RU2017757C1 - Oligotrimethylhydride siloxanes as impregnated and finishing agents for wood, and a method of their preparing - Google Patents

Abstract

FIELD: agents for wood treatment. SUBSTANCE: product: oligotrimethylhydride siloxanes of formula

Description

O

(SiO₂)

(HSiO_1,5)

CH₃, где n = 0,8-1,2;
m = 0,8-1,2, которые могут быть использованы в качестве пропиточных, отделочных материалов для древесины.The invention relates to the field of production of new organohydridesiloxanes, namely oligotrimethylhydridesiloxanes of the general formula
CH

O

(SiO ₂ )

(HSiO _1.5 )

CH ₃ where n = 0.8-1.2;
m = 0.8-1.2, which can be used as impregnating, finishing materials for wood.

 Organohydride siloxanes used as wood impregnation agents should include organic groups, for example methyl groups, connected directly to silicon, dissolve well in available solvents and not impair the appearance of the processed material.

где n = 9-10, которые получают гидролизом этилдихлорсилана (С₂Н₅)НSiCl₂ водой в присутствии бутилового или этилового спирта с последующими разделением на органическую и водную фазы, нейтрализацией органического слоя и отгонкой керосина. Полученные по этому способу олигоэтилгидридсилоксаны характеризуются содержанием активного водорода - 1,2 мас.%, мол. массой 680-740. Использование этих силоксанов в качестве пропиточных средств для древесины не позволило получить качественной защиты древесины от воды, а также лучше выявить текстуру древесины, которая определяется визуально и оценивается в баллах. В данном случае оценка текстуры 1-2 балла.Known oligoorganohydride siloxanes [1], used as an impregnating agent for wood [2], namely oligoethyl hydride siloxanes of the General formula

where n = 9-10, which are obtained by hydrolysis of ethyl dichlorosilane (C ₂ H ₅ ) НSiCl ₂ with water in the presence of butyl or ethyl alcohol, followed by separation into organic and aqueous phases, neutralization of the organic layer and distillation of kerosene. Obtained by this method, oligoethylhydride siloxanes are characterized by a content of active hydrogen of 1.2 wt.%, Mol. weighing 680-740. The use of these siloxanes as an impregnating agent for wood did not allow to obtain high-quality wood protection from water, and it was also better to identify the wood texture, which is determined visually and scored. In this case, the texture score is 1-2 points.

(

O_4-а)

SiR₃, где a = 0-3;
R - водород, метил, этил,
используемые для пропитки древесных материалов [4], которые получают гидролизом алкоксисиланов в присутствии кислоты.Closest to the oligomethyl hydride siloxanes of the invention are known oligomethyl hydride siloxanes [3] of the general formula
R ₃ SiO

(

O _4-a )

SiR ₃ where a = 0-3;
R is hydrogen, methyl, ethyl,
used for the impregnation of wood materials [4], which are obtained by hydrolysis of alkoxysilanes in the presence of acid.

At the first stage, chlorosilanes of the formula R _a SiCl _4-a are esterified, where a = 0-3, R _a is methyl, ethyl and at least 1 hydrogen atom, and aliphatic alcohol is methyl or ethyl.

In the second stage, a disiloxane of the formula (R ₃ Si) ₂ O and a silane of the formula R _a Si (OR) _4-a , in which R is methyl, ethyl and at least one hydrogen atom present in at least one of the reactants, are reacted .

The reaction is carried out as follows: in a heated mixture of disiloxane (DS), water and concentrated hydrochloric acid, organoalkoxysilane (OAS) is introduced with stirring for 2 hours in a molar ratio of DS: OAS = 1: 1-3. Upon completion, bring the mixture to a boil. Then it is cooled to 60 ^° C, soda is added and stirred for 15 minutes. After separation of the aqueous layer, the organic layer is dried over sodium sulfate. Characteristics of the obtained products are given in table. 2.

