DE102004047893B3 - Novel polymeric mercapto-terminated polysulfides with ether groups and intermediates for their preparation - Google Patents

Abstract

Mercapto group-containing polymeric polysulfides with additional ether groups are described which can be prepared by reacting formaldehyde with a monomeric dihydroxyalkyl-terminated disulfide, etherifying the OH groups with epichlorohydrin or an alenyl halide, in particular allyl halide, and reacting the resulting ethers with hydrogen sulfide or a dimercaptan. It also describes the corresponding intermediates. The products obtained can be produced with great uniformity, reproducibly and at high reaction rates. DOLLAR A They are particularly suitable for the production of sealants and chemically resistant coatings such. B. insulating glass seals and joint sealing strips and high-quality coatings.

Description

The The invention relates to novel mercapto group-containing polymeric polysulfides and a process for their preparation and intermediates, the polysulfides containing the polymeric mercapto groups can serve.

Mercapto-containing polymers have been known for a long time. So be in the EP 0 171 198 B1 such polymers described. To prepare these substances, a process is used in which an epoxy resin having an epoxy group content of 2 to 6 mol / kg is reacted with a mercapto-terminated polymer having at least two mercaptan groups per molecule and a molecular weight not exceeding 2,000; while a curable liquid block copolymer is obtained.

The there described substances called prepolymers, are stable to viscosity only after a few weeks. Also, the implementation takes relatively long. Furthermore, as far as their uniformity is concerned, these products to be desired.

Also in the US 2,731,437 Mercapto-containing polysulfides are mentioned.

The hitherto known methods have u. a. the disadvantage that they are heavy are controllable, d. H. that it is extremely difficult is to get products that are both of their chemical structure as well as their molecular weight, are uniform. So receives you often use different approaches despite the same reaction conditions corresponding polymers with different molecular weight distribution. Also, the inconsistency, or polydispersity, within the individual approaches quite high.

Also let the speeds with which the individual conversions run, to be desired. The corresponding processes are common highly corrosive and contaminated with high salt load.

It there is still a need for improved polymeric mercapto-containing polysulfides as well as improved manufacturing processes.

task Therefore, it is the object of the invention to have polymeric mercapto groups Polysulfides available to ask, which is a cheaper Have molecular weight distribution (i.e. narrow distribution) targeted with a specific molecular weight can be produced and which are useful as valuable end or intermediate products.

task The invention is also a corresponding manufacturing method to disposal to make that easy and economical as well as possible Low-salt and low-corrosion, working through a high speed of individual reaction steps and distinguished which leads to largely uniform products and that reproducible is working.

task The invention further provides an intermediate product available from which in a simple manner the polymeric mercapto groups containing polysulfides can be obtained.

These Task is solved by a process for the preparation of polymeric mercapto end groups Polysulfides by first Formaldehyde with a monomeric dihydroxyalkyl-terminated disulfide converts to a polymeric hydroxyalkyl-terminated polysulfide, the OH groups etherified with epichlorohydrin or an alkenyl halide and the resulting ether with hydrogen sulfide or a dimercaptan converts to the mercapto-terminated polysulfide, which additional Contains ether moieties.

When Formaldehyde is preferably used paraformaldehyde.

monomers Dihydroxyalkyl disulfides, in particular the so-called dithiodiglycol, are known compounds.

In the context of the invention, however, a dithiodiglycol (also bis (2-hydroxyethyl) disulfide is preferred called), which by a method according to German Patent DE 103 238 39 is obtained. According to the teaching of this patent, which is particularly incorporated herein by reference and incorporated herein by reference, mercaptoethanol is reacted with oxygen or an oxygen-containing gas in the presence of ammonia and / or amines using copper or manganese salts to form dithiodiglycol. A corresponding synthesis is described in Example 1 of DE 103 238 39 described.

