WO2008049471A1

WO2008049471A1 - Water-soluble hydroxy-functional, copolymerizable polyalkylene glycol macromonomers, the production and use thereof

Info

Publication number: WO2008049471A1
Application number: PCT/EP2007/005326
Authority: WO
Inventors: Klaus Pöllmann; Anton Strasser; Sieglinde Müller
Original assignee: Clariant International Ltd.
Priority date: 2006-10-23
Filing date: 2007-06-16
Publication date: 2008-05-02
Also published as: DE102006049804A1

Abstract

The present invention relates to a method for the production of water-soluble block alkoxylates of α,ß ethylenically unsaturated monocarboxylic or dicarboxylic acids in that the α,ß ethylenically unsaturated monocarboxylic or dicarboxylic acid, or an alkoxylatable derivative thereof, is initially alkoxylated with 1 to 4 mol of propylene oxide per carboxylic acid group, and subsequent to this propoxylation an additional alkoxylation step is carried out with ethylene oxide, or a mixture of alkylene oxides comprising at least 70 mol % ethylene oxide, such that the cloud point defined according to DIN 53917 of the block alkoxylate obtained is at least 75°C, wherein the alkoxylation steps are carried out in presence of DMC catalysts.

Description

description

Water-soluble hydroxy-functional, copolymerizable polyalkylene glycol macromonomers, their preparation and use

The present invention relates to a process for the preparation of water-soluble Ω-hydroxy-polyalkylene glycol block copolymers which α-permanently have an unsaturated conjugated ester group, in particular of Ω-hydroxy-methacryloyl or Ω-hydroxy-α-acryloyl-polyalkylene glycol block copolymers and their use as copolymerizable Macromonomers for the emulsification, dispersion and steric stabilization of polymers in aqueous systems.

Polyalkylene glycols are usually industrially produced by anionic, alkali-catalyzed, ring-opening polymerization of epoxides (ethylene oxide, propylene oxide, butylene oxide) under high pressure and high temperature (see Ulimann Encyclopedia of Industrial Chemistry 5th ed VCH, ISBN 3-527-20100-9). With alcohols R'-OH as initiator, such as with methanol, arise so very specific according to equation 1 α-methoxy-Ω-hydroxy polyalkylene glycols

N iNaaOυHti ^R I

UH

R ¹ - OH + n H ₂ C-CHR R IX ^ ^* O 7n Equation 1

With carboxylic acids as initiator, a similar reaction takes place according to Equation 2.

^R equation 2

However, the resulting esters are subject in the alkaline reaction medium running parallel to the ring-opening polymerization permanent hydrolysis and transesterification reaction according to equation 3, which is a product mixture of α-Ω-dihydroxy-polyalkylene glycols, α-Ω-di-esters and the target product (compound ) leads.

Polyalkylene glycol macromonomers are those polyalkylene glycols which, in addition to the polyether chain, contain a reactive, copolymerizable, terminal double bond. They are used for the production of so-called comb polymers with polyalkylene glycol side groups (DE-A-100 17 667) or as reactive emulsifiers in emulsion polymerization (EP-A-1 531 933). However, the Ω-hydroxy-α-allyloxy or Ω-hydroxy-α-vinyloxy-functional polyalkylene glycol macromonomers described there have the disadvantage that they can not be used as hydroxy-functional macromonomers due to the unfavorable copolymerization tendency with many common comonomers , More generally usable and thus substantially more advantageous are Ω-hydroxy-functional polyalkylene glycol macromonomers which have in the α-position the ester group of a conjugated unsaturated acid, in particular Ω-hydroxy-functional -α-methacryloyl or α-acryloyl-polyalkylene glycol macromonomers. Conjugated unsaturated carboxylic acids and esters are understood to mean compounds having a C =C double bond in the ct, β-position to the carbon atom of the carbonyl group, which therefore contain the following structural element:

However, the preparation of such Ω-hydroxy functional polyalkylene glycol macromonomers in pure form, having the α, β-position ester of a conjugated unsaturated acid, is difficult for two reasons.

