RU2231532C1 - Cold-solidification organosilicon composition - Google Patents

Abstract

FIELD: organosilicon materials.

SUBSTANCE: invention provides organosilicon composition comprising, wt parts: linear-staircase block copolymer of following general formula:

wherein x = 4-7, y =205-250, 100; inorganic filler: silicon oxides and/or aluminosilicate fibers, 1-26.5; structurization agent: tetraethoxysilane or its incomplete hydrolysis products, 0.9; solidification catalyst: tin dibutyl dilaurate, γ-aminopropylethoxysilane, or vinyl-tris(acetoximoxy)silane, 1-20; and additionally thermostabilization agent: iron phosphides, nickel phosphides, iron oxide, copper oxide, cerium oxide, or mixture thereof deposited, as active phase, on metals or metal oxides selected from aluminum, iron, and titanium groups, 3-10.6. Composition is intended for heat-resistant elastic materials operated at 300-350^оС and, for a short time, at 400^оС.

EFFECT: improved insulation, strength, and adhesion properties.

3 tbl, 2 ex

Description

The invention relates to the field of organosilicon compositions, cured in the cold, to obtain heat-resistant elastic materials. Materials are widely used in various industries and equipment as coatings, universal adhesives, gaskets, casting compounds, including those working in extreme conditions of high and / or low temperatures.

Known two-component silicone composition of cold curing (ed. Certificate. USSR No. 731780, 1983, IPC C 08 L 83/04). It consists of low molecular weight organosilicon rubber with terminal functional groups as a polymer base (100 parts by weight), silicon oxides and titanate as fillers (8-12 parts by weight), and tin octoate, a curing catalyst (0.8-1, 2 parts by weight) It is used as a casting compound cured at ambient temperature. The material is efficient when heated to 180 ° C, but has low adhesive strength.

Also known is a composition based on organosilicon rubber (ed. Certificate. USSR 1697406, 1996, IPC C 08 L 83/04), vulcanized at room temperature and forming sealing materials for use in aircraft construction.

Materials retain their working properties in a confined space for 100 hours at sufficiently high temperatures. The composition includes, parts by weight: silicone rubber (base) in an amount of 100, filler 20-120, polymethylhydrosilazane 0.2-10 and tin diethyl dicaprylate 0.3-10. Rubber has MM = 20 × 10 ³ -200 × 10 ³ and contains units (CH ₃ RSiО), where R is CH ₃ , CH ₂ CH ₂ CF ₃ .

Silicon or titanium dioxide is used as filler. The material has a tensile strength of 23-30 kg / cm ² and elongation, respectively, 180-80% (before and after aging). The resulting material with the preservation of elasticity can only work up to 250 ° C.

It is also protected by the USSR copyright certificate No. 1694604, 1991, IPC C 08 L 83/04, C 08 K 9/06, a polymer composition based on low molecular weight siloxane rubber, which can be used to seal products in machine and instrument engineering. The composition allows to increase the tensile strength of materials obtained after curing. Organosilicon waste was added to its composition, crushed to a particle size of 3 cm and treated with a mixture of tetraethoxysilane, potassium hydroxide and water, in addition, the composition also contains a thermostabilizing additive - iron oxide pigment - in an amount of 1 to 8 parts by weight. and polycuprofosphorsiloxane in an amount of 0.3 parts by weight The temperature and operational characteristics of the materials are not given.

The closest analogue in technical essence and the achieved effect is a cold-cured silicone composition protected by RF patent No. 2105778, 1998, IPC C 08 L 83/04 and C 08 K 13/02, for sealing electronic, radio and electrical devices.

The composition contains low molecular weight organosiloxane rubber with terminal hydroxyl groups (base or binder), 100 parts by weight, inorganic filler - Aerosil A3 00 or titanium dioxide, shale ash in an amount of 1-100 parts by weight, structuring agent - tetraethoxysilane, ethyl silicate 40 or 32. The binder is, in particular, a linear ladder block copolymer of the brand Lestosil H of the formula

As a catalyst, specially treated DEGA or DMGA in an amount of 1.5-8 parts by weight were used. The composition cures within 24 hours at room temperature.

