CA1194648A - Preparation of polymer powders - Google Patents
Preparation of polymer powdersInfo
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- CA1194648A CA1194648A CA000362436A CA362436A CA1194648A CA 1194648 A CA1194648 A CA 1194648A CA 000362436 A CA000362436 A CA 000362436A CA 362436 A CA362436 A CA 362436A CA 1194648 A CA1194648 A CA 1194648A
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
- C08F2/04—Polymerisation in solution
- C08F2/06—Organic solvent
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Abstract
PREPARATION OF POLYMER POWDERS
Abstract of the disclosure: Polymer powders are pre-pared from polymerizable monoethylenically unsaturated compounds, which boll at above +5°C under atmospheric pressure, by polymerizing the monomer, in the form of a 5 - 50% strength solution or emulsion in an inert or-ganic solvent which is a precipitant for the polymer, in a powder bed in the presence of a conventional poly-merization initiator, whilst maintaining the reaction mixture in the form of a powder and causing it to cir-culate, the organic solvent being removed, as vapor, from the polymerization zone during the polymerization.
Abstract of the disclosure: Polymer powders are pre-pared from polymerizable monoethylenically unsaturated compounds, which boll at above +5°C under atmospheric pressure, by polymerizing the monomer, in the form of a 5 - 50% strength solution or emulsion in an inert or-ganic solvent which is a precipitant for the polymer, in a powder bed in the presence of a conventional poly-merization initiator, whilst maintaining the reaction mixture in the form of a powder and causing it to cir-culate, the organic solvent being removed, as vapor, from the polymerization zone during the polymerization.
Description
OOZ. 0050/034090 Preparation~ polymer powders The present invention relates to a process for the preparation of a polymer powder from a polymerizable monoethylenically unsa-turated compound by polymerizing the monomer in a powder bed in the presence of a con-ventional polymeri~ation initiator, whilst maintaining the reaction mixture in the form of a powder and causing it to circulate.
French Patent 1,117,753 discloses the preparation of hydrophobic polymers, such as poIyvinyl chloride, by polymerizing ethylenically unsaturated monomers, in the presence of a diluent and of a polymerization initiator, in a polymer powder, whilst mixing the reaction mixture and maintaining it in the form of a powder during the polymerization. The polymerization can also be carried out in the absence of a diluent~ by using an ex-cess o~ the monomer and removing the heat of polymeriza-tion by evaporating the liquid monomer from the polymer-ization zone~ Where a diluent is used, water is employed and serves to remove, from the system, the heat generated during polymerization. The water is con-densed and recycled to the reaction mixture. It is not possible to produce hydrophilic polymers in powder form by this process, because the water which accumulates in the polymerization zone dissolves or swells the hydro-philic polymers so that the polymer particles agglomerate.
U.S. Patent 4,135,043 discloses a process for the preparation of hydrophilic polymers in powder form, in which water is the sole auxiliary liquid used. How-'~
ever, the use of water as a diluent has some disadvantages, because the polymerization of the monomers in part commences in the devices used to feed the monomers into the polymerizatlon zone, and the polymerization must be carried out at far above 100C in order to remove the water, under atmospheric pressure, from the polymerization zone.
It is an object of the invention to provide a process for the preparation of polymer powders, by means of which both water-soluble and water~insoluble monomers can be polymerized and which gives polymer powders which have a low residual monomer content.
We have found that this object is achieved, in the process described at the outset, if the monomex which boils at above +5C under l,013 mbar which monomer is dissolved or emul-sified, at from 5 to S0~ strength, in an inert organic solvent which is a precipitant for the polymer, is brought into contact with the powder bed and the organic solvent is removed, as vapor, from the polymerization zone.
The polymerization is preferably carried out in the absence of water. However, the solvent may contain up to 10%
by weight of water. rrO prepare polymers having a particularly low residual monomer content, a final polymerization is carried out by either adding to the reaction mixture, after the main polymerization, a polymerization initiator which decomposes at a higher temperature than does the initiator used for the main polymerization, or employing a mixture of these two initiators even for the main polymerization and then carrying _ 3 _ o.z. 0050/034~90 out the final polymerization at from about 10 to 100C
above the temperature used ~or -the main polymerization.
In this way, polymer powders of various particle size dis-tributions are obtained direct;. The particle size distribution depends in a complex manner on the reaction conditions, on the composition o~ the initiator system and on the intensity with which the reaction mixture is caused to circulate in the polymerization zone~ -~ he process according to the invention is prefer-lo entially used for homopolymerizing or copolymerizing polymerizable water-soluble ethylenically unsaturated compounds. These monomers form hydrophilic polymers.
Examples of suitable water-soluble monomers are ethyleni-cally unsaturated C3-C5-monocarboxylic acids, dicarboxy-lic acids and their anhydrides, for example acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid and itaconic acid, amides o~ ethylenically unsatura-ted carboxylic acids, preferably acrylamide and meth-acrylamide, and basic acrylamides and methacrylamides, such as dialkylaminoalkylacrylamides or dialkylamino-alkylmethacrylamides, egO dimethylaminoethylacrylamide, dimethylaminopropylacrylamide and diethylaminoethylacryl-amide, esters of ethylenically unsaturated carboxylic acids with aminoalcohols, eg. aminoethyl acrylate, di-methylaminoethyl acryla-te, diethylaminopropyl acrylate and dimethylaminoethyl methacrylate, vinylpyrrolidone and its derivatives, vinylimidazole and substituted vinyl-imidazoles, and vinylsulfones. The ethylenically ~OZ. ~050/034090 unsaturated carboxyllc acids can ~lsobe employed in a neutralized or partially neutralized ~orm, where such forms are soluble in the organic solvent.
me monomers mentioned may be homopolymerized or copoly-merized; for example, copol~mers of acrylamide and acrylic acid, copolymers of methacrylamide 9 dimethylamino-ethyl acrylate and acrylic acid, and copolymers of acryl-ic acid and acrylonitrile, or homopolymers of the mono-mers, can be prepared.
The polymerization can be carried out in the presence of crosslinking agents in order to increase the molecular weight of the polymers.- These crosslinking agents are compounds which are copolymerizable with the monomers and possess two or more ethyleni-cally unsaturated bondsO Examples of suitable crosslinking agents are butanediol diacrylate, methylene-bis-acrylamide, divinyldioxane, ethylene-divinylurea and pentaerythritol triallyl ether. The crosslinking co-monomers possessing two or more double bonds are employed in the polymerization in an amount of at most 5% by weight, preferably from 0.5 to 2% by weight9 based on total monomers. If only partial crosslinking of the polymers is necessary, these amounts are reduced to from 0 001 toO.1% by weight.
Examples of suitable water-insoluble polymeriz-able ethylenically~ unsaturated compounds are styrene, acrylonitrile, methacrylonitrile 9 esters of acrylic acid _ ~ _ oOZ0 ooSo/034~90 and methacrylic acid with Cl C'8-alcohols~ vinyl esters of C2-Cl2-carboxylic acids, monoesters and diesters of maleic acid 9 and vinyl ethers eg. vinyl methyl ether, vinyl butyl ether and vinyl cyclohexyl ether. To polymerize the monomers, they are ~irst dissolved or emulsified in an iner-t organic solvent.
Examples of suitable solvents are ketones, eg.
acetone and methyl ethyl ketone, hydrocarbons 9 such as saturated aliphatic hydrocarbons, eg. pentane, hexane, heptane, octane, isooctane and cyclic aliphatic hydro-carbons, such as cyclohexane and decalin, aromatic hydro-carbons, çg. benzene, toluene and xylene, aliphatic halo-hydrocarbons, eg. l,l 9 2-trichloro-l12,2 trifluoroethane and trichlorofluoromethane, ethers 7 eg. dimethyl ether, diethyl ether, methyl tert.-butyl ether, tetrahydrofuran and dioxane, esters, eg, methyl acetate and ethyl acetate 9 alcohols, eg. monohydric Cl-C8-alcohols, lactones, eg.
~-butyrolactone 9 dimethylsulfoxide, dimethylformamide and nitromethane.
The preferred solvents are acetone, n-hexane, cyclohexane and methyl tert.-butyl ether. In prin-ciple~ all organic solvents which are inert under the polymerization conditions and which virtually do not re-act with the reactants present in the polymerization, may be us~d, However, the inert solvents affect the particle size distribution and the molecular weigh-t of the polymers, since they can to a greater or lesser de-gree act as regulators. The boiling point of the inert organic solven~scan De from -25 to ~;~0C under atmospheric - 6 - O.Z. 0050/034090 conditions. Inert organic solvents which boil at from 20 to 150C are preferred. The solvent must be sel-ected so as not to dissolve the polymer. I~ the mono-mer is incompletely soluble in the inert sol~ent, it is emulsified therein. For -this purpose, an emulsifier must in some cases be used. Examples of suitable emulsifiers are fatty acid esters of sorbitolf ethylene oxide/propylene oxide copolymers, oxyethylated fatty acids, phenols, clO Cl8-alcohols and C10-cl8-~mines, The emulsifiers are used in amounts of from 0.01 to 1% by weight, based on monomers.
