JPH05125109A - Preparation of powdery polymer of hydrolyzed n-vinylformamide and dehydrating agent, retaining agent and coagulator for paper making - Google Patents

Abstract

PURPOSE: To obtain a polymer for a dewatering agent, a retaining agent, and a coagulant for paper making, etc., by a process in which N-vinyl formamide units are polymerized/introduced to be incorporated into a powdery polymer having a specified water content, which is hydrolyzed with an acid or base in an inactive suspending agent.

CONSTITUTION: When N-vinyl formamide units is polymerized/introduced to be incorporated in a powdery polymer, which is hydrolyzed in the presence of an acid or base in an inactive suspending agent, the hydrolyzed polymer is isolated, and the hydrolyzed powdery polymer of N-vinyl formamide having units exhibited by a formula, the water content of the polymer is at least 6-90 wt.% at the beginning of hydrolysis, after the hydrolysis, the hydrolyzed polymer is treated with a finely divided inorganic solid to obtain the intended hydrolyzed powdery polymer of N-vinyl formamide which is useful as a dewatering agent, a retaining agent, and a coagulant for paper making.

COPYRIGHT: (C)1993,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention hydrolyzes a powdery polymer containing N-vinylformamide units by polymerizing and introducing the same, in the presence of an acid or a base in an inert suspension agent. The isolated powdery polymer
-A method for producing a hydrolyzed powdery polymer of vinylformamide.

[0002]

2. Description of the Prior Art From US Pat. No. 4,421,602 is known the preparation of hydrolyzed polymers of N-vinylformamide. According to the method described therein, poly-
In the presence of an acid or a base, an aqueous solution of N-vinylformamide is used.
It is hydrolyzed to such an extent that it contains 0 mol%. The aqueous or alcoholic solution of the partially hydrolyzed poly-N-vinylamide thus obtained is used directly, for example as a dewatering aid in papermaking or as a coagulant for wastewater sludge.

From US Pat. No. 4,623,699,
It is known to prepare hydrolyzed powdered polymers of N-vinylformamide by reacting gaseous hydrogen halides onto poly-N-vinylformamide powders having a water content of up to 5% by weight. .. The hydrolysis is advantageously up to 2. with gaseous hydrogen chloride or hydrogen bromide.
It is carried out in the presence of 5% by weight of water or in the absence of water.
Hydrolysis of the powdered polymer can also be carried out in suspending agents such as dioxane, tetrahydrofuran or cyclohexane. This method has the disadvantage that a considerable amount of hydrogen chloride gas is removed from the reaction zone with the exhaust gas together with the carbon monoxide produced by the hydrolysis. Another significant drawback of this method is the heterogeneity of the resulting hydrolyzed powdery polymer. The outer part of the powder particles is mostly present in hydrolyzed form, ie as polyvinylamine, whereas the inner part of the powder particles consists of unhydrolyzed polyvinylformamide. It is due to the fact that hydrogen chloride gas diffuses relatively slowly into the hard polymer particles. A relatively long dissolution time is required for producing a dilute aqueous solution from the hydrolyzed powdery polymer.

It is known from EP-A-0262577 that poly-N-vinylformamide can be hydrolyzed in aqueous solution with bases or acids. The acid or base required for hydrolysis can also be added to the water-in-oil polymer emulsion as described in the specification. However, at that time, the emulsion is decomposed by the addition of a base or an acid, so that the hydrolyzed powdery poly-N is used.
-No vinylformamide is obtained.

[0005]

It is an object of the present invention that the particles are hydrolyzed as completely as possible, which is faster than the heterogeneous polymer particles of the same composition described in the prior art. A method for producing a hydrolyzed powdery polymer of N-vinylformamide, which gives a polymer soluble in water.

[0006]

According to the present invention, this object is achieved when the water content of the powdery polymer to be hydrolyzed is at least 6 to 90% by weight at the beginning of the hydrolysis.
The vinylformamide-units are polymerized to contain a powdery polymer which is hydrolyzed in the presence of an acid or a base in an inert suspending agent, and the hydrolyzed powdery polymer is isolated to give the formula :

[0007]

[Chemical 2]

This is solved by a method for producing a hydrolyzed powdery polymer of N-vinylformamide containing units of Advantageously, the water content of the polymer is from 10 to 65% by weight at the beginning of the hydrolysis.

The process according to the invention starts from a powdered polymer which contains N-vinylformamide units polymerized in. The production of polymers of this kind is known, for example, from US Pat. No. 4,623,699. for that reason,
N-vinylformamide can be polymerized by any known polymerization method, either alone or mixed with other ethylenically unsaturated monomers. When the polymerization is carried out in a solution, it is naturally necessary to remove the solvent in order to obtain a powdery polymer. The polymerization can be carried out in alcohols such as methanol, ethanol, isopropanol or n-propanol or mixtures of these alcohols. At that time, a precipitated polymer is obtained, which can be isolated as a powder by filtering and removing the attached solvent. However, it is advantageous to use polymers such as are obtained by the method of inverse suspension polymerization. This method is known, for example, from US Pat. No. 2,982,749. In the inverse suspension polymerization method, generally, a water-soluble monomer is polymerized in the form of a water-in-oil emulsion which is stabilized with a protective colloid. To produce polymers containing N-vinylformamide units, N-vinylformamide is used as the only monomer to produce homopolymers, or this monomer is used in combination with other ethylenically unsaturated monomers. Polymerize with the monomer. The monomers mentioned for producing the copolymer can be classified into various groups. Examples of the group (a) of comonomers include ethylenically unsaturated C ₃ −.
-C ₆ - carboxylic acid, its formula:

[0010]

[Chemical 3]

[Wherein R = C ₂ -C ₅ -alkylene,
R ¹ , R ² , R ³ = H, CH ₃ , C ₂ H ₅ , C ₃ H ₇ ] with amides and esters with amino alcohols. These compounds include, for example, acrylic acid, methacrylic acid,
Crotonic acid, itaconic acid, maleic acid, fumaric acid, acrylamide, methacrylamide, crotonic acid amide, N
-Alkyl acrylamide, N-alkyl methacrylamide, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, dimethylaminopropyl acrylate, dimethylaminobutyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, dimethylamino neopentyl methacrylate are suitable. Basic acrylates and methacrylates are used in the form of salts with strong mineral acids or carboxylic acids or in the quaternized form. Anion X ⁻ of the compound of formula II
Is methosulfate, ethosulfate or halogen from a mineral acid or carboxylic acid residue or quaternizing agent,
The pH value should then preferably not be set below 4.

Other water-soluble comonomers of group (a) are
N-vinylpyrrolidone, N-vinylcaprolactone, acrylamidopropanesulfonic acid, vinylphosphonic acid,
Vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, styrene sulfonic acid and acrylic acid- (3-sulfopropyl) ester. The olefinically unsaturated carboxylic acids are generally used in the polymerization either partially or in a neutralized form up to 100% in order to maintain exactly the pH value of 4-9, preferably 5-8.

Water-soluble monomers of group (a) include diallylammonium compounds such as dimethyldiallylammonium chloride, diethyldiallylammonium chloride or diallylpiperidinium bromide, N-vinylimidazolium compounds such as N-vinylimidazole and Salts of quaternized products of 1-vinyl-2-methyl-imidazole and N-vinylimidazolines, such as N-vinylimidazoline, 1-vinyl-2-methyl-imidazoline, 1-vinyl-2-ethylimidazoline or 1- Vinyl-2-n-propyrimidazolines, which are likewise used in the polymerization as quaternized forms or salts, are also suitable.

Other groups of monomers (a) which are completely or only partially soluble in water but are copolymerized with N-vinylformamide include, for example, the hydroxy groups of acrylic acid and methacrylic acid. Alkyl esters, for example
Among these are 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate and hydroxyethyl methacrylate and hydroxypropyl methacrylate. These groups of monomers that are copolymerized with N-vinylformamide include:
For example, acrylonitrile and methacrylonitrile, vinyl acetate, vinyl propionate and 2 carbon atoms.
N-vinylcarboxylic amides derived from carboxylic acids having up to 6 such as N-vinylalkylformamides such as N-vinyl-N-methylformamide and N-vinylacetamide and N-vinyl-N-methylacetamide. Belong to Hydroxyalkyl (meth)
Acrylate, vinyl acetate, acrylonitrile,
Methacrylonitrile as well as N-alkyl (meth) -acrylamide are used in copolymerization in amounts such that the monomer mixture is still soluble in water. The ethylenically unsaturated carboxylic acids, sulphonic acids and phosphonic acids should be used in the partially or completely neutralized form of the polymerization. For neutralization, alkali metal bases such as sodium hydroxide solution, potassium hydroxide solution or ammonia are used.

Advantageously, as monomers in the copolymerization with N-vinylformamide, acrylic acid, methacrylic acid, acrylamide, N-vinylpyrrolidone, acrylamidomethanepropanesulphonic acid and vinylacetate, either alone or in their single form. Used in a mixture of mers. The copolymer should contain at least 20% by weight, preferably at least 40% by weight and particularly preferably 60% by weight, of N-vinylformamide, introduced in a polymerized manner. The monomers of group (a) account for up to 80% by weight, preferably up to 40% by weight, in the structure of the copolymer.

The polymerization of N-vinylformamide and the monomer of group (a) can also be carried out in the presence of a monomer of group (b), a so-called crosslinking agent. The crosslinker has at least two non-covalently bonded ethylenically unsaturated double bonds. Suitable cross-linking agents are, for example, N, N'-methylene-bisacrylamide, polyethylene glycol diacrylate and polyethylene glycol dimethyl acrylate derived from polyethylene glycol each having a molecular weight of 126-8500, trimethylolpropane triacrylate, trimethylolpropane triacrylate. Methacrylate, ethylene glycol diacrylate, propylene glycol diacrylate, butanediol diacrylate, hexanediol diacrylate, hexanediol methacrylate, diacrylates and dimethacrylates of block copolymers from ethylene oxide and propylene oxide, 2 or 3 acrylics Polyhydric alcohols esterified with acid or methacrylic acid, such as glycerin or pentaerythritol, thoria Triethanolamine, a tetraallylethylenediamine, divinylbenzene, diallyl phthalate, polyethylene glycol divinyl ether, trimethylolpropane diethyl ether, butanediol divinyl ether, pentaerythritol triallyl ether and / or divinylethyleneurea. Preference is given to water-soluble crosslinking agents such as N, N'-methylenebisacrylamide, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, pentaerythritol triallyl ether and / or divinyl urea.
If a cross-linking agent is used, it is used in an amount of 0.001-5, preferably 0.01-2% by weight, based on the monomer mixture.

