Note: Descriptions are shown in the official language in which they were submitted.
1 33~487
This invention relates to a cleaning resin composition
used for cleaning the inside of various molding machines.
More particularly it relates to a cleaning resin composition
obtained by blending a neutral salt of an
alkylbenzenesulfonic acid, an inorganic filler and a water-
repellent compound with a polyolefin resin.
~ ece~t molding of thermoplastic resins has been more and
more diversified and production of more grades in smaller
quantities has been intended. Further, due to appearance of
engineering plastics, etc., color exchange or resin exchange
inside molding machines has been carried out within a broad
temperature region, and the frequency of the color exchange
or resin exchange has also been increasing.
Heretofore, at the time of such color exchange or resin
exchange, in order to remove contaminants caused by the
pr~c~ing resin inside the molding machine i.e. in order to
clean the inside of the molding machine, the following
processes have been employed:
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v~._
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a process of drawing out the contaminated screw
inside the molding machine, followed by scraping off
the contaminants on the screw or the inner wall of
the cylinder by means of a brush or the like i.e. the
so-called hand sweeping, or a process of flowing
a colorless resin (hereinafter abbreviated to cleaning
resin) through the inside of the cylinder to clean
the screw together with the cylinder (hereinafter
referred to as co-cleaning) without drawing out the
screw.
However, such processes require a long time for
completely cleaning the screw and the inside of the
cylinder, and in the case of the co-cleaning, a large
quantity of cleaning resins is used to cause a large
loss in the economical aspect.
Thus, in order to solve such problems, a cleaning
agent composed mainly of a hard resin such as acrylic
resins, a cleaning agent obtained by blending a nonionic
surfactant with a thermoplastic resin, a cleaning agent
obtained by blending a lubricant such as stearic acid
with a thermoplastic resin, etc. have been developed.
However, in the former case, since the acrylic
resins have high melt viscosity, a high load is applied
at the time of cleaning the inside of the molding
machine and also it is necessary to raise the temperature
of the molding machine up to a considerably high
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temperature, there is a drawback that the resins are
susceptible to thermal decomposition.
Further, there are drawbacks that operations are
troublesome and require a considerably long time, for
example, before the cleaning agent is used, the die
screen pack, etc. of the molding machine should be
removed, and further if the cleaning agent remains
inside the molding machine after completion of the
cleaning, the remaining cleaning agent mixes in the
molded product of the succeeding resin so that the agent
in the form of a foreign matter deteriorates the appear-
ance or the physical properties of the molded product.
On the other hand, in the latter case, the cleaning
agent obtained by blending stearic acid or the like
with a thermoplastic resin is insufficient in the
cleaning effect inside the molding machine, and in
the case of the cleaning agent obtained by blending
a nonionic surfactant with a thermoplastic resin, if
the service temperature of the cleaning agent exceeds
250C, vigorous evolution of decomposition gas occurs
and also a characteristic odor occurs to have a bad
influence upon the operational environment, and further
the cleaning effect is insufficient with such a cleaning
agent.
1 336487
The present inventors have made extensive research in
order to obtain a cleaning resin composition by the use of
which it is possible to effect color exchange inside various
molding machines by exchanging the composition for the
preceding colored resin or to clean the inside of the
machines or to effect resin exchange for the preceding resin
inside the machines, in a small quantity of the composition,
in a simple operation and in a short time.
As a result we have found that a composition obtained by
blending a neutral salt of an alkylbenzene-sulfonic acid, an
inorganic filler and a water-repellent compound with a
polyolefin resin is a cleaning resin composition capable of
solving the above-mentioned problems and have achieved the
present invention based on this finding.
In one aspect the present invention provides a cleaning
resin composition comprising a polyolefin resin, a neutral
salt of an alkylbenzenesulfonic acid, an inorganic filler
selected from talc and calcium carbonate, and a water-
repellant compound blended with said polyolefin resin,wherein the proportions of said neutral salt of an
alkylbenzenesulfonic acid, said inorganic filler and said
water-repellant compound are 1 to 20%, 1 to 30% and 0.5 to
10% each, respectively, by weight, based on the weight of
said composition.
Preferably, the polyolefin resin is polyethylene or
polypropylene. Suitably, the cleaning resin composition is
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-- 5
in the form of pellets obtained by melt-kneading.