According -to the invention, the polymerization is carried ou~ in a powder bed. Suitable powders inc-lude both inorganic and organic materials in powder form, ~or example quartz powders, talc, alumin~, carbon black, - wood flour, sodium chloride and glass beads. Suitable inorganic materials in powder form include not only inert materials but also 9 for example, sodium carbonate, pot-assium carbonate, ammonium carbonate, ammonium carbamate, sodium bicarbonate 9 alkaline earth metal oxides, eg magnesium oxide and calcium oxide, magnesium carbonate and calcium carbonate. If the last-mentioned powders are used, pol~merization of monomers containing acid groups yields partially or completely neutralized poly-mers. Preferably, however, the powder initially intro-duced into the polymerization zone is an inert polymer powder which corresponds to the composition of the poly~
- 7 - o~z. 0050/~3~090 mer being freshly formed from the monomer mixture or from the monomer to be polymerized. If no polymer powder is available, these poLymers may be prepared by conventional polymerization processes, for example by mass-polymerizing the monome~ and comminuting the solid polymer, or by polymerizing the monomers in a water-in-oil emulsion and precipitating and isolating the polymer formed, or by precipitation polymerization or bead polymerization.
Examples of suitable polymerization reactors are kettles or stirred autoclaves, which may or may not be arranged as a multi-stage cascade, or combinations o~
stirred kettles with a downstream flow tube.
The material in thepolymerization zone ~ maintained in the form of a powder over the entire duration of the polymerization. Preferably, the monomer solution or emulsion is applied in a finely divided form to the pow~
der in the polymerization zone. As a rule, this step is carried out by spraying the solution or emulsion.
The monomer solution can be sprayed onto the powder bed or be atomized directly in the powder bed. The mono-mers are introduced, continuously or in portions, into the polymerization zone, a-t the rate at which they poly-merize During the polymerization, the reaction mix-ture mus-t be caused to circulate adequately. Prefer-ably, this is done by stirring the mixture. The heat generated during pol~nerization, and the heat generated by circulating the powder, are removed by continuously evaporating the solvent from the reaction zone. Pre-- 8 - O.Z0 0050/03409~
ferably, the concentration of the monomers in the organ ic solvent is selected to be such that on complete polymerization of the monomers the enthalpy of polymeri-zation which is liberated just; suffices to remove the organic solvents completely by evaporation, under the prevailing reaction conditions, from the polymerization zone. The concentration of the monomers in the sol-vent is preferably in the range from 15 to 35% by weight.
The polymerization is carried out with the aid lo of the conventional free radical catalysts. Examples of suitable catalysts are peroxides, hydroperoxides, azo compounds and C~C-labile compounds. The polymeriza-tion initiators can also bé employed conjointly with a suitable accelerator. Suitable accelerators are reducing compounds, preferably amines derived from (saturated) cyclic compounds or from phenyl compounds, and are used by themselves or in the presence of an or~
ganic compound of a transition metal. The pol~meri-zation initiators can be introduced into -the polymeriza-tion zone either together with the monomer solution oremulsion or separately therefrom. If the heat liberated by the polymerization, together with the heat generated by stirring or by neutralization, if any, does not su~fice to remove the solvent from the system, it is necessary additionally to supply heat to the reaction mixture so that the solvent is completely removed from the polymerization zone during the polymerization and the reaction mixture is maintained in the form of a powder.
If on the other hand the amount o~ solvent should be too \
~ 9 - o.Z~ OOS0/03~090 low to remove the entire heat generated during the poly-merization, it is necessary to cool the reaction mixture~
The polymerization of the monomers can be carried out a-t ~rom -25 to 160C, preferably from 20 to 100C, depending on the reactivity of the monomers and the ef~ectiveness of the initiator system. Since the re-action mixture is maintained in the ~orm of a powder throughout the polymerization 7 the polymerization temperature is about 10C below the melting point or incipient softening range of the polymer 9 SO that no agglomeration occurs. The polymerization can be carried out under atmospheric pressure, under reduced pressure or under superatmospheric pressure of up to 25 bar, pre~erably up to 4 bar. The novel process can be carried out batchwise or continuously, and in both cases suitable containers for the reaction zone are, ~or example, stirred kettles or dynamic mixers o~ all kinds.
In continuous operation, the monomer solution or emul-sion is mixed with the initiator system and then fed to the reaction zone continuously or at intervals, and the polymer is continuously or intermittently removed ~rom the reaction zone by a suitable discharge device, for example a screw. Per unit time, about the same amount of polymer is removed as the amount o~ monomer introduced into the reaction zone. Advantageously, the monomer solution and the initiator system are cooled be~ore being introduced into the reaction zone, ie. the temperature o~
the monomer solution is ~rom -40 to +20C.
In order to obtain a polymer powder having a ~ 10 - O.Z~ 0050/034090 particularly lo~ monomer content, the main polymerization is followed by a final polymerization. For this purpose, the reaction mixture is heated to 10 100C above the temperature at which the main polymerization has been carried out. To polymerize the residual monomer a polymerization initiator which decomposes at a higher temperature is preferably added to the monomer from the start, but it is also possible to spray a solution of the initiator in an organic solvent onto the reaction mixture after conclusion of the main polymerizationO
In this last-mentioned case, the same initiator as is used in the main polymerization may be employed. Pre-ferably~ however, the initiator used for the final poly-merization decomposes at a higher temperature than the initiator used for the main polymerization. For the final polymerization, from 0.05 to 0.8, preferably from 0.15 toO.5~mole % ~ polymerization initiator is used per mole ofmonomerormonomermixture. The decomposition tempera-tures which correspond to a half-life of 1 hour differ by at least 20C between the polymerization initiator for the main polymerization and for the final polymerization. Where mixtures of polymerization initiators are employed, from 0.1 to 5 mole %, based on monomers, of the polymerization initiator having the lower decomposition temperature, \
- 11 O~Z0 0050/034090 and from 0~05 to 0.8 mole %, based on monomers, of the polymerization initiator having the higher decomposition temperature, are used. The polymer powders ob-tained have particle diameters of from 10 ~m to 2 cm, preferably ~rom 0.1 to 5 mm.
The polymers prepared by the process according -to the invention have a different molecular weight dis-tribution from those obtained, for example, by precipi tation polymerization or by polymerization in a water-in-oil emulsion. Compared with precipitation polymeri-zation, the novel process gives a substantially higher space-time yield. Furthermore, the conventional working-up steps for isolating and drying the polymers are not needed.
me polymers obtained by the novel process are employed for the conventional purposes of these materials.
For example, copolymers of acrylamide and acrylic acid are employed as flocculating agents in the paper indus-try~ in mining and in sewage farms, water-soluble alkali metal salts or alkaline earth metal salts of copolymers of acrylonitrile and acrylic acid are used as textile sizes-~ partially neutralized copolymers of styrene and maleic anhydride are used as paper sizes, homopolymers and copolymers of acrylonitrile are used as agents for increasing the strength of paper, and copolymers of N-~inylpyrrolidone are used as hair strengtheners in cos-metics.
In the Examples which follow, parts and percent-ages are by weight. The K values were determined by \
- 12 - O.Z~ OoS0/0340go the method of H. Fikentscher, Cellulosechemie 1~ (1932), 58-64 and 71-74, at 25C; K = k 0 103 Preparation of a copolymer of styrene and maleic anhy~
dride This copolymer was produced batchwise. The polymerization vessel was a cylindrical glass vessel o~
5 liters capaclty 9 equipped with a spiral stirrer and a descending condenser. A spray nozzle opened into the glass vessel and the monomer solution, togeth~r with the initiator, was sprayed from this nozzle onto the polymer powder initially introduced into the vessel. A
nitrogen line furthermore led into the glass vessel so that the polymerization could be carried out under a nitrogen atmosphere. The vessel was heated by means of an oilbath. The monomer solution was mixed with the initiator solution in a static mixer. A heat exchanger was built into the line through which the mono-mer was fed to the static mixer, so that the monomer solution could be cooled if required.
A tap was built into the line leading to the condenser so as to be able to separate out solids entrained by the stream of nitrogen or by the evaporating inert organic solvent 1,500 g o~ a nylon powder obtained from adipic acid and hexamethylenediamine and having a particle diameter of 1-2 mm were initially introduced into the apparatus described above and heated to 80C, with vigorous circulation.
A solution of 625 g of styrene and 625 g of - 13 - O,Z~ 0050/034090 maleic anhydride in 39750 g ~ methyltert,-butyl e~r was combined9inthestatic mixer9ina volumetric flow ratio oflO:l, with an initiator solution of 14.8 g of bis-(4-tert.-butyl-cyclohexyl) peroxydicarbonate in 500 ml of methyl tert.-butyl ether, and the mixture wasprogressively sprayed, over 4.5 hours 9 onto the agitated solid-particle bed of nylon powder. The polymerization temperature was 75C, During the polymerization, the reaction mix-ture was maintained in the form of a powder in the poly-lo merization zone and the solvent, namely methyl tert,-kutyl ether, was continuously evaporated from the re-action zone by the heat liberated by polymerization and by the energy introduced into the system as a result of stirring the powder bed, and was condensed in the des-cending condenser, The copolymer of styrene and maleic anhydride, separated from the inert material initially introduced, was solvent-free and had a K value of 33.5 (0.2% strength solution in toluene), Resi-~ual monomers were not detectable.
