RU2487149C2 - Hardening mixture - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: hardening mixture for vulcanising materials based on liquid siloxane rubber consists of two prepared and separately stored components (component No1 and component No2) which are joined when mixed before adding to the siloxane material to be hardened; component No1 contains ethyl silicate, an organic tin salt and polyethylene polyamine; component No2 contains polymethylsiloxane, active silicon dioxide and organochlorosilane.

EFFECT: obtaining a strong and elastic vulcanisate while cutting duration of the vulcanisation process.

2 cl, 4 tbl, 22 ex

Description

The proposed curing mixture is a composition for the vulcanization of materials based on siloxane rubbers and relates to the field of curing catalytic mixtures for sealants, compounds, adhesives, film coating compositions and impregnating compositions based on siloxane. There are various known activators of "cold" curing of both domestic and foreign production, the basis of which are alkyl silicates mixed with organic salts of tin (D.A. Kardashov, A.P. Petrova. Polymer adhesives. M: "Chemistry", 1983) . The indicated hardeners of complex composition include standard organotin catalysts K-1 (TU 6-02-1-011-89), K-18 (TU 6-02-805-78), K-21 (TU 38.303-04-05 -90). Another group of materials are solutions of aminoalkylethoxysilanes in ethyl silicate, for example, the traditional domestic catalyst K-68 (TU 38.303-04-05-90). Catalyst K-68 is a solution of aminopropyltriethoxysilane in ethyl silicate.

Various hardeners are known for liquid siloxane rubbers based on salts of manganese, lead and titanium (Encyclopedia of Polymers T.1 p.783-784, p.1011-1015, p.1076-1082 M. Soviet Encyclopedia 1972, Chemical Encyclopedia T. 1 534-537, T. 2 p. 438-439, p. 509-516, p. 1044-1045 M .: Soviet Encyclopedia, 1990). However, the vulcanizates of siloxane materials cured by all of the above systems are not strong enough. Another group of curing materials is alkyl (aryl) acetoxysilanes, which can give vulcanizate only in relatively thin layers (2-3 mm) and impart adhesion properties to the vulcanizates with respect to various materials. As an example, catalyst K-10C (TU 6-02-874-79) can be mentioned. A serious obstacle to the widespread use of these hardeners is the diffusion mechanism of their action, associated with the need for air moisture to penetrate into the layer of viscous fluid material for hydrolytic interaction with the hardener, as well as with the need for back diffusion of hydrolysis products from the vulcanizate layer. Durable vulcanizate is formed by the combined use of ethyl silicate, an organotin catalyst, alkyl (aryl) acetoxysilane as a hardener (RF patent 2052475). However, in this case, the curing process is delayed up to 3 days, and the resulting vulcanizate is not sufficiently elastic.

Known curing mixture for liquid siloxane rubbers with terminal silanol groups (RF patent 2010820), closest to the claimed composition. The mixture includes ethyl silicate, an organic tin salt and organochlorosilane in the calculation of 0.1-0.5 parts by weight. per 100 parts by weight ethyl silicate. The use of this mixture in practice in industrial conditions is difficult due to the high reactivity and easy hydrolysis of chlorosilanes with air moisture. This is due to the low stability of the curing mixture under long-term storage and its rapid deactivation during hydrolysis. A significant excess of ethyl silicate used in the mixture seems to be unjustified, since the vulcanization process and the set of final physical and mechanical properties are delayed up to 7-10 days, which is practically impractical. Another negative consequence of excess ethyl silicate is the low elasticity of the final vulcanization product, which devalues the practical applicability of the material. However, as follows from the tables placed in the patent of the Russian Federation 2010820, ultimately, it is possible to obtain a vulcanizate with significant mechanical strength.

An object of the present invention is to provide a curing mixture that provides the strength of the resulting siloxane rubber vulcanizate with an increase in the elasticity of the vulcanizate, a significant reduction in the duration of the vulcanization process, and increased stability of the catalyst mixture during storage. The problem is solved by adding to the total catalytic mixture an amine selected from polyethylene polyamine (PEPA), as well as polymethylsiloxane and surface-active silicon dioxide.