The Reaction of formaldehyde and bis (2-hydroxyethyl) disulfide is in itself already known and is for example in the US PS 4,124,645 mentioned.

in the However, the preparation of the present invention is preferred of the hydroxyalkyl-terminated polymer polysulfide by a process carried out, that according to the teaching the one with equal priority deposited German patent application (internal file reference T 634). According to this Process is formaldehyde in particular paraformaldehyde and bishydroxyethyl disulfide reacted in the presence of solid acidic catalysts.

Corresponding the teaching of this patent application, to which particular reference is made here and the disclosure of which is incorporated herein by reference this is a process for the preparation of hydroxyalkyl-terminated polymers Polysulfides by reacting bishydroxyalkyl monomeric polysulfides with Reacting formaldehyde in the presence of acidic catalysts, characterized that the acid catalyst is used in the form of a solid acid and the water and optionally co-used solvent and the catalyst separated from the reaction product.

wobei R' ein aliphatischer Kohlenwasserstoffrest mit der Formel (-CH₂-)_x ist, x = 2 bis 4, und n = 4 bis 50 ist.The reaction according to reaction equation I reproduces the reaction of formaldehyde with dihydroxyalkyl disulfide to give the corresponding hydroxyalkyl-terminated polysulfide. Reaction equation I

wherein R 'is an aliphatic hydrocarbon radical of the formula (-CH ₂ -) _x , x = 2 to 4, and n = 4 to 50.

Preferably, R '= -CH ₂ -CH ₂ -

In In a second process step, the polymer is hydroxyalkyl terminated Polysulfide etherified either with epichlorohydrin or with an alkenyl halide, preferably an allyl halide in particular Allyl chloride.

wobei X ein Halogen, bevorzugt Chlor ist und R' und n die vorstehend angegebenen Werte haben.This step is carried out according to the reaction equations II a and II b. This produces a polymer with terminal double bonds or a polymer with terminal epoxy groups. This reaction is an etherification of the polymeric hydroxyalkyl terminated polysulfide. Reaction equation IIa

wherein X is a halogen, preferably chlorine and R 'and n have the values given above.

n hat den Wert von 4 bis 50 und R' die vorstehend angegebene Bedeutung.The product obtained by etherification in accordance with reaction equation II a, which serves as an intermediate for the preparation of the polymeric mercapto end polysulfides, is a further object of the invention. Reaction equation IIb

n has the value of 4 to 50 and R 'has the meaning given above.

The obtained by the etherification with epichlorohydrin according to reaction equation II b Epoxy-containing polymeric polysulfide is another object the invention. This product serves as an intermediate for production the polymeric mercapto-terminated polysulfides.

It but also as such z. B. together with amines or mercaptans for the production of very high quality sealants and coatings suitable.

wobei R' und n die vorstehend angegebene Bedeutung haben.In a further step, the reaction then takes place to give the end product, ie the polymer having the terminal double bonds or the polymer having the terminal epoxy groups is reacted with hydrogen sulfide or a dimercaptan. These reactions are represented by the reaction equations III a, III b, III c and III d. Reaction equations III a - Reaction with hydrogen sulphide

where R 'and n have the meaning given above.

The Mercapto groups can also be arranged asymmetrically on the polymer, i. at one end of the molecule as a primary, at the other end of the molecule as a secondary Be bound to SH groups.

wobei R'' ein aliphatischer Rest der Formel – (CH₂)_x – ist mit x = 2-4 und R' sowie n die vorstehend angegebene Bedeutung besitzen.Formula A shows the secondary arrangement of the SH groups. The invention includes both the compounds with symmetrical secondary arrangement as indicated under formula A and the symmetrical compounds with primary arrangement of the SH groups as indicated in formula B and the asymmetric arrangements ie with one primary and one secondary arrangement of the SH group ( Markovnikov / anti-Markovnikov). Reaction equation III b - Reaction with a dimercaptan

where R "is an aliphatic radical of the formula - (CH ₂ ) _x - where x = 2-4 and R 'and n have the abovementioned meaning.

