WO2008090153A2

WO2008090153A2 - Method for producing homopolymers and copolymers of vinylphosphonic acid

Info

Publication number: WO2008090153A2
Application number: PCT/EP2008/050705
Authority: WO
Inventors: Rainer Klopsch; Marta Millaruelo; Volker Steinert; Brigitte Voit; Hartmut Komber
Original assignee: Basf Se
Priority date: 2007-01-22
Filing date: 2008-01-22
Publication date: 2008-07-31
Also published as: WO2008090153A3

Abstract

The invention relates to a method for producing homopolymers and copolymers of vinylphosphonic acid having a content of vinylphosphonic acid polymerized into it of at least 30% by weight, based on the overall weight of the homopolymer or copolymer, said method comprising the radical polymerization of a monomer composition that contains, based on the overall amount of the monomers in the monomer composition, a) > 30% by weight of vinylphosphonic acid in the form of its anhydride or an anhydride derivative or in the form of a mixture of vinylphosphonic acid and its anhydride or anhydride derivative (monomer a), and b) < 70% by weight of one or more ethylenically unsaturated monomers that are different from vinylphosphonic acid (monomer b), the polymerization being carried out in a non-aqueous solvent or diluent. The invention also relates to the homopolymers and copolymers that are obtainable by this method.

Description

Process for the preparation of homopolymers and copolymers of vinylphosphonic acid

description

The present invention relates to a process for the preparation of homopolymers and copolymers of vinylphosphonic acid with a copolymerized vinylphosphonic acid content of at least 30% by weight, based on the total weight of the homo- or copolymer. The invention also relates to the homo- and copolymers obtainable by this process.

Polyvinylphosphonic acid (hereinafter also P (PVA)) and copolymers of vinylphosphonic acid are of interest for numerous applications, for example as flame retardants, for the preparation of cation exchange membranes, as additives in coating compositions, as additives for dental cement, as soil improver, as adhesion improver and the like , Due to their high water solubility and biocompatibility, P (PVA) and copolymers with a high content of vinylphosphonic acid are suitable as additives in galenics, for example for the solubilization of active ingredients, as well as for orthopedic applications and for the production of synthetic cartilage and bone material.

However, the preparation of such homo- and copolymers involves a number of problems. Thus, the reactivity of the vinylphosphonic acid under free-radical polymerization conditions is low, and the polymerization times are correspondingly long. In addition, the reaction mixtures obtained in the polymerization generally still contain large amounts of unpolymerized vinylphosphonic acid, which can only be separated off poorly. As a rule, therefore, the products obtained still free vinylphosphonic. Due to the high corrosivity of the vinyl phosphonic acid, these products can only be used to a limited extent. Another problem arises in the copolymerization of vinylphosphonic acid. This is often only partially incorporated into the copolymer, so that form in the radical polymerization considerable amounts of homopolymer and a part of the vinylphosphonic remain in unpolymerized form in the reaction mixture. A further problem in the preparation of homopolymers and copolymers of vinylphosphonic acid is that the polymers obtained usually have only a low molecular weight. This problem occurs in particular when the monomers to be polymerized contain 30% by weight or more of vinylphosphonic acid. The achievable molecular weights (weight average) are then regularly below 30,000 daltons. The polymerization processes for vinylphosphonic acid described in the prior art do not permit the preparation of homo- and copolymers with higher molecular weights. No. 3,297,663 describes a process for preparing homopolymers of vinylphosphonic acid or its salts in which vinylphosphonic acid or a salt of vinylphosphonic acid in an organic solvent which does not dissolve the polymer which forms is polymerized in the presence of a polymerization initiator by the precipitation polymerization method becomes.

EP 114394 describes a process for the radical polymerization of vinylphosphonic acid, in which the vinylphosphonic acid in a protic diluent in the presence of 1, 0 to 5.5 wt .-% of aliphatic peroxide esters, diacyl peroxides and / or aliphatic azo compounds with a certain Decay characteristic polymerized. In this way, the proportion of unreacted vinyl phosphonic acid in the product can be significantly reduced. However, the molecular weights achieved are low. In addition, the residual monomer content is still unsatisfactory.

EP 123297 A2 describes the preparation of crosslinked copolymers, wherein as crosslinking monomer, inter alia, the anhydride of vinylphosphonic acid is proposed. There are described only copolymers with a low content of copolymerized vinylphosphonic.

B. Bingöl et al., Macromolecular Rapid Communications, 2006, 27, pp 1719-1724, describe the radical homopolymerization of a concentrated aqueous vinylphosphonic acid solution having a content of vinyl phosphonic acid of above 65 wt .-%. The authors suggest that under these conditions the vinylphosphonic acid is partly in the form of its anhydride. Due to the high concentration of vinylphosphonic acid, this process is difficult to control. In addition, this method is only suitable for the preparation of homopolymers of vinylphosphonic acid. In addition, the conversions achieved and the molecular weight achieved are unsatisfactory.

