CS224599B1 - Self-vulcanizing rubber mixture - Google Patents

Description

The invention relates to a composition of a self-vulcanizing rubber composition suitable for the production of waterproofing films used in construction. The rubber waterproofing films that are currently commercially available are made from rubber blends containing all the necessary ingredients (rubber, fillers, emollients, vulcanization activators and accelerators, vulcanizing agent such as sulfur) by high temperature vulcanization on a rotary press or autoclave. Mixing of the mixtures is usually carried out on a cooled kneading machine, mixing of the vulcanizing agent after accelerators and then on a double-roll at low temperatures so as to avoid vulcanization. The rubber mixture is further processed to the required shape and size of the film, usually by rolling at temperatures of 40 - 80 ° C, it is wrapped in a separating textile insert before vulcanization, before the vulcanization the film can be doubled.

The disadvantages of the above-mentioned processes in the production of rubber foils are, besides considerable labor, a highly energy-intensive vulcanization process and low labor productivity. The compositions prepared by the above process, and in particular the composition thereof, do not allow them to be used in the unvulcanized state for a given application. The disadvantage is very low mechanical strength of the foil (tensile strength 0.5-2 MPa), the foil is soft, has a cold flow, does not resist mechanical stress, it cannot be freely manipulated during application - it must be stored in a textile wrap insert. Last but not least, a vulcanizing system suitable for self-vulcanizing compositions has not been proven to guarantee high processing safety and, on the other hand, when exposed to a weather film (application) it was effective enough to vulcanize the film at room temperature in a short time.

U.S. Pat. Nos. 3,835,201, 4,031,169, 4,036,912 and 4,046,840 disclose a composition of some unvulcanized

224,599 EPDM-based mixtures with polyplephins suitable for technical products such as car dashboards, etc. Mixtures require high processing temperatures, but the physico-mechanical properties of these materials are still low, in particular ductility and dynamic properties (unvulcanized thermoplastic).

These drawbacks are overcome by the subject of the invention, which is a self-vulcanizing rubber composition for waterproofing membranes characterized in that it contains 18 to 45 wt. % of ethylene-propylene terpolymer or a combination thereof with butadiene-styrene rubber and butyl rubber having a molecular weight of 100,000 to 700,000; % polyethylene or copolymers thereof with vinyl acetate having a molecular weight of 20,000 to 50,000, 15 to 50% by weight; % of inorganic fillers, 0.03 to 2 wt. % stearic acid, 0.1 to 5 wt. % zinc oxide and 0.1 to 5 wt. % of the fact, wherein the mixture may contain 2 to 3θ wt. % of plasticizers or extenders, it is preferred that the vinyl acetate content of the copolymers is 6 to 35 wt. %.

The subject of the invention is a composition of a self-vulcanizing rubber composition suitable for the production of waterproofing films. The mixture is prepared by mixing the rubber component, inorganic fillers and plastic component in the presence of zinc oxide, stearic acid and factis in a kneading machine. It has been discovered that said components are brought into active form by initiation by heating to a high temperature, the minimum temperature of the mixture at the end of stirring being 170 ° C. The decisive condition for the preparation of the compositions according to the invention is the presence of factis as a substance capable of slowly releasing sulfur upon activation by high temperature. The reaction rate and the total vulcanization time depend on the fact of the fact in the mixture. The addition of vulcanization activators (zinc oxide, stearic acid) serves to achieve the full degree of vulcanization. The vulcanization of the mixture then proceeds slowly after mixing, cooling and weathering itself. Physico-mechanical values are gradually increasing, significantly dynamic properties, final values can be achieved in 3 to 6 months of natural weathering.

The chemistry of the reaction is a complex process, probably explained as a series of oxidation-reduction reactions (between releasing sulfur, oxygen and rubber) that are the source of free radicals initiating cross-linking reactions. Sulfur probably binds in the form of cyclic polysulfides. In addition, oxygen and high temperature (tearing of the chains of molecules) also act

224 599 rubber), secondary bonds rubber - filler. The process may also affect the type of plasticizer or extender used, in particular the presence of components containing unsaturated compounds.

Another advantage is that the blended composition has a high safety and can be stored for a longer period of time without the risk of vulcanization. Due to some content a plastic film component can be applied immediately after rolling, fo ^of lie is self-supporting, characterized by adequate stiffness and hardness sufficient for handling the application, it is not necessary to interleave the separating pad against sticking. The processing temperatures are somewhat higher (80 - 120 ° C) than the conventional rubber compound due to the plastic component content, higher processing temperatures due to the risk of vulcanization also exclude the use of known vulcanizing systems usually used for similar types of mixtures.

