Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~060595
This invention relates to a method of releasing
inflatable bags from freshly molded tires and to a
powdery bag lubricant ~sed in such method.
One of the h~gh volume production industries
in the world today is the manufacturing of tires.
Because of the high production rate and because
of the unique configuration of the product being molded,
there arises several problems which do not arise in the
molding of ordinary items of commerce.
One such problem is the formation of the
internal configuration of the tire. This has been
resolved by utilizing a rubber "bag" or bladder. This
"bag" , in con~unction with steel molds, allows the
formation of the tire within the steel mold by a process
which inflates the bag by hot water, steam or air, on
the inner face of the raw unvulcanized rubber while the
unvulcanlzed rubber is being pressed in the steel mold.
When the tire is vulcanized, the pressure on the bag
is reduced and the bag collapses, thus allowing the
bag to be withdrawn from the narrow constricture formed
by the internal edges of the now vulcanized tire.
One further problem, however, continues to ;~
plague tire manufacturers and that is the problem of
getting release of the inflatable bag from the interior
surface of the tire.
~ It is true that release of the bag can be
i achieved by shear force but this tends to distort the
inner surface of the tire even to the point of causing
small ruptures in the inner surface of the bire. Moreover,
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æuch undesirable forced release slows down the process
of manufacturing tires. -~
Thus, attempts have been made to cause a much
easier, simple and fast release of the bag from the tire. ;
Such attempts have been directed to the use
of organic release agents, liquid polysiloxane release
agents, solvent-based polysiloxane release agents and
eventually the use o~ aqueous emulsions of polysiloxane
release agents.
Such compositions are not without their
disadvantages however. Organic release agents tend to
give fewer releases and, thus, their use requires large
volumeæ of the release material and, hence, additonal
cost to the manufacturer.
Liquid polysiloxanes, i.e., neat dimethylpoly-
siloxanes, even though they give more releases per
application, suffer from the fact that the releases are
uneven and the polydimethylsiloxanes are difficult to
I apply.
'~ 20 In order to overcome the difficulty of applying
the neat polydimethylsiloxanes, the users turned to
solvent-based systems. Such systems, however, are defective
in terms of the risk of explosion, risk of fire and air ,
pollution. In addition, there ls the ever present danger
of sub~ectlng employees to the hazards of volatile solvents.
To overcome the above difflculties, manufacturers
turned to emulsion-based polysiloxane systems. These
types of materials overcome the ma~ority of the problems
associated with the methods heretofore employed.
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There are several problems, however, that still
abide when one contemplates the use of emulsion-based
materials. Specifically, the presence of the water leads
to the shipment of large volumes of materials since
emulsions generally are constituted of from 60 to 90
weight percent of water. Secondly, the emulsion-based
materials are inherently unstable when stored for some
periods of time. Moreover, there have been difflculties
in mixing the mica or talc powders into these systems.
Finally, long storage leads to the propagation of micro-
organisms and eventually putrefaction of the emulsifiers -
used to suspend the talc or mica.
Such emulsions have been described, for example,
ln Canadian Patents No. 866,659, 962,390 and U.S. Patent
No. 3,905,823.
Because of the above named defects in the prior
art systems, it was necessary to develop a new material
which would have superior or at least comparable release
to the~above named systems while having advantages not
found in the prior art materials.
Thus, it is an ob~ective of the instant
invention to provide a method of causing release of an
inflated bag from a moldçd tire.
It is another ob~ective of this invention to
provide a composition which gives superior or equal
release of the inflatable bag from the vulcanized tire.
It is a further ob;ective of this invention
to provide a composition which can be stored indefinitely
It is yet another ob~ect of this invention to
provide a composition whlch can bç shipped in larger
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volumes at a lower cost due to the absence of unnecessary
large volumes of water
Thus, in accordance with this invention, it has
been found that a powdery bag lubricant, which has equal
or superior release of an inflatable bag used during tire
molding, which can be stored indefinitely and which
eliminates the problem of shipping large volumes of
materials, can be obtained by mixing
(A) 3 to 27 parts by weight of polydiorgano- ;~
siloxane having a viscosity of at least 100 cs. at 25C.,
(B) 0.5 to 20 parts by weight of at least one
dispersant-emulsifier selected from the group consisting of
(i) polyoxyalkylene glycol esters of higher
fatty acids, polyoxyalkylene glycol ethers of higher
alcohols, polyoxyalkylene glycol ethers of polyhydric
alcohols, and polyoxyalkylene glycol ethers of alkyl phenols,
(ii) alkylbenzene-sulfonic acld salts or salts
of higher alcohol esters of sulfuric acid,
(iii) polyvinyl alcohol, methyl cellulose, - :
carboxymethyl cellulose and carboxyethyl cellulose, and
(iv) lecithin, and
(C) 40 to 97 parts by weight of a parting
agent selected from a group consisting of
(1) mica, and
(2) talc or a mixture of (1) and (2) wherein ;~
each has a particle size of 100 to 1000 mesh.
