DE19711519A1 - Foamable organosiloxane composition - Google Patents

Abstract

The present invention relates to methods for producing foamable organosiloxane compositions having improved fire-resistance ratings and radiation resistance. This foamable organosiloxane composition comprises a liquid organosiloxane rubber (OR), an organosilicon cross-linking agent (CA) and a carbonate filler (CF). This composition uses as OR a rubber or mixture of rubbers corresponding to general formula (I) where R, R<1> and R<2> each represent a lower alkyl radical with 1 to 6 carbon atoms or an aryl radical with 6 to 10 carbon atoms; n is an integer between 10 and 1500 while k and l are integers between 0 and 500. This composition uses as CA a compound of the general formula R<3>SiX3 where R<3> is an alkyl radical with 1 to 6 carbon atoms, an aryl radical with 6 to 10 carbon atoms, an arylalkyl radical with 7 to 12 carbon atoms or an alkenyl radical with 2 to 4 carbon atoms. X represents halogen or a compound of the general formula OC(O)R<4> where R<4> is an alkyl radical with 1 to 6 carbon atoms or an aryl radical with 6 to 12 carbon atoms. This composition finally uses as CF one or more substances chosen from the compounds corresponding to the general formula MxCO3 where M is NaH, NH4, Na, K, Ca, Mg or Ba, and x is 1 or 2. Those components are selected according to the following amounts in parts per weight: 100 of OR; from 5 to 30 of CA; and from 20 to 120 of CF.

Description

The invention relates to the processes for the preservation of foamable organosiloxane Compositions with improved characteristics for fire and radiation resistance.

The foamable organosiloxane composition contains the liquid organosiloxane rubber (OK), the organosilicon crosslinking agent (CA) and the carbonate filling (KH). As (OK) contains the rubber or a mixture of rubbers having the general formula such as follows:

Where:
R, R¹, R²- is the lowest alkyl radical having 1 to 6 carbon atoms or an aryl radical having 6 to 10 carbon atoms and
n - an integer from 10 to 1500 and
k, l - integers from 0 to 500;
(n + k + l) - an integer from 10 to 1500 as well
m is an integer from 0 to 10;
as (CA) it contains a compound with the general formula:
R³SiX₃, where:
R³ - an alkyl radical having 1 to 6 carbon atoms or an alkenyl radical having 2 to 4 carbon atoms,
× - a halogen or a compound having the general formula OC (O) R⁴ where:
R⁴ is an alkyl radical of 1 to 6 carbon atoms or an aryl radical of 6 to 12 carbon atoms;
as (KH) it contains at least one substance from the compounds with the general formula:
MxCO₃ where:
M - NaH, NH₄, Na, Ca, Mg, Ba as well
x - 1 or 2;
this is the case for the following ratio of components (in mass proportions):
(OK) - 100
(CA) - 5-30
(KH) - 20-120

Field of engineering

The present invention is one of the methods for producing foamable To count organosiloxane compositions, which are used to isolate different objects Application, but with improved properties such as fire resistance and Radiation resistance.

Previous state of the art

Foaming organosiloxane compositions which are known as a mixture of Organosiloxanes, crosslinking agents and foam generators are produced.

The molding of the foam structure of these materials results from the reaction Organohydridsiloxanen whose molecules consist of at least 2 groups ≅ S-H, with Water or compounds, in turn, the groups such as ≅ SiOH (US, A, 5238967) or ≅ C-OH (US, A, 5356940).

These reactions take place under catalytic action of the platinum compounds (US, A, 5216037) or bases (US, A, 4987155).

To achieve such properties as fire resistance serve several methods, the Most important of these are the introduction of platinum into the compounds in the crowd, the that of the catalytic (US, A, 5216037) significantly exceeds. Another method exists in that conventional antipyrenes (US, A, 4695597) are introduced into the composition. The foam elastomers produced thereby are practically incombustible. However, the use becomes of known non-combustible foam elastomers particularly difficult that the expensive platinum compounds to be introduced into the mixture.  