The present invention is therefore based on the object to provide a process for the preparation of homo- and copolymers of vinyl phosphonic acid with a content of copolymerized vinyl phosphonic acid of at least 30 wt .-%, which is easy to control and to produce high molecular weight and a low content of unreacted vinylphosphonic acid leads.

It has surprisingly been found that this object is achieved by a radical polymerization process in which one uses a vinylphosphonic acid, which is present at least partially in the form of its anhydride or in the form of an anhydride derivative. Accordingly, this invention relates to a process for the preparation of homopolymers and copolymers of vinylphosphonic acid with a copolymerized vinylphosphonic acid content of more than 30 wt .-%, based on the total weight of the homo- or copolymer, comprising the radical polymerization of a monomer composition which, based on the total amount of monomers in the monomer composition,

a)> 30% by weight of vinylphosphonic acid in the form of its anhydride or of an anhydride derivative of vinylphosphonic acid or in the form of a mixture of vinylphosphonic acid and its anhydride or anhydride derivative (monomer a), and

b) <70% by weight of one or more ethylenically unsaturated monomers other than vinylphosphonic acid (monomer b),

containing, wherein the polymerization is carried out in a non-aqueous solvent or diluent.

The anhydride of the vinylphosphonic acid is understood to mean dimeric and oligomeric compounds of the formula I shown below, in which X 'and X' are OH and n = 1, 2 or 3. Anhydride derivatives are understood as meaning compounds of the formula I in which n has the abovementioned meaning and one or both radicals X and X 'are halogen, for example As chlorine, CrC ₄ -Akoxy, or an acyl radical such as Ci-C4-alkylcarbonyl, z. B. for acetyl, where one of the radicals X or X 'may also be OH. Preference is given to the anhydrides and the acylated anhydrides (ie compounds of the formula I in which one or both radicals X and X 'is an acyl radical, where one of the radicals X or X' can also be OH):

The use of the anhydride or anhydride derivative of the vinylphosphonic acid in the polymerization process according to the invention leads to a significantly increased rate of polymerization in comparison to the pure vinylphosphonic acid. In addition, the content of unreacted vinyl phosphonic acid is significantly lower and is generally not more than 5% by weight, based on the amount of monomer a used. In addition, the molecular weight of the resulting homo- and copolymers is well above 50,000 daltons and is frequently at least 80,000 daltons, and more preferably at least 100,000 daltons, e.g. B. 50,000 to 50,000,000, often 80,000 to 10,000,000 and especially 100,000 to 1,000,000 daltons (weight average, determined by light scattering or viscometry). The molecular weight can also be determined by the relative viscosity which is generally at least 0.6 dL / g and often at least 0.8 dL / g or at least 0.9 dL / g (determined as 1 wt .-% solutions of the respective polymer in water (water-soluble polymers ) or dimethyl sulfoxide or dimethylformamide (water-insoluble polymers)).

The advantages of the invention are surprisingly achieved even at low levels of anhydride or anhydride derivative in the monomers used a. The content of anhydride or anhydride derivative (ie total amount of anhydride and anhydride derivative) is usually at least 5 mol%, often at least 10 mol%, especially at least 20 mol%, preferably at least 30 mol% , particularly preferably at least 40 mol% and very particularly preferably at least 50 mol%, based on the total amount of the monomers a.

The preparation of the anhydride or anhydride derivative of the vinylphosphonic acid can be carried out in a manner known per se, for example by the processes described in SU 174625, EP-A 2733, EP-A 15483, EP-A 32663 and US 2632768 or as described below ,

In general, one will prepare the anhydride or anhydride derivative of the vinylphosphonic acid in a step upstream of the polymerization, for. Example by reacting vinylphosphonic acid with the anhydride of a non-polymerizable carboxylic acid, wherein the anhydride or the acylated anhydride or, depending on the reaction conditions, a mixture of vinylphosphonic acid and the anhydride or acylated anhydride of the vinylphosphonic acid. The product obtained in this case can then be used as monomer (e) a in the polymerization process according to the invention.

Suitable non-polymerizable carboxylic anhydrides are, in particular, the anhydrides of alkanecarboxylic acids having preferably 1 to 6 and in particular 2 to 4 carbon atoms, such as acetic anhydride, propionic anhydride and butyric anhydride. It is also possible to use mixed anhydrides of nonpolymerizable carboxylic acids, in particular mixed anhydrides of alkanecarboxylic acids.