Also here we can as in III a arise asymmetric chains.

Reaction equations III c and III d starting from epoxy groups

The reaction product according to reaction equation II b is reacted analogously to III a and III b with hydrogen sulfide or a dimercaptan. Reaction equation III c - Reaction with hydrogen sulfide

Again, the mercapto group can sit on the penultimate or second carbon atom of the chain. Again, asymmetric structures are possible. Reaction equation III d - reaction with dimercaptans

object The invention further comprises ether groups containing mercapto groups polymeric polysulfides according to the formulas A to H and their isomer mixtures, wherein R ', R "and n are the above have meaning indicated.

Except the preferably used allyl halides, with which the etherification carried out will, can according to the inventive method as alkenyl halides also vinyl halides, in particular vinyl chloride be used. When working with vinyl chloride is its volatility and carcinogenicity as well as corrosiveness and inclination to sudden To consider polymerization, special protective measures must therefore be taken to Specialist familiar are.

The Etherification with alkenyl halides is conveniently used a catalyst, in particular a phase transfer catalyst carried out under basic conditions.

The Reaction of the polysulfides with the two double bonds with hydrogen sulfide or alkanedithiols such. B. ethanedithiol is conveniently done under basic and radical conditions. As a catalyst system is preferably a peroxidic compound together with a used organic base. Particularly suitable here are z. B. t-butyl perbenzoate and 1,1,3,3-tetramethylguanidine.

The according to the method according to the invention produced polymeric mercapto-terminated polysulfides are particularly suitable for the production of flexible, corrosion and chemical resistant sealants and coatings. there the polymer is cured by oxidation of the Thiolendguppen.

The inventive method is very simple and economical and extremely environmentally friendly feasible.

The Invention will be explained in more detail with reference to the following examples

example 1

Allyl termination (according to reaction equation II a)

600 g of a hydroxy-terminated polysulfide (M _n = 2300 g / mol) are dissolved in 500 ml of toluene. Thereafter, 84 g of 50% sodium hydroxide solution are suspended therein. Subsequently, a phase transfer catalyst (quaternary ammonium salt, eg 5 g of triethylbutylammonium chloride) is added. 80 g of allyl chloride are then slowly added over one hour at 30 ° C. Thereafter, the reaction mixture is stirred for 3 h at 40 ° C. To complete the reaction is heated to 60 ° C for 8 hours. After cooling the batch, the organic is separated from the aqueous phase. The organic phase is filtered and concentrated on a rotary evaporator. Last traces of solvent are removed in an oil pump vacuum. There are left behind 624 g of a light yellow low-viscosity polymer having a number average molecular weight (M _n ) of 2400 g / mol.

Example 2

Allyl termination (according to reaction equation II a)

600 g of a hydroxy-terminated polysulfide (M _n = 2300 g / mol) are dissolved in 500 ml of toluene and suspended with 84 g of 50% sodium hydroxide solution. Subsequently, the catalyst system (quaternary ammonium salt, eg 5 g of triethylbutylammonium chloride) is added. 126 g of allyl bromide are slowly added dropwise. Thereafter, the reaction mixture is stirred for 3 h at 40 ° C. To complete the reaction is heated to 60 ° C for 8 hours. After cooling the batch, the organic is separated from the aqueous phase. The organic phase is filtered and concentrated on a rotary evaporator. Last traces of solvent are removed in an oil pump vacuum. There are obtained 621 g of a pale yellow low-viscosity polymer having a number average molecular weight (M _n ) of 2500 g / mol.