The diorganopolysiloxanes, component (A), used
in the present invention, can be, for example, dialkyl-
polysiloxanes such as a polydimethylsiloxane, polydlethyl-
siloxane, polymethylisopropylsiloxane and polymethyldodecyl-
siloxane; polyalkylphenylsiloxanes such as polymethylphenyl-
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siloxane, polydimethyl-polymethylphenylsiloxane copolymers, and
polydimethyldiphenylsiloxane copolymers, polyalkylaralkyl-
siloxanes such as polymethylphenylethylsiloxane and
polymethylphenylpropylsiloxane and halosubstituted
polyalkylsiloxanes such as poly-3,3,3-trifluoropropylmethyl-
siloxane. The siloxanes are essentially linear but some
branched polysiloxanes may be used. As much as up to 5
mole percent of the total siloxane in the composition can
be non-linear.
The siloxanes can be endblocked with either
hydroxy groups or triorganosilyl groups. Examples of
triorganosilyl groups are Me3SiO,/2, Me2(CH2=CH)SiOl/2,
Me(CH2=CH)phenylSiO~/2 and Mez(phenyl)SiOl/2.
The polydiorganosiloxanes are us~d in the
composition at 3 to 27 parts by welght. If this amount
is exceeded, the free flowability and dispersibility
in water is lost. The net effect is that caking is
caused upon storage of the product. The lower limit
is 3 parts by weight and if less than this amount is used,
good lubricity and separation of the inflatable bag is
lost.
Component (B) is a dispersant-emulsifier. ~
These materials can be (i) non-ionic surface active agents. ~ -
Examples of such materials are higher fatty acid esters
of polyalkylene glycol, for example, polyalkylene glycols
and lauric, myrlstic or palmitic acids. ~
They can also be polyalkylene glycol ethers -
such as polyalkylene ethers of octyl, lauryl, cetyl or
oleyl alcohols.
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The ethers can also be prepared from polyhydric
alcohols such as ethylene glycol, propylene glycol,
glycerin, sorbitol or sorbitan.
When the ethers are prepared from polyalkylene
~lycol and alkyl phenols, there can be used octylphenol,
dodecylphenol and nonylphenol.
The polyalkylene glycols for use in the above
can be polyethylene glycols, polypropylene glycols and
copolymers of ethylene and propylene glycols. The degree
Of polymerization in the polyalkylene glycol ls not
particularly critical, ranging from 1 to 50. A preferred
range is 5 to 30.
Component (B)(ii) can be anionic ~urface active
agents. There can be used higher alcohol sulfuric acid
ester salts such as the potassium and sodium salts
of a sulfuric acid ester of octyl alcohol, potassium and
sodium salts of a sulfuric acid ester of lauryl alcohol,
sodium and potassium salts of a sulfuric acid ester of
cetyl alcohol and sodium and potassium salts of a sulfuric
acid ester of oleyl alcohol.
Examples of the alkyl benzene-sulfonic acid
salts are sodium octylbenzene-sulfonate, sodium dodecyl-
benzene-sulfonate and sodium nonylbenzene-sulfonate.
Component (B)(iii) is a thickening agent as well
as a dispersant-emulsifier and can be polyvinyl alcohol,
methyl celluloseS carboxymethylcellulose or carboxyethyl-
cellulose. These materials are synthetic pastes and when
the composition of the present invention is dispersed or
dissolved in water, these materials are emulsion stabllizers
and sedimentation preventing agents for the mica and talc.
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60595
Component (B)(iv), lecithin, is a natural
emulsifier present in albumin or soybeans.
Component (C) is a parting agent and can be
either mica or talc or a mixture of mica and talc. The
parting agents should have a particle size of 100 to 1000
mesh and should be used in quantities ranging from 40 to
97 parts by weight.
The above components can be mixed by ordinary
means available to those skilled in the art. One preferred
method of combining the ingredients comprises stirring at
least one dispersant-emulsifier (B) with a diorganopoly-
siloxane (A) and thereafter adding the mica or talc (C).
After the components are thoroughly mixed together, they
are then ready for use or can be shipped or stored. The
resulting material is a powdery, flowable parting composition.
The powdery, flowable parting composition is
then gradually added to water under agitation and is then
ready for use in molding tires. At times, it may be
desirable to add a small amount of solvent and, if
necessary, isopropyl alcohol in water or gasoline
containing a small amount of water may be used.
The inventive composition may optionally
contain common ingredients known to those skilled in the
art such as anti-oxidation agents such as magnesium
stearate, sodium nitrite, amine salts, phosphates or the
like; antiseptic or anti-mildew agents for controlling
mildews such as formalin, dehydroacetic acid, sodium
dehydroacetate, benzoic acid, sodium benzoate, sorbic
acid, sodium sorbate or the like. Also, there can be
included pigments or dyes.
