SK154099A3 - Mould release agent, its use and method for vulcanizing tires - Google Patents

Abstract

A mold release agent comprising an aqueous emulsion containing a condensation- or addition-crosslinking silicone system (A or B respectively) with at least 2 components and (C) aqueous colloidal silicic acid (silica sol). An Independent claim is also included for a process for vulcanizing pneumatic tires in which a mold release agent as described above is applied to the bladder and/or the tire blank before vulcanization.

Description

BACKGROUND OF THE INVENTION The present invention relates to a filler-free molding release agent consisting of an aqueous emulsion of cross-linking silicone systems and a silica sol, which at the same time imparts good slip properties to the treated surface. The mold release agent is particularly suitable as a mold release agent in the manufacture of tires and other rubber goods and is used to mold and vulcanize such products.

BACKGROUND OF THE INVENTION

According to the prior art, tires are formed and vulcanized by inserting the tire blank into a mold and pressing it against the mold by means of a heating membrane (bladeer, moss), vulcanizing under the action of heat. The heating membrane must slide in the workpiece blank and be removed from the tire after curing. Therefore, the tire blanks are conveyed to the spray booth where they are rotated by a mechanical jig. A spray gun is inserted into the rotating blank to spray the release agent solution into the blank. The overspray is usually disposed of by a water curtain and remains in the water. Subsequently, the blank is formed and vulcanized in the vulcanizing press by means of a heating membrane, which is intended to heat the tire blank and press the tire into a negative mold under high pressure.

Aqueous emulsions of organopolysiloxanes and their use as a release agent in tire molding and vulcanization are known in the art. US-A 4,184,880 discloses an emulsion of release agents which, however, contain a greater amount of inorganic silicates than fillers which are

31330 / H hydrophobizing their surfaces treated with organosilicon compounds.

US-A 4,431,452 discloses an aqueous formulation with a release agent comprising:

1) SiOH-terminated polydimethylsiloxane with a viscosity of up to 25,000,000 centistokes at 25 ° C;

2) SiOH-terminated polydimethylsiloxane with a viscosity of up to 120,000 centistokes at 25 ° C;

3) polyalkylene glycol;

4) bentonitone; and

5) a surfactant.

US-A 4,359,340 discloses aqueous formulations with a release agent for use in forming tires. Emulsions consist of:

1) a polydimethylsiloxane having a viscosity of up to 25,000,000 centistokes at a temperature of ° C;

2) methyl hydrogen silane having a viscosity of 20 to 40 centistokes or dimethyl hydrogen silane having a viscosity of 80 to 120 centistokes;

3) metal salts of organic acid; and

4) a surfactant.

EP-A 0 279 372 discloses aqueous emulsions of organopolysiloxanes which can be used as a release agent in the formation and vulcanization of tires, and in particular for coating on a membrane, comprising:

1) SiOH-terminated polydimethylsiloxane polymer with a plasticity of 50 to 50

100;

2) an organohydrogen polysiloxane having an average of at least two Si-bonded hydrogen atoms per molecule;

3) lubricants having a melting point of 25-80 ° C;

4) inorganic silicate (Mica);

5) thickeners;

6) a surfactant; and

7) water.

A disadvantage of the compositions described above with a release agent

3I330 / H is a relatively large amount of inorganic silicates as fillers, which have a negative effect on the stability of the emulsions, and crosslinking, which occurs by reaction of the SiOH-SiH groups with hydrogen cleavage, which is undesirable due to the risk of explosion.

EP-A 0 635 559 discloses a composition with a tire mold release agent which does not exhibit undesirable hydrogen evolution. The described emulsions are used to form a coating on a membrane and consist of:

(1) at least one non-reactive polydimethylsiloxane having a kinematic viscosity between 50 and 30,000,000 mm s ^-1 at 25 ° C;

2) at least one reactive polydimethylsiloxane having a kinematic viscosity of between 15 and 5,000,000 mm s ^-1 ;

(3) crosslinking agent:

4) a surfactant; and

5) water.

EP-A 0 111 100 discloses a silicone-based tire release agent which is not only soluble in an organic solvent and thus ready for use, but additionally has to contain kaolin, chalk, stone meal, silicas, carbon black or graphite. The heating membrane then does not have to be rough enough to ensure sufficient air removal.

By lubricants alone, for example Si-oils or Si-oil emulsions, a sufficient sliding and separating effect can be achieved, but unfortunately not the complete "venting" of the airflow between the heating membrane and the tire blank.

Enclosed air means tires that are confused because under the air bubble there is insufficient vulcanization.

Fillers (mineral or other) are needed to maintain the separation between the membrane and the blank so that air can escape before vulcanizing.

