Water-soluble copolymer composition with neutral pH

Abstract

The present invention relates to the field of copolymers which are water-soluble or water-dispersible at neutral pH or near-neutral pH, that is to say between 5.5 and 9.5, comprising at least one random copolymer comprising methacrylic acid, butyl acrylate, styrene and a monomer chosen from styrenesulfonic acid or salts thereof, vinylbenzoic acid or salts thereof, 2-acrylamido-2-methanesulfonic acid or salts thereof, N-vinylpyrrolidone, alone or in combination.

Claims

1. A composition comprising a random copolymer, where the random copolymer comprises the following monomers: 1 to 45% by weight of styrene, limits included; 35 to 45% by weight of methacrylic acid, limits included; 15 to 35% by weight of butyl acrylate, limits included; 1 to 45% of a monomer chosen from styrenesulfonic acid or salts thereof, vinylbenzoic acid or salts thereof, 2-acrylamido-2-methanesulfonic acid or salts thereof, N-vinylpyrrolidone, alone or in combination, limits included, wherein the weight % is relative to the total weight of the random copolymer, and wherein the random copolymer has a weight-average molecular weight of between 30,000 and 300,000 g/mol.

2. The composition as claimed in claim 1, wherein the random copolymer is prepared by controlled radical polymerization.

3. The composition as claimed in claim 1, wherein the glass transition temperature of the copolymer as measured by DMA is greater than 60° C.

4. The composition as claimed in claim 2, wherein the polymerization is carried out by RAFT controlled radical polymerization.

5. The composition as claimed in claim 2, wherein the polymerization is carried out by ATRP controlled radical polymerization.

6. The composition as claimed in claim 1, wherein the polymerization is carried out by NMP controlled radical polymerization.

7. The composition as claimed in claim 6, wherein the nitroxide from the NMP is from alkoxyamines derived from the stable radical of formula (1): ##STR00003## wherein R.sub.L has a molar mass of greater than 15.0342 g/mol.

8. The composition as claimed in claim 7, wherein the alkoxyamines are derived from the following stable radicals: N-(tert-butyl)-1-phenyl-2-methylpropyl nitroxide, N-(tert-butyl)-1-(2-naphthyl)-2-methylpropyl nitroxide, N-(tert-butyl)-1-dibenzylphosphono-2,2-dimethylpropyl nitroxide, N-phenyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide, N-phenyl-1-diethylphosphono-1-methylethyl nitroxide, N-(1-phenyl-2-methylpropyl)-1-diethylphosphono-1-methylethyl nitroxide, 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxy, 2,4,6-tri-tert-butylphenoxy nitroxide, N-(tert-butyl)-1-diethylphosphono-2,2-dimethylpropyl nitroxide.

9. The composition as claimed in claim 8, wherein the alkoxyamines are derived from N-(tert-butyl)-1-diethylphosphono-2,2-dimethylpropyl nitroxide.

10. A filament extruded from a composition as claimed in claim 1.

Description

DETAILED DESCRIPTION

(1) The term “water-solubilization or water-dispersibility” is intended to mean a solublization or a dispersibility in an aqueous phase of which the pH is between 5.5 and 9.5, in a temperature range of between 40 and 70° C.

(2) A polymer is said to be “dispersible” if it forms, at a concentration of 5% by weight in a solvent, at 25° C., a stable suspension of fine, generally spherical, particles. The average size of the particles constituting said dispersion is less than 1 μm and, more generally, ranges between 5 and 400 nm, preferably from 10 to 250 nm by weight. These particle sizes are measured by light scattering.

(3) When the solvent is water, the term used is “water-dispersible” polymer.

(4) The copolymers of the invention can be prepared by radical polymerization or by controlled radical polymerization. When it is a question of obtaining a water-soluble or water-dispersible copolymer, the applicant notes, however, that it is preferable to use controlled radical polymerization and that the copolymer thus prepared is more rapidly solubilized or dispersed in an aqueous solution.

(5) To this effect, use may be made of any type of controlled radical polymerization in the context of the invention, such as NMP (“Nitroxide Mediated Polymerization”), RAFT (“Reversible Addition and Fragmentation Transfer”), ATRP (“Atom Transfer Radical Polymerization”), INIFERTER (“Initiator-Transfer-Termination”), RITP (“Reverse Iodine Transfer Polymerization”) or ITP (“Iodine Transfer Polymerization”).

(6) According to a preferred embodiment of the invention, the copolymers are prepared by nitroxide mediated polymerization (NMP).

(7) More particularly, the nitroxides resulting from the alkoxyamines derived from the stable free radical (1) are preferred.