The polymerization can optionally be carried out in the presence of customary polymerization regulators. Suitable polymerization regulators are, for example, thio compounds such as thioglycolic acid, mercapto alcohols such as 2-mercaptoethanol, mercaptopropanol and mercaptobutanol, dodecyl mercaptan, formic acid and ammonia, allyl compounds such as allyl alcohol and butenol.

As the inert hydrophobic liquid, virtually all liquids which are immiscible with water which do not participate in the polymerization can be used in the inverse suspension polymerization. Advantageously, in inverse suspension polymerization, aliphatic and aromatic hydrocarbons or mixtures of aliphatic and aromatic hydrocarbons are used. Suitable aliphatic hydrocarbons are, for example, pentane, hexane, heptane, octane, nonane, decane, cyclohexane, decalin, methylcyclohexane, isooctane and ethylcyclohexane. Aromatic hydrocarbons used as inert hydrophobic liquids in inverse suspension polymerization are, for example, benzene, toluene, xylene and isopropanol. Further, of course, halogenated hydrocarbons such as tetrachloroethane,
Hexachloroethane, trichloroethane and chlorobenzene can also be used. Cyclohexane and aromatic hydrocarbons with a boiling range of 60 to 120 ° C. are preferably used.

In order to disperse the aqueous monomer solution in the inert hydrophobic liquid, a protective colloid is needed which has the task of stabilizing the suspension of the aqueous monomer solution in the inert hydrophobic liquid. The protective colloid further affects the particle size of polymerized particles produced by the polymerization.

As protective colloids, it is possible to use, for example, the substances as described in US Pat. No. 2,982,749. Furthermore, West German Patent No. 2634486 obtained, for example, by reacting an oil and / or a resin each having an allylic hydrogen atom with maleic anhydride
The protective colloids known from the specification are suitable.

Other protective colloids are known, for example from the German patent DE 2710372, which comprises 60-99.9% by weight of dicyclopentadiene, 0-30% by weight of styrene and 0.1-0.1% of maleic anhydride. Obtained by thermal and radical solution- and suspension polymerization from 10% by weight.

Further, as a protective colloid, US Pat.
The graft polymers known from 79361 are suitable, which are (a) monovinylaromatic monomers 40-1.
00% by weight, (b) 0 to 60% by weight of monoethylenically unsaturated carboxylic acid having 3 to 6 C atoms, maleic anhydride and / or itaconic anhydride, (c) other monoethylenically unsaturated monomer Polymer (A) consisting of 0 to 20% by weight
[At that time, the sum of the weight percentages of (a) to (c) is always 100.
And the polymer (A) has a molecular weight (number average) of 500 to 20.
000 and iodine hydride (according to DIN 53241)
1.3 to 51], (1) Acrylic ester and / or methacrylic ester 7 of monohydric alcohol containing 1 to 20 C atoms.
0 to 100% by weight, (2) monoethylenically unsaturated carboxylic acid having 3 to 6 C atoms, maleic anhydride and / or itaconic anhydride 0
˜15% by weight, (3) 0 to 10% by weight of acrylic acid monoester and / or methacrylic acid monoester of at least dihydric alcohol (4) 0 to 15% by weight of monovinyl aromatic monomer, and (5) acrylamide and / Or methacrylamide 0
7.5% by weight of the monomer mixture [there is that the total of the% by weight of (1) to (5) is always 100] and an inert hydrophobic diluent at temperatures up to 150 ° C. In the presence of a polymerization initiator in which the monomer is present in an amount of 97.5 to 50% by weight, based on the mixture of the polymer (A) and the monomer. use.

When an aliphatic hydrocarbon is used as an inert hydrophobic liquid in the inverse suspension polymerization, protective colloids are prepared from inorganic suspending agents based on modified finely divided minerals and nonionic surfactants. The resulting mixtures have proven to be very advantageous. This type of protective colloid is described in US Pat. No. 473.
9009 specification.

Inorganic suspending agents having a low hydrophilic-lipophilic balance are conventional agents in the inverse suspension polymerization process. The mineral component of this drug is, for example, bentonite, montmorillonite or kaolin. To modify finely divided minerals,
Amine of long chain, e.g., C ₈ -C ₂₄ - is treated with an amine salt or quaternary ammonium salt, whereby the embedding cause the amine salt or quaternary ammonium salt to the individual layers of the subdivision like mineral. The optionally quaternized ammonium salts used for modification are preferably C ₁₀ -C ₂₂ -alkyl radicals 1.
Contains ~ 2. Other substitutions on the ammonium salt are C ₁ -C ₄ -alkyl or hydrogen. The maximum content of free ammonium salt of amine-modified mineral is 2% by weight
Is. Granular minerals modified with ammonium salts are commercially available.

Inorganic suspending agents for inverse suspension polymerization also include silicon dioxide reacted with organosilicon compounds. A suitable organosilicon compound is, for example, trimethylsilyl chloride.

The purpose of the modification of the inorganic finely divided minerals is to improve the wettability of the minerals with the aliphatic hydrocarbons used as the outer phase of the inverse suspension polymerization. Natural minerals applied in layers, such as bentonite and montmorillonite, can be modified with amines to swell the modified minerals in aliphatic hydrocarbons, precipitating very fine particles. .. The particle size is about 1 μm, generally in the range 0.5-5 μm. Silicon dioxide reacted with an organosilicon compound has a particle size in the range of about 10-40 nm. The modified finely divided mineral is moistened with an aqueous monomer solution or solvent, thereby embedding in the phase boundary between the aqueous phase and the organic phase. This prevents aggregation when two aqueous monomer droplets in suspension collide, i.e.
Prevents sticking of polymer particles.