In addition, the foaming of Organosiloxankompositionen by means of hydrogen which develops as the reaction progresses during mixing of the components. It It is known that the hydrogen with the oxygen contained in the air explosive mixtures with concentrations in a wide range can form.

Accordingly, the preparation of the known foam-forming organosiloxane requires Compositions special security measures. The participation of hydrogen in the Structure formation of known foam elastomers as indispensable condition leaves the the latter are not used for the isolation of any objects where the resulting foam elastomer with heated surfaces, sparks, open flame in contact can come.

Most comparable to the present invention is the foam-forming organosiloxane Composition consisting of liquid organosiloxane rubber, organosilicon Crosslinking agent and carbonate filler (US, A, 4705810).

In the known composition, the formation of a porous structure by means of Carbon dioxide (CO₂), which is obtained in the reaction of calcium carbonate with carboxylic acid. However, the known composition contains compounds with groups ≅ SiH, which with Carboxylic acids can react under evolution of hydrogen. Furthermore, the foaming takes place the known composition at a temperature in the range of 150 to 180 ° C, what in turn promotes the evolution of hydrogen.

Although the risk of formation of an explosive mixture in the production reasonably reduced this known foaming organosiloxane composition.

However, the use of this composition is accompanied by the foaming Hydrogen evolution and high temperatures difficult. Furthermore, one misses the known compositions satisfying fire resistance and radiation resistance.  

The latter circumstance complicates the use of the known foam-forming organosiloxane Composition for the production of the insulating coatings or the encapsulation of the Radionuclide contaminated objects (storages or Peganum Harmala the radioactive waste, including those that are dividing isotopes U-235 and Pu-239 contain, by accidents at nuclear objects contaminated rooms and terrain).

The insulating materials used for these purposes must not only be incombustible, but also as little flammable and explosive gases under the action large radiation doses while retaining the original shape and dimensions. In some cases, these substances are said to be produced by the decomposition of dividing isotopes neutrons can absorb.

Disclosure of the invention

The problem whose solution has been set with the present invention consists in the development of a foam-forming organosiloxane composition, which as incombustible material would be used for insulation, the formation of an explosive Exclude and improve the mixture at the stage of formation of the foam structure Fire resistance and radiation resistance would have.

The purpose of the present invention is the incombustibility of the composition resulting materials, reduction of gas evolution, maintaining the structure and Form during irradiation and lack of hydrogen evolution in formation of the Foam structure.

Another goal is to increase the absorption capacity of the neutrons of the materials that arise from foam-forming organosiloxane compositions.

The technical purposes mentioned above can be achieved by using the foam-forming organosiloxane composition consisting of the liquid organosiloxane rubber, organosilicon crosslinking agent and carbonate filler,
as organosiloxane rubber according to the invention contains rubber or a rubber mixture according to the following general formula:

where R, R¹, R² is - lowest alkyl radical of 1-6 carbon atoms or aryl radical of 6-10 Carbon atoms, n - an integer from 10 to 1500, k, l - integers from 0 to 500, the Sum (n + k + l) - an integer from 10 to 1500, m - an integer from 0 to 10, as organosilicon crosslinking agent, the compound according to the general formula:

R³SiX₃ or mixtures thereof where

R³ - alkyl radical having 1-6 carbon atoms, aryl radical having 6-10 carbon atoms, arylalkyl radical having 7-12 carbon atoms or alkenyl radical having 2-4 carbon atoms,
X is - halogen,
or a compound of the general formula OC (O) R⁴, where R⁴ is - alkyl radical having 1-6 carbon atoms or aryl radical having 6-12 carbon atoms, and containing as carbonate filler at least one of the compounds of the general formula MxCO₃, where M is - NaH, NHR₄, Na, K, Ca, Mg, Ba, x is 1 or 2, and the component ratio (in mass particles) is as follows:

Organosiloxane rubber: 100
organosilicon crosslinking agent: 5-30
Carbonate filler: 20-120

There are other possibilities, where expediently:

• - The composition additionally 60 to 150 parts of aluminum hydroxide
• - The composition additionally contains 0.01 to 0.5 parts Zinndialkyldikarboxilat according to the general formula: R⁵₂Sn [OC (O) R⁶] ₂, where
  R⁵ - alkyl radical having 2-4 carbon atoms,
  R⁶ is alkyl radical having 8-12 carbon atoms,
• - The composition additionally 0.01 to 0.3 parts of dispersed boron with a specific surface from 3 to 10 m² / g and particle size in the range of 0.2 to 20 μ,
• - Aluminum hydroxide in the composition in powder form with particle size of 0.5 to 10 μ is used
• - Boron as part of at least one compound of the group B₂O₃, H₃BO₃, TiB₂, Si₃B₄, AlB the composition is added.

