The value of silicone liquids in the Big Soviet Encyclopedia, BSE. COLOSHOGANICAL LIQUID SILONSORGANIC LIQUID

Liquid is a strong weakness from fluid loss - psorinum. Creation of liquid, fear of water - an alconium. The angry fluid is not accepted by the stomach, but spew the vomit, cold is accepted -

In the middle of the last century, extensive research began on oil development and lubricants using silicone liquids - oligorganosyloxanes. Oligoorganosiloxanes are an extensive group of highly efficient oligomeric substances with a complex of properties inherent in this class of polymeric compounds and not repeated in any of the other natural or synthetic materials currently known.

There are oligorganosiloxanes of linear, cyclic and branched structure.

The most widely used oligodorganosyloxanes of the linear and branched structure characterizes the high flexibility of chains and freedom of rotation of organic groups around the Si-C and Si - O bonds that determine the high mobility and a minimum of free energy in molecular chains.

The features of the structure of oligodorganosyloxanes lead to the low dependence of their viscosity and other properties of temperature, to low glass transition temperatures and melting (from minus 60 to minus 130 ° C) and at the same time high heat resistance (200 - 420 o C), which determines the preservation of operational properties in a wide The temperature range of oils and lubricants based on them. The features of the properties of oligodorganosyloxanes are common for all types of oligomers and manifest themselves during their operation.

For silicone liquids there is no alternative where it takes extremely high or low temperature, the protection of the material in hard conditions friction, even in the conditions of radiation.

It is known that the properties of oligodorganosyloxanes can be significantly changed, in the structure of elements of asymmetry, rigidity, polyanya, etc., thereby changing and temperature limits of operation of oligorganosloxanes, in particular, when using them as the bases of oils and lubricants.

Depending on the composition and structure of oligorganosiloxanes are mixed in any ratios with many organic media, or do not mix at all. Depending on the composition and structure of oligorganosiloxanes, there is a good lubrication for various friction pairs or do not possess lubricating properties at all.

In the working conditions, the service life of oils and lubricants to a large extent depends on thermo-oxidative stability and evaporation of the base, i.e. The dispersion medium, which uses oligorganosiloxanes. Thus, comparing oligorganosiloxanes of various structures are visible (Table 1), that they differ significantly in terms of "weight loss%" at temperatures of 200 and 250 o C, as well as on the temperature of the start decomposition in vacuo: from 272 o C for polyethylsiloxane and up to 362 O C for polymethylphenylsiloxane.

Table 1.

One of the most important properties of oligodorganosiloxanes is the temperature of frozen, or fluidity loss. Low sprouting temperature ensure the preservation of oil and lubricants based on them at low negative temperatures. Table 2 shows the oligomers of the asymmetric structure, their fluidity loss temperatures and viscosity values \u200b\u200bfor minus 50 ° C

Table 2.

Thus, according to foreign and domestic researchers, the dignity of materials based on oligorganosiloxanes is their high thermo-, frost, water resistance, as well as physiological inertia and environmental safety.

An important property of Olgorganosiloxanes is also their complete corrosion inertness.

The GNIIHTEOS developed a wide range of oligorganosyloxanes, whose properties depend on the structure of the polymer framework and on the nature of the organic substituents framing the siloxane chain, as well as the nature of the terminal groups. As a result fundamental studies Oligorganosiloxanes are developed containing methyl, ethyl, phenyl substituents at the silicon atom, as well as containing substituents with a halogen in an organic substituent, heterocyclic links and others. The oligorganosiloxanes of the linear structure can be represented as a general formula:

R 1 R 2 R 3 Si N O Si R 1 R 2 R 3,

Where: R 1 \u003d - CH 3, - CH 2 CH 3, - C 6 H 5, -CH 2 CH 2 CF 3

R 2 \u003d - CH 3, - CH 2 CH 3, - C 6 H 5, -CH 2 CH 2 CF 3

R 3 \u003d - CH 3, - CH 2 CH 3, - C 6 H 5, -CH 2 CH 2 CF 3

R 4 \u003d - CH 3, - CH 2 CH 3, - C 6 H 5, -CH 2 CH 2 CF 3, - C 6 H 3 Cl 2 and others

R 5 \u003d - CH 3, - CH 2 CH 3, - C 6 H 5, -CH 2 CH 2 CF 3, - C 6 H 3 Cl 2 and others,

with different combinations,

n \u003d from 1 to several thousand

The range of developed oligorganosiloxanes includes several hundred items, each of which has only inherent properties.

I propose to consider some types of oligorganosiloxanes more carefully.

1. Oligorganosyloxanes containing methyl substituents in silicon atoms in the siloxane chain are the most common and accessible are the most common and affordable. IN general The oligodimethylsiloxanes of the linear structure can be represented as a general formula:

(CH 3) 3 SI N O Si (CH 3) 3

They are called oligodimethylsiloxanes, or PMS liquids. PMS liquids under various names produce all the leading firms specializing in the production of silicon-organic products.

In our country, oligodimethylsiloxanes were developed with a linear structure of molecules having an industrial brand "PMS" and the branched structure of molecules - the industrial brand "PMS-P". Both types have a wide range of properties depending on the composition, structure and molecular weight. The main indicator for the areas of their use is kinematic viscosity, the value of which determines the brand of liquids.

PMS-P is distinguished by a wider range of operating temperatures up to minus 130 o C in comparison with minus 65 o C for linear PMS.

Due to the fact that PMS liquids have low lubricating properties under friction steel steel, their use in the compositions of oils and lubricants is limited. However, some combinations of rubbing pairs, for example, bronze steel, brass-plastic, with hydrodynamic lubrication, PMS liquids work satisfactorily.

The use of PMS liquids in the compositions of oils as anti-bellged additives due to their low surface tension values \u200b\u200b(from 18 to 20 N / m).

The use of PMS liquids as liquid media in oils and lubricants compounded by various anti-wear additives and dispersion creates favorable conditions for selective adsorption of additives on the friction surface and for the formation of an anti-wear film, which allows to significantly increase the pressure and sliding speeds.

An examples of PMS-20R, PMS-100R, PMS-117R, used as the basis of special low-temperature oils and lubricants with a temperature of frozen no higher minus 100 o C.

Effectively use of PMS liquids as components in pastes and vaselines. The staff of the GNIIHTEOS developed an assortment of petroleum and pastes (about 10 different brands).

Together with Soyuzengogaz NGO employees, options for sealing pastes based on highly viscous polymethylsiloxanes and PMS average viscosity for sealing ball valve shut-off valve valves of gas highways

High dielectric properties and their low temperature dependence on temperature assume the efficiency of using PMS liquids as transformer oils. If we consider that oligodimethylsiloxanes do not form conductive products during electrical sample or sparking, then their indispensability is becoming understandable when used in transformers. Today the Institute has the necessary scientific potential to restore and continue research on the development of transformer oils to create industrial production.

Oligodiethylsiloxanes (PES-liquid) They differ from other types of silicon-organic liquids primarily good compatibility with organic media, as well as lower pouring and glass transition temperatures. In addition, oligodiethylsiloxanes have higher lubricant properties compared to PMS liquids, which determined their widespread use as the basis of oils and lubricants

Table 3 presents the temperature and operational properties of the most famous currently known oligoethylsiloxanes

Table 3.

Temperature and operational properties of some

oligodiethylsiloxanes

Due to the characteristic only for them, the property is combined with organic compounds and mineral oils, developed and produced a large range of oils and lubricants, which maintain operational characteristics at high (up to 150 ° C, briefly up to 200 ° C) and low (up to minus 100 o C) temperatures , distinguished by increased water resistance, high pressures. It should be noted that the use of PES liquids in the compositions of oils and lubricants made it possible to solve a number of unique tasks that could not be solved using oil and organic oils.

On the basis of oligodiethylsiloxanes, widespread lubricants are created by CITIM, VNIIIIP of various brands. When using mixtures of oligodiethylsiloxanes and mineral oils, instrument low-temperature oils of grades 132-07, -08, -19, -21, -21, instrument lubricants of the OKB, frost-resistant greases Severur-1, unison 3m are created.

As noted earlier, a distinctive feature Oligodiethylsiloxanes is full compatibility with mineral oils. Additives of PES-liquids to hydrocarbons improve low-temperature characteristics of the latter. The table shows the data of the viscosity characteristics of the Mixes of the PES-4 liquid and mineral oil during their various ratios.

Table 4.

The viscosity characteristics of PES-4, mineral oils and their mixtures

These data confirm that the addition of PES-liquids to hydrocarbons improves the low-temperature characteristics of the latter.

