Fluorescent pigments

Fluorescent pigments have a mean particle size of from 8 to 16 lm and contain apolar polymer matrices based on polymethyl methacrylate, polystyrene, polybutadiene-modified polystyrene, polycarbonate, polyvinyl chloride or polyamide and one or more apolar fluorescent dyes of the coumarin or perylene series.

The present invention relates to novel fluorescent pigments whose mean 
particle size is from 8 to 16 mm, which are based on apolar polymer 
matrices selected from the group consisting of polymethyl methacrylate, 
polystyrene, polybutadiene-modified polystyrene, polycarbonate, polyvinyl 
chloride and polyamide and which contain one or more apolar fluorescent 
dyes of the coumarin or perylene series. 
U.S. Pat. No. 2,498,592 and U.S. Pat. No. 3,915,884 disclose fluorescent 
pigments which are based on dyes of the naphthalimide series and whose 
polymer matrices are polycondensates based on urea and formaldehyde or of 
polyamide. 
Furthermore, U.S. Pat. No. 2,938,873 describes fluorescent pigments whose 
dyes are of the naphthalimide or coumarin series and whose polymer 
matrices contain resins based on p-toluenesulfonamide and formaldehyde. 
However, it has been found that such fluorescent pigments have inadequate 
application properties, in particular an inadequate lightfastness. 
It is an object of the present invention to provide novel fluorescent 
pigments which are free of the abovementioned disadvantages. 
We have found that this object is achieved by the fluorescent pigments 
defined at the beginning. 
The novel fluorescent pigments contain one or more apolar fluorescent dyes 
of the coumarin or perylene series. 
Suitable apolar coumarin dyes are for example those described in U.S. Pat. 
No. 3,880,869, notably coumarin dyes of the formula III 
##STR1## 
where R.sup.5 and R.sup.6 are identical or different and each is 
independently of the other C.sub.1 -C.sub.4 -alkyl, in particular ethyl. 
Other especially notable fluorescent pigments contain coumarin dyes of the 
formula IV 
##STR2## 
where R.sup.5 and R.sup.6 are identical or different and each is 
independently of the other C.sub.1 -C.sub.4 -alkyl, in particular ethyl, 
and 
R.sup. is C.sub.1 -C.sub.11 -alkyl. 
Suitable apolar perylene dyes are for example those described in U.S. Pat. 
No. 4,618,694, DE-A-2,451,782, U.S. Pat. No. 4,379,934, U.S. Pat. No. 
4,446,324 and EP-A-227,980. 
Further suitable apolar perylene dyes are for example those described in 
EP-A-73,007. 
Preference is given to fluorescent pigments which contain dyes of the 
perylene series. 
Emphasis must be given to fluorescent pigments which contain perylene dyes 
of the formula V 
##STR3## 
where R.sup.8 is C.sub.1 -C.sub.13 -alkyl. 
Particular preference is given to fluorescent pigments which contain 
perylene dyes of the formula I 
##STR4## 
where R.sup.1 is hydrogen or cyano and 
R.sup.2 is C.sub.1 -C.sub.11 -alkyl. 
Particular preference is further given to fluorescent pigments which 
contain perylene dyes of the formula II 
##STR5## 
where R.sup.3 is C.sub.5 -C.sub.20 -alkyl which may be interrupted by an 
oxygen atom or is phenyl which is monosubstituted or polysubstituted by 
C.sub.1 -C.sub.13 -alkyl or C.sub.1 -C.sub.13 -alkoxy, and 
R.sup.4 is hydrogen, chlorine, phenoxy or halogen-, C.sub.1 -C.sub.4 
-alkyl- or C.sub.1 -C.sub.4 -alkoxy-substituted phenoxy. 
Preference is given in particular to fluorescent pigments which contain 
dyes of the formula II where R.sup.3 is C.sub.1 -C.sub.4 -alkyl- or 
C.sub.1 -C.sub.4 -alkoxy-monosubstituted or -polysubstituted phenyl and 
R.sup.4 is hydrogen, phenoxy or chlorine. 
Very particular emphasis must be given to fluorescent pigments which 
contain a dye of the formula I where each R.sup.1 is cyano and each 
R.sup.2 is butyl. 
Very particular emphasis must further be given to fluorescent pigments 
which contain a dye of the formula PG,5 II where R.sup.3 is 
2,6-diisopropylphenyl and R.sup.4 is phenoxy. 
Suitable R.sup.2, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 are for example 
methyl, ethyl, propyl, isopropyl, butyl, isobutyl and sec-butyl. 
R.sup.2, R.sup.7 and R.sup.8 may also be for example, like R.sup.3, pentyl, 
isopentyl, neopentyl, tert-pentyl, hexyl, 2-methylpentyl, heptyl, 
1-ethylpentyl, octyl, 2-ethylhexyl, isooctyl, nonyl, isononyl, decyl, 
isodecyl or undecyl. 
