RU2479595C1 - Method of producing fluorine-containing prepolymer having isocyanate groups - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing a fluorine-containing prepolymer having isocyanate groups of general formula:

, which can be used as a modifier of carbo- and hetero-chain polymers, to produce materials having high hydrolytic and thermal stability. Said method involves reaction of a hexamethylene diisocyanate trimer having content of isocyanate groups of 21.8±0.3% with trifluoroacetic acid in the presence of catalytic amounts of di-n-butyltin dilaurate in molar ratio of 1:1:0.003, respectively, in a medium of o-dichlorobenzene at temperature of 70°C, ultrasound frequency 40 kHz for 2 hours.

EFFECT: obtaining a fluorine-containing prepolymer having isocyanate groups using a method which is characterised by homogeneity of the solution of starting reagents, selectivity of formation of the prepolymer, avoiding the need to use auxiliary ingredients and additives, and fewer secondary processes.

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Description

The invention relates to the field of polymer chemistry and can be used as a modifier of homo-and hetero-chain polymers, to obtain materials with high hydrolytic and thermal stability.

A known method of producing fluorine-containing isocyanates, based on heating at 90-130 ° C of azides of aliphatic perfluorodicarboxylic acids in toluene or xylene (Knunyants I.L., Krasusskaya M.P., Deltsova D.P. - Izv. AN SSSR. Ser. Chem., 1966, 1110; Fluorine-containing polyamides and polyurethanes / B.F. Malichenko. - Kiev: Naukova Dumka, 1977, p. 61):

(CF ₂ CF ₂ CON ₃ ) ₂ → (CF ₂ CF ₂ NCO) ₂

The disadvantages of the method used are the inaccessibility and instability of azides, as well as multiple adverse reactions when they are heated (formation of benzimidazolone derivatives, destruction upon reaching the melting temperature).

Another well-known method for producing fluorine-containing aliphatic isocyanates is the heating of the corresponding fluorinated dimethylurethane with phosphorus pentoxide (Fluorine-containing polyamides and polyurethanes / B.F. Malichenko. - Kiev: Naukova Dumka, 1977, p. 61-67):

CH ₃ OCONHCH ₂ (CF ₂ ) ₄ CH ₂ NHOOCH ₃ → OCNCH ₂ (CF ₂ ) ₄ CH ₂ NCO

The disadvantages of this method are multiple adverse reactions and low solubility of the starting solvent reagents.

A known method for producing fluorine-containing diisocyanates by fluorination of trichloromethylphenylenediisocyanates with antimony trifluoride and attaching difluorophosgene to nitriles according to the scheme (Application of Germany No. 2133467, 1973; RZHKhim., 1974, 21N 205; polyurethanes / B.F. Malichenko. - Kiev: Naukova Dumka, 1977, p.67):

R (CN) _n + CF ₂ O → R (CF ₂ NCO) _n

The disadvantages of this method are the high toxicity of difluorophosgene and antimony trifluoride, as well as multiple adverse reactions that occur during the formation of isocyanate.

A known method for producing fluorine-containing isocyanates, based on heating at 90-130 ° C azides of aromatic carboxylic acids in toluene or xylene (US Patent No. 3511870, 1970; RZhKhim., 1971, 7H 666; Malichenko BF Fluorine-containing polyamides and polyurethanes / B.F. Malichenko. - Kiev: Naukova Dumka, 1977, p. 61-67):

The disadvantages of the method used are the inaccessibility and instability of azides, as well as multiple adverse reactions when they are heated (formation of benzimidazolone derivatives, destruction upon reaching the melting temperature).

Another known method for producing fluorinated aromatic isocyanates is the phosgenation of amines, for example 1,4-bis (4-aminophenoxy) benzene, in chlorobenzene for 4 hours with a yield of the final product of 94.8% (German Patent No. 3615723, class C07C 119 / 048, 1986):

The substituents (R ₁ and R _{2 are the} same or different, take the meaning of hydrogen or a methyl group) located in the ortho position to the isocyanate group are able to shield it, significantly reducing the reactivity of the compound and making it difficult to purposefully use the isocyanate as a monomer or polymer modifier.