For the preparation of the anhydride or acylated anhydride of the vinylphosphonic acid, the procedure will generally be such that vinylphosphonic acid is reacted with the anhydride of the nonpolymerizable carboxylic acid, for example by reacting vinylphosphonic acid with the anhydride of the nonpolymerizable carboxylic acid, optionally with the addition of a inert organic solvent, mixed. Preferably, it is then subsequently to a temperature above 30 ⁰ C, in particular above 40 ⁰ C, z. B. to a temperature in the range of 40 to 100 ⁰ C to accelerate the formation of the anhydride. However, heating is not required. In general, the anhydride of the non-polymerizable carboxylic acid will be present in an amount of at least 0.3 mol, often in an amount of at least 0.5 mol, e.g. B. in an amount of 0.3 to 10 mol and in particular in an amount of 0.5 to 3 mol and especially in an amount of 0.5 to 1 mol, per mole of vinylphosphonic use. Optionally, it is then possible to remove volatile constituents by distillation, for example by applying a reduced pressure. In this way, a composition is obtained which is generally at least 10% by weight, in particular at least 20% by weight, frequently at least 40% by weight. and especially at least 50% by weight of anhydride or acylated anhydride, based on the total amount of vinylphosphonic acid, anhydride and acylated anhydride. This reaction product can be used immediately without further purification in the polymerization process according to the invention.

The anhydride can also be prepared in situ by, for example, forming the anhydride or the acylated anhydride of the vinylphosphonic acid by reaction of vinylphosphonic acid with the anhydride of a nonpolymerizable carboxylic acid in the polymerization reactor, followed by homo- or copolymerization the monomers a and optionally further monomers. This procedure is particularly useful when carrying out the polymerization in the anhydride of a non-polymerizable carboxylic acid as a solvent.

In the process according to the invention, the monomers a, d. H. the anhydride or anhydride derivative of the vinylphosphonic acid or a mixture of vinylphosphonic acid and its anhydride or anhydride derivative, are polymerized as such. Homopolymers of the vinylphosphonic acid or of the vinylphosphonic acid derivatives are obtained in this way, the latter being able to be converted into the polyvinylphosphonic acid by a simple hydrolytic work-up.

Alternatively, one may copolymerize the monomers a together with comonomers. These are ethylenically unsaturated monomers, in particular monoethylenically unsaturated monomers, which are also referred to below as monomers b.

In the copolymerization, the proportion of monomers a, based on the total amount of the monomers to be polymerized, more than 30 wt .-%, in particular at least 35 wt .-%. Accordingly, the proportion of comonomers (monomers b will not exceed 70% by weight and in particular 65% by weight.

A first preferred embodiment relates to the preparation of homopolymers of vinylphosphonic acid or the preparation of copolymers with a low content of comonomers. In this embodiment, the monomers a constitute 95 to 100% by weight of the total amount of the monomers in the monomer composition to be polymerized. Accordingly, the proportion of monomers b in the monomer composition is not more than 5% by weight. Another, likewise preferred embodiment of the invention relates to the preparation of copolymers of vinylphosphonic acid with a content of copolymerized monomers b of from 5 to 70% by weight, in particular from 10 to 65% by weight. In this embodiment, the monomers a constitute from 30 to 95% by weight, in particular from 35 to 90% by weight, based on the total amount of the monomers in the monomer composition to be polymerized. Accordingly, the monomers b constitute from 5 to 70% by weight, and more preferably from 10 to 65% by weight, based on the total amount of the monomers in the monomer composition.

Suitable monomers b are in principle all monoethylenically unsaturated compounds which, as is known, can be polymerized by free-radical polymerization, but also conjugated diethylenically unsaturated compounds.

The monomers b include hydrophilic monomers, ie those having an increased water solubility of generally at least 50 g / L (monomers b1), but also hydrophobic monomers having a low water solubility of generally less than 50 g / L at 25 ^° C. , hereinafter monomers b2.

Examples of hydrophilic monomers b1 having an increased water solubility of generally at least 50 g / L at 25 ^° C. are:

monoethylenically unsaturated mono- and dicarboxylic acids having 3 to 8 C atoms, such as acrylic acid, methacrylic acid, vinylacetic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid,

Amides of monoethylenically unsaturated carboxylic acids, such as acrylamide or methacrylamide,

Anhydrides monoethylenically unsaturated mono- and dicarboxylic acids having 3 to 8

C atoms, such as maleic anhydride, hydroxyl C 2 -C 4 -alkyl esters of monoethylenically unsaturated mono- or dicarboxylic acids having 3 to 8 C atoms, such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 4-hydroxybutyl methacrylate, - monoethylenically unsaturated sulfonic acids and their salts, eg. Vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid, 2-acrylamidoethanesulfonic acid, 2-methacrylamidoethanesulfonic acid, 2-acryloxyethanesulfonic acid, 2-methacryloxyethanesulfonic acid, 3-acryloxypropanesulfonic acid and 2- Methacryloxypropanesulfonic acid, monoethylenically unsaturated nitriles having 3 to 5 C atoms, such as acrylonitrile and methacrylonitrile, N-vinylheterocycles such as N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylimidazole and monoethylenically unsaturated compounds having at least one P0IV-C 2 -C 4 -alkylene oxide group, for example vinyl and allyl ethers of P0IV-C 2 -C 4 -alkylene glycols or C 1 -C 4 -cyclo-glycols Alkyl-poly-C2-C4-alkylene glycols, esters of monoethylenically unsaturated mono- and dicarboxylic acids having 3 to 8 carbon atoms with poly-C2-C4-alkylene glycols or Ci-Cio-alkyl-poly-C2-C4-alkylene glycols.

