Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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M-679
COMPOSITION AND PROCESS FOR ENHANCED DRAINAGE OF RESIDUAL
AQUEOUS RINSE ON THE EXTERNAL SURFACES OF PLASTIC PARTS
FIELD OF THE INVENTION
The present invention relates to compositions and
processes for rinsing plastic parts. Aqueous solutions of
polyethylene glycol esters with and without fluoride compounds
are effective at enhancing the drainage of residual rinse water
from the surfaces of the plastic parts.
BACKGROUND OF THE INVENTION
Plastic is painted for both cosmetic and functional
reasons. These reasons include protectlon against weathering and
fading, shielding electronic parts from electromagnetic and radio
frequency interferences and achieving a smooth finish.
In the automotive industry, the formed plastic parts
(fascia) used are often painted. This is to provide a smooth,
oftentimes metal-like finish. The paint covers molding and other
substrate imperfections. Decorative effects such as mirror
finishes9 texturing and color match of differently proce,ssed
parts are alsc achieved by painting.
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Most plastics need to be cleaned before painting them.
The most common contaminants that must be removed before painting
are mold release agents, shop soil, material handling soil,
machining soils, fingerprints and plastic sanding dust. These
contaminants are removed by chemical means such as detergents.
The process of cleaning plastic parts generally Pntails a
wash stage, a rinse stage and a f;nal rinse stage with deionized
water. The plastic part can be either spray washed or immersed
in the detergent. The most common processes are either an acidic
detergent wash stage followed by multiple rinse stages, or an
alkal;ne detergent stage, followed by a rinse stage, an acidic
detergent wash stage, and multiple rinse stages.
When the plastic part is to be painted, the cleaning
operation is performed in a production line with the freshly
cleaned part sequentially conveyed into the paint booth.
Problems can occur however, when the freshly cleaned part is not
fully dry. This can lead to "spotting" when painted and will
result in an imperfect paint job. This will require stripping of
the part and/or an additional painting procedure.
Removing the aqueous rinse water from the surface of the
plastic requires a drainage enhancing solution which will effec-
tively aid in drying the plastic part to be painted. The present
inventors have discovered an aqueous solution which will aid in
reducing spotting on the external surface of plastic parts.
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SUMMARY OF THE INVENTION
The present invention provides for a composition and
process for enhancing the drainage of residual aqueous rinse from
the external sur~aces of plastic parts comprising a polyethylene
glycol ester or mixtures of polyethylene glycol esters.
More preferrably, the present invention provides for a
composition and process for enhancing the drainage of residual
aqueous rinse from the external surfaces of plastic parts com-
prising a polyethylene glycol ester or mixtures of polyethylene
glycol esters and a fluoride compound.
The present invention effectively reduces the amount of
water on the external surfaces of plastic parts prior to their
painting. Any water left on the external surfaces can lead to
spots or imperfections in the final paint finish. This invention
is particularly effective for aiding the drainage of an aqueous
rinse from the external surfaces of virgin and rework plastic
used in the automotive industry.
DESCRIPTION OF THE RELATED ART
United States Patent 4,859,351, Awad, Au~ust 1989,
discloses a composition and process for reducing the coef~icient
of static frietiGn on the external surface of aluminum cans
consisting essentially of either an ethoxylated fatty acid, a
-- polyethoxyla~ed oleyl alcohol or an ethoxylated alkyl alcohol
phosphate ester.
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United States Patent 4,500,493, Scharf et al., December
1985, discloses a composition and method for reducing the liquid
residue remaining on a metal surface consisting of octane-1-phos-
phonic acid or water soluble salt thereof.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides for a composition and
process for enhancing the drainage of residual aqueous rinse from
the extern~l surfaces of plastic parts comprising a polyethylene
glycol ester or mixtures of polyethylene glycol esters.
More preferrably, the present invention provides for a
composition and process for enhancing the drainage of residual
aqueous rinse from the external surfaces of plastic parts com-
prising a polyethylene glycol ester or mixtures of polyethylene
glycol esters and a fluoride compound~
The polyethylene glycol esters are preferablr the water
soluble derivatives of a saturated fatty acid such as an ethoxy-
lated stearic acid, for example, polyethylene glycol monostearate.
Unsaturated fatty acids may also be used but are less preferable.
In the preferred treatment composition, depending upon the
chemistry of the detergent wash, the fluoride compound is added to
the drainage enhancing solution for several reasons. Fluoride ion
may combine with and remove ions causing hardness, such as calcium
and magnesium ions, which may be objectionable under a paint film.
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The fluoride ion may be used to track rates of addition of the
drainage enhancing solution through the use of an ion specific
electrode. Fluoride ion may also be used to suppress biological
activity.
The fluoride compound may be added to the polyethylene
glycol ester by means of any known fluoride compound. Examples
include alkali metal fluorides, such as sodium fluoride, ammonium
fluoride salts, such as ammonium fluoride and ammonium bi~luoride,
other inorganic fluoride salts and hydrofluoric acid, HF.
The polyethylene glycol ester and fluoride are preferably
blended together in an aqueous medium, such as deionized water, at
various concentrations. The ester may be added to the aqueous
medium in the concentration of from about 1.0% to 10.0% by weight.
Typically, however, the concentration will be from about 2.5% to
about 5.0%.
The fluoride is present at a much smaller concentration,
typically between about 0.01% and about 0.5% by welght, as
~luoride.
