DE3146053A1 - LUBRICANTS, METHOD FOR THE PRODUCTION AND USE THEREOF - Google Patents

Description

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MÜLLER-BORii * · DEUFEIi · "SCHÖBT · HERTEL

PATENT LAWYERS EIJBOPBAN PATENT ATTOBNET8

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DR. WOLFGANG MÜLLER-BORE (PATENT ADVOCATE FROM 1927 - 1975) DR. PAUL DEUFEL. DIPL.-CHEM. DR. ALFRED SCHÖN. DIPL.-CHEM. WERNER HERTEL. DIPL.-PHYS.

G 3172

The Goodear Tire & Rubber Company,
Akron, Ohio 44316, USA

Lubricant, method of its
Manufacture and its use

MUNICH 86.S1EBERTSTR. 4 POB 860720 CABLE: MUEBOPAT TEL. (0 89) 474005 TELECOPIER XEROX 400 TELEX 5-24aS5

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description

The invention relates to lubricants for tire vulcanization blisters, Tire vulcanization bladders with an outer coating of such a lubricant and a Process for vulcanizing tires using a bladder coated in this way.

Conventionally, pneumatic rubber vehicle tires are used by deforming and vulcanizing a green or unvulcanized and unmolded tire in one Compression press, in which the green tire outwards against 'a Mold surface is pressed by means of a bubble expanded with an internal fluid. In this way the green tire is molded against the outer mold surface showing the tire tread pattern and configuration the side walls. The tire is vulcanized by exposure to heat. Generally will the bladder expands by internal pressure exerted by a fluid such as hot gas, hot water, and / or water vapor is generated, this fluid also taking part in the heat transfer for vulcanization. The tire is left then cool down a little in the mold, sometimes by adding cold or cooler water to the bladder is supported. The mold is then opened and the bladder collapsed by releasing the internal fluid pressure and the tire is removed from the tire mold. The use of such tire vulcanization bladders is known.

There is significant relative movement between the outer contacting surface of the bladder and the inner one Surface area of the tire during the expansion phase of the bladder before the tire is fully vulcanized. In a similar way There is considerable relative movement between the outer contacting surface of the bladder and the hardened one inner surface of the tire during the collapse and stripping of the bladder from the tire after

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this has been molded and vulcanized.

Unless there is adequate lubrication between the bladder and the inner surface of the tire, the bladder tends to wrinkle, causing undesirable deformation of the tire in shape, and also excessive abrasion and roughening of the bubble surface itself occur. Furthermore, the bubble surface on the inner surface of the tire after it has hardened during the collapse of the bladder in the course of the Adhere tire curing cycle. Furthermore, air bubbles can be trapped between the bubble and the tire surfaces and promote tire vulcanization defects as a result of insufficient heat transfer.

For this reason, it is common to apply a lubricant to the inner surface of the green or unvulcanized tire to be coated to provide lubrication between the outer bladder surface and the inner tire surface during to ensure the tire molding. Sometimes the lubricant is referred to as a liner. In conventional Way, the inner surface of the green tire, which is typically a rubber material, simply in a confined ventilated spray chamber coated by spraying with a lubricant which can for example be based on a silicone polymer. Other Additives can also be used in the lubricant in a conventional manner, such as mica, polymeric polyols, Cellulose ethers, clay such as bentonite clay, or the like. Some lubricants are solvent based and others are water based. Aqueous soap solutions are often used. Many lubricant formulations are known for these purposes.

The usual spray coating of the inner surface of green tires with a lubricant preparation can, however, be very labor-intensive and noticeably lead to

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contribute to the cost of the tire. The tire must be transported into and removed from the spray chamber, one some time elapses for the sprayed-on lubricant coating to dry. There is therefore a need for an improved one Lubricant system used in molding and Vulcanization of green tires is used.

The invention provides a lubricant which consists of a mixture of the following components consists:

(A) about 10 to about 40, and preferably about 25 to about 35 parts by weight of bentonite clay with a Particle size between about 100 and about 500, and preferably about 200 to about 400 mesh (US standard sieve series),

(B) from about 15 to about 45, and preferably from about 25 to about 35 parts by weight of polydimethylsiloxane a viscosity between about 40,000 and about 120,000, and preferably about 50,000 to about

70000 at 25 ° C,

(C) about 12 to about 36, and preferably about

20 to about 30 parts by weight of polyethylene glycol and / or Polypropylene glycol having a molecular weight between about 1500 and about 2500, and preferably between about 1800 and about 2200,

(D) about 10 to about 25, and preferably about

15 to about 20 parts by weight of one or more surfactants Agents for the polydimethylsiloxane and the poly (alkylene glycol) and

(E) optionally from about 4 to about 12 parts by weight of a stabilizing agent.

