FR2495181A1 - IMPROVED BLOW VULCANIZATION OF PROCESSED ENVELOPES OR PNEUMATIC BANDAGES, TREATMENT COMPOSITION THEREFOR, AND METHOD OF VULCANIZING ENVELOPES - Google Patents

Abstract

Composition for the lubrication of tire vulcanization bladders. It comprises clay, a polydimethylsiloxane in an appropriate viscosity range, poly (ethylene glycol and / or propylene glycol) having the desired molecular weight and a surfactant. The invention also relates to the preparation of this composition, to a process for treating tire vulcanization bladders and to a process for molding a rubber tire using this coated vulcanization bladder.

Description

C,; D; C

  The present invention relates to d.r.

  lubricant for vulcanizing bladders of pneumatic wrappings or tires, vulcanization bladders of enve-

  externally coated lugs of these lubricating compositions.

  and a process for vulcanizing the envelopes used? a bladder thus treated. "Usually, rubber tires pori: vehicles are made by molding and vulcanizing a"

  green envelope, that is to say not vulcanized and unformed, '.

  in a molding press in which the green shell is pressed out against the surface of a mold by means of an expandable bladder by an internal fluid. By this method the green shell is shaped against the surface of the mold, which defines the design of the tread of the flight, eg, and the shape of the flanks. The casing is cured vulcanized. In general, the bladder is dilated by the pressure supplied by a fluid such as a hot gas. hot water e or steam, which also participates in heat transfer for vulcanization. The envelope is then allowed to cool a little in the mold, sometimes with the addition of cold water or cooler into the bladder. Then the mold is opened, the bladder is deflated by releasing the pressure of its internal fluid and the envelope is removed from the mold and envelopes. This use of tire vulcanization bladders is well known to those skilled in the art. It is known that a significant movement occurs between the outer bladder contact surface and the bladder. the inner surface of the envelope during the phase of di ?, tation of the bladder before the complete vulcanization of 1'in! #

  Loppe. Similarly, there is also a relative movement considered -

  between the external contact surface of the bladder and the vulcanized inner surface of the casing after molding: -: vulcanization of the casing during deflation and 4 ':! extraction of the bladder from the envelope. t A ,,,, ç.4.19 i

24951?

  Unless adequate lubrication is provided between the bladder and the inner surface of the bladder, the bladder

  generally tends to curl, which leads to a

  forming the envelope in the mold and also excessive wear and grinding of the surface of the bladder itself.

  The surface of the bladder also tends to stick to the s = r-

  inside of the envelope after vulcanisation of the envelope.

  loppe and during the course of the vulcanization cycle of

  the envelope corresponding to the deflation of the bladder. In-

  Air bubbles may be expressed between the surfaces of the bladder and the envelope, favoring the appearance of vulcanization defects of the envelopes due to

inadequate heat transfer.

  For this reason, pre-coating of the green or unvulcanized casing with a lubricant is usually done to lubricate the outer surface of the bladder and the inner surface of the casing during the shaping and molding operation of the casing. 'envelope. The lubricant is sometimes referred to as the "lining cement." Usually, the inner surface of the green shell,

  which is usually a mixture of rubber gum is sim-

  spray-coated in a spray booth.

  closed, ventilated, a lubricant that can for example be based on silicone polymer. Other additives may

  also be commonly used in the composition of lubricants

  such as mica, polymeric polyols, ethers

  celluloses, clays such as bentonite, etc.

  Some lubricants are solvent-based, others are

  water. Aqueous solutions of soaps are often used.

  Many lubricant compositions have been described in

  the technique for this application.

  However, the usual practice of

  spray-coating the inner surface of a raw envelope of a lubricant composition can lead to an operation

  which requires a relatively large workforce, which.

  can significantly increase the cost of manufacture. i of the envelope. The envelope must be transported to the cabin

  spray and be reported, and should be left i.

  sprayed lubricant coating time to dry. It is therefore desirable to have an improved lubrication system with regard to its composition and use.

  for molding or shaping and vulcanising the enve-

raw loppes ..:

  According to the invention, there is provided a comn-

  lubricant position which results from the mixing of: (A) from about 10 to about 40, preferably about 35 parts by weight of a bentonite having a particle size of from about 0.149 to about 0.03, preferably between about 0.074 and about 0.037 my; Ej

  (B) about 15 to about 45, preferably about.

  to about 35 parts by weight of a polydimethylsiloxane.

  characterized in that it has a viscosity of between about.

