Liquid detergent composition

The liquid detergent composition of the invention comprises a halogenated hydrocarbon solvent, e.g. methylene chloride, an anionic and/or non-ionic surface active agents, a quaternary ammonium hydroxide, e.g. tetramethyl ammonium hydroxide and choline, and, optionally, a lower aliphatic alcohol, e.g. methyl alcohol, each in a limited proportion. The detergent composition is very effective in the cleaning works of articles of a transparent plastic resin, e.g. polycarbonate resin, and metal or glass molds for the preparation of such resin articles by casting polymerization, of which uppermost cleanness on the surface is very essential in respect of oily, greasy and resinous contaminants.

BACKGROUND OF THE INVENTION 
The present invention relates to a liquid detergent composition or, more 
particularly, to a liquid detergent composition comprising a halogenated 
hydrocarbon solvent as the principal component suitable for cleaning the 
surface of various articles stained with oily, greasy or resinous 
contaminants. 
Needless to say, several shaped articles of plastics are required to have 
extremely high cleanness on the surface in view of their use including, 
for example, plastic-made eye glasses and lenses in various optical 
instruments usually shaped by the method of casting polymerization of 
polycarbonate resins, poly(methyl methacrylate) resins, diethyleneglycol 
bisallylcarbonate resins and the like transparent plastics. These 
plastic-made articles as shaped are usually not free from contamination or 
stain on the surface, for example, with smears or fragment pieces of the 
plastic or perspiration and other excretions from the skin of the workers 
as in fingerprints as well as dirty matters coming from the working 
gloves. Accordingly, it is usual that the surfaces of these plastic 
articles are thoroughly cleaned using a detergent composition before they 
are packaged and shipped as commercial products. 
In addition, although the requirement for the surface cleanness is not so 
rigorous as in the above mentioned plastic articles for optical uses, it 
is of course desirable for any articles shaped with the above mentioned 
resins that the surface should be fairly clean from the standpoint of 
commercial value of these transparent plastic articles while it is a 
rather difficult problem because the metal or glass molds used for the 
casting polymerization of these resins usually cannot be clean enough so 
that the plastic articles shaped with such an unclean mold are also not 
acceptable in respect of the surface cleanness. Therefore, it is essential 
that the metal or glass mold used for the casting polymerization of the 
above mentioned resins is thoroughly cleaned using a detergent composition 
after each time of the casting polymerization runs to prepare for the next 
use to be freed from any contaminants and dirty matters including plastic 
debris or fragment, greases, fingerprints and the like. 
As a consequence of the nature of the stain or contaminant on the surface 
of the above mentioned plastic articles or molds used for the preparation 
thereof, which is usually oily, greasy or resinous, it is a common 
practice that an organic solvent is used as a detergent for the cleaning 
works in the above mentioned cases. For example, various kinds of 
halogenated hydrocarbon solvents, such as methylene chloride, 
1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene and the 
like, are widely used for the purpose by virtue of their high detergent 
power along with the non-inflammability. Methylene chloride is 
particularly preferred due to its relatively low toxicity to the human 
body. These organic solvents, however, are not quite powerful as a 
detergent for the cleaning works in the above mentioned cases so that 
complete cleaning is hardly possible even by a prolonged washing with the 
solvent. Therefore, it is a usual practice that cleaning of the stain or 
contaminant with these halogenated hydrocarbon solvents is followed by 
manual wiping works of the surface with a cloth wet with acetone, alcohol 
or other solvent resulting in a great decrease in the productivity of the 
overall production process. 
Accordingly, it is eagerly desired to develop a detergent composition with 
which a high efficiency is obtained in the cleaning works of the 
plastic-made articles and the molds for the preparation thereof. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to provide a novel and 
improved liquid detergent composition with which a very high efficiency is 
obtained in the cleaning works of the surfaces of shaped articles made of 
the above mentioned plastic resins as well as metal or glass molds used 
for the preparation thereof. 
Another object of the invention is to provide a liquid detergent 
composition comprising, as the principal component, a halogenated 
hydrocarbon solvent and usable in the above mentioned cleaning works 
without the necessity of following manual wiping with a cloth wet with 
another organic solvent to clean up the surface. 
Thus, the liquid detergent composition of the invention comprises: 
(a) a halogenated hydrocarbon solvent as the base component; and 
(b) a surface active agent selected from the group consisting of anionic 
and non-ionic surface active agents in an amount from 0.01 to 10% by 
weight of the detergent composition. 
Further, it is preferable that the liquid detergent composition 
additionally comprises from 0.001 to 20% by weight of a quaternary 
ammonium hydroxide. 
Still further, it is also preferable that the inventive liquid detergent 
composition additionally comprises from 1 to 20% by weight of a monohydric 
aliphatic saturated alcohol having 6 or smaller number of carbon atoms in 
a molecule. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As is understood from the above description, the principal component of the 
inventive liquid detergent composition is a halogenated hydrocarbon 
solvent which is admixed with one or more of the above mentioned additives 
to form the inventive liquid composition. The halogenated hydrocarbon 
solvent suitable in the inventive liquid composition is exemplified by 
methylene chloride, 1,1,1-trichloroethane, trichloroethylene, 
tetrachloroethylene and the like, of which methylene chloride is 
particularly preferred by virtue of the excellent cleaning power and low 
toxicity as well as the non-inflammability to ensure high efficiency and 
safety in the cleaning works. 