First, due to those described in Equation 3

Transesterification reaction such macromonomers purely not directly accessible by anionic, alkaline catalyzed, ring-opening polymerization of epoxides. Therefore, various attempts have been made with non-alkaline catalysts to prepare polyalkylene glycol ester macromonomers (Compound 1). In particular, chromium and tin salts (JP-2006-070147, JP-2003073331, CAS AN 103: 215878), boron trifluoride (US 3,689,532) and ZnCo complexes (US 6,034,208) have been proposed as catalysts for all Polyalkylene glycol macromonomers starting from unsaturated carboxylic acids such as methacrylic acid, acrylic acid or maleic acid (JP-2006-070147). However, either only low molecular weights could be achieved or else the products contained a high proportion of cross-linking diester due to the transesterification reactions taking place in accordance with Equation 3 (Ali, Stover, Macromolecules pp. 5219 ff, VoI 37, 2004).

Second, derivatives of conjugated unsaturated acids, especially the acrylic and methacrylic acid derivatives, have a high propensity for homopolymerization, so that the reactions with the alkylene oxides can only be carried out in the presence of high concentrations of polymerization inhibitors (JP-63284146, US Pat.

JP-2005-281274). The prior art uses phenolic or aminic polymerization inhibitors, for example hydroquinone, methylhydroquinone, tert-butylhydroquinone, benzoquinone, BHA, p-phenylenediamine or phenothiazine. These inhibitors react by their active OH or NH end groups in turn with the epoxides to other unwanted by-products. Often, their inhibitory action is also insufficient to completely prevent the polymerization of the conjugated unsaturated acid / ester group. Therefore, it is obtained in reactions with alkylene oxides Macromonomers contaminated with high molecular weight polymers formed by polymerization on the conjugated unsaturated acid group. Such high polymer impurities are by means of

Gel permeation chromatography (GPC) as components with molecular weights greater than 20000 g / mol to recognize.

EP-A-1 012 203 describes the reaction of propylene oxide and mixtures of propylene oxide and ethylene oxide with conjugated unsaturated carboxylic acids and hydroxy esters in the presence of so-called DMC catalysts (DMC double metal cyanide catalysts).

The use of the DMC catalysts avoids the disadvantages of Equation 3, since the reaction does not proceed in alkaline medium and thus the hydrolysis of the resulting esters is not catalyzed. However, DMC catalysts are industrially used exclusively for the polymerization of propylene oxide or propylene oxide-rich alkylene oxide mixtures with more than 50 mol% of propylene oxide, so that in general only water-insoluble or poorly water-soluble polyalkylene glycols can be prepared (EP-O 992 523 A1). To produce polyalkylene glycol macromonomers having good emulsification and stabilization properties, they must have good water solubility. This is achieved by the fact that the proportion of

Ethylene oxide monomer units at least 70 mol%, ideally at least 80 mol%. The high proportion of ethylene oxide units causes a high cloud point of at least 75 ° C, determined in 1% aqueous solution according to DIN 53917, and thus good water solubility. By contrast, EP-A-1 012 203 describes only α-methacryloyl or α-acryloyl macromonomers prepared with pure propylene oxide monomer units or with a random mixture of ethylene oxide and propylene oxide monomer units with less than 50 mol% of ethylene oxide. Such macromonomers have too low cloud points, that is, too low water solubility, in order to achieve sufficient dispersing and emulsifying properties in aqueous solutions. The preparation of purely ethylene oxide-based macromonomers or the preparation of block copolymers with a predominant proportion of ethylene oxide does not succeed according to EP-A-1 012 203. Another method for producing α-methacryloyl or α-acryloyl-polyalkylene glycol macromonomers is therefore the more complicated, two-stage process, first of which produces α-methoxy-Ω-hydroxy-polyalkylene glycols (M-PEGs) and these by esterification with acrylic acid or methacrylic acid in to convert the α-methoxy-Ω-methacryloyl-polyalkylene glycol esters (WO-A-00/012 577, EP-A-0 965 605) (equation 4)

H ₃ C-OH ⁿ H ₂

Equation 4

However, these α-methoxy-Ω-methacryloyl-polyalkylene glycol macromonomers no longer contain any free hydroxy groups and therefore also have less favorable solubility in water and poorer emulsifying properties and are no longer accessible to further reactions owing to the terminal non-reactive Ω-methoxy group.