  000 and about 120,000, preferably between about 50,000 -:

  and about 70,000 centistokes at 25 ° C.

  (C) about 12 to about 36, preferably about 30 parts by weight of a poly (ethylene glycol and / or propylene glycol), characterized in that it has a molecular weight D of about 1500 to about 2500 preferably from about 1800 to about 2200; (D) about 10 to about 25, preferably about

  to about 20 parts by weight of surfactants for.

  this polydimethylsiloxane and this poly (alkylene glycol); and (E) if desired, about 4 to about 12 parts.

by weight of a stabilizer ..

  The composition intended for application on the surface

  bladder face is an emulsion or an aqueous dispersion.

  compositions. For example, the composition for this ....

  application also contains (F) about 500 & about 1500, of.

  Preferably, about 600 to about 800 parts by weight of water is evaporated after application to the bladder. Surely more water can be used, although further dilution of the composition will reduce the effectiveness of its application. It should be noted that the polydimethylsiloxane may have hydroxyl end groups as an ingredient

  (precursor) for the preparation of the composition.

  The invention further provides a rubber bladder

  rubber for vulcanizing expandable envelopes, coated with such a composition (especially after removal of water). In practice, bladder rubber is generally butyl rubber or butyl rubber (copolymer of isoprene and isobutylene). The term "butyl type" refers to various modified basic butyl rubbers, such as halogen-substituted butyl rubbers, such as

  chlorobutyl rubber and bromobutyl rubber.

  The invention further relates to a method of eradicating

  pneumatic or semi-pneumatic rubber casing

  In which case a green envelope is placed in an envelope mold. The expandable bladder coated with the invention is disposed therein, the mold is closed and the bladder is expanded by applying a pressure of internal hot fluid to apply the same. casing outwards against the surface of the mold so as to shape and vulcanize the casing, after which the mold is opened, the bladder is deflated and the shaped and vulcanized casing is removed. The bladder is usually

  connected to an inner part of the envelope mold itself.

  In a more detailed manner, this method of molding pneumatic or semi-pneumatic envelopes comprises the following operations: (A) procuring or manufacturing a raw envelope with

  elements that will form its external tread intended to

  born to come into contact with the ground, two inextensible heels: 4; ij:., i. {,: If 9: ':; i:' j. 2495181.r separated, flanks extending radially outward from the heels to join the tread, a support carcass comprising reinforcement elements and aae: rubber compound inner surface; (B) introduce the green envelope into a press.

  molds for envelopes and dispose of a vulcanizate bladder, "o-

  envelopes coated with the invention within the scope of the invention.

  Raw lopper, the bladder being attached to an inner portion of the envelope press. (C) close the envelope mold and expand the Vee: 1 sie of vulcanizing the envelopes coated, by means of an internally heated fluid, outwardly, against the inner surface 14, of the gum mixture of the envelope , to press the e-M i veloppe out to hot and under pressure for way.

to vulcanize the envelope; i.

  (D) open the envelope mold, deflate the window and remove the vulcanized casing, generally shaped. The expression "pneumatic envelope" means - :! envelopes whose correct functioning, when they are. ' mounted on a rim, rests on an internal fluid, such as; i of the air under pressure in their envelope cavity, and ex ;.

  pressure "semi-pneumatic envelope" relates to envelopes.

  that contain an internal fluid, such as air, in! ei '"cavity, but whose proper functioning, when s8:

  mounted on a rim, does not depend completely on its proximity.

  if we. C4 In the practice of the invention, the emulsion or dis ;:

  aqueous persion of the lubricant composition can be ob :.

  conveniently maintained by the process of

  (A) mix under high shear about 10 to.

  about 40, preferably about 25 to about 35 e, o -....

  weight of a bentonite having an included particle size :.

  between about 0.149 and about 0.03 mm, preferably between: %, about 0.074 and about 0.037 mm, with about 500 to about 1500, preferably about 600, about 800 parts by weight of water at a temperature of about 20 to about C, preferably the water being preheated at a temperature of about 50 to about 85 C, until the mixture appears to be thickened;