The copolymer was soluble in dilute aqueous sodium hydroxide solution and was used, in a partially or completely neutralized form, as a paper size, EX~PLE 2 Preparation of polystyrene Using the polymerization apparatus described in Example 1, 1,500 g of polystyrene of particle diameter 1-2 mm were introduced and heated to 94C, with constan-t circulation, A solution of 300 g of styrene in
French Patent 1,117,753 discloses the preparation of hydrophobic polymers, such as poIyvinyl chloride, by polymerizing ethylenically unsaturated monomers, in the presence of a diluent and of a polymerization initiator, in a polymer powder, whilst mixing the reaction mixture and maintaining it in the form of a powder during the polymerization. The polymerization can also be carried out in the absence of a diluent~ by using an ex-cess o~ the monomer and removing the heat of polymeriza-tion by evaporating the liquid monomer from the polymer-ization zone~ Where a diluent is used, water is employed and serves to remove, from the system, the heat generated during polymerization. The water is con-densed and recycled to the reaction mixture. It is not possible to produce hydrophilic polymers in powder form by this process, because the water which accumulates in the polymerization zone dissolves or swells the hydro-philic polymers so that the polymer particles agglomerate.
U.S. Patent 4,135,043 discloses a process for the preparation of hydrophilic polymers in powder form, in which water is the sole auxiliary liquid used. How-'~
ever, the use of water as a diluent has some disadvantages, because the polymerization of the monomers in part commences in the devices used to feed the monomers into the polymerizatlon zone, and the polymerization must be carried out at far above 100C in order to remove the water, under atmospheric pressure, from the polymerization zone.
It is an object of the invention to provide a process for the preparation of polymer powders, by means of which both water-soluble and water~insoluble monomers can be polymerized and which gives polymer powders which have a low residual monomer content.
We have found that this object is achieved, in the process described at the outset, if the monomex which boils at above +5C under l,013 mbar which monomer is dissolved or emul-sified, at from 5 to S0~ strength, in an inert organic solvent which is a precipitant for the polymer, is brought into contact with the powder bed and the organic solvent is removed, as vapor, from the polymerization zone.
The polymerization is preferably carried out in the absence of water. However, the solvent may contain up to 10%
by weight of water. rrO prepare polymers having a particularly low residual monomer content, a final polymerization is carried out by either adding to the reaction mixture, after the main polymerization, a polymerization initiator which decomposes at a higher temperature than does the initiator used for the main polymerization, or employing a mixture of these two initiators even for the main polymerization and then carrying _ 3 _ o.z. 0050/034~90 out the final polymerization at from about 10 to 100C
above the temperature used ~or -the main polymerization.
In this way, polymer powders of various particle size dis-tributions are obtained direct;. The particle size distribution depends in a complex manner on the reaction conditions, on the composition o~ the initiator system and on the intensity with which the reaction mixture is caused to circulate in the polymerization zone~ -~ he process according to the invention is prefer-lo entially used for homopolymerizing or copolymerizing polymerizable water-soluble ethylenically unsaturated compounds. These monomers form hydrophilic polymers.
Examples of suitable water-soluble monomers are ethyleni-cally unsaturated C3-C5-monocarboxylic acids, dicarboxy-lic acids and their anhydrides, for example acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid and itaconic acid, amides o~ ethylenically unsatura-ted carboxylic acids, preferably acrylamide and meth-acrylamide, and basic acrylamides and methacrylamides, such as dialkylaminoalkylacrylamides or dialkylamino-alkylmethacrylamides, egO dimethylaminoethylacrylamide, dimethylaminopropylacrylamide and diethylaminoethylacryl-amide, esters of ethylenically unsaturated carboxylic acids with aminoalcohols, eg. aminoethyl acrylate, di-methylaminoethyl acryla-te, diethylaminopropyl acrylate and dimethylaminoethyl methacrylate, vinylpyrrolidone and its derivatives, vinylimidazole and substituted vinyl-imidazoles, and vinylsulfones. The ethylenically ~OZ. ~050/034090 unsaturated carboxyllc acids can ~lsobe employed in a neutralized or partially neutralized ~orm, where such forms are soluble in the organic solvent.
me monomers mentioned may be homopolymerized or copoly-merized; for example, copol~mers of acrylamide and acrylic acid, copolymers of methacrylamide 9 dimethylamino-ethyl acrylate and acrylic acid, and copolymers of acryl-ic acid and acrylonitrile, or homopolymers of the mono-mers, can be prepared.
The polymerization can be carried out in the presence of crosslinking agents in order to increase the molecular weight of the polymers.- These crosslinking agents are compounds which are copolymerizable with the monomers and possess two or more ethyleni-cally unsaturated bondsO Examples of suitable crosslinking agents are butanediol diacrylate, methylene-bis-acrylamide, divinyldioxane, ethylene-divinylurea and pentaerythritol triallyl ether. The crosslinking co-monomers possessing two or more double bonds are employed in the polymerization in an amount of at most 5% by weight, preferably from 0.5 to 2% by weight9 based on total monomers. If only partial crosslinking of the polymers is necessary, these amounts are reduced to from 0 001 toO.1% by weight.
Examples of suitable water-insoluble polymeriz-able ethylenically~ unsaturated compounds are styrene, acrylonitrile, methacrylonitrile 9 esters of acrylic acid _ ~ _ oOZ0 ooSo/034~90 and methacrylic acid with Cl C'8-alcohols~ vinyl esters of C2-Cl2-carboxylic acids, monoesters and diesters of maleic acid 9 and vinyl ethers eg. vinyl methyl ether, vinyl butyl ether and vinyl cyclohexyl ether. To polymerize the monomers, they are ~irst dissolved or emulsified in an iner-t organic solvent.
Examples of suitable solvents are ketones, eg.
acetone and methyl ethyl ketone, hydrocarbons 9 such as saturated aliphatic hydrocarbons, eg. pentane, hexane, heptane, octane, isooctane and cyclic aliphatic hydro-carbons, such as cyclohexane and decalin, aromatic hydro-carbons, çg. benzene, toluene and xylene, aliphatic halo-hydrocarbons, eg. l,l 9 2-trichloro-l12,2 trifluoroethane and trichlorofluoromethane, ethers 7 eg. dimethyl ether, diethyl ether, methyl tert.-butyl ether, tetrahydrofuran and dioxane, esters, eg, methyl acetate and ethyl acetate 9 alcohols, eg. monohydric Cl-C8-alcohols, lactones, eg.
~-butyrolactone 9 dimethylsulfoxide, dimethylformamide and nitromethane.
The preferred solvents are acetone, n-hexane, cyclohexane and methyl tert.-butyl ether. In prin-ciple~ all organic solvents which are inert under the polymerization conditions and which virtually do not re-act with the reactants present in the polymerization, may be us~d, However, the inert solvents affect the particle size distribution and the molecular weigh-t of the polymers, since they can to a greater or lesser de-gree act as regulators. The boiling point of the inert organic solven~scan De from -25 to ~;~0C under atmospheric - 6 - O.Z. 0050/034090 conditions. Inert organic solvents which boil at from 20 to 150C are preferred. The solvent must be sel-ected so as not to dissolve the polymer. I~ the mono-mer is incompletely soluble in the inert sol~ent, it is emulsified therein. For -this purpose, an emulsifier must in some cases be used. Examples of suitable emulsifiers are fatty acid esters of sorbitolf ethylene oxide/propylene oxide copolymers, oxyethylated fatty acids, phenols, clO Cl8-alcohols and C10-cl8-~mines, The emulsifiers are used in amounts of from 0.01 to 1% by weight, based on monomers.
According -to the invention, the polymerization is carried ou~ in a powder bed. Suitable powders inc-lude both inorganic and organic materials in powder form, ~or example quartz powders, talc, alumin~, carbon black, - wood flour, sodium chloride and glass beads. Suitable inorganic materials in powder form include not only inert materials but also 9 for example, sodium carbonate, pot-assium carbonate, ammonium carbonate, ammonium carbamate, sodium bicarbonate 9 alkaline earth metal oxides, eg magnesium oxide and calcium oxide, magnesium carbonate and calcium carbonate. If the last-mentioned powders are used, pol~merization of monomers containing acid groups yields partially or completely neutralized poly-mers. Preferably, however, the powder initially intro-duced into the polymerization zone is an inert polymer powder which corresponds to the composition of the poly~
- 7 - o~z. 0050/~3~090 mer being freshly formed from the monomer mixture or from the monomer to be polymerized. If no polymer powder is available, these poLymers may be prepared by conventional polymerization processes, for example by mass-polymerizing the monome~ and comminuting the solid polymer, or by polymerizing the monomers in a water-in-oil emulsion and precipitating and isolating the polymer formed, or by precipitation polymerization or bead polymerization.