The object of the present invention was therefore to provide a process for the preparation of readily water-soluble Ω-hydroxyl-functional polyalkylene glycol macromonomers which carry in α-position the structural unit of a conjugated, unsaturated carboxylic acid ester, in particular of readily water-soluble Ω-hydroxy-α-methacryloyl- or Ω-hydroxy-α-acryloyl-polyalkylene glycols, in which the hydrolysis and transesterification according to Equation 3 does not take place, so that pure linear Ω-hydroxy-α- (meth) acryloyl-polyalkylene glycols having an ethylene oxide content of at least 70 molar % arise. In particular, it was an object of the present invention to produce readily water-soluble linear Ω-hydroxy-α- (meth) acryloyl-polyalkylene glycol block copolymers with long polyethylene oxide blocks in this way. It has surprisingly been found that, in contrast to the descriptions in EP-A-1 012 203 and EP-AO 992 523, the preparation of readily water-soluble Ω-hydroxy-α-methacryloyl or Ω-hydroxy-α-acryloyl polyalkylene glycol macromonomers with DMC catalysts is possible. In the preparation of macromonomers having an ethylene oxide content of more than 70 mol% in the presence of a DMC catalyst and of polymerization inhibitors, one starts from conjugated unsaturated acids or conjugated unsaturated hydroxyalkyl esters. The polymerization of the alkylene oxide takes place in two stages, resulting in block copolymers. In the first step, the conjugated unsaturated acids or conjugated hydroxyalkyl esters are reacted in the presence of DMC catalyst and polymerization inhibitor with one to four units of propylene oxide, followed by polymerizing a polyether block having a high ethylene oxide content. As a result, based on the macromonomer molecule, the proportion of polyethylene oxide groups can be increased to more than 70 mol% and thus the water solubility and the cloud point of the macromonomers can be increased.

The invention thus provides a process for the preparation of water-soluble block alkoxylates α, ß-ethylenically unsaturated mono- or dicarboxylic acids by the α, ß-ethylenically unsaturated mono- or

Dicarboxylic acid or an alkoxylatable derivative thereof is first alkoxylated with 1 to 4 moles of propylene oxide per carboxylic acid group, and after this propoxylation a further alkoxylation with ethylene oxide or a mixture of alkylene oxides containing at least 70 mol% of ethylene oxide is carried out, so that according to DIN 53917 certain cloud point of the obtained block alkoxylate is at least at 75 ° C, wherein the alkoxylations are carried out in the presence of DMC catalysts.

The invention preferably provides a process for the preparation of the compounds of the formulas 2, 3, 4 or 5. The preferred process according to the invention comprises a two-stage reaction of the corresponding conjugated α, β-ethylenically unsaturated acids or conjugated α, β-ethylenically unsaturated hydroxyalkyl esters or Hydroxyalkylethoxy and Hydroxyalkylpropoxyester with first 1 to 4 moles of propylene oxide in stage 1 and then ethylene oxide or a mixture of at least 70 mol% of ethylene oxide and propylene oxide in stage 2 catalyzed by a DMC catalyst.

It is further preferred to work in the presence of polymerization inhibitors.

The compounds of formulas 2, 3, 4 and 5 are

Ver ^bi n ^d un ^{g 2)}

^(V he ^bi n ^d un ^{g 3)}

(Compound 4)

(Compound 5)

where k is a number from 1 to 4, n is a number from 1 to 3,

R, R ¹ independently of one another are H or methyl, A is C ₂ - to C ₃ -alkylene, with at least 70 mol% of C ₂ -alkylene, and m is a number from 7 to 500.

(AO) _n may stand for pure polyethylene oxide groups or polyethylene oxide-propylene oxide groups in random arrangement with at least 70 mol% of ethylene oxide.

Reactive derivatives of α, ß-ethylenically unsaturated carboxylic acids are in particular their esters, especially their hydroxyalkyl esters.