The preparation that is applied to the surface of the blister is an aqueous emulsion or dispersion of the ingredients. For example, the preparation contains such Plot also (F) about 500 to about 1500 and preferably about 600 to about 800 parts by weight

Water that after layering on the bladder by evaporation is dried. You can easily use more water, an additional dilution of the preparation however, it reduces the application efficiency. 5

The polydimethylsiloxane can have hydroxyl end groups as a constituent (precursor) in the production of the preparation.

According to the present invention, there is an expandable rubber tire vulcanization bladder provided with an applied coating (especially after water removal). The rubber for the bladder typically consists of a butyl rubber or butyl type rubber (copolymer from isoprene and isobutylene). The term "butyl type" means various modified basic butyl rubbers, for example halogen-substituted butyl rubbers, for example those made from chlorobutyl or bromobutyl rubber can exist.

According to a further embodiment of the invention, a method for producing a pneumatic or semi-pneumatic Tire made available, when it is carried out, a green tire is introduced into a tire mold and the coated expandable bladder of the invention is positioned in the mold. The mold is then closed and the bladder is pressurized by means of an inner hot fluid expands, thereby pressing the tire outwardly against the mold surface and deforming and vulcanizing it will. The mold is then opened, the bladder collapsed and the molded and vulcanized tire removed. The bladder is generally associated with an interior portion of the tire mold itself.

Such a method for molding a pneumatic or semi-pneumatic tire comprises the following stages:

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(A) Building a green tire with elements that form the outer tread for ground contact, two in one Spaced inextensible beads, side walls that extend radially outwardly from the beads and connect to the tread, a supporting carcass with reinforcing elements and a will form the inner surface of a rubber material,

(B) Inserting the green tire into a tire molding press and positioning a coated tire vulcanization bladder according to the present invention into the interior the green tire with the bladder connected to an inner portion of the tire press,

(C) closing the tire mold and expanding the coated tire curing bladder by an internal heated one Fluid outwards against the inner rubber surface of the tire, causing the tire to move outwards under the The effect of heat and pressure is pressed to form and vulcanize,

(D) opening the tire mold, collapsing the bladder and removing the vulcanized tire with an im general toroidal shape.

The term "pneumatic tires" means tires which are kept in operating condition by means of an internal fluid, such as air, under pressure in their tire cavity when they are mounted on a rim, while under the term "semi-pneumatic tires" to understand tires that contain an internal fluid, such as air, in their cavity, but not completely at that pressure at a Assembly are dependent on a rim in its operating condition.

For practicing the invention, the aqueous emulsion or dispersion of the lubricant may be more convenient Way can be produced by a process which comprises the following steps:

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(A) Mixing from about 10 to about 40, and preferably from about 25 to about 35 parts by weight of a bentonite clay having a particle size between about 100 and about 500, and preferably about 200 to about 400 mesh (U.S. Standard Sieve Series) with about 500 to about 1500 and preferably about 600 to about 800 parts by weight of water is pre-heated at a temperature between about 20 and about 95 ⁰ C under high shear mixing conditions, wherein the water preferably to approximately 50 to about 85 ° C, and being mixed as long as until the mixture seems to have thickened,

(B) admixing about 15 to about 45 and preferably about 25 to about 35 parts by weight of a polydimethylsiloxane having a viscosity between about 40,000 and about 120,000 and preferably about 50,000 to about 70,000 at 25 ^° C., about 12 to about 36 and preferably about 20 to about 30 parts by weight of polyethylene glycol and / or polypropylene glycol) having a molecular weight between about 1500 and about 2500 and preferably between about 1800 and about 2200 and a surfactant in an amount of preferably about 4 to about 10 wt. Parts, this surfactant serving for the polydimethylsiloxane and poly (alkylene glycol),

(C) if necessary, admixing approximately

2 to about 10 parts by weight of another surfactant for reduced friction between Bladder and tire,

(D) optionally admixing from about 2 to about 8 parts by weight of a corrosion inhibitor,

(E) optionally admixing from about 0.2 to about 1.0 parts by weight of a defoamer and

(F) optionally admixing from about 2 to about 10 parts by weight of a stabilizing agent.

