Novel Fluorescent Pigment Compositions and A Process for Their Preparation and Use of Same

?echnical Field

The present invention relates generally to novel fluorescent pigment composition and a process for their synthesis.

The synthesis of novel epoxy sulfonamide resins (para-, meta- or ortho-) . also a part of the present invention, may be incorporated with other reactants to confer added heat resistance and light fastness. These resins act as carriers for the fluorescent dyes which may be incorporated at various stages of the reaction. Newly commercialized aliphatic isocyanates. such as me a- and para-tetramethy1 xyiene diisocyanates ( -T XDI and p-TMXDI , commercially ^" a\*ailable from the American Cyanamid Company, U.S.A.) and an aromatic isocyanate containing the sulfonyl group (e.g., para-toluene sulfonyl isocyanate, available form the Upjohn Company, U.S.A.) are incorporated into the compositions of the invention.

Using the above resins of the present invention, two types of foams, which are easily pulverizable, are produced using various isocyanates as one of the components:

1. The conventional type of urethane foam, by the addition of an appropriate catalyst and a reactive blowing agent, such as, for example, water (which produces carbon dioxide blown foam) or other commonly used foaming agents, such as fluorinated or chlorinated halocarbons, etc.

2. When the novel types of resins of the invention are prepolymers containing isocyanate groups, by the use of a trimerization catalyst, such as DMP-30 (2, ,6-tris(dimethyl amino ethyl phenol), available from the Rohm & Hass Company, Philadelphia, Pennsylvania, U.S.A., and a blowing agent, easily pulverizable heat resistant isocyanurate foams are obtained. The fluorescent dyes are included as part of the composition before the trimerization process.

In addition to the common blowing agents used in the production of urethane foams immediately described above, it has been surprisingly discovered that propylene oxide

( CK -CH _Λ -CH„ )

3 . _: , _: \ /

0 acts as both a solvent and as a blowing agent in the preparation of such foams. The propylene oxide, after expanding the mass by behaving as a blowing agent, enters into the reaction forming the foam.

Background Art

Many flowers have beautiful colors and draw attention at dawn and dusk by exhibiting the phenomenon known as daylight fluorescence. When the possibility of producing synthetic daylight fluorescent pigments was discovered, such pigments were considered the "dream pigments" of the future. (A. V. Lagario, Anqew. Chem. 34, 586 (1921)).

Improving on Widmer's idea of using a resin as a carrier for a dye (see, U.S. Patent 2,119,189, issued to G. Widmer) , Switzer prepared daylight fluorescent pigments with better light fastness and weather resistance from infusible urea and melamine resin (U.S. Patent No. 2,498,592, Switzer e . al . , issued 1950).

The earliest thermoplastic fluorescent pigments based on modified sulfonamide resins, being extremely

friable organic glasses, were able to be ground to a fine particle size. In contrast, the infusable urea and melamine resins were very difficult to grind. (Canadian Patent No. 562,729, J. A. Harmon and R. W. Voedisch, issued 1958; U.S. Patent No. 2,809,954, 2. Ka∑enas, issued 1957; U.S. Patent No. 2,938,873, Z. Kazenas, issued 1960; and, U.S. Reissue Patent No. 25,845, G. F. D'Alelio and R. W. Voedisch.)

Since the early 1960'ε, sulfona ide-based fluorescent pigments have become the workhouse daylight fluorescent pigments of the industry. Resins based on sulfonamide have a high refractive index, break cleanly without sharp edges, exhibit resistance to weatherability and to water and are generally resistant to oil, gasoline, etc.

Other types of resin carriers include the polyesters, polyamideε, polyacrylics and alkydε as well as amino aldehyde resins, such as the previously described melamine and urea resins as well as bεnzoguanamine formaldehyde resins.

Resins based on a sulfonamide isocyanate reaction incorporating fluorescent dyes have bee described by U.S. Patent No. 3,741,907, Beye 1in,

iεsued June 1973.

The phenomenon of daylight fluorescence is the result of the unusual property that fluorescent pigments have of absorbing light at specific frequencies and re-emitting this absorbed energy at longer wavelengths {i.e. , lower frequencies. )

The daylight fluorescent pigments of commercial value are those which exhibit fluorescence when exposed to radiation in both the ultraviolet and visible ranges. The emitted light in conjunction with the reflected colors combine to enhance the presence of the natural colors.