(8) ##STR00001##
wherein the radical R.sub.L has a molar mass of greater than 15.0342 g/mol. The radical R.sub.L may be a halogen atom such as chlorine, bromine or iodine, a saturated or unsaturated, linear, branched or cyclic, hydrocarbon-based group, such as an alkyl or phenyl radical, or an ester group —COOR or an alkoxyl group —OR or a phosphonate group —PO(OR).sub.2, as long as it has a molar mass of greater than 15.0342. The monovalent radical R.sub.L is said to be in the β position relative to the nitrogen atom of the nitroxide radical. The remaining valences of the carbon atom and of the nitrogen atom in formula (1) can be bonded to various radicals, such as a hydrogen atom or a hydrocarbon-based radical, for instance an alkyl, aryl or arylalkyl radical, comprising from 1 to 10 carbon atoms. It is not excluded for the carbon atom and the nitrogen atom in formula (1) to be connected together via a divalent radical, so as to form a ring. Preferably, however, the remaining valences of the carbon atom and of the nitrogen atom of formula (1) are bonded to monovalent radicals. Preferably, the radical R.sub.L has a molar mass of greater than 30 g/mol. The radical R.sub.L may, for example, have a molar mass of between 40 and 450 g/mol. By way of example, the radical R.sub.L may be a radical comprising a phosphoryl group, it being possible for said radical R.sub.L to be represented by the formula:

(9) ##STR00002##
wherein R.sup.1 and R.sup.2, which may be identical or different, may be chosen from alkyl, cycloalkyl, alkoxyl, aryloxyl, aryl, aralkyloxyl, perfluoroalkyl or aralkyl radicals and may comprise from 1 to 20 carbon atoms. R.sup.3 and/or R.sup.4 can also be a halogen atom, such as a chlorine or bromine or fluorine or iodine atom. The radical R.sub.L may also comprise at least one aromatic ring, such as for the phenyl radical or the naphthyl radical, it being possible for said ring to be substituted, for example with an alkyl radical comprising from 1 to 4 carbon atoms.

(10) More particularly, the alkoxyamines derived from the following stable radicals are preferred: N-(tert-butyl)-1-phenyl-2-methylpropyl nitroxide, N-(tert-butyl)-1-(2-naphthyl)-2-methylpropyl nitroxide, N-(tert-butyl)-1-dibenzylphosphono-2,2-dimethylpropyl nitroxide, N-phenyl-1-diethylphosphono-2,2-dimethylpropyl nitroxide, N-phenyl-1-diethylphosphono-1-methylethyl nitroxide, N-(1-phenyl-2-methylpropyl)-1-diethylphosphono-1-methylethyl nitroxide, 4-oxo-2,2,6,6-tetramethyl-1-piperidinyloxy, 2,4,6-tri-tert-butylphenoxy nitroxide, N-(tert-butyl)-1-diethylphosphono-2,2-dimethylpropyl nitroxide.

(11) The alkoxyamines used in controlled radical polymerization must allow good control of the linking of the monomers. Thus, they do not all allow good control of certain monomers. For example, the alkoxyamines derived from TEMPO make it possible to control only a limited number of monomers; the same is true for the alkoxyamines derived from 2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide (TIPNO). On the other hand, other alkoxyamines derived from nitroxides corresponding to formula (1), particularly those derived from nitroxides corresponding to formula (2) and even more particularly those derived from N-(tert-butyl)-1-diethylphosphono-2,2-dimethylpropyl nitroxide, make it possible to broaden the controlled radical polymerization of these monomers to a large number of monomers.

(12) In addition, the alkoxyamine opening temperature also influences the economic factor. The use of low temperatures will be preferred in order to minimize industrial difficulties. The alkoxyamines derived from nitroxides corresponding to formula (1), particularly those derived from nitroxides corresponding to formula (2) and even more particularly those derived from N-(tert-butyl)-1-diethylphosphono-2,2-dimethylpropyl nitroxide, will therefore be preferred to those derived from TEMPO or 2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide (TIPNO).

(13) The weight proportion of the monomers is chosen in the following ranges: styrene, from 1 to 45% by weight, limits included, and preferably from 5 to 30%, limits included; methacrylic acid, from 35 to 45% by weight, limits included, and preferably from 35 to 40%, limits included; butyl acrylate, from 15 to 35% by weight, limits included, and preferably from 20 to 30%, limits included; a monomer chosen from styrenesulfonic acid or salts thereof, vinylbenzoic acid or salts thereof, 2-acrylamido-2-methanesulfonic acid or salts thereof, or N-vinylpyrrolidone, alone or in combination, in proportions of from 1 to 45%, limits included, and preferably from 15 to 45%, limits included.

