DE3146051A1 - LUBRICANTS, METHOD FOR THE PRODUCTION AND USE THEREOF - Google Patents

Description

MÜLLER-BORE DEUI ¹ tbsp SCHÖN HERTEL

PATBHTAIfWÄITB
EUHOPBAK PATENT ATTORNEYS

DR. WOLFGANG MÜLLER-BORfe (PATENT ACQUISITION FROM 1927-197S) DR. PAUL DEUFEL. DIPL.-CHEM. DR. ALFRED SCHÖN. DIPL.-CHEM. WERNER HERTEL. DIPL.-PHYS.

G 3170

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

Lubricant, method of its
Manufacture and its use

MUNICH 86. SIEBERTSTR. 4 · POB 850 720 · CABLE: MUEBOPAT ■ TEL. (0 89) 4740 OS · TELECOPIER XEROX 400 · TELEX 5-2 »285

3Η6051

description

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

Conventionally, pneumatic rubber vehicle tires are used by molding and vulcanizing a green or unvulcanized or unmolded tire in one Molding press, in which the green tire is pushed outwards against a molding surface by means of a bubble that passes through a internal fluid is expanded, produced. In this way the green tire is molded from the outer mold surface, which shapes the tread pattern of the tire and the configuration of the sidewalls. By letting it work the tire is vulcanized by heat. In general, the bladder is expanded by an internal pressure exerted by a fluid is made available, for example by a hot gas, hot water and / or water vapor, these Fluids also take part in the heat transfer for hardening or vulcanizing. The tire is then left in the mold cool down a little, sometimes adding cold or cooler water to the bladder. Then the form is opened and the bladder collapse by releasing internal pressure left, whereupon the tire is removed from the tire mold. The use of 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. Further there is considerable relative movement between the outer contacting surface of the bladder and the vulcanized inner surface of the tire after molding and vulcanization of the tire during collapse and peeling the bladder off the tire.

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Unless there is adequate lubrication between the bladder and the inner surface of the tire, the bladder tends to buckle or wrinkle, causing undesirable deformation of the tire in the Shape as well as excessive wear and roughening of the bubble surface itself caused. Furthermore, the bubble surface tends to sticking to the inner surface of the tire after the tire is vulcanized and during the Collapse of the bladder during the tire curing cycle. Furthermore, air bubbles can be trapped between the bubble and the tire surfaces and tire vulcanization defects as a result of sufficient heat transfer condition.

For this reason, it is conventional practice to use the inner surface of the green or unvulcanized tire a lubricant "to be coated in order to provide lubrication between ■ see the outer bladder surface and the inner tire surface to ensure during the tire molding.

Some people use the lubricant as a lining agent (lining cement). Conventionally, the inner surface of the green tire, which in typical Way made of a rubber material, simply sprayed with a lubricant in a ventilated spray chamber, which can for example be based on a silicone polymer. Other additives can also be used in a conventional manner can be used in a lubricant preparation, 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. Often aqueous soap solutions are used. Lots of lubricants are known for these purposes.

Conventional spray-coating of the inner surface of the green tire with a lubricant requires one intensive workload, which has a significant impact on the cost of the tire.

The tire must be transported into and out of the spray chamber be transported away again, and it must also be left to dry the sprayed-on spray.

There is therefore a need for an improved lubrication system for molding and curing green tires.

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 15 and about 25

mmVs
Millions at 25 ° C;

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

mmVs
70,000 at 25 ^° C;

(D) about 12 to about 36, and preferably about 20 to about 30 parts by weight of poly (ethylene glycol and / or propylene glycol) with a molecular weight between approximately 1,500 and approximately 2,200> (E) about 10 to about 25, and preferably about 15 to about 20 parts by weight of surfactants for the polydimethylsiloxanes and the poly (alkylene glycol); as

. (F) optionally from about 4 to about 12 parts by weight of a stabilizing agent, based on the total. amount of polydimethylsiloxanes.

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The preparation for application to the bladder surface

; is an aqueous emulsion or dispersion of the constituents.

, For example, the preparation to be applied can also

j (G) about 500 to about 1,500 and preferably approximately

'5 contain about 600 to about 800 parts by weight of water, the

removed by evaporation after application to the bladder ; is drying. You can also use more water, with

however, further dilution of the preparation will reduce the efficiency of its application.
10

It is generally preferable to use a polydimethylsiloxane (B) or (C) with hydroxyl end groups (hydroxyl capped) as a constituent for the preparation (precursor) of the preparation.
15th

The polyalkylene glycol (D) is produced from at least one of the substances poly (ethylene glycol), poly (propylene glycol) or mixtures thereof. Polypropylene glycol is preferred.
20th

The invention provides an expandable rubber tire vulcanization bladder with a coating as described above, especially after removal of water. The rubber for the bladder is typically a butyl or butyl type rubber (Copolymer of isoprene and isobutylene). The term "butyl type" includes various modified base butyl rubbers to understand how halogen-substituted butyl rubbers, for example from chlorobutyl rubber or bromobutyl rubber.