A known method for producing 1,4-bis- (4-isocyanatophenoxy) tetrafluorobenzene, which consists in phosgenation of the corresponding diamine in nitrobenzene at a temperature of 125-130 ° C for 20 hours (Patent of Ukraine 2074176, IPC С07С 265/12, C08G 18/02, C08G 18/76, publ. 02.27.1997):

The disadvantages of this method are the elevated temperature and long reaction time, which contribute to the formation of by-products of the polymerization of isocyanates in the environment of nitrobenzene.

Known works on the reactions of diisocyanates with hydroxyl-containing compounds (alcohols, carboxylic acids and their derivatives), leading under appropriate conditions (with a molar ratio of reactants 1: 1) to the formation of prepolymers (Saunders J. X. Chemistry of polyurethanes / J.X. Saunders, K.K. Frish. - M .: Chemistry, 1968. - P.91-93):

As a rule, various carboxylic acids are used in these transformations: aliphatic (formic, cyanacetic, trichloroacetic, acrylic and methacrylic acids) and aromatic (benzoic acid and its substituted).

The disadvantages of this method are to obtain a difficult-to-separate mixture of reaction products, including mixed anhydrides, substituted ureas and carbanilides, which complicates the targeted synthesis of prepolymers.

A known method of dehydrofluorination, which allows you to switch from aromatic carbamyl fluoride to the corresponding isocyanate (French Patent 2257378, IPC ⁷ C07C 265/12, C07C 263/04, publ. 27.07.2005). The specified method is that the carbamyl fluoride is subjected to heating in the temperature range of 80-150 ° C in a solvent.

The disadvantages of this method are the low solubility of carbamyl fluoride in a solvent and restrictions on the use of reagents that can be mixed with hydrogen fluoride.

A method for producing cycloaliphatic and aromatic prepolymers of the general formula R (NCO) _n is to heat an amine-containing educt with phosgene in the gas phase in a tubular reactor (German Patent 2387637, IPC C07C 263/10, C07C 265/14, B01J 10/00).

The disadvantages of the method include the wide distribution of the resulting macro- and polyisocyanates by the content of isocyanate groups and the difficulty of separating the resulting mixture of phosgenation products into fractions.

The method of producing macroisocyanates without the use of toxic phosgene includes thermal decomposition in the presence of an aromatic hydroxy compound of carbamic acid esters (Japanese Patent 2434849, IPC C07C 263/04, C07C 265/14, publ. 11/27/2011):

R (NHCOOR ^/ ) _a → R (NCO) _a + aR ^/ OH

The disadvantage of this method of producing isocyanates is the formation of a large hardly separated mixture of reaction products.

A known method for producing fluorine-containing prepolymers by reacting diisocyanates of different chemical structures (isophorondiisocyanate, toluene diisocyanate, 4,4 ^/ -dicyclohexylmethanediisocyanate) with fluorinated oligoesters (bifunctional derivatives of simple perfluoropoly ethersulfonyl ethers at 40 ° C) under 40 ° C conditions catalysis by amines and salts of tetravalent tin (Mashlyakovsky L.N. Synthesis of macrodiisocyanates based on fluorinated diols. Part 1 Kinet the interaction of fluorinated diols with cycloaliphatic and aromatic diisocyanates / L.N. Mashlyakovsky, E.V. Khomko, K. Tonelli // Paints and varnishes and their application. - 2002. - No. 4. - P.8-16). Used fluorinated oligoetherdiols had the following structure (n = 1-2):

HO-CH ₂ CF ₂ O (CF ₂ CF ₂ O) _p (CH ₂ O) _q CF ₂ CH ₂ -OH (product Z-DOL) H (OCH ₂ CH ₂ ) _n OCH ₂ CF ₂ O (CF ₂ CF ₂ O) _p (CH ₂ O) _q CF ₂ CH ₂ O (CH ₂ CH ₂ O) _n H (product Z-DOL TX)

The disadvantages of this method of preparing prepolymers include the limited solubility of oligomeric fluorinated diols, which impedes the preparation of a homogeneous solution, as well as their polymolecularity (these diols include carboxyl groups in addition to hydroxyl groups). Such facts can lead to the appearance of a large number of side processes, which complicates the targeted synthesis of prepolymers.