R.sup.3 and R.sup.8 may each also be for example dodecyl, tridecyl or 
isotridecyl. 
R.sup.3 may also be for example tetradecyl, pentadecyl, hexadecyl, 
heptadecyl, octadecyl, nonadecyl or eicosyl (The above names isooctyl, 
isononyl, isodecyl and isotridecyl are trivial names derived from the oxo 
process alcohols--cf. Ullmann's Encyklopadie der technischen Chemie, 4th 
edition, Volume 7, pages 215 to 217, and Volume 11, pages 435 and 436.), 
2-propoxyethyl, 2-isopropoxyethyl, 2-butoxyethyl, 2- or 3-methoxypropyl, 
2-or 3-ethoxypropyl, 2- or 3-propoxypropyl, 2- or 3-isopropoxypropyl, 2- 
or 3-butoxypropyl, 2- or 3-(2-ethylhexyloxy)propyl, 2- or 4-methoxybutyl, 
2- or 4-ethoxybutyl, 2- or 4-propoxybutyl, 2- or 4-isopropoxybutyl, 2-or 
4-butoxybutyl, 2- or 4-(2-ethylhexyloxy)butyl, 2-methyl-6-isopropylphenyl, 
2-methyl-6-sec-butylphenyl, 2-methyl-6-tert-butylphenyl, 
2-ethyl-6-isopropylphenyl, 2-ethyl-6-sec-butylphenyl, 
2-ethyl-6-tert-butylphenyl, 2-methylphenyl, 2,3-, 2,4-, 2,5- or 
2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2-methyl-4-methoxyphenyl, 
2,5-dimethyl-4-methoxyphenyl, 2-ethylphenyl, 2,6-diethylphenyl, 
2,6-diethyl-4-methylphenyl, 2-isopropylphenyl, 2,4-, 2,5- or 
2,6-diisopropylphenyl, 2-n-butylphenyl, 2-sec-butylphenyl, 
2-n-pentylphenyl, 2-n-hexylphenyl, 2-(2-methylpentyl)phenyl, 
2-n-octylphenyl, 2-methoxyphenyl, 2-ethoxyphenyl, 2,5-dimethoxyphenyl, 
2,5-diethoxyphenyl, 2,4-dimethoxyphenyl, 2,4-diethoxyphenyl, 
2,3-dimethoxyphenyl or 2,3-diethoxyphenyl. 
R.sup.4 may also be for example 2-, 3- or 4-fluorophenoxy, 2-, 3- or 
4-chlorophenoxy, 2-, 3- or 4-bromophenoxy, 2-, 3- or 4-tert-butylphenoxy, 
2-isopropyl-4-methylphenoxy, 2,3-, 2,4-, 2,5- or 2,6-dichlorophenoxy, 
2,4,5- or 2,4,6-trichlorophenoxy, 2-, 3- or 4-methylphenoxy, 2,3-, 2,4-, 
2,5-, 2,6- or 3,5-dimethylphenoxy, 2,5,6-trimethylphenoxy, 
2-methyl-4-chlorophenoxy, 2-methyl-5-chlorophenoxy, 
2-methyl-6-chlorophenoxy, 2-ethylphenoxy, 2,6-diethylphenoxy, 
2,6-diethyl-4-methylphenoxy, 2-isopropylphenoxy, 3-methyl-4-chlorophenyl, 
4-propylphenoxy, 4-butylphenoxy, 2-, 3- or 4-methoxyphenoxy, 2-, 3- or 
4-ethoxyphenoxy, 2-, 3- or 4-propoxyphenoxy, 2-, 3- or 
4-isopropoxyphenoxy, 2-, 3- or 4-butoxyphenoxy or 2,4-dimethoxyphenoxy. 
The fluorescent pigments according to the present invention are based on 
apolar polymer matrices selected from the group consisting of polymethyl 
methacrylate, polystyrene, polybutadiene-modified polystyrene, 
polycarbonate, polyvinyl chloride and polyamide. 
Preference is given under this condition to those fluorescent pigments 
having polymer matrices made of polymethyl methacrylate or polystyrene. 
The polymer matrices mentioned are known per se and are commercially 
available. 
The fluorescent dye content of the fluorescent pigments according to the 
present invention is in general from 1 to 3% by weight, based on the 
polymer matrix. 
The fluorescent dyes mentioned can be present in the novel fluorescent 
pigments either each on its own or else mixed with others. Similarly, the 
fluorescent pigments according to the present invention may contain only 
one of the polymer matrices mentioned or else mutual mixtures thereof. 