The invention also provides a method of making a pneumatic or semi-pneumatic rubber tire is made available, when carried out 5 a green tire is placed in a tire mold, whereupon the coated expandable bladder according to the present invention is introduced into the mold, which is then closed will. The bladder is then passed through by an inner one

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The pressure generated by the hot fluid expands and forces the tire outward against the mold surface, causing the tire is molded and vulcanized. Then the mold is opened, the bubble collapsed and the molded one and removed from vulcanized tires.

In particular, there is such a method for forming a pneumatic or semi-pneumatic tire from the following stages:

(A) Manufacture or build a green tire with components that shape its outer tread, the Contacting bottom, two spaced inextensible beads, side walls that extend radially extending outwardly from the beads and connecting to the tread, a supporting carcass with reinforcing elements and will form an inner surface of a rubber material;

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

(C) Closing the tire mold and expanding the coated tire vulcanization bladder by an internal heated one Fluid outward against the inner rubber surface of the tire, causing the tire to undergo outward under the action of heat and pressure, the tire being molded and vulcanized j

(D) opening the tire mold, collapsing the bladder and removing the vulcanized tire having a generally toroidal shape.

By the term "pneumatic tires" are to be understood tires that are an internal fluid, such as Air, under pressure, operate in their tire cavity for their functioning when mounted while mounted on a rim the term "semi-pneumatic tires" is to be understood as meaning tires which have an internal fluid, such as air, in their

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Contain cavity, but not entirely on the pressure of this fluid when mounted on a rim have to rely for their functioning.

Various lubricant mixtures or preparations have already been investigated as coatings for tire blisters .

For example, lubricants that contain silicone compounds in organic solvents have been investigated. However, difficulties were found which are apparently due to the fact that the organic solvent in the formulation destroys or worsens the rubber surface of the bladder itself. The organic solvent itself is dangerous in terms of its flammability and toxicity. In addition, it was found that the organic solvent based coatings tested only lasted about 4 to 6 tire cure cycles before it was deemed necessary to recoat the bladder surface. Such a frequency of a re-coating is economically disadvantageous _r in particular taking account of the risks involved.

To carry out the invention in practice, the aqueous Emulsion or dispersion of the lubricant preparation can be conveniently prepared by a method consisting of the following stages:

(A) Under high shear mixing conditions, 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 50 0, and preferably 200 and about 400 mesh (US Standard Sieve Series) with about 500 to about 1,500 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, the water being preferably about 50 to about 85 ° C, mixed until the mixture

seems to have thickened.

(B) Then, approximately under high Scheritiischbedingungen 15 to about 45 and preferably about 25 to about 35 parts by weight of a polydimethylsiloxane having a viscosity between about 15 and about 25 million centistokes at ⁰ C and about 3 to about 25 parts by weight admixed with a surfactant for the polydimethylsiloxane,

(C) then 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 to 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 propylene glycol having a molecular weight between about 1,500 and about 2,500 and preferably about 1,800 and about 2,200 and about 4 to about 10 parts by weight of a surfactant Agent for the polydimethylsiloxane and poly (alkylene

glycol).

(D) Optionally, about 2 'to about 10 parts by weight another surfactant for reduced friction between bubbles and tires added;

(E) optionally, about 2 to about 8 parts by weight admixed with a corrosion inhibitor L;

(F) optionally becomes about 0.2 to about 1.0 Parts by weight of a defoaming agent added; and

(G) optionally, about 2 to about 10 parts by weight a stabilizing agent mixed in.

Various known defoaming agents as well as various Stabilizing agents can be used in practicing the invention.

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The aqueous emulsion or dispersion is easily applied to the bladder, for example by spray coating, and by evaporation at a temperature of for example about 20 to about 110 ⁰ C dried. Preferably, the bladder is about 80 to about 150% of its tire cured expanded state for this coating purpose (ie, it has not collapsed), but this is not considered necessary and bladders have also been successfully coated in a somewhat collapsed state.