Of importance in the use of fluorescent pigments is the ability of the pigments to act as a substrate for the fluorescent dye. In this capacity, the pigment provides protection for the dye molecule and the desirable properties of light fastness and weatherability result.

Obviously, depending upon the physical characteristics of the fluorescent pigments (into which the required concentration of the fluorescent dye is suitably incorporated) , the procedure for producing commercially acceptable fluorescent colored

pigments becomes of great importance.

The infusable fluorescent colored pigments of the melamine urea, type are very difficult and expensive to grind to a suitable fineness.

The organic glass type modified sulfonamide resin matricies are not as difficult to grind to- a fine powder as the infusible resins mentioned above, In general, all the other types of solid resins suitable for use as fluorescent pigment carriers are also difficult to reduce to fine powder form to varying extents. It should also be pointed out that in the grinding-process considerable heat can be generated leading to decomposition of the resin carrier depending upon the conditions of grinding and heat evolved.

Daylight fluorescent pigments, producing unusually bright colors find use on highway billboardε, consumer packaging goods, magazine advertisements, sports and ski clothing and equipment, and in highway safety markings and in many textiie applications as well as special printing inks in security for currency, color coding and host of nthpr sfpjς .

In the production of paints and textile printing inks, etc. for use in the above-mentioned applications usually the process call for dispersing the daylight fluorescent pigments in the appropriate vehicle. In many instances this involves further shear resulting in the evolution of heat. The εulfona ideε based fluorescent colors, in particular, are troublesome during these operations due to their release of formaldehyde unless no formaldehyde has been used in some stage of the fluorescent color production process. Formaldehyde is a suspected human carcinogen and is being regulated very strictly due to environmental concerns in the workplace.

The prior art processes currently in existence for producing fluorescent colors (and fluorescent pigment colors) may be summarized as follows:

1. Grinding resin lumps where the fluorescent dye has already been incorporated in the resin in the molten state.

2. Adding the dye to a powdered resin.

3. Using a resin deposition method by, for example, precipitating the resin in a dye bath.

4. Incorporating the fluorescent dye in the resin during some type of emulsion polymerization or emulsion formation.

Disclosure of Invention

It is, therefore, an object of the present invention to provide a novel process for preparing a friable easily pulverizable aliphatic urethane foam in which the fluorescent dye has already been dispersed in the reactants employed or, alternatively, can be added after the pulverizing step.

Yet another object of the present invention is to provide a novel blowing agent, utilizing propylene oxide, which reacts with a urethane or isocyanurate foam forming process.

Yet a further object of the present invention is to provide a solvent having propylene oxide for reactive hydrogen containing compounds, such as epoxy resins, o-, -and 2~ ^s,ui fonamide epoxy resins, o-, - and p-sul onamide formaldehyde resins, and other sulfonamide which can be further reacted with isocyanates to produce urethane foams.

It is, yet, a further object of the present invention to provide a propylene oxide solvent for isocyanates to reduce the viscosity of prepolymers of isocyanates with various polyols.

It is a further object of the invention to provide a blowing agent, comprising propylene oxide, to replace environmentally hazardous Freons now in use.

It is still a further object of the invention to provide an improved process for the synthesis of easily pulverizable aliphatic urethane foams based on para- , meta- or ojrtho-sulfonamide resins, which contain fluorescent dyes, which do not decompose to give off formaldehyde during any stage of their processing and use.

It is a further object of the present invention to overcome the disadvantages inherent in the prior art.

The foregoing and related objects are achieved by a process which produces sulfonamide resins utilizing no formaldehyde or para-formaldehyde during their synthesis. The synthesis of these resins is achieved by using an in situ reaction of epoxy resins

up to a molecular weight of 20,000 with e.g., toluene sulfonamide, in the presence of a Lewis acid catalyst, followed by the further reaction with an aliphatic isocyanate and/or para-toluene sulfonyl isocyanate to obtain an NC0 containing prepolymer. During this reaction, the required quantity of fluorescent dye is incorporated into the molte 'mass.