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The present invention will now be described in
-~ detail by reference to the following examples.
Example 1
- 10 parts by weight of dimethylpolysiloxane
(both the terminals being blocked with trimethylsilyl
groups) having a viscosity of 60000 cs. as measured at
25C. was added under agitation to a mixture of 2 parts
by weight of methyl cellulose powder and 5 parts by weight
of polyethylene glycol having a molecular weight of 500.
Then 83 parts by weight of mica powder having a size of
200 mesh was gradually added to the above mixture and the
resulting mixture was agitated for about 30 minutes.
The so formed parting compositlon for molding
tires was a powder having a free flowability, which was
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;~ not degraded at all even after it had been stored at
, room temperature for one year.
"~i 50 parts by weight of this powdery parting
;; composition was gradually added into a vessel in which
50 parts by weight of water had been charged and the
mixture was sufficiently agitated.
The so obtained aqueous tire parting composition
could be atomized. When it was sprayed on a raw rubber
sheet and dried and the raw rubber sheet was rubbed with
;.
another raw rubber sheet, a good lubricating property
; was observed.
When two of so sprayed rubber sheets were piled
; together and pressed by a pressing machine, it was found
that the parting property was very good.
When the so formed aqueous parting composition
~ 30 was placed in a glass bottle and allowed to stand overnight,
;~ no phase separation took place.
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Example 2
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5 parts by weight of dimethylpolysiloxane (both the
terminals being blocked with trimethylsilyl groups) having a
viscosity of 350 cs. as measured at 25C. was added to a
mixture of 0.5 part by weight of a polyethylene glycol ether
of nonylphenol (the degree of polymerization in polyethylene
glycol being 10), 3 parts by weight of soybean lecithin and 0.2
part by weight of carboxymethyl cellulose and the mixture was
agitated suficiently. Then 75.3 parts by weight of mica having
a size of 1000 mesh and 16 parts by weight of talc having a
size of 200 mesh were added to the above mixture and the
resulting mixture was agitated sufLiciently.
`~ The so prepared parting composition for molding tires was
powder having a good free flowability which was not reduced at
all even after it had been stored at room temperature for one
year.
60 parts by weight of this powdery parting composition
was gradually added under agitation into a vessel in which 40
parts by weight of water had been placed to thereby form a
dispersion. The viscosity of the so obtained aqueous parting
composition ~as 2200 cp. and it could be atomized in a very
good condition and had very good parting and lubricating ~ ~ -
properties. When this aqueous parting composition was charged
in a graduated separation tube and subjected to centrifugal
separation at 2000 r.p.m. for 5 minutes, mica or talc was not
sedimented or solidified.
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Example 3
15 parts by weight of a polysiloxane havlng a
viscosity of 1000 cs. as measured at 25C. and represented
by the following formula: -
CH3 CH3
(CH3)3SiO-(SiO)X-(SiO)y~Si(CH3)3
C2H~ CH2
CHCH3
C6H~
; 10 wherein the mole ratio of x and y is 4:6, was sufficiently
agitated and mixed with 1.0 part by weight of sodium
lauryl sulfate, 10 parts by weight of polyethylene glycol
,~
and 0.5 part by weight of carboxymethyl cellulose. Then ;
36.8 parts by weight of mica having a size of 400 mesh
and 36.7 parts by weight of talc having a size of 200 mesh
were mixed sufficiently with the above mixture under
agitation. The parting composition obtained for molding -
' tires was a powder having a good free flowability.
Then 50 parts by weight of this powdery parting
composition was mixed with 50 parts by weight of water to
? obtain an aqueous parting composition having good parting
, and lubricating properties.
After this powdery parting composition had been
stored at room temperature for 6 months~ 50 parts by weight
of the parting composition was mixed with 50 parts by
weight of water. The resulting aqueous parting composition -
was quite comparable to the above aqueous parting composition
', prepared by using the as-prepared powdery parting composition
3 with respect to the parting and lubricating properties,
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Exa~ple 4
10 parts by weight of dimethylpolysiloxane (both the
terminals being blocked with trimethylsilyl groupsl having a
viscosity of 100 cs. as measured at 25C was sufficiently
: mixed and agitated with 10 parts by weight of a polyalkylene
glycol glycerin ether represented by the following formula: .
' ' .
CH8(OC2H4](OC3H6)OH
CH(OC2H4)(OC3H6)OH :
CH3(OC2H4)(OC3H6)OH
and 80 parts by weight of mica having a size of 100 mesh was
gradually added to the above mixture under agitation, to form
a powdery tire-molding parting composition having a good free
flowability. Then 50 parts by weight of this powdery parting
composition was mixed and agitated with 50 parts by weight of :;
water to obtain an aqueous parting composition having good
parting and lubricating properties. : ~.
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