Examples of suitable polymerization reactors are kettles or stirred autoclaves, which may or may not be arranged as a multi-stage cascade, or combinations o~
stirred kettles with a downstream flow tube.
The material in thepolymerization zone ~ maintained in the form of a powder over the entire duration of the polymerization. Preferably, the monomer solution or emulsion is applied in a finely divided form to the pow~
der in the polymerization zone. As a rule, this step is carried out by spraying the solution or emulsion.
The monomer solution can be sprayed onto the powder bed or be atomized directly in the powder bed. The mono-mers are introduced, continuously or in portions, into the polymerization zone, a-t the rate at which they poly-merize During the polymerization, the reaction mix-ture mus-t be caused to circulate adequately. Prefer-ably, this is done by stirring the mixture. The heat generated during pol~nerization, and the heat generated by circulating the powder, are removed by continuously evaporating the solvent from the reaction zone. Pre-- 8 - O.Z0 0050/03409~
ferably, the concentration of the monomers in the organ ic solvent is selected to be such that on complete polymerization of the monomers the enthalpy of polymeri-zation which is liberated just; suffices to remove the organic solvents completely by evaporation, under the prevailing reaction conditions, from the polymerization zone. The concentration of the monomers in the sol-vent is preferably in the range from 15 to 35% by weight.
The polymerization is carried out with the aid lo of the conventional free radical catalysts. Examples of suitable catalysts are peroxides, hydroperoxides, azo compounds and C~C-labile compounds. The polymeriza-tion initiators can also bé employed conjointly with a suitable accelerator. Suitable accelerators are reducing compounds, preferably amines derived from (saturated) cyclic compounds or from phenyl compounds, and are used by themselves or in the presence of an or~
ganic compound of a transition metal. The pol~meri-zation initiators can be introduced into -the polymeriza-tion zone either together with the monomer solution oremulsion or separately therefrom. If the heat liberated by the polymerization, together with the heat generated by stirring or by neutralization, if any, does not su~fice to remove the solvent from the system, it is necessary additionally to supply heat to the reaction mixture so that the solvent is completely removed from the polymerization zone during the polymerization and the reaction mixture is maintained in the form of a powder.
If on the other hand the amount o~ solvent should be too \
~ 9 - o.Z~ OOS0/03~090 low to remove the entire heat generated during the poly-merization, it is necessary to cool the reaction mixture~
The polymerization of the monomers can be carried out a-t ~rom -25 to 160C, preferably from 20 to 100C, depending on the reactivity of the monomers and the ef~ectiveness of the initiator system. Since the re-action mixture is maintained in the ~orm of a powder throughout the polymerization 7 the polymerization temperature is about 10C below the melting point or incipient softening range of the polymer 9 SO that no agglomeration occurs. The polymerization can be carried out under atmospheric pressure, under reduced pressure or under superatmospheric pressure of up to 25 bar, pre~erably up to 4 bar. The novel process can be carried out batchwise or continuously, and in both cases suitable containers for the reaction zone are, ~or example, stirred kettles or dynamic mixers o~ all kinds.
In continuous operation, the monomer solution or emul-sion is mixed with the initiator system and then fed to the reaction zone continuously or at intervals, and the polymer is continuously or intermittently removed ~rom the reaction zone by a suitable discharge device, for example a screw. Per unit time, about the same amount of polymer is removed as the amount o~ monomer introduced into the reaction zone. Advantageously, the monomer solution and the initiator system are cooled be~ore being introduced into the reaction zone, ie. the temperature o~
the monomer solution is ~rom -40 to +20C.
In order to obtain a polymer powder having a ~ 10 - O.Z~ 0050/034090 particularly lo~ monomer content, the main polymerization is followed by a final polymerization. For this purpose, the reaction mixture is heated to 10 100C above the temperature at which the main polymerization has been carried out. To polymerize the residual monomer a polymerization initiator which decomposes at a higher temperature is preferably added to the monomer from the start, but it is also possible to spray a solution of the initiator in an organic solvent onto the reaction mixture after conclusion of the main polymerizationO
In this last-mentioned case, the same initiator as is used in the main polymerization may be employed. Pre-ferably~ however, the initiator used for the final poly-merization decomposes at a higher temperature than the initiator used for the main polymerization. For the final polymerization, from 0.05 to 0.8, preferably from 0.15 toO.5~mole % ~ polymerization initiator is used per mole ofmonomerormonomermixture. The decomposition tempera-tures which correspond to a half-life of 1 hour differ by at least 20C between the polymerization initiator for the main polymerization and for the final polymerization. Where mixtures of polymerization initiators are employed, from 0.1 to 5 mole %, based on monomers, of the polymerization initiator having the lower decomposition temperature, \
- 11 O~Z0 0050/034090 and from 0~05 to 0.8 mole %, based on monomers, of the polymerization initiator having the higher decomposition temperature, are used. The polymer powders ob-tained have particle diameters of from 10 ~m to 2 cm, preferably ~rom 0.1 to 5 mm.
The polymers prepared by the process according -to the invention have a different molecular weight dis-tribution from those obtained, for example, by precipi tation polymerization or by polymerization in a water-in-oil emulsion. Compared with precipitation polymeri-zation, the novel process gives a substantially higher space-time yield. Furthermore, the conventional working-up steps for isolating and drying the polymers are not needed.
me polymers obtained by the novel process are employed for the conventional purposes of these materials.
For example, copolymers of acrylamide and acrylic acid are employed as flocculating agents in the paper indus-try~ in mining and in sewage farms, water-soluble alkali metal salts or alkaline earth metal salts of copolymers of acrylonitrile and acrylic acid are used as textile sizes-~ partially neutralized copolymers of styrene and maleic anhydride are used as paper sizes, homopolymers and copolymers of acrylonitrile are used as agents for increasing the strength of paper, and copolymers of N-~inylpyrrolidone are used as hair strengtheners in cos-metics.
In the Examples which follow, parts and percent-ages are by weight. The K values were determined by \
- 12 - O.Z~ OoS0/0340go the method of H. Fikentscher, Cellulosechemie 1~ (1932), 58-64 and 71-74, at 25C; K = k 0 103 Preparation of a copolymer of styrene and maleic anhy~
dride This copolymer was produced batchwise. The polymerization vessel was a cylindrical glass vessel o~
5 liters capaclty 9 equipped with a spiral stirrer and a descending condenser. A spray nozzle opened into the glass vessel and the monomer solution, togeth~r with the initiator, was sprayed from this nozzle onto the polymer powder initially introduced into the vessel. A
nitrogen line furthermore led into the glass vessel so that the polymerization could be carried out under a nitrogen atmosphere. The vessel was heated by means of an oilbath. The monomer solution was mixed with the initiator solution in a static mixer. A heat exchanger was built into the line through which the mono-mer was fed to the static mixer, so that the monomer solution could be cooled if required.
A tap was built into the line leading to the condenser so as to be able to separate out solids entrained by the stream of nitrogen or by the evaporating inert organic solvent 1,500 g o~ a nylon powder obtained from adipic acid and hexamethylenediamine and having a particle diameter of 1-2 mm were initially introduced into the apparatus described above and heated to 80C, with vigorous circulation.
A solution of 625 g of styrene and 625 g of - 13 - O,Z~ 0050/034090 maleic anhydride in 39750 g ~ methyltert,-butyl e~r was combined9inthestatic mixer9ina volumetric flow ratio oflO:l, with an initiator solution of 14.8 g of bis-(4-tert.-butyl-cyclohexyl) peroxydicarbonate in 500 ml of methyl tert.-butyl ether, and the mixture wasprogressively sprayed, over 4.5 hours 9 onto the agitated solid-particle bed of nylon powder. The polymerization temperature was 75C, During the polymerization, the reaction mix-ture was maintained in the form of a powder in the poly-lo merization zone and the solvent, namely methyl tert,-kutyl ether, was continuously evaporated from the re-action zone by the heat liberated by polymerization and by the energy introduced into the system as a result of stirring the powder bed, and was condensed in the des-cending condenser, The copolymer of styrene and maleic anhydride, separated from the inert material initially introduced, was solvent-free and had a K value of 33.5 (0.2% strength solution in toluene), Resi-~ual monomers were not detectable.
The copolymer was soluble in dilute aqueous sodium hydroxide solution and was used, in a partially or completely neutralized form, as a paper size, EX~PLE 2 Preparation of polystyrene Using the polymerization apparatus described in Example 1, 1,500 g of polystyrene of particle diameter 1-2 mm were introduced and heated to 94C, with constan-t circulation, A solution of 300 g of styrene in
2,100 g of n-hexane was then combined in a static mixer, - 14 ~ o~z~ 0~50~034090 in a volumetric flow ratio of lO :19 with a sol~tion of 13.8 g of a polymerization initiator, namely bis-(4-ter~.-butylcyclohexyl) peroxydicarbonate, in 500 ml of n-hexane an~ the mixtllre was sprayed continuously, over 6 hours, onto the solid-particle bed of polystyrene.