It should be noted that a significant impact of fluid behavior at high pressures has a significant impact on the work of lubricants. Lubricants with increasing pressure increase their viscosity and eventually harden. Studies of changes in viscosity with an increase in pressure at different temperatures have shown that oligodiethylsiloxanes are characterized by the smallest change in viscosity.

Currently, of all other types of oligorganosiloxanes, only PES liquids are produced in our country on an industrial scale. Moreover, Russia is the only manufacturer of PES-liquids in the Axortiment.

2. Oligomethylphenylsiloxanes (PFMS-liquid) represent the compounds of the general formula:

(R) 3 Si N O Si (R) 3

(R) 3 Si \u003d (CH 3) 3 Si -, (CH 3) 2 (C 6 H 5) Si -, (CH 3) (C 6 H 5) 2 Si -, (C 6 H 5) 3 Si -

Oligomethylphenylsiloxane molecules chains may consist of methylphenylsiloxy-links, or from dimethyl and methylphenylsiloxy-links.

The introduction of phenyl substituents into the composition of oligodorganosiloxane significantly increases the level of intermolecular interaction due to an increase in the rigidity of the chains of molecules, limiting the freedom of rotation of atoms and groups of atoms around the bonds Si-O and Si-C, as well as due to the appearance of specific intermolecular interactions due to the presence of the considered oligomers Aromatic nuclei. As a result, the physical properties of oligomers change. Increasing viscosity and density, for example, in the first approximation, it is symbolically with an increase in the number of phenyl substituents in the oligomethylphenylsiloxane molecule.

This type of liquids differs from the much higher heat resistance described above and thermo-oxidative stability, which determines the specific areas of their use. Three main directions of use of oligorganosyloxanes containing methyl and phenyl substituents are known: high-vacuum oils; coolants for high and low temperatures; Dispersion media for heat-resistant oils and lubricants.

For oligomethylphenylsiloxanes, a combination of increased heat resistance, low glass transition temperatures, low vapor pressure, compatibility with organic media are characterized. The following are some areas of application of a number of PFMS-liquids:

PFMS-2,5l, FM-1, FM-2, PFMS-13, etc. are used in diffusion vacuum pumps with a limit vacuum from 133,322npa to 13.332 MCP

FM-5, FM-6, FM-5,6AAP is used as dispersion media low-temperature oils and lubricants, in low-loaded high-speed ball bearings and freon refrigeration machines.

133-79, 133-158, copolymer 5 and copolymer 3 are used as heat-resistant and low-temperature media in oils and lubricants operable in a wide range of temperatures and in deep vacuum.

The areas of using oligomethylphenylsiloxanes to obtain consistant lubricants covers both heat-resistant lubricants, vacuum antifriction and special instrumentation, electrocontact, sealing and nontasted lubricants.

Among foreign manufacturers of PFMS liquids such large players like "Dow Corning" (USA), "Wacker" (Germany), "Shin Etsu" and "Toshiba" (Japan). In most cases, products manufactured by listed firms are analogues developed by our scientists of PFMS-liquids. The PFMS-liquid produced abroad is included in the compositions of oils and lubricants produced by firms themselves, for example, a large number of lubricants of the Molycotom group.

In our country, despite the developed large assortment of PFMS-liquids, there is no industrial production. Back in the 1990s, due to the reduction in the need for oligorganosiloxanes, the industrial release of PFMS-liquids was minimized, despite the undoubted success of our specialists who had already had almost analogs of all foreign materials of this type (Table5).

A sharp decrease in the need for oligorganosiloxanes, in particular, in the PFMS-liquids, in the 1990s led to the termination of their release. At the same time, the development of oligorganosiloxanes and an assortment of oils and lubricants based on them is developed abroad. Thus, the company "Dow Corning" (USA) has developed an assortment of PFMS-fluids DC-550, DC-510/50, / 100, / 500, / 1000, DC-710, and others used by the firm as the basis of oils and lubricants in The temperature range from minus 75 to plus 232 o S. In our country, there are developed analogues of foreign oligomers. Table 5 presents comparative data of some oligomethylphenylsiloxanes produced by "Dow Corning" and developed in our country.

Table 5.

Comparative data of oligomethylphenylsiloxanes manufactured by "Dow Corning" (USA) of Russia's developments

The group developed and currently halogen-containing oligorganosiloxanes include oligodorganosiloxanes, having chlorine atoms (dichlorophenyl substituents) and fluorine (γ-trifluoropropyl substituents) in the composition of molecules (γ-trifluoropropyl substituents).

Oligoorganosiloxanes containing a halogen in an organic substituent have a unique complex of properties. They are more polar compared to oligorganosiloxanes of other types, have an improved lubricating ability and limited flammability. The presence of halogen in an organic substituent, in addition to improving the lubricating properties of fluids, changes all other indicators: viscosity, refractive index, frosted temperature and others.

By nature, the developed oligomethyl (halogenorgano) of siloxanes are complex mixtures of molecules that differ in each other as a degree of polymerization and composition.

The GNIIHTEOS developed and implemented in the production of three types of siloxane fluids with halogen in organic substituents:

A) oligorganosiloxanes containing dimethyl and dichlorophenylsiloxy-links (liquids 162-70, 162-170VV, 162-389 and others) have high physicochemical properties: high lubricating ability, low sprouting temperatures (up to minus 90 o C), low viscosity dependence on temperature, increased radiation resistance. They found wide use as the basis for dash oil and lubricants. In particular, the liquid 162-170VB is used as the basis of dash oils, plastic lubricants operating under conditions of deep vacuum and vibrating loads of microelectrodic motors with low tension of the touch.

B) oligorganosiloxanes containing γ-trifluoropropyl substituents. (FS liquids). A range of FS fluids was developed with a range of viscosity values \u200b\u200bfrom 20 to 1200 WST at 20 ° C. Different brands of fluorine-containing oligorganosyloxanes are used as the main component of motor oils, working fluids for lubricating microcryogenic compressors, in hydraulic systems of pumping units, liquid lubricants for depths hourly mechanisms, the basics of dashboard and plastic lubricants used in extreme conditions at temperatures up to 300 o

C) oligorganosiloxanes containing both dichlorophenyl and γ-trifluoropropyl substituents at the silicon atom (FCS liquid) are functional at temperatures up to 250 ° C in hydraulic systems, hydraulic surfactants and other systems with stained steel hubs, providing in these conditions increased lubricant and stable characteristics. In the complex of properties that determine the practical value of oligorganosiloxanes, one of the most important characteristics are antifriction, anti-mailing and anti-wear properties. The study of the lubricating properties of FCS fluids has shown that the simultaneous presence of dichlorophenyl and γ-trifluoropropyl substituents in the oligomer gives the effect of synergies under boundary friction. FCS fluids have the best lubricating properties compared with liquids containing only dichlorophenyl, or γ-trifluoropal substituents at the silicon atom. The most studied representative of this type of oligodorganosiloxanes is liquid 169-36, which is a heat-resistant fluid with a high lubricity, with reduced flammability, which is the basis of lubricants, and is also designed to work in the shock absorbers of various types (blade, telescopic) for the heavily loaded widespread equipment.

Other types of oligorganosyloxanes containing organic substituents such as teyenyl, β-cyanoethyl, β-adamanthyterletyl, pentrenyl, and others have been developed and studied in the GNIIIFTEOS. Developed oligorganosiloxanes represent, undoubtedly, great practical interest, however, due to the shortage of raw materials, they are currently little accessible.

Currently, GNIIHTEOS holds a wide range of works on the creation of oligorganosiloxanes - the foundations of oils and lubricants with higher consumer properties, which are oligomers with mixed substituents, volume substituents, and also improves the technology of obtaining oligoorganosyloxanes in order to improve the quality and stabilization of their properties.

The studies conducted in recent years allowed us to obtain oligorganosiloxanes with high lubricant properties (the diameter of the wear spots on a four-sick friction machine is less than 0.42 mm at a temperature of 20 ° C, 1450 rpm, 196 N, 60 min, "Steel-Steel"), With a low viscosity dependence on temperature and low sprouting temperatures (up to minus 120 o C).

Analysis of the use of oligodorganosiloxanes as a dispersion medium in the production of lubricants of various purposes in our country showed that from the entire variety of lubricants only just over 20 items are based on the use of silicon-organic fluids. At the same time, the range of manufactured, for example, only the company "Dow Corning" (USA), a silicone-based lubricant includes more than 50 items.

It should be noted that the creation of oils and lubricants workable in extreme conditions (high and low temperatures, high values \u200b\u200bof the scale of the capepulation, high pressure, resistance to emission action different types) It is impossible without using oligorganosiloxanes.

