DE3733314A1 - Process for the polymerisation of polar compounds (II) - Google Patents

Abstract

The invention relates to a process for the polymerisation of polar compounds which contain a C = C double bond in the alpha -position to a carbonyl or nitrile group, especially acrylic acid derivatives. The polymerisation is quasi-ionic, is initiated by organometallic compounds of silicon, germanium or tin as initiators together with nucleophilic or electrophilic catalysts and is carried out at temperatures in the range from -100@C to +100@C. The initiators used are silanes, germanes, stannanes, siloxanes, germoxanes or stannoxanes in which at least one metal-bonded hydrocarbonoxy group is present per metal atom.

Description

The invention relates to a method for polymerization of polar compounds that are in the alpha position too a carbonyl or nitrile group is a C = C double bond have, including in particular acrylic acid derivatives understand how esters, nitriles and amides of acrylic acid and methacrylic acid.

Polymeric acid derivatives are being used on an industrial scale mostly produced by radical polymerization, the free radical initiators triggered and comes to a standstill by chain break which two of the radicals formed react with each other. However, polymers with a high molecular weight can do a great deal broad molecular weight distribution can be obtained. Block copolymers with a defined arrangement of the individual blocks cannot be made in this way.

The anionic polymerization of acrylic acid derivatives is also known, that not by radicals but by Initiators forming anions, such as alkali-organic compounds, is triggered and the so-called living  Polymers with active terminal groups leads because a Chain termination by reaction of two charged in the same direction Ions is not possible. The chain termination can be artificial Be brought about, for example by water or Alcohol addition. A disadvantage of this method is that the desired narrow molecular weight distribution only at low Temperatures (down to -80 ° C) and with very pure raw materials can be achieved (cf. US-A 43 51 924).

The polymerization of acrylic acid derivatives is based on a similar basis, which are called "quasi-ionic" has become known. Here the start reaction is carried out certain selected initiators together with nucleophiles or electrophilic catalysts triggered, likewise living polymers are formed. As selected Initiators are silicon, tin and germanium compounds known in which the elements mentioned on oxygen or carbon atoms are attached, such as trimethylsilyl ketene acetals or trimethylsilyl cyanide (cf. US-A 44 14 372, US-A 44 17 034, US-A 45 08 880 and US-A 45 24 196). This procedure can be performed at room temperature and above but also requires raw materials of high purity and also only leads to methacrylic acid derivatives to polymers with the desired narrow molecular weight distribution.

In contrast, initiators of the mercaptosilane type are said to under the conditions of quasi-ionic polymerization mentioned living polymers with narrow molecular weight distribution also when using acrylic acid derivatives as Monomers are obtained (see. DE-A 35 04 168, the US-A Corresponds to 46 26 579).  

According to the state of the art, the quasi ionic polymerization using certain organosilicon compounds as initiators in connection with nucleophilic or electrophilic catalysts made from monomers Acrylic acid derivatives of any kind Polymers with narrow molecular weight distribution are obtained, their average However, molecular weights themselves in general are relatively low.

The object of the invention is a method for polymerization of polar compounds that are in the alpha position too a carbonyl or nitrile group is a C = C double bond have to provide, in which the Polymerization with organometallic compounds as initiators together with nucleophilic or electrophilic catalysts, optionally in the presence of an aprotic solvent is triggered in the entire temperature range of -100 ° C up to + 100 ° C for all kinds of acrylic acid derivatives is applicable and can also deliver polymers that both a high average molecular weight as well have narrow molecular weight distribution.

This task is carried out in the process for the polymerization of mentioned type according to the invention solved in that as Initiators organometallic compounds selected from the Group of silanes, germans, stannanes, siloxanes, germoxanes and stannoxanes are used, the minimum per molecule a silyl, germyl, stannyl and / or siloxanyl, Germoxyl-, Stannoxylgruppe contain, in which each Metal atom at least one metal atom-bound Hydrocarbonoxy group is present.  