The stability of a water-in-oil suspension containing a modified finely divided mineral as a suspending agent and an aliphatic hydrocarbon as an oil phase is between 0.1 and 0.1 with respect to the monomers used. 5% by weight
The addition of the nonionic surfactant of No. 2 does not cause the batch to agglomerate or condense in the polymerization.

Nonionic surfactants used with finely divided minerals in the process of inverse suspension polymerization have HLB values of 2 to 16 [The definition of HLB value is W. C. Griffin
, J. Soc. Cosmetic Chem. , Fifth
Vol., 249 (1954)]. Suitable nonionic surfactants are, for example, C ₈ -C ₁₂ -alkylphenols alkoxylated with ethylene oxide and / or propylene oxide. For example, octyl- or nonylphenol reacted with 4 to 20 mol of ethylene oxide per mol of phenol is commercially available. Other nonionic surfactants used are ethoxylated C ₁₀ -C ₂₄ - fatty alcohols and / or C ₁₀ -C ₂₄ - polyhydric partially esterified with a fatty acid C ₃ -C ₆ - It is alcohol. These can additionally be reacted with 2 to 20 mol of ethylene oxide. Preferable examples of the aliphatic alcohol include palmityl alcohol, stearyl alcohol, myristyl alcohol, lauryl alcohol, oxo alcohol, unsaturated alcohols such as oleyl alcohol. Fatty alcohols are ethoxylated to the extent that they are soluble in water. Generally alcohol 1
The moles are reacted with 2 to 20 moles of ethylene oxide, whereby the above-mentioned HLB-containing surfactant is obtained.

Further suitable as surfactants are partially esterified and optionally ethoxylated C ₃ -C ₆ -alcohols. This type of alcohol is, for example,
Glycerin, sorbit, mannite and pentaerythritol. These polyhydric alcohols are C ₁₀ -C ₂₄
-Partially esterified with fatty acids such as oleic acid, stearic acid or palmitic acid. At that time, even if esterification using fatty acid is the best, O of polyhydric alcohol
It should be carried out to the extent that one H group still remains unesterified. Suitable esterification products are, for example, sorbitan monooleate, sorbitan tristearate, mannitol monooleate, glycerin monooleate and glycerin dioleate. Thus, said fatty acid ester of a polyhydric alcohol which still contains at least one free OH group can be reacted with ethylene oxide and / or propylene oxide. 2 to 20 mol of ethylene oxide is used per mol of fatty acid ester. The degree of ethoxylation has an influence on the HLB value of a nonionic surfactant as is known. By appropriately selecting the alkoxylating agent, the HL in the above range can be obtained.
It is possible to produce a surfactant having a B value. The nonionic surfactants can be used in the inverse suspension polymerization either alone or mixed with one another, each as protective colloid in combination with finely divided minerals.

In this case, a number of variations occur, for example the use of surfactants or alkoxylated phenols of varying degrees of ethoxylation together with ethoxylated fatty alcohols or ethoxylated fatty alcohol derivatives. You can also do it. Advantageously, 0.2 to 3% by weight of nonionic surfactant, based on the monomers used in the polymerization, are used to stabilize the suspension.

In addition, monoesters and monoamides of alcohols having 4 to 30 C atoms and primary and secondary amines with molar copolymers of maleic anhydride having 4 to 30 C atoms and olefins, for example: Molecular weight 200
The monoco-stearyl ester of a molar copolymer of maleic acid and diisobutene of 00 is mentioned as the sole protective colloid.

The protective colloid is 0.
It is used in the inverse suspension polymerization in an amount of 01 to 10, preferably 0.05 to 5% by weight.

The polymerization is carried out by customary polymerization initiators such as ammonium disulfate, sodium disulfate and potassium peroxide disulfate, peroxides such as dibenzoyl peroxide, dilauryl peroxide, di-2-ethylhexyl peroxydicarbonate. , Dicyclohexyl peroxydicarbonate, bis (4-t-butylcyclohexyl) -peroxydicarbonate, t-butylperpivalate, t-butylperbenzoate, t-butylpermaleinate, di-t-
Butyl peroxide, t-butyl hydroperoxide,
It is carried out in the presence of hydrogen peroxide and a Ladox catalyst, in which case ammonium ferrous sulfate (II) sulfate, ascorbic acid, sodium methylsulfinate, disodium disulfite and sodium hydrogen sulfite are used as components having a reducing action. Is mentioned. Furthermore, an azo initiator,
For example, azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylnitrile), 2,2'-azobis (N, N'-dimethyleneisobutylamidine) -dihydrochloride, 2,2'- Azobis (2-amidinopropane) -dihydrochloride, 2,2'-azobis (N,
N'-Dimethyleneisobutylaniline), 4,4'-azobis (4-cyanopentanecarboxylic acid) and 2-carbamoylazoisobutyronitrile are preferred. The polymerization initiators can be used alone or in a mixture.

The decomposition rate of peroxide decomposed at high temperature is
The decomposition rate of the peroxide can be adapted to the polymerization temperature selected in each case, since it can be reduced by using together with an organometallic complex compound, for example copper acetylacetonate. The polymerization initiator is 0.01 to 5, preferably 0.2 to 3 with respect to the monomers used in the polymerization.
Used in the amount by weight. Water-soluble initiators are preferably used. In particular, 2,2'-azobis (2-aminopropane) dihydrochloride and 2,2'-azobis (N,
N'-Dimethyleneisobutylamidine) dihydrochloride is preferred. The polymerization is generally carried out in the pH range 4 to 4 in order to prevent hydrolysis of the monomeric N-vinylformamide.
9, preferably 5-8. Therefore, it is advantageously carried out in the presence of a buffer, for example with primary and secondary sodium phosphates.