Upon receipt of the curing mixture, two compositions are preliminarily prepared (hereinafter component No. 1 and component No. 2):

- component No. 1 includes: ethyl silicate-40 or ethyl silicate-32 - 100 parts by weight; organic tin salt selected from tin octoate, tin diethyl dicaprylate, 10-15 parts by weight; an amine selected from PEPA - 7-15 parts by weight;

- component No. 2 includes: polymethylsiloxane - 100 parts by weight; active silicon dioxide selected from Aerosil-175, Aerosil-300, white carbon black U-333, 20-30 parts by weight; organochlorosilane selected from methylphenyldichlorosilane and dimethyldichlorosilane - 0.5-1.5 parts by weight

The following chemical products are used in the curing mixture:

- ethyl silicate-40, a product of partial hydrolysis of tetraethoxysilane according to GOST 26371-84;

- Sn tin octoate (OOCC ₇ H ₁₅ ) ₂ according to TU 6-02-539-75;

- tin diethyldicaprylate according to TU 6-02-1-013-89;

- PEPA according to TU 2413-357-00203447-99;

- white soot U-333 TU 2168-016-00204872-2003;

- PMS-50 GOST 13032-77;

- methylphenyldichlorosilane TU 6-02-629-75;

- dimethyldichlorosilane GOST 16485-87;

- Aerosil-175 GOST 14922-77;

- Aerosil-300 GOST 14922-77.

Component No. 1 and component No. 2 are mixed in a mass ratio of from 5: 1 to 1: 1. The composition of component No. 1 is given in table 1, the composition of component No. 2 is given in table 2, the ratio of component No. 1 and component No. 2, as well as the total composition of the curing mixture are given in table 3. Some physico-mechanical and technological properties of vulcanizates obtained on the basis of the claimed composition of the curing mixture are shown in table 4. Specific examples of the curing mixture of the present method are given below.

Table 1 The composition of component No. 1 Example Ethylsilicate ETS-40 Tin Octoate Tin diethyl dicaprylate PEPA one one hundred 10 7 2 one hundred 12 10 3 one hundred fourteen eleven four one hundred fifteen 12 5 one hundred fifteen fifteen 6 one hundred eleven 10 7 one hundred 10 fifteen 8 one hundred fifteen 9 9 one hundred 12 12 10 one hundred 12 12

table 2 The composition of component No. 2 Example PMS-50 PMS-300 Aerosil-175 White soot U-333 Aerosil-300 Dimethyl dichlorosilane Methylphenyl dichlorosilane one one hundred twenty 0.5 2 one hundred twenty 1,0 3 one hundred twenty 1,2 four one hundred thirty 1,5 5 one hundred thirty 1,0 6 one hundred thirty 0.5 7 one hundred 10 fifteen 1,0 8 one hundred 12 eighteen 1,2 9 fifty fifty 25 1,0 10 thirty 70 22 1,5

Table 3 The total composition (curing mixture Example Compo
Nent No. 1 (in accordance with table 1) Compo
Nent No. 2 (in accordance with table 2) Weight ratio comp 1: comp 2 ETS-40 Tin Octoate Diethyl dicapri
lat tin PEPA PMS-50 PMS-300 Silica Chlorsi
lan one one one 5: 1 one hundred 10 7 twenty four 0.1 2 one 5 5: 2 one hundred 12 10 40 8 0.4 3 2 6 5: 3 one hundred fourteen eleven 60 12 0.7 four four 7 5: 4 one hundred fifteen 12 80 24 1,2 5 6 9 5: 5 one hundred fifteen fifteen one hundred thirty 1,0 6 7 10 5: 2 one hundred eleven 10 40 12 0.2 7 3 5 5: 1 one hundred 10 fifteen twenty 5 0.2 8 5 2 5: 3 one hundred fifteen 9 60 eighteen 0.4 9 9 3 5: 2 one hundred 12 12 twenty twenty 10 0.4 10 10 four 5: 1 one hundred 12 12 6 fourteen 5 0.3 eleven 8 9 5: 5 one hundred 10 10 fifty fifty thirty 1,0 12 10 8 5: 4 one hundred 10 10 fifty 80 twenty 0.8

Examples of the curing mixture

Obtaining component No. 1

Example 1

To 100 g of ethyl silicate-40, 10 g of tin octoate was added with stirring, then 7 g of PEPA was added to the mixture. The mixture is placed in a tightly closed container, stirred by shaking for another 3-4 minutes, stored separately from component No. 2.

Example 2

15 g of tin octoate are added to 100 g of ethyl silicate-40 with stirring, then 15 g of PEPA are added to the mixture. The mixture is placed in a tightly closed container, stirred by shaking for another 3-4 minutes, stored separately from component No. 2.

