DE102015200520A1 - Surface modified bladder for molding a tire - Google Patents

Abstract

The invention relates to a method for the surface treatment of a bladder (14). The bladder (14) has, at least partially, a rubber surface with which a green tire can be vulcanized and formed in a heating chamber or heating mold. This rubber surface is saturated with halogen atoms. Such a halogenated rubber surface does not adhere to the green tire. At the same time, the halogen atoms adhere very well to the bladder (14). The halogenation of the rubber surface can be done directly by supplying an elemental halogen substance on the rubber surface of the bladder (14). The elemental halogen substance can be generated beforehand in a plasma chamber (31).

Description

The invention relates to a method for the at least partial surface modification of an at least partially made of rubber bladder for molding a tire from a green tire. The invention further relates to such a bladder for molding a tire from a green tire.

The molding of tires, in particular motor vehicle tires, takes place in heating chambers or heating molds. In such a heating chamber or such Heizform a "green tire", which consists essentially of several rubber layers inserted. The green tire is not vulcanized. The green tire is transferred in the heating chamber or heating mold in its final form and vulcanized. For this purpose, a bladder ("Bladder") is introduced into the interior of the green tire. In the bladder hot water or hot steam is introduced under high pressure, so that the bladder expands and presses the green tire in its final form. To allow this expansion of the bladder, the bladder is at least partially made of vulcanized rubber.

When expanding the bladder, it may come to an undesirable sticking of the rubber of the bladder with the rubber of the green tire. Such sticking can be prevented if a release agent, for example made of silicone or talc, is introduced between the bladder and the green tire. However, such a release agent has the disadvantage that it must be removed after the formation of the tire by consuming washing steps again. Furthermore, such a release agent complicates the attachment of sensors inside the tire.

From the WO 2009/034901 A1 It has become known to treat a bladder with a plasma flame and then coat with a release agent.

The US 5,728,311 A discloses to use a bladder with a modified rubber compound.

Furthermore, it is from the US 2014/0087067 A1 It has become known to treat a steel plate for molding rubber products with a plasma flame.

To avoid a release agent is in the WO 2011/160939 A1 proposed to subject the bladder to a direct plasma treatment. Here, the bladder is placed in a plasma chamber. Subsequently, a fluorine-containing gas is introduced into the plasma chamber and ignited a plasma. In the known method, the surface of the bladder is covered with a fluorine-containing polymer layer. Such a fluorine-containing polymer layer is also referred to as a "Teflon layer". The fluorine-containing polymer layer serves to separate the bladder from the inside of the green tire. However, such a fluorine-containing polymer layer does not adhere permanently to the bladder itself. In other words, such a polymer layer is subject to wear.

The object of the present invention, in contrast, is to provide a bladder which is particularly economical to use.

This object is achieved by a method according to claim 1. Claims 2 to 8 denote preferred variants of this method.

• a) Einbringen des Heizbalgs in eine Reaktionskammer;
• b) Einleiten eines Behandlungsstoffes in die Reaktionskammer, wobei in der Reaktionskammer kein Plasma auf der Oberfläche des Heizbalgs gezündet wird und wobei der Behandlungsstoff einen halogenhaltigen Reaktionsstoff aufweist, der in Form eines elementaren Halogenstoffes vorliegt oder in der Reaktionskammer zumindest teilweise selbstständig zu einem elementaren Halogenstoff zerfällt;
• c) Zumindest teilweise Verbindung des elementaren Halogenstoffes mit der Oberfläche des Heizbalgs; gelöst.

The object is thus achieved according to the invention by a method for at least partial surface modification of an at least partially made of rubber bladder for molding a tire from a green tire with the method steps:

• a) introducing the bladder in a reaction chamber;
• b) introducing a treatment substance into the reaction chamber, wherein in the reaction chamber, no plasma is ignited on the surface of the bladder and wherein the treatment agent comprises a halogen-containing reactant, which is in the form of an elemental halogen substance or at least partially decays independently in the reaction chamber to an elemental halogen substance ;
• c) at least partially connecting the elemental halogen substance with the surface of the bladder; solved.

