Low-viscosity siloxane composition

FIELD: chemistry.

SUBSTANCE: invention concerns low-viscosity siloxane compositions which can be solidified at room temperature and form elastomer materials applicable as dielectrics and insulators. Invention claims low-viscosity siloxane composition including, weight parts: polyorganosiloxanediol - polydimethylsiloxanediol or polydimethyl(methylphenyl) siloxanediol or their mix at the molar weight ratio of (2÷1):1, 15÷100 thousand - 100, partial tetraethoxysilane hydrolysis product - 4.0÷7.2, amonisilane selected out of group including γ-aminopropyltriethoxysilane or its mix with (3-aminoisopropyltriethoxysilane or diethylamonipropyltetraethoxysilane - 0.5÷1.0. Composition can include fine-dispersed filler quartz, silicon dioxide or dolomite powder, iron, titanium, aluminium, chrome or zinc oxides or their mixes, boron or aluminium nitrides, or mixes of carbon black with metal oxides, oligodimethylsiloxane.

EFFECT: low-viscosity siloxane composition for obtainment of elastic dielectric material without corrosion effect on non-ferrous metals, with high dielectric properties, enhanced substrate adhesion and reduced toxicity, at room temperature.

8 cl, 2 tbl, 2 ex

 

The invention relates to the field of low viscosity siloxane compositions capable of curing at room temperature with the formation of elastomeric materials that can be used as dielectrics and insulators used in sealants, compounds, coatings in mechanical engineering, including instrumentation and electronics.

Known compositions based on liquid siloxane rubbers with terminal silanol groups obtained by mixing rubber, cross-linking agents containing hydrolyzable alkoxy - or alloctype, and catalysts cold vulcanization, which usually use ORGANOTIN (patent of Ukraine # 54005, AB. mon. The USSR №496293, 1685962) or technologicheskie connection (patent JP 11228700).

The disadvantages of the known compositions are increased corrosivity and toxicity due to the use of tin - and technologicheskij connections.

The closest in composition similar to that adopted for the prototype, is a low viscosity siloxane composition comprising, in parts by weight:

liquid silicon rubber with integral
silanol groups100
ethyl silicate 30-80
ORGANOTIN catalyst3,0-12,0
alkyl(aryl)acetoxysilane0.5 to 1.5

(patent RF №2052475).

The disadvantages of the composition of the prototype are: high corrosivity due to the content of a significant number of acidic components, as in the vulcanization process is the acid that causes the corrosion of metals, particularly non-ferrous (copper, silver, their alloys), which makes it unsuitable for use by the instrumentation, the ability to vulcanizates only in a thin layer, a low dielectric properties. Additionally, the ORGANOTIN catalysts are highly toxic substances.

The technical object of the present invention is to develop a low viscosity siloxane composition to obtain at room temperature elastic material that does not cause corrosion of non-ferrous metals having a high dielectric properties, improved adhesion to substrates and reduced toxicity.

To solve this problem is proposed low viscosity siloxane composition comprising a liquid siloxane rubber having terminal silanol groups, the product of partial hydrolysis of tetraethoxysilane and the catalyst, featuring the jaś fact, as the liquid siloxane rubber having terminal silanol groups it contains polyorganosiloxane Malm 15-100 thousand, and as a catalyst - aminosilane in the following ratio of components, parts by weight:

polyorganosiloxanes Malm 15-100 thousand100
the product of partial hydrolysis of tetraethoxysilaneof 4.0 to 7.2
aminosilane0,5-1,0

As polyorganosiloxane composition contains polydimethylsiloxane or polydimethyl(were)ilocandia or their mixture in the ratio from (2-1):1.

As aminosilane composition contains aminosilane selected from the group comprising γ-aminopropyltriethoxysilane or its mixture with β-aminoethoxyethanol or diethylaminopropylamine.

To improve mechanical characteristics of the composition may further contain fine aggregate in the amount of 25.0-263,0 parts by weight of the filler composition may contain quartz, silicon dioxide or dolomite flour, oxides of iron, titanium, aluminum, chromium or zinc, or mixtures thereof, boron nitride or aluminum or a mixture of carbon black with metal oxides the century

For the purpose of regulating the viscosity of the composition may further contain oligodimetilsiloksana in an amount of 10-30 parts by weight of

The correct qualitative and quantitative selection of the catalyst and crosslinking agent in the composition provides reception after curing at room temperature elastomeric material is a dielectric with a minimum allocation of non-corrosive by-products (water, ethyl alcohol), which explains the absence of corrosive effect of the composition on non-ferrous metals.

The chemical nature of the used siloxane rubber, proper selection of fillers and no side products of vulcanization with electrolytic properties provides a high level of dielectric properties of vulcanizates of the claimed composition.

The set of active groups of the components of the composition allows to obtain elastomeric material with high adhesion to various substrates.

As polyorganosiloxane in the present invention can be used in a variety polyorganosiloxanes Malm 15-100 thousand, but the best technical result is achieved when using polydimethylsiloxane brands SCTN "G", SCTN "B", SCTN "A" (GOST 13835-73), polydimethyl(were)ilocandia brand SCTP "B" with the content 4-50 mol % methylvinylsiloxane frame link guides the EV (TU 38.108129-77), as well as their mixtures in the ratio from (2-1):1.