In many cases, it is advantageous to carry out the polymerization in the presence of complexing agents. Examples include so-called nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid and hydroxyethylethylenediaminetriacetic acid. The alkali metal salt is preferably used here. These are 10 to 5000, preferably 100 to 2
It is added in an amount of 000 ppm.

To polymerize, dissolve the monomer in water,
The monomer concentration in the aqueous solution is 10 to 80% by weight, preferably 3
It is 0 to 70% by weight. The aqueous solution is then emulsified in the aliphatic hydrocarbon. In suspension polymerization, the weight ratio of water to the oil phase is generally 1 to 8: 9 to 2.

The inverse suspension polymerization--like the polymerization--is carried out with exclusion of oxygen, preferably in a nitrogen atmosphere. The polymerization temperature is 25 to 120 ° C. The polymerization can be carried out at reduced pressure or elevated pressure. Most simply, the polymerization is carried out at the boiling temperature of the aliphatic hydrocarbon or aliphatic hydrocarbon mixture used as suspending agent.

The polymerization is carried out by first producing a water-in-oil emulsion from an aqueous monomer solution and an aliphatic hydrocarbon.
At that time, in order to help the dispersion of the aqueous solution in the hydrocarbon oil,
Use protective colloids as suspending agents. At that time, the suspending agent may be added to the aqueous monomer solution or to the aliphatic hydrocarbon. However, the aliphatic hydrocarbon and the suspending agent are pre-charged into the polymerization vessel and then the aqueous monomer solution is added with vigorous stirring so that a water-in-oil emulsion is formed. You can also Then either polymerize or
Alternatively, first, a part of the monomer aqueous solution is dispersed in the aliphatic hydrocarbon, the polymerization is started, and then the monomer aqueous solution is added depending on the progress of the polymerization. At that time, a water-in-oil type polymer suspension is produced through the water-in-oil type monomer emulsion. In this way, the particle size of 1 μm
A burr-like polymer having a diameter of 2 mm, preferably 50 μm to 1 mm, is obtained.

After the polymerization, the burr-like polymer thus obtained is present as swollen particles containing and adsorbing water used in the inverse suspension polymerization. Therefore, the water content of the swollen particles is up to 90% by weight. The polymer produced by the inverse suspension polymerization method can be directly hydrolyzed.
However, it can also be azeotropically dehydrated in advance to a water content of 0 to 65% by weight. The polymer particles are dehydrated to such an extent that they still contain at least 6% by weight of water.

The N-vinylformamide, alone or together with a comonomer, is first polymerized in an aqueous solution, then an inert hydrophobic liquid and a conventional protective colloid (as described in inverse suspension polymerization) in the aqueous solution. It is also possible to carry out the hydrolysis after addition of vigorous stirring and then directly or after partial azeotropic distillation for adjusting the water content according to the invention.

Depending on the polymerization conditions, the purity of the monomers and the use of comonomers, polymers of various molecular weights are obtained, which are characterized by the K value. The Fickencher has a K value of 20 to 300 (measured at a polymer concentration of 0.1% in a 5% saline solution at 25 ° C.).

The polymer has the formula:

[0043]

[Chemical 4]

It contains at least 20 mol% of characteristic units of the formula:

[0045]

[Chemical 5]

The unit can be changed to. Depending on the amount of water contained in the polymer particles and the reaction conditions for hydrolysis, ie the amount of acid or base to the polymer to be hydrolyzed and the reaction temperature in the hydrolysis, the units of formula II of the polymer Partial or complete hydrolysis is obtained. The hydrolysis of the polymer
0.1-10 monomeric units of formula II contained in the polymer
0%, preferably 1 to 60% of these units are hydrolyzed. Hydrolysis temperature is 30-1
It is carried out at 50 ° C., preferably 40-120 ° C. For hydrolysis in the temperature range above the boiling temperature of the solvent or water, the hydrolysis should be carried out in a pressure vessel.

To hydrolyze, first an acid or base is added to the polymer suspension prepared. Suitable acids for hydrolysis are, for example, mineral acids such as hydrogen halides (in gaseous or aqueous solution), sulfuric acid, nitric acid, phosphoric acid, (ortho-, meta-polyphosphoric acid) and organic acids such as C ₁ -C _5. Carboxylic acids such as formic acid, acetic acid and propionic acid or aliphatic or aromatic sulphonic acids such as methanesulphonic acid, benzenesulphonic acid or toluenesulphonic acid. Hydrochloric acid or sulfuric acid is preferably used for the hydrolysis. 0.05 to 1.5, preferably 0. 5, per equivalent of formyl groups in the polymer.
4-1.2 equivalents of acid or base are required.

When hydrolyzing with a base, metal hydroxides of metals of the first and second main groups of the periodic table are used.
For example, lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, strontium hydroxide and barium hydroxide are suitable. However, likewise ammonia and alkyl derivatives of ammonia, such as alkyl-
Alternatively, arylamines such as triethylamine, monoethanolamine, diethanolamine, triethanolamine, morpholine or aniline can also be used. Ammonia, sodium hydroxide solution or potassium hydroxide solution is preferably used as the base for hydrolysis.