The bladder is thus treated prior to its application for molding a tire in a reaction chamber. In the reaction chamber, a treatment substance is introduced. The treatment substance comprises a halogen-containing reaction substance. The treatment substance is in the form of an elementary halogen substance, ie in the form of elemental fluorine, chlorine, bromine, iodine or astatine. Alternatively, the treatment substance comprises a reaction substance which decomposes at least partially independently in the reaction chamber to an elementary halogen substance, ie to fluorine, chlorine, bromine, iodine or astatine. As such a reactant, for example, oxygen difluoride (OF ₂ ) and / or chlorine dioxide (ClO ₂ ) can be used. The treatment substance may comprise further substances, for example an inert gas as the carrier gas.

The treatment substance may be in the form of a liquid. Furthermore, the Treating agent include a solvent, in particular water, wherein in the solvent of the reactant or the elemental halogen substance is dissolved.

With the method according to the invention at least the part of the bladder is treated in the reaction chamber, which comes into contact with the tire during the molding of the tire. By introducing an elemental halogen substance or a reaction substance which at least partially decomposes into an elemental halogen substance, into the reaction chamber, a surface modification occurs on the treated part of the surface of the bladder. More specifically, on this part of the treated surface, hydrogen atoms of the bladder rubber are replaced by halogen atoms. In other words, the surface of the bladder is at least partially halogenated. An additional layer is not applied to the treated part of the surface of the bladder.

The treatment of the bladder in the reaction chamber is preferably carried out at a temperature of -200 ° C to + 400 ° C, in particular at a temperature of -100 ° C to + 200 ° C, preferably at a temperature of 0 ° C to + 100 ° C.

If the elementary halogen substance is chlorine, bromine or iodine, the elemental halogen substance is mainly attached to carbon double bonds of the bladder rubber. If the elementary halogen substance is fluorine, then this elementary halogen substance predominantly replaces hydrogen atoms of the rubber surface of the bladder.

The halogen atoms adhere very well to the treated part of the rubber surface of the bladder. The bladder can thus be reused very often, without having to use a release agent and without having to make a regular plasma treatment of the bladder.

Since fluorine of all halogens has the highest electronegativity and is therefore particularly reactive, it is particularly preferred to use elemental fluorine as the reactant for surface modification of the bladder.

The treatment in the reaction chamber may be carried out under reduced pressure, i. at a pressure in the reaction chamber of less than 1 bar, are performed.

Alternatively, the treatment of the bladder in the reaction chamber at 1 bar or more than 1 bar can be performed.

If the treatment is carried out at overpressure, the surface modification is very fast.

The reactant can be prepared by thermal and / or electrical decomposition of an input material prior to introduction into the reaction chamber.

Elemental halogens, especially elemental fluorine, can be stored only with a high level of security. Particular preference is therefore given to using a chemically stable input substance which is at least partially decomposed into the reaction substance in a plasma before it is introduced into the reaction chamber. The plasma decomposition does not take place in the reaction chamber, but in front of the reaction chamber. Since the plasma does not burn directly on the surface of the bladder, a connection of nitrogen, carbon and / or oxygen-containing compounds can be avoided. Thus, preferably only "downstream sources" are used.

In addition to the safe storage option, this approach offers the further advantage that the reagent is activated in the plasma. A reactant which is decomposed in a plasma only shortly before it is introduced into the reaction chamber is therefore more reactive than an elementary halogen substance introduced into the reaction chamber. The surface modification of the bladder rubber surface in this case is particularly thorough.

In a particularly preferred embodiment of the invention, at least one nitrogen halide is used as the input material. Nitrogen halides are readily storable and can be decomposed in a plasma just prior to their application to the bladder in the plasma to a reactive elemental halogen substance. Particular preference is given to using nitrogen trifluoride (NF ₃ ).