In our opinion, intensive research in the field of synthesis and production technology of oligorganosyloxanes, carried out in Russia and, specifically, in the GNIIHTEOS, efforts to introduce new materials to various industries, work on the creation of a new large-capacity complex for the production of silicon-organized materials will allow change in the coming years This situation.

Creamy liquid

Polymethylsiloxa new liquids (PMS) Represent polymers of the linear and branched structure of the general formula:

(CH 3) 3 SiO N Si (CH 3) 3

They differ from other silicone polymers with a more common temperature viscosity curve. The viscosity of PMS, depending on their molecular weight, can vary from 1.5 to 1. 10 6 CST. Excellent superficial acting properties of PMS make it possible to widely use them as a surfactant and anti-inflexible additives, anti-adhesives, the basics of lubricants, coolants, etc .. In addition, they are corrosion-resistant and have high dielectric indicators.

The main properties of the polymethylsilox of new liquids and their applications

Polymethylphenylsi Locane fluids represent linear oligomers of the general formula:

R [m 2 sio] n sio [MFSIO] M SIR, where R \u003d (CH 3) 3 or CH 3 (C 6 H 5) 2, M \u003d CH 3, F \u003d C 6 H 5

Polymethylphenylsi Locane (PFMS) liquids have increased heat resistance, low pressure of dried vapors, low evaporation and high flare point values. The limits of permissible temperatures of the operation of these liquids depending on the composition ranges from -60 to +250 ° C (long) and up to +350 ° C (briefly).

The main properties of the PFMS and their applications are shown in the table.

Notes:

The refractive index N d 20 for all fluids varies from 1.451 to 1,1,58.

The coefficient of thermal conductivity at 20 ° C for PFMS - from 0.135 to 0.149 W / (m. K).

The average heat capacity of the PFMS of liquids at 30-100 ° C lies in the interval of 1.57 - 1.918 kJ / (kg. K).

Dielectric properties at 20 ° C:

 v, Ohm. cm 10 12 - 10 14

 at 10 3 Hz 2.7 - 3.0

tG . 10 4 at 10 3 Hz 1 - 7

Polyethylsiloxane Very liquid

The polyethylsiloxano of the liquid is mixtures of oligomers in the main linear structure of the general formula:

Specific features of polyethylsiloxane of ochy liquids are their good compatibility with mineral and synthetic oils, good lubricating properties, low frosted temperature (below -70 0 C) and inertia with respect to most structural materials.

Polyethylsiloxane Very liquids are colorless, odorless, chemically inert. They are soluble in aromatic and chlorinated hydrocarbons, insoluble in lower alcohols and water.

Polyethylsiloxane Ovy liquids are non-toxic, explosion-proof.

Currently, polyethylsiloxane is produced by stamps: PES-2, PES-3, PES-4, PES-5, liquid No. 7, 132-24, 132-25, 132-316.

The main properties of polyethylsiloxane of oh fluids (GOST13004-77)

Areas of use

PES-3 PES-3 polyethylsiloxane, PES-4 are used in hydraulic systems (cooling and working fluids), in devices (lubricating oils), and also serve as the basis of low-temperature oils.

These liquids ensure stable operation of the instruments and mechanisms in the conditions of the Far North. The good dielectric properties of polyethylsiloxane oh allow them to use them as working fluids in electromechanism x. Applied at the operating temperature from minus 70 to 150 0 C.

The largest interest is the PES-5 liquid, which has a combination of properties such as high flare point, low frosted temperature, wide range of viscosity change, good lubrication.

Widely applied in various industries:

In the chemical and petrochemical industry:

The main component of the spinning composition used in the production of cord fabric for the tire industry. Strengthens fiber, improves the quality of tire products,

Anti-adhesive lubricant and modifier in the production of press materials, plastics fiberglass,

Antique additive in the production of dyes.

Coolant operating at 150-200 0 C in open systems and at 180-250 0 C in closed,

The basis of anti-adhesive emulsions in the factories of rubber-use products,

Plasticizer in the production of rubber products,

The basis of consistency lubricants of widespread

In perfumery industry:

The base of creams, additive to lipstick and mascaras for eyelashes,

The basis is anti-inflammatory oils for animal husbandry,

In the aviation and automotive industry:

Dempulating liquid, liquid lubricant, primary liquid base, coolant.

The liquid 132-24 is used as a liquid lubricant of the rubbing surfaces of metal-metal and metal rubber and as the basis of consistent lubricants of a wide purpose, including for aviation.

Polyorganosilox Anov liquid dielectrics.

Polyorganosilox Annovy Dielectric Liquids ((PES - D) 132-12D GOST 10916-74; PES - 3D TU6-02-688-76; (Siltan) 136-163 TU6-02-697-76) Their dielectric characteristics are little dependent on the frequency Current and temperature.

The main properties of polyorganosilox of anan dielectrics are shown in the table:

Used to impregnate capacitors and filling the piezodators.

Polymethyl ethylsyl Oksana fluids

Fluids 132-234 (TU 6-02-1-041-92) and 132-244 (TU 6-02-1-019-90) are polydisperse mixtures of polyethylmethylsyl oxane oligomers with a boiling point above 250 o C and differ in various ratios methyl and ethyl substituents and viscosity change ranges ..

The main properties of methyl ethylsilox new liquids

Methyl ethylsiloxy New fluids combine positive properties of both methylsiloxane X and ethyl oxyoxane fluids. They are well combined with mineral oils and synthetic hydrocarbons, non-toxic, corrosion-resistance and, have a low frosted temperature below minus 100 0 C. Due to its special composition of methyl ethylsilox, new fluids are characterized by improved operational and properties and are a good basis for low-temperature lubricants with a small point of stroke negative temperatures and efficient temperatures from -100 to +200 o C and in deep vacuum.

In addition to the direct purpose of methyl ethylsilox, new liquids can be used as: hydraulic liquids for hydraulic drivers, hydraulic drivers, hydrotorts and control systems in various climatic conditions, compressor oil of domestic refrigeration installations, coolants and refrigerants.

Polyorganosilox Anovy liquids with a polar group in an organic substituent.

General formula of fluorosiloxane fluids:

General formula of chlorsiloxane fluids:

General formula Fluorochlorsiloxane of oh fluids:

These liquids are oligomers containing halogen (chlorine or fluorine) in an organic substituent. Depending on the structure and content of polar groups, the properties of oligomers vary widely.

These polyorganosyloxox are colorless transparent liquids insoluble in water, but soluble in ketones, in aromatic and chlorinated hydrocarbons; Do not cause corrosion of metals (steel, aluminum, bronze, etc.) in a wide range of temperatures. The limits of permissible operating temperatures are determined by the composition of the liquid and range from minus 100 to plus 200-300 ° C with long-term operation and up to 350 o with briefly.

Halogen-containing liquids have improved lubricating properties compared with polymethyl and polymethylphenylsi lockers, high resistance to the effect of ionizing radiation.

The main properties of polyorganosyloxoks of the anov liquids with a polar group in an organic substituent are shown in the table:

Liquid 161-44:

The main component of High-temperature oil W-301 is used as a working fluid in rocket-building, as the basis of the working fluid for lubricating compressors with an internal heat sink for microcryogenic systems.

Fluids 161-45 and 161-178:

Working fluids with increased lubricating capacity to work in hydraulic drive systems of high-speed electric pump units, liquid lubricants for depth watch mechanisms, etc. Instruments of increased reliability

Liquid 161-52VV:

Liquid lubricant and base for instrumental oils and plastic lubricants operating under deep vacuum conditions. The basis of effective defoamers for organic media.

Liquid 162-70:

The basis of diet oils, working fluid for testing and testing of high-temperature aggregates and hydraulic systems with a working interval of temperatures from minus 60 ° C to plus 200 o with a long, at 250 o with briefly.

Liquid 162-70VV:

Instrument oil, the basis of plastic and consistant lubricants operating under conditions of deep vacuum and with a small point of stroking.

Fluids 169-36 and 169-389:

Heat resistant, with high lubricant, with reduced flammability, working fluids in shock absorbers of various types (telescopic, padded) for ground heavy loaded transport equipment.

Examples of silicone liquids.

1. Working fluids for vacuum pumps - Liquid brands of PFMS-2 / 5L, FM-1, 119-229

2. High temperature coolants - PFMS-4

3. Low-temperature coolants - PMS-1,5p

4. Swimming materials in the microsurgery of the eye - Substance "Light Silicone" and "Heavy Silicone".

Among the polymethylsiloxes, OligomethylSilox An in the form of a "light silicone" substance, used as a component of operations carried out in the microsurgery of the eye about the severe forms of detachment of the mesh shell, complicated by injuries or diseases of the eye and previously related to inoperable cases. For such eyes, it is characterized by severe condition - coarse destruction of the vitreous body, degenerative change in the retina, clouding of the lens, etc.

