RU2522614C2 - Method of improving adhesion to metals of silicon composite materials, obtained by reaction of polyaddition - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to silicon composite materials. A method of improving adhesion to metals of silicon composite materials includes obtaining by a polyaddition reaction of a composite material, containing polydimethylsiloxane with terminal vinyl groups of the general formula (CH₂=CH)(CH₃)₂Si-[O-Si(CH₃)₂-]_nO-Si(CH₃)₂(CH=CH₂), where n=1280÷1300, a weight part of vinyl groups constitutes 0.08÷0.095 wt %, dynamic viscosity is 54000÷55000 cp; a silicone resin of the general formula {[(CH₃)₃SiO_1/2]_x[SiO₂]₁[(CH₃)₂SiO]_y[CH₃VinSiO]_z}, where x=0.9÷1.2, y=0÷0/4, z=0.1÷0.4; halloysite and a filling agent. As the filling agent used is aluminium oxide, metallised with iron.

EFFECT: invention ensures obtaining the heat resistant silicone composite material, possessing higher adhesion to metal at a temperature of 500°C.

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Description

The invention relates to silicone composite materials, which are obtained by the polyaddition reaction and find their application for heat-resistant protective coatings with adhesion to metals (various grades of steel, aluminum, titanium, etc.).

Silicone composite materials obtained by the polyaddition reaction are widely used as coatings, adhesives, sealing materials in products for various purposes. The specific operating conditions of a product, for example, vibration, mechanical, thermal loads, the undesirability of the presence of solvents, impose increased requirements for the adhesion of the material used.

American patents describe adhesion methods to glass, metals, and plastics, in which at least 5 to 50 parts by weight of silicone resins consisting of SiO _4/2 units are used in the silicone composite materials obtained by the polyaddition reaction and RSiO _3/2 , where R = monovalent hydrocarbon group: methyl, ethyl, propyl, vinyl, allyl and others (Patent US 5994461, IPC C08L 83/04, 11/30/1999; Patent US 6004679, IPC B32B 9/04, December 21, 1999).

It is known to use halloysite in the composition of Tikolak paint, which protects against electromagnetic radiation in a wide frequency range, having adhesive strength when tearing to various materials from 5 to 15 kg / cm ² [nanonewsnet, https://www.corporacia.ru/news /news/show/143.htn].

Known silicone composite material obtained by the polyaddition reaction, consisting of 100 parts by weight a liquid mixture of polyorganosiloxanes, (35 wt.% polyorganosiloxane resin, consisting of 30 mol.% units of SiO _4/2 , 68.4 mol.% (CH ₃ ) ₃ SiO _1/2 and 1.6 mol.% (CH ₂ = CH) (CH ₂ ) ₂ SiO _1/2 , and 65 wt.% Polyorganosiloxane with terminal vinyl groups having a viscosity of 2000 cP), 20 wt.h. silica microparticles treated with hexamethyldisilazane 200 (a surface-modified aerosil 200 analog), organosilicon siloxane and a catalyst containing platinum (Patent US 5994461, IPC C08L 83/04, 11/30/1999). The materials obtained in accordance with this formulation have a peel adhesion to metal (steel) of 15 kg / cm ² .

A known composition of a paint and varnish material for a heat-resistant coating, obtained on the basis of a polyphenylsiloxane resin modified with an acrylate copolymer, containing heat-resistant pigments (aluminum powder) and a filler that increases heat resistance, ground mica with a particle size of not more than 160 microns or ground mica in a mixture containing up to 50% silicon-iron powder or microtalc, solvent. The adhesion of films at room temperature to a metal substrate is 1 point (Patent RU 2182582, IPC C09D 183/04, 5/08, 05/20/2002).

A known composition of a paint and varnish material for a heat-resistant coating, obtained on the basis of polyorganosiloxane resin, pentaphthalic varnish and isobutyl methacrylate polymer, containing heat-resistant pigment (aluminum powder), filler - porous silicate or a mixture of mica with porous silicate (perlite or kieselguhr), solvent. The adhesion of the films at room temperature to the metal substrate is 1 point (Patent RU 2378309, IPC C09D 183/06, C09D 5/08, 01/10/2010).