Suitable conjugated α, β-unsaturated acids are in particular acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid. Suitable conjugated, unsaturated hydroxyalkyl esters or hydroxyalkylethoxy and hydroxyalkylpropoxy esters are, in particular, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate,

Diethylene glycol monomethacrylate, diethylene glycol monoacrylic acid ester, dipropylene glycol monomethacrylate, dipropylene glycol monoacrylic acid ester, triethylene glycol monomethacrylate, triethylene glycol monoacrylic acid ester, tripropylene glycol monomethacrylate, tripropylene glycol monoacrylic acid ester.

As the polymerization inhibitors, there can be used 2,2,6,6-tetramethylpiperidine-1-oxyl or 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl or other known polymerization inhibitors which inhibit the formation of high polymers by polymerization of the conjugated ones unsaturated acid / ester group in the starting materials and the copolymerizable macromonomers during their production by addition of the alkylene oxides at technically interesting reaction temperatures of 80 - 13O ⁰ C effectively prevent.

The reaction according to the invention of the conjugated unsaturated acids or reactive derivatives, such as conjugated unsaturated hydroxyalkyl esters with alkylene oxides, has to be carried out in the presence of so-called DMC catalysts (double-unsaturated). Metal cyanide catalysts) take place. These catalysts have for example the general formula Zn ₃ [Co (CN) _6] ₂ 'xZnCl _2' yH2θ ^"z glyme with x = 0.2 to 3, y = 1 to 10 and z = 0.5 to 10, as in EP-B-0 555 053. Suitable DMC catalysts are also known in the literature with other complexing ligands. Their preparation and composition are described inter alia in EP-A-1 244 519, EP-A-0 761 708, EP-A-654 302 and EP-A-1 276 563. In particular, the DMC catalysts described in Example 2 of EP-A-1 276 563 are suitable.

The alkylene oxides are metered in a two-stage manner to obtain di- or triblock copolymers with different statistical distribution of the alkylene oxide units in the blocks. All block copolymers have in common that directly to the conjugated α.ß-ethylenically unsaturated carboxylic acid or the conjugated α, ß-ethylenically unsaturated hydroxyalkyl ester or hydroxyalkylethoxy or hydroxyalkylpropoxy ester is first added 1 to 4 MoJ propylene oxide, and then a block ethylene oxide units or randomly mixed Alkylene oxide units having an ethylene oxide content of at least 70 mol% follows. The reaction of the conjugated α, ß-ethylenically unsaturated carboxylic acid or its reactive derivatives and the alkylene oxides, optionally in the presence of polymerization inhibitors, under the usual reaction conditions of a technical, DMC-catalyzed alkoxylation, ie in the temperature range 80-150 ⁰ C preferably 100th -130 ⁰ C and pressures between 2 and 20 bar under nitrogen, optionally in the presence of inert, aprotic solvents such as toluene, xylene or THF.

Crucial for the production of high-quality water-soluble macromonomers in the process according to the invention is the alkoxylation with 1 to 4 moles of propylene oxide per mole of α, ß-ethylenically unsaturated carboxylic acid or its reactive derivatives before the subsequent alkoxylation with ethylene oxide or a mixture of alkylene oxides with at least 70 mol% ethylene oxide. The molecular weight of the reaction products of the invention such as Ω-hydroxy-α-methacryloyl or Ω-hydroxy-α-acryloyl-polyalkylene glycol macromonomers or mixtures thereof with the polymerization inhibitors can by determining the OH number (according to DIN 53240 determination of the number average Mn) and determined by GPC analysis with PEG calibration (determination of the molecular weight distribution). The molecular weight is generally between 500 and 10,000 g / mol, preferably between 750 and 7000 g / mol. The ratio of conjugated unsaturated carboxylic acid to propylene oxide, ethylene oxide units and hydroxyl end groups in the macromonomer can be determined by NMR spectroscopy. The water solubility of the reaction products according to the invention can be determined by determining the cloud point in accordance with DIN 53917 in 1% aqueous solution.

The water-soluble reaction products obtained according to the invention, in particular those of the formulas 2, 3, 4 or 5, can with a variety of radically polymerizable monomers such as styrene, vinyl acetate, acrylic acid, methacrylic acid and their alkyl esters in substance and aqueous solution by using conventional initiators of free-radical polymerization be copolymerized. The resulting comb polymers with polyalkylene side chains are sterically stabilized by the polyalkylene glycol side chains and thus form stable aqueous polymer dispersions.