Example 3

Implementation allyl-terminated Polysulfide with hydrogen sulfide (formula A / B) (according to the reaction equation III a)

2500 g of an allyl-terminated polysulfide (M _n = 2000 g / mol) are dissolved in 2000 ml of toluene and treated with 6 g of triethylamine. Subsequently, hydrogen sulfide is introduced into the solution at room temperature. The temperature of the solution rises to about 40 ° C. The reaction is completed when a gas breakthrough in the downstream wash bottle is observed. In vacuo, the dissolved in the reaction mixture hydrogen sulfide is removed. Subsequently, the batch is filtered and the solvent distilled off. Solvent residues are removed in an oil pump vacuum. 2545 g of a yellow low-viscosity polymer (22 Pa.s) having a number-average molecular weight (M _n ) of 2200 g / mol and an SH content of 2.9% are obtained.

Example 4

Implementation allyl-terminated Polysulfide with ethanedithiol (formula C / D) (according to reaction equation III b)

500 g of an allyl-terminated polysulfide (M _n = 2000 g / mol) are dissolved in 300 ml of toluene and mixed with 60 g of ethanedithiol and homogenized. Subsequently, the catalyst system (5.6 g of t-butyl perbenzoate / 0.28 g of 1,1,3,3-tetramethylguanidine) is added. After stirring for 15 minutes, the reaction mixture is heated to 60 ° C. After 24 hours, the excess ethanedithiol and the solvent are distilled off. Solvent residues are removed in an oil pump vacuum. There are obtained 544 g of a light yellow low-viscosity polymer (19 Pa · s) having a number average molecular weight (M _n ) of 2150 g / mol and an SH content of 3.1%.

Example 5

Reaction hydroxy-terminated Polysulfide with epichlorohydrin (according to reaction equation II b)

6400 g of a hydroxy-terminated polysulfide (M _n = 2000 g / mol) are dissolved in 4000 ml of epichlorohydrin. Subsequently, a phase transfer catalyst (eg 2 g Aliquat 336) is added. The reaction vessel is evacuated to 100 mbar and heated to 40 ° C. A total of 2750 g of 50% sodium hydroxide solution are added within 2 h. After completion of the addition, the batch is slowly heated to 60 ° C. The water of reaction is removed by the boiling epichlorohydrin within 6 h from the reaction mixture (azeotropic distillation). To complete the reaction, the mixture is heated for 2 h at 80 ° C in a vacuum (150 mbar). After cooling, the mixture is filtered and the solvent is distilled off in vacuo. Solvent residues (epichlorohydrin) are removed on a thin-film evaporator. There are 6530 g of a light yellow odorless low-viscosity (26 Pa · s) polymers having a number average molecular weight (M _n ) of 2100 g / mol of.

Example 6

Implementation of epoxy-terminated Polysulfide with hydrogen sulfide (formula E / F) (according to the reaction equation III c)

1500 g of an epoxy-terminated polysulfide (M _n = 2000 g / mol) are dissolved in 2000 ml of toluene and treated with a basic catalyst (10 g of triethylamine). Subsequently, in the solution at Raumtem temperature hydrogen sulfide introduced. The temperature of the solution rises to about 40 ° C. The reaction is completed when a gas breakthrough in the downstream wash bottle is observed (after about 8-10 h). In vacuo, the dissolved in the reaction mixture hydrogen sulfide is removed. Subsequently, the batch is filtered and the solvent distilled off. Solvent residues are removed in an oil pump vacuum.

1600 g of a pale yellow low-viscosity polymer (viscosity 31 Pa.s) having a number-average molecular weight (M _n ) of 2250 g / mol and an SH content of 3.1% are obtained.

Example 7

Implementation of epoxy-terminated Polysulfide with ethanedithiol (formula G / H) (according to reaction equation III d)

100 g of an epoxy-terminated polysulfide (M _n = 2300 g / mol) are dissolved in 150 ml of toluene and treated with 10 g of 1,4-butanedithiol. Subsequently, a basic catalyst (5 g of triethylamine) is added. The reaction mixture is heated to 100 ° C for 6 h. It is then filtered and the solvent removed in vacuo. 115 g of a pale yellow, low-viscosity polymer (viscosity 27 Pa.s) having a number-average molecular weight (M _n ) of 2400 g / mol with a thiol content of 2.8% are obtained.