As silanes, germans, stannanes are monosilanes, -germans or stannanes of the general formula

R _{4- n} M (OR ′) _n (I)

as well as di- and poly compounds of the general formula

R′O [M (OR ′) ₂] _x [M (R) (OR ′)] _y [M (R) ₂] _z OR ′ (II)

preferred, wherein
M = Si, Ge, Sn;
R = H atoms, alkyl, cycloalkyl, alkenyl, aryl, aralkyl or alkaryl radicals, optionally substituted by fluorine, chlorine, alkoxy / or acyloxy;
R ′ = alkyl, cycloalkyl, aryl, aralkyl, alkaryl or alkenyl radicals with the proviso that the oxygen atom must be bound to an sp³-hybridized carbon atom of the alkenyl radical;
n = 1, 2 or 3;
x, y and z have values from 0 to 500 and the sum of x + y + z must be at least 2.

As siloxanes are those from units of the general formula

preferred, wherein R and R 'have the meaning given above;
c = 0, 1, 2 or 3, on average 0.01 to 2.5;
e = 0, 1, 2 or 3, on average 0.1 to 2.5 and the sum of c + e per unit = at most 3, - as well as the corresponding germanium and tin compounds.

Examples of radicals R in the silanes, siloxanes, germanics, germoxanes, stannanes or stannoxanes used according to the invention, which may be the same or different, are alkyl radicals having 1-18 C atoms, preferably 1-4 C atoms, which are straight-chain or branched can, such as methyl, ethyl, n-propyl, iso-propyl, and n-butyl radicals; Cycloalkyl radicals, such as cyclopentyl and cyclohexyl radicals; Alkenyl radicals with 2-18 carbon atoms, preferably 2-4 carbon atoms, such as vinyl and allyl radicals;
Aryl residues such as phenyl, tolyl, xylyl and naphthyl residues;
and aralkyl radicals, such as the benzyl radical. Because of the easy accessibility, ethyl, vinyl, phenyl and especially methyl radicals are particularly preferred as radicals R.

Examples of radicals R 'are the same as those given for R. with the above Exception for alkenyl residues where the Oxygen atom on an sp³-hybridized carbon atom of the same must be bound, which means that between the metal-bound oxygen atom and the C = C- Double bond of the alkenyl radical without at least one carbon atom Double bond character must be present. That means, that, for example, vinyl residues connected as residues R ' are.

Examples of organometallic materials which can be used according to the invention Compounds are monomeric silanes, such as trimethoxymethylsilane, Trimethoxy-ethylsilane, trimethoxypropylsilane, Trimethoxy-phenylsilane, triethoxy-phenylsilane, Triisopropoxy-propylsilane, dimethoxy-methyl-vinylsilane, Methoxy-dimethyl-vinylsilane and disilanes, such as 1,2-dimethyl 1,1,2,2-tetramethoxy-disilane and methoxytributyltin, Methoxytrimethyltin.  

Examples of siloxanes are solvent-free, low viscous alkyl esters of oligomeric alkyl silicas such as these from units of the average formula

CH₃Si (O) _1.1 (OCH₃) _0.3

with a viscosity of about 30 mm² / s. In general, the ability to initiate increases Silanes and siloxanes used according to the invention in the Sequence:

(R) ₃Si (O-R ′) <(R) ₂Si (O-R ′) ₂ <(R) Si (OR ′) ₃,

and with decreasing size of the rest O-R ′:

O-iPr <O-Et <O-Me.

The used as initiators according to the invention Organometallic compounds are either commercially available Products or they can in a manner known per se getting produced.

For carrying out the polymerization process the organometallic compounds used according to the invention together with nucleophilic or electrophilic catalysts used. Such catalysts are known and described for example in US-A 44 17 034. Have tetrabutylammonium fluoride and tetrabutylammonium cyanide has proven itself particularly well.