A known method of producing prepolymers with terminal isocyanate groups, representing urethane, containing the adduct of diphenylmethane diisocyanate (or its oligomers) and polyether polyol

(Application for invention of the USA 99119594, IPC ⁷ C08G 18/10, C08G 18/48, C08G 18/76, publ. 07.27.2001). The resulting prepolymers have an equivalent weight of 2500-7000.

The disadvantages of this method are the wide distribution in the resulting prepolymer of the content of isocyanate groups and equivalent weight, as well as the incorrect determination of the isocyanate index in the presence of significant amounts of water (2-8 parts by weight) and chain extenders in the mixture of reaction products causing amines to form, followed by structuring macromolecular system.

A known method for producing fluorine-containing prepolymers with isocyanate groups by the reaction of aromatic polyisocyanate with polyfluorinated alcohols under the conditions of catalysis with tin di-n-butyldylaurinate and copper diacetate-di-ε-caprolactamate at a temperature of 25-60 ° C in the absence of solvent (Rakhimova N.A. Reaction features polyisocyanate with polyfluorinated alcohols / N.A. Rakhimova, S.V. Kudashev // Izv. Volgograd State Technical University. Series "Chemistry and Technology of Organoelement Monomers and Polymer Materials. Vol. 8: interuniversity collection of scientific articles / VolgSTU. - Volgograd, 20 11. - No. 2. - S.133-140).

The disadvantage of this method is the possibility of chemical bonding of the amide groups of the catalyst (diacetate-di-ε-caprolactamate of copper) with the isocyanate groups of the polyisocyanate with the formation of macrostructures including catalyst fragments, as well as products of the opening of the ε-caprolactam cycle. Moreover, an increase in the molecular weight of polyfluorinated alcohol helps to reduce its solubility in isocyanate.

Known prepolymer obtained on the basis of 4,4 ^/ -diphenylmethane diisocyanate and polytetramethylene ether glycol with a molecular weight of 1950 with a molar ratio of OH: NCO groups equal to 1: 2, which is used for the synthesis of phosphorus-containing polyurethanes (RF Patent No. 2275388, IPC C08G 18/38, C08G 18/46, C08G 18/10, publ. 04/27/2006).

The disadvantages of the method of obtaining the specified prepolymer are its wide polymolecularity, which in some cases prevents the production of polymeric materials with a given set of properties, as well as the absence of a separation stage for unreacted starting compounds.

A known method of producing blocked polyisocyanates used to obtain adhesive varnishes, paints, adhesives and elastomers in the form of hot drying systems for coating substrates of wood, metals, minerals, concrete products, textiles, glass or plastics, and also as a hardener for polyol as one component (German Patent No. 2365599, IPC C08G 18/80, C08G 18/10, C09D 175/04, published on 08.27.2009). These blocked polyisocyanates are obtained by reacting polyisocyanates with secondary amines and hydrophilizing agents of a cationic, anionic and / or nonionic nature:

The disadvantages of this method are multiple adverse reactions, as well as the use in the synthesis of blocked polyisocyanates of water, which causes the formation of amines with the subsequent structuring of the macromolecular system.

A known method of producing a prepolymer with terminal isocyanate groups, characterized by an NCO number in the range of 5-30 wt.% And representing the reaction product of an excess of diphenylmethane diisocyanate containing at least 80 wt.% Of 4,4'-diphenylmethane diisocyanate and polyoxyethylene polyoxypropylene polyol, characterized by an average molecular weight in the range of 2000-10000 (US Patent No. 2320676, IPC C08G 18/10, C08G 18/48, publ. 03/27/2008).

The disadvantages of the method of obtaining the specified prepolymer are its wide polymolecularity, which prevents, in some cases, the production of polymeric materials with desired physical and mechanical properties, as well as the absence of a separation stage for unreacted starting compounds.

Objective: to develop a technologically advanced method for producing a fluorine-containing prepolymer with isocyanate groups with multifunctional properties.