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Various known defoaming and stabilizing agents can be used to practice the invention.

The aqueous emulsion or dispersion is simply coated on the bladder / for example, by spray coating, and by evaporation at air, for example at a temperature between about 20 and about 110 ⁰ C dried. The bladder is preferably in an approximately 80 to approximately 150% expanded state with respect to the tire vulcanization for this coating (ie it is not in a relaxed state) / it is not necessary to proceed in this way, but can also Bubbles are successfully coated in a somewhat relaxed state.

It was found that if the described coating on a rubber bladder, about 6 to about 9 tires using such a bladder (6 to 9 tire curing cycles) can be molded until excessive adhesion between the contacting The outer surface of the bladder and the inner surface of the tire are identified as being glued together strongly when the bladder collapses after the tire has vulcanized.

Therefore, according to the invention, there is a higher number of vulcanization cycles compared to previously known coating compounds possible.

An essential feature of the lubricant is, of course, the presence of the polydimethylsiloxane fluid. Such a one Coating is a bit greasy unless the bentonite clay is used, which not only gives the greasy appearance of the coated bubble surface eliminated, but also obvious to a noticeable extent causes any trapped air to escape from the surface. The additional

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loaned soap or surfactant can be beneficial in that they increase the sliding between the bladder and tire.

The defoaming agent optionally used can consist of a dimethylpolysiloxane emulsion in water and is beneficial in that there is foam formation during from mixing.

The following examples illustrate the invention without it to restrict. Unless otherwise stated, all parts and percentages relate to weight.

15 Example 1

A lubricant preparation is according to the approach in Table I below prepared.

20 Table I.

material

Bentonite clay (325 mesh) water

Polydimethylsiloxane and .polyglycol

2 25 Surfactant

Rust inhibitor (sodium benzoate)

Defoamer

Stabilizers

According to the information, it is a viscous polydimethylsiloxane fluid with a viscosity of about 60,000 w in a mixture of about 31.3 parts of the polydimethylsiloxane with about 25 parts of polypropylene glycol having a molecular weight of about 2000 and about 6 parts of a surfactant therefor.

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A vegetable sodium oil soap, added if necessary can be.

The aqueous emulsion dispersion is prepared according to the following method:

(A) The water is ^{heated to a temperature of approximately 60 °} C., after which the clay is added. Mix in a Cowles mixer at 2500 rpm for approximately 2 to 5 minutes, the appearance of the mixture indicating that it has thickened.

(B) It becomes the organopolysiloxane fluid mixture under high Shear at 2500 rpm added to obtain a water emulsion.

(C) Additional surfactant is added. (D) The rust inhibitor is added to protect the applicator.

(E) Defoamer silicone is added.

(F) Stabilizing agent is added.

The mixture is sprayed onto the outer surface of the rubber tire vulcanization bladder in an expanded state. It makes the coating dry at about 65 ⁰ C. The coating is reapplied after approximately 4 tire cure cycles, with a maximum of approximately 6 hours between coats.

The coating is left on the hot (65 ° C) bubble surface for approximately 1 minute dried to form a lubricant coating.

The bladder itself is made of a butyl rubber material and is generally toroidal in shape with a Expanded diameter of approximately 975 mm and a tubular diameter of approximately 250 mm. The surface is made by washing with a hydrocarbon solvent and then drying to remove oils or the like. Pretreated.

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A green radial tire with a dimension of 11 R 22.5 is produced"

The tire is placed in a tire molding press and the coated bladder attached to the mold is inserted into the tire. The mold is closed and the bladder is expanded with water vapor at a temperature of approximately 190 ^° C., thereby pressing against the inner surface of the tire and pressing the tire outward against the outer surface of the mold, so that the tire is deformed and vulcanized in the desired shape will.

The mold is then opened, the bladder collapsed, and the tire removed. That way you can form about 6 to about 9 tires using the bladder within a period of 8 hours (curing cycles), before it becomes necessary to re-coat the bladder with the lubricant.

In general, recoating is deemed necessary if the bladder is excessively tight against the interior Surface of the pre-vulcanized tire adheres when the expanded bladder collapses or after vulcanization is relaxed.