In a preferred embodiment, the comonomers b comprise at least 80% by weight, in particular at least 90% by weight, based on the total amount of the monomers b, of at least one such hydrophilic monomer b1 having a water solubility of at least 50 g / l at 25 ^° C has.

Preferred monomers b1 are: monoethylenically unsaturated mono- and dicarboxylic acids having 3 to 8 C atoms, in particular acrylic acid, methacrylic acid and itaconic acid,

Amides of monoethylenically unsaturated carboxylic acids having 3 to 8 C atoms, in particular acrylamide and methacrylamide,

Hydroxy-C 2 -C 4 -alkyl esters of monoethylenically unsaturated monocarboxylic acids having 3 to 8 carbon atoms, in particular hydroxy-C 2 -C 4 -alkyl esters of acrylic acid and of

Methacrylic acid, the abovementioned monoethylenically unsaturated sulfonic acids,

Acrylonitrile and monoethylenically unsaturated compounds having a poly-C 2 -C 4 -alkylene oxide group, in particular the esters of acrylic acid and methacrylic acid with poly-C 2 -C 4 -alkylene oxide

C2-C4-alkylene glycols and the esters of acrylic acid and methacrylic acid with

Ci-Cio-alkyl-poly-C2-C4-alkylene glycols.

Examples of hydrophobic monomers b2 having a limited water solubility of usually not more than 50 g / L are:

vinyl aromatic monomers such as styrene, α-methylstyrene;

Ester monoethylenically unsaturated Cs-Cs monocarboxylic acids with

C 1 -C 20 -alkanols, C 1 -C -cycloalkanols, phenyl-C 1 -C 4 -alkanols or phenoxy-C 1 -C 4 -alkanols, for example, esters of acrylic acid with C 1 -C 20 -alkanols, such as

Methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, lauryl acrylate and stearyl acrylate, esters of acrylic acid with Cs-do cycloalkanols such as cyclohexyl acrylate, esters of acrylic acid with phenyl-Ci C 4 -alkanols such as benzyl acrylate, 2-phenylethyl acrylate and 1-phenylethyl acrylate, esters of acrylic acid with phenoxy

C 1 -C 4 -alkanols, such as 2-phenoxyethyl acrylate, esters of methacrylic acid with C 1 -C 20 -alkanols, preferably C 1 -C 10 -alkanols, such as methyl methacrylate, ethyl methacrylate, acrylate, n-butyl methacrylate, 2-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, decyl methacrylate, lauryl methacrylate and stearyl methacrylate, esters of methacrylic acid with Cs-do cycloalkanols such as cyclohexyl methacrylate, esters of methacrylic acid with phenyl-Ci-C4 alkanols such as benzyl methacrylate, 2-phenylethyl methacrylate and 1-phenylethyl methacrylate, and esters of methacrylic acid with phenoxy-C 1 -C 4 alkanols such as 2-phenoxyethyl methacrylate;

Diesters monoethylenically unsaturated C4-Cs-dicarboxylic acids with C1-C20 alkanols such as diesters of maleic acid or fumaric acid with C1-C20 alkanols, eg. Dimethyl maleate, diethyl maleate, di-n-butyl maleate, dimethyl fumarate, diethyl fumarate and di-n-butyl fumarate;

C 1 -C 20 -alkylamides and di-C 1 -C 20 -alkylamides monoethylenically unsaturated C 3 -C 5 -monocarboxylic acids, in particular the C 1 -C 20 -alkylamides and di-C 1 -C 20 -alkylamides of acrylic acid and of methacrylic acid, eg. B. and vinyl esters of aliphatic carboxylic acids having 1 to 20 carbon atoms, for. Vinyl acetate, vinyl propionate, vinyl butyrate, vinyl hexanoate, vinyl laurate and vinyl stearate; C 2 -C 10 -olefins such as ethylene, propene, 1-butene, 2-butene, isobutene, 1-hexene, 1-octene, diisobutene, 1-decene, 1-dodecene; conjugated diolefins such as butadiene and isoprene, and - halogenovinyl compounds such as chloroethene (vinyl chloride), 1, 1-dichloroethene (vinylidene chloride), fluoroethene, 1, 1-difluoroethene and tetrafluoroethene.

