RU2263130C1 - Heat-resistant foam-sealing agent - Google Patents

Abstract

FIELD: foam-sealing agents.

SUBSTANCE: invention describes a heat-resistant foam-sealing agent comprising polyorganosiloxane rubber, zinc oxide, oligohydride siloxane, amino-compound and vulcanization catalyst. Heat-resistant foam-sealing agent comprises polydimethylmethylphenylsiloxanediol as polyorganosiloxane rubber, oligomethylhydride siloxane as oligohydride siloxane, aminosilane as amino-compound and polyorganoelementosilazane resin as a catalyst in the following ratio of components, mas. p. p.: polydimethylmethylphenylsiloxanediol, 100; zinc oxide, 40-80; oligomethylhydride siloxane, 2.5-4.8; aminosilane, 0.1-0.3; polyorganoelementosilazane resin, 1.5-3.5. Invention provides the development of technological foam-sealing agent showing sufficiently long working life for pouring article to be sealed (30 min, not less), without toxicity, possessing internal adhesion to different backings, retaining elasticity at temperatures from -100°C to +300°C and vulcanizing at room temperature.

EFFECT: improved and valuable properties of agent.

5 cl, 2 tbl, 5 ex

Description

The invention relates to the field of expandable organosilicon compositions that can be used for electrical insulation and protection of various devices and assemblies, for example, electrical connectors in aircraft, instrumentation and other industries.

Foaming compositions based on organosilicon rubbers are known in which foaming occurs due to the evolution of gaseous products during the reaction between the components of the compositions: for example, carbon dioxide (RF patent No. 2115676) or hydrogen when using organohydride siloxanes containing at least two groups - Si-H in molecule (US patent No. 5238967, 5356940). Organic peroxides (ed. Certificate of the USSR No. 726139), platinum or tin compounds (US patents No. 5238967, 5356940) are used as catalysts in the compositions.

A disadvantage of the known solutions is the low manufacturability of the compositions — after mixing the components, the viscosity quickly increases, the pot life is 2-10 minutes, in the case of using platinum and peroxide catalysts, vulcanization occurs only at elevated temperatures (from 80 ° C to 220 ° C).

The closest analogue adopted for the prototype is heat-resistant foam rubber, including, parts by weight: SKTN polydimethylsiloxane rubber with a molecular weight of 40-80 thousand - 100, filler - zinc oxide and titanium oxide - 20-40, organosilicon hydride siloxane liquid GKZH- 94 - 20, polyethylene polyamine - 1 and a vulcanization catalyst - tin diethyl dicaprylate - 1-4 (ed. Certificate of the USSR No. 309029).

The disadvantages of the prototype are the low viability of the composition (5-10 minutes), the high toxicity of the catalyst (tin diethyl dicaprylate belongs to hazard class 1), as well as the lack of adhesion of foam rubber to the substrates and its heat resistance limited to 250 ° C. Foam rubber also becomes brittle in the temperature range (-55) - (- 60) ° С.

The technical task of the invention is the development of technological foam sealant having a sufficiently long viability for pouring sealed products (at least 30 minutes), non-toxic, with its own adhesion to various substrates, preserving elasticity at temperatures from -100 to + 300 ° C and vulcanizing at room temperature .

To solve the stated technical problem, a heat-resistant foam sealant is proposed, including polyorganosiloxane rubber, zinc oxide, oligohydridosiloxane, an amino compound and a vulcanization catalyst, characterized in that it contains polydimethylmethylphenylsiloxane diamino, and as an oliganosilane, oliganosilane the catalyst is a polyorganoelementosilazane resin in the following ratio of components, parts by weight:

polydimethylmethylphenylsiloxanediol 100 zinc oxide 40-80 oligomethyl hydride siloxane 2.5-4.8 aminosilane 0.1-0.3 polyorganoelementosilazane resin 1,5-3,5

As an aminosilane, the foam sealant contains an aminosilane selected from the group consisting of: γ-aminopropyltriethoxysilane or a mixture thereof with β-aminoisopropyltriethoxysilane, diethylaminomethyltriethoxysilane or 1-aminohexamethylene-6-aminomethylenetriethoxysilane.

In order to control the viscosity, the foam sealant may additionally contain polydimethylsiloxanediol in an amount of 1.0-20.0 parts by weight, as well as oligoalkylsiloxane in an amount of 1.0-4.0 parts by weight.

As the oligoalkylsiloxane, the foam sealant may contain oligomethylsiloxane or oligoethylsiloxane.

The correct selection of the amino compounds with the activity of amino groups that is optimal for the process of obtaining a foam sealant explains the sufficiently long induction period of the foaming reaction, which ensures the necessary viability of the compositions, and the products released during the reaction are autocatalysts of the process, which leads to the formation of foamed non-sticky vulcanizates in a few hours. The combination of active foam sealant groups allows one to obtain a material with self-adhesion to various substrates.

In the present invention was used polydimethylmethylphenylsiloxane diol according to TU 38 108129-77.

Various representatives of this class of compounds can be used as aminosilane, but it is most preferable to use γ-amino-propyltriethoxysilane or its mixture with β-aminoisopropyltriethoxysilane (TU 6-02-724-73), diethylaminomethyltriethoxysilane (TU 6-02-573-77) or 1-aminohexamethylene-6-aminomethylenetriethoxysilane (TU 6-02-586-86). As oligohydridesiloxane in the present invention, it is most preferable to use oligomethylhydridesiloxane (TU 2229-013-40245042-00). As a polyorganoelementosilazane resin, it is most preferable to use resins according to TU 6-02-1003-75 with a mass content of nitrogen of 9-25%, silicon - 15-28% and titanium - 0.3-5.0%. It is advisable to use oligoalkylsiloxanes as viscosity regulators, which are preferable to use oligoethylsiloxane (GOST 25149-82) or oligomethylsiloxane (TU 2416-54), as well as polydimethylsiloxane diol (GOST 13835-73).

