RU2472821C1 - Fire-resistant rubber mixture - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: fire-resistant rubber mixture contains high-molecular weight methyl vinyl siloxane rubber, finely dispersed silicon dioxide, powder quartz, α,ω-dihydroxydimethyl siloxane, an organic peroxide and melamine cyanurate in ratio of 55-80 pts.wt per 100 pts.wt rubber and, optionally, a pigment. The organic peroxide used can ditertbutyl peroxy isopropyl benzene, 2,5-dimethyl-2,5-dibutylperoxy, or 2,4-dichlorobenzoyl peroxide.

EFFECT: invention reduces the cost of production of the material based on the rubber mixture owing to single-step curing, high fire-resistance with environmentally safe application thereof.

4 cl, 2 tbl

Description

The invention relates to the field of chemistry, in particular to organosilicon rubber mixtures of high fire resistance, and can be used in the electrical industry, in particular, for the manufacture of polymer shells of high-voltage cables and insulators.

A known rubber composition based on butyl rubber containing zinc whitewash and tiuram “D” as a vulcanization accelerator, technical sulfur as a vulcanizing agent, 2-mercapto-benzothiazole as a vulcanization rate regulator, white carbon and technical carbon as a filler, as a plasticizer, stearic acid, chloroparaffin, netoxol, PMS-400 liquid and zinc stearate, antimony trioxide, chlorpapafin and melamine cyanurate as flame retardants, white titanium as a pigment, as ant adhesive - paraffin, with the following ratio of components per 100 parts by weight butyl rubber: vulcanization accelerator - 3.8-4.2; vulcanizing agent - 2.2-2.5; vulcanization rate regulator - 0.8-1.1; filler - 33.0-34.1; plasticizer - 18.8-22.9; flame retardants - 55-59; pigment - 9-10 and release agent - 1.9-2.1. Fire retardants include, parts by weight: antimony trioxide - 4-6; chloroparaffin - 7.0-7.5 and melamine cyanurate - 44-46, which give a synergistic effect of increasing fire resistance (Patent RU No. 2388608 C1. Composite laminated rubber-fabric protective material. - IPC B32V 25/10, C08K 7/02. - 10.05. 2010). The vulcanizate of this composition contains hydrocarbon rubber for general use, HC groups. A disadvantage of the known vulcanizate composition is the presence of chloroparaffin in it, which releases chlorine into the environment, harmful and dangerous to human health and all living things, on the one hand, and on the other hand, such a vulcanizate cannot be used in the cable industry, because with it, enhanced oxidation of metal conductors occurs. Currently, the rubber industry refuses to use organohalogen flame retardants in rubber compositions.

Known rubber mixture based on high molecular weight methyl vinyl siloxane rubber, taken in an amount of 70-80 parts by weight, additionally, as a polymer base contains low molecular weight methyl vinyl siloxane rubber in an amount of 20-30 parts by weight, includes pulverized silica 170-200 parts by weight, aerosil 40-50 parts by weight, anti-structuring agent - α, ω-dihydroxydimethylsiloxane 8-10 parts by weight, organic peroxide 1.5-2.0 parts by weight (Patent RU No. 2224774 C1. Rubber compound based on high molecular weight methyl vinyl siloxane rubber. - IPC ⁷ C08L 19/00, C08L 83/04, C08K 13/02, C08K 3/36, C08K 5/14. - 02.27.2004). This rubber composition contains silicone rubber of the SiO group. The main disadvantage of the known rubber compound is its low fire resistance.

The closest analogue of the claimed invention is a composite material based on a rubber mixture containing, as a polymer matrix, a mixture of high molecular weight polymethylvinylsiloxane and low molecular weight polymethylvinylsiloxane rubber, in combination with a possible stearic acid, flame retardant, dehydrating agent, aerosil, quartz, anti-structural agent dihydroxydimethylsiloxane, organic peroxide, water repellent - organosilicon liquid. As a fire retardant filler, the composite material may contain, for example, hydrated hydroxides of calcium, magnesium, aluminum, calcium carbonate, magnesium carbonate. This rubber mixture contains silicon rubber of the SiO group and is environmentally friendly (Patent RU No. 2285306 C2. Fire-resistant self-extinguishing electric cable or wire. - IPC ⁷ Н01В 13/24, C08J 5/00. - 10.10.2006). This invention is taken as a prototype.

The main disadvantage of the known composite material based on a rubber mixture is its two-stage vulcanization and insufficient fire resistance.

The main task to be solved by the claimed invention is directed is the creation of a rubber compound by one-stage vulcanization with increased fire resistance and is safe for the environment.

The technical result achieved by the implementation of the claimed invention is to reduce the cost due to one-stage vulcanization and increase the resistance to ignition with environmental safety of its use.

The specified technical result is achieved by the fact that the known fire-resistant rubber mixture based on high molecular weight methyl vinyl siloxane rubber contains finely divided silica, pulverized silica, α, β-dihydroxy dimethyl siloxane, organic peroxide, melamine cyanurate, the latter in a ratio of 55-80 wt.h. per 100 parts by weight high molecular weight methyl vinyl siloxane rubber, and, if necessary, a pigment;

as an organic peroxide contains:

ditretbutylperoxyisopropylbenzene or

2,5-dimethyl-2,5-dibutylperoxy-hexane or

2,4-dichlorobenzoyl.

The analysis of the prior art by the applicant has made it possible to establish that there are no analogs characterized by sets of features identical to all the features of the declared flame retardant rubber mixture based on high molecular weight methylvinylsiloxane rubber. Therefore, the claimed technical solution meets the condition of patentability "novelty."