The acid or base used as hydrolyzing agent is preferably partially dehydrated in the polymer suspension obtained by inverse suspension polymerization, either immediately after polymerization or by azeotropic distillation to the desired water content. And then add. The swollen polymeric particles are strongly tacky but do not agglomerate or form lumps. Instead, they are present as suspended particles in the suspending agent containing the protective colloid from the time of polymerization. Therefore, according to the present invention, hydrolysis is advantageously 0.01
It is carried out in the presence of protective colloids in an amount of -10% by weight. The protective colloid is then the compound generally used in inverse suspension polymerization. Thus, powdered polymers of N-vinylformamide obtained by methods other than inverse suspension polymerization are advantageously hydrolyzed in the presence of at least one protective colloid of this type.

Since 1 mol of water is used per 1 mol of amide which is saponified by hydrolysis, the maximum saponification degree can be adjusted by the water content in the polymer particles. Thus, for example, with poly-N-vinylformamide, a maximum saponification degree of 43% can only be achieved with a water content of 10%.
A water content of at least 20% in the polymer is required for 100% hydrolysis of the N-vinylformamide pomopolymer. The reaction time for the hydrolysis is 2 to 40 hours, preferably 3 to 10 hours. The reaction achieved is 0.1-100%, preferably 1-60%.

In order to obtain a polymer which is not crosslinked by hydrolysis and is readily soluble in water, the poly-N-vinylformamide used for hydrolysis is obtained because the hydrolysis of N-vinylformamide produces acetaldehyde. It is required to contain virtually no remaining N-vinylformamide monomer. Acetaldehyde causes the crosslinking of highly reactive polyvinylamines. Since the complete polymerization of N-vinylformamide is usually very time consuming,
Subsequent hydrolysis is carried out in the presence of an additive which removes the acetaldehyde which then forms (for example by oxidizing it to acetic acid or by reducing it to ethanol) or when using an aldehyde scavenger which adds acetaldehyde.
In most cases a monomer conversion of about 99% is sufficient.
Oxidizing agents include all compounds that oxidize acetaldehyde under conditions of hydrolysis. Hydrogen peroxide is preferably used for this. Suitable reducing agents are all compounds which reduce acetaldehyde under hydrolysis conditions. Advantageously, the reducing agent includes sodium borohydride or ascorbic acid.

In order to prevent crosslinking of the hydrolyzed polymer, an aldehyde scavenger is added in the acidic pH range before, during or immediately after the hydrolysis. To this end, the compound
Add, for example, sodium hydrogensulfate, sulfur dioxide, dithionous acid, sodium, hydroxylamine, aminoguanidine, phenylhydrazine, urea and compounds having urea groups, such as ethylene urea and propylene urea. After hydrolysis, the reaction mixture is neutralized. As long as an acid is used for the hydrolysis, a base is used for this purpose, for example sodium hydroxide solution, potassium hydroxide solution, ammonia or a substituted derivative of ammonia. If the hydrolysis is carried out in the presence of a base, the reaction mixture is acidified,
It is preferably neutralized with hydrochloric acid, formic acid or acetic acid.

In order to obtain the finely divided polymer from the suspension, the polymer is first dehydrated by azeotropic distillation, and part of the suspending agent is distilled off,
The finely divided polymer can be filtered off to remove the attached solvent. However, the hydrolyzed polymer can also be isolated directly by filtration or centrifugation. The powdered homopolymer of N-vinylformamide can have a water content of up to 20% by weight without agglomeration on storage. The hydrolyzed polymer does not agglomerate in suspension at substantially higher water contents, but undergoes strong agglomeration or flocculation, for example after removal of the suspending agent at a water content of about 30%. However, a finely divided hydrolyzed polymer of N-vinylformamide having a water content of more than 30% is
It can also be obtained in the form of a free-flowing powder when the hydrolyzed finely divided polymer is treated with finely divided inorganic solids after the hydrolysis is complete. For this purpose, for example, it is possible to charge finely divided inorganic solids into the reaction mixture which is present after hydrolysis and neutralization. Finely divided inorganic solids include, for example, chalk, silicon dioxide (eg Aerosil®), kaolin, titanium dioxide, talc, bentonite, montmorillonite or mixtures of these substances. Advantageously, the finely divided hydrolyzed polymer is contacted with bentonite. 0.1-20, preferably 0.5-10% by weight, based on the polymer, of finely divided inorganic solids are used. After incorporating the finely divided inorganic solids, the hydrolyzed polymer particles are dry and do not stick to each other when stored for a relatively long time. If an inorganic suspension agent is already used in inverse suspension polymerization,
In most cases, the subsequent addition of inert inorganic solids can be dispensed with.

Finely divided inorganic solids can be added to the hydrolyzed polymer after filtration of the suspension and after removal of residual suspending agent from the finely divided polymer.

Hydrolyzed polymer particles left in the highly moist state are surprisingly significantly faster to dissolve in water than anhydrous, hydrolyzed polymer particles of the same composition. High molecular weight hydrolyzed polymers of N-vinylformamide are used in the manufacture of paper as dehydrating, retaining and coagulating agents. In particular, the use of hydrolyzed copolymers, such as particles treated with finely divided inorganic solids, is advantageous. For use in papermaking, the N-vinylformamide units contained in the polymer in each case are from 2 to 60%, preferably from 5 to 4%.
It is hydrolyzed to 0%. Hydrolyzed polymers, such as those which have been treated with finely divided inorganic solids after the end of hydrolysis, are preferred for the production of paper from pulp containing interfering substances.