The invention and applications thereof will now be further explained by way of examples.

Example 1 :

A 1 l pressure reactor is charged with 0.625 mol (90 g) of hydroxypropyl methacrylate and 0.045 g of 2,2,6,6-tetramethylpiperidine-1-oxyl and 0.045 g of the DMC catalyst described in EP-A-1 276 563. The mixture is heated to 110 ^° C. under nitrogen and, at a pressure of about 3 bar, an amount of 72.5 g of propylene oxide is metered in so that the heat of reaction formed can be removed. After the reaction of the propylene oxide recognizable by the pressure drop 560 g of ethylene oxide is metered again so that the resulting reaction heat can be dissipated. After Abreaction recognizable by the pressure drop to the outlet pressure, the product is analyzed by means of OH number titration, NMR spectroscopy and GPC molecular weight determination.

It is thus a methacrylic ester (PO) ₃ (EO) ₂ o-OH block copolymer formed. The cloud point according to DIN 53917 in 1% aqueous solution was more than 95 ° C.

Example 2:

A 1 l pressure reactor is charged with 0.625 mol (90 g) of hydroxypropyl methacrylate and 0.045 g of 2,2,6,6-tetramethylpiperidine-1-oxyl and 0.045 g of the DMC catalyst described in EP-A-1 276 563. The mixture is heated to 120 ^° C. under nitrogen and, at a pressure of about 3 bar, an amount of 72.5 g of propylene oxide is metered in so that the resulting

Heat of reaction can be dissipated. After the reaction of the propylene oxide visible from the pressure drop 560 g of ethylene oxide is metered again so that the resulting heat of reaction can be dissipated. After Abreaktion recognizable by the pressure drop to the outlet pressure, the product by OH number titration, NMR spectroscopy and GPC molecular weight determination is analyzed.

It is thus a methacrylic ester (PO) ₃ (EO) ₂ o-OH block copolymer formed

High polymer fractions with molar masses> 10000 g / mol, such as would be formed by polymerization of the conjugated double bond of the methacrylic acid group, are absent.

The cloud point according to DIN 53917 in 1% aqueous solution was more than

95 ° C

Example 3:

A 3 l pressure reactor is charged with 1 mol (144 g) of hydroxypropyl methacrylate and 0.05 g of 2,2,6,6-tetramethylpiperidine-i-oxyl and 0.15 g of the DMC catalyst described in EP-A-1 276 563. The mixture is heated to 100 ^° C. under nitrogen and, at a pressure of about 3 bar, an amount of 58 g of propylene oxide is metered in so that the heat of reaction formed can be removed. After the reaction of the propylene oxide recognizable by the pressure drop, 1994 g of ethylene oxide is again metered so that the resulting heat of reaction can be removed. After Abreaktion recognizable by the pressure drop to the outlet pressure, the product by OH number titration, NMR spectroscopy and GPC molecular weight determination is analyzed.

Thus, a methacrylic ester (PO) ₂ (EO) ₃₇ -OH block copolymer has been formed

The cloud point according to DIN 53917 in 1% aqueous solution was more than

95 ° C.

Example 4:

The macromonomer of Example 1 is used as coemulsifier in the emulsion polymerization of n-butyl acrylate, methyl methacrylate and methacrylic acid in aqueous liquor. The in situ forming copolymer of butyl acrylate, methyl methacrylate, methacrylic acid and the product of Example 1 has good emulsion stabilizing properties.

500 ml of deionized water are placed in a glass flask and 15 g of sodium alkyl sulfate, 15 g of 3.75% ammonium peroxodisulfate, 11, 5 g of n-butyl acrylate, 11, added 8 g of methyl methacrylate and 0.48 g of methacrylic acid, stirred and under nitrogen to 8O ⁰ C heated up. Over a period of 4 hours, a monomer emulsion is metered in under nitrogen consisting of 470 ml of water, 16 g of sodium alkylsulfonate, 8 g of the product of Example 1, 440 g of n-butyl acrylate, 440 g of methyl methacrylate, 8.8 g of methacrylic acid and 2.85 G Ammonium peroxodisulfate exists. After complete dosing of the monomer emulsion and post-polymerization of one hour at 80 ° C, the polymer dispersion is cooled and adjusted to a neutral pH.