Examples of compositions of heat-resistant foam sealant are shown in table 1, the comparative properties of the proposed sealant and prototype in table 2.

Examples of implementation

Example 1

100 parts by weight polydimethylmethylphenylsiloxanediol is mixed with 80 parts by weight of zinc oxide, 4.8 wt.h. oligomethylhydridesiloxane, 0.3 wt.h. γ-aminopropyl-triethoxysilane and 2.0 parts by weight polyelementosilazane resin. The mixture is stirred for 5 minutes and then used to fill the prepared (purified and degreased with solvent) products and a control sample to study the properties of the foam sealant (density, heat resistance and frost resistance of the vulcanizate). The tests are carried out after three days of exposure of the samples at normal temperature.

The foam sealant of Examples 2-5 is prepared in a similar manner.

The invention is not limited to these examples.

From the data presented in table 2, it can be seen that the proposed composition of heat-resistant foam sealant has significant advantages both in technological parameters - does not contain toxic components, has a long viability of 30 to 90 minutes instead of 5-10 minutes for the prototype, and in operational properties - it has its own adhesion to metals and plastics, retains elasticity in a wide temperature range from -100 ° C to + 300 ° C in comparison with the prototype, which retains elasticity in a temperature range from -60 ° C to + 250 ° C. The application of the present invention allows reliable sealing and electrical insulation of various instrumentation devices, including products that are operated both at high (up to + 300 ° C) and at low temperatures (up to -100 ° C). Foam sealant can also be used as a vibration and sound insulating material in a wide temperature range. High technological properties, non-toxicity, ease of use, which does not require special fastening of the sealant to substrates and the use of high temperatures for vulcanization, significantly reduce the complexity and energy consumption of the process of sealing devices and ensure its environmental safety.

Table 1 Name of components The composition according to examples, parts by weight Prototype 1 2 3 4 5 Polydimethylmethylphenylsiloxanediol 100 100 100 100 100 - Zinc oxide 80 60 40 fifty 60 40 Oligomethyl Hydride Siloxane 4.8 3.0 2,5 3.2 3,5 - γ-aminopropyltriethoxysilane 0.3 - - 0.2 - - Diethylaminomethyltriethoxysilane - - 0.3 - - - Mixture of γ-aminopropyltriethoxysilane with β-aminoisopropyltriethoxysilane - 0.1 - - - - 1-aminohexamethylene-6-aminomethylene triethoxysilane - - - - 0.16 - Polyorganoelementosilazane Resin 2.0 2,3 3,5 1,5 1.8 - Polydimethylsiloxanediol - - twenty 12 1,0 - Oligoethylsiloxane - 1,0 - 4.0 - - Oligomethylsiloxane - - 4.0 - 2.0 - Polydimethylsiloxane rubber - - - - - 100 Silicone hydride-siloxane liquid GKZH-94 - - - - - twenty Polyethylene polyamine - - - - - 1,0 Tin diethyl dicaprylate - - - - - 4.0

table 2 Name of properties Examples of the invention Prototype 1 2 3 4 5 Viability, min 90 fifty thirty 40 60 10 Toxicity non toxic non toxic non toxic non toxic non toxic Hazard class 1 Density, g / cm ³ 0.7 0.65 0.48 0.50 0.64 0.5 Elasticity after holding for 50 hours at 300 ° C retained elasticity retained elasticity retained elasticity retained elasticity retained elasticity fragile Elasticity after holding for 1 h at -70 ° C retained elasticity retained elasticity retained elasticity retained elasticity retained elasticity solid glassy Adhesion to aluminum alloy D-16 good good good good good is absent Adhesion to fiberglass EDT-10P good good good good good is absent Vulcanization temperature room room room room room room

Claims (5)

1. Heat-resistant foam sealant including polyorganosiloxane rubber, zinc oxide, oligohydridesiloxane, amine compound and vulcanization catalyst, characterized in that it contains polydimethylmethylphenylsiloxane-oligosiloxane-oligosiloxane-oligosiloxane-oligosiloxane-oligosiloxane-oligosiloxane-oligosilane-oligosilane-oligosilane in the following ratio of components, parts by weight: Polydimethylmethylphenylsiloxanediol 100 Zinc oxide 40-80 Oligomethyl Hydride Siloxane 2.5-4.8 Aminosilane 0.1-0.3 Polyorganoelementosilazane Resin 1,5-3,5 2. The heat-resistant foam sealant according to claim 1, characterized in that it contains an amino silane selected from the group consisting of γ-aminopropyltriethoxysilane or its mixture with β-aminoisopropyltriethoxysilane, diethylaminomethyltriethoxysilane or 1-aminohexamethylene-6-aminomethine. 3. The heat-resistant foam sealant according to claim 1, characterized in that it further comprises polydimethylsiloxanediol in an amount of 1-20 wt.h. 4. The heat-resistant foam sealant according to claim 1, characterized in that it further comprises oligoalkylsiloxane in an amount of 1-4 parts by weight 5. The heat-resistant foam sealant according to claim 4, characterized in that it contains oligomethylsiloxane or oligoethylsiloxane as oligoalkylsiloxane.