The foamable organosiloxane composition is prepared in the following manner:
It prepares a mixture of organosiloxane rubber and Karbonatfüllstoff, then added to the mixture a crosslinking agent. Aluminum hydroxide and disperse boron are added to the mixture as needed to corresponding properties of the material to be produced. The additives mentioned are to be added to the mixture before adding the crosslinking agent.

The liquid organosiloxane used in the present invention Rubbers belong to the class of linear and linear-stage polyorganosiloxanes which are used in the Individuals in the Treatment (High Molecular Compounds, Volume XXX, N 9, Moscow, 1988, Pages 1832-1836).

Adding a crosslinking agent to the previously prepared mixture of liquid Organosiloxane gum and carbonate filler causes a component reaction which  the cross-linking of rubber and simultaneous precipitation of HX acid products (Hydrogen chloride or carboxylic acids) according to the scheme ≡ SiOH + XSi ≡ → ≡ SiOSi + HX to Episode has. The HX products excreted by the abundant Bicarbonate filler neutralized while giving the carbon dioxide CO₂ and corresponding Salts off. The excretion of hydrogen and other combustible and explosive gases in the sale of the above-mentioned reactions is basically unthinkable. Since all the above reactions take place at the same time, the leaving one leaves Carbon dioxide will foam the overall composition and the resulting foam will go through Rubber crosslinking with formation of foam elastomers fixed (bound).

To make the foam elastomer unburnable, you can the mixture of liquid Rubbers, carbonate filler and crosslinking agents additionally Antipyrene in the form of add powdery aluminum hydroxide with particle size of 0.5 to 10 μ.

In addition, the antipyrens can still arise as by-products (salts), which usually incurred in the reaction of Karbonatfüllstoffs with HX compounds.

The foamed polyorganosiloxane obtained on the basis of the present invention Compositions are characterized not only by high heat resistance, but also by less gas evolution under irradiation up to 500 Mrad. The resulting solid residue represents a mixture of silicate carbonates of the metals belonging to the composition reserves the original shape and dimensions of a foam elastomer (before irradiation) and see outwardly like a solid volcanic pumice.

Substituting the offered foaming composition for isolation or encapsulation of radioactive substances containing dividing radionuclides (U-235, Pu-239, etc.), you can add to the composition additives that provide for absorption of the neutrons and reduce the multiplication factor of the neutrons to K∞ 0.95, which is a nuclear Safety guaranteed.  

As such additives are boron-containing substances in disperse powder form in question.

The foaming organosiloxane compositions produced by this invention draw characterized by a very high fire resistance. The samples of this material do not burn, if you expose it to the flame of the Bunsen burner, but slowly get to the Mineralize the surface, the mineralization stops when you take the samples from the Flame removed.

According to another process technique, those due to the present invention produced specimens of foam elastomers with combustible solvents (gasoline and Petrol), housed in porcelain bowl and set on fire. Depending on Burning out the solvent can be used on the surface to form a soot layer observe, after a complete burning out of the solvent the flame goes out.

Thanks to the above-mentioned properties, it is possible to obtain, based on the present invention produced foamable organosiloxane compositions as promising materials consider, which can open up for such applications such as production of fire-resistant protective clothing, fire-resistant coatings, lightweight Fire protection partitions for buildings, ships, rooms, fire protection compaction of Breakthroughs after cable and cable laying, etc.

What distinguishes these materials is that in the conversion of the elastomers in solid Foam ceramic in open flame practically no smoke can develop.