 However, when using these oligoorganohydridesiloxanes as an impregnating agent for wood, it was possible to only slightly reduce the water absorption of wood. At the same time, when using these oligoorganohydridesiloxanes to better identify the texture, it is necessary to apply preliminary treatment of the wood surface with special solutions containing Montana wax or Carnauba wax.

 The objective of the invention is the synthesis of oligotrimethylhydride siloxanes, which can be used as an impregnating and finishing agent for wood, reducing water absorption with constant moisture exchange and better revealing the texture of wood.

This problem is solved by oligotrimethylhydride siloxanes of the general formula (CH ₃ ) ₃ Si-O- (SiO ₂ ) _n - (HSiO _1,5 ) _m -Si (CH ₃ ) ₃ , where n = 0.8-1.2; m = 0.8-1.2, obtained by esterification of a mixture of three chlorosilanes selected from the group consisting of silicon tetrachloride, trichlorosilane, trimethylchlorosilane or a waste product and separation of methylchlorosilanes, including, wt.%:
Silicon tetrachloride 10-60 Trichlorosilane 10-40 Trimethylchlorosilane 10-60 Other chlorosilanes 3-7 with a molar ratio of (0.4-0.6): (0.4-0.6): 1, respectively, with aliphatic alcohol C ₁ -C ₄ at a molar ratio of aliphatic alcohol: ≡Si-Cl, equal to (1.0-1.1): 1 and subsequent acidolysis with acetic acid ester obtained at a temperature of 30-80 ^{° C} and washing of the reaction mixture until neutral.

 The difference between the oligotrimethylhydride siloxanes of the invention from the known organohydride siloxanes is the presence of reactive hydride groups in trifunctional siloxyl units and monofunctional units in a molar ratio (0.4-0.6): 1, respectively. The inclusion in the composition of the final oligomer of mono-, tri- and tetrafunctional structural fragments in a given ratio provides a manifestation of a complex of specific surface-active properties that are absent in siloxanes based on only mono- and trifunctional fragments. When the content of hydride trisiloxy or tetrasiloxyl units is less than 0.4 mol per 1 mol of trimethylsiloxyl units, the obtained siloxanes lose their specific surface-active properties and cease to act as finishing agents for wood, revealing its structure (Table 3, Example 5).

 When the molar ratio of trichlorosilane (TCS) or silicon tetrachloride (CCC) and trimethylchlorosilane (TMHS) is more than 0.6: 1, the product cannot be obtained due to the gelation of the reaction mixture.

The oligotrimethylhydride siloxanes of the invention are prepared in the following manner. The starting organochlorosilanes in a molar ratio of CCC: TCS: TMCS = (0.4-0.6): (0.4-0.6): 1 are pre-mixed in the reactor. Aliphatic alcohol C ₁ -C ₄ (methyl, ethyl, propyl, butyl) is added dropwise to a mixture of organochlorosilanes in a molar ratio of 1.1-1 mol of alcohol per 1 mol of active chlorine. The temperature of the reaction mass at this early dropping lowered to 5-10 ^{° C} and increased towards the end of the dropping to 30 ^C. After entering the aliphatic alcohol and 15 min exposure thereto is added dropwise acetic acid in a molar ratio of 1: 1 to the entered alcohol.

The reaction mixture is kept 2 hours after the dropwise addition of acetic acid at 30-40 ^{° C} and 1 hour at 50-80 ^{° C} to complete the reaction. After exposure, the organic layer, which is a solution of oligotrimethylhydridesiloxane in alkyl acetate, is separated from the aqueous and washed until neutral. If necessary, obtaining a 100% oligotrimetilgidridsiloksana its solution is transferred to a topping cube, where alkyl acetate was distilled off at a temperature of 80-110 ^C and a pressure of 400-760 mmHg

The resulting oligotrimethylhydride siloxane has the general formula
(CH ₃ ) ₃ -SiO- (SiO ₂ ) _n - (HSiO _1.5 ) _m -Si- (CH ₃ ) ₃ , where n = 0.8-1.2; m = 0.8-1.2, and is characterized by an active hydrogen content of 0.2-0.4 wt.%., a viscosity of 150-200 cSt, an average molar mass of 350-720.