Various aqueous emulsions or dispersions based on silicones or siloxane have heretofore been known as Vulcanization bubble coatings formulated and investigated. Such preparations were previously with the viscous Polydimethylsiloxane fluid (C) used. The experience has shown, however, that when a bladder with a coating made therefrom was used, only approximately 6 to 9 tires formed using such a bladder (6 to 9 tire curing cycles) because of excessive adhesion between the outer surface the bladder and the inner surface of the tire was detected, which indicated that the blister was excessively adhered to the tire upon collapse after the tire was vulcanized. After Addition of the viscous organopolysiloxane polymer to the blend was found to be about 10 to about 15 tires with the bladder (10 to 15 cycles) could be molded before excessive adhesion (sticking) between the surfaces was detected.

An essential feature of the lubricant formulation is, of course, the presence of both types of polydimethylsiloxane polymers (B and C), which comprise both a highly viscous polymer and a somewhat viscous fluid. A cover however, some of these materials are greasy unless the bentonite clay is used, which is not just the greasy one

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The appearance of the coated bubble surface is eliminated, but also noticeably trapped air is pushed out of the surface. Any additionally added
Soap or a surfactant may be beneficial. as it obviously increases the slipperiness between the bladder and the tire. ·

The optionally added defoaming agent can consist of a dimethylpolysiloxane emulsion in water and
prevents or suppresses foam formation during mixing.

The following example illustrates the invention without relating it restrict. Unless otherwise stated, all parts and percentages relate to weight. ·

example 1

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

Table I material

Bentonite clay (325 mesh)
water
Polydimethylsiloxane (hydroxyl end groups) |

Polydimethylsiloxane ² $ 62.8.

Surfactant

Rust inhibitor (sodium benzoate)
Defoaming agents
Stabilizers

1. According to the manufacturer's information, it is a poly- ' dimethylsiloxane with a viscosity of about 20 Millions in a mixture of about 31.3 parts of the polydimethylsiloxane and about 11.6 Sharing a surfactant therefor.

2. According to the manufacturer, it is a viscous polydimethylsiloxane fluid with a viscosity of approximately 60,000 - in a mixture of approximately J 10 31.3 parts of the polydimethylsiloxane and approximately 25 parts

len polypropylene glycol with a molecular weight of

\ About 2,000 and about 6.3 parts of a surfactant for it.
J

3. A vegetable sodium oil soap.

The aqueous emulsion dispersion is made by the following method manufactured:

(A) The water is ^{heated to a temperature of approximately 60 °} C. and the clay is added. Mix in a Cowles mixer at 2500 rpm for approximately 2 to 5 minutes until the mixture has reached an apparently thickened state.

25th

(B) The organopolysiloxane polymer becomes mixed under shear (2,500 rpm) added to obtain a water emulsion.

r 30 (C) Under high shear mixing conditions, the viscous

fluid mixture of organopolysiloxane and polyglycol added.

(D) Additional surfactant is added.

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(E) The rust inhibitor is added to protect the apparatus, APPLICATION: ^5.

(F) The silicone defoaming agent is added,

(G) The stabilizing agent is used in an amount of 10%, based on the total amount of the siloxane poly-

■ 5 kidneys and the siloxane concentrate (B and C), added.

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

The coating is dried on the hot (65 ° C) bubble surface for approximately 1 minute, creating a lubricant coating is formed.

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

A radial tire with a dimension of 11 R 22.5 will be manufactured.

The tire is placed in a tire molding press and the coated bladder associated with the mold is placed inside the tire. The mold is then closed and the bladder is expanded by means of water vapor at a temperature of approximately 190 ^° C., whereby it is pressed against the inner surface of the tire and the outer surface of the tire is pressed onto the mold, whereby the tire is formed in the desired shape and is vulcanized.

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The mold is then opened, the bladder relaxed, and the tire removed. Using this method, about 10 up to about 15 tires using the bladder for a period of about 8 to 13 hours (curing cycles) before it becomes necessary to recoat the bladder with the lubricant.

In general, a recoating is deemed necessary if the bladder is excessively strong on the interior Surface of the vulcanized tire adhered when collapsing after vulcanization.

The inner surface of the tire is typically made of a mixed rubber material which can consist of different rubbers or mixtures thereof, for example Natural rubber, cis-1,4-polyisoprene, cis-1,4-polybutadiene, Butadiene / styrene copolymers, butyl rubber, halobutyl rubber, such as chlorobutyl and bromobutyl rubber, and EPDT (ethylene / propylene / diene terpolymer> where the diene is present in a smaller amount).