The molar ratio of initiator: catalyst is usually in the range from 1000 to 1: 1, preferably in Range from 100 to 10: 1.

The polymerization process itself can vary depending on the selected initiator at temperatures in the range of  -80 ° C to + 100 ° C, preferably in the range of -20 ° C to + 60 ° C and in particular in the range from 0 ° C to + 50 ° C, performed will. The key here is that under exclusion working from moisture, which is usually with the help of an inert gas atmosphere, such as argon or nitrogen, or with dry air. The Polymerization can take place without or in the presence of an aprotic Solvent are carried out, advantageously such be selected in which both the used Monomers as well as initiator and catalyst in the intended Reaction temperature are sufficiently soluble. Examples of such aprotic solvents are Methyl acetate, ethyl acetate, butyl acetate, acetonitrile, toluene, Xylene, N, N-dimethylformamide, N-methylpyrrolidone, tetrahydrofuran, tert-butyl methyl ether and silicone oils, including in particular polydimethylsiloxane oils and polymethylphenylsiloxane oils with viscosities in the range of about 5- 500 mPa · s / 25 ° C are to be understood.

As monomers to be polymerized, as already mentioned, in particular acrylic acid derivatives of any kind are used, such as esters, amides and nitriles of acrylic acid and methacrylic acid. Examples of this are in particular Acrylic acid esters, such as n-butyl acrylate and 2-ethylhexyl acrylic acid; Methacrylic acid esters, such as Methyl methacrylate, ethyl methacrylate, Methacrylic acid n-butyl ester, methacrylic acid cyclohexyl ester, Methacrylic acid dodecyl ester and methacrylic acid tetradecyl ester.

The implementation of the polymerization process can in known discontinuously or continuously be made. The initiator and catalyst are advantageous submitted and the monomers with or without solvent metered in, the good by mechanical movement  Distribution of the monomers supported and by cooling for it can be ensured that the intended temperature of the exothermic reaction is not exceeded.

After the added monomers have been consumed, the polymerization reaction comes to a standstill. in the However, there are living polymers in the reaction vessel, too are still active after consumption of the monomers. These can in a known manner by adding other monomers further polymerized to block copolymers or by addition of chain termination reagents or so-called coupling agents be converted into inactive polymers, such as described in detail in US-A 44 17 034.

With the help of the initiators used according to the invention not just acrylic acid derivatives of any kind in a wide range Temperature range are polymerized quasi-ionically, but predominantly the polymers obtained syndiotactic structure are characterized by a high Molecular weight and a narrow molecular weight distribution out.

The invention is explained in more detail in the following examples. In the following examples, the polymerization reactions each under argon as an inert gas atmosphere or dry air unless otherwise specified is. The solvents used were known Process dried and the monomers by filtration over Alumina cleaned.

The preparation of the anhydrous solution of tetrabutylammonium fluoride in tetrahydrofuran, or toluene, was carried out in  known manner using calcium hydride. The polymeric end products were NMR spectroscopic (1 H-NMR) and gel chromatography (GPC) characterized. Silanes and siloxanes the technical manufacturing were done directly without additional Cleaning used. The chain structure of the obtained Polymers was 60-70% syndiotactic, as by NMR proven. The average molecular weight _n   was determined by GPC in each case.

Example 1

In a solution of 0.41 g (3 mmol) trimethoxymethylsilane and 0.1 mmol (1 ml of a 0.1 M solution in toluene) tetrabutylammonium fluoride in 100 ml of anhydrous toluene with stirring and cooling within 30 min. 92 g (500 mmol) Acrylic acid 2-ethyl-hexyl ester entered so slowly that the reaction temperature did not exceed 40 ° C. To The exothermic reaction was terminated for a further 4 h stirred at room temperature. Then the solvent removed in vacuo and the product at 60 ° C in a high vacuum dried.

Yield: 88 g (95% of theory); highly viscous product; GPC: _n  27,000.