The in situ forming copolymer of butyl acrylate, methyl methacrylate, methacrylic acid and the product of Example 1 is a stable aqueous polymer dispersion.

Example 5: The macromonomer of Example 2 is used as coemulsifier in the

Emulsion polymerization of a styrene / acrylate dispersion used.

For this purpose, a monomer solution (1) of 332 g ml of deionized water, 4.8 g

Sodium alkyl sulfate, 15 g of the product from Example 2, 3.6 g

Sodium bicarbonate, 216 g of styrene, 300 g of n-butyl acrylate, 144 g of methyl acrylate and 6.6 g of methacrylic acid. Likewise, an initiator solution (2) is off

3.33 g of ammonium peroxodisulfate and 85.5 ml of deionized water.

204 g of deionized water are placed in a 2 liter reaction vessel, 6.6 g of the product from Example 2 are added. Under nitrogen atmosphere and

Stirring, the mixture is heated to 80 ⁰ C, then 22 ml of the initiator solution (2) and 25 ml of the monomer solution are added and so

Emulsion polymerization started. At a reaction temperature of 80 ⁰ C, the remaining monomer emulsion (1) and the initiator solution (2) are metered in over 3 hours under cooling. The mixture is then heated for a further hour and the product is neutralized to pH 6 to 8.

The result is a stable polymer dispersion having a solids content of 50%.

Claims

claims:

1. A process for the preparation of water-soluble block alkoxylates α, ß-ethylenically unsaturated mono- or dicarboxylic acids by the α, ß-ethylenically unsaturated mono- or dicarboxylic acid or an alkoxylatable derivative thereof is first alkoxylated with 1 to 4 moles of propylene oxide per carboxylic acid group, and after this propoxylation a further alkoxylation with ethylene oxide or a mixture of alkylene oxides containing at least 70 mol% ethylene oxide, is carried out, so that the determined according to DIN 53917 cloud point of the Blockalkoxylats obtained is at least 75 ⁰ C, wherein the alkoxylation in the presence of DMC -Catalysts take place.

2. The method of claim 1, wherein the produced water-soluble block alkoxylate is selected from compounds 2, 3, 4 or 5

^(V e ^rbind un ^{g 2)}

< ^{Affiliation 3)}

(Compound 4)

where k is a number from 1 to 4, n is a number from 1 to 3,

R, R ¹ independently of one another are H or methyl,

A is C ₂ - to C ₃ -alkylene, with at least 70 mol% of C ₂ -alkylene, and m is a number from 7 to 500.

3. The method of claim 1 and / or 2, wherein as the conjugated, α, ß-unsaturated acid acrylic acid, methacrylic acid, fumaric acid, maleic acid or itaconic acid are used.

4. The method of claim 1 and / or 2, wherein as a reactive derivative of a conjugated, α, ß-unsaturated acid hydroxyethyl methacrylate,

Hydroxypropyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, diethylene glycol monomethacrylic acid ester, diethylene glycol monoacrylic acid ester, dipropylene glycol monomethacrylate, dipropylene glycol monoacrylic acid ester, triethylene glycol monomethacrylate, triethylene glycol monoacrylic acid ester, tripropylene glycol monomethacrylate, tripropylene glycol monoacrylic acid ester.

5. The method according to one or more of claims 1 to 4, wherein the cloud point of the resulting block alkoxylate is greater than 90 ⁰ C.

6. The method according to one or more of claims 1 to 5, wherein 2,2,6,6-tetramethylpiperidine-i-oxyl or 4-hydroxy-2,2,6, 6-tetramethylpiperidine-1-oxyl be used as a polymerization inhibitor.

7. The method according to one or more of claims 1 to 6, which is carried out in the temperature range of 80 - 150 ⁰ C.

8. The method according to one or more of claims 1 to 7, which is carried out at pressures between 2 and 20 bar under nitrogen.

9. Use of the obtained by the process according to claim 1 to 8 block alkoxylates as copolymerizable emulsifier, additive, emulsifier or co-emulsifier for emulsion stabilization in emulsion or suspension polymerizations.