Examples of the polyolefin resin used in the present
invention are polyethylene resins such as high density
polyethylene, linear low density polyethylene, low density
polyethylene, etc., polypropylene resins such as crystalline
propylene homopolymer, crystalline propylene-ethylene
copolymer, crystalline propylene-ethylene-butene-l terpolymer
or crystalline propylene-butene-1 copolymer each containing
70% by weight or more of propylene component, polybutene-1,
non-crystalline ethylene-propylene copolymer (EPR), non-
crystalline ethylene-propylene-diene terpolymer (EPDM) and
mixtures of the foregoing. Among these, preferred resins are
high density polyethylene, linear low density polyethylene,
crystalline propylene homopolymer, crystalline propylene-
ethylene copolymer, crystalline propylene-ethylene-butene-1
terpolymer and mixtures of the foregoing.
1 336487
As the neutral salt of an alkylbenzenesulfonic acid used
in the present invention, sodium salt of an
alkylbenzenesulfonic acid is preferably used. This sodium
salt of an alkylbenzenesulfonic acid is one kind of anionic
s surfactants and its decomposition-initiation temperature is
as high as 300C. Examples of suitable alkyl groups for the
neutral salt of an alkyl benzenesulfonic acid include linear
or branched alkyl ~LO~S of C8 to C2Q.
Thus, the surfactant displays a powerful effect upon
cl~ning of the inside molding machi~ec even within a high
temperature region; thus a superior cleaning effect is
exhibited over from a low temperature region to a high
temperature region.
The guantity of the neutral salt of an
alkylbenzenesulfonic acid blended is preferably 1 to 20% by
weight, more preferably 5 to 15% by weight based on the
weight of composition. If the quantity thereof blended is
less than 1% by weight, the cleaning effect is small when the
inside of molding machines is cleaned with the resulting
composition, while if it exceeds 20% by weight, notable
foaming occurs when the resulting composition is granulated.
Examples of the inorganic filler used in the present
invention are calcium carbonate or talc.
-- 6 --
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1 336487
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In the cleaning composition, the inorganic filler
exerts a function of rubbing of L dirties in the molding
machine and the preceding resin adhered thereonto through
a mechanical force. The quantity thereof blended is
preferably l to 30% by weight, more preferably 5 to 20%
by weight based on the weight of the composition. If
the blended quantity is less than 1% by weight, the
cleaning effect is insufficient, while if exceeds 30%
by weight, the melt-fluidity of the resulting cleaning
resin composition is reduced and too a large load is
applied onto the molding machine at the time of cleaning.
Examples of the water-repellent compound used in
the present invention are synthetic waxes such as poly-
ethylene wax, silicones, natural waxes, metal salts of
higher fatty acids and mixtures of the foregoing. The
quantity of the water-repellent compound blended is
preferably 0.5 to 10% by weight, preferably 2 to 10~
by weight. In the cleaning resin composition of the
present invention, the water-repellent compound exerts
a lubricating function. If the quantity of the water-
repellent compound blended is less than 0.5% by weight,
the lubricating effect is small, while if it exceeds
10% by weight, the lubricating properties are so strong
that the mechanical force of the coexistant inorganic
filler inside the molding machine is reduced.
1 336487
Phenolic antioxidants, thioic antioxidants,
phosphorus antioxidants, etc. usually blend with poly-
olefin resins may be blended.
The composition of the present invention may be
obtained by introducing a polyolefin and definite
quantities of a neutral salt of an alkylbenzenesulfonic
acid, an inorganic filler and a water-repellent compound
and further at least one member of the above-mentioned
antioxidants into an agitating and mixing device such
T~ ~r~ rk
as Henschel mixer (tr~dcnamo), super mixer, etc. and
agitating and mixing these materials for one to 5 minutes.
Further, the resulting mixture may be subjected to melt-
kneading and extruding at a melt-kneading temperature of
180 to 220C, preferably 190 to 210C by means of
a single screw extruder or a twin-screw extruder into
pellet form.
The present invention will be described in more
detail by way of Examples and Comparative examples, but
it should not be construed to be limited thereto. In
addition, the proportions therein refer to % by weight.