In particular, due to the venting, it was not possible to use filler-free internal solutions consisting solely of mixtures of release agents or glidants. The fillers fulfill the function of a means for maintaining the distance between the inner profile of the workpiece and the membrane.

31330 / H

Until now, the use of conventional silicone oils causes undesirable separation on the tire sidewalls.

Therefore, as before, there remains a need for an aqueous solvent-free release agent that can be sprayed onto the inside of the tire blank and / or the membrane surface while meeting all of the vulcanization requirements, namely sliding, separation and venting, without the disadvantages described above. such as filler content and / or crosslinking by hydrogen cleavage. Furthermore, it should prevent separation on the side of the tire.

SUMMARY OF THE INVENTION

The invention relates to a mold release agent comprising in an aqueous emulsion a system comprising at least two silicone components reacting with each other with crosslinking, the system being selected from the group consisting of (A) silicone components reacting with each other by condensation or (B) silicone components reacting with each other and aqueous colloidal silicic acid (silica sol)

Accordingly, the invention also relates to a method of vulcanizing tires, characterized in that a composition with a release agent according to the invention is applied to the membrane and / or the surface of the tire before vulcanizing.

The process according to the invention is particularly environmentally friendly, since about 10% of the active solid of the separating substance suffices in comparison with the conventional processes of the prior art and is accordingly reasonably economical.

The crosslinking silicone systems (A) or (B) according to the invention are mixtures of emulsions of the silicone components (A) interacting (crosslinking) under condensation or mixtures

31330 / H emulsions of silicone components (B) reacting (crosslinking) by addition, which will be described in more detail below. Both reaction systems are catalyzed by suitable catalysts.

A. Condensation of cross-linking silicone systems

These systems are mixtures of aqueous emulsions of polydimethylsiloxanes terminated with Si-OH (A-1) and alkoxy-functional silicones (A2).

The Si-OH (A-1)-terminated polydimethylsiloxane emulsion contains siloxane in an amount of 20 to 80% by weight, preferably 30 to 60% by weight, based on emulsion A-1.

The crosslinking alkoxy-functional silicone (A-2) emulsion contains siloxane in an amount of 20 to 80% by weight, preferably 25 to 60% by weight, based on emulsion A-2.

The two emulsions are mixed in a quantity ratio of A-1: A-2 of 20: 80 to 80: 20, preferably 40: 60 to 60: 40. Both emulsions of course contain suitable emulsifiers conditional on their production.

Emulsion A, made from emulsion A-1 and emulsion A-2, contains 20 to 80% by weight, preferably 30 to 60% by weight silicone, based on emulsion A.

A-1: Emulsion of Si-OH terminated polydimethylsiloxane

The polydimethylsiloxanes terminated by Si-OH are polymers of formula I:

HO [Si (CH ₃ ) 2 -O] _p H (I) wherein p = 400 to 300, preferably 800 to 200.

The preparation of long-chain silicone oil emulsions terminated by -OH emulsion polymerization is known to those skilled in the art, for example, from US-A 2 891 920 or GB-A 1 024 024. A process disclosed in GB-A 1 024 024 using alkylbenzenesulfonic acid as catalyst is particularly preferred. so that both an emulsifier and a polymerization catalyst are available in one. After the polymerization has been carried out, the acid is neutralized so that the catalytic properties are subsequently blocked while the emulsifying properties are fully maintained or even improved. Accordingly, the concentration of the emulsifying agent may be

31330 / H are kept low and there are no interfering foreign molecules from the catalyst after the emulsion has been evaluated. However, n-alkylsulfonic acids may also be used in place of said alkylbenzenesulfonic acids. In addition, emulsifiers other than co-emulsifiers may also be used in addition to the cationic sulfonic acids.

Such co-emulsifiers may be of the non-ionic or ionic type. Suitable anionic co-emulsifiers are, in particular, the salts of the abovementioned nalkyl-alkylbenzenesulfonic acids. Nonionic co-emulsifiers are polyoxyethylene derivatives of fatty alcohols, fatty acids and the like. Examples of such emulsifying agents are POE (3) -lauryl alcohol, POE (20) -oleyl alcohol, POE (7) - nonylphenol or POE (10) stearate (a method of registering POE (3) -lauryl alcohol means that one molecule of lauryl alcohol adds 3 units of ethylene oxide, where 3 represents the mean value). Such nonionic emulsifiers are generally known to those skilled in the art. The added co-emulsifiers increase, on the one hand, the stability of the emulsion formed after the emulsion polymerization, but at the same time they have an effect on the chain length of the long-chain silicone oil and the OH-termination formed during the polymerization.