As a cross-linking agent was used, the product of partial hydrolysis of tetraethoxysilane - ethyl silicate-40 with the content of SiO238-43% (GOST 26371-81).

As aminosilane it is most preferable to use γ-aminopropyltriethoxysilane or its mixture with β-aminoethoxyethanol (TU 6-02-724-73) or diethylaminopropylamine (TU 6-02-586-86).

As viscosity regulator can be used oligomerisation with a kinematic viscosity at 20°C from 5 to 150 mm2/sec, preferably with a viscosity of 10-150 mm2/s PMS-10, PMS-50, PMS-150 (GOST 23175-78).

As the fine inorganic fillers used silicon dioxide (TU 2168-016-002048-72-2003), quartz, oxides of metals such as iron (GOST 4173-77), zinc (GOST 202-84), titanium (TU 6-10-1252-86), aluminum, chromium (GOST 2.912-79), or a mixture thereof, boron nitride (TU 2-036-707-77), aluminum or a mixture of carbon black, for example, grades P-803 (GOST 7885-86) with metal oxides.

Examples of implementation

Example 1

To 100 parts by weight of polydimethylsiloxane with a molecular mass of 15 thousand (SCTN "A") was added to 4.5 parts by weight of ethyl silicate - 40, and 0.5 parts by weight of γ-aminopropyltriethoxysilane. The composition was stirred for 5 minutes and used to fill the prepared products. Control sample to study the properties to the pound formed in the shape of a plate thickness of ~2 mm The tests were carried out after three days of exposure of samples at room temperature.

Example 2

To to 66.7 parts by weight of polydimethylsiloxane with a molecular mass of 50 thousand (SCTN G) was added to 33.3 parts by weight of polydimethyl(were)ilocandia with a molecular mass of 20 thousand (SCTP "B"), was introduced 200 parts by weight of zinc oxide and 6 parts by weight of iron oxide, was stirred for 2 hours at clearesult to obtain a homogeneous paste. In the resulting paste was introduced to 6.5 parts by weight of ethyl silicate-40, and 0.5 parts by weight of γ-aminopropyltriethoxysilane and 0.2 parts by weight of β-aminoisobutyrate. The mixture was stirred for 5 minutes and used to fill the prepared product.

The compositions of examples 3-9 are prepared in a similar manner.

The invention is not limited to these examples.

Table 1 shows the compositions of the claimed composition, in table 2 - comparative properties.

Presented in table 2 data shows that the proposed low viscosity siloxane composition has significant advantages such as technological indicators - contains components not lower than grade 4 toxicity instead of 1-2 class prototype has viability (in layers not less than 3 cm) from 40 minutes to 6 hours instead of 5-10 days in prototype and operational properties - has its own adhesion to metallic substrates (this has a cohesive characteristic is cter separation when instead of peeling the adhesive from the prototype), does not cause corrosion of ferrous metals in contrast to the prototype and has a high dielectric characteristics (ρv, ρs- higher by several orders of magnitude) compared to the prototype.

The use of the invention allows a reliable sealing and electrical insulation products materials, elastic and dielectric properties during long-term operation in the temperature range from minus 120°C to 300°C, while the composition of the prototype lose their elasticity during prolonged storage, even at room temperature due to the high content structuring agents.

High technological properties, low toxicity, high dielectric characteristics, its own adhesion to various metals, performance in a wide temperature range allow you to apply the present invention in various fields of engineering with a considerable reduction of labor intensity, energy intensity of the production process, and to ensure the environmental safety of the process seal.

1. Low viscosity siloxane composition comprising a liquid siloxane rubber having terminal silanol groups, the product of partial hydrolysis of tetraethoxysilane and the catalyst, trichomania fact, as the liquid siloxane rubber having terminal silanol groups it contains polyorganosiloxane with molm 15÷100 thousand, and as a catalyst - aminosilane in the following ratio of components, parts by weight:

polyorganosiloxanes, Malm 15÷100 thousand100
the product of partial hydrolysis of tetraethoxysilane4,0÷7,2
aminosilane0,5÷1,0

2. Low viscosity siloxane composition according to claim 1, characterized in that as polyorganosiloxane it contains polydimethylsiloxane, or polydimethyl(were)ilocandia, or their mixture in the ratio (2÷1):1.

3. Low viscosity siloxane composition according to claim 1, characterized in that as aminosilane it contains aminosilane selected from the group comprising γ-aminopropyltriethoxysilane or its mixture with β-aminoethoxyethanol or diethylaminopropylamine.

4. Low viscosity siloxane composition according to claim 1, characterized in that it further contains a filler in the amount of 25.0÷263,0 parts by weight of

5. Low viscosity siloxane composition according to claim 4, characterized in that the filler it contains quartz, dioxi the silicon or dolomite flour.

6. Low viscosity siloxane composition according to claim 4, characterized in that the filler it contains oxides of iron, titanium, aluminum, chromium or zinc, or mixtures thereof, or mixtures thereof with technical carbon.

7. Low viscosity siloxane composition according to claim 4, characterized in that the filler it contains boron nitride or aluminum.

8. Low viscosity siloxane composition according to claim 1, characterized in that it further comprises the oligodimetilsiloksana in the amount of 10.0÷30,0 parts by weight of



 

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