In another preferred embodiment, the comonomers b comprise at least 80% by weight, in particular at least 90% by weight, based on the total amount of the monomers b, of at least one such hydrophobic monomer b2 having a water solubility of less than 50 g / L at 25 ⁰ C has. Examples of preferred monomers b2 are:

vinyl aromatic monomers, especially styrene; Esters of acrylic acid with C 1 -C 20 -alkanols such as methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, lauryl acrylate and stearyl acrylate, esters of acrylic acid with Cs-Cio Cycloalkanols such as cyclohexyl acrylate, esters of acrylic acid with phenyl-Ci-C4-alkanols such as benzyl acrylate, 2-phenylethyl acrylate and 1-phenylethyl acrylate, esters of acrylic acid with phenoxy-Ci-C4-alkanols such

2-phenoxyethyl acrylate, esters of methacrylic acid with C 1 -C 20 -alkanols, preferably C 1 -C 10 -alkanols, such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, decyl methacrylate, lauryl methacrylate and stearyl methacrylate, esters of methacrylic acid with

Cs-Cio-cycloalkanols such as cyclohexyl methacrylate, esters of methacrylic acid with phenyl-Ci-C4-alkanols such as benzyl methacrylate, 2-phenylethyl methacrylate and 1-phenylethyl methacrylate, and esters of methacrylic acid with phenoxy-Ci-C4-alkanols such as 2-phenoxyethyl methacrylate; Vinyl esters of aliphatic carboxylic acids having 1 to 20 carbon atoms, for. Vinyl acetate, vinyl propionate, vinyl butyrate, vinyl hexanoate, vinyl laurate and vinyl stearate; C2-Cio-olefins such as ethylene, propene, 1-butene, 2-butene, isobutene, 1-hexene, 1-octene, diisobutene, 1-decene; and conjugated diolefins such as butadiene and isoprene.

In addition, it may be expedient to increase the molecular weight of the polymers, the polymerization of the monomers in the presence of small amounts of polyethylenically unsaturated monomers with z. B. 2, 3 or 4 polymerizable double bonds perform (crosslinker). Examples thereof are diesters and triesters of ethylenically unsaturated carboxylic acids, in particular the bis- and tris-acrylates of diols or polyols having 3 or more OH groups, eg. As the bisacrylates and the bis methacrylates of ethylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol or polyethylene glycols. If desired, such crosslinkers are used in an amount of generally 0.01 to 10% by weight, based on the total amount of monomers to be polymerized.

According to the invention, the polymerization process is carried out in a non-aqueous solvent or diluent as the polymerization medium. In other words, the polymerization is carried out in a solvent or diluent in the sense of a solution or precipitation polymerization which contains no or only small amounts of water. Based on the total volume of the polymerization mixture, the amount of water is preferably not more than 2% by weight, often not more than 1% by weight, especially not more than 0.5% by weight and especially not more than 0.1 wt .-%. Typically, the amount of water, based on the monomers a, is not more than 10% by weight, frequently not more than 5% by weight, in particular not more than 2% by weight and especially not more than 1% by weight. ,

Suitable solvents or diluents are in particular those in which the monomers to be polymerized are soluble. It is also possible to polymerize in organic solvents in which monomers are not soluble. The polymerization is then carried out as an oil-in-oil emulsion or suspension polymerization wherein, depending on the proportions of polymer and organic solvent, the monomers form the coherent phase or preferably the disperse phase.

Preferred solvents and diluents are aprotic organic solvents and non-polymerizable aliphatic carboxylic acids having preferably 1 to 4 carbon atoms such as formic acid, acetic acid and propionic acid and mixtures thereof with aprotic organic solvents. In the case of precipitation polymerization, it is an organic solvent or diluent in which the copolymer is insoluble. In the case of solution polymerization, it is typically an organic solvent in which the copolymer is soluble.

Suitable solvents include in particular aliphatic and cycloaliphatic hydrocarbons and halogenated hydrocarbons such as hexane, heptane, cyclohexane, dichloromethane, dichloroethane, aromatic hydrocarbons and aromatic halogenated hydrocarbons such as benzene, toluene, xylene, chlorobenzene, dichlorobenzenes, the abovementioned anhydrides of aliphatic, non-polymerizable carboxylic acids such as acetoanhydride , C 1 -C 6 -alkyl esters and C 3 -C 6 -cycloalkyl esters of aliphatic monocarboxylic acids having 1 to 4 carbon atoms, such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl propionate, ethyl propionate, propyl propionate, ethyl formate, butyl formate, cyclohexyl acetate and The like, N, N-di-C 1 -C 4 -alkylamides of aliphatic C 1 -C 4 -carboxylic acids, such as N, N-dimethylformamide, N, N-

Dimethylacetamide, N-C 1 -C 4 -alkyl lactams, such as N-methylpyrrolidone, N-ethylpyrrolidone, di-C 1 -C 4 sulfoxides, such as dimethyl sulfoxide, alicyclic and cyclic ketones having 3 to 8 C atoms, such as methyl ethyl ketone, acetone and cyclohexanone, di-ci C 4 -alkyl ethers and cyclic ethers, such as diethyl ether, methyl tert-butyl ether, dioxane and tetrahydrofuran, and also mixtures of the abovementioned aprotic solvents. Also suitable are non-polymerizable aliphatic carboxylic acids having 1 to 4 carbon atoms such as formic acid, acetic acid and propionic acid and mixtures thereof with the abovementioned aprotic organic solvents.