In general, those silicone oils which are formed by emulsion polymerization in the presence of nonionic co-emulsifiers have a lower molecular weight than those in which no co-emulsifier has been used. The molecular weight control of the OH-terminated silicone oils resulting from emulsion polymerization is further effected by the temperature at equilibrium between siloxane, water and silanol, which is first formed by opening the siloxane ring.

Particularly preferred for the production of long chain silicone oil emulsions and OH-terminations is the method described below.

Octamethylcyclotetrasiloxane (D 4) is used as the monomer in an amount to form a 40% emulsion. The sulfonic acid catalytic for emulsion polymerization is n-alkylsulfonic acid. This sulfonic acid was used at 4%, based on the amount of D-4. Co-emulsifiers are the sodium salt of the sulfonic acid used as catalyst and POE (S) -lauryl alcohol. The temperature of the emulsion polymerization is 60 ° C, neutralized

31330 / H with triethanolamine.

One particularly preferred terminated polydimethylsiloxane emulsion is a 40% aqueous polydimethylsiloxane emulsion of formula I wherein p has a value between 800 and 2000.

A-2: Emulsion of alkoxy-functional silicone oils

The alkoxy-functional silicone oil contained in the emulsion A-2 of the invention and capable of crosslinking consists of units of general structure;

R n R m Si Si (4-n-m) 2 (II) wherein is

R is the same or different, optionally substituted hydrocarbon radicals having from 1 to 18 carbon atoms,

R is the same or different, Si-C bonded and polar groups containing substituted hydrocarbon radicals, n an integer of 0, 1, 2 or 3, m an integer of 0,1,2 or 3, and the sum of n + m assumes average values of 1.8 to 2.2 am are chosen such that the polyorganosiloxane contains at least one residue R.

Preferably, the sum of n + m has an average value of 1.9 to 2.1.

Examples of the hydrocarbon radicals R are the alkyl radicals methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, tert-burtyl, n-pentyl, neo-pentyl, tert-pentyl; hexyl radicals such as n-hexyl; heptyl residues such as n-heptyl; octyl residues such as n-octyl and iso-octyl residues such as 2,2,4-trimethylpentyl; nonyl radicals such as the n-nonyl radical; decyl residues such as the n-decyl residue; dodecyl residues such as the n-dodecyl residue; octadecyl residues such as the n-octadecyl residue; alkenyl radicals such as vinyl, alkyl and 5-hexen-1-yl radicals; cycloalkyl radicals such as cyclopentyl, cyclohexyl, cycloheptyl radicals and methylcyclohexyl radicals; aryl radicals such as phenyl, naphthyl, and anthryl and phenanthryl radicals; alkylaryl radicals such as o-, m- and p-tolyl radicals, xylyl radicals and ethylphenyl radicals; aralkyl radicals such as benzyl radical, α- and β-phenylethyl radical.

Examples of optionally substituted hydrocarbon radicals R are oxygen-bonded substituted and unsubstituted hydrocarbon radicals R

31330 / H atom bonded directly to the silicon atom according to the above examples, in particular alkoxy radicals having 1 to 18 carbon atoms and phenoxy radicals, in particular methoxy, ethoxy, η-propoxy, iso-propoxy and phenoxy radicals. Preferably, at most 10% of the R residues are optionally substituted hydrocarbon residues.

Preferably, the radicals R are a methyl, ethyl, phenylmethoxy and / or vinyl radical. For ease of availability, preferably 50% of the R residues, in particular at least 80% of the R residues are methyl residues.

R may be selected from the group of radicals R. Preferably, R is selected from the group of amino-functional hydrocarbon radicals, for example aminoalkyl radicals, such as the gamma-aminopropyl radical and the beta-aminoethyl-gamma aminopropyl radical; aminoalryl residues; SiC bonded, cyclic, amino-functional residues.

Examples of preferred amino-functional radicals R are those of the general formula

-R ¹ - [NR ² (CH ₂ ) _a ] bNHR ² (III) wherein is

R ^{1 is a} divalent hydrocarbon radical having 1 to 18 carbon atoms,

R ² hydrogen or an optionally substituted hydrocarbon radical having 1 to 18 carbon atoms, a is 2, 3, 4, 5 or 6 and b has a value of 0.1, 2, 3 or 4.

Examples of divalent hydrocarbon radicals having 1 to 18 carbon atoms R ¹ are saturated alkylene radicals having straight, branched, or cyclic, such as the methylene and ethylene radicals, also propylene, butylene, pentylene, hexylene, 2-methylpropylene, cyclohexylene and octadecylene radicals, or unsaturated alkylene or arylene radicals such as the hexenyl radical and the phenylene radicals, the npropylene radical and the 2-methylpropylene radical being particularly preferred.

