CS261270B1 - Modified synthetic rubber based rubber blend for the production of waterproofing membranes - Google Patents

Abstract

Modified rubber mixture based on synthetic rubber for the production of waterproofing membranes containing, per 100 parts by weight of butadiene-styrene rubber or its mixture with regenerated rubber, 8 to 40 parts by weight of high-pressure polyethylene or its copolymers with vinyl acetate, 20 to 150 parts by weight of rubber crumb or dust, 5 to 25 parts by weight of oxidized asphalt with a softening point above 70 °C, 50 to 150 parts by weight of inorganic fillers or carbon black, 5 to 25 parts by weight of mineral oil, 0.8 to 2.5 parts by weight of stearic acid and 2 to 8 parts by weight of zinc oxide. The rubber mixture may contain, per 100 parts by weight of elastomeric component, 0.4 to 2 parts by weight of sulfur, 0.6 to 1.5 parts by weight of parts of 2-mercaptobenzothiazole and 1 to 4 parts by weight of vulcanization accelerators, which may be tetramethylthiuram disulfide, derivatives of zinc salts of dithiocarbamic acid or zinc 0,0'dibutyldithiophosphate. The waterproofing film made from the rubber mixture according to the invention is made exclusively from domestic raw materials and is intended for the implementation of waterproofing coatings in the field of roof and ground waterproofing.

Description

The invention relates to the composition of a modified rubber mixture based on synthetic rubber suitable for the production of waterproofing films used in waterproofing technology, especially in the construction industry.

Due to the ever-increasing demands of the construction industry for the quantity and quality of waterproofing materials and foils suitable for repairing damaged roofing, there is a need to address this requirement by introducing new types of foil materials with the required properties. Foils should be characterized by good resistance to weather aging, elasticity, resistance to low temperatures and temperatures to which the roof covering is exposed in summer periods. From the manufacturer's point of view, the waterproofing foil should be characterized by minimal demands on the import of raw materials from areas with unfavorable foreign exchange rates, the advantage should be the use of domestic raw materials or secondary raw materials.

Waterproofing foils according to Czechoslovak Patent No. AO 182 416 made on the basis of regenerated rubber, partially regenerated rubber and other additives are characterized by good formability, but the disadvantage is significant dimensional changes of the foil after exposure to weathering. These changes are caused by the high content of regeneration oils, the deficiency is manifested by the peeling of foil joints, the release of foils from the roof sheathing, which results in a gradual loss of function. Waterproofing foil according to No. AO 240 949 made on the basis of SBR, regenerator, rubber crumb and other additives is also characterized by very good formability and waterproofing ability, but the disadvantage is low mechanical properties, especially tensile strength. The deficiency is manifested especially when applying the foil to buildings, when handling and mechanical stress can lead to a violation of the integrity of the foil. The already applied foil has low mechanical resistance and can be damaged, for example, during further finishing work, especially due to dilatation changes in the substrate, when the foil, due to its low mechanical strength, is no longer sufficient to eliminate the mentioned stresses. The foil also cannot be used for external insulation due to its low resistance to permanent deformation and creep resistance (insulation of foundations, etc.).

The above-mentioned shortcomings are eliminated by the subject of the invention, which is a modified rubber mixture based on synthetic rubber for the production of waterproofing films, characterized in that per 100 parts by weight of butadiene-styrene rubber or its mixture with regenerated rubber it contains 8 to 40 parts by weight of high-pressure polyzet;, lene or its copolymers with vinyl acetate, 20 to 150 parts by weight of rubber crumb or crumb, 5 to 25 parts by weight of oxidized asphalt with a softening point of 70 °C, 50 to 150 parts by weight of inorganic fillers or carbon black, 5 to 25 parts by weight of mineral oil, 0.8 to 2.5 parts by weight of stearic acid and 2 to 8 parts by weight of zinc oxide. The rubber mixture may contain 0.4 to 2 parts by weight of sulfur, 0.6 to 1.5 parts by weight of parts of 2-mercaptobenzothiazole and 1 to 4 parts by weight of fast or ultrafast accelerators, which may be tetramethylthiuram disulfide, derivatives of zinc salts of dithiocarbamic acid or zinc 0,0'dibutyldithiophosphate.