The search results for known solutions in the art in order to identify features that match the distinctive features of the prototype of the features of the claimed technical solution have shown that they do not follow explicitly from the prior art. From the prior art determined by the applicant, the influence of the transformations provided for by the essential features of the claimed technical solution on the achievement of the specified technical result is not revealed. Therefore, the claimed technical solution meets the condition of patentability "inventive step".

The quality of the ingredients used for the preparation of fire-resistant rubber mixture of one-stage vulcanization meets the requirements laid down in the following regulatory and technical documentation:

high molecular weight methyl vinyl siloxane rubber, SKTV-1, - TU 38.103675-89;

fine silica (Aerosil grade A-300, GOST 14922-77);

pulverized quartz, GOST 9077-82, or the brand "Sicron SF 4000";

α, ω-dihydroxydimethylsiloxane (product ND-8, TU 2229-044-05766764-01);

ditretbutylperoxyisopropylbenzene peroxide (Peroximon F-40, China);

2,5-dimethyl-2,5-tert-butylperoxyhexane peroxide (MBPGA, China);

2,4-Dichlorobenzoyl peroxide (2,4-DCB Peroxide Paste, Poland);

melamine cyanurate EXFLAM MCA (China);

pigment red iron oxide grade K, TU U 6-05766356.034-96.

A fire-resistant rubber mixture of one-stage vulcanization with a specific formulation of the components indicated in Table 1 was prepared in a PC-250 mixer by sequential mixing, first high molecular weight methyl vinyl siloxane rubber (SKTV-1) with fine silica (Aerosil A-300) and α, ω- dihydroxydimethylsiloxane (product ND-8) at room temperature of 20-30 ° C to a homogeneous mass, then the mixer was heated to a temperature exceeding room temperature, into which Sicron SF pulverized quartz was successively introduced 4000 and melamine cyanurate EXFLAM МСА as a flame retardant, then the whole mass was mixed until a uniform structure of the mixture was formed, and then cooled to room temperature. Ditretbutylperoxyisopropylbenzene peroxide (Peroximon F-40) or 2,5-dimethyl-2,5-dibutylperoxyhexane peroxide (MBPGA) or 2,4-dichlorobenzoyl peroxide (2,4-DCB Peroxide Paste) as an organic peroxide, and also if necessary, a pigment, for example, red iron oxide grade K, was added to the rollers to give the rubber the desired color.

Table 1 Name of components The number of starting components, g / wt.h. Example 1 Example 2 Example 3 Rubber SKTV-1 one hundred one hundred one hundred Aerosil A-200 47 52 55 Sicron SF 4000 40 25 10 Product ND-8 10 10 8 Melamine cyanurate EXFLAM MCA 55 65 80 2,5-dimethyl-2,5-dibutylperoxyhexane peroxide MBPGA - - 3,5 Peroximon F-40 3.3 - - 2,4-DHB Peroxide Paste - 2,5 - K grade red iron oxide pigment - 2.0 2.0

Table 2 shows the indicators of the electrophysical properties of the obtained vulcanizate fire-resistant rubber mixture of one-stage vulcanization.

table 2 Indicators Values Rolling ability, min, no more 5 Density, g / cm ³ , no more 1.45 Conditional tensile strength, MPa, not less 4.0 Elongation at break,%, not less than 300 Shore A hardness, conv. units within 58-70 Volumetric electrical resistivity, Ohm · cm, not less 1 · 10 ¹⁴ Dielectric loss tangent, not more than 0.04 Dielectric strength at a frequency of 50 Hz, kV / mm, not less eighteen Dielectric constant, no more 5.0 Flammability Class FV (PV) 0 Erosion tracking Class 1A4.5

The properties of the vulcanizate flame retardant rubber mixture were determined according to the methods of the following standards.

GOST 269-66. Rubber. General requirements for physical and mechanical tests.

GOST 270-75. Rubber. Method for determination of tensile strength properties.

GOST 263-75. Rubber. Shore A Hardness Test Method

GOST 267-73. Rubber. Density determination method.

GOST 6433.2-71. Solid electrical insulating materials. Methods for determining electrical resistance at constant voltage.

GOST 6433.3-71. Solid electrical insulating materials. Methods for determining the electric strength at alternating (frequency 50 Hz) and constant voltage.

GOST 6433.4-71. Solid electrical insulating materials. Methods for determining the tangent of the dielectric loss angle and permittivity at a frequency of 50 Hz.

GOST 27474-87. Electrical insulating materials. Test methods for resistance to the formation of conductive bridges and erosion in harsh environmental conditions.

GOST 28779-90 (IEC 707-81). Solid electrical insulating materials. Methods for determining flammability under the influence of an ignition source.

The introduction to the formulation of the rubber mixture of one melamine cyanurate as a flame retardant in an amount of 55-80 parts by weight per 100 parts by weight high molecular weight methyl vinyl siloxane rubber can significantly reduce the cost of finished products, increase resistance to ignition, elasticity and have good electrical insulation performance without harmful effects on the environment.

Claims (4)

1. Flame retardant rubber mixture based on high molecular weight methyl vinyl siloxane rubber containing fine silica, pulverized silica, α, ω-dihydroxy dimethyl siloxane organic peroxide, melamine cyanurate, the latter in a ratio of 55-80 parts by weight. per 100 parts by weight high molecular weight methyl vinyl siloxane rubber, and optionally pigment. 2. The rubber mixture according to claim 1, characterized in that the organic peroxide contains ditretbutylperoxyisopropylbenzene. 3. The rubber mixture according to claim 1, characterized in that the organic peroxide contains 2,5-dimethyl-2,5-dibutylperoxyhexane. 4. The rubber composition according to claim 1, characterized in that the organic peroxide contains 2,4-dichlorobenzoyl peroxide.