Examples of the optionally substituted hydrocarbon radicals R ² having 1 to 18 carbon atoms as described herein for R

In the above general formula (III), they are preferably

31330 / H

R ^{1 is a} divalent hydrocarbon radical having 2 to 6 carbon atoms,

R ² hydrogen, methyl or cyclohexyl radical, and the value 2 or 3 and b is 0, or the first

Particularly preferred cross-linking alkoxy-functional silicones, which also contain amine groups, are partially branched polydimethylsiloxanes of the structure:

O (SiMe ₂ ) _x OR

I

R-Si-O (SiMe ₂ ) _x OR (IV)

I

O (SiMe ₂ ) _x OR where is

RH ₂ N (CH ₂ ) 2 NH (CH 2) 3 - or H ₂ N (CH ₂ ) ₃ CH ₃

I

RC ₂ H ₅ or - C - CH ₂ NH ₂

I

H

Me CH ₃ , x = 20 to 200.

For the preparation of such compounds and suitable emulsifiers, reference is made to EP-A 0 646 618.

The emulsions comprising an alkoxyfunctional silicone capable of crosslinking may further comprise 2 to 20% by weight, preferably 5 to 15% by weight of an alkoxyfunctional silicone resin of the formula V

R ³ dSi (OR ⁴ ) _e O ₍ 4 _{d e)} , ₂ (V) where is

R ³ monovalent hydrocarbon radical having 1 to 14 carbon atoms, preferably a methyl radical,

R ^{4 is a} monovalent hydrocarbon radical having 1 to 18 carbon atoms,

31330 / H preferably a methyl radical, and a d value of 0.75 to 1.5, preferably about 1, and an e value of 0.2 to 2, preferably 0.4 to 1.2.

The viscosity of this resin is 2 to 2000, preferably 20 to 200 mPa.s.

The preparation of these alkoxy-functional resins is known and is carried out by reacting the corresponding alkyl and / or aryl chlorosilanes with alcohol and water (cf. e.g. GB-A 685 173, DE-A 958 702, FR-A 1 475 709, US-A 3 668 180, DE-A 2 061 189, DE-A 2 444 529, DE-A 2 532 887, EP-A 0 003 610, DE-A 3 000 782).

A particularly preferred methyl-methoxy-silicone resin is prepared by reacting methyltrichlorosilanes with methanol and water. Alternatively, mixtures of methyltrichlorosilane and other alkyl- and / or arylchlorosilanes and / or tetrachlorosilanes may also be used to produce alkoxy-functional silicone resins without compromising the stability of the emulsion of the invention. Mixtures of different alcohols and / or different alkoxy-functional silicone resins may also be used to make the resin without adversely affecting the stability of the emulsion.

The preparation of emulsions from the described alkoxy-functional silicone resins is known from DE-A 3 323 909.

Suitable catalyst active compounds (catalyst emulsions) for crosslinking reactions between Si-OH-terminated polydimethylsiloxanes and aminofunctional silicones in the emulsion are those described in the known literature for condensation and esterification reactions. The catalysts are used at the usual concentrations described in this literature.

B. Addition of crosslinking silicone systems

These systems are an emulsion B comprising an emulsion mixture comprising an organopolysiloxane B-1 having at least two unsaturated hydrocarbon groups and an emulsion containing methyl hydrogen polysiloxane B-2 in addition to the catalyst.

Emulsion B, made from emulsions B-1 and B-2, contains 20 to 80%

31330 / H by weight, preferably 30 to 60% by weight, based on emulsion B.

The organopolysiloxane B-1 having at least two unsaturated hydrocarbon groups within the meaning of the invention is preferably a cyclic, linear or branched polysiloxane containing units of the formula (R ⁵ ) f (R ⁶ ) h SiO _(4- fh) / ₂ (VI) where

R ⁵ alkenyl of 2 to 8 carbon atoms and / or an unsaturated ether radical of 3 to 10 carbon atoms such as vinyl, allly, 1-butenyl, 1-hexenyl and / or - CH ₂ -CH ₂ CH ₂ OCH ₂ CH = CH 2 and so on,

R ^{6 is a} monovalent saturated or substituted hydrocarbon radical having up to 10 carbon atoms from the group of substituted or unsubstituted alkyl-, aryl- and arylalkyl radicals, f and f being integers within the following limits: 0 <f <3 or 0 <h <3a0 <f + h <4 and each individual R ⁵ or R ⁶ within the molecule may be the same or different.

Preferably, ^R5 = vinyl or allyl, most preferably vinyl.