A clear picture of the special features and advantages of the present invention can be had only after studying examples of implementation of the invention and test results radioactive flame tests.  

Preparation of the compositions

Per 100 parts by mass of liquid polyorganosiloxane rubbers, which can be used either as individual compounds or as rubber mixtures with the abovementioned values R, R 1, R 2, n, m, l, k, one takes from 20 to 120 parts of carbonate filler. As such, at least one of the compounds of the general formula (M) _x CO₃ is used, where M is - NaH, NH₄, Na, K, Ca, Mg or Ba, and x - 1 or 2. Here, the fillers are added in disperse powder form with particle size of 1 to 10 μ.

In addition, aluminum hydroxide and / or boron-containing substances can be dispersed in the mixture Add powder form.

The prepared mixture is carefully stirred in roller stirrers until a Homogeneous plastic paste with a viscosity of 30 000 to 120 000 Pa · s gets.

To a foamed organosiloxane composition (further as a foam elastomer to produce), takes per 100 parts by mass of rubber - 5 to 30 mass particles Crosslinking agent, either as individual compounds or as a mixture of compounds according to of the general formula R³ SiX₃ with the above R³, X. values.

To influence the speed of the foaming, one can still use the composition 0.01 to 0.5 part of tin dialkyldikarboxylate (eg tin diethyl dikaprilate or tin dibutyl dilaurate) enforce.

15-20 sec. after stirring the paste and the crosslinking agent turns the Foaming of the mass, which from an insignificant self-heating to 35-45 ° C accompanied, whereby the mass reaches a 1.5-10 times the original volume.

The resulting viscous flowable plastic foam loses flowability and surface Tackiness within 2 to 10 min. The vulcanization comes to an end in 20-90 minutes (afterwards  the tightness and elasticity of the foam remain constant). Similarly, the formation of the Foam elastomers on any dry, wet surfaces as well as on water surface and those of the water solutions in front of him.

Examples of preparation of concrete compositions based on the present invention are listed below under numbers 2 to 6. In Example 1, the preparation of the Composition due to a comparable substance (US, 4705810) described.

In Examples 2 to 6, the components are evaluated in mass particles. The viscosity of the Rubber - η is given in mPa · s.

Examples of implementation of the invention example 1

According to the invention - comparable material prepares the composition consisting of Components A, B and C, too.

To prepare component (A), 100 parts by weight of dimetylpolysiloxane having a viscosity of 90,000 mPa.s are used, and the ends are inhibited by dimetylvinylsiloxigruppen (I); These are mixed with 70 mass particles of ground quartz with size of the particles of 5 μ (II) and the mixture is added to the solution H₂PtCl₆H₂O in isopropyl alcohol in the amount which is sufficient for 10 ^-4 parts of Pt per 1 part mixture.

Then component (B) of the composition is prepared by making a mixture 90 parts by mass (I) and 10 parts by mass of the product from the mithydrolysis of 1 minor (C₂H₅O) ₄Si and 2 Moll (CH₃) ₂HSiCl in toluene, then it is washed with water and Subsequently, all volatile products are distilled at a temperature up to 130 ° C. the The resulting mixture is added to 60 parts by mass (II) and left in a mechanical mortar stir until you get a homogeneous paste.  

Component (C) of the composition is prepared as follows: to prepare a mixture of 100 parts by mass of calcium carbonate with size of the particles to 0.5 μ and 80 parts by mass of polydimethylsiloxane, blocked at the ends by means of (CH₃) ₃SiO _0.5 groups , with a viscosity of 100 mPas too.

The mixture is allowed to stir in a mortar until a homogeneous paste is obtained gets, then you put on 60 parts by mass of adipic acid.

Mix the components (A) and (B) in a ratio of 1: 1 and stir thoroughly. Per 100 parts by mass of the mixture is added 6 parts by mass of component (C) and allowed to Continue stirring the mixture in a mechanical mortar. The paste thus produced you put in a tool. Then they are allowed in a thermal cabinet withstand a temperature of 175 ° C for 15 minutes. After foaming and cooling gets a homogeneous elastic foam with a density of 0.6 g / cm³.