Claims (10)

A process for the preparation of polysulfides containing polymeric mercapto end groups with ether groups, which comprises first reacting formaldehyde with a monomeric dihydroxyalkyl-terminated disulfide to form a polymeric hydroxyalkyl-terminated polysulfide, etherifying the OH groups with epichlorohydrin or an alkenyl halide, and using hydrogen sulfide or a dimercaptan for the resulting ether Reacting polysulfide having Mercaptoendgruppen. Method according to claim 1, characterized in that that is used as formaldehyde paraformaldehyde. A method according to claim 1 or 2, characterized in that one uses as monomeric dihydroxyalkyl-terminated disulfide Bishydroxyethyldisulfid, which according to a method according to German Patent DE 103 238 39 ie by reacting mercaptoethanol with oxygen or an oxygen-containing gas in the presence of ammonia and / or amines using copper or manganese salts. Method according to one of claims 1 to 3, characterized that the preparation of the polymeric hydroxyalkyl-terminated Polysulfide according to a process according to the German with the same priority deposited patent application (internal file reference: T 634) performs, according to which Formaldehyde, especially paraformaldehyde and bis (2-hydroxyethyl) disulphide be reacted in the presence of solid acidic catalysts. Double bond polysulfides having the chemical formula CH ₂ = CH-CH ₂ -O-R'-SS-R '(-OCH ₂ -O-R'-SS-R') _n -O-CH ₂ -CH = CH ₂ , wherein R 'is an aliphatic hydrocarbon radical of the formula (-CH ₂ -) _x , x = 2-4 and n is 5-50. Epoxy group-containing polysulfides of the chemical formula

where R 'and n have the meaning given above. Polymeric mercapto-terminated polysulfides of the formula CH ₃ -CH (SH) -CH ₂ O-R'-SS-R '(-OCH ₂ OR'SS-R') _n -OCH ₂ -CH (SH) -CH ₃ , where R 'and n have the meaning given above. or the formula HS-CH ₂ CH ₂ CH ₂ -O-R'-SS-R '- (OCH ₂ OR'SSR'-) _n OCH ₂ CH ₂ CH ₂ -SH where R 'and n have the meaning given above. Mercapto-terminated polymeric polysulfides of the chemical formula HS-R''SCH ₂ CH ₂ CH ₂ OR'SSR '(- OCH ₂ OR'SSR') _n -OCH ₂ CH ₂ CH ₂ -SR '' - SH or HS-R''SCH (CH ₃ ) CH ₂ OR'SSR '(- OCH ₂ OR'SSR') _n -OCH ₂ CH (CH ₃ ) SR '' - SH wherein R 'and n have the meaning given above and R''is an aliphatic radical of the formula - (CH ₂ ) _x - with x = 2-4. Mercapto-terminated polymeric polysulfides of the chemical formula HS-CH ₂ CH (OH) CH ₂ OR'SSR '(- OCH ₂ OR'SSR') _n -OCH ₂ CH (OH) -CH ₂ -SH or HS-CH (CH ₂ OH) CH ₂ OR'SSR '(- OCH ₂ OR'SSR') _n -OCH ₂ CH (CH ₂ OH) -SH where R 'and n have the meaning given above. Mercapto-terminated polymeric polysulfides of the chemical formula HS-R''SCH ₂ CH (OH) CH ₂ OR'SSR '(- OCH ₂ OR'SSR') _n -OCH ₂ CH (OH) CH ₂ -SR '' - SH or HS-R''SCH (CH ₂ OH) CH ₂ OR'SSR '(- OCH ₂ OR'SSR') _n -OCH ₂ CH (CH ₂ OH) SR '' - SH wherein R ', R "and n have the meaning given above.