Example 2

In a solution of 0.41 g (3 mmol) trimethoxymethylsilane and 0.1 mmol (1 ml of a 0.1 M solution in toluene) tetrabutylammonium fluoride in 100 ml of anhydrous toluene, 43 g (500 mmol) methyl acrylate with cooling so slowly entered that the reaction temperature did not exceed 40 ° C. After the exothermic reaction had ended  stirred for a further 4 h at room temperature. Then was the product dried in vacuo.

Yield: 31 g (72% of theory); waxy product; GPC: _n   9000.

Example 3

The procedure according to Example 1 was repeated with the Modification that instead of 2-ethyl-hexyl acrylate 26.5 g (500 mmol) of acrylonitrile were polymerized. Yield: 6.5 g (25% of theory); Dec .: 186 ° C.

Example 4

In a solution of 0.4 g (3 mmol) dimethoxy-methyl-vinylsilane and 0.1 mmol (1 ml of a 0.1 M solution in Tetrahydrofuran) tetrabutylammonium fluoride in 100 ml anhydrous toluene was 92 g with cooling and stirring (500 mmol) 2-ethylhexyl acrylate so slowly entered that the reaction temperature + 10 ° C not exceeded. After stirring for a further 5 h at room temperature the solvent is removed in vacuo and the product 60 ° C dried in a high vacuum.

Yield: 92 g (quantitative); highly viscous product; GPC: _n  26,000.

Example 5

The procedure according to Example 4 was repeated with the Modification that 74 g (500 mmol) n-butyl acrylate with 0.72 g (3 mmol) triethoxy-phenylsilane as initiator and 0.25 mmol  Polymerized tetrabutylammonium fluoride as a catalyst were.

Yield: 69.8 g (97% of theory); viscous product; GPC: _n  24,000.

Example 6

The procedure according to Example 4 was repeated with the Modification that 74 g (500 mmol) of tert-butyl acrylate with 0.68 g (5 mmol) trimethoxymethylsilane as initiator and 0.2 mmol of tetrabutylammonium fluoride as a catalyst Temperatures between 0 ° C and + 10 ° C were polymerized.

Yield: 66.9 g (90% of theory); Mp 103 ° C; GPC: _n  55,000.

Example 7

In a solution of 10 g (100 mmol) methyl methacrylate in 30 ml of anhydrous toluene 0.72 g (5 mmol) Trimethoxymethylsilane and 0.2 mmol tetrabutylammonium fluoride (2 ml of a 0.1 M solution in tetrahydrofuran) registered. After 20 min. a strongly exothermic reaction occurred on. After cooling to 20 ° C and with cooling vigorous stirring a further 40 g (400 mmol) methyl methyl acrylate in 50 ml of anhydrous toluene so slowly entered that the reaction temperature is not 20 ° C. exceeded. After standing for a further 2 hours, the Solvent removed in vacuo and the product at 60 ° C in High vacuum dried.  

Yield: 42 g (84% of theory); Mp 264 ° C; GPC: _n  18,000.

Example 8

The procedure according to Example 4 was repeated with the Modification that a mixture of 40 g (400 mmol) acrylic acid ethyl ester and 24 g (100 mmol) acrylic acid dodecyl ester with 0.72 g (5 mmol) trimethoxy-methylsilane as Initiator and 0.4 mmol tetrabutyl ammonium fluoride as Catalyst were polymerized.

Yield: 60 g (94% of theory); highly viscous product.

Example 9

The process according to Example 1 was repeated with the modification that 64 g (500 mmol) n-butyl acrylate with 2 g of a siloxane composed of units of the average formula CH₃Si (O) _1.1 (OCH₃) _0.8 with a viscosity of 30 mm² / s, dissolved in 100 ml of anhydrous toluene as the initiator and 0.25 mmol of tetrabutylammonium fluoride (1 ml of a 0.25 M solution in tetrahydrofuran) were polymerized as a catalyst.

