, which improves the apparent whiteness when viewed in daylight. This enhanced whiteness is very stable to light and heat.



   Example IV
 0.02 part by weight of 4,4'-bis (benzoxazol-2-yl) -stilbene and 100 parts by weight of a copolyester of terephthalic acid, 1,4-cyclohexane-dimethanol and poly- are mixed. (tetramethylene glycol). By melt spinning, an elastomeric polyester fiber is obtained, the whiteness of which is improved and exhibits good strength properties.



   Example V
 0.58 parts by weight of Watchung Rouge and 0.0058 parts by weight of 4,4'-bis- (6-methylsulfonylbenzoxazol-2-yl) -stilbene are mixed in a mill with 100 parts of a ketone solution. 29 / o of cellulose acetate and this solution is spun. Red fibers are obtained of considerably greater clarity than that of red fibers of the same nature not containing the stilbenic compound.



   Example VI
 A sheet of cellulose acetate butyrate is prepared by calendering a mixture of 0.1 part of 4, 4'-bis- (benzoxazol-2-yl) -stilbene, 100 parts of cellulose acetate butyrate and 5 parts dioctyl phthalate on cylinders heated to 1200 ° C. and the plastic mass obtained is pressed between metal plates maintained at the same temperature.



  The sheet obtained exhibits an intense and permanent blue fluorescence.



   Example Vll
 0.02 part by weight of 4,4'-bis- (6-chlorobenzoxazol-2-yl) -stilbene is incorporated into a solution containing 18 parts of poly-N-isopropylacrylamide and 82 parts. es of a copolymer of acrylonitrile and vinylidene chloride and the mixture is spun. The fiber obtained exhibits improved fluorescence properties and very good strength.



   Example Vlll
 Before spinning, 0.02 part by weight of 4, 4'-bis- (benzoxazol-2-yl) -stilb6ne is incorporated into 100 parts by weight of cellulose acetate or of cellulose triacetate or of polyacrylonitrile or of polyester elasto - mother Lyora (manufactured by Du Pont de Nemours) or polyurethane elastomer Vyrene (manufactured by
U. S. Rubber Company). By spinning, fibers are obtained whose whiteness is improved and has very good strength properties.



      Example IX
 Results analogous to those of Example VIII are obtained with the same fibers by replacing 4, 4'-bis- (benzoxazol-2-yl) -stilbene by an equal amount of 4,4'-bis- ( 6-methylsulfonylbenzoxazol-2-yl) - stilbene.



   Example X
 0.02 part by weight of 4, 4'-bis (benzoxazol-2-yl) -stilbene is incorporated into 100 parts of polymer consisting of polypropylene, or polyethylene, or a polyallomer, and a sheet is formed by proceeding as indicated in Example VI. In each case, the sheet obtained exhibits a permanent blue fluorescence.



   Example XI
 Results similar to those of Example VI are obtained by operating as indicated in this example and replacing 4, 4'-bis- (benzoxazol-2-yl) -stilbene by the same quantity of 4, 4 ' -bis- (6-methylsulfonylbenzoxazol-2-yl) -stilbene. This fluorescent compound can be incorporated in the same way in a sheet of cellulose acetate butyrate and also obtain a permanent blue fluorescence.



      Example Xll
 In a 250 ml flask are introduced 29.1 g (0.15 mol) of dimethyl terephthalate, 41 g (0, 20 mol) of a 70/100 methanolic solution of 1.4cyclohexanedimethanol (68/100 of trans isomer), 0, 0082g of 4, 4'-bis- (benzoxazol-2-yl) -stilbene, 0, 0441 gram of Monastral Blue B and 0, 4 ml of a 21/100 solution of double butyrate of magnesium and titanium in n-butanol. The mixture is heated under nitrogen to 2000-2100 C, with stirring. When the alcoholysis is complete, the temperature is raised to 305 ° C. and the vacuum is applied as quickly as possible.

   Stir in vacuo at this temperature for 45 minutes, then the clear viscous product is cooled to room temperature, while maintaining a vacuum. The polymer finally obtained is in the form of a very clear white opaque mass, of intrinsic viscosity of 0, 99. Analysis by fluorescence of the polymer indicates that it contains 0, 018 parts by weight of the stilbenic compound per 100. polymer parts.



  By spinning in the molten state, fibers are obtained whose very high whiteness has a stability hitherto unknown. Likewise, the clarity of films obtained by melt extrusion is very high and permanent, and these films exhibit permanent blue fluorescence when viewed in the ultraviolet.


 

Claims (1)

CLAIM Use of stilbenic compounds of formula: EMI10.1 in which R represents a rad. substituted or unsubstituted cal 4, 4'-stilbene and R 'hydrogen atoms or identical or different substituents, to make objects or articles fluorescent, characterized by the incorporation of these compounds in the objects or articles or their application on objects or articles. SUB-CLAIMS 1. Use according to claim of stilben c compounds of formula above in which the radical R is of formula EMI11.1 in which Y and Y ′ each represent a hydrogen atom or an alkyl, aryl, or cyano group, and in which R "represents one or more substituents taken from halogen atoms, alkyl, aryl, alkylaryl, arylalkyl groups , alkoxy, aryloxy, acyl, acyloxy, hydroxyl, amino, substituted amino, quaternized ammonium, sulfo, substituted sulfonyl, sulfamyl, substituted sulfamyl, cyano, thiocyano, carbamyl, substituted carbamyl, carbamyloxy and nitro. 2. Use according to claim 4, 4'-di- (5 methoxy-benzoxazol-2-yl) -stilbene. 3. Use according to claim 4, 4'-di- (6-methylsulfonyl-benzoxazol-2-yl) -stilbene. 4. Use according to claim 4, 4'-di- (6-chloro-benzoxazol-2-yl) -stilbene. 5. Use according to claim 4, 4'-di- (5-cyano-benzoxazol-2-yl) -stilbene. 6. Use according to claim, in which the object or article is made of a polymer, characterized in that the stilbenic compound is present in an amount of between 0.005 O / o and 0.5 O / o by weight in the polymer. . 7. Use according to sub-claim 6, characterized in that the polymer is a polyester, such as poly- (ethylene terephthalate) or poly- (1,4-cyclohexylened terephthalate: methylene), an acrylonitrile polymer or copolymer, a cellulose ester such as cellulose acetate or cellulose acetate butyrate, a polyolefin such as polyethylene, polypropylene or a polyallomer or a polyamide.