Properties of Substance "Light Silicone":

Viscosity at 20 ° C, mm 2 / s I type 1000 - 1500

II type 2500 - 4500

Density at 20 ° C, g / cm 3 0.97 - 0,985

Volatility,% of mass.< 0,1

< 2,1

pH of water title 6 - 7

The indicators of the drug fully correspond to the foreign analogue of the production of the company "Adatomed".

The "light silicone" in the treatment process is always located in the upper part of the eyeball, which allows it to use it with the upper bursts and the tips of the mesh shell, as well as changes on the periphery of the eye bottom.

Based on the copolymer of polydimethylsilok Sana and methyl--trifluoropropilsi Locksan of the linear structure, a variant of the substance "Heavy Silicone" was obtained. His properties:

Viscosity at 20 ° C, SPZ 1000 - 4500

Density at 20 ° C, g / cm 3 1.06 - 1.08

Volatility,% of mass.< 0,1

Polydispersity, m w / m n< 2,1

The Substance "Heavy Silicone" is used with a positive result in the treatment of eyes complicated by injuries and diabetic retinopathy.

5. Plenochiters. Silonyorganic liquid defoamers are effective in significantly lower concentrations compared to organic defoamers. They have an increased heat resistance, chemically inert to most substances, practically non-volatile and can be used to clean the foam in aqueous and non-aqueous media with different pH values \u200b\u200b- in distillation processes, vacuum distillation, evaporation, etc. The consumption of these defoamers ranges from 0.001 to 1 g. / l. COLOSHORGANICICAL PLAY FIGHTERS FROM APPLICATION IN THE CHEMICAL, PETROCHEMICAL, OIL ORDER COOLING, CULLULAR ORDER, TEXTILE, PHARMACEUTICAL INDUSTRY.

The basic properties of liquid silicone centers are presented in the table.

6. Cooling fluid for transformers. The liquid 131-434 is designed for use as a cooling and operating fluid in power fireproof transformers. Withstands the breakdown voltage at a frequency of 50 Hz not lower than 50 kV / mm.

Composite materials based on silicone liquids

Silicone fluids for nuclear power plant The compositions of oligorganosipers of Sanov with stamps additives: 131-209, 133-257

Successfully used in the hydraulic armor of the AH of nuclear power plants, especially in seismic frequencies with a load from 50 to 170 tons, as well as at an increased load of 170 to 450 tons at domestic nuclear power plants and stations of neighboring countries since 1985 (Balakovo NPP, Rostov NPP, Kalinin NPP , Rivne NPP, Armenian NPP). The fluids have unique properties and are successfully operated within 8 - 10 years without replacement.

Anti-adhesive curable compounds - Compositions based on oligorganosipers of sanitary liquids.

Anti-adhesive compositions of "hot" (CX-5, 131-458, and "cold" (SK-223) curing are designed to process metal molds used in molding composite polymeric materials - fiberglass, carbon fiber, boroplastics on epoxy binder, rigid polyurethane foam , LVL polymethyl methacry. After curing, solid transparent coatings are formed on the surface of the form surface, which has anti-adhesion properties relative to the material formula.

Used when forming products of aviation, sports and therapeutic (lenses) of destination.

Lubricating compositions C-211 and C-236 , efficient temperatures from minus 60 0 s to plus 200 0 C, designed to protect the hydraulic system of aircraft from the leaks of the working environment (chassis, flaps, etc.) in order to ensure the normal operation of external equipment, devices. It is allowed to use these lubricants in vacuum installations, gyroscope bearings, in the nodes of friction of ground mechanisms operating in vacuum, as well as as a buffer medium for glass optical movable contacts.

Emulsions

Polyorganosilox Annovy liquids form stable oil emulsions in water, which are a white sour creamy mass. The aqueous emulsions of silicone fluids are produced 50-70% wt. Concentration and applied in a diluted form. The initial emulsion is mixed with water in any ratios, dilution stability is more than 24 hours.

The main properties and scope of emulsions are shown in the table.

Oils and lubricants

Plastic lubricant cyatim-221- based on polyethylsiloxane fluid. The temperature range of operation from -60 to +150 ° C (briefly up to +180 ° C). Lubricant insoluble in water, chemically rack and inert with respect to tires and others polymeric materials. The lubricant has proven itself in rolling bearings, and is also widely used in rubber-metal rubber steam for lubricating pneumatic cylinder seals. It is widely used in aggregate bearings of aircraft of various types. Lubrication is successfully used in aircraft bearings, instrument bearings and low-loaded gearboxes. As the instrument lubricant can be used at atmospheric pressure and in vacuo.

Plastic grease OKB-122-7 - Based on polyethylsiloxane fluid, the temperature range of application from -60 to +120 o C. Lubrication is characterized by high water resistance, colloidal and chemical stability, as well as good protective properties. The lubricant was widespread as a multipurpose dashboard for aviation and other electromasic, accurate mechanisms, precision bearings, etc.

Oils 132-08, 132-20 -based on the polyethylsiloxane composition with mineral oils. Used as low-temperature dash oils.

Silicone fluids (silicone liquids, silicone oils) - oligorganosiloxanes that do not contain functional groups for subsequent polymerization, with closed terminal non-reactive links. There are liquids with different viscosity, the temperature of frozen and glass transition, heat resistance and other properties.

Properties of silicone fluids

Silicone fluids are an extensive group of highly efficient oligomeric substances with a complex of properties inherent only to this class of polymeric compounds, and not repeated in any of the currently known natural or synthetic materials.

They have low glass transition temperatures and yield loss (-60 ° C ... -130 ° C) and at the same time high heat resistance (200 ° C ... 350 ° C), low pressure of saturated vapor and small volatility, low dependence of viscosity, dielectric and other properties from Temperatures, significant compressibility and high solidification pressure, low surface tension (18-26 MN / M) and high mobility, high hydrophobicity and liofilicity, low viscosity dependence on the shift rate while maintaining a wide range of Newtonian flow during viscosity up to 1500 mm2 / s. For some liquid siloxanes, a significant increase in the parameters of the thermophysical properties (heat capacity and thermal conductivity) in critical and prudicular areas of pressure and temperature are characterized.

Depending on the composition and structure, silicone fluids are mixed in any ratios with many organic media are either completely not mixed.

Radiation resistance of liquid siloxanes also depends on the composition and structure of molecules. They can exhibit high resistance (up to 2 mrad), or they are stitched with the formation of the gel at a dose (1.5 - 3) × 104 is glad.

Depending on the composition and structure of molecules, silicone fluids exhibit a good lubricating ability for various friction pairs or do not possess lubricant properties at all. The composition and structure of oligomer molecules on the rheological properties of liquids in a wide range of temperatures are particularly significantly influenced. For some structures, an abnormally low dependence of viscosity from molecular weight is observed, which is important for all kinds of damping devices.

The structure of organic radicals framed by a siloxane chain structure, the structure of the silicone frame, as well as the presence and nature of the terminal groups in molecules, determine the mechanism and temperature of the thermal and thermo-acid destruction of siloxanes, which ultimately causes the permissible temperature limits of the operation of oligomers. Inertia or reactivity also depend on the structure and composition of the liquid. However, not containing functional groups oligomers are completely inert and do not cause corrosion of the overwhelming number of metals and alloys. They are non-aggressive and in relation to living organisms.

The structure of oligomers depending on the method and conditions of synthesis can be different: oligomers of a linear or branched structure, cyclic or cycline, or combinations of those and others. They may have a significant or small polydispersity on the molecular mass composition of the mixture of oligomologomologists.

Scope of silicone liquids

The noted features of the properties of silicone liquids determine the areas of possible use of these compounds. The first and basic properties are the liquid state in a wide range of temperatures - they determined the circle of their use as a liquid working media for various devices and mechanisms, dispersion media for lubricating oils and lubricants, vaselines and pastes, coolants. High dielectric properties and low temperature dependence on temperature determined the use of silicone fluids as liquid dielectrics in devices, transformer and condensate construction, and the combination of these properties with hydrophobicity - in radio electronics devices. Low glass transition and frost temperatures in combination with heat resistance allowed us to successfully apply them in space technology, aircraft construction, instrument making; Low surface tension - as separation liquids and anti-livensors.

The structure of silicone liquids

Liquid polysiloxanes can be:

Their properties are significantly different. Linear molecules can be folded into the spiral. They are characterized by high flexibility and freedom of rotation of groups around Si-C and Si-O bonds, have little limited mobility and minimum free energy. The features of the structure of linear oligomers lead to the low dependence of their viscosity and other properties on temperature, to low temperatures of glassization and melting, low cohesion energy and viscous flow. They have elastic compressibility.