■ j, The present example was taken in connection with the

; position of a radial tire explained. The invention is

although better suited for the production of radial tires than for the manufacture of cross-ply tires, as the bubbles are generally expanded more during the vulcanization cycle in the manufacture of cross-ply tires , must, so that the surface coatings of the bubbles

> be exposed to stronger tensions, nevertheless the

However, the invention also applies to the manufacture of cross-ply tires applicable and not limited to the manufacture of radial tires.

The tire produced according to the example described was produced by the coated bladder directly was pressed against the inner rubber surface of the tire,

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whereby the tire outwards under the action of heat and pressure to form and vulcanize the tire was pressed. The coated bladder therefore enables the tire to be manufactured without the use of a lubricating coating or lining agent on the inner surface of the green tire. This is an essential fact since it is clearly demonstrated in this way that the inventive coated bladder provides adequate lubrication during a number of tire cure cycles exposure to heat and pressure, and expansion and contraction without a conventional tire liner (liner cement) or lubricant, which is previously applied to the surface of the tire. this requires considerable labor and material savings in the manufacture of a pneumatic tire. Yet one can combine a lubricant precoat on the inner surface of the green tire if desired with the coated bladder, but the present example has shown that this is not necessary is.

Claims (10)

- 1 claims 1. Lubricant, characterized by (A) about 10 to about 40 parts by weight bentonite clay having a particle size between about 100 and about 500 mesh (US Standard Sieve Series); (B) about 15 to about 45 parts by weight of polydimethyl siloxane with a viscosity between about 15 and mm Vs about 25 million at 25 ° C; (C) about 15 to about 45 parts by weight of a poly dimethylsiloxane with a viscosity between mm ² / s from about 40,000 to about 120,000 - at 25 ° C; (D) about 12 to about 31 parts by weight poly (ethylene glycol) and / or propylene glycol having a molecular weight between about 1,500 and about 2,500; (E) about 10 to about 25 parts by weight more surfactant Agents for the polydimethylsiloxanes and the poly (alkylene glycol); and (P) optionally from about 4 to about 12 parts by weight of a stabilizing agent. 2. Lubricant according to claim 1, characterized in that that at least one of the polydimethylsiloxanes (B) and (C) has hydroxyl end groups.
25th 3. Preparation according to claim 1, characterized in that the (alkylene) glycol consists of poly (propylene glycol). 4. Preparation according to claim 3, characterized in that that the polydimethylsiloxane (B) has hydroxyl end groups. 5. Composition according to claim 1, characterized in that it is in the form of an aqueous emulsion, the approximately Contains 500 to about 1,500 parts by weight of water. * Λ 6 B. 6. Composition according to claim 2, characterized in that it is present as an aqueous emulsion, which is about 500 to about Contains 1,500 parts by weight of water. 7. Means according to claim 4, characterized in that it is in the form of an aqueous emulsion containing from about to about 1,500 parts by weight of water. 8. Composition according to claim 5, characterized in that it is in the form of an aqueous emulsion, the approximately contains up to about 1,500 parts by weight of water. 9. A method for producing an agent according to claims 1 to 8, characterized in that (A) under high shear mixing conditions about 10 to about 40 parts by weight bentonite clay having a particle size between about 100 and about 500 mesh (US Standard Sieve Series), with about 500 to about 1,500 parts by weight of water which has been preheated to a temperature of about 20 to about 95 ⁰ C, be mixed until the mixture thickens appears; (B) under high shear mixing conditions about 15 to about 45 parts by weight of a polydimethylsiloxane with a viscosity between about 15 and approx Fähr 25 million at 25 ⁰ C and about 3 to about 25 parts by weight be admixed with a surface active agent for the polydimethylsiloxane; (C) about 15 to about 45 parts by weight of polydimethyl siloxane having a viscosity between about 40,000 itiinys
and about 120,000 at 25 ° C, about 12 to about 36 parts by weight of polyethylene glycol and / or propylene glycol) having a molecular weight between about 1,500 and about 2,500 and less about 4 to about 10 parts by weight of a surfactant for the polydimethylsiloxane and the Alkylene oxide polyol are added; 3U6051 possibly (D) about 2 to about 10 parts by weight of another surfactants are admixed; (E) optionally from about 2 to about 8 parts by weight ■ 5 "of a corrosion inhibitor are mixed in; (F) optionally about 0.2 to about 1.0 parts by weight a defoamer are added and (G) optionally from about 2 to about 10 parts by weight of a stabilizing agent are incorporated. 10. Use of a preparation according to claims 1 to 9 for coating a tire vulcanization bladder.