The polymerization temperature was soc. . During the polymerization, the material in the polymerization zone was maintained in the fo~m of a powder and the solvent was distilled off continuously. A solvent-free lo polymer having a K value of 60~4 (measured in 0.2%
strength solution in toluene) and a residual monomer content of 0.45~ was obtained.
~he polymer powder ~as used for the production of moldings or, after impregnation with a blowing agent (eg. pentane), for the production of foam moldings.
Preparation of polymethyl methacrylate 1,200 g of magnesium oxide o~ particle diameter 0.1 ~m were initially introduced into the apparatus des-cribed in Example l. The temperature of the oilbath 2G was set to 100C. A solution of l,000 g of methyl meth~
~crylate in 3,000g of n-hexane wascombined,in thestaticmixer,in a vQlumetric flow ratio of lO:l, with a solution of 10.5 g of a polymerization initiator, namely bis-(4-tert.-butylcyciohexyl) peroxydicarbonate, in 500 ml of n-hex-ane, and the mixture was sprayed progressively, over 4 hours~ onto the agitated solid-particle bed. During the polymerization, the reaction mixture was maintained in the form of a powder and the solvent was distilled - 15 - O.ZO 0050/034090 off continuously. The po]ymethyl methacrylate, detached from the inert starting material~
had a K value of 48 (measured in 0.2% strength solution in acetone) and a residual monomer content of 0~8%.
The polymer was used for the production of moldings.
Preparation of a copolymer of acrylamide and sodium acrylate 1,500 g of polyacrylamide having a K value of 53 and 616 g of sodium bicarbonate were introduced into the polymerization apparatus described in Example 1, and the oilbath was brought to 90C~ A solution of 600 g of acrylic acid and 400 g o~ acrylamide dissolved in 3,000 g of acetone, and an initiator solution consisting of 16.6 g of bis-~4~tert.-butylcyclohexyl) peroxydicarbonate in 500 ml of acetone were then brought together, in a volumetric flow ratio of 10:1, by means of a static mixer, and the mixture was sprayed onto the agitated material initially introduced into the apparatus. During the polymerization9 the reaction mixture was maintained in the form of a powder and the acetone was distilled from the polymerization zone. The polymerization tempera-ture was 75C. The sodium salt of a copolymer of acrylamide and acrylic acid was obtained; it dissolved ~ery readily in water, with virtually no evolution of carbon dioxide. The copolymer was virtually free from acetone and had a K value o~ 52.8 (determined in 5% strength NaC1 solution~. The residual monomer content was 2.40~o. `
~9~
~ 16 - o~zO 005/034090 To reduce -the residua:L monomer content, the material was subjected to a final polymerization by spraying a solution of 5 g of benzoyl peroxide in 100 g of acetone onto the agitated copolymer, at 100C. The residual monomer content fell to about 0.1%, with a slight drop in K value to 51.5.
The copolymer was used as a flocculating agent in sewage farmsO
Preparation o~ a copolymer o~ acrylamide and ammonium acrylate 1,500 g of polyacrylamide9 of K value 5~, were introduced into the apparatus described in Example 1.
The reacti~n chamber was exposed to gaseous ammonia and the temperature of the oilbath was brought to 90C, A
solution of 600 g of acrylic acid and 400 g o~ acryl-amide in 3,000 g of methyl tert.-butyl ether was then combined, in a vvlumetric ~low ratio of 10 1 in a static mixer, with an initiator solution consisting of 16~6 g of bis-(4 tert.-butylcyclohexyl) peroxydicarbonate in 500 ml of methyl tert.-butyl ether, containin~ 10% of methanol7 and the mixture was sprayed continuously, over 4 hours, onto the agitated material initially introduced.
During the polymerization, the solid-particle bed was circulated e~ficiently and ammonia was passed into the polymerization zone. The polymerization -temperature was 75Cc The methyl tert.-butyl ether introduced into the polymerization zone together with the monomer was removed continuously from the reaction zone, during the polymerization, by evaporation. After completion of the addition of the monomer solution and of the poly-merization initiator the mixture was kept at 90C for a further 30 minutes. A copolymer of acrylamide and ammonium acrylate, which had a K value of 46 and was virtually odorless, was obtained. The particle diameter o~ the polymer was from 0.1 to 2 mm.
Aqueous solutions of the copol-ymer were used as floccu-lating agen~ in papermaking.
lo Preparation of polyacrylamide 1,500 g of polyacrylamide having aK value of 53 and a mean particle diameter of 1 mm were introduced into the polymerization apparatus described in Example 1. The oilbath was brought to 90C. A solution of 1,000 g of acrylamide and 1.2 g of methylene-bis-acrylamide in
The polymerization temperature was soc. . During the polymerization, the material in the polymerization zone was maintained in the fo~m of a powder and the solvent was distilled off continuously. A solvent-free lo polymer having a K value of 60~4 (measured in 0.2%
strength solution in toluene) and a residual monomer content of 0.45~ was obtained.
~he polymer powder ~as used for the production of moldings or, after impregnation with a blowing agent (eg. pentane), for the production of foam moldings.
Preparation of polymethyl methacrylate 1,200 g of magnesium oxide o~ particle diameter 0.1 ~m were initially introduced into the apparatus des-cribed in Example l. The temperature of the oilbath 2G was set to 100C. A solution of l,000 g of methyl meth~
~crylate in 3,000g of n-hexane wascombined,in thestaticmixer,in a vQlumetric flow ratio of lO:l, with a solution of 10.5 g of a polymerization initiator, namely bis-(4-tert.-butylcyciohexyl) peroxydicarbonate, in 500 ml of n-hex-ane, and the mixture was sprayed progressively, over 4 hours~ onto the agitated solid-particle bed. During the polymerization, the reaction mixture was maintained in the form of a powder and the solvent was distilled - 15 - O.ZO 0050/034090 off continuously. The po]ymethyl methacrylate, detached from the inert starting material~
had a K value of 48 (measured in 0.2% strength solution in acetone) and a residual monomer content of 0~8%.
The polymer was used for the production of moldings.
Preparation of a copolymer of acrylamide and sodium acrylate 1,500 g of polyacrylamide having a K value of 53 and 616 g of sodium bicarbonate were introduced into the polymerization apparatus described in Example 1, and the oilbath was brought to 90C~ A solution of 600 g of acrylic acid and 400 g o~ acrylamide dissolved in 3,000 g of acetone, and an initiator solution consisting of 16.6 g of bis-~4~tert.-butylcyclohexyl) peroxydicarbonate in 500 ml of acetone were then brought together, in a volumetric flow ratio of 10:1, by means of a static mixer, and the mixture was sprayed onto the agitated material initially introduced into the apparatus. During the polymerization9 the reaction mixture was maintained in the form of a powder and the acetone was distilled from the polymerization zone. The polymerization tempera-ture was 75C. The sodium salt of a copolymer of acrylamide and acrylic acid was obtained; it dissolved ~ery readily in water, with virtually no evolution of carbon dioxide. The copolymer was virtually free from acetone and had a K value o~ 52.8 (determined in 5% strength NaC1 solution~. The residual monomer content was 2.40~o. `
~9~
~ 16 - o~zO 005/034090 To reduce -the residua:L monomer content, the material was subjected to a final polymerization by spraying a solution of 5 g of benzoyl peroxide in 100 g of acetone onto the agitated copolymer, at 100C. The residual monomer content fell to about 0.1%, with a slight drop in K value to 51.5.
The copolymer was used as a flocculating agent in sewage farmsO
Preparation o~ a copolymer o~ acrylamide and ammonium acrylate 1,500 g of polyacrylamide9 of K value 5~, were introduced into the apparatus described in Example 1.
The reacti~n chamber was exposed to gaseous ammonia and the temperature of the oilbath was brought to 90C, A
solution of 600 g of acrylic acid and 400 g o~ acryl-amide in 3,000 g of methyl tert.-butyl ether was then combined, in a vvlumetric ~low ratio of 10 1 in a static mixer, with an initiator solution consisting of 16~6 g of bis-(4 tert.-butylcyclohexyl) peroxydicarbonate in 500 ml of methyl tert.-butyl ether, containin~ 10% of methanol7 and the mixture was sprayed continuously, over 4 hours, onto the agitated material initially introduced.
During the polymerization, the solid-particle bed was circulated e~ficiently and ammonia was passed into the polymerization zone. The polymerization -temperature was 75Cc The methyl tert.-butyl ether introduced into the polymerization zone together with the monomer was removed continuously from the reaction zone, during the polymerization, by evaporation. After completion of the addition of the monomer solution and of the poly-merization initiator the mixture was kept at 90C for a further 30 minutes. A copolymer of acrylamide and ammonium acrylate, which had a K value of 46 and was virtually odorless, was obtained. The particle diameter o~ the polymer was from 0.1 to 2 mm.