Examples of R ⁶ are methyl, ethyl, propyl, isopropyl, butyl, octyl, and so on, cyclobutyl, cyclopentyl, cyclohexyl and so on, phenyl, tolyl, xylyl, naphthyl and so on benzyl, phenylethyl phenylpropyl. In one preferred embodiment, some or all of the hydrogen atoms of the alkyl, aryl and arylalkyl radicals R ^{6 are} substituted with fluorine and / or chlorine, bromine or iodine atoms and / or cyano radicals. In this case corresponds to ^R6 as chloromethyl radical, trifluoropropyl-, chlorophenyl, dibrómefenyl-, β-cyanoethyl, βkyanopropyl- or gamma-cyanopropyl. Preferably, however, at least 90% of the R ⁶ residues are methyl.

In one preferred embodiment, f is 0 or 1.

Using a nomenclature known to those skilled in the art, where M = (CH ₃ ) ₃ SiO ₁ , 2

D = (CH ₃₎ SiO 2/2 / 2 T = _{(CH3) SiO3} / ₂ M ^vi = (CH 2 CH (CH 3) 2 SiO / 2 D ^vi = (CH2-CH) _(CH3) SiO ₂ of2

31330 / H, the following examples can be given for component B-1:

M ₂ DiooD ^v, 3; M ^vi 2D18o, M ^vi MDiooD ^vi 3l T ₅ D ₅ 5oM ^v, 7, T ₃ D ₅ ooM ^v, 2M ₃ and / or T ₆ D ₃ ooD ^v, M ₄ M ^vi 4.

The molar proportion of unsaturated radicals of type R ⁵ can be selected arbitrarily.

In the component B-1, the molar proportion of unsaturated R-type residues should preferably be 0.01 and 10 mmol / g, particularly preferably between 0.05 and 1 mmol / g and very particularly preferably 0.1 to 0.7 mmol / g of the component B-1. The viscosity of component B-1 is preferably between 10 and 100,000 mPa · s, particularly preferably 50 - 100 000 mPa · s at 25 ° C.

In one preferred embodiment of the invention, the organopolysiloxane described in DE-A 43 28 657 is used as component B-1, since it is branched, the ratio of the number of diorganosiloxyl units (D-units) to the number of branched sites is 15 to 40, at least one triorganosiloxyl unit (M-unit) and at most half of all M-units do not contain unsaturated residues, the remaining M-units are not only one unsaturated residue and the content of unsaturated residues is 0.1 to 1 mmol / g.

The branching points of the component B-1 is preferably monorganosiloxylové units, i.e. trifunctional siloxy units (T-units), but which may also be partially replaced also tetrafunctional siloxyl units (SiO _4/2 .jednotky, Q-units).

The end groups of the branched organopolysiloxane free of unsaturated residues act as an internal plasticizer. The flexibility of the crosslinked film can be controlled by the number of end groups (M-units) not containing unsaturated residues.

Examples of preferred components of B-1 are compounds of the formula:

T5D ₂ ooM ^vl sM2, T7D28oM ^VI 5M4, T ₆ D ₁₈₀ D ^vi 2M ^vi 4M ₄ and / or Τβ0 ₂ 5οΜ ^νΐ 7Μ ₃ .

The branched organopolysiloxanes B-1 containing at least two unsaturated hydrocarbon groups can be produced by conventional methods such as hydrolysis of chlorosilanes and subsequent polymerization with low molecular weight cyclic diorganopolysiloxanes.

The methylhydrogen polysiloxane B-2 preferably contains units of the general formula

31330 / H

Hj (R ⁷⁾ _a SiO _(4-ik) / 2 (VII) wherein R

R ^{7 is a} monovalent, saturated, optionally substituted hydrocarbon radical having up to carbon atoms from the group of substituted and unsubstituted alkyl-, aryl-, arylalkyl- and / or C 2 -C 6 -alkenyl radicals, where both integers where 0 <k <3a0 <j < 2a0 < j + k < 4, preferably 0 < j < 1.

The methylhydrogen polysiloxanes B-2 are preferably linear. At least half of the D-units preferably have hydrogen atoms bound directly to the silicon ((H (CH ₃ ) SiO groups). Preferably, the number of groups containing hydrogen atoms directly bound to silicon is between 70 and 85% of the difunctional units.

The molar proportion of the hydrogen atoms bonded directly to the silicon atom in component B-2 can be chosen arbitrarily within the above structural constraints.

In component B-2, the molar proportion of hydrogen atoms bonded directly to the silicon atom is preferably between 0.01 and 17 mmol, particularly preferably between 0.1 and 17 mmol and very particularly preferably between 1 and 17 mmol / g of component B-2.

Examples of components B-2 are compounds of formula

M ^H 2D ₁₀ , M ₂ D ₁₀ D ^h 10, M ^h 2D ^h 20D ₀ i, M ^knows 2D ^H ha and / or M2D ^VI 3D ^H 8, where

M ^H = H (CH ₃ ) ₂ SiO _1/2 a

D ^h = H (CH ₃ ) SiO _2/2 .

