SK117093A3 - Process for producing elastomer corrosion resistant lining foil and the foil produced by this process - Google Patents

Abstract

Prepn of the sheet (I) which is self-vulcanising at elevated temp. without pressure, comprises prepn. of an elastomer mixt. (II) and moulding the mixt. to a sheet. Before and/or during the moulding process, the mixt. is degassed under reduced pressure. Also claimed is corrosion-resistant lining sheet (I) produced by this process.

Description

METHOD OF MANUFACTURE OF CORROSION-RESISTANT ELASTOMER LAYING FOIL AND FOIL MADE IN THIS METHOD

Technical field

The invention relates to a method for producing a corrosion-resistant, unvulcanized, high-temperature, pressure-free self-vulcanized lining elastomeric film by making an elastomeric composition and forming the composition into a film. The invention further relates to an elastomeric lining film produced by the method defined above.

BACKGROUND OF THE INVENTION

Elastomeric lining foils are used to protect metal components from attack by aggressive environments. Corresponding unloadings are found in tanks, tankers, boiler wagons and the like. for protection against acids, alkalis, oils, solutions and solvents.

Since the operation of flue gas desulphurisation plants in black and brown coal-fired power plants, unloadings on the steel surfaces of these plants have been common. The linings are subject to chemical attack, thermal stress and mechanical load. Chemical attack is caused mainly by dissolved soles, gases and water condensates. The thermal stress is between 50 'C and 60 to 70' C under different conditions of use.

The properties and lifetime of the gumming made from the liner film are locally determined both by the rubber and other components of the mixture, as well as by the film production and use.

In practice, natural rubber, isoprene-, chloroprene-, styrene-butadiene, isobutene-, isoprene-, acrylonitrile-butadiene-rubbers and EPDM are generally used predominantly for lining for corrosion protection. Particularly suitable as mounting rubber are diene rubbers containing halogens. Particularly preferred are chlorinated or brominated butyl rubbers which have a slight diffusion and permeation coefficient against water, water vapor, sulfur dioxide, hydrogen chloride and other gases and have good resistance to aggressive environments. Moreover, these rubbers are advantageous because of their thermal mechanical properties of aging as well as their tendency to self-vulcanize.

It is known to use a plurality of starting elastomeric liner films in vulcanization states.

Unvulcanized films of low plasticity and temperature action in the case of flue gases, these unvulcanized films used have the advantage of their production cost. For example, by the effect that they are in use, they cause low deposition, they cure themselves. It turns out that, compared to the vulcanized films used, they have considerable drawbacks in the diffusion and permeability properties, in the mechanical values of the rubberization applied and in the breakdown strength.

To avoid these drawbacks, the liner films have been used in a pre-vulcanized or vulcanized state. This, of course, will increase production costs. For the curing of butyl lining films in autoclaves, a curing time of 90 minutes and a curing temperature of 138 C are typical. In addition, consideration should be given to heating and cooling times. For pre-vulcanization of halogenated butyl grades, heating times of 6 to 10 hours at 100 ° C shall be taken into account irrespective of heating and cooling times. The difficulty in deploying pre-vulcanized films is the difficulty in achieving a reproducible setting of the desired vulcanization state for the necessary large-volume parts (coiled goods).

Furthermore, the use of vulcanized and pre-vulcanized material causes drawbacks in use, such as increased rigidity, deformed coiled goods, and for tack and weldability, leading to deteriorated peel resistance values during gluing. The rubber-metal bond and the rubber-rubber bond prove to be a weak spot for the deposition of vulcanized or pre-vulcanized films.

Attempts have been made to avoid the drawbacks of deposition of unvulcanized and pre-cured films with multi-layered films consisting of a chemically resistant topsheet and a well-adhesive underside. In addition to the increased manufacturing costs, difficulties remain in adjusting the reproducible state of vulcanization of the underside and difficult to use on geometrically complex components.

Thus, the technical problem for the use of liner films is generally that a certain compromise is always necessary, since the advantages achieved are only possible when considerable disadvantages are admitted.

SUMMARY OF THE INVENTION

Accordingly, the invention provides a method for producing a corrosion-resistant, unvulcanized, high-pressure, self-vulcanized unloading elastomeric film under pressure by producing an elastomeric composition and forming the composition onto a film by subjecting the elastomeric composition before and / or during molding to a vacuum degassing of the elastomer mixture.