Oligomers with a cyclic structure of molecules have in varying degrees deformed from the planar structure, and the voltage of valence angles of siloxane communication. Their free energy and entropy differ accordingly from oligomers with linear molecules. The flow of such structures is inhibited, which is manifested in greater dependence of viscosity on temperature. Cyclosyloxanes are easier to form crystal structures, have a greater density and refractive index, are less prone to supercooling and relatively rapidly are rearranged by siloxane bonds into a larger voltage molecule with less voltage in the cycle, which is accompanied by an increase in the average molecular weight and viscosity.

Branched oligomers due to the asymmetric structure have a more loose structure, are not crystallized with a certain optimal ratio of branching, it is easier to form clubs in cooling, their rheological properties are less dependent on the molecular weight and temperature.

Polydimethylsiloxane fluids

The widest use in the technique has received the easiest class of silicone liquids - polydimethylsiloxanes.

Basically, in practice two types of polydimethylsiloxanes are applied:

they have an industrial brand "PMS-P" and differ among themselves according to the total number of units N and M, and in terms of the ratio of these links.

The polydimethylsiloxane liquids of the cyclic structure in industry are rarely used. One of the few examples can be the PMS-200A liquid, which is a mixture of linear and cyclic oligomers, and used mainly as a foaming additive.

Linear polydimethylsiloxanes

Molecules linear The polydimethylsiloxanes are built regularly, symmetrically. Only an end, trimethylsiloxy group, which, by the mobility of methyl radicals, located at the silicon atom, forms the similarity of the "umbrella" structure, disrupts the symmetry. This feature of the structure of linear polydimethylsiloxanes causes their ability at low temperatures (-60 ° C ... -70 ° C) to form crystal structures.

In low molecular weight oligomers, the formation of crystalline structures interferes with the close location of the end groups. In such oligomers, crystallization can manifest itself at -70 ° C ... -82 ° C. In longer chains, when the end groups are separated by a long, regularly constructed chain, the ability to form crystalline structures appears already in the temperature range -40 ° C ... -60 ° C. In this temperature range, polydimethylsiloxanes lose mobility and crystallize long before the glass transition temperature of -123 ° C.

The flexibility and spiral structure of the polydimethylsiloxane molecule determines the rheological properties of oligomers. Depending on the value of the NCR. They have viscosity from 0.65 to 1 × 106 mm2 / s. In practice, it is viscosity that acts as the main operational characteristics of polydimethylsiloxanes. The viscosity of polydimethylsiloxanes monotonically increases with an increase in their molecular weight.

The refractive index, density and surface tension, as well as the activation energy of the viscous flow of silicone fluids increase as the viscosity increases, asymptotically approaching certain limit values, and further remain constant, independent viscosity. The limit values \u200b\u200bof the main physical properties are achieved in polydimethylsiloxanes with a viscosity of about 500 - 1000 mm2 / s. This circumstance gives the basis to divide them into two groups: low grade, for which the dependence of viscosity properties is observed, and highly viscous, for which such dependence is not observed. Polydimethylsiloxanes - representatives of these groups behave in different ways during the flow: the first are newtonic fluids, for the second, an abnormally viscous course is characterized.

The relatively low values \u200b\u200bof the density of liquid polydimethylsiloxanes (820-980 kg / m3) are explained by the presence of free rotation of the methyl groups around the Si-C bond, which does not stop even at a temperature of -196 ° C. An additional loose effect on the packaging of molecules in polydimethylsiloxanes has the rotation of individual fragments of molecules around the Si-O connection.

For silicone liquids, a high magnitude of compressibility is characterized, which is associated with a spiral structure of molecular chains, elastically deforming under pressure. For example, the relative change in volume at 25 ° C with a change in pressure from 0.1 to 10 MPa for PMS-1 is 8.8%, PMS-100 - 7.3%, while the relative change in the volume of paraffin or fluorocarbon oils under such conditions does not exceed 4.45 - 4.95% .

Liquid polydimethylsiloxanes have a low surface tension, which at 20 ° C increases from 15.5mn / m to 21 MN / m for polydimethylsiloxanes with a viscosity of 100 - 150 mm2 / s and above and then does not change. Low surface tension of silicone liquids causes their good spreadability on various surfaces and the ability to exercise water-repellent properties, which is widely used in practice.

With an increase in viscosity, the boiling point of liquid polydimethylsiloxanes increases to 300 ° C, and starting with PMS-100 remain constant. This phenomenon is associated with the beginning of the depolymerization of the siloxane chain at 300 ° C, when the boiling of the oligomer is associated with the release of lower molecular weight of depolymerization products.

Low viscosity polydimethylsiloxanes in normal conditions are bad. The polydimethylsiloxanes with a larger molecular weight are not burning themselves, but when heated is depolymerized with the formation of volatile dimethylcyclosyloxanes, capable of burning.

Dimethylsiloxane branched buildings

Dimethylsiloxanes branched Buildings - dimethyl (methyl) Siloxana - We are produced under the brands of PMS-P and a digital index characterizing the magnitude of kinematic viscosity. Like their linear analogs, they are colorless transparent fluids with a viscosity from 1 to 400 mm2 / s. Similar to dimethylsiloxanes, dimethyl (methyl) siloxanes are mixtures of molecules with different degrees of polymerization, however, their composition is complicated by the composition of dimethylsiloxanes, since dimethyl (methyl) siloxanes may be kept with molecules of different degrementary branching and molecules of a pure linear structure.

The main difference between dimethyl (methyl) siloxanes of the branched structure from similar ones on the viscosity of linear dimethylsiloxanes is the absence of a tendency to crystallize with a certain content of branching methylsylsexican links. Such dimethyl (methyl) siloxanes during cooling is noticeably losing fluidity under the influence of small shear efforts at a temperature of about -110 ° C, and then glass. When heated Dimethyl (methyl), siloxanes immediately go into a viscous state.

The main reason for suppressing crystallization in dimethyl (methyl) siloxanes is considered to be a violation of the regularity of the structure of siloxane chains with the introduction of methylsyl seschaoxane units into their composition. The optimal relationship between methylsylsexic acid and dimethylsiloxile glands in the oligomers of the PMS-P-type oligomers should consider the ratio of the order of 1: 5, in which the minimum temperature of the solidification of the compositions of the composition under consideration is observed regardless of the average length of their chains within 8-50 units. With a smaller ratio of methylsyl chase and dimethylsiloxilers in oligomers, there is a sharp increase in the frost temperatures due, probably crystallization of linear dimethylsiloxane chains contained in such oligomers, involving the crystallization and sections of the chains with dimethyl oxyloxyls of branched molecules. With a greater value of the specified ratio, the increase in frosted temperatures occurs due to an increase in intermolecular interaction in such oligomers and a significant increase in their viscosity.

According to the physical properties of Dimelil (methyl), siloxane fluids are very close to their analogues of the linear structure. Not only the properties of the oligomers of PMS and PMS-P at 20 ° C, but also the nature of their change with a change in temperature and pressure. Temperature dependences of the viscosity of dimethyl (methyl) siloxanes and similar dimethylsiloxanes coincide. As in the case of dimethylsiloxanes, with an increase in pressure, a significant increase in viscosity is observed and the greater the lower the temperature.

The dielectric permeability of dimethyl (methyl) siloxans is somewhat higher than that of the dimelilsiloxanes of the same viscosity, and this distinction remains at high temperatures.

Brands and areas of application of polymethylsiloxanes

Assortment of polymethylsiloxanes

Of the entire range of silicone liquids, it is polydimethylsiloxanes that are most fully represented in the market. In the domestic industry, these are widely known dimethylsiloxane fluids produced in accordance with GOST 13032-77.

PMS and PMS-P liquids possess a wide range of properties depending on the composition, structure and molecular weight. The main indicator that determines the areas of their application, as already mentioned, is a kinematic viscosity, the value of which is included in the liquid brand. Oligomers of this group of organosiloxanes are classified by applications as follows:

• pMS-1 ÷ PMS-2 liquids are used as cooling and damping fluids in devices up to -60 ° C;
• pMS-10 ÷ PMS-1000 fluids are used as damping, depreciation, hydraulic fluids in devices and mechanisms, as well as dispersion media for plastic lubricants, vaselines and pastes, well-proven themselves, in particular, shut-off armature gas pipelines;
• liquids with a viscosity above 10000mm2 / s are used as damping fluids in devices, dampers of tweeted oscillations in heat-building and as dispersion media in highly viscous plastic lubricants;
• fluids with an extensive structure of molecules of PMS-1R ÷ PMS-3P are used in devices and mechanisms as cooling and damping up to -100 ° C, and PMS-10P ÷ PMS-400R as dispersion media in low-temperature oils and lubricants and damping fluids.