Aqueous solutions of the copol-ymer were used as floccu-lating agen~ in papermaking.
lo Preparation of polyacrylamide 1,500 g of polyacrylamide having aK value of 53 and a mean particle diameter of 1 mm were introduced into the polymerization apparatus described in Example 1. The oilbath was brought to 90C. A solution of 1,000 g of acrylamide and 1.2 g of methylene-bis-acrylamide in
3,000 g of acetone was then combined with a solution of 16.6 g of a polymerization initiator, namely bis-(4-tert.-butylcyclohexyl) peroxydicarbonate, in 500 ml of acetone, in a volumetric flow ratio of lO:l,by means of a static mixer and the mixture was sprayed progressively, over 4 hours, onto the agitated polyacrylamide pow~er.
During the polymerization, the reaction mixture was main-tained in the form of a powder and the acetone was con-tinuously removed from the polymerization zone by evaporation.
The polymerization temperature was 75C. A virtually non-hydrolyzed polyacrylamide was obtained, which was com~le-tely soluble in water and had a K value of 67.
The par-ticle diameter of the polymer was from 0.1 to 2 mm.
~9~6~
~ 18 - o~ ooSo/o34o9o Aqueous solutions of the copolymer were used as a paper strengthener.
Preparation of polyacrylamide The polymerization apparatus used was a steel pressure kettle which was equipped with a spiral stirrer and had a capacity of 40 liters. The solution of the monomer and the solution of the polymerization initia-tor were mixed in a temperature-controlled spray lance and the mixture was sprayed onto the inert material, in powder form, which had first been introduced into the pressure kettle. The powder formed during thepolymeri-zation wa~s discharged from the polymerization zone by means of a screw.
15 kg o~ polyacrylamide, having a K value of 53 and a particle diameter of from 1 to 4 mm were ~irst introduced into the pressure kettle. The temperature of the heating was set to 80C. 8 liters per hour of a 25% strength solution o~ acrylamide in acetone and 600 ml/hour of a solution in acetone of 0.18 mole % of bis-(4-tert.-butyl-cyclohexyl) peroxydicarbonate and 0.072 mole% of tert~-butyl peroctoate, the percentages being based on acryl-amide~ were then combined by means of a static mixerg and the mixture of the monomer and the polymerization initiators was sprayed onto the poly-acrylamide powder bed over 70 hours. During the - 19 - o~z~ 0050~03~090 polymerization, the reaction mixture was maintained in the form of a powder and the acetone was removed com-pletely from the reaction chamber, as vapor, due to the heat of polymeriza-tion and the energy introduced by stir-ring. The polymer powder formed during the polymeri-zation was discharged by means of a screw. The poly-merization temperature was 75C. 150 kg of freshly formed polymer, having a particle diameter of from 0.1 to 5 mm and a K value of 62 (determined in 0 2% strength aqueous solution) were obtained.
15 kg of polyacrylamide having a K value of 53 and a particle diameter of from 1 to 4 mm were introduced into the continuous polymerization apparatus described in Example 7. The heating of the pressure kettle was set to &oc. 8 liters per hour of a 25~ strength solution of acrylamide in acetone, containing 5~ of water, and 500 ml per hour of an initiator solution in acetone containing 0 15 mole % of bis-(4-tert. butylcyclohexyl) p~rôxydicarbonate, 0.06 mole % of tert.-butyl peroctoate and 0 024 mole % of dibenzoyl peroxide, the percentages being based on acrylamide, were combined by means of a static mixer, and the mixture was sprayed, over a period of 70 hours,onto the solid-particle powder bed. During the polymerization, the bed was circulated continuously and the solvent, as well as the water introduced with the solvent into the polymeri-- 20 ~ O~Z~ 0050/034090 zation zone, were evaporated continuously, thereby main-taining the reaction mixture in the form of a powder during the polymerization. The polymerization temp~rature was 75C. 150 kg of freshly formed poly-acrylamide were obtained; this material was solvent-free and had a K value of 87 (determined in 0 2% strength aqueous solution) and a residual monomer content of 0.9%.
20 kg of this polyacrylamide were subjected to a final polymerization by heating for 4 hours at 110C~
which caused the decomposition of the polymerization initiators (tert.-butyl peroctoate and dibenzoyl perox-ide) present in the product. The residual monomer content fell to about 0.1%, the K value of the product being 86.
Preparation of a copolymer of 80% of acrylamide and 20~o o~ acrylic acid 15 kg of polyacrylamide having a K value of 5~
of 53 and a particle diameter of from 1 to 4 mm were introduced into the polymerization apparatus described in Example 7. The protective heating of the kettle wa~ set to 80Co 8 liters per hour of a 25% strength . solution o~ 80% of acrylamide and 20~ of acrylic acid in acetone and 700 ml per hour of an initiator solution in ace-tone of 0.21 mole %of bis-(4 tert.-butylcyclohexyl peroxydi-carbonate and 0.084 mole % o~ tert.-butyl peroc-toate 9 the percentages being based on monomer mixturet were then combined by means o~ a s-tatic mixer, and the mixture was sprayed 9 over 6~ hours, onto the 6~
- 2~ - O.Z. 0050/034090 solid-particle bed, the reaction mixture being maintained in the form of a powder The polymerization tempera-ture was 75C. The acetone was evaporated conti~uous-ly from the polymerization zone 1~5 kg of freshly formed virtually solvent-free copolymer were obtained, the product having a K value of 80 (de-termined in 5%
strength NaCl solution) and a particle diameter of from 1 to 5 mm.
Preparation of polyvinylpyrro7idone 1,500 g of a dry polyvinylpyrrolidone powder having a particle diameter of from 1 to 2 mm were intro-duced into the polymerization apparatus described in Example 1. The oilbath was brought to 90C. A
30% s~rength solution of N-vinylpyrrolidone in cyclohex-ane was then combined with an initiator solution, ~mely a 5% strength solution of azodiisobutyronitrile in cyclo-hexane 3 in a volumetric flow ratio o~ 10:1 in a static mixer, and the mixture of monomer and-polymerization initiator was sprayed continuously, over a period of 5 hours, onto the constantly agi-tated solid particle bed.
The polymerization temperature was 85C. During the polymerization 7 the cyclohexane was removed continuously ~rom the polymerization zone under slightly reduced pressure. A polyvinylpyrrolîdone powder which had a K value o~ 60 (determined in 5% strength NaCl solution) and a particle diameter of from 0.1 to 4 mm was obtained.
This product gave a clear solution in water.
- 22 - O.Z. 0050/034090 ~ LE 11 Prepara~ion of a copolymer of'N-vinylpyrrolidone and vinyl acetate 19500 g of a polyvinylpyrrolidone powder having a particle diameter of from 1 to 2 mm were i~troduced into the polymerization apparatus described in Example 1.
The oilbath was brought to 90C. A 30% strength solution of 80% of N-vinylpyrrolidone and 20% of vinyl acetate in hexane, and an initiator solution, namely a 5~0 strength solution of azodiisobutyronitrile in hexane, were combinedg in a volumetric flow ratio of 10:1, by means of a static mixer, and sprayed progressively, over a period of 5 hours, onto the agitated solid-particle bed, During the polymerization, the reaction mixture was maintained in the form of a powder and the hexane was continuously evaporated from the polymerization z3ne.
The polymerization temperature was 70C, A copolymer powder having a K value of 70 (determined in 5% strength NaCl solution) and a particle diameter of from 0,1 to
During the polymerization, the reaction mixture was main-tained in the form of a powder and the acetone was con-tinuously removed from the polymerization zone by evaporation.
The polymerization temperature was 75C. A virtually non-hydrolyzed polyacrylamide was obtained, which was com~le-tely soluble in water and had a K value of 67.
The par-ticle diameter of the polymer was from 0.1 to 2 mm.
~9~6~
~ 18 - o~ ooSo/o34o9o Aqueous solutions of the copolymer were used as a paper strengthener.
Preparation of polyacrylamide The polymerization apparatus used was a steel pressure kettle which was equipped with a spiral stirrer and had a capacity of 40 liters. The solution of the monomer and the solution of the polymerization initia-tor were mixed in a temperature-controlled spray lance and the mixture was sprayed onto the inert material, in powder form, which had first been introduced into the pressure kettle. The powder formed during thepolymeri-zation wa~s discharged from the polymerization zone by means of a screw.