Next, the present invention will be described in detail with reference to examples. In the following examples,% is% by weight. The K value of the polymer is H.
By Fikentscher, Cellulochemistry, Vol. 13, 48-64 and 71-74 (1932),
Polymer concentration 0.1% by weight in 5% saline solution at temperature 25
Measured at ° C; k = k · 10 ³ .

[0057]

【Example】

Example 1 1000 ml of cyclohexane in a polymerization reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet / outlet and an introduction device.
And 3.8 g of a 34% solution of a copolymer of molecular weight 900 consisting of 90% by weight of dicyclopentadiene, 5% by weight of styrene and 5% by weight of maleic anhydride in cyclohexane.
Is boiled by heating to 60 ° C. in a stream of nitrogen and then applying a vacuum of 600 mbar (absolute). Then, 260 g of N-vinylformamide, distilled water 260
g, 0.13 g of formic acid and 1.3 g of 2,2'-azobis- (2-amidinepropane) -dihydrochloride were prepared, and a pH value of 7. was added using aqueous ammonia.
Adjust to 5. The monomer solution is then freed from atmospheric oxygen by means of a nitrogen stream from the aeration tower and subsequently added within 1 hour at 60 ° C. in the reactor. 5 hours 60
Polymerization at 0 ° C. followed by azeotropic removal of 214 g of water, the precipitating polymer particles having a water content of 15%. The K value of the polymer is 151.

To hydrolyze the poly-N-vinylformamide, 66.8 hydrogen chloride at 60 ° C. in the reaction batch.
g (50 mol calculated on vinylformamide) are introduced and the reaction mixture is heated further at 60 ° C. for 6 hours. A hydrolyzed polymer having a degree of hydrolysis of 28.8% is obtained. After filtering and drying in vacuum, a polymer powder with a water content of 7% is obtained. The average particle size of the polymer particles is in the range of 200 to 1000 μm. The dissolving power of the polymer particles is listed in the table.

Example 2 1000 ml of cyclohexane in a reactor according to Example 1,
A molecular weight of 2000 comprising stearyl alcohol and 1 mol of a copolymer of maleic acid and diisobutene.
1.3 g of 0 monoester are heated to 60 ° C. in a stream of nitrogen and then boiled by applying a vacuum of 600 mbar (absolute). Next, 260 g of N-vinylformamide, 132 g of distilled water, 0.78 g of formic acid and 2,
A solution consisting of 1.3 g of 2'-azobis- (2-amidinepropane) -dihydrochloride is prepared, which is adjusted to a pH of 7.8 with aqueous ammonia. The monomer solution is then purged of atmospheric oxygen with nitrogen and added within 1 hour at 60 ° C. in the reactor. Subsequently, heating is continued for another hour. 103 g of water are driven off by azeotropic distillation. The polymer particles then have a water content of 10%. Polymer K
The value is 180.

After cooling to 60 ° C., 2.5 g of sulfur dioxide and subsequently 20 g of hydrogen chloride (15 mol% calculated on N-vinylformamide) are introduced into the suspension,
The reaction mixture is heated at 60 ° C. for 10 hours. Subsequently, it is cooled and 8.3 g of ammonia are passed into the suspension. Cyclohexane is removed by filtering the polymer particles and drying in vacuum. The resulting hydrolyzed polymer is
It has a degree of hydrolysis of 16.1% and a water content of 5.4%. The particle size of the polymer particles is in the range of 100 to 500 μm. The dissolution rates of this hydrolyzed polymer are listed in the table.

Example 3 In a reactor according to Example 1, 1000 ml of cyclohexane and 2.6 g of montmorillonite modified with dihexadecyldimethylammonium chloride and having a particle size of <2 μm are heated to 60 ° C. in a stream of nitrogen and then 600 mbar (absolute). ) Bring to a boil by applying a vacuum. Then N
260 g of vinylformamide, 123 g of water, 13 g of 10% formic acid and 1.3 g of 2,2'-azobis- (2-amidinepropane) -dihydrochloride are mixed and the pH value of this solution is adjusted by adding aqueous ammonia. .5
Adjust to. Then, atmospheric oxygen is removed from the monomer solution by using nitrogen, and the solution is uniformly added into the reactor within 1 hour, whereupon polymerization is carried out at 60 ° C. under boiling. Subsequently, heating is continued for a further 1 hour and then 47.5 of water is obtained by azeotropic distillation.
drive out g. The polymer particles then have a water content of 25%. The K value of the polymer is 180. After cooling to room temperature,
0.13 g of sodium borohydride is added to the polymer suspension. It is then stirred for 15 minutes. Continuing,
66.8 g of hydrogen chloride (= 50 mol% calculated on polyvinylformamide) are passed into the suspension. The reaction mixture is stirred for 4 hours at 60 ° C. Subsequently, it is cooled and 1.6 g of gaseous ammonia is added. Filtering the polymer particles,
Cyclohexane is removed by drying in vacuum. The polymer obtained has a hydrolysis degree of 48% and a water content of 1
With 3.3%. A good free-flowing polymer has a particle size of 50.
Is about 500 μm.

Example 4 Example 3 is repeated except that 0.35 g of sodium sulfite is used instead of sodium borohydride. The polymer obtained has a hydrolysis degree of 48.8% and a water content of 13%.
Have.