Yield: 56.8 g (86% of theory); viscous product; GPC: _n  22,000.

Example 10

The procedure according to Example 1 was repeated with the Modification that 64 g (500 mmol) of tert-butyl acrylate with 0.58 g (5 mmol) methoxy-dimethyl-vinylsilane as Initiator and 0.2 mmol tetrabutylammonium fluoride as Catalyst were polymerized.  

Yield: 58 g (90.6% of theory); Mp 80 ° C; GPC: _n  22,000.

Example 11

The procedure according to Example 1 was repeated with the Change that 64 g (500 mmol) n-butyl acrylate with 1.6 g (5 mmol) methoxy-tributyltin as initiator, dissolved in 150 ml of anhydrous tert-butyl methyl ester and 0.25 mmol Tetrabutylammonium fluoride (1 ml of a 0.25 M solution in Tetrahydrofuran) were polymerized as a catalyst.

Yield: 32 g (50% of theory) of viscous oil; GPC: _n  6500.

Example 12

The procedure according to Example 1 was repeated with the Modification that 60 g (500 mmol) of tert-butyl acrylate with 1.6 g (5 mmol) methoxy-tributyltin as an initiator in 90 ml of anhydrous tert-butyl methyl ether, and 0.25 mmol Tetrabutylammonium fluoride (1 ml of a 0.25 M solution in Tetrahydrofuran) were polymerized as a catalyst.

Yield: 55.7 g (66% of theory); Mp: 90 ° C; GPC: _n  37,500.

Example 13

The procedure according to Example 1 was repeated with the Modification that 64 g (500 mmol) of tert-butyl acrylate with 1.6 g (5 mmol) methoxy-tributyltin as initiator, dissolved in 100 ml of anhydrous toluene, and 0.25 mmol Tetrabutylammonium fluoride (1 ml of a 0.25 M solution in Tetrahydrofuran) were polymerized as a catalyst.

Yield: 64 g (quantitative); Mp .: 94 ° -96 ° C.

Claims (3)

1. A process for the polymerization of polar compounds which have a C = C double bond in the α position to a carbonyl or nitrile group, in which the polymerization is initiated with organometallic compounds of silicon, germanium and tin as initiators together with nucleophilic or electrophilic catalysts and at temperatures in the range from -100 ° C to + 100 ° C, optionally in the presence of an aprotic solvent, characterized in that organometallic compounds selected from the group consisting of silanes, germanes, stannanes and siloxanes, germoxanes and stannoxanes are used as initiators which contain at least one silyl, germyl, stannyl and / or siloxanyl, germoxanyl, stannoxanyl group per molecule, in which at least one metal-bonded hydrocarbonoxy group is present per metal atom. 2. The method according to claim 1, characterized in that as silanes, germans and stannanes those of the general formula R _{4- n} M (OR ' ) _n and di- and polysilanes-germanes and stannanes of the general formula R'O [M (OR ') ₂] _x [M (R) (OR ′)] _y [M (R) ₂] _z OR ′ (II) can be used, in which
M = Si, Ge or Sn;
R = H atoms, alkyl, cycloalkyl, alkenyl, aryl, aralkyl or alkaryl radicals, optionally substituted by fluorine, chlorine, alkoxy / or acyloxy;
R ′ = alkyl, cycloalkyl, aryl, aralkyl, alkaryl or alkenyl radicals with the proviso that the oxygen atom must be bound to an sp³-hybridized carbon atom of the alkenyl radical;
n = 1, 2 or 3;
x, y and z values from 0 to 500 have the sum of x + y + z must be at least 2. 3. The method according to claim 1, characterized in that as siloxanes from units of the general formula are used, wherein R and R 'have the meaning given above;
c = 0, 1, 2 or 3, on average 0.01 to 2.5;
e = 0, 1, 2 or 3, on average 0.1 to 2.5, and the sum of c + e per unit = at most 3.