15 kg o~ polyacrylamide, having a K value of 53 and a particle diameter of from 1 to 4 mm were ~irst introduced into the pressure kettle. The temperature of the heating was set to 80C. 8 liters per hour of a 25% strength solution o~ acrylamide in acetone and 600 ml/hour of a solution in acetone of 0.18 mole % of bis-(4-tert.-butyl-cyclohexyl) peroxydicarbonate and 0.072 mole% of tert~-butyl peroctoate, the percentages being based on acryl-amide~ were then combined by means of a static mixerg and the mixture of the monomer and the polymerization initiators was sprayed onto the poly-acrylamide powder bed over 70 hours. During the - 19 - o~z~ 0050~03~090 polymerization, the reaction mixture was maintained in the form of a powder and the acetone was removed com-pletely from the reaction chamber, as vapor, due to the heat of polymeriza-tion and the energy introduced by stir-ring. The polymer powder formed during the polymeri-zation was discharged by means of a screw. The poly-merization temperature was 75C. 150 kg of freshly formed polymer, having a particle diameter of from 0.1 to 5 mm and a K value of 62 (determined in 0 2% strength aqueous solution) were obtained.
15 kg of polyacrylamide having a K value of 53 and a particle diameter of from 1 to 4 mm were introduced into the continuous polymerization apparatus described in Example 7. The heating of the pressure kettle was set to &oc. 8 liters per hour of a 25~ strength solution of acrylamide in acetone, containing 5~ of water, and 500 ml per hour of an initiator solution in acetone containing 0 15 mole % of bis-(4-tert. butylcyclohexyl) p~rôxydicarbonate, 0.06 mole % of tert.-butyl peroctoate and 0 024 mole % of dibenzoyl peroxide, the percentages being based on acrylamide, were combined by means of a static mixer, and the mixture was sprayed, over a period of 70 hours,onto the solid-particle powder bed. During the polymerization, the bed was circulated continuously and the solvent, as well as the water introduced with the solvent into the polymeri-- 20 ~ O~Z~ 0050/034090 zation zone, were evaporated continuously, thereby main-taining the reaction mixture in the form of a powder during the polymerization. The polymerization temp~rature was 75C. 150 kg of freshly formed poly-acrylamide were obtained; this material was solvent-free and had a K value of 87 (determined in 0 2% strength aqueous solution) and a residual monomer content of 0.9%.
20 kg of this polyacrylamide were subjected to a final polymerization by heating for 4 hours at 110C~
which caused the decomposition of the polymerization initiators (tert.-butyl peroctoate and dibenzoyl perox-ide) present in the product. The residual monomer content fell to about 0.1%, the K value of the product being 86.
Preparation of a copolymer of 80% of acrylamide and 20~o o~ acrylic acid 15 kg of polyacrylamide having a K value of 5~
of 53 and a particle diameter of from 1 to 4 mm were introduced into the polymerization apparatus described in Example 7. The protective heating of the kettle wa~ set to 80Co 8 liters per hour of a 25% strength . solution o~ 80% of acrylamide and 20~ of acrylic acid in acetone and 700 ml per hour of an initiator solution in ace-tone of 0.21 mole %of bis-(4 tert.-butylcyclohexyl peroxydi-carbonate and 0.084 mole % o~ tert.-butyl peroc-toate 9 the percentages being based on monomer mixturet were then combined by means o~ a s-tatic mixer, and the mixture was sprayed 9 over 6~ hours, onto the 6~
- 2~ - O.Z. 0050/034090 solid-particle bed, the reaction mixture being maintained in the form of a powder The polymerization tempera-ture was 75C. The acetone was evaporated conti~uous-ly from the polymerization zone 1~5 kg of freshly formed virtually solvent-free copolymer were obtained, the product having a K value of 80 (de-termined in 5%
strength NaCl solution) and a particle diameter of from 1 to 5 mm.
Preparation of polyvinylpyrro7idone 1,500 g of a dry polyvinylpyrrolidone powder having a particle diameter of from 1 to 2 mm were intro-duced into the polymerization apparatus described in Example 1. The oilbath was brought to 90C. A
30% s~rength solution of N-vinylpyrrolidone in cyclohex-ane was then combined with an initiator solution, ~mely a 5% strength solution of azodiisobutyronitrile in cyclo-hexane 3 in a volumetric flow ratio o~ 10:1 in a static mixer, and the mixture of monomer and-polymerization initiator was sprayed continuously, over a period of 5 hours, onto the constantly agi-tated solid particle bed.
The polymerization temperature was 85C. During the polymerization 7 the cyclohexane was removed continuously ~rom the polymerization zone under slightly reduced pressure. A polyvinylpyrrolîdone powder which had a K value o~ 60 (determined in 5% strength NaCl solution) and a particle diameter of from 0.1 to 4 mm was obtained.
This product gave a clear solution in water.
- 22 - O.Z. 0050/034090 ~ LE 11 Prepara~ion of a copolymer of'N-vinylpyrrolidone and vinyl acetate 19500 g of a polyvinylpyrrolidone powder having a particle diameter of from 1 to 2 mm were i~troduced into the polymerization apparatus described in Example 1.
The oilbath was brought to 90C. A 30% strength solution of 80% of N-vinylpyrrolidone and 20% of vinyl acetate in hexane, and an initiator solution, namely a 5~0 strength solution of azodiisobutyronitrile in hexane, were combinedg in a volumetric flow ratio of 10:1, by means of a static mixer, and sprayed progressively, over a period of 5 hours, onto the agitated solid-particle bed, During the polymerization, the reaction mixture was maintained in the form of a powder and the hexane was continuously evaporated from the polymerization z3ne.
The polymerization temperature was 70C, A copolymer powder having a K value of 70 (determined in 5% strength NaCl solution) and a particle diameter of from 0,1 to
4 mm was obtained. Aqueous solutions of the copoly-mer were used as a hair strengthener, Preparation of a copolymer of styrene and acrylic acid 1,500 g of nylon granules of particle diameterfrom 1 to 2 mm were introduced into the apparatus9 described in Example 1, for the batchwise preparation of polymer powders, The oilbath was brought to 90C, A solution of 600 g of styrene and 200 g of acrylic acid in 2,5 liters of cyclohexane, and a solution of 20 g of 6~
- 23 - o~z~ 0050/034090 an initiator, namely lauroyl peroxide 9 in 250 ml of cyclohexane were then combined, in a volumetric flow ratio of 10:1, by means of a static mixer, and the mix-ture was sprayed, over 4 hours, onto the agitated solid-particle bed~ During the polymerization, the material in the polymerization zone was maintained in the form of a powder and the solvent was removed from the polymeri-zation zone by evaporation. The polymerization temperature was 85C. A copolymer having a K value lo of 50 and an acid number of 350 was obtainedO The particle diameter of the copolymer was from 0.5 to 3 mm.
The copolymer was useful as a binder for road-marking processes, and as a metal-coating agent.
- Preparation of polyacrylic acid 1,500 g of nylon granules of particle diameter from 1 to 2 mm were introduced into the apparatus des-cribed in Example 1 and the oilbath was brought -to 90C.
A solution of 1,200 g of acrylic acid in 4 liters of cyclohexane was then combined with a solution of 10 g of initiator, namely tert.-butyl perpivalate~ in 400 ml of cyclohexane, in a volumetric flow ratio of 10:1, by means of a s-tatic mixer, and the mixture of acrylic acid and polymerization initiator in cyclohexane was sprayed, over 5 hours, onto the constantly circulated solid-particle bed. The polymerization temperature was ~0C. During the pol~merization, the sol~ent was continuously evapora-ted from the polymerization zone.
Polyacrylic acid having a K value of 105 (de-termined in - 24 - o~ zo 0050/034090
- 23 - o~z~ 0050/034090 an initiator, namely lauroyl peroxide 9 in 250 ml of cyclohexane were then combined, in a volumetric flow ratio of 10:1, by means of a static mixer, and the mix-ture was sprayed, over 4 hours, onto the agitated solid-particle bed~ During the polymerization, the material in the polymerization zone was maintained in the form of a powder and the solvent was removed from the polymeri-zation zone by evaporation. The polymerization temperature was 85C. A copolymer having a K value lo of 50 and an acid number of 350 was obtainedO The particle diameter of the copolymer was from 0.5 to 3 mm.
The copolymer was useful as a binder for road-marking processes, and as a metal-coating agent.
- Preparation of polyacrylic acid 1,500 g of nylon granules of particle diameter from 1 to 2 mm were introduced into the apparatus des-cribed in Example 1 and the oilbath was brought -to 90C.
A solution of 1,200 g of acrylic acid in 4 liters of cyclohexane was then combined with a solution of 10 g of initiator, namely tert.-butyl perpivalate~ in 400 ml of cyclohexane, in a volumetric flow ratio of 10:1, by means of a s-tatic mixer, and the mixture of acrylic acid and polymerization initiator in cyclohexane was sprayed, over 5 hours, onto the constantly circulated solid-particle bed. The polymerization temperature was ~0C. During the pol~merization, the sol~ent was continuously evapora-ted from the polymerization zone.
Polyacrylic acid having a K value of 105 (de-termined in - 24 - o~ zo 0050/034090
5% strength NaC1 solution) and a particle diameter of from 0.5 to 3 mm was ob-tained. The polymer was use-ful as a thickener in print pastes.
Preparation of ammonium polyacrylate 1,500 g of nylon granules of particle diameter from l to 2 mm were introduced into the apparatus des-cribed in Example l and the oilbath was brought to 75C.