The closest to the recipe and accepted for the prototype is a silicone composite material obtained by the polyadimethylsiloxane-based polyaddition reaction with vinyl terminal groups: (CH ₂ = CH) (CH ₃ ) ₂ Si [OSi (CH ₃ ) ₂ ] _n OSi (CH ₃ ) ₂ (СН = СН ₂ ), (n = 1280 ÷ 1300, the mass fraction of vinyl groups is 0.08 wt.%, Dynamic viscosity is 92822 ÷ 93000 cP), organosilicon resin MQDD ^vin {[(СН ₃ ) ₃ SiO _{1 / 2} ] _x [SiO ₂ ] ₁ [(CH ₃ ) ₂ SiO] _y [CH ₃ VinSiO] _z }, where x = 0.9 ÷ 1.2, y = 0 ÷ 0.4, z = 0.1 ÷ 0.4), organopolysiloxane, a catalyst containing platinum and halloysite in an amount of 5 to 25 m ac.h. per 100 parts by weight siloxane binder (Patent RU 2401850, IPC C08L 83/04; C08L 83/07, 10/20/2010]. Materials obtained in accordance with this formulation have adhesion to tearing to metal: steel - from 19.7 to 35.8 kg / cm ² (150 ° C / 0.5-1 h), aluminum - from 20.7 to 37.6 kg / cm ² (150 ° C / 0.5-1 h).

The objective of the present invention is to improve the adhesion of silicone composite materials obtained by the polyaddition reaction to metals used as coatings, adhesives, sealing materials in products for various purposes, namely that the silicone composite material having increased adhesion, does not contain a solvent, obtained based on polydimethylsiloxane with terminal vinyl groups of the general formula

(CH ₂ = CH) (CH ₃ ) ₂ Si- [O-Si (CH ₃ ) ₂ -] _n O-Si (CH ₃ ) ₂ (CH = CH ₂ ), (α, ω-FDPMS)

where n = 1280 ÷ 1300, the mass fraction of vinyl groups is 0.08 ÷ 0.095 wt.%, dynamic viscosity 54000 ÷ 55000 cP, contains from 6.81 to 8.96 wt.h. type MQ silicone resin (MQD ^vin ) of the general formula

{[((CH ₃ ) ₃ SiO _1/2 ] _x [SiO ₂ ] ₁ [(CH ₃ ) ₂ SiO] _y [CH ₃ VinSiO] _z }, where x = 0.9 ÷ 1.2, y = 0 ÷ 0.4, z = 0.1 ÷ 0.4 (based on 17.01-22.42 parts by weight of polymer);

from 3.90 to 7.50 parts by weight halloysite (calculated on 17.01-22.42 parts by weight of polymer) and from 62.34 to 71.42 parts by weight filler, increasing adhesion to the metal, which is used as aluminum oxide, metallized with iron with an iron content of at least 25 wt.% calculated on 17.01-22.42 wt.h. polymer, while the composite material retains adhesion to the metal at a temperature of more than 500 ° C.

This task is achieved by the fact that in the silicone composite material obtained on the basis of polydimethylsiloxane with terminal vinyl groups (17.01-22.42 parts by weight of polymer) of the general formula

(CH ₂ = CH) (CH ₃ ) ₂ Si- [O-Si (CH ₃ ) ₂ -] _n O-Si (CH ₃ ) ₂ (CH = CH ₂ ), (α, ω-FWDMS), where n = 1280 ÷ 1300, the mass fraction of vinyl groups is 0.08 ÷ 0.095 wt.%, Dynamic viscosity 54000 ÷ 55000 cP,

- 6.81-8.96 parts by weight type MQ silicone resin (MQD ^vin ) of the general formula

{[((CH ₃ ) ₃ SiO _1/2 ] _x [SiO ₂ ] ₁ [(CH ₃ ) ₂ SiO] _y [CH ₃ VinSiO] _z },

where x = 0.9 ÷ 1.2, y = 0 ÷ 0.4, z = 0.1 ÷ 0.4;

- from 3.90 to 7.50 parts by weight halloysite, additionally introduced from 62.34 to 71.42 parts by weight filler - aluminum oxide metallized with iron with an iron content of at least 25 wt.%.