The essential additive in the inventive liquid detergent composition based 
on the above defined halogenated hydrocarbon solvent is a surface active 
agent which can be either anionic or non-ionic. A combination of these two 
types of surface active agents can be used or is rather preferable in some 
cases. Suitable anionic surface active agents include, for example, salts 
of alkylsulfate esters, salts of alkylbenzene sulfonates, salts of 
alkylsulfosuccinates, salts of alkylphosphate esters, salts of 
polyoxyethylene alkyl phenyl ether sulfates and the like and suitable 
non-ionic surface active agents include polyoxyethylene alkyl ethers, 
polyoxyethylene alkyl phenyl ethers and the like. The amount of the 
anionic and/or non-ionic surface active agents in the inventive liquid 
detergent composition should be in the range from 0.01 to 10% by weight 
or, preferably, from 0.1 to 5% by weight of the composition, the balance 
being the halogenated hydrocarbon solvent and other optional additives, if 
any. 
In addition to the above described anionic and/or non-ionic surface active 
agents as an essential additive, the inventive liquid detergent 
composition may preferably contain a quaternary ammonium hydroxide such as 
tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, choline, 
trimethyl benzyl ammonium hydroxide and the like whereby the detergent 
power of the inventive composition can be further increased. The amount of 
the quaternary ammonim hydroxide should be in the range from 0.001 to 20% 
by weight of the composition, the balance being the halogenated 
hydrocarbon solvent, the anionic and/or non-ionic surface active agents 
and other optional additives. 
Although the content of the quaternary ammonium hydroxide in the inventive 
liquid detergent composition should be, as is grossly given in the above, 
in the range from 0.001 to 20% by weight, the exact amount thereof should 
be selected according to the intended application of the detergent 
composition. When the intended application of the composition is for the 
cleaning works of plastic-made shaped articles per se, for example, the 
preferable amount of the quaternary ammonium hydroxide is relatively 
small, for example, in the range from 0.001 to 0.2% by weight or, more 
preferably, from 0.01 to 0.1% by weight. This is because a large amount of 
addition of the quaternary ammonium hydroxide increases the dissolving 
power of the composition to a resinous material so that, in addition to 
the oily or greasy stain or contaminants, the surface of the plastic-made 
shaped article per se may be attacked by the detergent composition to 
cause decrease in the beautiful appearance of the article. 
When the intended application of the inventive liquid detergent composition 
is for the cleaning works of, for example, metal or glass mold used for 
the preparation of plastic articles, on the other hand, it is of course 
desirable that any trace amount of the resinous contaminant should be 
dissolved away as completely as possible so that the detergent composition 
should have a full power of dissolving resinous materials. In this regard, 
the amount of the quaternary ammonium hydroxide should be relatively high 
within the upper limit of 20% by weight. Accordingly, the preferable 
amount of the quaternary ammonium hydroxide in the detergent composition 
for such an application is in the range from 0.1 to 20% by weight or, more 
preferably, from 0.2 to 2% by weight in view of the balance of the 
detergent power and the cost due to the increased content of the 
relatively expensive quaternary ammonium hydroxide. 
A further optional aditive component in the inventive liquid detergent 
composition is a monohydric aliphatic saturated alcohol having 6 or 
smaller number of carbon atoms in a molecule exemplified by methyl, ethyl, 
isopropyl, n-butyl and hexyl alcohols, of which methyl alcohol is 
particularly preferred. The addition of these alcohols is effective to 
increase the detergency of the composition to the contaminants having 
polar nature such as the perspiration and other excretions, e.g. proteins, 
originating in the worker's body. The amount of the alcohol as the 
additive should be in the range from 1 to 20% by weight or, preferably, 
from 2 to 20% by weight of the composition. 
In addition to the above described additives directly pertaining to the 
detergent power of the inventive liquid composition, it is of course 
optional that the inventive liquid detergent composition contains limited 
amounts of one or more of other additives having no direct influence on 
the detergent power of the composition such as a stabilizer of the 
halogenated hydrocarbon solvent exemplified by epoxides such as propylene 
oxid, butylene oxide and the like, amine compounds such as 
diisopropylamine, isopropylamine and the like and nitroalkane compounds 
such as nitromethane, nitroethane and the like. 
The inventive liquid detergent composition can be obtained by merely 
blending the above described components in the respectively specified 
proportions and dissolving or dispersing the additive components in the 
halogenated hydrocarbon solvent. When a relatively large amount of the 
quaternary ammonium hydroxide is used, however, it is preferable that the 
quaternary ammonium hydroxide is first dissolved in a small volume of 
water or a lower alcohol such as methyl and ethyl alcohols and the aqueous 
or alcoholic solution is added to the composition. In the case of using an 
aqueous of alcoholic solution of the quaternary ammonium hydroxide, the 
amount of water or alcohol as the solvent thereof should be limited. For 
example, the overall amount of the water and alcohol should not exceed 20% 
by weight or, preferably, 10% by weight of the composition. Due to the 
immiscibility of water with the halogenated hydrocarbon solvent as the 
base component of the composition, the resultant liquid detergent 
composition may be a binary-phase composition which may be separated on 
standing into organic and aqueous layers, the former being the upper layer 
and the latter being the lower layer. The detergent power of the inventive 
liquid detergent composition is, however, not affected even when the 
composition is separated into two layers as mentioned above. Moreover, to 
the contrary, an advantage is obtained with such a binary-phase 
composition that the evaporation loss of the highly vaporizable methylene 
chloride or other halogenated hydrocarbon solvent can be minimized in 
storage because the surface of the composition in standing is covered with 
the separated aqueous layer. 
As is understood from the above description, the inventive liquid detergent 
composition can be imparted with a controlled detergent power according to 
the nature of the contaminant to be cleaned in respect of the solubility 
or polarity by suitably selecting the amounts of the additive components 
so that the troublesome process of manual wiping of the articles after 
cleaning with the liquid detergent composition can be omitted greatly 
contributing to the improvement of the productivity of plastic-made 
articles and other goods in which surface cleanness is essential.