Example 2

Due to the present invention, a composition is prepared:

Organosiloxankautschuk -100 (n = 700, k = 1 = 0, n + k + 1 = 700, m = 0, R-CH₃, R¹-C₆H₅, η = 8000) @ Crosslinking agent: -20 C₆H₅SiCl₃ @ Karbonatfüllstoff -50 Na₂CO₃ @ aluminum hydroxide -150 Al (OH) ₃ @ dispersed boron -0.2 B @ Zinndialkyldikarbonat -0.01 (C₂H₅) ₂Sn [OC (O) C₇H₁₅] ₂

The mixture prepared in the above order is poured into the Ftoroplast tool or polyethylene, is allowed to foam and cure for 2 to 5 minutes and a homogeneous elastic foam elastomer arise, which easily after 20 to 90 minutes from the Remove mold. The tightness of the elastomer produced is 0.24 g / cm³.

Similarly, the frothing of the composition occurs for examples 3 through 6.

Example 3

It prepares to a mixture:

Organosiloxankautschuk -100 (n = 10, k = 1 = 0, n + k + 1 = 10, m = 10, R-CH₃, R'-CH₃, R² C₆H₅, η = 7200) @ Crosslinking agent: -20 (Mixture) incl. @ CH₃, Si (CH₃COO) ₃ -5 C₆H₅ SiCl₃ -15 Karbonatfüllstoff -50 (Mixture) incl. @ K₂CO₃ -30 MgCO₃ -20 aluminum hydroxide -100 Al (OH) ₃ @ dispersed boron -0.8 B₂O₃ @ Zinndialkyldikarbonat -0.01 (C₂H₅) ₂Sn [OC (O) C₇H₁₅] ₂

After foaming you get a homogeneous foam Tightness of 0.43 g / cm³  

Example 4

It prepares to a mixture:

Organosiloxane gum η = 4400, incl. -100 a) (n = 100, k = 1 = 50, n + k + l = 200, m = 5, R-CH₃, R¹-CH₃, R² C₆H₅,) -40 b) (n = 300, k = 1 = 50, n + k + 1 = 400, m = 0, R-CH₃, R¹-CH₃, R² C₆H₅,) -40 c) (n = 100, k = 1 = 50, n + k + l = 200, m = 0, R-C₂H₅, R'-CH₃, R² C₆H₅,) -20 Crosslinking agent: -20 CH₃, Si (CH₃COO) ₃ @ Karbonatfüllstoff -90 (Mixture) incl. @ CaCO₃ -60 BaCO₃ -10 K₂CO₃ -20 aluminum hydroxide -60 Al (OH) ₃ @ dispersed boron -1.2 H₃BO₃ @ Zinndialkyldikarbonat -0.5 (C₄H₉) ₂Sn [OC (O) C₁₁H₂₃] ₂

After foaming you get a homogeneous foam Tightness of 0.62 g / cm³

Example 5

It prepares to a mixture:

Organosiloxankautschuk -100 (n = 300, k = 1 = 50, n + k + 1 = 400, m = 0, R-CH₃, R¹-CH₃, η = 1800) @ Crosslinking agent: -16 (Mixture) incl.  @ CH₃, Si (CH₃COO) ₃ -8th C₂H₅, Si (CH₃COO) ₃ -8th Karbonatfüllstoff -120 (NH₄) ₂CO₃ @ Zinndialkyldikarbonat -0.3 (C₂H₅) ₂Sn [OC (O) C₇H₁₅] ₂

After foaming you get a homogeneous foam Tightness of 0.32 g / cm³

Example 6

It prepares to a mixture:

Organosiloxane gum η = 40,000, incl. -100 a) (n = 140, k = 1 = 30, n + k + l = 200, m = 5, R-CH₃, R¹-CH₃, R² C₆H₅,) -50 b) (n = 1100, k = 1 = 50, n + k + 1 = 1200, m = 0, R-CH₃, R¹-CH₃,) -50 Crosslinking agent: -30 (Mixture) incl. @ CH₂ = CH) SiCl₃ -5 CH₃SiCl₃ -25 Karbonatfüllstoff -60 (Mixture) incl. @ Na₂CO₃ -30 NaHCO₃ -30 aluminum hydroxide -80 Al (OH) ₃ @ dispersed boron -0.8 TiB₂

After foaming, a homogeneous foam with a density of 0.51 g / cm³ is obtained  

The results of the irradiation and flame tests, based on the present and foam elastomer produced in accordance with the invention are shown in Table 1 and Table 2 listed.

