CA1060595A

CA1060595A - Parting agent in powder form

Info

Publication number: CA1060595A
Application number: CA247,226A
Authority: CA
Inventors: Isao Ona; Terumi Mie
Original assignee: Toray Silicone Co Ltd
Current assignee: DuPont Toray Specialty Materials KK
Priority date: 1975-03-07
Filing date: 1976-03-05
Publication date: 1979-08-14
Also published as: FR2302848B1; JPS6021044B2; DE2609157A1; FR2302848A1; GB1539762A; JPS51103180A

Abstract

Abstract of the Disclosure A powdery bag composition is disclosed which allows release of an inflatable bag from a vulcanized tire and which consists of a polydiorganosiloxane, a dispersant- mulsifier and a parting agent such as mica or talc. The powdery bag composition is dispersible in water for convenience in using the composition.

Description

~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When the tire is vulcanized, the pressure on the bag is reduced and the bag collapses, thus allowing the bag to be withdrawn from the narrow constricture formed by the internal edges of the now vulcanized tire.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, 1~6~595 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 ;.. -, . ... . . . . .

~06059S -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-~60S95 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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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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10605~5 Example 2 . ..
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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~6~)595 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)3SiO-(SiO)X-(SiO)y~Si(CH3)3 C2H~ CH2 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, --1 0-- .

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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: .
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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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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A powdery parting composition for releasing inflatable bags from molded tires consisting essentially of (A) 3 to 27 parts by weight of a polydiorganosiloxane having a viscosity of at least 100 cs. at 25°C., (b) 0.5 to 20 parts by weight of at least one dispersant-emulsifier selected from the group consisting of (i) non-ionic surface active agents selected from a group consisting of polyoxyalkylene glycol esters of higher fatty acids, polyoxyalkylene glycol ethers of higher alcohols, polyoxyalkylene glycol ethers of polyhydric alcohols and polyoxyalkylene glycol ethers of alkylphenols, (ii) anionic surface active agents selected from the group consisting of salts of alkylbenzene sulfonic acids, and salts of higher alcohol esters of sulfuric acid, (iii) dispersant thickeners selected from a group consist-ing of polyvinyl alcohol, methyl cellulose, carboxymethyl-cellulose and carboxyethylcellulose, and (iv) lecithin, and (C) 40 to 97 parts by weight of a parting agent selected from a group consisting of (1) mica, (2) talc, and (3) a mixture of (1) and (2) wherein (1), (2) and (3) have an average particle size of 100 to 1000 mesh.

2. The powdery parting composition of claim 1 when it is dispersed in water.

3. The powdery parting composition of claim 1 wherein (A) is a trimethylsilyl endblocked polydimethylsiloxane having a viscosity of 60,000 cs. at 25°C., (B) is a mixture of 2 parts by weight of methyl cellulose powder and 5 parts by weight of a polyethylene glycol having a molecular weight of 500, and (C) is 200 mesh mica powder.

4. m e powdery parting composition of claim 1 wherein (A) is present in 10 parts by weight, (B) is present in 7 parts by weight and (C) is present in 83 parts by weight.

5. A method of releasing an inflatable bag from a vulcanized tire which method consists of treating the inflatable bag before it is inflated and before the tire is vulcanized with a powdery parting composition, which has been dispersed in water, consisting essentially of (A) 3 to 27 parts by weight of a polydiorganosiloxane having a viscosity of at least 100 cs. at 25°C., (B) 0.5 to 20 parts by weight of at least one dispersant-emulsifier selected from the group consisting of (i) non-ionic surface active agents selected from a group consisting of polyoxyalkylene glycol esters of higher fatty acids, polyoxyalkylene glycol ethers of higher alcohols, polyoxyalkylene glycol ethers of polyhydric alcohols and polyoxyalkylene glycol ethers of alkylphenols, (ii) anionic surface active agents selected from the group consisting of salts of alkylbenzene sulfonic acids and salts of higher alcohol esters of sulfuric acid, (iii) dispersant thickeners selected from a group consist-ing of polyvinyl alcohol, methyl cellulose, carboxymethyl-cellulose and carboxyethylcellulose, and (iv) lecithin, and (C) 40 to 97 parts by weight of a parting agent selected from a group consisting of (1) mica, (2) talc, and (3) a mixture of (1) and (2) wherein (1), (2) and (3) have an average particle size of 100 to 1000 mesh.