From foreign analogues of PMS liquids, you can mention linear silicone fluids Wacker AK Silicone Fluidmanufactured by the German company Wacker, and having kinematic viscosities from 0.65 to 10,000,000 mm2 / s.

Since dimethylsiloxane fluids have low surface tension values \u200b\u200b(18-20 MN / m), they are also widely used as antipine additives into mineral oils. A good spreadability and absence of bubbles in varnishes and coatings, as well as a high polishing ability in the polyturks, give the PMS liquid with small additives to the specified materials.

The dielectric properties of dimethylsiloxanes and the nature of their dependence on temperature indicate the high dielectric qualities of PMS liquids. If this takes into account that silicone fluids do not form conductive carbon particles during electrical sample or sparking, then their use becomes clear as liquid dielectrics in transformers and other electrical devices. It has proven itself as a transformer fluid polydimethylsiloxane fluid PowerSil Fluid TR 50 Firms Wacker.

Missing Properties of PMS Liquid

PMS liquids have low lubricating properties with friction steel according to steel, but some combinations of rubbing steam, for example, bronze - steel, brass - plastics, with hydrodynamic lubricant with liquid polydimethylsiloxanes work satisfactorily. The use of PMS as liquid media in oils and lubricants compounded by different anti-wear additives and dispersion creates favorable conditions for selective adsorption of additives on the friction surfaces and for the formation of an anti-wear film, which allows to significantly increase pressure and sliding speeds.

Liquid polydimethylsiloxanes are corrosion-inert

Liquid polydimethylsiloxanes are corrosion-inert substances. Under normal conditions and when heated to 100 ° C - 150 ° C, they do not cause corrosion and do not change themselves for a long time when air transmitted in contact with aluminum and magnesium alloys, bronze, carbon and alloyed steel, titanium alloys. The properties of PMS liquids do not change at temperatures up to 100 ° C in the air atmosphere for 200 hours when contacting the alloys listed. At temperatures of 65 ° C - 100 ° C, the PMS do not change its viscosity and do not cause significant swelling or leaching many polymers and polymeric materials.

Silicone liquids biologically inert

Another useful feature of silicone fluids is their biological inertness, so they are widely used in medicine, cosmetics and even in the food industry.

For example, food additive E900. represents nothing more than liquid polydimethylsiloxane and plays the role of a foamber at industrial production Foods. Also, the additive is used as a binder agent, a stabilizer, a texturerator, an anti-killer and an antisoler.

Mainly food antiflamming E900 is added to the fryer fats and oils, some types of juices, canned fruits and vegetables, which are produced in both glass and metal containers. In addition, the substance is often part of the jams, marmalade, joy, jelly, and other food products, the basis of which is fruits.

In addition, the E900 additive can be found in products that are made of grain, in concentrated, and then canned broths and soups. Polydimethylsiloxane is added to non-alcoholic beverages, wine, cider, liquid whipped dough, ready-made mixes for omelets, as well as chewing gum.

Starting from the 70s of the 20th century, silicone fluids are actively used in personal care and decorative cosmetics. CyclineSiloxane D5 and polydimethylsiloxane received the greatest distribution, known in cosmetics dimeticon. Among the most common tasks of silicones in cosmetics: Moisture preservation, color preservation, smoothing hair and leather, fixing the means on the skin, counteracting the penetration into a humidity or sweat product. Silicons do not leave the feeling of stickiness or fatty. Their property to keep the product on the skin is used in waterproof products, as well as in sunscreen. Dimethicone is found in most popular Pantene shampoos.

The influence of substituents at the silicon atom on the properties of oligomers

If, in the frame of siloxane chains, it is possible to change the organic part, starting with the monotone structure of dimethylsiloxane molecules only with methyl groups at the silicon atom and entering their structure elements of asymmetry, rigidity, polarity, conformational inhibition, etc., the properties of oligomers are significantly changed.

This phenomenon is confirmed by the change in the properties of organosiloxanes as the structure of dimethylsiloxanes complicates, by replacing parts of methyl radicals into other alkyl or aryl radicals in them. Introduction to the frame of the chain of molecules, for example, alkyl groups with a number of carbon atoms, two or more and isothing instead of methyl silicon atoms, significantly affect the viscosity, glass transition temperature and frost, the activation energy of a viscous flow and the temperature coefficient of viscosity. Increasing the number of carbon atoms in alkyl chains, that is, the growth of the carbon chain's length naturally lowers the density, increases the temperature of the frozen and glass transition, the refractive index, the energy of the viscous flow coefficient and the temperature coefficient of viscosity. Such changes can be explained, on the one hand, the increase in the structure of the oligomer molecules structure, leading to a decrease in the packaging density, on the other, is an increase in intermolecular interaction and a decrease in conformational mobility due to an increase in the number of intermolecular engagement between long alkyls.

The same effect on the rheological properties of oligomers is observed when used in the frame of the dimethylsiloxane chains of other types of asymmetry, for example, the introduction of hydrogen atom at the silicon atom or branching due to the trifunctional link in the chain.

Polydyethylsiloxanes

When replacing both methyl radicals at the silicon atom ethyl, we face a new class of organosiloxanes - polydyethylsiloxanes- which have gained great practical importance. Diethylsiloxanes are a mixture of polymer generations predominantly linear structure of the general formula


In addition to cyclic compounds [(C2N5) 2SIO] N and branching structure oligomers.

Diethylsiloxanes are transparent liquids with a viscosity of 1.5 to 1 × 106 mm2 / s, depending on the degree of polymerization. These liquids have significantly lower glass transition temperatures and frozen in comparison with dimethylsiloxanes, but the effect of temperature on their viscosity is significant. Diethylsiloxanes have a higher viscosity at 20 ° C than methylsiloxanes with a comparable chain length. The main difference between diethylsiloxanes is an extremely low fluidity loss temperature, which is 1.5 - 2 times lower, and reach -135 ° C ÷ 140 ° C.

In the domestic industry, polydiethylsiloxanes are produced under brands PES.. They are well soluble in most organic solvents and, unlike other organosiloxanes, are fully combined with mineral oils, which led to widespread use of oils and lubricants.

The composition of industrial diethylsiloxanes is complicated, in general, they are mixtures of molecules of different degrees of polymerization and various structures from purely linear to branched and cyclic.

The replacement in organosiloxans of methyl substituents into ethyl limits the freedom of rotation of atoms and groups around the links ≡Si-O- and ≡SI-C≡. This leads to an increase in the rigidity of the chains and thereby prevents the implementation of the spiral conformations of siloxane chains and the complete intramolecular compensation of the dipoles of polar bonds ≡Si-O-. The extensive structure of some diethylsiloxanes has the same effect.

On the other hand, ethyl substituents and branching prevent the tight packaging of chains, which leads to large intersection distances in diethylsiloxanes compared with dimethylsiloxanes and to a decrease in intermolecular interaction.

The prevailing area of \u200b\u200bapplication of polydiethylsiloxane fluids:

• PES-1.,
• PES-2.,
• PES-3.,
• PES-4.,
• PES-5.,
• PES-7.,
• PES-C-1 (liquid 132-24),
• PES-C-2 (liquid 132-25).

This is the use of them as a dispersion medium in oils and upright.

Temperature limits of liquid PES operating limits lie in the temperature range from -70 ° C ÷ -100 ° C to 125 ° ÷ 150 ° C.

Depending on the viscosity of the PES are classified by applications as follows:

• PES-1, PES-2 - low grade with glass transition temperatures up to -140 ° C - are used as cooling coolants and working fluids in hydraulic systems;
• PES-3 - in hydraulic systems and as a component of polishing compositions;
• PES-4, PES-7 with viscosity in the range of 42-48 mm2 / s at 20 ° C and with low glass transition temperature (-130 ° C) are well mixed with oil oils and other organic oils, used as the basis of low-temperature instrument and hydraulic liquids and oils;
• PES-5 is a coolant, damping fluid in devices, dispersion medium in plastic and separating lubricants, components of polishing and cleansing compositions, a lubricant in the production of synthetic fibers.

Based on the PES created widely known cyatim-221 lubricants, VNIIINP-207, 219, 231.

A distinctive feature of liquid polydimethylsiloxanes is complete compatibility with mineral oils and other organic products. The additive of the PES to hydrocarbons improves the low-temperature characteristics of the latter. So mixtures of PES-4 with MS-14 and AU oils have lower fluidity loss temperatures and satisfactory viscosity at a temperature of -50 ° C.