(14) Preferably, the preferred monomer is styrenesulfonic acid or salts thereof.

(15) The weight-average molecular weight of the water-soluble or water-dispersible copolymers which are a subject of the invention, measured by SEC, is between 30 000 g/mol and 300 000 g per mole, preferably between 70 000 and 170 000 g/mol, and more preferably between 80 000 and 130 000 g/mol.

(16) The dispersity of the water-soluble or water-dispersible copolymers is less than 2.2 and preferably less than 2.

(17) The glass transition temperature (Tg), measured by DMA (dynamic mechanical analysis), of the random copolymer present in the composition which is a subject of the invention is greater than 60° C. and preferably greater than 110° C.

(18) The water-soluble or water-dispersible compositions which are a subject of the invention may contain impact modifiers, whether they are of the random copolymer or block copolymer type, or else core-shell particles, alone or in combination.

(19) The compositions of the invention can be used as dispersing agents for pigments, or else as rheology modifiers in applications such as drilling muds, textile printing pastes, the cosmetics industry, or else the detergents industry, and other coating compositions such as paint, and as an anti-settling and/or suspending agent for coarse mineral or organic fillers in the phytosanitary field, but also the field of three-dimensional printing (or 3D printing) of an object of the FDM (fused deposition molding) type as a sacrificial polymer. In this respect, the compositions of the invention can be formed in the form of an extruded filament, with or without impact modifiers, these extruded filaments also being a subject of the invention.

(20) The invention also relates to the objects obtained by means of the compositions of the invention.

EXAMPLES

(21) The mixture of reagents is the following: Initiator: BlocBuilder® (from Arkema) Styrene (St) (from Aldrich) Methacrylic acid (MAA) (from Aldrich) Sodium styrene sulfonate (from Aldrich) Butyl acrylate (BuA) (from Aldrich) Ethanol (from Aldrich) Initiator: BlocBuilder® (from Arkema) Styrene (St) (from Aldrich) Methacrylic acid (MAA) (from Aldrich) Sodium styrene sulfonate (from Aldrich) Butyl acrylate (BuA) (from Aldrich) Ethanol (from Aldrich) Toluene (from Aldrich) DMSO (dimethyl sulfoxide), (from Aldrich)

(22) TABLE-US-00001 TABLE 1 Control (g) Test 1 invention (g) Initiator 1.7 0.7 Styrene 149. 30.5 Methacrylic acid 200 81.5 Sodium styrene sulfonate 0 30.5 Butyl acrylate 153 61.2 Ethanol 179 41 Toluene 119 41 DMSO 0 313 Reactor temperature 110-118° C. 110-118° C.

(23) All of the reagents and solvents are introduced into a 2 l closed stainless steel reactor, under a nitrogen atmosphere. The mixture is heated for 180 minutes, with stirring at 200 rpm.

(24) The final conversion is 71%. The copolymer of the invention is recovered by precipitation from acetone. For the control copolymer, the residual monomers and solvents are removed in an oven under vacuum at 100° C. In the 2 cases, the residue obtained is dried and then ground in a mortar so as to be used in powder form. The composition of the three copolymers is analyzed by .sup.1H NMR and gives the following results as % by weight, table 2:

(25) TABLE-US-00002 TABLE 2 Control Test 1 invention Styrene 37 19 Methacrylic acid 40 36 Sodium styrene sulfonate 20 Butyl acrylate 23 25
Dissolution Tests

(26) The copolymers obtained are heated to a temperature of 160° C. under a compression press so as to form a pellet 2.5 cm in diameter and 1 mm thick. The pellets are then placed in a beaker, with stirring, in water at pH 7 at a temperature of 60° C.

(27) The samples are periodically removed and weighed in order to evaluate the weight loss linked to the dissolution of the polymer. The tests are carried out at a pH of 7 at 60° C.; table 1:

(28) TABLE-US-00003 TABLE 3 Time % Weight loss pH 7 (min) Test 1 Invention Control 0 0 0 10 0 0 15 100 0 20 100 0 30 100 0 40 100 3

(29) FIG. 1 shows the dissolution of the control copolymer and of the copolymer of the invention (test 1) at pH=7 and 60° C.

(30) It is noted that the copolymers prepared using the four monomers Abu/STY/AMA/sodium styrene sulfonate (Invention) dissolve more rapidly than those prepared without sodium styrene sulfonate.