The tests were carried out with samples in size 50 × 30 × 20 mm.  

Table 1

Results of irradiation

(Box of 2 Mrad / h, integral box 500 Mrad)

Table 2

flame test

As can be seen from the test results, those based on the present invention to be produced foam organosiloxane compositions better radiation resistance in comparison to conventional compositions, form after irradiation a hard solid residue and are practically incombustible. Foaming does not produce hydrogen.

It is also apparent from the tests that when foaming a catalyzed composition on dry metal, glass, concrete, many plastics, organic and silicone rubber excel the foam elastomers produced by the present invention are the usual ones Strength parameters. When applying the composition to water or aqueous Solutions a whole porous film is formed on the surface.

Industrial applicability

This invention can find the best application in the manufacture of materials which among others in the aviation industry as refractory, non-toxic fillings for Clearances, hermetic windows, electrical installations, floors as well as Fire protection coatings for walls without the use of combustible adhesives and heat and heat sound insulating materials are used. Furthermore, according to this Invention materials also for the separation of the radionuclides serve contaminated objects from the environment.

Claims (6)

1. The foamable organosiloxane composition containing the liquid organosiloxane rubber, the organosilicon crosslinking agent and the Karbonatfüllung is characterized in that there are included as follows: as an organosiloxane rubber: the rubber or a mixture of rubbers with the general formula as follows: Where:
R, R¹, R ² - the lowest alkyl radical having 1 to 6 carbon atoms or an aryl radical having 6 to 10 carbon atoms and
n - an integer from 10 to 1500 and
k, l - integers from 0 to 500;
(n + k + l) - an integer from 10 to 1500 as well
m is an integer from 0 to 10;
as the organosilicon crosslinking agent: a compound having the general formula as follows:
R³SiX₃ or mixtures thereof where:
R³- is an alkyl radical having 1 to 6 carbon atoms or an alkenyl radical having 2 to 4 carbon atoms,
X - a halogen or a compound having the general formula OC (O) R⁴ where:
R⁴ is an alkyl radical of 1 to 6 carbon atoms or an aryl radical of 6 to 12 carbon atoms;
as carbonate filling: at least one of the compounds having the general formula as follows:
MxCO₃ where:
M - NaH, NH₄, Na, Ca, Mg, Ba as well
x - 1 or 2;
this is the case for the following ratio of components (in mass proportions):
Organosiloxane rubber - 100
Organosilicon Crosslinking Agent - 5-30
Carbonate filling - 20-120. 2. The composition for Pt. 1, which is characterized in that it additionally 60 contains up to 150 parts by weight of aluminum trihydroxide. 3. The composition to Pt. 1, which is characterized in that there is additionally 0.01 to 0.5 part by mass of tin dialkyldikarboxylate with the general formula R⁵₂Sn [OC (O) R⁶] ₂, where:
R ⁵ - alkyl radical having 2 to 4 carbon atoms and
R ^{6 are} alkyl radicals having 8 to 12 carbon atoms,
are included. 4. Composition to the Pt. 1, which is characterized in that it additionally 0.01 to  0.3 mass fraction of dispersed boron with a specific surface of 3 to 10 m² / g and sizes of the particles from 0.2 to 20 microns. 5. The composition for Pt. 2, which is characterized in that the Aluminum trihydroxide in the powder form with sizes of the particles in a range between 0.5 and 10 microns is used. 6. The composition for Pt. 1, which is characterized in that it is 0.01 to 0.3 Mass fraction of the at least one compound from the group: B₂O₃, H₃BO₃, TiB₂, Si₃B₄, AlB contains.