With this relatively simple measure, it is surprisingly possible to achieve the advantages of using unvulcanized films without having to take into account the disadvantages of the unvulcanized films observed so far. The invention is based on the discovery that the disadvantages observed so far with the use of unvulcanized liner films result in the fact that at the pressure without vulcanization of the unvulcanized film used, the gas bubbles contained in the film expand and thus lead to porosity which substantially compromises the mechanical and electrical properties of the film. This is particularly true for halogenated diene rubbers, in particular chlorinated or brominated butyl rubbers, which, depending on the material, have low diffusion and permeability coefficients and are therefore particularly sensitive to the expansion of gas bubbles.

The evacuation of the elastomeric composition can be carried out in the manufacture of the composition by a circular mixer or mixer and / or during the forming in a vacuum extruder.

The formed elastomeric films are usually applied over the adhesive layer to the metal prepared by the primer and binder. Immediately after application, the usual temperature and medium load present in the apparatus can be performed. Due to temperature and time, the elastomer vulcanizes without pressure, and with respect to the absence of bubbles, without a noticeable increase in volume.

The film produced by the process of the invention combines good application properties and advantages in the bonding and welding capability of the unvulcanized material with excellent aging resistance, chemical resistance and diffusion resistance of bubbles free of halogenated butyl rubbers.

Due to the degassing, the peel resistance values of the rubber-to-metal and rubber-to-rubber connections, including resistance to chemical and thermal influences, and the values of electrical breakdown strength, are significantly above the corresponding values of the non-degassed material.

DETAILED DESCRIPTION OF THE INVENTION

For steel coating rubber was used mixture of the following frame composition in parts by weight: bromobutyl 100 elastomer softener 10 blacks 95 processing aid 5 metal oxide 5 accelerator 5

Following the production of the mixture in the internal mixer, the production of the film (A) on a Rollerhead with degassing unit followed (Extruder: L = 20 d, d = 150 mm, vacuum pump: Q = 630 m / h, vacuum 14 hPa). The film thickness was 4 mm.

For comparison, the film (B) produced without degassing was used.

Mechanical parameters, aging at 70 ° C, deionization (70 ° C), peel resistance and breakdown strength of film (A), (B) (unvulcanized) and film (C) (ungassed, vulcanized at 143 ° C for 90 ° C) are compared. min).

..... Foil A Foil B Foil C Shore A DIN 53 505 57 57 57 Strength (MPa) 8.4 7.8 8.4 Elongation (%) DIN 53 504 Tear resistance 390 440 390 (Graves without cut) (N / mm) DIN 53 515 Aging of unvulcanised foils at 100 ´C, 8 weeks, final strength based on strength, determined after compression heating (90 31.0 27.6 31.0 minutes, 143 ’C) (%) Final elongation related to elongation determined after compression 71 60 73 heating (%) Swelling, 70 ’C, deionization, 72 48 70 12 weeks, volume increase (%) 2.1 13.5 2.1 Weight gain Peel resistance in accordance with DIN 53 531 Vulcanization: 90 minutes 143 ´C 2.9 2.8 2.8 (N / m) 9.8 7.4 5.2 Breakdown voltage (kV / mm) on 4 mm board, A, B unvulcanized, crack in gum Crack in glue C vulcanized 5.7 4.8 4.9 Resistance (Ohm cm) 4.5.10 ¹³ 3 , 5.10 ¹¹ 3,7.10 ¹¹

/ WO-9

Claims (5)

A method for producing a corrosion-resistant, unvulcanized, high-pressure, self-vulcanized unloading elastomeric film under pressure by producing an elastomeric composition and forming the composition onto a film, characterized in that the elastomeric composition is subjected to negative pressure before and / or during molding mixture. 2. The process of claim 1, wherein the elastomeric composition is a halogenated diene rubber. 3. A method according to an elastomeric butyl rubber mixture. Item 2, characterized in that it is chlorinated in that bromine is used or used 4. The method of claim 3, wherein an elastomeric composition having the following parts by weight is used: halogenated butyl rubber 100 elastomer softener 1 - 40 preferentially 10 blacks 10 - 200 preferentially 95 processing aid 0,5- 15, preferentially 5 metal oxide 0,5- 30, preferentially 5 accelerator 1 - 10 preferentially 5 5. A corrosion-resistant elastomeric lining film, characterized in that it is produced by the method of any one of items 1 to 4.