In some optimal ratios of the mixture of diethylsiloxanes with hydrocarbons, high lubricant activity exhibit. It is assumed that the mechanism of action of the additives of organosiloxanes to oil oils is the decomposition of dotethylsiloxanes when friction with the formation of two surface layers: the first very high solidness (silicon) and the second is a soft layer of oxides that performs the lubricant function. It is also possible to form chemical compounds of another composition that reduce friction. The ratio of these two layers is determined by the lubricating properties of diethylsiloxane solutions in hydrocarbon environments.

When using mixtures of polydimethylsiloxanes and mineral oils created dashboard low-temperature oils brands 132-07, 132-08, 132-19, 132-20, 132-21, instrumentation lubricants OKB-122-7, OKB-122-7-5, MZ-5, frost-resistant lubricants Severor-1, UNIZOL-3M.

Polydiethylsiloxane fluids are used as working oil diffusion vacuum pumps. They are produced under the brand PES-B. and differ from organic vacuum fluids with increased thermal oxidative stability.

Polymethylphenylsiloxanes

With the introduction of the chain of organosiloxanes of phenyl radicals, a separate extensive group is formed polymethylphenylsiloxanes with specific specified properties.

Polymethylphenylsiloxane fluids differ in the structure of molecules and at the ratio of methyl and phenyl radicals in them.

(I)

(Ii)


R3-Si- \u003d (CH3) 3-Si-, (CH3) 2 (C6H5) -Si-, (CH3) (C6H5) 2-Si- or (C6H5) 3-SI-.

The chains of polymethylphenylsiloxane molecules may consist of methylphenylsiloxyls (I) or dimethyl- and methylphenylsiloxide (II) or dimethyl and diphenylsiloxes. With the same ratio of methyl and phenyl radicals, their properties are close. The structure of molecules is the most significant effect on the properties - linear or cyclic.

Linear molecules methylphenylsiloxanes There may be a wide range of molecular masses, which determines their viscosity.

Cyclic methylphenylsiloxanes Do not reach significant values \u200b\u200bof molecular masses. Methylphenylcyclotry or tetrasiloxanes or a mixture of three, tetra and pentaticlosyloxanes with different ratio of dimethyl-methylphenyl or definylsiloxyls are used with different ratios in them.

The domestic industry produces a large number of grades of polymethylphenylsiloxane fluids of various purposes, which can be divided into 4 groups.

Group I - ω, ω'-hexamethyloligodimethyl (methylphenyl) siloxanywhich are polydisperse mixtures of linear molecules of the general formula.


with different polymerization degrees and different ratio N: M (from 10 to 1.5). The distribution of methylphenylsiloxes in molecules has a statistical character.

The following brands of methylphenylsiloxane include this group: FM-5., FM-5., 6Ap, 133-79 (or FM-1322.), Copolymer 2., FM-6, FM-6VV., 133-158 (or FM-1322/300), Copolymer 2/300, Copolymer 5., Copolymer 3..

Group II - ω, ω'-hexamethyloligomethylphenylsiloxaneAlso representing polydisperse mixtures of linear molecules of the general formula


Various degrees of polymerization. This group includes liquid PFMS-2 / 5l, PFMS-2. and PFMS-4..

Group III - ω, ω'-dimethyltetraphenyloligomethylphenyloligomethylphenylsiloxaneswhich are polydisperse mixtures of the molecules of the general formula


c varying degrees of polymerization. The brands of industrial produced liquids of this group: FM-1, FM-2, 133-165 (or PFMS-5.), 133-57 (or PFMS-6.).

Group IV - Oligomethylphenylsiloxanes of two brands. Oligomer 133-35 (or MFT-1) represents tetramethyltoTraphenyl cyclotterasiloxane, and oligomer 133-38 (or PFMS-13) - MOE methylphenyl cyclosyloxanes General formula

All polymethylphenylsiloxanes are transparent colorless or slightly yellowish liquids. The most viscous oligomers - 133-165 and 133-57 - can be painted from light yellow to light brown.

From foreign methylphenylsiloxane fluids, Wacker liquids have proven well - Wacker AP 200 Silicone Fluid, Wacker AP 1000 Silicone Fluidrepresenting polydimethylsiloxane fluids with high content of phenyl groups, Wack ER AR 200 Silicone Fluid, as well as Wacker AS 100 Silicone Fluid with low fractions of phenyl groups.

The introduction of phenyl groups into organosiloxanes significantly increases the level of intermolecular interactions due to an increase in the rigidity of the chains of molecules, limiting freedom of rotation of atoms and groups of atoms around the bonds ≡Si-O- and ≡SI-C≡, as well as due to the appearance of specific intermolecular interactions due to the presence As part of the oligomers of aromatic nuclei. As a result, the physical properties of oligomers change.

The main difference between polymethylphenylsiloxane fluids from polydimethylsiloxanes is in increased heat-oxidative and thermal resistance. Phenyl radical in silicon atom in combination with methyl increases the thermal and thermo-acid stability of organosiloxanes by 50 ° C - 70 ° C, increasing the melting point, as well as the dependence of viscosity on temperature. A particularly strong effect on the heat resistance and other properties of methylphenylsiloxanes has the number of phenyl radicals in end groups of oligomers.

Methylphenylsiloxanes also have increased radiation resistance, the aryl groups of which, as in organic arylene, dispel the energy of the radiation with the conjugate double bonds of aromatic rings.

The main directions of the practical application of methylphenylsiloxane fluids:

• high vacuum oils for diffusion pumps;
• coolants for high and low temperatures;
• dispersion media for heat-resistant oils and lubricants.

The limit of permissible temperatures of using methylphenylsiloxanes lies in a wide range from -20 ° C ÷ -100 ° C to 200 ° C ÷ 350 ° C, depending on the composition, the degree of polymerization and the content of phenyl substituents in molecules.

The combination of increased heat resistance, low temperature of glassware characteristic of methylphenylsiloxanes, low-pressure vapors, compatibility with organic media determines the areas of their use that can be classified according to the marks of oligomers as follows:

• fM-5, FM-6 liquids, FM-5,6AP are used as dispersion media low-temperature oils and lubricants, in low-loaded high-speed ball bearings and freon refrigeration machines, as well as cooling coolants;
• liquids 133-79, 133-158, copolymer 5 and copolymer 3 are used as heat-resistant and low-temperature media in oils and lubricants operable in a wide range of temperatures and in deep vacuum. They are also used as coolants and liquids for hydraulic systems;
• pFMS-2 / 5L fluids, FM-1, FM-2, 133-35 and 133-38 are used in diffusion vacuum pumps with an extreme vacuum from 133.322 NPU to 13.332 MCPA;
• fluids of PFMS-4, 133-165 and 133-57 are used as high-temperature and hard-fired coolants, dielectrics, workers and dispersion media for lubricants and oils, fixed phases of gas-liquid chromatography.

The areas of use of methylphenylsiloxanes to obtain consistant lubricants are covered both heat-resistant lubricants, vacuum antifriction and special instrumentation, electrocontact, sealing and nontasted lubricants.

The most valuable and high-quality materials based on methylphenylsiloxanes, which are not available for vacuum properties of analogues among other classes of chemical compounds, are diffusion oils for high-vacuum pumps to the limit vacuum in the pump to 13.3 MCP.

Polar groups or atoms in organic radicals of organosiloxanes contribute to the properties of oligomers. They are usually used to increase the lubricating properties of organosiloxane fluids while maintaining the main properties or to achieve other specified characteristics.

Methyl (halogenorgano) Siloxana

Typical representatives of such oligomers are organosiloxanes with halogen in organic radicals - methyl (halogenorgano) Siloxana. They become more polar, have improved lubricating ability and limited flammability, their solubility and compatibility with organic media change. At the same time, the level of intermolecular interaction, viscosity and its dependence on temperature, temperature of frozen and glass transition increases. However, these undesirable changes are compensated by a significant increase in lubricity and polarity.

The structure of methyl molecules (halogenorgano) of siloxanes, as well as other organosiloxanes, may be linear, branched or cyclic, and all the patterns of the properties of oligomers associated with the structure of molecules, for these oligomers are similar to other organosiloxanes.

The domestic industry produces three types of methyl (halogenorgano) siloxanes:

• methyl (chlorophenyl) siloxany,
• methyl-γ-trifluoropropylsiloxanes
• methyl (halogenorgano) siloxanes containing both γ-trifluoropropyl and chlorophenyl substituents.

All methyl (halogenorgano) siloxanes are transparent colorless or light yellow liquids, well-soluble in such polar solvents such as acetone, methyl ethyl ketone, ethyl acetate, isopropyl alcohol, freon 13, etc.

By nature, industrial methyl (halogenorgano) siloxanes are complex mixtures of molecules, differing from each other as a degree of polymerization and composition.