According to the physicomechanical characteristics, vulcanizates before aging have low strength characteristics (σ = 14-17 kg / cm ² , L = 150%, after aging in vacuum at 300 ° С σ = 5-6 kg / cm ² , L = 80-120%) even when using block copolymer (B). In the present invention, all compositions were used as adhesives for rubbers. The results of tensile testing of materials showed the destruction of rubbers at a temperature of 300 ° C. In other words, the resulting materials do not withstand high temperatures, which is a serious drawback of the proposed composition.

The authors of the alleged invention faced the task of developing a composition for the production of heat-resistant elastic materials, operable at temperatures of 300-350 ° C, for a short time at 400 ° C, with high electrical insulating, strength and adhesive properties.

As a result of scientific and experimental studies, we developed an organosilicon composition, which includes a linear-stair block copolymer of the general formula

inorganic filler - silicon or aluminum oxides, and / or aluminosilicate fibers 1-26.5 parts by weight,

a structuring agent is tetraethoxysilane or products of its incomplete hydrolysis 0-9 parts by weight,

the curing catalyst is tin dibutyl dilaurate, γ-aminopropyltriethoxysilane or vinyltris (acetoxyxyoxy) silane 1-20 parts by weight

and additionally introduced a heat-stabilizing agent - phosphides of iron, nickel, iron, copper, cerium oxides or a mixture thereof, applied as an active phase to metals or metal oxides selected from the group of aluminum, iron and titanium, 3-10.6 wt.h.

The composition is prepared by mixing the components in a paddle mixer until a homogeneous mixture is obtained, after which a structuring agent and catalyst are added to it in the required amount. The mixture is cured at ambient temperature until an elastic rubber-like material is formed within 1-3 days. Thermostabilizing agents used in the compositions are shown in table 1.

Example 1

(No. 3, table 2). Into the mixing device is introduced, parts by weight:

Block copolymer 100

Silica 3

Aluminosilicate fibers 5

Thermostabilizing agent No. 2 7.5

The mass is stirred for 5 minutes, after which it is added, wt.h .:

γ-aminopropyltriethoxysilane 1

Ethyl silicate 40 5

The resulting mixture was stirred and cured in the cold for 2 days at ambient temperature.

Physico-mechanical properties of the vulcanizate based on this composition are shown in table 2, No. 3.

Example 2 (No. 8, table 2). In the mixing device is introduced, wt.h.

Block copolymer 100

Alumina 20

Silica 3

Thermostabilizing agent No. 7 7.5

The resulting mass is stirred for 5 minutes, then a vinyltris (acetoxyximoxy) silane curing catalyst (18 parts by weight) is added to it.

The resulting mixture was stirred and cured in the cold at ambient temperature for 3 days.

Physico-mechanical properties of the vulcanizate based on this composition are presented in table 2, No. 8.

Other examples of the composition of the composition and physico-mechanical properties of the vulcanizates obtained on their basis are also given in table 2. The synthesized compositions have high dielectric properties. Their characteristics are given in table 3.

The technical solution we developed meets the criteria of patentability and, in our opinion, can be examined by an examination for the issue of a patent of the Russian Federation.

Claims (1)

An organosilicon cold curing composition based on a linear ladder block copolymer for producing heat-resistant elastic materials, including an inorganic filler and a curing catalyst, characterized in that it contains a linear ladder block copolymer of the formula

where x = 4-7; y = 205-250, inorganic filler — silicon or aluminum oxides and / or aluminosilicate fibers, a curing catalyst — tin dibutyl dilaurate or its derivatives, gamma-aminopropyltriethoxysilane or vinyltris (acetoxyxyoxy) silane and additionally contains a thermostabilizing agent — iron, nickel, iron, copper, cerium phosphides or their a mixture deposited on metals or metal oxides selected from the group aluminum, iron and titanium, and, if necessary, a structuring agent - tetraethoxysilane or products of its incomplete hydrolysis, followed by the ratio of components, parts by weight: Organosilicon base 100 Inorganic filler 1 - 26.5 Structuring agent 0 - 9 Curing catalyst 1 to 20 Thermostabilizing agent 3 - 10.6