In general, the organic solvent will be such that the monomers to be polymerized, based on the total amount of monomer plus solvent, in the range of 10 to 65 wt .-%, in particular in the range of 20 to 60 wt .-% lies. In a solution polymerization, accordingly, polymer solutions having solids contents in the range from 10 to 80% by weight and in particular from 20 to 60% by weight are obtained.

The inventive radical polymerization of the monomer composition containing at least 30 wt .-% of the monomers a, can be carried out by conventional methods of radical homo- or copolymerization. As a rule, for this purpose, the monomer composition containing the monomers a and optionally other monomers will polymerize under reaction conditions in which radicals form.

The formation of the radicals is generally carried out by using a so-called polymerization initiator, ie a compound which forms radicals on decomposition, which can be initiated thermally or photochemically. Suitable polymerization initiators include organic azo compounds, organic peroxides and hydroperoxides, inorganic peroxides and so-called redox initiators. The organic peroxide compounds include, for example, acetyl peroxide, benzoyl peroxide, lauroyl peroxide, tert-butyl peroxy-isobutyrate, caproyl peroxide. In addition to hydrogen peroxide, the hydroperoxides also include organic hydroperoxides such as cumene hydroperoxide, tert-butyl hydroperoxide, tert-amyl hydroperoxide and the like. The azo compounds include, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 1, 1 'Azobis (1-cyclohexanecarbonitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (N, N'-dimethyleneisobutyroamidine), 2,2'-azobis (2-methylpropioamidine), N- (3-hydroxy-1,1-bis-hydroxymethylpropyl) -2- [1- (3-hydroxy-1,1-bis-hydroxymethyl-propylcarbamoyl) -1-methyl-ethylazo] -2-methyl-propionamide; N- (1-ethyl-3-hydroxypropyl) -2- [1- (1-ethyl-3-hydroxypropylcarbamoyl) -1-methyl-ethylazo] -2-methyl-propionamide. The inorganic peroxides include peroxodisulfuric acid and its salts, such as ammonium, sodium and potassium peroxodisulfate. Redox initiator system is understood to mean initiator systems which comprise an oxidizing agent, for example a salt of peroxodisulfuric acid, hydrogen peroxide or an organic peroxide such as tert-butyl hydroperoxide and a reducing agent. As reducing agents, they preferably contain a sulfur compound, which is selected in particular from sodium hydrogen sulfite, sodium hydroxymethanesulfinate and the bisulfite adduct to acetone. Further suitable reducing agents are phosphorus-containing compounds such as phosphorous acid, hypophosphites and phosphinates, as well as hydrazine or hydrazine hydrate and ascorbic acid. Furthermore, redox initiator systems can contain additions of small amounts of redox metal salts, such as iron salts, vanadium salts, copper salts, chromium salts or manganese salts, for example the redox initiator system ascorbic acid / iron (II) sulfate / sodium peroxodisulfate. Particularly preferred initiators for the polymerization process according to the invention are azo compounds, especially azobisisobutyronitrile (AIBN). In the polymerization process according to the invention, these polymerization initiators are generally used in an amount of 0.01 to 5 wt .-%, in particular in an amount of 0.1 to 3 wt .-%, based on the monomers to be polymerized.

For polymerization, the usual polymerization techniques can be used. Here are in particular a batch process in which the main amount, ie at least 60 wt .-%, in particular at least 80 wt .-% and often the total amount of the monomers to be polymerized are placed in the polymerization vessel, and the monomer feed, wherein the Main amount of the monomers to be polymerized, often at least 60 wt .-%, in particular at least 80% by weight and especially at least 90 wt .-% be added in the course of the polymerization in the polymerization. For reasons of practicability, the polymerization is often carried out as a monomer feed with larger batches. The polymerization initiator can be introduced into the polymerization vessel or added during the polymerization reaction. Frequently, the procedure is to add at least part of the initiator, preferably at least 50% by weight and in particular at least 80% by weight, of the polymerization initiator in the course of the polymerization reaction.

In particular, it has been proven, a small portion of the monomers, for. B. 0.1 to 20 wt .-%, based on the total amount of the monomers to be polymerized, optionally together with a partial amount or the total amount of polymerization onsinitiator, and to submit a part or the total amount of the solvent or diluent in the polymerization vessel, to start the polymerization, for example by heating the polymerization mixture, and then adding the remaining amount of the monomers and, if necessary, the remaining amount of polymerization initiator and solvent in the course of the polymerization.

The polymerization temperatures customarily used for the polymerization, depending on the initiator system chosen, are generally in the range from 20 to 180 ^° C., in particular in the range from 40 to 130 ^° C. and especially in the range from 50 to 120 ^° C.