  (B) mix with the previous mixture about 15 to

  45, preferably about 25 to about 35 parts by weight of a polydimethylsiloxane characterized in that it has a viscosity of from about 40,000 to about 120,000,

  preferably between about 50,000 and about 70,000 centisto-

  at 25 ° C, about 12 to about 36, preferably about 30 parts by weight poly (ethylene glycol and / or

  propylene glycol), characterized in that it has a molecular weight

  from about 1500 to about 2500, preferably

  this between about 1800 and about 2200, and a surfactant

  tif, in a proportion which is preferably from about 4 to about 10 parts by weight, for this polydimethylsiloxane and poly (alkyl) glycol; (C) mixing, if desired, with the above mixture about 2 to about 10 parts by weight of additional surfactant to reduce friction between bladder and shell; (D) mix if desired to the previous blend

  from about 2 to about 8 parts by weight of an inhibitor of

  erosion; (E) mixing, if desired, with the above mixture about 0.2 to about 1.0 parts by weight of an antifoam agent; (F) mix if desired to the previous blend

  about 2 to about 10 parts by weight of stabilizer.

  It is clear that various antifoam agents

  well known and various stabilizers may be used

  in the practice of the invention, which are well known in the art.

Specialists.

2495181 "

  The aqueous emulsion or dispersion is simply applied, for example by spraying, onto the bladder and dried by evaporation at a temperature which will be, for example:

  from about 20 ° C to about 110 ° C.

  In the clothing, it is preferred that the bladder be about 80 to about 150% of its expanded state for the vulcanization of the envenom (not deflated or collapsed), although this is not to be considered as necessary and that bladders were

  successfully coated in a somewhat deflated condition.

  In the practice of the invention, it has been observed that when using the coating indicated on a bladder of

  rubber, it is possible to mold with this bladder

  9 envelopes (6 to 9 cycles of vulcanization of envelopes

  pes) until there is excessive adhesion between the outer bladder contact surface and the inner surface.

  envelope, manifesting itself in an excessive tendency.

  sive to gluing when deflating the bladder after vulca- ,:

the envelope.

  This number of cycles of vulcanization is considered.

  compares favorably with that obtained with composi-

  previous coating which are familiar to the De-

  manderesse. An important element of the lubricant composition is obviously the presence of the polydimethylsiloxane fluid;

  However, it should be noted that this coating turned out a -

  little greasy in the absence of bentonite, which tends not only, OQ to fight against the greasy appearance of the surface of the bladder:

  coated, but also allows, apparently in a wide me-f.

  sure, trapped air to escape from the surface. The -

  von or optional additional surfactant can be advantageous because it can apparently increase the slip

between the bladder and the envelope.

  The optional antifoam agent may be

  an aqueous emulsion of polydimethylsiloxane which has the advantage

  prevent or inhibit the formation of foam when

  lange. The following non-limiting examples are given in

  As an illustration of the invention. Unless otherwise indicated

  The parts and percentages are all by weight.

EXAMPLE 1

  A lubricant composition is prepared according to

  the formula in Table 1 below.

TABLE 1

  Material Parts Bentonite clay (0.044 m) 12.5 Water 759 Polydimethylsiloxane and polyglycol1 62.5 Surfactant2 6.25 Corrosion inhibitor (sodium benzoate) 5 Anti-foam 0.33 Stabilizer 6.25

  ldescribed as a viscous polydimethyl-

  siloxane having a viscosity of about 60,000 centistokes in

  a mixture of about 31.3 parts of this polydimethyl

  siloxane, about 25 parts of a polypropylene glycol having a molecular weight of about 2,000 and about 6 parts of a

surfactant for it. -

  2Sodium soap of a vegetable oil, considered

optional horn.

  The aqueous emulsion or dispersion is prepared according to the following procedure: (A) Heat the water to a temperature of about 60 ° C

  and add the clay. Mix at 2500 rpm in a mixture

  Cowles for approximately 2 to 5 minutes, during which time

  the appearance of the mixture shows that it has thickened.

  (B) Add the organopolysiloxane fluid mixture

  xane under a high shear at 2500 rpm to make a

249 518 ;!

  aqueous emulsion. (C) Add the additional surfactant. (1) Add the corrosion inhibitor to protect [

the application apparatus.