The essence of the invention is the composition of a rubber mixture suitable especially for the production of waterproofing films, where the elastomeric component consists of a combination of butadiene-styrene rubber in a mixture with regenerated rubber, modified with high-pressure polyethylene or a copolymer of ethylene with vinyl acetate with a molecular weight of 20,000 to 50,000, rubber dust or crumb and other additives. The addition of a plastic component to the mixture ensures high initial values of the film in the case of a requirement for high film elasticity. When requirements for high film resistance to atmospheric aging are required, the addition of polyethylene-vinyl acetate copolymers is suitable, preferably types containing 6 to 25% by weight of vinyl acetate. The type of rubber crumb or dust can affect the resistance of the mixture to weather aging, satisfactory results were achieved with crumb based on SBR and NR, the best results with crumb based on EPDM. The fineness of the rubber crumb can also affect the processability of rubber mixtures and the quality of the resulting film; crumb with a particle size of up to 0.6 mm is suitable. Oxidized asphalt with a softening point above 70 °C and mineral oil ensure good processing properties of the mixture, favorably affecting the cohesion of the joints of the finished films. The processability of the mixtures can be further improved with commonly used rubber additives such as lubricants, synthetic or natural resins. The resistance to atmospheric aging of the film can be increased by using suitable types of antioxidants and antiozonants such as phenyl-beta-naphthylamine, N-isopropyl-N'-phenyl-p-phenylenediamine, etc.

The addition of vulcanization activators, i.e. stearic acid and zinc oxide to the rubber mixture allows for its gradual partial vulcanization after exposure of the film to atmospheric aging and elevated temperatures. Partial vulcanization during atmospheric aging increases its mechanical properties to a certain extent, especially tensile strength and hardness, has a higher ability to withstand mechanical stress and repeated deformations, partial vulcanization is caused by the gradual migration of sulfur and accelerators contained in the regenerator and rubber crumb and their reaction - crosslinking with the elastomeric component of the mixture. The amount of stearic acid and zinc oxide must be determined experimentally, given the required properties of the film and the different qualities of rubber crumb. By further adding organic accelerators and sulfur to the rubber mixture, it is possible, for example, to produce rubber films characterized by relatively high mechanical properties by classical vulcanization of films in autoclaves. The films are completely vulcanized due to the nature of the elastomeric component, which is characterized by high unsaturation; however, these films are only suitable for use in the field of ground waterproofing.

The preparation of the mixture and the technology for producing the film is simple and consists of mixing all the ingredients in a rubber kneading machine, the vulcanizing additives are mixed on a two-roller, and the film can be rolled to the required size on a three-roller or four-roller.

The waterproofing film produced according to the invention can be used to create waterproofing coatings themselves, as a flexible non-absorbent insert for creating seamless coatings in which it can replace insert materials made of glass mats and fabrics. The product can also reduce the consumption of scarce asphalt strips of type A, R, IPA, Arabit. The film has an elastic: dharakter is pliable and the advantage is that after heating it copies all the unevenness of the substrate; this property is particularly welcome when maintaining coating coverings with an uneven surface. The rubber mixture can also be used, for example, for creating the back layers of waterproofing duplicated films, where the front side is made of a high-quality rubber mixture with high resistance to atmospheric aging, etc. The advantage of the solution is the fact that all the raw materials used in the rubber mixture are of domestic origin, the solution allows the processing of secondary raw materials - rubber crumb or dust.

Example of execution 1

This is a formulation of a mixture recipe for a waterproofing foil for roof waterproofing. The mixture was mixed in a high-pressure kneading machine, a foil 1.5 mm thick was rolled out of the mixture, from which test specimens were cut out and the basic mechanical values were determined.