The technical result of the proposed method is the possibility of obtaining a fluorine-containing prepolymer with isocyanate groups in a technological way, characterized by the homogeneity of the solution of the starting reagents, the selectivity of the formation of the prepolymer and the absence of the need for auxiliary ingredients and additives (extenders, crosslinkers), as well as a decrease in the proportion of side processes.

The technical result set in the method for producing a fluorine-containing prepolymer with isocyanate groups of the general formula:

is achieved by reacting a triameric hexamethylene diisocyanate with a content of isocyanate groups of 21.8 ± 0.3% with trifluoroacetic acid in the presence of catalytic amounts of tin di-n-butyldylaurinate at a molar ratio of reactants of 1: 1: 0.003, respectively, in an environment of o-dichlorobenzene at a temperature of 70 ° C, an ultrasound frequency of 40 kHz for 2 hours

The advantages of the method for producing a fluorine-containing prepolymer with isocyanate groups are the good solubility of the starting reagents in o-dichlorobenzene, a decrease in the proportion of by-products, an increase in the degree of conversion of the reagents, which allows the use of the obtained fluorine-based prepolymers as intermediates for the additional introduction of functional groups that provide the required set of polymer properties and operational characteristics materials (Tiger R.P. Polymerization of isocyanates / R.P. Tiger, L.I. Sarynina, S.G. Enteli // Russian Chemical -. T. XLI -. Vyp.9 -. S.1672-1695).

As a diisocyanate, an industrially produced trimer of hexamethylene diisocyanate (the proportion of trimer is 99.85% by weight) with a content of isocyanate groups of 21.8 ± 0.3% was used.

As a fluorine-modifying agent, trifluoroacetic acid of the qualification “Ch.D.A.” was used.

As an organotin catalyst, tin di-n-butyldylaurinate (TU 6-02-818-78) was used in the form of 0.3% of the mass. solution in o-dichlorobenzene.

The solvent used was o-dichlorobenzene of qualification “Ch.D.A.”

The temperature for obtaining a fluorine-containing prepolymer with isocyanate groups of 70 ° C is optimal, since its increase above 70 ° C contributes to an increase in the proportion of resinous compounds, which complicates the isolation and purification of the reaction product. In turn, lowering the temperature to less than 70 ° C reduces the yield of the prepolymer and makes it difficult to separate it from the starting trimer of hexamethylene diisocyanate.

The molar ratio of tin hexamethylene diisocyanate, trifluoroacetic acid and tin di-n-butyldylaurinate, is 1: 1: 0.003, because the stoichiometric composition is violated with a decrease or, conversely, with an increase in the content of the first two components, which makes it difficult to isolate and identification of reaction products. An increase in the content of tin di-n-butyldylaurinate in the reaction mixture of more than 0.003 mol contributes to partial inhibition of the reaction, and a decrease in the amount of catalyst leads to a decrease in the degree of conversion of trifluoroacetic acid.

The reaction for producing a fluorine-containing prepolymer with isocyanate groups at an ultrasound frequency of 40 kHz in a medium of o-dichlorobenzene promotes homogenization of the solution. An increase in the frequency of ultrasound above 40 kHz or, conversely, a decrease does not have a positive effect on increasing the degree of conversion of trifluoroacetic acid.

The reaction time of the trimer of hexamethylene diisocyanate with trifluoroacetic acid in the presence of catalytic amounts of tin di-n-butyldylaurinate is also optimal, since reducing the reaction time to less than 2 hours helps to reduce the degree of conversion of trifluoroacetic acid. Increasing the reaction time over 2 hours contributes to a side reaction of allophanate formation.

The claimed method is as follows.

A solvent (o-dichlorobenzene), a hexamethylene diisocyanate trimer with an isocyanate content of 21.8 ± 0.3%, trifluoroacetic acid and catalytic amounts of tin di-n-butyldylaurinate are placed in the flask, heated to 70 ° C and incubated for 2 hours at an ultrasound frequency of 40 kHz, then the fluorine-containing prepolymer with isocyanate groups is separated, washed and dried.