Dimethylchlorophenylsiloxanes

Currently, dimethylchlorophenylsiloxanes are widely used as lubricating substances. It is believed that atoms in chlororganosyloxanes are activated in hot spots when the metal friction about the metal and the chlorine atoms with the metal form a thin film of metal chloride on the surface, which helps to reduce the friction forces and prevents mealing. The activity of chlorine atoms Dimethyl (methyl chlorophenyl) siloxanes under friction depends on their number in the phenyl radical, the location of chlorophenyl radicals in the polymer chain and on the total chlorine content in oligomers.

The study and comparison of the lubricating properties of organochlorophenylsiloxanes and organofluoropropylsiloxanov showed that under the boundary friction, the mechanism of lubrication of the rubbing pairs is differ. Without going into details, the final output of the study is interesting - with small loads, lubricating properties are better at dimethyl-methyl-γ-trifluoropropylsiloxanes, and at high - at oligodimelle-methyl chlorophenylsiloxanes.

It turns out that in order to obtain liquid oligomers with good lubricating properties in a wide range of loads, it is advisable to combine the specified two types of organosiloxanes into one system.

The simultaneous presence of dichlorophenyl and γ-trifluoropropyl radicals in the organosiloxane molecule gives the synergism effect under boundary friction. Accordingly, dimethyl- (methyl chlorophenyl) - (methyl-γ-trifluoropropyl) siloxanes possess the best lubricating properties than dimethyl-(methyldichlorophenyl) siloxanes and dimethyl-methyl-γ-trifluoropylsiloxanes, separately taken. Such silicone fluids are manufactured by industry ( fluids 169-36, 169-106, 169-168).

So, the main applications of methyl (halogenorgano) of siloxanes are lubricants and fluids operating under conditions of boundary and hydrodynamic friction.

One of the most significant applications are hydraulic systems operating at elevated temperatures (200-250 ° C). For these purposes, dimethyl (methyldichlorophenyl) Siloxan liquid Xc-2-1 was created, which does not cause corrosion at temperatures up to 250 ° C for 100 hours of aluminum alloys AL-9, bronze, steel SHX-15, 12HNZ.

Methyl liquids (fluororeorgano) of siloxanes with appropriate anti-wear additives and antioxidants have good lubricant properties at temperatures up to 300 ° C using friction sites operating in hydrodynamic mode.

Methyl phtroorororganosiloxanes are operational at temperatures up to 250 ° C in hydraulic systems, hydraulic surfactants and other systems with stained steel nodes, possessing in such conditions with an increased lubricant and stable characteristics.

Methyl (halogenorgano) Syloxans are successfully used as dispersion media for heat-resistant (up to 250 ° C - 350 ° C) lubricants with thickeners, lithium soaps and various antioxidants. Some of them are functionable in vacuo to 10 NPA at temperatures from -80 ° C to 160 ° C in low-loaded rolling bearings and low-power gearboxes operated in high vacuum.

IN lately New unique areas of use of methylfluorodorganosyloxanes and oligomethyl phtorochlorororganosyloxanes for preservation of products and objects of material culture from wood, ceramics, skin, etc. In order to protect them against insect destruction (vertices) and from the action of adverse factors ambient. These oligomers turned out to be highly efficient anti-speakingrs in the chemical cleaning of clothing. Based on methyl (halogenorgano) siloxanes developed a composition 137-183 having a "plastle" name for the manufacture of blinds and ties of paleontological and archaeological objects representing a large scientific and artistic value.

Treatment based on methyl (halogenorgano) Syloxans 169-116 Having a brand "Antisheshelin" turned out to be biologically active in relation to insect-tree-bodies, completely destroying them at small doses (0.1% solution), while remaining non-toxic with respect to warm-blooded organisms.

Organoalkoxysiloxanes

The problem of increasing the lubricity and surface activity of organosiloxanes along with the conservation of heat resistance and compatibility, with different media led to the study and synthesis of an extensive group organoalkoxysiloxanes.

In practice, organs (2-ethylGexoxy) siloxane fluids are most widely used.

The main impact on the properties of this series of oligomers is the volume and nature of an organic radical. Especially sensitive to these factors refractive factor, viscosity, frosted temperature, the activation energy of a viscous flow, i.e. Characteristics associated with the polarity of the radical, intermolecular interaction and conformational mobility of molecules. The temperature of the frozen majority of the oligomer under consideration lies below -100 ° C or near this value, which is explained by the asymmetry of the structure of molecules that prevents dense packaging and crystallization during cooling.

Among the developed and investigated organicoxysilanes, phenyl-(2-ethylhexoxy) of siloxanes possess better operational properties ( PFGOS-4. and PFGOS-3.) and thienil- (2-ethylhexxoxy) Syloksan ( PTHOS-3.). These oligomers are well lubricating rubbing metal pairs, mixed with many organic and fluororganic liquids and oils, have high activity as defoamers, inert to freon and structural materials used in refrigeration machines. They are stable at temperatures up to 150 ° C and frozen at temperatures below -65 ° ÷ -75 ° C. Such a complex of properties has determined the applications of these Organosiloxanes.

Due to good compatibility with freon, the oligomer of PFGOS-4 is used as lubricating oil in refrigeration. PFGOS-4 oil in a mixture with Freon F-22 inert with respect to IRP-1068 rubber, graphite, cured bakelite lacquer. It is also recommended for use for hard-loaded high-speed compressors. In addition, it is tested and recommended as a lubricant oil for insulteable compressors with compactors from fluoroplastic rings.

Good dielectric properties of the oligomer of PFGOS-4 allow it to apply it for the electrocontact paste. PFGOS-4 oil is good foam in water-glycol mixtures. Taking into account this property based on it developed water-glycol cooling fluids for engine engines and for injection molding machines.

The PFGOS-3 liquid is used in hydraulic clutches of the bottomhole conveyors and most fully meets the requirements for shock absorbing fluids for car and tractor buildings.

Reactive organosiloxanes

Among the various groups of silicone fluids are a mansion reactive Organosiloxans who found wide practical use For hydrophobization of the surface of various materials, - alkylhydridsiloxanes and alkylsiloxanolates Alkaline and other metals.

Representatives of the first are methyl hydridexiloxanes and ethylhydridsiloxanes. In both cases, an ≡SI-H bond is associated with respect to the active surface, which easily interacts with hydroxyl groups or oxygen bond - metal, forming a valence ≡Si-O-connection with the surface of the material. The alkyl radical associated with the silicon atom, while oriented from the surface, giving it hydrophobic properties. Thus, the finest polyalkilsiloxane film is formed on the surface, not washed and not removed by conventional methods.

Molecules of such oligomers can be linear


or cyclic

The reactivity of such oligomers is different. In the case of an alkyl hydride cyclosyloxane, the active surface can not only interact with ≡Si-H bond, but also cause the disclosure of a Si-O-Si cycle and interact with the bonds of the disclosed cycle by the type of telomerization reaction. Such an opportunity makes alkyl hydridcyclosyloxanes of more versatile hydropobizers, which is implemented in practice in hydrophobic fluids GKJ-94. and GKG-94M.

The main areas of application of alkyl hydridexiloxanes are construction, textile and light industry.

In hydropobicators of the type of alkylsoxanolates of metals


(R - Alkyl, Me - Na, Al)
reactive with respect to the surface building materials It is the connection of ≡Si-OME, which in reacting reacts with hydroxides or salts (for example, cement), also forms polyalkylsiloxane film. This film, tied with siloxane bond to the surface, also has surface-oriented alkyl radicals that give it hydrophobic properties.

On a large industrial scale, alkylsikonates sodium are available and found: GKJ-10 (etilsiconate sodium) and GKG-11 (sodium methylsiconate). They are soluble in water, do not smell, are not dangerous in circulation.

Colorganic hydropobicators were widely used in construction to increase durability and primarily the frost resistance of heavy and light concrete and reinforced concrete in difficult conditions: with alternate freezing and thawing, moisturizing and drying, capillary sacrifice and evaporation of salt solutions, as well as with long and continuous exposure. salts solutions.

HC-94 liquids, GKG-10 and GKZH-11 are used to hang the fracture resistance and the forms of heavy and lung concrete. The GKG-10 and GCG-11 increase the weather resistance of cement-sand solutions, concrete, bricks, gypsum, tuffs, limestone, as well as the durability of coatings from silicate and limestone paints.

Conclusion

Silicone fluids discussed above are most widely used in industry different areas. Nevertheless, research continues to obtain and study the properties of many other classes of silicone liquids. For example, rather promising classes are organosiloxane fluids with volumetric radicals at the silicon atom (adamantyl, carbran), organosiloxanes with heterorals, heterocycles and heteroatoms.