Examples 1 - 5 and Comparative examples 1 - 4
The respective blending components described in
Table 1 mentioned later were introduced into a Henschel
~ r~de ~n.zrl~
mixer (tradcnamc), followed by agitating and mixing
them for 3 minutes, melt-extruding the resulting
1 336487
g
mixture at a melt-kneading temperature of 210C by
means of an extruder having a bore diameter of 35 mm
and provided with a vent and extruding the resulting
material into pellet form to obtain a cleaning resin
composition of the present invention. Further, in
Comparative examples 1 - 4, the respective blending
components described in Table 1 mentioned later were
agitated and mixed and melt-kneaded in the same manner
as in Examples 1 - 5 to obtain pellets. With the
cleaning resin compositions obtained in these Examples
and Comparative examples, 1) cleaning of an injection
molding machine and 2) cleaning of a blow molding machine
were carried out in a manner of thegist described below,
respectively.
Table 1
Example Example Example Example Example Comp. Comp. Comp. Comp.
1 2 3 4 5 ex. 1 ex. 2 ex. 3 ex. 4
High density 60 0 68 5 75.0 - 35.0 - 76.0
polyethylene
Linear low density _ _ _ _ 69.0% - 41.0
polyethylene
Polypropylene 75.0% - - - - - - - 88.0
Na alkylbenzene- 1.5 - 7.5 - - 4.0 16.0 9 0
sulfonate
K alkylbenzene- 7 5 14.5 _ 19.5
sulfonate
Polyoxyethylene 5 0
cetyl ether
Ca carbonate - 28.5 - 15.0 - 50.0 51.0 - - Y
Talc 15.0 - 8.5 - 1.5 - - - -
Polyethylene wax 2.0 9.5 2.5 2.5 - - - 6.0
Zn stearate - 0.5 3.0 - 8.0 10.0 2.0
Na stearate 0.5 - 3.0 - 2.0 - 2.0 - -
Silicon dioxide - - - - - - - 2.0 1.O C~
Ca stearate - - - - - - - - 2.0 Co
~: by weight
1 336487
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1) Example of cleaning of injection molding machine:
Black resin pellets of any of ABS resin, PPS resin
and modified PPO resin, difficult in color exchange,
were injection-molded by means of a 35 tons injection
molding machine in 50 shots, followed by cleaning
the inside of the molding machine with cleaning resin
compositions obtained in Examples 1-5 and Comparative
examples 1-4, each in 100 g, by injection molding and
repeating injection molding with a colorless polypro-
pylene resin as a cleaning resin by the injection moldingmachine until the resulting molded products were not
colored, to obtain the total quantity of the cleaning
resin required therefor.
Further, the black ABS resin was injection-molded
under the same conditions and repeating injection-
molding with the colorless polypropylene resin as
a cleaning resin without using the above-mentioned
cleaning resin compositions until the resulting molded
product was not colored, to obtain the total quantity
of the cleaning resin required therefor. These results
are collectively shown in Table 2.
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Table 2
Cleaning resin Quantity of cleaning
Colored composition resin used
resin Tempera- Case of use Case of non-
Kind ture at of the com- use of the
its use position composition
Black of Ex. 4 320C600 (g) 3270 (g)
modified that of " 2110 "
PPO resin Comp. ex. 1
1) that of " 2400
Comp. ex. 3
that of " 560 3120
Black Ex. 3
PPS resin that of .. 2050 "
that of .. 2250
Comp. ex. 3
that of 300C 100 910
Ex. 4
that of .. 580
Comp. ex. 1
Black that of " 600
ABS resin Comp. ex. 3
3) that of 120
Ex. 1
that of .. 620
Comp. ex. 2
that of " 590 "
Comp. ex. 4
that of 260OC 140 1230
that of .. 180
Ex. 3
that of .. 190
Black Ex. 2
ABS resin that of " 740 ..
Comp. ex. 1
that of .. 760
Comp. ex. 2
that of " 700 ..