The aqueous concentrate desi~nated treatment A in accordance
with the present invention comprises
3.0% by weight polyethylene glycol (MW=600) monostearate
0.5% by weight polyethylene glycol (MW=1000) monostearate
0.06% by weight ammonium fluoride in deionized water.
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The aqueous concentrate designated treatment B in
accordance with the present invention comprises.
3.0% by weight polyethylene glycol (MW=600) monolaurate
0.5% by weight polyethylene glycol (MW=1000) monostearate
0.06% by weight ammonium fluoride in deionized water.
The concentrate is dissolved within the aqueous medium in
a concentration o~ about 0.1% v/v to about 5.0% vtV.
Pre~erably, the total concentration of the polyethylene
glycol ester or mixtures of polyethylene glycol esters when the
inventive concentrate is employed ranges from about 0.001% to
about 0.5%, more preferably 0.004% to about 0.08~. The
concentration of the fluoride compound will range from about 0.3
parts per mill;on to about 40 parts per million per million parts
deionized water as fluoride ion.
It should be understood that the polyethylene glycol
ester and fluoride components may be added separately to the
aqueous rinse thus avoiding the preparation of a concentrate.
Either method is within the purview of this invention. The
process of applying the diluted concentrate may be either by
spraying the plastic part or by immersing the plastic part in
the diluted concentrate.
Most plastics are paintable with the appropriate
choice of paint. However, some plastics will not accept paint
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(poor "wet-out" or adhesion) regardless of the cleanliness of
their surfaces. Examples of plastics that are paintable and used
in the automotive industry include polycarbonate/polybutylene
terephthalate, polyphenyleneoxide/nylon 66, polyphenyleneoxide/
polybutylene terephthalate, polyether-polyester copolymer/poly-
butylene terephthalate, polycarbonate (both unfilled and glass
filled), polyphenyleneoxide (both unfilled and filled) and a
resin/glass material.
The invPntion will now be further described with
reference to a number of specific examples which are to be
regarded solely as illustrative, and not as restricting the
scope of the invention.
EXAMPLES
Automotive grade plastic in the form of virgin and rework
parts were cleaned in the following sequence:
Sta~ Ireatment SteP
1 3% Kleen 132 alkaline wash,
1 minute spray at 140F
2 Tap water rinse
3 1% Permatreat 325,
acidic wash 30 second spray at 130F
4 Tap water rinse
Deionized water rinse
Kleen 132 and Permatreat 325 are tradenames of Betz
Laboratories, Inc.
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To evaluate the efficacy of the inventive concentrate as
a rinse enhancer, dilute solutions of the concentrate were used
in place oF the deionized water spray rinse in Stage 5. The
results are reported in Table I. The concentrate evaluated was
Treatment A.
TABLE I
Concentration Observations
Deionized Water Heavy beading on virgin plastic
Some sheeting on rework plastic
0.3% v/v Heavy beading on virgin plastic
Improved sheeting on rework plastic
0.6% v/v Smaller beading on virgin plastic
Sheeting better on rework plastic
1.0% v/v 30% improvement, smaller beads on virgin plastic
30% sheeting on virgin plastic sheeting well on
rework plastic.
2 to 3 minutes after initial observations were made,
deionized water and 0.3% solution had water beads on the surface.
0.6% solution was almost completely drained of water while 1.0%
solution was even better.
From these observations, it can be seen that the inventive
treatment is effective at enhancing the drainaye of rinse water from
the surfaces of plastic parts.
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Quantitative tests were also performed to determ;ne the
efficacy of the inventive concentrates. A 4 inch by 3 inch
plastic piece (trade name, Xenoy, available from General Electric)
underwent the following processing:
Staqe Treatment Step
1 3% Kleen 132 alkaline wash,
1 minute spray at 140F
2 Tap water rinse
3 2% Permatreat 302 acidic wash,
30 second spray at 135F
4 Tap water rinse
Deionized water rinse
Kleen 132 and Permatreat 302 are tradenames of Betz
Laboratories, Inc.
To evaluate the inventive concentrates, dilute solutions
in deionized water were used in place of the deionized water in
Stage 5. The plastic part was weighed, processed as per the above
sequence, allowed to drain 1 minute, then reweighed. The results
for Treatment B are reported in Table II. Treatment B was also
tested with various levels of ammonium fluoride. These results
appear in Table III.
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TABLE II
Average % ~ater
Welght of Retained Reduction Compared
Test Solution Water Grams Per Part To Deionized Water
Deionized 1.2059
Water 0.8885
1.1573
0.9322
Treatment B 0.3155 70.0
0.5% 0.3130
Tr~atment B 0.2799 73.0
1.0% ~.2871
Treatment B 0.3864 67.3
1.5% 0.3000
These results clearly showed improved drainage with use of
the inventive composition. Treatment B caused the solution to
sheet on this plastic.
TABLE IIT
Weight of Retained
Test_Solution Water Grams Per Part
Deionized Water 1.046
Treatment B 1.5%
0 ppm F 0.2914
Treatm~nt B 1.5%
5 ppm F 0.2961
Treatment B 1.5%
50 ppm F 0.3504
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While this invention has been described with respect to
particular embodiments thereof, it is apparent that numerous other
forms and modifications of this invention w;ll be obv~ous to those
skilled in the art. ~