 Obtaining oligotrimethylhydride siloxanes by the methods proposed in [1,3] failed due to the gelation of the reaction mass at the stage of hydrolysis of chlorosilanes or ethoxysilanes.

 The invention is illustrated by the following examples.

EXAMPLE 1. Into a 2 L reaction flask equipped with a stirrer, dropping funnel, thermometer and reflux condenser connected to the atmosphere through a system of water and alkaline traps, 114.9 ml of CHC, 99.4 ml of TCS, 252 are charged ml of TMHS, which corresponds to the molar ratio of ChHK: THS: TMHS = = 0.5: 0.5: 1. The mixture of organochlorosilanes is stirred for 15 minutes. 388 ml of methyl alcohol (1.1 mol of alcohol per 1 mol of active chlorine) are added dropwise to the resulting mixture of organochlorosilanes at an average rate of 10 ml / min. At the end of the introduction, the reaction mass is stirred for 15 minutes and then 566 ml of acetic acid (1 mol of acetic acid per 1 mol of introduced alcohol) is introduced into it at a rate of 100 ml / min. By the acetic acid entering the end of the reaction mass is heated ^to 30 ° C and kept at this temperature for 1 hour, after which the reaction mixture was heated ^to 50 ° C and held for a further 1 hour at this temperature. After exposure, the reaction mass is transferred to a separatory funnel and the organic and aqueous layers are separated. The aqueous layer was drained, and the organic layer was washed with water until neutral and dried. A solution of oligotrimethylhydride siloxane in methyl acetate is obtained. If necessary, obtaining a 100% solution of the siloxane was transferred to a round bottom flask at 80 ^{° C} and a pressure of 760 mm Hg methyl acetate is distilled off. 200 g of oligotrimethylhydridosiloxane are obtained, which corresponds to a 73% yield from theory.

The resulting product is characterized by an active hydrogen content of 0.35 wt. %, С - 26.13 wt.%, Si - 40.13 wt.%, Н - 6.86 wt.%, Kinematic viscosity 179.5 cSt, M _n = 480.

i

H групп; триплет 0,2 м.д. протоны СН₃-групп от 0-Si-(CH₃)₃-группы.Signals of 4.5 ppm are observed in the PMR spectrum. - signals H from O

i

H groups; triplet 0.2 ppm protons of the CH ₃ groups from the 0-Si- (CH ₃ ) ₃ group.

i

H связи.On the IR spectra, absorption bands of 1255.842 cm ^-1 Si-O bonds in -O-Si- (CH ₃ ) ₃ are observed; 1070 cm ^-1 —Si — O— bonds in Si — O — Si—; 1100 cm ¹ O

i

H connection.

O

i

O ; в области 85,5 м. д. , соответствующие сигналу ядра кремния в группе H

i

O

; в области 10,9 м.д., соответствующие сигналу ядра кремния в группе CH

O

i

или (СH₃)₃-Si-O-(SiO₂), в области 10,0 м.д., соответствующие сигналу ядра кремния в группе (HSiO_1,5)-Si-(CH₃)₃. Олиготриметилгидридсилоксаны, полученные по другим примерам, имеют аналогичные ПМР, ИК, ЯМР спектры.The NMR spectra of ²⁹ Si nuclei show signals in the region of 108.2 ppm, corresponding to the signal of the silicon nucleus in the group

O

i

O; in the region of 85.5 ppm, corresponding to the signal of the silicon core in group H

i

O

; in the region of 10.9 ppm, corresponding to the signal of the silicon core in the CH group

O

i

or (CH ₃ ) ₃ -Si-O- (SiO ₂ ), in the region of 10.0 ppm, corresponding to the signal of the silicon core in the group (HSiO _1,5 ) -Si- (CH ₃ ) ₃ . Oligotrimethylhydride siloxanes obtained by other examples have similar 1 H NMR, IR, NMR spectra.

 The starting materials for the production of oligotrimethylhydridosiloxanes according to Examples 2-8, the conditions for their synthesis and the characteristics of the obtained products are given in table. 2.