Example 3

To 100 g of ethyl silicate-40, 10 g of tin diethyl dicaprylate was added with stirring, then 15 g of PEPA was added to the mixture. The mixture is placed in a tightly closed container, stirred by shaking for another 3-4 minutes, stored separately from component No. 2.

Example 4

To 100 g of ethyl silicate-40, 12 g of tin diethyl dicaprylate was added with stirring, then 12 g of PEPA was added to the mixture. The mixture is placed in a tightly closed container, stirred by shaking for another 3-4 minutes, stored separately from component No. 2.

Obtaining component No. 2

Example 5

To 100 g of PMS-50 add 20 g of Aerosil-175, mix for 2-3 minutes manually, preventing spraying of Aerosil. Stir the suspension for another 2-3 minutes using an anchor mixer. Lastly, 0.5 g of dimethyldichlorosilane is added to the suspension, carefully mixed for 30-40 s. The whole mixture (suspension) is transferred to a tightly closed container, stored separately from component No. 1.

Example 6

To 100 g of PMS-50 add 30 g of Aerosil-175, mix for 2-3 minutes manually, preventing spraying of Aerosil. Stir the suspension for another 2-3 minutes using an anchor mixer. Lastly, 1.5 g of dimethyldichlorosilane is added to the suspension, carefully mixed for 30-40 s. The whole mixture (suspension) is transferred to a tightly closed container, stored separately from component No. 1.

Example 7

To 100 g of PMS-300 add 30 g of Aerosil-300, mix for 2-3 minutes manually, preventing spraying of Aerosil. Stir the suspension for another 2-3 minutes using an anchor mixer. Lastly, 0.5 g of methylphenyldichlorosilane is added to the suspension, carefully mixed for 30-40 s. The whole mixture (suspension) is transferred to a tightly closed container, stored separately from component No. 1.

Example 8

To a mixture consisting of 50 g of PMS-50 and 50 g of PMS-300, add 18 g of soot, and then, with stirring, 12 g of Aerosil-175, mix for 2-3 minutes manually, preventing spraying of Aerosil and white soot. Stir the suspension for another 2-3 minutes using an anchor mixer. Lastly, 1 g of methylphenyldichlorosilane is added to the suspension, and carefully mixed for 30-40 s. The whole mixture (suspension) is transferred to a tightly closed container, stored separately from component No. 1.

Getting ready to use curing mixture

Example 9

To 20 g of component No. 1 (table 1, example 1) add 4 g of component No. 2 (table 2, example 1), mix on an anchor mixer for 2-3 minutes. The mixture is transferred to a separate container with a label. The tests are carried out by mixing with a standard mixture comprising 100 parts by weight low molecular weight rubber SKTN-B, 20 g PMS-50 and 40 g active silicon dioxide.

Example 10

To 20 g of component No. 1 (table 1, example 6) add 20 g of component No. 2 (table 2, example 9), mix on an anchor mixer for 2-3 minutes. The mixture is transferred to a separate container with a label. The tests are carried out by mixing with a standard mixture comprising 100 parts by weight low molecular weight SKTN-B, 20 g PMS-50 and 40 g active silicon dioxide.

Example 11

To 100 g of component No. 1 (table 1, example 5) add 12 g of component No. 2 (table 2, example 2), mix on an anchor mixer for 2-3 minutes. The mixture is transferred to a separate container with a label. The tests are carried out by mixing with a standard mixture comprising 100 parts by weight low molecular weight SKTN-B, 20 g PMS-50 and 40 g active silicon dioxide.

Example 12

To 20 g of component No. 1 (table 1, example 8) add 20 g of component No. 2 (table 2, example 9), mix on an anchor mixer for 2-3 minutes. The mixture is transferred to a separate container with a label. The tests are carried out by mixing with a standard mixture comprising 100 parts by weight low molecular weight SKTN-B, 20 g PMS-50 and 40 g active silicon dioxide.

Table 4 summarizes the results of the interaction of the inventive curing mixture with a vulcanizable siloxane mixture, including SKTN-B selected as model rubber, 100 parts by weight, PMS-50 20 parts by weight. and white soot U-333.