The novel fluorescent pigments are advantageously prepared by first 
incorporating the fluorescent dye into the polymer matrix, which is 
customarily in the form of granules, in a conventional manner, for example 
by extrusion or injection molding. If extrusion is chosen, the use of a 
twin-screw extruder will be found particularly advantageous. The process 
of incorporation generally takes place at 150.degree.-250.degree. C., 
preferably--if polymethyl methacrylate is used as polymer matrix--at 
200.degree.-240.degree. C. 
The colored plastics material resulting from the incorporation is then 
strand granulated, the resulting particles generally ranging in size from 
2 to 6 mm. These granules are then further comminuted, which is 
advantageously carried out in a conventional pin mill. Following this 
precomminution the granules usually have a size ranging from 0.8 to 1.2 
mm. 
Since the fluorescent pigments according to the present invention are to 
have a mean particle size ranging from 8 to 16 .mu.m, preferably from 10 
to 12 .mu.m, further comminution is necessary, which is advantageously 
carried out in a jet mill. It is particularly advantageous here to use a 
fluidized bed counterjet mill, for example a counterjet mill of the type 
GK-W 481 from Alpine. 
The novel fluorescent pigments are highly suitable for pigmenting 
waterborne paints and films and articles made of polyolefins, eg. 
polyethylene or polypropylene, and for printing fiber materials, for 
example fabrics in polyester or cotton or polyester/cotton blend fabrics. 
The novel fluorescent pigments possess high luminance and advantageous 
application properties, for example a high lightfastness and a low 
migration tendency.

The Examples which follow illustrate the invention. PMMA denotes polymethyl 
methacrylate. 
EXAMPLE 1 
10 g of 3,9-bis(isobutoxycarbonyl)-4,10-dicyanoperylene were incorporated 
into 1 kg of PMMA granules in a conventional manner by extrusion from a 
twin-screw extruder at 210.degree. C., and the extruded material was 
granulated. This product, which had a particle size of 4 mm in the longest 
dimension, was precomminuted in a pin mill. After precomminution the 
granules had a mean particle size of 1 mm. 
The precomminuted granules were introduced into a fluidized bed counterjet 
mill (counterjet mill of type GK-W 481 from Alpine) having a horizontally 
disposed sifting wheel. The operating conditions for the apparatus, which 
is operated with gaseous nitrogen, were: 
sifting wheel: 6700 r.p.m. 
gas pressure at jets: 4 bar 
air pressure at shaft: 0.45 bar 
air pressure at motor: 0.5 bar 
The product was a luminous bright yellow color. Cilas granulometry revealed 
a mean particle size of 11.7 .mu.m (volume distribution). 
EXAMPLE 2 
##STR6## 
were incorporated into PMMA at 210.degree. C. and the resulting material 
was ground into a luminous red pigment powder having a mean particle size 
of 10 .mu.m, both steps being carried out as described in Example 1. 
The fluorescent dyes listed in the table below were processed into 
fluorescent pigments as described in Example 1. 
__________________________________________________________________________ 
Concen- 
Ex- tration 
ample Polymer 
of dye [% 
No. Dye matrix 
by weight] 
Color 
__________________________________________________________________________ 
##STR7## PMMA 2 bluish red 
4 
##STR8## polystyrene 
2 bluish red 
5 
##STR9## PMMA 2 
##STR10## 
6 
##STR11## polystyrene 
2 
##STR12## 
7 
##STR13## PMMA 2 
##STR14## 
8 
##STR15## 
##STR16## 
2 
##STR17## 
9 
##STR18## polystyrene 
2 orange 
10 
##STR19## PMMA 2 orange 
11 
##STR20## PMMA 3 orange 
12 
##STR21## PMMA 2 orange 
13 
##STR22## PMMA 2 luminous red 
14 
##STR23## polystyrene 
2 luminous red 
15 
##STR24## PMMA 3 deep 
__________________________________________________________________________ 
red 
EXAMPLE 16 
(Application) 
40 g of the fluorescent pigment prepared as described in Example 2 were 
incorporated into a dispersion containing 760 ml of water, 30 g of 
polyacrylic acid, 30 g of an emulsifier based on a formaldehyde 
condensation product and 180 g of a binder based on polybutadiene by 
intensive stirring. The resulting homogeneous suspension was printed onto 
polyester/cotton blend fabric and fixed thereon at 115.degree. C. for 4 
minutes. This produced a luminous red print having particularly good wash 
fastness properties and an excellent lightfastness (4-5 on the blue 
scale). 
EXAMPLE 17 
(Application) 
5 g of a fluorescent pigment prepared as described in Example 2 were 
intensively mixed with 95 g of polyethylene granules, the mixture was 
extruded, and the extrudates were granulated. 
These granules were used on a blow molding machine to produce a 50 .mu.m 
thick polyethylene sheet which exhibited fluorescence at 613 nm. 
The sheet was suitable for promoting the growth of green plants. It was 
notable for good lightfastness and low dye migration.