 To obtain oligotrimethylhydridesiloxanes in examples 9-14, industrial fractions of the azeotrope CHKh-TMKhS of various compositions are used, which are waste in the production and separation of methylchlorosilanes. At the same time, the necessary amount is added to the calculated amount of TMHS, ChHK, TXS. Use fractions of the following compositions.

 The physicochemical properties of organosilicon siloxanes [3] (examples 2, 4) and oligotrimethyl hydridesiloxanes according to the invention are given in table. 3.

 The oligotrimethylhydride siloxanes of the invention and the known [3] oligomethyl hydride siloxanes (example with active hydrogen) are used as wood impregnation compounds.

The impregnating composition is prepared as follows. Organohydride siloxane is dissolved in a complex solvent of alkyl acetate - isopropyl alcohol to a 2.5% content of the basic substance. Obtained by the proposed method, oligotrimethylhydride siloxanes are already solutions of siloxanes in alkyl acetate. The impregnating composition in this case is prepared by diluting the obtained alkyl acetate solutions with isopropyl alcohol to the required content of oligotrimethylhydridosiloxane. The surface of the wood sample is treated from all sides with the composition until the absorption of the latter ceases. To better identify the texture of wood, the surface to be treated is treated with a special solution containing carnauba wax prior to impregnation with the above impregnating compositions. After treatment the wood is dried and subjected to aging under water for 24 hours at ²⁰ ° C to determine the water absorption and for invariability paropropuskaniya held for 3 days in a saturated humidity air at 20 ° ^C.

 The results are shown in table. 4.

 As follows from the table. 2 and 3, the oligotrimethylhydride siloxanes of the invention and the previously obtained organohydride siloxanes have similar physicochemical properties. However, the proximity of their physicochemical properties does not ensure their equal effectiveness as an impregnating agent for wood. That is, based only on the analysis of the physicochemical properties of oligosiloxanes, the effect that the oligotrimethylhydridosiloxane according to the invention will have on the performance properties of wood cannot be said.

As can be seen from the table. 4, the use oligotrimetilgidridsiloksanov the invention as impregnating agents for wood allows enough convex reveal the structure of wood, to reduce the water absorption of from 40 to 20% at 24 hours immersion in water at ²⁰ ° C at a constant moisture exchange with the environment.

In the preparation of oligotrimethylhydride siloxanes according to the invention, inexpensive and affordable products are used that are multi-ton produced by the domestic industry: CHKh, TKhS, methylchlorosilanes production waste — an azeotropic fraction of ChKhK-TMKhS, any C ₁ -C ₄ aliphatic alcohols. Waste from production is alkyl acetate, which is used to prepare an impregnating composition, and is also a valuable intermediate raw material for organic synthesis and a scarce solvent for paints and varnishes.

Claims (2)

1. Oligotrimethylhydride siloxanes of the general formula
CH ₃ -

O- (SiO ₂ ) _n - (

iO _1.5 ) _m -

CH ₃ ,
where n = 0.8 to 1.2;
m = 0.8 - 1.2,
as an impregnating and finishing agent for wood. 2. A method of obtaining oligotrimethylhydride siloxanes, which consists in carrying out the esterification of a mixture of three chlorosilanes selected from the group consisting of silicon tetrachloride, trichlorosilane, trimethylchlorosilane or a waste product for the production and separation of methylchlorosilanes, including, wt.%:
Silicon tetrachloride 10-60
Trichlorosilane 10 - 40
Trimethylchlorosilane 10 - 60
Other chlorosilanes 3 - 7,
at a molar ratio of silicon tetrachloride, trichlorosilane and trimethylchlorosilane 0.4 - 0.6: 0.4: 0.6: 1, respectively, with an aliphatic alcohol with 1 to 4 carbon atoms at a molar ratio of aliphatic alcohol and ≡Si - Cl 1.0 - 1 , 1: 1, followed by acidolysis of the obtained esters with acetic acid at 30 - 80 ^o C and washing the reaction mass to a neutral reaction.

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