The surface modification of the bladder can be done in a separate reaction chamber. Such surface modification is referred to as offline treatment. Alternatively or additionally, the surface modification of the bladder may be applied directly in the heating mold for molding the tire. Such surface modification is referred to as inline treatment. In the case of an inline treatment can be dispensed with the construction of a separate reaction chamber.

Here, a heating chamber or heating mold can be used, which is designed in the form of an autoclave.

Particularly preferably, the bladder is treated in the reaction chamber in an expanded state. In this way it can be ensured that the entire extended surface of the bladder is provided with halogen atoms and does not adhere to the interior of the tire auszuformenden. The expansion of the bladder can be done hydraulically, pneumatically and / or mechanically.

The object of the invention is further achieved by a bladder for molding a tire from a green tire with the features of claim 10, wherein the bladder has an at least partially engageable on the inside of a tire bladder rubber and the surface of the bladder at least partially an immediately halogenated Rubber surface has.

As stated at the outset, such a bladder with an immediately halogenated rubber surface can be used many times, in particular 50 to 100 times, without the bladder sticking to the inside of the tire and without the need for a release agent.

The bladder can be made entirely of rubber. Alternatively, the bladder may have a bladder body bounded on at least one end by a plate.

Particularly preferably, the surface of the bladder according to claim 11 at least partially an immediately fluorinated rubber surface.

At least the part of the surface of the bladder body has an immediately halogenated rubber surface which comes into contact with the green tire when forming the tire.

Further features and advantages of the invention will become apparent from the following detailed description of several embodiments of the invention, with reference to the figures of the drawing, which shows essential to the invention and from the claims.

The features shown in the drawing are shown such that the features of the invention can be made clearly visible. The various features may be implemented individually for themselves or for a plurality of combinations in variants of the invention.

Show it:

1 a schematic representation of a heating chamber or mold for molding a tire by means of a bladder;

2 a schematic representation of an apparatus for surface modification of a bladder;

3 a schematic representation of the surface of a bladder before and after a surface modification;

4 a schematic representation of the surface of a bladder according to 3 after surface modification;

5 a schematic representation of an alternative device for surface modification of a bladder;

6 a schematic representation of an alternative device for surface modification of a bladder;

7 a schematic representation of the surface of a bladder after a surface modification according to the prior art; and

8th a schematic representation of the surface of a bladder according to an alternative surface modification according to the prior art.

1 shows a heating chamber or heating mold 10 for molding a tire. In the heating chamber or heating mold 10 is a green tire 12 inserted. The green tire 12 consists essentially of several layers of unvulcanised rubber. The green tire 12 is by means of a bladder 14 against an inner wall 16 the heating chamber or heating mold 10 pressed. The bladder 14 For this purpose, hot steam at a temperature of 150 ° C to 160 ° C is applied. In this shaping of the green tire 12 this is both pressed into its final form as well as vulcanized. To the bladder 14 Being able to reuse as often as possible is the surface of the bladder 14 modified with the method according to the invention.

2 shows a device 18 for modification of the surface of the bladder 14 , The bladder 14 is located in a reaction chamber for its surface modification 20 , The reaction chamber 20 has no means for igniting a plasma. The reaction chamber 20 includes an inlet 22 and an outlet 24 , The reaction chamber 20 is over the outlet 24 with a pump 26 connected. About the outlet 24 or the pump 26 can the pressure in the reaction chamber 20 be set. When treating the bladder 14 may be a negative pressure or atmospheric pressure in the reaction chamber 20 available. Preferably, there is an overpressure in the reaction chamber 20 before, so that the modification of the bladder 14 particularly effective.