The vulcanization of the silicone composite material is carried out using a crosslinking agent, oligomethylhydride siloxane, containing 0.50-0.62 wt.% Si-H groups, having a viscosity of 70 cP, platinum or a catalyst (for example, Spyer catalyst (0.1 M H ₂ PtCl solution ₆ in isopropyl alcohol) or a platinum complex compound).

The proposed method allows to improve self-adhesion to protected substrates, especially to metals and at the same time increase the heat resistance of silicone composite materials obtained by the polyaddition reaction and containing from 3.90 to 7.50 wt.h. halloysite and from 62.34 to 71.42 parts by weight a new filler - aluminum oxide, metallized with iron, 17.01-22.42 wt.h. siloxane polymer.

The essence of the claimed invention is illustrated by the following examples.

Example 1 (prototype).

Silicone composite material is prepared by mixing 59.52 wt.h. vinyl-terminated polydimethylsiloxane containing 0.095 wt.% vinyl groups having a dynamic viscosity of 54500 cP, with 23.81 wt.h. MQD ^vin organosilicon resin, the mixture is kept at a temperature of 80 ÷ 100 ° C for at least 3 hours, cooled to room temperature, 16.67 parts by weight are added. halloysite and homogenize the mixture by grinding on a mechanical mortar. Vulcanization of the composition can occur at room temperature, the optimal physical and mechanical properties are achieved at 120 ° C / 1 h or 150 ° C / 0.5-1 h.

The adhesion at separation, kg / cm ² , is: to steel - 30.8 (150 ° C / 0.5-1 h), to aluminum - 32.3 (150 ° C / 0.5-1 h) (separation cohesive), with a trellised incision (coating thickness not more than 0.2 mm) is: steel - 1 point (150 ° C / 0.5-1 h) and 6 points (500 ° C / 0.6 h).

Example 2

Silicone composite material is prepared by mixing 22.42 wt.h. vinyl-terminated polydimethylsiloxane containing 0.095 wt.% vinyl groups having a dynamic viscosity of 54880 cP, with 8.96 wt.h. silicone resin MQD ^vin , the mixture is kept at a temperature of 80 ÷ 100 ° C for at least 3 hours, cooled to room temperature, add 6.28 wt.h. halloysite and 62.34 parts by weight filler (aluminum oxide, metallized with iron with an iron content of 25 wt.%) and homogenize the mixture by grinding on a mechanical mortar. Vulcanization of the composition takes place in the presence of oligomethylhydridosiloxane containing 0.58 wt.% Si-H groups having a viscosity of 70 cP and 1 wt.h. Spier catalyst or platinum complex compound. Vulcanization of the composition can occur at room temperature, the optimal physical and mechanical properties are achieved at 120 ° C / 1 h or 150 ° C / 0.5-1 h. Adhesion at separation, kg / cm ² , is: steel - 35.7 ( 150 ° C / 0.5-1 h); aluminum - 37.5 (150 ° С / 0.5-1 h) (cohesive separation), with a trellised incision (coating thickness not more than 0.2 mm): steel - 1 point (150 ° С / 0.5-1 h) and 1 point (550 ° C / 0.6 h).

Example 3

Silicone composite material is prepared and vulcanized similarly to Example 2 by mixing 17.86 parts by weight vinyl-terminated polydimethylsiloxane containing 0.095 wt.% vinyl groups having a dynamic viscosity of 54000 cP, with 7.14 wt. silicone resin MQD ^vin , 7.5 parts by weight halloysite and 67.5 parts by weight filler (aluminum oxide metallized with iron with an iron content of 25 wt.%).

The adhesion at separation, kg / cm ² , is: steel - 42.0 (150 ° C / 0.5-1 h); aluminum - 44.2 (150 ° C / 0.5-1 h) (cohesive separation), with a trellised incision (coating thickness not more than 0.2 mm) is: steel - 1 point (150 ° C / 0.5- 1 h) and 1 point (550 ° C / 0.6 h).