A solution of 1,000 g of acrylic acid in 3,000 g of methyl tert.-butyl ether and a sol.ution of 16.6 g of an initiator9 namely bis-(4-tert.-butylcyclohexyl) peroxy-dicarbonate, in 500 ml of methyl tert.-butyl ether were then combined, in a volumetric flow ratio of lO:l,bymeans of astatic mixer and the resulting mixturewasspraye~ over 5 hours, onto the constantly circulating solid-particle bed. The polymerization temperature was 75C. An atmosphere of ammonia was maintained in the reactor.
During the polymerization, the reaction mixture was main-tained in the form of a pcwder and the methyl tert.-butyl ether was removed completely, as vapor, from the reaction chamber, due to the heat of polymerization, the heat of neutralization and the energy introduced by stirring.
Ammonium polyacrylate having a K value of 127.3 (measured on an O.l~o strength solution in 5% strength NaCl solution) and a particle dlameter of from 0.1 to 2 mm was obtainedO
Preparation of ammonium polyacrylate 1,500 g of nylon granules of particle diameter from l to 2 mm were introduced into the apparatus des-cribed in Example l and the oilbath was brought to 75C.
A solution of 1,000 g of acrylic acid in 3,000 g of methyl tert.-butyl ether and a sol.ution of 16.6 g of an initiator9 namely bis-(4-tert.-butylcyclohexyl) peroxy-dicarbonate, in 500 ml of methyl tert.-butyl ether were then combined, in a volumetric flow ratio of lO:l,bymeans of astatic mixer and the resulting mixturewasspraye~ over 5 hours, onto the constantly circulating solid-particle bed. The polymerization temperature was 75C. An atmosphere of ammonia was maintained in the reactor.
During the polymerization, the reaction mixture was main-tained in the form of a pcwder and the methyl tert.-butyl ether was removed completely, as vapor, from the reaction chamber, due to the heat of polymerization, the heat of neutralization and the energy introduced by stirring.
Ammonium polyacrylate having a K value of 127.3 (measured on an O.l~o strength solution in 5% strength NaCl solution) and a particle dlameter of from 0.1 to 2 mm was obtainedO
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the preparation of a polymer powder from polymerizable monoethylenically unsaturated com-pounds which boil at above +5°C under 1,013 mbar, which comprises introducing the monomers, in the form of solu-tions or emulsions, of from 5 to 50% strength, in an inert organic solvent which is a precipitant for the polymer, into a powder bed under polymerization con-ditions, and polymerizing the monomers in the said bed in the presence of a conventional polymerization initiator, whilst maintaining the reaction mixture in the form of a powder and causing it to circulate, the organic solvent being distilled from the polymerization zone during the polymerization.
2, A process as claimed in claim 1, wherein the monomers employed are water-soluble, ethylenically un-saturated compounds which form hydrophilic polymers.
3. A process as claimed in claim 1, wherein the monomers employed are water-insoluble.
4. A process as claimed in claim 1 or 2 , where-in a mixture of polymerization initiators, which differ by at least 20°C in the temperature at which their de-composition has a half-life of 1 hour, is employed, the mixture containing from 0.1 to 5 mole %, based on mono-mers, of the polymerization initiator having the lower decomposition temperature and from 0.05 to 0.8 mole %, based on monomers, of the polymerization initiator having the higher decomposition temperature.
5. A process as claimed in claim 1 or 2, wherein, following the main polymerization, a polymeri-zation initiator which decomposes at a higher temperature than does the initiator used for the main polymerization is added, and the final polymerization is carried out at from 10 to 100°C
above the temperature at which the main polymerization has been carried out.
above the temperature at which the main polymerization has been carried out.
6. A process as claimed in claim 2, wherein the monomers employed comprise at least one ethylenically unsaturated com-pound selected from the group consisting of an ethylenically unsaturated C3-C5-monocarboxylic acid, dicarboxylic acid or anhydride thereof, an amide of an ethylenically unsaturated carboxylic acid, a basic acrylamide or methacrylamide, an ester of an ethylenically unsaturated carboxylic acid with an amino-alcohol, vinylimidazole, a substituted vinylimidazole and a vinylsulfone.
7. A process as claimed in claim 1, wherein the monomers are water-insoluble.
8. A process as claimed in claim 7, wherein said water insoluble monomers are styrene, acrylonitrile, methacrylonit-rile, esters of acrylic acid or methacrylic acid with C1-C8 alcohols, vinyl esters of C2-C12 carboxylic acids, and mono-esters or di-esters of maleic acid of vinyl esters.
9. A process as claimed in claim 1, wherein said organic solvent is a ketone, a saturated aliphatic hydrocarbon, a cyclic aliphatic hydrocarbon, an aromatic hydrocarbon, an aliphatic halohydrocarbon, an ether, an ester, an alcohol, a lactone, dimethylsulfoxide, dimethylformamide or nitromethane.
10. A process as claimed in claim 1, wherein said organic solvent contains up to 10% by weight of water.
11. A process as claimed in claim 1, wherein said emulsions are prepared by emulsifying said monomers with an emulsifier selected from the group consisting of a fatty acid ester of sorbitol, an ethylene oxide/propylene oxide copolymer, an oxy-ethylated fatty acid, a phenol, a C10-C8 alcohol and a C10-Cl8 amine.
12. A process as claimed in claim 11, wherein said emulsifier is present in an amount of from 0.01 to 1% by weight, based on said monomers.
27.
27.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19792941978 DE2941978A1 (en) | 1979-10-17 | 1979-10-17 | METHOD FOR PRODUCING POWDER-SHAPED POLYMERISATS |
| DEP2941978.1 | 1979-10-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1194648A true CA1194648A (en) | 1985-10-01 |
Family
ID=6083682
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000362436A Expired CA1194648A (en) | 1979-10-17 | 1980-10-15 | Preparation of polymer powders |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0027936B1 (en) |
| JP (1) | JPS5665003A (en) |
| AT (1) | ATE5078T1 (en) |
| CA (1) | CA1194648A (en) |
| DE (2) | DE2941978A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5010150A (en) * | 1988-12-15 | 1991-04-23 | Basf Aktiengesellschaft | Controlling the particle size in the preparation of polymer powders |
| US5084535A (en) * | 1988-12-15 | 1992-01-28 | Basf Aktiengesellschaft | Preparation of pulverulent polymers of acrylic and/or methacrylic acid and use thereof |
| US5977274A (en) * | 1998-03-09 | 1999-11-02 | National Starch And Chemical Investment Holding Corporation | Method for making polymers from N-vinyl formamide monomer |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2090602B (en) * | 1981-01-06 | 1984-08-15 | Mitsubishi Rayon Co | Polymer composition |
| EP0113048B1 (en) * | 1982-12-04 | 1986-06-11 | BASF Aktiengesellschaft | Process for preparing powdery polymers, and their use |
| DE3434137A1 (en) * | 1984-09-18 | 1986-03-20 | Basf Ag, 6700 Ludwigshafen | METHOD FOR THE PRODUCTION OF INSOLUBLE, LITTLE SWELLABLE POWDER-SHAPED POLYMERS |
| DE3434138A1 (en) * | 1984-09-18 | 1986-03-27 | Basf Ag, 6700 Ludwigshafen | METHOD FOR THE PRODUCTION OF INSOLUBLE, LITTLE SWELLABLE POWDER-SHAPED POLYMERS |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2636243C2 (en) * | 1976-08-12 | 1985-12-19 | Basf Ag, 6700 Ludwigshafen | Process for the production of powdery polymers |
-
1979
- 1979-10-17 DE DE19792941978 patent/DE2941978A1/en not_active Withdrawn
-
1980
- 1980-10-10 EP EP80106166A patent/EP0027936B1/en not_active Expired
- 1980-10-10 DE DE8080106166T patent/DE3065385D1/en not_active Expired
- 1980-10-10 AT AT80106166T patent/ATE5078T1/en active
- 1980-10-15 CA CA000362436A patent/CA1194648A/en not_active Expired
- 1980-10-17 JP JP14452380A patent/JPS5665003A/en active Granted
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5010150A (en) * | 1988-12-15 | 1991-04-23 | Basf Aktiengesellschaft | Controlling the particle size in the preparation of polymer powders |
| US5084535A (en) * | 1988-12-15 | 1992-01-28 | Basf Aktiengesellschaft | Preparation of pulverulent polymers of acrylic and/or methacrylic acid and use thereof |
| US5977274A (en) * | 1998-03-09 | 1999-11-02 | National Starch And Chemical Investment Holding Corporation | Method for making polymers from N-vinyl formamide monomer |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0027936B1 (en) | 1983-10-19 |
| DE2941978A1 (en) | 1981-04-30 |
| JPS5665003A (en) | 1981-06-02 |
| ATE5078T1 (en) | 1983-11-15 |
| JPH0224841B2 (en) | 1990-05-30 |
| EP0027936A1 (en) | 1981-05-06 |
| DE3065385D1 (en) | 1983-11-24 |
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