About the inlet 22 becomes a treatment substance 28 in the reaction chamber 20 initiated. In the present case, the treatment substance sets 28 composed of nitrogen (N ₂ ) and fluorine (F ₂ ). The treatment substance 28 is in gaseous form. Alternatively, the treatment agent 28 also in the form of a liquid or a solid in the reaction chamber 20 be initiated. The nitrogen content of the treatment substance 28 does not contribute to the surface modification of the bladder 14 in the reaction chamber 20 in, since the nitrogen content of the treatment substance 28 largely inert and very inert. The treatment substance 28 also has a halogen-containing reactant 29 in the form of an elemental halogen substance, namely in the form of fluorine (F ₂ ). By the fluorine, ie the reactant 29 , the surface of the bladder becomes 14 modified, more precisely halogenated.

An input material 30 was before entering the reaction chamber 20 in a plasma chamber 31 in the treatment substance 28 decomposed. The plasma chamber 31 has an electrode for this purpose 32 on, over a voltage source 34 is supplied with voltage. The voltage source 34 may be in the form of a DC voltage source, a high frequency generator, an induction coil or a magnetron. When the voltage source 34 is formed in the form of an induction coil or a magnetron, can be applied to the electrode 32 to ignite the ignition of the plasma. In the latter case, the magnetron may be connected to an antenna (not shown) to emit electromagnetic radiation to ignite the plasma into the plasma chamber 31 initiate. In any case, in the plasma chamber 31 a plasma to decompose the input material 30 ignited. For the production of the decomposed treatment substance 28 becomes an input material 30 in the form of a nitrogen halide, in the present case nitrogen trichloride (NF ₃ ), into the plasma chamber 31 initiated. The nitrogen halide is passed through a bottle 36 provided.

Alternatively to the in 2 shown device 18 can be a treatment substance 28 also directly, ie without the interposition of the plasma chamber 31 in the reaction chamber 20 be initiated.

For example, in the reaction chamber 20 directly a mixture of an elemental halogen material, in particular fluorine, and a carrier gas, for example nitrogen, in the reaction chamber 20 be initiated.

3 shows a section of the surface of the bladder 14 before its surface modification (left) and after its surface modification (right) in the reaction chamber 20 (please refer 2 ). The surface 38 the bladder 14 consists essentially of an elastomer in the form of rubber, as in 3 simplified as indicated by C atoms. Before surface modification, these C atoms are saturated to the outside by hydrogen atoms (H atoms) (left). As from the right part of 3 As can be seen, the hydrogen atoms are replaced by halogen atoms (R) in the surface modification. The halogen atoms may be fluorine, iodine, chlorine and / or bromine atoms. As a result, an adhesion of the bladder 14 on the green tire 12 (please refer 1 ) prevented. The surface modification of the bladder 14 takes place preferably in the expanded state of the bladder 14 , so that as far as possible all hydrogen atoms are replaced by fluorine atoms.

Preferably, the occupancy with halogen atoms, in the present case with fluorine atoms, is monitored by means of a Fourier transform infrared (FTIR) spectrometer.

4 shows a more concrete representation of the 3 , being out 4 it becomes apparent that the surface 38 the bladder 14 after treatment with F ₂ and / or NF ₃ to the outside almost completely saturated with F atoms. An additional layer on the surface 38 was not deposited. As a result, a very adherent functionalization is achieved, the virtually no liability to rubber, ie no liability to green tires 12 (please refer 1 ) having.

5 shows an alternative device 18 for the treatment of a bladder 14 , Unlike the in 2 shown device 18 has the device 18 according to 5 a reaction chamber 20 on, passing through a grid 40 in a plasma chamber part 42 and a plasma-free chamber part 44 is divided. The bladder 14 is in the plasma-free chamber part 44 arranged.

6 shows another alternative device 18 , which - in adaptation to the shape of the bladder 14 - Is formed largely rotationally symmetrical. The device 18 has a central outlet 24 up, fluidly with a pump 26 connected is. About an inlet 46 becomes the input material 30 initiated. In a reaction chamber 20 separates a grid 40 a plasma chamber part 42 from a plasma-free chamber part 44 in which the bladder is 14 is arranged. The plasma is between an electrode 32 and the grid 40 through a voltage source 34 ignited. The voltage source 34 can - as well as the Voltage source according to the device 18 in 5 - Analogous to the voltage source according to the device 18 in 2 be educated.