(E) Add silicone antifoam.

(F) Add the stabilizer.

  The mixture is sprayed onto the outer face of the rubber bladder for vulcanization of the envelopes in its expanded state. The mixture is allowed to dry at about 65 ° C. The x-coating is again applied after about 4 cycles of vulcanization of the envelopes with a maximum of about 6 hours between the coating applications. The coating is dried for about 1 minute

  the hot surface (65 C) of the bladder to form a rev,!.

  The bladder itself is a butyl-type bladder having a generally toroidal shape with an overall diameter in the expanded state of about 990 mm and a diameter of about 10 mils. .t tubular about 250 minutes. Its surface has been pre-treated with a hydrocarbon solvent and then dried to remove

surface oils etc ...

  A raw shell & radial carcass is manufactured

of dimension 11 R 22.5.

  We place the envelope in a press & molds

  envelopes and we introduce into the envelope the bladder rev -

  attached to the mold. The mold is closed and the bladder is expanded with a steam medium at a temperature of about 190 ° C. in order to press against the inner surface of the casing and the casing is pressed out against the surface of the outer mold. so that the envelope is shaped in the desired manner and vulcanized. "

  We then open the mold, deflate the bladder-

  the envelope is removed. By doing so, it is observed that: ## EQU1 ## can mold about 6 to about 9 envelopes with the bladder in a period of about 8 hours (vulcanization cycles)

  before it is necessary to re-seal the bladder of the

lubricant position.

  In general, it is considered necessary to reseal when the bladder sticks excessively to the inner surface of the prevulcanized envelope when the dilated bladder

  is deflated or deflated after the vulcanization operation.

  It is recognized that the inner surface of the envelope is typically a gum mixture which may be various rubbers or mixtures thereof, such as natural rubber, cis-1,4-polyisoprene, cis-1,4- polybutadiene, butadiene-styrene copolymers, butyl rubber, halobutyl rubbers such as chlorobutyl and bromobutyl and EPDM (ethylene-propylene terpolymer-small amount of diene). We have chosen here as an example the manufacture of a

  radial carcass envelope. Although the invention may

  can be considered more adaptable to the production of

  radial-ply carcasses than casings with diagonal carcass

  because the bladders usually have to expand further

  during the vulcanization cycle of a battery envelope.

  diagonal case, thus stretching the surface coating of the bladder, it is considered that, in general, the invention

  is easily adaptable to the manufacture of card envelopes.

diagonal breakage.

  It is important to note that the envelope of this

  example was manufactured by dilating the directly coated bladder.

  against the internal surface of the gum mixture of the

  loppe to press the envelope outward under hot and pressure to shape and vulcanize the envelope. So,

  the coated bladder actually made it possible

  without the application of a coating of lubricant or

  lining cement, on the inner side of the raw envelope.

2495181 ..:

  This is considered important since it has been demonstrated that the coated bladder of the invention allows adequate lubrication for a series of successive cycles of vulcanization of the envelopes under heat and pressure conditions. : ': -dilatation and contraction, without prior application

  conventional cement lining of envelopes or

  brifiant on the inner face of 1 envelope. One can reasona ,.

  consider that this will result in savings.

  * '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' '' "

  precoating lubricant on the inner face of the envelope C ?.

-: -? F.,

  In combination with the coated bladder, it is considered important that this example demonstrates that this is not necessary for a series of successive cycles of vulcanization of L envelopes under heat and peso conditions. and contraction, without the prior pastel application: [::: 2: conventional of a lining cement envelopes or a lu-: L 7; brifiant on the inside of the envelope. It may reasonably be considered that this will permit savings in labor and material costs in the manufacture of X-rays. ',: i' ::: 'h% fi,

R E V E N D I C AT IO N S

  1 - Lubricating composition, characterized in that

that she understands: -

  (A) about 10 to about 40 parts by weight of a bentonite having a particle size of about 0.149 to about 0.03 mm; (B) from about 15 to about 45 parts by weight of a polydimethylsiloxane. having a viscosity of about 40,000 to

  about 120,000 centistokes at 25 C.

