Compositions – Compositions containing a single chemical reactant or plural... – Organic reactant
Patent
1986-09-18
1989-06-06
Clingman, A. Lionel
Compositions
Compositions containing a single chemical reactant or plural...
Organic reactant
252170, 252171, 252542, 252DIG8, C09D 900
Patent
active
048369500
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a liquid for removing printing and screen printing inks, in particular for cleaning screen printing frames.
The liquid of the invention, which is useful in solving all types of cleaning problems in the printing and screen printing industry without the use of dangerous substances, is characterized by consisting of an essentially anhydrous mixture comprising
(a) .gamma.-butyrolactone of the formula ##STR1## and/or N-methyl-2-pyrrolidone of the formula ##STR2## in an amount of 1-25%, preferably about 10% (v/v) as well as
(b) one or more propylene glycol derivatives selected among substituted propyl acetates of the general formula ##STR3## wherein R is hydrogen or alkyl having from 1 to 6 carbon atoms, and/or propylene glycol ethers of the general formula ##STR4## wherein R.sub.1 is alkyl having from 1 to 6 carbon atoms, and n is 1, 2 or 3, and optionally
(c) a diluent selected among aliphatic compounds having a flash point above 22.degree. C. and a content of aromatic compounds below 1% and/or
(d) a surfactant, the amount of components (b), (c) and (d) constituting 99-75% (v/v) of the liquid.
Dilution as well as universal cleaning or washing of printing and/or screen printing inks from stencils, printing plates, screen printing frames, rollers and the like was previously made by means of cleaning liquids, which either contain "dangerous substances", cf. e.g. the notice no. 147 issued by the Environmental Protection Agency on Mar. 16, 1981, or aromatic solvents the use of which involves considerable risk to the individuals working with these agents. In particular for the cleaning of old dried-up ink residues in offset and letterpress printing, mainly xylene- and toluene-based agents were used in the past, whose health effects are well-known. To this should be added that the known cleaning liquids frequently exhibit very low flash points, which partly entails that the liquids predominantly ignite easily, and partly may be an expression of a high volatility and thus increased potential health risk through aspiration of vapours. Thus, toluene has a flash point of only 5.degree. C.
The currently leading cleaning liquid for washing screen printing frames is thus "Pregan 240E" from Kissel & Wolf, West Germany, which has the following composition:
"Solvesso 100" from Esso Chemicals contains 99% aromates.
It has long been known that the diluent liquids for ink formulations recommended by the ink manufacturers, are based on solvents which contain dangerous substances and therefore require utmost care.
As regards the cleaning process, the task is even more difficult. Here, dried-up inks are often to be dissolved in order for these to be removed from the printing and screen printing apparatus. Some inks are easy to remove, while others are extremely difficult to handle, and the ink types used are moreover different at the individual graphic firms. Some inks are extremely pernicious because they consist of two-component systems. Such inks may be difficult to remove within an ordinary working day, unless cleaning liquids of a type involving health dangers are used.
Consequently, it was necessary in the past to keep the above-mentioned dangerous and easily ignitable cleaning liquids, because only such liquids have been found to be able to dissolve all the ink types in use.
The screen printing industry faces particular problems because the cleaning liquids able to remove all inks also tend to destroy the glue which is used in the mounting of screens on screen printing frames. Further, it is not possible to select water-based or strongly hydrophilic cleaning liquids at will because such liquids will tend to destroy the stencil emulsion.
The use of .gamma.-butyrolactone and/or N-methyl-2-pyrrolidone as a cleaning agent for printing inks is known. Thus, such use is described in the FR Patent Specification No. 2,354,377, but this specification deals with removal of the stencil itself and not the printing ink. An important property of a cleaning agent for removal of screen printing inks is that it d
REFERENCES:
patent: 2438038 (1948-03-01), Craver
patent: 3673099 (1972-06-01), Corby et al.
patent: 4276186 (1981-06-01), Bakos et al.
patent: 4664721 (1987-05-01), Valasek
Paint & Resin, vol. 53(5), Oct. 1983, J. E. Hamlin "New Propylene Glycol Ethers and Acetates", pp. 42, 46.
Encyclopedia of Chemical Technology, pp. 889-910.
Hansen Charles M.
Madsen Claus H.
Clingman A. Lionel
CPS KEMI ApS
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