The method for producing a fluorine-containing prepolymer with isocyanate groups by reacting a triamer of hexamethylene diisocyanate with a content of isocyanate groups of 21.8 ± 0.3% with trifluoroacetic acid in the presence of catalytic amounts of tin di-n-butyldylaurinate and in the environment of o-dichlorobenzene is illustrated by the following example.

Example. In a glass flask with a reflux condenser equipped with a calcium chloride tube, 40 ml of o-dichlorobenzene, 1 g (0.002 mol) of trimer of hexamethylene diisocyanate with the content of isocyanate groups of 21.8 ± 0.3%, 0.23 g (0.002 mol) of trifluoroacetic acid are placed and 0.06 ml (0.003 mol) of tin di-n-butyldylaurinate are added dropwise in the form of 0.5% by weight. solution in o-dichlorobenzene. The flask was thermostated at a temperature of 70 ° C for 2 hours at an ultrasound frequency of 40 kHz. The product is washed with n-hexane, dried over anhydrous calcium chloride and stored in sealed ampoules. The degree of conversion of trifluoroacetic acid is 54.6%. The content of isocyanate groups in the resulting prepolymer 15.3-17.1% of the mass.

Fluorine-containing prepolymer with isocyanate groups. The liquid is a dull white color. Found: N 11.45-12.11%, F 24.10-24.18. IR spectrum, ν, cm ^-1 : 3480 (ν _NH ), 2990-2981 (ν _CH ), 2265.4 (ν _NCO ), 1780 (ν _{C = O} , amide), 1525 (amide I), 1512 ( amide II), 1431 (amide III), 1120-1011 (CF). ¹ H NMR spectrum, (CCl ₄ ), δ, ppm: 6.81 s (C (O) N H ), 3.51 m (C H ₂ -NCO, C H -NCO), 3.18 m (C H -NHC (O), C H ₂ -NHC (O)), 1.26-1.55 m (6H, (CH ₂ ) ₃ ). ¹³ C NMR spectrum (DMSO-d ₆ ), δ, ppm: 161.72 (> C = O, amide), 116.83-117.34 ( C F ₃ ), 124.02 (N C O ), 25.18-44.15 ( C H ₂ , C H).

IR spectra of substances were recorded on a Nicolet-6700 IR Fourier spectrometer and a Specord-M82 spectrometer.

NMR spectra ( ¹ H and ¹³ C) of the substances were recorded on a Varian Mercury Plus instrument (operating frequency 300 MHz, internal standard tetramethylsilane).

In control samples, it was found that the concentration of isocyanate groups of the trimer of hexamethylene diisocyanate in a solution of o-dichlorobenzene without trifluoroacetic acid after heating to 70 ° C for 2 h at an ultrasound frequency of 40 kHz does not change. Therefore, the possible side interaction of the isocyanate groups with residual moisture is not significant in these conditions.

The content of isocyanate groups was determined by titration of a weighed portion of the prepolymer with dibutylamine in acetone according to a known method (Avvakumova NI Workshop on the chemistry and physics of polymers / N.I. Avvakumova [et al.] // Edited by V.F. Kurenkov. - M .: Chemistry, 1995 .-- 256 p.).

Thus, a technological method has been developed for the preparation of a fluorine-containing prepolymer with isocyanate groups by reacting a trimer of hexamethylene diisocyanate with a content of isocyanate groups of 21.8 ± 0.3% with trifluoroacetic acid in the presence of catalytic amounts of tin di-butyldylaurinate and in the environment of an o-dichlorobenzene solution initial reagents, selectivity of the formation of the prepolymer, no need to use auxiliary ingredients and additives (extenders, crosslinkers), as well as smart decreasing the proportion of side processes (allophanate formation).

Claims (1)

A method of obtaining a fluorine-containing prepolymer with isocyanate groups of the General formula

consisting in the interaction of the trimer of hexamethylene diisocyanate with a content of isocyanate groups of 21.8 ± 0.3% with trifluoroacetic acid in the presence of catalytic amounts of tin di-n-butyldylaurinate at a molar ratio of reactants 1: 1: 0.003, respectively, in a medium of o - dichlorobenzene at a temperature of 70 ° C, an ultrasound frequency of 40 kHz for 2 hours