  (C) about 12 to about 36 parts by weight of poly (ethylene glycol and / or propylene glycol) characterized in that it has a molecular weight of from about 1500 to about 2500;

  (D) about 10 to about 25 parts by weight of

  gent (s) surfactants for polydimethylsiloxanes and poly (alkylene glycol) (E) if desired, about 4 to about 12 parts

by weight of a stabilizer.

  2 - lubricating composition according to claim 1, characterized in that the polydimethylsiloxane of (B) has

hydroxyl end groups.

  3 - Lubricating composition according to claim

  1, characterized in that it is an aqueous emulsion containing

  from about 500 to about 1500 parts of water by weight.

  4 - Lubricating composition according to claim

  2, characterized in that it is an aqueous emulsion containing

  from about 500 to about 1500 parts of water by weight.

  Vulcanizing bladder for envelopes or wraps made of vulcanized, expandable rubber, characterized in that

  that she wears a coating of the composition according to the

  claim 1 on its exposed outer face.

  6 - Vulcanization bladder for rubber casings

  vulcanized vulcanized rubber of the butyl type, expandable, toroidal shaped, for pneumatic or semi-pneumatic tires, characterized 249518 1t 13; in that it bears on its outer face a coating of the

  composition according to claim 2.

  7 - Process for the Preparation of the Composition Next to

  any of claims 1 and 2, characterized in that

  that: (A) about 10 to about 40 parts by weight of a clay are mixed under high shear conditions; bentonite having a particle size of from about 0.149 to about 0.03 mm with about 500 to about 1500 parts of water at a temperature of about 20 ° C and about 90 ° C until the mixture appears to have thickened (B) mixing with the mixture Previously, while maintaining the mixture at a temperature of about 20 ° C, about 10 to about 45 parts by weight of a polyethylsiloxane characterized in that it has a viscosity of around 120 000 centistokes at 25 C, about 12

  36 parts by weight of poly (ethylene glycol and / or pri.

  glycol), characterized in that it has a molecular weight of from about 1500 to about 2500, and a surfactant for polydimethylsiloxane and polyalkylene glycol: coli;

  (C) optionally mixed with the preceding mixture;

  about 2 to about 10 parts by weight of an additional surfactant; (D) optionally mixing with the preceding mixture: about 2 to about 8 parts by weight of an erosion inhibitor; (E) from about 0.2 to about 1 part by weight of antifoam agent is mixed with the preceeding mixture:%

  (F) optionally mixed with the preceding mixture:

  about 2 to about 10 parts by weight of stabilizer. e-: 8 - Process for treating a pneumatic casing vulcanized rubber vulvicization bladder, table diode, of toroidal shape, for a pneumatic casing o;

  semi-pneumatic system, characterized in that the outer face is

  exposed dullness of the bladder, at about 80 to about 150% of

  its dilated state of vulcanization of the tires, the com-

  position according to claim 3 and in that the composition is dried. 9 - Process according to claim 8, characterized

  in that the bladder is made of butyl rubber.

  Process according to claim 9, characterized

  in that the polydimethylsiloxane has terminal groups

hydroxyl.

  11 - Method of molding a pneumatic or semi-pneumatic envelope, characterized in that (A) is obtained or manufactured a green envelope comprising elements intended to form its outer tread which will be in contact with the ground, two separate heels

  inextensible, flanks radially outwardly

  and from the heels to join the tread, a support carcass having reinforcing members, and an inner face of a rubber gum mixture; (B) the green envelope is introduced into a press

  envelopes and a vulcanis bladder is available.

  coating the coated shells according to claim 5 within the green envelope, the bladder being attached to an inner portion of the wrapper; (C) the envelope mold is closed and the bladder coated with vulcanization of the envelopes is dilated by means of a

  heated internal fluid, outwards against the inner surface

  dull gum blending of the envelope to squeeze the envelope

  loppe outward under hot and pressure, so as to shape and vulcanize the envelope; and (D) open the envelope mold, deflate the

  bladder and the vulcanized casing having a generally

toroldale.

  12 - Process according to claim 11, characterized

  In that the bladder is made of butyl rubber of the type b.

tyle. -

  13 - Process according to claim 12, characterized

  in that the polydimethylsiloxane of the

  coating has hydroxyl end groups.

  14 - Process according to any one of the claims

  12 and 13, characterized in that the bladder is expanded, said coating being pressed directly against the surface

internal envelope.

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