Preferably, the components B-1 and B-2 in the aqueous emulsion B are in an amount ratio such that the molar ratio of the hydrogen atom directly bound to the silicon atom (SiH) in component B-2 to the unsaturated residues (Si-vinyl) in component B- 1 is between 0.05 and 20, particularly preferably between 0.5 and 10 and very particularly preferably between 1 and 3.

Emulsion B may further comprise an organopolysiloxane which contains units of the general formula (R ⁷ ) 3 10, 4, 10 (VIII) where

R ^{7 is} monovalent, saturated, optionally substituted with hydrocarbon radicals of up to 10 carbon atoms from the group substituted and

31330 / H unsubstituted alkyl, aryl and aryl groups which may be the same or different within the molecule, r integers between 0 and 3

Preferably, the organopolysiloxane is a linear polydimethylsiloxane terminated with trimethylsiloxyl groups such as supplied by Bayer AG under the designation Baysilane®-Ile M. It is particularly preferred to use Baysilane®-Ile M with a viscosity between 50 mm ² s ^-1 and 5,000 mm ² s. ' ¹ .

Emulsion B further comprises a platinum group catalyst, preferably platinum, rhodium, iridium, nickel, ruthenium and / or palladium catalysts, elementally, on a carrier or in the form of their compounds. Preferred are platinum compounds or platinum complexes such as hhPtCle, platinum-olefin complexes, platinum-alcohol complexes, platinum-vinyl siloxane complex, or else elemental platinum on a carrier such as activated carbon, alumina or silica. Particularly preferred as the catalyst is the platinum-vinylsiloxane complex. These platinum-vinylsiloxane complexes preferably have at least two olefinically unsaturated double bonds in siloxane. Such complexes are described, for example, in US-A 3,715,335.

The term siloxane includes polysiloxanes, for example also vinyl polysiloxanes.

The proportion of catalyst, based on the sum of all components, is preferably between 1 and 1000 ppm, particularly preferably between 1 and 500 ppm and very particularly preferably between 25 and 250 ppm.

For example, the platinum group catalyst can also be pre-dissolved in a portion of polymer B-1.

Emulsion B may further comprise an inhibitor, suitable emulsifiers, thickeners and / or conventional additives and excipients (but no fillers). In the other details for the production of emulsion B, reference is made to EP-A 0 819 735.

Aqueous colloidal silicic acid

The aqueous colloidal silicic acid is an aqueous colloid containing 15 to 40% by weight, preferably 25 to 35% by weight, of silicic acid with a mean particle diameter of 6 to 50 nm, preferably 7 to 50 nm.

31330 / H nm. Such colloidal silicic acid systems are known to those skilled in the art and commercially available.

The emulsion of the release agent according to the invention comprises 5 to 35% by weight, preferably 8 to 24% by weight, of the silicone emulsion A or B described above, and 0.5 to 5% by weight, preferably 0.8 to 4% by weight of the aqueous colloidal silicic acid described above. , based on all the emulsion

The total silicone content of the release agent according to the invention is 2 to 20% by weight, preferably 5 to 15% by weight, based on the release agent.

In addition, the emulsions according to the invention may independently contain antifungals or anti-rot (bactericides), wetting agents, thickeners, stabilizers and emulsifiers, antifoams, corrosion inhibitors and colorants, preferably organic colorants, in particular UV-activatable colorants.

The emulsion of the invention may comprise

0.01 to 0.1% by weight, preferably 0.03 to 0.06% by weight of conventional antifungal agents,

0.1 and 1% by weight, preferably 0.3 to 0.7% by weight of thickeners / stabilizers, in particular polysaccharides,

0.1 to 2% by weight, preferably 0.3 to 0.6% by weight of wetting agents, preferably non-ionic wetting agents which, when spraying surfaces, cause homogeneous distribution (spraying) by better wetting, 0.5 to 4% by weight, preferably 0 8 to 2% by weight of polyethylene waxes, in particular hard polyethylene waxes having an average particle size of 1 to 9 μηη and a melting point of between 90 and 110 ° C.

0.1 to 4% by weight, preferably 0.3 to 2% by weight, of polytetrafluoroethylene (wax) micropowders, which are known, for example, from DE-A 40 24 565 and which have a molecular weight of between 30,000 and 200,000 and an average particle size of 1 to 20 pm.

Emulsions of the release agents of the invention may be

31330 / H from the individual components can be mixed together by conventional methods known to those skilled in the art.

Ready-to-use emulsions have a viscosity (DIN 53211, Ford 4 mm beaker) of 20 to 80 seconds, preferably 30 to 60 seconds.