The polymerization pressure is of minor importance and can be in the range of atmospheric pressure or slight negative pressure, for. B.> 800 mbar or at overpressure, z. B. to 10 bar, with higher or lower pressures can also be applied.

The polymerization time will usually not exceed 10 hours and is often in the range of 1 to 8 hours.

The polymerization process according to the invention can be carried out in the reactors customary for free-radical polymerization, for example stirred tanks, in particular those with agitated wall stirring, including stirred tank cascades and tubular reactors which optionally have dynamic and / or static mixing elements. The reactors generally have one or more devices for supplying the starting materials and devices for removing the products and, if appropriate, means for supplying and removing the heat of reaction and, if appropriate, means for controlling and / or controlling the reaction parameters pressure, temperature, conversion, etc. The reactors can be operated batchwise or continuously.

After completion of the polymerization, the polymerization mixture can be worked up in the usual way. In the case of a precipitation polymerization, for example, the polymer can be filtered off. Volatile components, for example solvents, can also be removed by distillation. In the case of a solution poly- Merisation can also bring about a precipitation of the resulting polymer, for example by adding an organic solvent in which the polymer is insoluble. Optionally, the resulting polymer is degassed to remove further volatiles.

Furthermore, the resulting polymer can be subjected to a hydrolytic work-up in order to hydrolyze optionally present anhydride groups or acylated groups in the copolymerized vinylphosphonic acid. The hydrolysis can be carried out in a simple manner by treatment with water or dilute aqueous acids such as dilute aqueous hydrochloric acid, sulfuric acid or trifluoromethanesulfonic acid, or bases such as sodium or potassium hydroxide.

Depending on the monomer composition selected, the polymers obtained according to the invention can be used in a variety of ways. Due to the use of the monomers a, the polymers according to the invention, unlike the homopolymers and copolymers of the vinylphosphonic acid known from the prior art, have only small amounts of unpolymerized vinylphosphonic acid after the polymerization reaction, which are typically less than 5% by weight. , in particular less than 2 wt .-%, based on the total amount of monomers used a. Since vinylphosphonic acid can generally not be removed from the resulting polymers or can only be removed with great difficulty, the process according to the invention leads overall to homopolymers and copolymers of vinylphosphonic acid with lower residual monomer contents. Therefore, the homo- and copolymers of vinylphosphonic available according to the invention are particularly suitable for a variety of applications.

The following examples serve to further illustrate the invention and not by way of limitation.

I. Analytics

The ³¹ P NMR spectra were recorded using a Bruker DRX 500 NMR spectrometer.

Relative viscosities were recorded using an Ubbelohde viscometer at 25 ^° C. using capillaries 0a and 0c. 1% strength by weight solutions of the respective polymer in 0.5 N aqueous NaCl solution (homopolymers) or dimethyl sulfoxide (copolymers) were used, which were filtered before the measurement. Examination of the molecular weight by light scattering was carried out using a Sica 50 apparatus using a laser having a wavelength of 632 nm at an angle of 15 ° to 145 °.

II. Preparation of the anhydride of the vinylphosphonic acid

In a reaction vessel was added 7.3 g of acetic anhydride and 11, 38 g of vinylphosphonic acid mixed with stirring and the mixture was heated to 60 ⁰ C. Then removed one by volatile products vaporize in vacuo at 60 ⁰ C until a final pressure of <10 ^'4 mm was reached. The product thus obtained contained 43.1 mole% vinylphosphonic acid, 52.7 mole% vinylphosphonic Anhydride (compound I with n = 1 and R = R '= H) and 4.2 mol% vinylphosphonic acid dianhydride (compound I with n = 2 and R = R' = H).

III. Polymerization

Example 1: homopolymer of vinylphosphonic acid

8.25 g of vinylphosphonic acid and 12.38 g of acetic anhydride and 224.8 mg of azobisisobutyronitrile (AIBN) were placed in a glass vessel. The reaction vessel was charged with nitrogen and the mixture was degassed at least 3 times and each time charged with nitrogen to remove traces of oxygen. At this time, the mixture began to cloud, indicating the onset of polymerization. The mixture was heated to 60 ⁰ C and the temperature for 5 h at. Acetic acid was added and the precipitated polymer was filtered. The polymer was dissolved in water and precipitated by addition of acetic acid. This procedure was repeated twice. The polymer was filtered off and dried for 16 h at 60 ⁰ C in vacuo. In this way, the polymer was obtained in a yield of 95%. The relative viscosity of the polymer was 1.0 dL / g. The light scattering molecular weight was 51300 daltons (weight average).