This prepolymer is subsequently dissolved in propylene oxide and converted into an isocyanurate foam by using the appropriate catalyst and heat, if necessary. An advantage of using the aliphatic para- and meta-TMXDI are slow reacting compared to aromatic isocyanates. It should be noted that the use of silicon surfactants may be incorporated into the compositions of the invention, which may be produced by the process of the invention, if the end application so requires their use.

The epoxy sulfonamide resins are further reacted with other components, such as melamine and substituted mela ines, benzoguanamine, hydantion, N- aminoethyl piperazine, etc. , which confer added heat resistance and light stability to the end products. During the synthesis of these reεinε the fluorescent dye is added, usually in the range of 1 - 2., so as

to be uniformly dispersed throughout the mass of the reactants. These resins can be dissolved in various blowing agents (including, for example, propylene oxide) and urethane/isocyanurate foams produced by reaction of aliphatic isocyanates, such as tetramεthyl xylene diisocyanates by themselves or as suitable prepolymers.

Additionally, the compositions of the present invention may be used in combination with UV absorbers.

The foams used in the present invention can be conventional urethane foams produced by mixing two components; one component containing a reactive hydrogen composition and the other component being an isocyanate, preferably, with the fluorescent dye incorporated into one of the components before reaction.

The other type of foam is produced as an iεocyanurate foam using DMF-30 as a catalyst. In the production of these foams, conventional blowing agents may be used.

Numerous reactants may be used for preparation of the compounds of the present invention. Examples

of typeε of reactants are given below:

Epoxy Resins

The diglycidyl ether of bisphenol A with molecular weight of up to 20,000 and also diglydicyi ether of bisphenol F with molecular weights of up to 20,000.

Epoxy resins of a type where the polymer backbone is formed by vinyl co-polymerization and the epoxy groups are present and available for further reactions of the polymer with molecular weightε ranging up to 20,000.

Sulfonamide Resins

Epoxy sulfonamide resins prepared in situ where the sulfonamides can be benzenesulfonamide, toluenesulfonamide, naphthalenesulfona ide, sul ilamide, methanesulfonamide, ethanesulfonamide, phenylmetϊianesulfonamide, benzenedisulfon-amide and naphthalalenedisulfonamide.

lεocyanateε

Pre-polymers obtained by reaction with various epoxy sulfonamide resins which may contain other

reactants such as substituted a ino compounds, among others.

The following reactants may also be utilized, alone or in combination with one another:

Phenylεne diisocyanate, para-toluene sulfonyl isocyanate, tetramethyl xylene diisocyanates, tolyene diisocyanate, naphthalene-diisocyanate , bitoly diisocyanate, diisocyanate, tolylene diisocynate, dianiεidine diisocyanate, triphenylmethane triisocyanate, isocyanatomethyl-trimethyl-cyclohexyl isocyanate, diisocyanato-dicyclohexyl ethane, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate and iεocyanatophenylethyl-iεocyanate, among other reactants.

In addition to the foregoing groups of reactants, various polyols, such as adducts of sucrose, glycerine, pentaerythritol, etc., with propylene and/or ethylene oxides, as well as polyols, which can be derived from the degradation of re- claimed X-ray film (sans silver) and various polyamino compounds, such as N-aminoethyl piperazine, various aromatic and aliphatic diamines, such as paraphenylene diamine and pentamethylene diamine,

hydrazine and substituted hydra∑ines. Vinyl polymers and co-polymers with pendant NCO groups, for example, can be formed by the polymerization of m-iεopropeny - alpha, alpha-dimethylben∑yl isocyanate ( -TMI, available from the American Cyanamid Company} , and may also be used as reactants.

The invention will now be described in greater detail with reference being made to the following examples, which are presented as being merely illustrative of the present invention and are not intended as providing a definition of the scope thereof.

Example 1

In a two-liter three-neck flask fitted with an agitator and a thermometer along with the provision for blanketing with nitrogen gas, was set up with a heating mantle. To this was added 342 grams of pure para-toluene sulfonamide followed by 875 grams of a solid epoxy resin (a polymeric diglycidyi ether of bisphenol A) E.E.W. of 437.5.