Parts by weight butadiene-styrene rubber adjusted with oil regenerated rubber zinc oxide stearic acid high-pressure polyethylene with a melt index of 20 rubber crumb mineral oil oxidized asphalt with a softening point of 120 °C kaolin phenyl-beta-naphthylamine

1.5

100

Basic mechanical values:

tensile strength ductility

2.5 MPa elongation elasticity hardness Shore A modulus 100%

1.9 MPa

120 resistance to low temperatures according to NIlSP methodology -36 °C

Structural tear resistance Crescent 26.3 N.mm ^-1

Example of execution 2

This is a formulation of a mixture recipe for a waterproofing membrane suitable for ground waterproofing. The mixture was mixed in a high-pressure kneading machine, accelerators and sulfur were added on a double roller. The mixture was pressed at a temperature of 150 °C/20 into plates 1.5 mm thick, from which test specimens were cut out and the basic mechanical values were determined.

Parts by weight butadiene-styrene rubber regenerated rubber zinc oxide stearic acid high-pressure polyethylene with a melt index of 7 calcium carbonate rubber crumb mineral oil oxidized asphalt with a softening point of 90 °C

N-isopropyl-N'-phenyl-p-phenylenediamine

2-mercapto-benzothiazole tetramethylthiuram disulfide ethyl-phenyl-dithiocarbamate zinc sulfur

Basic mechanical values:

tensile strength elongation elongation elasticity hardness Shore A modulus 100» resistance to low temperatures according to NIlSP methodology structural tear resistance Crescent

Example of execution 3

1.9

120

1.5

1.2

1.5

5.2 MPa 290 « «

»

2.7 MPa

-32 °C 36.8 N.mm

This is a formulation of a mixture recipe for waterproofing foils suitable for repairing damaged roofing and for creating seamless coatings. The mixture was mixed in a high-pressure kneading machine according to the basic recipe, the mixture was divided into three parts, with stearic acid and zinc oxide added to 2 parts of the mixture according to the schedule. Foils 1.5 mm thick were rolled out of the mixtures, test specimens were cut out and the basic mechanical values before aging and after natural aging for 1 year were determined.

Basic recipe

Parts by weight butadiene-styrene rubber 50 regenerated rubber 50 copolymer of ethylene with vinyl acetate with a vinyl acetate content of 12 » by weight 4.0 rubber crumb 20

mineral oil oxidized asphalt softening point 115°C 5 5 soot 30 coumarone gum 2 kaolin 30 silicon dioxide 30 paraffin 0.5 phenyl-beta-naphthylamine 1.2 Mixture e. i No. 2 No. 3 Mass parts stearic acid - 0.8 1.5 zinc oxide - 2 6 Basic mechanical values before aging (determined from samples for mixture no. 1). tensile strength 2.3 MPa ductility 230% extensibility 78% elasticity 12% Shore A hardness 32 Basic mechanical values after natural aging of foil samples after 1 year Mixture No. 1 No. 2 No. 3 tensile strength 1.9 MPa 2.8 MPa 3.1 MPa ductility 180% 210% 240% extensibility 82% 71% 68% elasticity 12 and 14% 14% Shore A hardness 33 35 38

By comparing the values achieved with mixtures No. 2 and No. 3 according to the invention, an increased effect of the solution can be observed compared to the values of the basic mixture No. 1.

Claims (3)

Modified rubber composition based on synthetic rubber for the production of waterproofing foils characterized in that, per 100 wt. parts of styrene-butadiene rubber or a mixture thereof ^one with the regenerated rubber contains 8-40 wt. 20 parts to 150 parts by weight of a high pressure polyethylene or a copolymer of polyethylene with vinyl acetate; parts of rubble or dust, 5 to 25 wt. 60 to 150 wt.% of oxidized asphalt having a softening point above 70 ° C; parts by weight of inorganic fillers or carbon black; parts of mineral oil, 0.8 to 2.5 wt. parts by weight of stearic acid and 2 to 8 wt. parts of zinc oxide. 2. A modified rubber composition according to claim 1, characterized in that, per 100 wt. parts of the rubber component contains 0.4 to 2 wt. % sulfur, 0.6 to 1.5 wt. parts of 2-mercaptobenzthiazole and 1 to 4 wt. parts of fast or ultra-fast vulcanization accelerators. Modified rubber composition according to Claims 1 and 2, characterized in that the vulcanization accelerator can be tetramethylthiuram disulphide, zinc derivatives of dithiocarbamic acid or 0, 0-zinc dithiophosphate.