Table 4 The main properties of vulcanizates, cured by the inventive mixture Example The composition of the mixture (No. according to table 3) The ratio of rubber composition: hardener The gelation time, min Full cure time, hour Degree of fluidity Tensile strength, MPa Relative extension, % one one 100: 10 eighteen 26 viscous flow 3,1 204 2 3 100: 8 25 24 fluid 3.3 220 3 6 100: 6 21 24 viscous flow 3.2 235 four 7 100: 3 45 32 viscous flow 2.7 210 5 10 100: 2 65 39 viscous flow 3.0 206 6 8 100: 5 32 24 viscous flow 3.2 215 7 9 100: 7 27 24 viscous flow 2,8 225 8 12 100: 10 twenty 22 fluid 2.9 240 9 four 100: 12 fourteen 19 fluid 3.3 260 10 5 100: 8 26 24 viscous flow 3,1 227 eleven 2 100: 5 31 24 viscous flow 3.15 220 12 3 100: 7 34 twenty fluid 2.85 250 13 2 100: 5 36 19 viscous flow 3.4 234 fourteen four 100: 8 29th 17 fluid 3.05 262 fifteen eleven 100: 10 twenty 19 fluid 3.45 244 16 8 100: 7 22 24 viscous flow 3.15 226 17 10 100: 50 110 80 fluid 5,0 80 eighteen Example 3 100: 50 80 66 fluid 3.0 70 prototype 19 Prototype Example 6 100: 30 132 95 fluid 3.2 102 twenty Prototype Example 5 100: 30 68 82 fluid 5.5 84 21 Catalyst K-18 100: 5 60 24 viscous flow 1,2 135 22 Catalyst K-21 100: 5 60 24 viscous flow 1.4 140

The analysis of the data given in table 4, indicates the advantage of the claimed curing mixture in comparison with the curing mixture of the prototype:

- the achieved gelation time is less than for the prototype, but if necessary, can be significantly increased by simply reducing the content of the inventive curing mixture in relation to the amount of siloxane rubber;

- significantly less time to achieve physico-mechanical and operational parameters, including the claimed curing mixture;

- significantly higher value of elasticity. In this case, the strength properties of the vulcanizate are slightly lower than in the prototype, but their values are quite sufficient for most of the technical problems to be solved.

The inventive curing mixture is made by mixing all of the listed components, prepared in advance in the form of component No. 1 and component No. 2. In accordance with the test results, it was found that the optimum properties of the curing mixture are manifested provided that the mixture contains component No. 1 and component No. 2 in a ratio of 5: 2 to 5: 3. In this case, the best ratio between the rubber composition and the curing mixture should be considered an interval from 100: 5 parts by weight up to 100: 10 parts by weight Only the claimed combination of components, the sequence of their preliminary mixing allows to achieve high efficiency of the curing mixture. The advantages of the inventive curing mixture in comparison with the prototype is also higher storage stability and lower corrosion activity. The effectiveness of the inventive curing mixture is determined both by the action of the polyethylene-polyamine component of component No. 1, and by the action of the organochlorosilane component of component No. 2. The substances that make up component No. 1 do not interact with each other and can be stored for a long time in a closed volume of a sealed container. The substances that make up component No. 2 do not interact with each other and can be stored for a long time in a closed volume of a sealed container. The presence in the component No. 2 of surface-active silicon dioxide in combination with polyalkoxysiloxane allows the chlorosilane component to be preserved from decomposition and hydrolysis. Thus, the storage stability of the curing mixture is higher than that of the mixture of the prototype. Its full activity is manifested from the moment of mixing component No. 1 with component No. 2 and adding the mixture to the curable rubber composite.

Thus, it was possible to create a curing mixture that provides the necessary strength of the vulcanizate of siloxane rubber while increasing the elasticity of the vulcanizate, significantly reducing the duration of the vulcanization process, increasing stability during storage, and therefore the reliability of the inventive curing mixture during use. Thus, the technical problem of the present invention should be considered solved.

Claims (2)

1. The curing mixture for the vulcanization of materials based on liquid siloxane rubbers, including ethyl silicate, an organic tin salt, organochlorosilane, characterized in that it further comprises polyethylene polyamine, polymethylsiloxane and active silicon dioxide in the following ratio, wt.h .:
Ethyl silicate one hundred Organic Tin Salt 10-15 Organochlorosilane 0.1-1.5 Polyethylene polyamine 7-15 Polymethylsiloxane 20-100 Silica 4-30,
moreover, the curing mixture consists of two pre-prepared and separately stored components (component No. 1 and component No. 2), joined when mixed before adding to the cured siloxane material, where component No. 1 includes ethyl silicate, an organic tin salt and polyethylene polyamine, component No. 2 includes polymethylsiloxane , active silica and organochlorosilane. 2. The curing mixture according to claim 1, characterized in that the mass ratio of component No. 1 and component No. 2 lies in the range from 5: 1 to 5: 5.