The product was melted to a clear solution in approximately half-hour with stirring with a nitrogen blanket and slowly heated to 140°c. 400 mg of a 50%

solution of tetramethyi ammonium chloride in water was added and slow heating continued from this temperature with stirring and the heating mantle removed when an exotherm started to take place.

1.2 grams (1% by weight of reactants) of

Erillant Yellow GFF D352 fluorescent dye powder was stirred into the mass and the temperature allowed to rise to approximately 182 'C when the foaming subsided after about half-an-hour . It was allowed to cool to about 150 ^" C and 1 gram of dibutyl tin dilaurate (Witco Fromex UL—28) was added, followed by an addition of 50 grams of tetramethyi xylene diisocyanate (TMXDI) over a period of half hour maintaining the temperature at approximately 150 ^~ C.

The material was then poured out into an aluminium pan and allowed to cool. The mass had a greenish fluorescence. 20 grams of the above brittle product was dissolved in 25 grams of propylene oxide by stirring followed by an addition of 2 grams of water and 3 grams of N-aminoethyl pipera∑ine. To this entire mixture was added 6 grams of TMXDI and, after uniformly stirring the mixture it was slowly warmed to approximately one minute. After the reaction subsided, the foam was hard and brittle

enough to be very eaεily ground to a fine greeniεh, yellow fluorescent pigment.

Example 2

Example 1 waε repeated, except that at 140°C, 10 grams of melamine waε added to the mixture and the experiment continued with results similar to those obtained in Example 1.

Example 3

Example 1 was repeated, except that at 140°C, 10 grams of 2,4-diamino-6-phenyl-s-triazine was added to the mixture and the experiment continued with results similar to Example 1.

Example 4

Example 1 was repeated, except that along with the addition of TMXDI at 150°C over a half hour period of 3 grams of para-1oluene sulfonyl isocyanate was added and allowed to react keeping the temperature close to 150 C and the experiment was allowed to continue with similar results.

Example 5

Examples 1 through 4 were repeated, except that

during the foaming step, in the place of dibutyl tin dilaurate 5 grams of DMP-30 was stirred into the mass to be foamed and the mass waε heated to approximately 40" ^* C to obtain an isocyanurate foam in each case. The foam was friable and could very easily be ground to a powder which had a greenish yellow luorescence.

Example 6

Example 1 was repeated, except that 378 grams of a polymeric diglycidyl ether of bisphenol A was used as the epoxy resin with an Ξ.E.W. of 189. The amount of fluorescent dye was reduced to 0.8 grams. In this case, a very vigorous exotherm started at 150"C and 25 grams of TMXDI was added over a half hour period maintaining the temperature at 150 ^~ C. After this period, the material was poured into an aluminum pan and allowed to cool. The mass had a greenish yellow fluorescence.

20 grams of the above brittle product was dissolved in 25 grams of propylene oxide by stirring followed by 3 grams of N-aminoethyl piperazine and two grams of water. To this entire mixture was added 6 grams TMXDI and after uniformly stirring the mixture, it was slowly warmed to approximately 4θ'""C

when the foaming reaction began and was complete in approximately one minute. After the reaction subsided, the foam waε hard and brittle enough to be very eaεily ground to a fine greenish, yellow fluorescent pigment.

Example 7

Example 6 waε repeated, except that at 140°C, 10 gramε of melamine was added to the mixture and the experiment was allowed to continue with similar results.

Example 8

Example 6 was repeated, except that 10 grams of 2,4-diamino-6-phenyl-s-triazine waε added to the mixture and the experiment waε allowed to continue with similar resultε.

Example 9

Example 6 waε repeated, except that along with the addition of TMXDI at 150°C over a half hour period, 3 grams of para-toluene sulfonyl iεocyanate keeping the temperature cloεe to 150°C. The experiment was continued to completion with similar results.

Example 10

Examples 6 through 9 were repeated, except that during the foaming step in place of the dibutyl tin dilaurate 5 grams of DMP-30 was stirred into the mass to be foamed and the mass heated to approximately 40 C to obtain an isocyanurate foam in each case. The foam was friable and could very easily be ground to a powder which had a greenish yellow fluorescence.

While only several embodiments of the present invention have been shown and described, it will be obvious to those of ordinary skill in the art that many modi ications may be made to the present invention without departing from the spirit and scope thereof .