Example 4

Silicone composite material is prepared and cured in the same manner as in Example 2 by mixing 18.55 parts by weight. vinyl-terminated polydimethylsiloxane containing 0.095 wt.% vinyl groups having a dynamic viscosity of 54880 cP, with 7.42 wt. organosilicon resin MQD ^vin , 3.90 parts by weight of halloysite and 70.13 parts by weight of filler (aluminum oxide metallized with iron with an iron content of 20 wt.%).

The adhesion at separation, kg / cm ² , is: steel - 32.0 (150 ° C / 0.5-1 h); aluminum - 35.0 (150 ° C / 0.5-1 h) (cohesive separation), with a trellised incision (coating thickness not more than 0.2 mm) is: steel - 1 point (150 ° C / 0.5- 1 h) and 2 points (600 ° C / 0.6 h).

Example 5

Silicone composite material is prepared and cured in the same manner as in Example 2 by mixing 18.08 wt.h. vinyl-terminated polydimethylsiloxane containing 0.095 wt.% vinyl groups having a dynamic viscosity of 55,000 cps, with 7.24 wt.h. organosilicon resin MQD ^vin , 6.33 parts by weight of halloysite and 68.35 parts by weight of filler (aluminum oxide, metallized with iron with an iron content of 65 wt.%).

The adhesion at separation, kg / cm ² , is: steel - 37.0 (150 ° C / 0.5-1 h); aluminum - 38.8 (150 ° C / 0.5-1 h) (cohesive separation), with a trellised incision (coating thickness not more than 0.2 mm) is: steel - 1 point (150 ° C / 0.5- 1 h) and 1 point (550 ° C / 0.6 h).

Example 6

Silicone composite material is prepared and vulcanized in the same manner as in Example 1 by mixing 17.01 parts by weight of vinyl-terminated polydimethylsiloxane containing 0.095 wt.% vinyl groups having a dynamic viscosity of 54900 cP (54000-55000 cP), with 6.81 wt. organosilicon resin MQD ^vin , 4.76 wt.h. halloysite and 71.42 parts by weight filler (aluminum oxide, metallized with iron with an iron content of 65 wt.%).

The adhesion at separation, kg / cm ² , is: steel - 37.0 (150 ° C / 0.5-1 h); aluminum - 38.8 (150 ° C / 0.5-1 h) (cohesive separation), with a trellised incision (coating thickness not more than 0.2 mm) is: steel - 1 point (150 ° C / 0.5- 1 h) and 2 points (600 ° C / 0.6 h).

Claims (1)

A method for improving the adhesion to metals of silicone composite materials obtained by the polyaddition reaction, namely, that the silicone composite material having increased adhesion, does not contain a solvent, obtained on the basis of polydimethylsiloxane with vinyl terminal groups of the general formula
(CH ₂ = CH) (CH ₃ ) ₂ Si- [O-Si (CH ₃ ) ₂ -] _n O-Si (CH ₃ ) ₂ (CH = CH ₂ ) (α, ω-DVDPMS),
where n = 1280 ÷ 1300, the mass fraction of vinyl groups is 0.08 ÷ 0.095 wt.%, dynamic viscosity 54000 ÷ 55000 cP, contains from 6.81 to 8.96 wt.h. organosilicon resin of the General formula
{[((CH ₃ ) ₃ SiO _1/2 ] _x [SiO ₂ ] ₁ [(CH ₃ ) ₂ SiO] _y [CH ₃ VinSiO] _z },
where x = 0.9 ÷ 1.2, y = 0 ÷ 0.4, z = 0.1 ÷ 0.4, calculated on 17.01-22.42 wt.h. polymer, from 3.90 to 7.50 parts by weight halloysite based on 17.01-22.42 parts by weight polymer and from 62.34 to 71.42 parts by weight filler, increasing adhesion to the metal, which is used as aluminum oxide, metallized with iron with an iron content of at least 25 wt.% calculated on 17.01-22.42 wt.h. polymer, while the composite material retains adhesion to the metal at a temperature of more than 500 ° C.