The compositions of the invention are preferably used as a separating agent for molding in vulcanization. In this case, the separating means is sprayed onto the heating membrane and / or the inner surfaces of the tire blank prior to the introduction of the bladder into the interior of the tire blank. The amount of release agent applied is between 8 and 50 g / m @ ² , preferably between 11 and 25 g / m @ ^{2, by} spraying the surface. The required amount of sprayed release agent for forming a conventional passenger car tire is 6 to 40 g, preferably 8 to 18 g.

The heater is then introduced into the tire. The heating membrane heats the tire blank and at the same time presses it into the negative mold under high pressure, vulcanizing. Then the heater is removed from the tire again.

The use of the composition according to the invention as a release agent in the above-described tire vulcanization method has the advantage that the heating element is not only easily inserted into the tire blank and removed again, but that air is easily removed from the interstices between the heating element and the inner tire. due to the formation of fine cracks in the forming semi-elastic layer. Enclosed air means defective tires because under the air bubble there is insufficient vulcanization. Moreover, it is advantageous to remove the heater from the vulcanized tire without any problems. Furthermore, in the variable spray program, it is not possible to spray each tire with the release agent compositions of the invention. With regard to the use of silicone components crosslinking under vulcanization conditions, separation on the sidewalls of the tires can be excluded. Further, a portion of the spray is retained on the heater and positively affects the life of the membrane. It is also possible to spray the new heaters with a release agent to facilitate the start of the use of the heaters in the presses.

31330 / H

In principle, the use of the release agent according to the invention not only improves the quality of the tires and their discarding, but also can significantly reduce tire costs and contamination (equipment contamination / waste reduction) as an immediate consequence of the small amount of spray solutions used.

The invention will be explained in more detail in the following examples.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

Prior art release agent formulation - aqueous spray solution dispersion on the interior of tires;

% Si-oil emulsion

Si-oil, viscosity (1-1000 m ² / s)

100-100,000 cSt 5-15%

fillers

Carbon black 1-2%

Mica, talc, a.i. 20-40%

Glycols, wetting agents 10-20%

Water rest

Injected amount per passenger car tire 16-30 g

According to the prior art, an average of 22 g of a spray solution containing about 40 to 60% of the active ingredient (all components except water) is uniformly sprayed into the passenger car tire blank. This corresponds to about 11 g of active substance / tire of a passenger car. If a spray amount of about 25 to 30% is not expected to reach the tire preform, about 8 g of active substance / tire of the passenger vehicle remain. The components listed below in g / g of the passenger car tire meet the following requirements:

31330 / H

spheroidized Removal from mold Active substances g / blank personal tires slide effect odvzdušne- not separation / slip effect Durability to membrane Si-oil about 0.96 X X X glycols + surfactants about 1.44 X X X Minerál.plnivá + soot about 5.6 X Pretty about 8.0

The following ingredients were used in the following experiments:

Proxel® GXL is a bactericide (a commercial product of ICI).

Kelzan® D is a polysaccharide that acts as a thickener and stabilizer (a commercial product of Langer & Co.).

Levasil® 200A30 (commercial product of Bayer AG) is a silica sol with 30 wt. silica and a specific surface area of 200 m ² / g. Levasil® 200A30 induces better curing in the formulation and contributes to the formation of cracks in the coating when stretched, which again has a positive effect on the venting.

Lanco® Wachs PEW 1555 (commercial product of Langer & Co.) is a hard polyethylene wax with an average particle size of 2.5 μητι, melting point 102 ° C.

Rewopal® LA 6 (a commercial product of Rewo) is a non-ionic wetting agent that provides a homogeneous distribution (spray image) by better spreading the mixture on the inner profile when spraying.

The oil emulsion 1 (cf. example 1) is Baysilon® N (Bayer AG).

The oil emulsion 2 (cf. Example 2) is Baysilon® VP Al 3632 (Bayer

AG).

The oil emulsion 3 (cf. Example 2) is Baysilon® VP Al 3628 (Bayer

AG).

The oil emulsion 4 (cf. Example 2) is Baysilon® N (Bayer AG).

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Example 1

Experiment with condensation crosslinking system

ingredients % by weight Water 83.10 ProxeT GXL (mildew remover) 0.05 Kelzan® D (Thickener) 0.45 Rewopal® LA 6 (emulsifier) 0.40 Oil emulsion 6.50 Oil emulsion 2 6.50 Lanco® PEW 1555 1.00 Levasir 200 A 30 2.00

In the experiments with the formulations of Example 1, about 13 g of product are sprayed. The content of active substance (percentage of all ingredients in the formulation except water) is about 10%. Taking into account a spray amount of about 25 to 30%, about 1.0 g of active substance / tire blank remains.

spheroidized Removal from mold Active substances g / blank personal tires slide effect odvzdušne- not separation / slip effect Durability to membrane Si-polymers 0.8 X X X X surfactants 0.2 X X X Pretty 1.0

In a tire factory, about 3000 pieces of passenger car tires of all sizes were produced in a trial production using a system according to the invention that cross-links with condensation. All vulcanized tires were of the best quality.