To illustrate the difference of the present invention to methods and apparatus according to the WO 2011/160939 A1 , is in 7 a bladder 14 ' represented, its surface 38 ' directly plasma treated with NF ₃ . This indicates the surface 38 ' many bindable radicals, resulting in a relatively good adhesion to the rubber of a green tire 12 (please refer 1 ) arises.

8th shows a bladder 14 ' whose surface 38 ' also according to the WO 2011/160939 A1 was treated. In the case of bladder 14 ' according to 8th was the bladder 14 ' plasma-treated with CF ₄ gas. This results in the surface 38 ' the bladder 14 ' an additional layer, although a low adhesion to the rubber of the green tire 12 (please refer 1 ), but also easily peels off, so that the bladder 14 ' relatively often needs to be re-treated.

In summary, the invention relates to a method for surface treatment of a bladder. The bladder has at least partially a rubber surface with which a green tire in a heating chamber or heating mold can be vulcanized and formed. This rubber surface is saturated with halogen atoms. Such a halogenated rubber surface does not adhere to the green tire. At the same time, the halogen atoms adhere very well to the bladder. The halogenation of the rubber surface can be done directly by supplying an elemental halogen substance on the rubber surface of the bladder. The elemental halogen substance can be generated beforehand in a plasma chamber.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2009/034901 A1 [0004]
• US 5728311 A [0005]
• US 2014/0087067 A1 [0006]
• WO 2011/160939 A1 [0007, 0055, 0056]

Claims (11)

Process for the at least partial surface modification of a bladder (at least partially made of rubber) ( 14 ) for molding a tire from a green tire ( 12 ) with the process steps: a. Inserting the bladder ( 14 ) in a reaction chamber ( 20 ); b. Introduction of a treatment substance ( 28 ) in the reaction chamber ( 20 ), wherein in the reaction chamber ( 20 ) no plasma is ignited on the surface of the bladder and wherein the treatment substance ( 28 ) a halogen-containing reactant ( 29 ), which is in the form of an elemental halogen substance or in the reaction chamber ( 20 ) decomposes at least partially independently to an elemental halogen substance; c. At least partial connection of the elemental halogen substance with a surface ( 38 ) of the bladder ( 14 ). Process according to claim 1, wherein as reaction substance ( 29 ) elemental fluorine is used. Process according to claim 1 or 2, wherein the pressure of the treatment substance ( 28 ) in the reaction chamber ( 20 ) is less than 1 bar. Process according to claim 1 or 2, wherein the pressure of the treatment substance ( 28 ) in the reaction chamber ( 20 ) Is 1 bar or more than 1 bar. Method according to one of the preceding claims, wherein an input material ( 30 ) before being introduced into the reaction chamber ( 20 ) in a plasma at least partially into the reactant ( 29 ) is decomposed. Process according to claim 5, wherein as input material ( 30 ) at least one nitrogen halide, in particular NF ₃ , is used. Method according to one of the preceding claims, wherein a heating chamber or mold for forming the tire is used as the reaction chamber. The method of claim 7, wherein the heating chamber or heating mold is in the form of an autoclave. Method according to one of the preceding claims, wherein the bladder ( 14 ) in the reaction chamber ( 20 ) in an inflated state. Bladder ( 14 ) for molding a tire from a green tire ( 12 ), wherein the bladder ( 14 ) has a bladder body made of rubber, which can be applied at least partially to the inside of a tire, characterized in that the surface ( 38 ) of the bladder body has at least partially an immediately halogenated rubber surface. Bladder ( 14 ) according to claim 10, wherein the surface ( 38 ) of the bladder body has at least partially an immediately fluorinated rubber surface.

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