25th

The inner surface of the tire is typically made of a mixed rubber material, different rubbers or mixtures thereof being possible, such as Natural rubber, cis-1,4-polyisoprene, cis-1,4-polybutadiene, Butadiene / styrene copolymers, butyl rubber, halobutyl rubber, such as chlorobutyl or bromobutyl rubber, and EPDM (ethylene / propylene / diene (in smaller quantities) terpolymer).

In the case of this example, the preparation was an Ra _ty dialreifens described. The invention is more in itself

for the production of radial tires and not diagonal

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tires because the blisters generally more during the manufacture of a cross-ply tire curing cycle must be expanded, whereby the surface coating of the bladder is more tensioned, the invention however, it can also be used in general for the manufacture of cross-ply tires.

The tire made according to the above example is made by directly expanding the coated bladder produced against the inner rubber surface of the tire, with the tire facing outwards under the action of heat and pressing and molding and vulcanizing the tire. The coated bladder therefore enables effectively produces the tire without the use of a grease coating or a lump coating the inner surface of the green tire. This shows that the coated bladder of the present invention is sufficient Lubrication for a number of consecutive types of tire vulcanization under the action of heat and pressure, provides expansion and contraction without the need for a conventional lining agent or lubricant beforehand must be applied to the inside of the tire. This means considerable labor and material savings in the manufacture of a pneumatic tire. One can apply a lubricant before coating on the inner surface of the tire may be used in conjunction with the coated bladder, but the above example shows that this is not necessary.

Claims (10)

Claims 1. Lubricant, characterized in that it consists of the product of a mixture of the following components: (A) about 10 to about 40 parts by weight bentonite clay with a particle size between about 100 and about 500 mesh (US Standard Sieve Series); (B) about 15 to about 45 parts by weight of polydimethylsiloxane having a viscosity of about 40,000 to mraVs about 120000 at 25 ° C; (C) about 12 to about 31 parts by weight of polyethylene glycol and / or polypropylene glycol having a molecular weight between about 1500 and about 2500; (D) about 10 to about 25 parts by weight of one or several surfactants for the polydimethylsiloxanes and the poly (alkylene glycol) and (E) optionally from about 4 to about 12 parts by weight a stabilizer. 2. Lubricant according to claim 1, characterized in that that the polydimethylsiloxane (B) has hydroxyl end groups. 3. Lubricant according to claim 1, characterized in that that it is present as an aqueous emulsion containing about 500 to about 1500 parts by weight of water. 4. Lubricant according to claim 2, characterized in that it is in the form of an aqueous emulsion, which is approximately Contains 500 to about 1500 parts by weight of water. 5. Use of a lubricant according to claim 1 for coating the outer surface of an expandable Tire vulcanization bladder. 6. Embodiment according to claim 5, characterized in that that the bladder has a coating according to claim 2 on its having outer surface. 7. Process for the preparation of a lubricant according to Claim 1 or 2, characterized in that (A) under high shear mixing conditions about 10 to about 40 parts by weight of bentonite clay with a particle size between about 100 and about 500 mesh (US standard sieve series) with approximately 500 to about 1500 parts by weight water at a temperature between about 20 ⁰ C and about 90 ⁰ C is mixed, appears concentrated until the mixture; (B) while maintaining the temperature of the mixture between about 20 and about 95 ° C, about 15 to about 45 parts by weight of polydimethylsiloxane having a viscosity between about 40,000 and about 120,000 at 25 ° C, about 12 to about 36 parts by weight of poly ethyl eng Iy kol and / or Polypropylene glycol with a molecular weight between between about 1500 and about 2500 and a surfactant Agents for the polydimethylsiloxane and the polyalkylene glycol are admixed; (C) optionally about 2 to about 10 parts by weight another surfactant is admixed; (D) optionally from about 2 to about 8 parts by weight a corrosion inhibitor are incorporated; (E) optionally about 0.2 to about 1 part by weight of a defoamer is added and (F) optionally from about 2 to about 10 parts by weight of a stabilizing agent are mixed in. 8. Use of a lubricant according to claim 3 for Coating the outer exposed surface of an expandable toroidal shaped bladder for vulcanizing a pneumatic or semi-pneumatic tire, wherein coating in about 80- to about 150- % expanded tire cure state takes place. 9. Embodiment according to claim 8, characterized in that that the bladder is a butyl type rubber bladder. 5 10. Embodiment according to claim 9, characterized in that that the dimethylsiloxane used has hydroxyl end groups.