Compositions incorporating titanium compounds

In has been desired to employ adhesion promoters in printing inks to promote the adhesion of the ink to a plastic substrate but hitherto the available adhesion promoters have tended to discolor the ink and in certain cases to produce an ink containing a somewhat objectionable odor. A new printing ink has been developed which is based on a polymeric binder, a solvent therefor and an adhesion promoting agent which is the reaction product of a titanium orthoester and either a monoalkyl phosphate or a dialkyl phosphate or a mixture thereof in such proportions that the molar ratio of titanium to phosphate expressed as Ti:P is from 4:1 to 1:2.

This invention relates to compositions and particularly to compositions 
incorporating titanium compounds, preferably printing inks. 
According to the present invention a printing ink comprises a polymeric 
binder, a solvent therefor and an adhesion promoting agent comprising the 
reaction product of a titanium orthoester and either a monoalkyl phosphate 
or a dialkyl phosphate or a mixture thereof in such proportions that the 
molar ratio of titanium to phosphate expressed as Ti:P is from 4:1 to 1:2. 
Preferably the ink includes a reaction product in which the molar ratio 
Ti:P is 2:1 to 1:1.5. 
It will be seen that the printing inks of the present invention basically 
include as an essential ingredient the reaction product of the titanium 
orthoester and of either a monoalkyl phosphate or dialkyl phosphate or 
their mixture in proportions such as described previously to provide the 
necessary and desirable molar ratio of Ti:P. Generally speaking the 
titanium orthoester from which the reaction product is provided has the 
general formula Ti(OR).sub.4 in which R represents an alkyl group which 
usually contains up to 8 carbon atoms. However preferably the alkyl group 
contains fewer carbon atoms than eight and it has been found that the most 
preferred compounds are based on alkyl groups containing 3 or 4 carbon 
atoms. It is of course possible that mixed alkyl orthotitanates may be 
used such as mixed isopropyl butyl titanate. 
Generally speaking the monoalkyl phosphate used to prepare the particular 
reaction product will have the general formula (R.sub.1 O)PO(OH).sub.2 and 
the dialkyl phosphate will have the general formula (R.sub.2 O)(R.sub.3 
O)PO(OH). In these two formulae R.sub.1, R.sub.2 and R.sub.3 each 
represents an alkyl group which can contain up to 10 carbon atoms but 
preferably contains no more than 5 carbon atoms. Preferably also R.sub.1, 
R.sub.2 and R.sub.3 are identical when mixed monoalkyl and dialkyl 
phosphates are to be used but this need not necessarily be so. Naturally 
if desired the dialkyl phosphate can include different alkyl groups. 
The reaction product comprising the adhesion promoting agent is prepared by 
mixing of the respective reactants in any order and, if desired, in the 
presence of a suitable solvent which if allowed to remain in the reaction 
mixture should be compatible with the ink into which the agent is to be 
mixed. Such solvents which have been found to be useful are alcohols such 
as isopropyl alcohol, butyl alcohol or industrial methylated spirits. 
Generally the reaction is carried out at room temperature with stirring 
and cooling, if necessary. 
As indicated previously the use of the reaction product of the titanium 
orthoester is of value in printing inks and not only have these products 
been found to act as adhesion promoters but they have a reduced tendency 
to discolor the ink and the ink is heat stable. The inks are odor free 
when compared with some existing printing ink compositions. 
The inks of the present invention which are of particular interest are the 
flexographic and gravure inks in which the polymeric binder is 
cross-linkable and is dissolved in an appropriate organic solvent therefor 
and typical binders used in such inks are those based on nitrocellulose or 
ester type modified cellulose, e.g cellulose acetate propionate. Often 
such polymeric binders are employed in mixed form with polyamides, 
polyurethanes or other resins. 
The ink also usually contains one or more pigments and or one or more dyes 
and typical pigments which can be used are the colored inorganic pigments, 
white inorganic pigments and colored organic pigments. Organic dyes can be 
used to render the ink an appropriate color and often are used in 
conjunction with an opacifying white inorganic pigment such as titanium 
dioxide. It will be seen however that the printing ink of the present 
invention need not necessarily include a pigment and/or a dye. 
The inks of the present invention usually contain the reaction product of 
the titanium orthoester in an amount of up to 10% by weight of the total 
weight of ink and preferably in an amount of 1 to 6% by weight of the ink. 
The inks of the present invention can contain other additives such as slip 
aids and plasticisers. 
The inks of the present invention are of particular use in printing 
substrates formed of polyethylene or co-extruded 
polypropylene/polyethylene film or sheets where adhesion of the ink to the 
substrate is particularly important. Other films such as polyvinylidene 
dichloride coated plastics material in which the use of the reaction 
products of the titanium orthoester in accordance with the present 
invention have been found to be beneficial in conferring heat stability in 
particular on the ink. 
The dissolution of a dialkyl pyrophosphate in an alcohol produces a mixture 
of a monoalkyl phosphate and a dialkyl phosphate. Accordingly the reaction 
product of the titanium orthoester and mixed monoalkyl and dialkyl 
phosphate can be produced by reacting a solution of a dialkyl 
pyrophosphate in an alcohol with the titanium orthoester. 
The invention is illustrated in the following Examples:

EXAMPLE 1 
To a round bottomed flask equipped with a stirrer, condenser and dropping 
funnel and containing 284 gms of tetraisopropyl titanate there was slowly 
added from the funnel 203 gms of a commercial mixture of approximately 
equi-molar proportions of monoamyl phosphate and diamyl phosphate. The 
contents were stirred with the flask in a cooling bath until the addition 
was complete. 
An ink was made from the following ingredients in a ball mill 
______________________________________ 
parts by weight 
______________________________________ 
Nitrocellulose (Dry wt) 
5.05 
Polyurethane resin 6.72 
Rutile TiO.sub.2 15.54 
Dicyclohexyl phthalate 
5.46 
Polyethylene wax 2.00 
Isopropanol 2.16 
Industrial methylated spirits 
22.02 
Ethyl acetate 26.17 
Toluene 14.88 
100.00 
______________________________________ 
The 100 parts by weight of the above ink there was added 1 part by weight 
of the reaction product by weight of the prepared reaction product. The so 
prepared ink was used to prepare and test a printed strip of co-extruded 
polythylene/polypropylene and for comparison the ink without added 
reaction product was used to print an adjacent area of the strip. A sticky 
tape, (7.6 cm wide) was applied to the printed strip to contact both ink 
surfaces and pressure applied to ensure good contact. 
The tape was then quickly removed from both inks simultaneously and a 
visual inspection made of the strip. It was apparent that little or no ink 
containing the titanate was removed whereas virtually all the unmodified 
ink was removed by the sticky tape. 
Samples of co-extrudate printed with both inks were mounted between sheets 
of aluminium foil and heated to approximately 160.degree. C. for 10 
seconds. The heated samples were allowed to cool and the foil removed and 
inspected. It was clear that less of the modified ink had become 
transferred to the foil than that of the unmodified ink. 
EXAMPLE 2 
A titanate was prepared in a manner similar to that described in Example 1 
from 340 gms of tetra-n-butyl titanate and 182 gms of an approximately 
equi-molar mix of monobutyl phosphate and dibutyl phosphate. 
The titanate was used to prepare an ink in a similar manner to that of 
Example 1 and tested similarly. 
Again the modified ink exhibited improved adhesion and heat resisting 
properties. 
EXAMPLE 3 
A titanate was prepared in apparatus as described in Example 1 from 340 gms 
of tetra-n-butyl titanate and 154 gms of monobutyl phosphate dissolved in 
308 gms industrial methylated spirits with vigorous stirring. 
The titanate solution was used to prepare an ink similar to that of Example 
1 except that 1.5 parts by weight of the solution was added and tested 
similarly. 
The modified ink was shown to have similar improved properties to those of 
Examples 1 and 2. 
EXAMPLE 4 
A titanate was prepared using the apparatus of Example 1 from 340 gms of 
tetra-n-butyl titanate and 210 gms of dibutyl phosphate. 
An ink was prepared similar to that of Example 1 using the titanate and 
tested similarly. 
Once more the modified ink exhibited superior adhesion and heat resistance 
compared with an unmodified ink. 
It was seen that the inks of all the previous Examples did not discolor on 
the addition of the titanate or upon storage thereafter. 
EXAMPLE 5 
A titanate was prepared in apparatus as described in Example 1 from 284 gms 
of tetraisopropyl titanate and 161 gms of an approximately equi-molar mix 
of a monoisopropyl phosphate and diisopropyl phosphate dissolved in 94 gms 
of industrial methylated spirits with vigorous stirring. 
The titanate was used to prepare an ink in a manner similar to that of 
Example 1 and tested similarly. 
The modified ink was shown to have similar properties to those of the 
modified inks of Examples 1, 2, 3 and 4. 
EXAMPLE 6 
A solution of mixed mono and dialkyl phosphates was prepared by reacting 
145 gms of butyl pyrophosphate with 54 gms of industrial methylated 
spirits. 
A titanate was prepared in apparatus similar to that described in Example 1 
by adding the above solution to 340 gms of tetra-n-butyl titanate with 
vigorous stirring. 
The titanate was used to prepare an ink in a manner similar to that of 
Example 1 and tested similarly. The modified ink exhibited improved 
properties similar to the modified ink of Examples 1, 2, 3, 4 and 5.