Comp. ex. 3
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Table 2 (continued)
Cleaning resin Quantity of cleaning
Colored composition resin used
resin Tempera- Case of use Case of non-
Kind ture at of the com- use of the
its use position composition
composition 230C 260 1410
that of " 300 "
Ex. 3
Black that of " 320 "
ABS resin Ex. 5
that of
Comp. ex. 1 " 860 "
that of ~ 980
Comp. ex. 3
that of 230C 240 1305
that of ~ 220
Black Ex. 4
PP resin that of " 840 "
4) Comp. ex. 1
Comp. ex. 3 910 "
that of 200C 360 1820
Ex. 4
that of ~ 380
Black Ex. 1 _
ABS resin that of " 1000 "
Comp. ex. 2
Comp. ex. 3 1270 ..
1) Polyphenylene oxide 2) Polyphenylene sulfide
3) Acrylonitrile-butadiene-styrene copolymer
4 ) Polypropylene
- 14 - I 33 648 7
2) Exmaple of cleaning of blow molding machine:
Black resin pellets of either one of ABS resin or
polyethylene reisn difficult in color exchange were
extruded in 10 parisons (one parison: ca. 200g) by
means of a blow molding machine having a die diameter
of 21 mm and a core diameter of 19 mm, followed by
cleaning the resulting blow molding machine with the
cleaning resin compositions obtained in Examples 1-5
and Comparative example 1-4, each in 2,000 g, and then
molding the parisons with a colorless polyethylene resin
as a cleaning resin until the weld line of the resulting
parisons where color exchange was most difficult was
not colored to obtain the total quantity of the cleaning
resin required therefor.
Further, parisons were molded with the ABS resin
under the same conditions, followed by molding the
parisons with the colorless polyethylene resin as
a cleaning resin without using the cleaning resin
compositions until the weld line of the resulting
parisons was not colored, to obtain the total quantity
of the cleaning resin required therefor. These results
are collectively shown in Table 3.
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Table 3
Colored Cleaning resin Quantity of cleaning
resin composition resin used
Tempera- Case of use Case of non-
Kind ture at of the com- use of the
its use position composition
of Ex. 3 260C 3.3 30-5
that of 1. 2 9
Black Ex. 4
ABS resin that of " 10 0 "
Comp. ex. 1
that of 11.8
Comp. ex. 3
that of 230C 5.8 60.0
that of ~ 6 5
Ex. 2
Black that of " 17 4 "
ABS resin Comp. ex. 1
Comp. ex. 2 18.0 "
that of ~ 23.0
Comp. ex. 3
that of 230C 5.7 57.5
that of " 5 5 ..
Ex. 4
Black that of " 17 7 "
HDPE resin Comp. ex. 2
1) that of 20.4
Comp. ex. 3
that of .. 22 8
Comp. ex. 4
Ex. 4 200C 7.0 70.5
that of ..
Black that of " 18 0 "
ABS resin Comp. ex. 1
that of .. 20.0
Comp. ex. 2
Comp. ex. 3 26.0
- 1) High density polyethylene
1 336487
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According to the present invention, as seen from
Tables 2 and 3, when the respective cleaning resin
compositions shown in Examples 1-5 are used each in
a small quantity, it is possible to far reduce the
quantities of the cleaning resin used as compared
with those shown in Comparative example 1-4.
and display a notably excellent cleaning effect.
The cleaning resin composition of the present
invention has a notably excellent cleaning effect at
the time of color exchange of the preceding colored
resin in various molding machines and also at the time
of cleaning for exchange of the preceding resin.
Namely, by using the cleaning resin composition
of the present invention in a small quantity or by
using the composition in a small quantity together
with a cleaning resin, it is possible to far reduce
the quantity of cleaning resins consumed and also
notably shorten the cleaning period of time, as
compared with the case where the inside of molding
machines has so far been cleaned by exchange with
cleaning resins each color exchange.
Such effect will be illustrated by cleaning of
the inside of an injection molding machine. As seen
from comparison of use of the cleaning resin composi-
tion of the present invention with use of cleaning
. - 17 - 1336487
resins alone, it is possible to reduce the quantity
of the cleaning resins required down to about /5 ~ /10
and also to shorten the cleaning period of time down
to about /5 ~ /10
Further, the cleaning resin composition of the
present invention displays a notably excellent effect
at the time of color exchange and also at the time of
resin exchange even in the case where engineering
plastics such as modified PPO resin, polyphenylene
sulfide resin, etc. as the preceding resin are molded
at high temperatures.