Example 2: Copolymer of vinylphosphonic acid and n-butyl acrylate in a molar ratio of 1: 1

0.5 g of the mixture of vinylphosphonic acid and vinylphosphonic anhydride described under II. Was added to a reaction vessel together with 0.38 g of n-butyl acrylate, 19.6 mg of AIBN and 1.02 g of tetrahydrofuran. The reaction vessel was charged with nitrogen and the mixture was degassed at least 3 times and each time charged with nitrogen to remove traces of oxygen. At this time, the mixture began to cloud, indicating the onset of polymerization. The polymerization mixture was stirred for 16 hours overnight. In this way a milky liquid was obtained which was precipitated with hexane. The solid was filtered off, dissolved in dichloromethane and precipitated again in hexane. This procedure was repeated. The product was subsequently dried in vacuo at 60 ^° C. for 14 hours. The conversion, based on the monomers used, was 93%. The residual monomer content after the first reprecipitation was less than 7%. The relative viscosity of the product obtained after the 2nd tumble was 1.22 dL / g.

Example 3: Copolymer of vinylphosphonic acid and acrylic acid in the molar ratio 3: 7

In a glass jar, 2.48 g of vinylphosphonic acid, 3.74 g of acrylic acid and 12.38 g of acetic anhydride and 224.8 mg of azobisisobutyronitrile (AIBN) were charged. The mixture was polymerized and worked up analogously to Example 1.

Comparative Example 1

As described for Example 1, vinylphosphonic acid was polymerized in water at a monomer concentration of 43% by weight and worked up. Instead of AIBN, an equimolar amount of 2,2'-azobis (2-methylpropioamidine) was used. The conversion of vinylphosphonic acid was 79%, the viscosity of the product obtained was 0.09 dL / g.

Comparative Example 2

As described for Example 1, vinylphosphonic acid was polymerized in water at a monomer concentration of 70% by weight and worked up. Instead of AIBN, an equimolar amount of 2,2'-azobis (2-methylpropioamidine) was used. The conversion of vinylphosphonic acid was 94%, the viscosity of the product obtained was 0.40 dL / g.

Claims

claims

1. A process for the preparation of homo- and copolymers of vinylphosphonic acid with a copolymerized vinylphosphonic acid content of more than 30 wt .-%, based on the total weight of the homo- or copolymer, comprising the radical polymerization of a monomer composition, based on the total amount the monomers in the monomer composition,

a) more than 30 wt .-% vinylphosphonic acid in the form of its anhydride or anhydride derivative or in the form of a mixture of vinylphosphonic acid and its anhydride or anhydride derivative (monomer a), and b) less than 70 wt .-% of one or a plurality of ethylenically unsaturated monomers other than vinylphosphonic acid (monomer b),

2. The method of claim 1, wherein the proportion of anhydride or anhydride derivative of the vinylphosphonic acid is at least 10 mol%, based on the total amount of vinylphosphonic acid and its anhydride or anhydride derivative.

3. The method according to any one of the preceding claims, wherein the solvent or diluent in an amount of 35 to 95 wt .-%, based on the total amount of monomers and solvents used.

4. The method of claim 3, wherein the polymerization is carried out in an organic solvent or diluent which is selected from aprotic organic solvents or diluents and aliphatic carboxylic acids having 1 to 4 carbon atoms.

5. The method according to any one of claims 3 or 4, wherein the polymerization is carried out in an organic solvent containing an anhydride of a non-polymerizable carboxylic acid.

A process according to any one of the preceding claims, wherein the monomers a make up at least 95% by weight of the total amount of monomers in the monomer composition.

7. The method according to any one of claims 1 to 5, wherein the monomers b 5 bis

70 wt .-%, based on the total amount of the monomers in the monomer composition.

8. The method according to any one of the preceding claims, wherein the monomers comprise b to at least 80 wt .-%, based on the total amount of the monomers b, at least one monomer b1 having a water solubility of at least 50 g / l at 25 ⁰ C.

9. The method according to any one of the preceding claims, wherein the monomers b are selected from

monoethylenically unsaturated mono- and dicarboxylic acids having 3 to 8

C-atoms,

Amides of monoethylenically unsaturated carboxylic acids, anhydrides monoethylenically unsaturated mono- and dicarboxylic acids having 3 to 8 carbon atoms, - hydroxyl C2-C4-alkyl esters of monoethylenically unsaturated mono- or dicarboxylic acids having 3 to 8 carbon atoms, monoethylenically unsaturated sulfonic acids and their salts, monoethylenically unsaturated nitriles having from 3 to 5 carbon atoms, N-vinyl heterocycles and - monoethylenically unsaturated compounds having at least one poly-

C2-C4-a I ky I n ox i d -Gru p pe.

10. Homopolymers and copolymers of vinylphosphonic acid with a content of copolymerized vinylphosphonic acid of at least 30% by weight, based on the total weight of the homo- or copolymer, which have a number-average molecular weight of at least 50,000 daltons.

1 1. Homo- and copolymers of vinylphosphonic according to claim 10, obtainable by a method according to any one of claims 1 to 9.

12. Homo- and copolymers of vinylphosphonic according to any one of claims 10 or 1 1, with a residual monomer content below 5 wt .-%, based on the total amount of monomers used a.