It is necessary to emphasize the full transparency of the inside of the tire, which makes it possible to recognize the markings (eg bar code). No defects or other deficiencies were found even if it could be oversprayed.

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The Si-polymers form a very thin layer which polymerizes when vulcanized, thereby disrupting the separation effect somewhat (non-splice separation). This effect is proven by load tests according to DIN 53 539.

The deaeration function, which is otherwise achieved in the prior art filler systems by the presence of a filler, is ensured in the case of the systems according to the invention which crosslink by condensation formed by the layer.

Comparison of injected quantity / tire for passenger car

Inner tire injection solution (solids injected amount / tire blank) for passenger car) According to the state of the art Preparation according to Example 1 solids / preform passenger tires solids / preform passenger tires about 11 g about 1.0 g Si-O / blank passenger tires Si-polymer / blank passenger tires about 1.32 g about 0.8 g

The proportion of solids that must be sprayed on the tire stock to achieve the desired effect is reduced by about 90% (from 11 g to 1.0 g). Comparing the Si-oil and the Si-polymer fraction, there is a reduction of about 40% (from 1.32 to 0.8 g).

This means that the water loading by spraying (spraying is about 25 to 30% of the total spray amount) in the spraying apparatus is reduced to the indicated amount (<90% total, <40% Si-oil-polymer), i.e. in the same ratio the pollutant load is reduced.

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Example 2

Experiment with Pt catalysed addition systems

ingredients % by weight Water 77.05 Proxel® GXL 0.05 Kelzan® D 0.5 Rewopal® LA 6 0.4 Oil emulsion 3 9.5 Oil emulsion 4 9.5 Lanco® PEW 1555 1.0 Levasil® 200 A 30 2.0

About 200 common-size passenger car tires were sprayed and vulcanized. These results correspond to those obtained with condensation crosslinking systems. The tires were of the best quality.

These examples show unequivocally that with the crosslinking silicone systems according to the invention, better results can be achieved with the use of smaller amounts of active substances compared to the prior art separation systems.

Claims (13)

A mold release agent comprising in an aqueous emulsion a system comprising at least two silicone components reacting with each other crosslinking, the system being selected from the group consisting of (A) silicone components reacting with each other under condensation or (B) silicone components reacting with each other by addition and aqueous colloidal silicic acid (silica sol) The mold release agent according to claim 1, characterized in that the condensation-reactive silicone component system (A) comprises a Si-OH-terminated polydimethylsiloxane (A1) and a cross-linked silicone (A2) in the aqueous emulsion. The molding release agent according to claim 1, characterized in that the system (B) of the addition-reactive silicone components comprises an organopolysiloxane (B1) having at least two unsaturated hydrocarbon groups and methyl hydrogen polysiloxane (B-2) in the aqueous emulsion. A mold release agent according to any one of claims 1 to 3, characterized in that it contains 15 to 40 wt. aqueous colloidal silicic acid referring to a silica sol, a silicic acid having an average particle diameter of 6 to 50 nm. A mold release agent according to any one of claims 1 to 3, characterized in that it comprises - 5 to 35 wt. emulsions of silicone components (A) with each other Condensation reacting 31330 / H or silicone components (B) reacting with each other and 0.5 to 5% by weight of aqueous colloidal silicic acid (C), each based on the total amount of mold release agent. A mold release agent according to any one of claims 1 to 5, characterized in that it additionally comprises components selected from the group consisting of antifungals, antifouling agents, wetting agents, thickeners, stabilizers, antifoams, corrosion inhibitors and colorants. Method for vulcanizing air tires, characterized in that a mold release agent as defined in one or more of claims 1 to 6 is applied to the heating membrane and / or the tire preform. Method according to claim 7, characterized in that the application is carried out by spraying or painting. Method according to claim 7 or 8, characterized in that the applied amount of mold release agent is 5 to 50 g / m ² . Use of a composition comprising, in an aqueous emulsion, a system comprising at least two silicone components reacting with each other with crosslinking, the system being selected from the group consisting of (A) silicone components reacting with each other under condensation or (B) silicone components reacting with each other with addition and aqueous colloidal silicic acid. as a mold release agent. 31330 / H Use according to claim 10 in the manufacture of air tires. Use according to claim 11 for coating the heating membrane and / or the inner profile before vulcanizing the tire blank. Use according to any one of claims 10 to 12 in an amount of 8 to 50 g / m ^{2 of} surface to be coated.