It has been found that, in particular, rubbers having a high saturation are particularly suitable for the preparation of the compositions according to the invention, in particular ethylene-propylene terpolymer and butyl rubber. Diene rubbers or copolymers thereof are also suitable for certain applications where the maximum weathering resistance of the materials is not required, but combinations of the rubbers are suitable from the technical point of view.

The properties of mixtures, processability and price can be adjusted as usual in rubber industry by plasticizers (mineral oils), extenders (asphalt, resins) or other auxiliaries. Upon reaching the full degree of vulcanization, the mixtures are irreversibly crosslinked and cannot be reprocessed.

Example 1

Mixtures according to formulas 1, 2 and 3 were mixed in a high pressure mixer of the Werner and Pfleiderer type with a working chamber content of 180 l. The kneading machine was overfilled by 10% of its volume. After seven minutes, stirring was terminated, the temperature at which the mixture was discharged at the temperature sensor was 180 ° C. The films were rolled from the mixtures at 120 ° C, from which the test specimens were punched and the basic mechanical properties determined.

- 4,224,599

Used recipe 1 wt. % ethylene-propylene terpolymer 26 butadiene-styrene rubber 9 faktis 2.6 asphalt 1.6 soot 50 polyethylene 5 mineral oil 3.6 stearic acid 0.6 zinc oxide 1.6

Used recipe 2 wt. % ethylene-propylene terpolymer 25 butyl rubber 10 factis 4 asphalt 4 kaolin 20 carbon black 20 ethylene-vinyl acetate with vinyl acetate content 13% by weight 15 stearic acid 0.5 zinc oxide 1.5

Used recipe 3 wt. % ethylene-propylene terpolymer 25 factis 5 soot 30 coumarone resin 2 polyethylene 35 stearic acid 1 zinc oxide 2

- 5 Basic mechanical properties of mixtures 224 599

(a) after mixing

Tensile strength / MPa / recipe 1 7,2 recipe 2 6.5 recipe 3 7,9 Module 200% / MPa / 6.4 5.1 6.6 Ductility /% / 420 600 580 Elasticity /% / 21 22nd 20 May Hardness / Sh A / 79 76 80 Elongation /% / 80 120 90

Breaking resistance

De Mattia / cycles / 13 000 8 500 9 300 (b) after 4 months of natural aging recipe 1 recipe 2 recipe 3 Tensile strength / MPa / 9.3 8.3 9.3 Module 200% / MPa / 7.6 6.8 8.1 Ductility /% / 370 520 490 Elasticity /% / 28 25 23 Hardness / Sh A / 81 78 81 Ductility /% / 40 70 60 Breaking resistance De Mattia / cycles / 90 000 36 000 48 000

Example 2

The mixing method and composition according to the recipes were the same as in Example 1. The kneading machine was intensively cooled, the temperature of the mixture at the discharge control was 140 ° C. The film was rolled from the mixture at 120 ° C, from which the test specimens were punched, and after 4 months of natural aging, the basic mechanical properties were determined.

- 6,224,599

Basic mechanical properties of mixtures

Tensile strength / MPa / recipe 1 7,6 recipe 2 7.0 recipe 3 7,8 Module 200% / MPa / 6.4 5.6 6.4 Ductility /% / 390 530 560 Elasticity /% / 21 22nd 21 Hardness / Sh A / 78 77 81 Ductility /% / 98 118 85 Breaking resistance De Mattia / cycles / 12 500 9 200 7 600

The above examples show qualitatively higher effects of the compositions according to the invention.

Claims (3)

A self-vulcanizing rubber composition for waterproofing membranes, characterized in that it contains 18 to 45 wt. % of ethylene-propylene terpolymer or a combination thereof with butadiene-styrene rubber and butyl rubber having a molecular weight of 100,000 to 700,000; % of polyethylene or a copolymer thereof with vinyl acetate having a molecular weight of 20,000 to 50,000, 15 to 50% by weight; % inorganic fillers, 0.05 to 2 wt. % stearic acid, 0.1 to 5 wt. % zinc oxide and 0.1 to 5 wt. % fact. 2. A self-vulcanizing rubber composition as claimed in claim 1 comprising 2 to 30 wt. % of plasticizers or extenders. Third selfcuring rubber composition according to claim 1 and _Z 2 wherein the vinyl acetate content in the copolymer is 6-35 wt. %.