Example 5 In a reactor according to Example 1, 1000 ml of cyclohexane and protective colloid according to US Pat. No. 4,879,361 (Protective Colloid B, ie maleic anhydride for the copolymer of styrene and maleic acid, t-butyl acrylate). And a graft polymer of styrene having a molecular weight of 1870,
1.3 g of the graft copolymer was 32) was heated to 60 ° C. in a stream of nitrogen and then brought to a boil by applying a vacuum of 600 mbar (absolute). Then N
-Vinylformamide 260 g, water 128.3 g, 10
% Formic acid aqueous solution 13 g, sodium diethylenetriaminepentaacetate 0.15 g and 2,2'-azobis- (2-
Amidine propane) -dihydrochloride (1.3 g) was mixed and the pH value was adjusted to 6 by adding 10% aqueous hydrochloric acid.
Adjust to 5. Next, atmospheric oxygen is removed from the monomer solution by introducing nitrogen, and the monomer is uniformly added into the reactor within 1 hour, and polymerization is carried out at 60 ° C. therein. Subsequently, it is further heated at 60 ° C. for 5 hours. The polymer particles have a water content of 35.
%. The K value of the polymer is 180. After cooling to room temperature, 66.8 g of hydrogen chloride (= 50 mol% calculated on polyvinylformamide) are introduced into the suspension. The reaction mixture is then heated for 4 hours at 60 ° C. to hydrolyze. Subsequently, 1.8 g of ammonia is introduced. After the water was driven off by azeotropic distillation, the water content of the polymer particles was 10
Adjusted to%. Cyclohexane is removed by filtering the polymer particles and drying in vacuum. The polymer obtained has a degree of hydrolysis of 50%. Particle size is 50-50
It is 0 μm.

Example 6 A polymer is prepared as in Example 5. After hydrolysis of the polymer, the polymer suspension is halved without driving out the water. After filtering the polymer particles in the first half (a), cyclohexane is removed in vacuo on a rotary evaporator at room temperature.
After that, the polymer particles have a water content of 21% and tend to clump. After standing for 1 day, the polymer particles are completely agglomerated.

The other half (b) of the polymer suspension was filtered and treated with alkaline inactivated bentonite (Opazil).
Cyclohexane is removed at room temperature under vacuum in a rotary evaporator with the addition of 13 g of AF: ®. The polymer particles have a water content of 20.5%. It is itself free-flowing after storage for 4 weeks at room temperature. The polymer particles have a particle diameter of 50 to 700 μm.

Example 7 Poly-N-vinylformamide is prepared as in Example 5. After hydrolyzing with hydrogen chloride to a polymer having a degree of hydrolysis of 15, 26 g of alkaline activated bentonite (Opazil AF: registered trademark) was added to the polymer suspension.
And stir for 1 hour at room temperature. The polymer obtained is subsequently filtered and cyclohexane is removed in vacuo (rotary evaporator). The very free-flowing powder obtained has a water content of 21% and is still in a good free-flowing state after storage for 4 weeks at room temperature. Polymer particles have a diameter of 50-
Having 700 μm.

EXAMPLE 8 700 ml of cyclohexane and 700 g of protective colloid (Protective Colloid B) according to US Pat. No. 4,879,361 were precharged in the reactor according to Example 1 with a K value of 85 under stirring (about 400 rpm). 500 g of a 15% aqueous solution of pyrivinylformamide having The mixture is vigorously stirred for 1 hour. Then, heat and boil. Water is removed by azeotropic distillation until the polymer particles have a water content of 20%. Then the suspension is cooled to room temperature. Thereafter, 19.3 g of gaseous hydrogen chloride (= 50 mol% calculated on polyvinylformamide) are introduced into the suspension and heated to 60 ° C. for 4 hours. Cool it there,
2.4 g of ammonia are introduced into the suspension. The polymer particles are filtered and the cyclohexane is removed by drying under vacuum in a rotary evaporator. The polymer obtained has a degree of hydrolysis of 50% and a water content of 7.7%. The irregularly shaped polymer particles have a particle size of 500 to 2000 μm.

US Pat. No. 4,623,699, Example 1c
Comparative example according to 7.1 g of anhydrous poly-N-vinylformamide-powder is heated to 110 ° C. for 4 hours with anhydrous hydrogen chloride under stirring. The degree of hydrolysis of the polymer is 35% and the K value is 128.

Solubility test of the hydrolyzed polymers obtained according to Examples 1 to 7 and Comparative Example 2 g of each hydrolyzed polymer (calculated to 100%) was distilled water into a 250 ml powder bottle. It is made to be 200 g, and is rotated by a rotating device until the polymer is dissolved. Measure the dissolution process time. Test at 5 minute intervals. The results are listed in the table:

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Valter Dentzinger Federal Republic of Germany Schyupayer Wurmuser Landschuttraße 65 (72) Inventor Michael Clener Mannheim 31 Islebener Wück 8 (72) Inventor Norbert Zenthof Republic Gliün Schuttät Auf der Wuart 16 (72) Inventor Enrique Freudenberger Federal Republic of Germany Schizfell Schuttt Bavarian Schuttrace 4

Claims (5)

[Claims] 1. A powdery polymer containing N-vinylformamide units polymerized and incorporated therein is hydrolyzed in the presence of an acid or a base in an inert suspension agent to give a hydrolyzed powdery polymer. By isolating the coalesced compound of formula: In producing a hydrolyzed powdery polymer of N-vinylformamide having units of 10% by weight, the water content of the hydrolyzed powdery polymer is at least 6 at the beginning of the hydrolysis.
~ 90% by weight, a process for preparing a hydrolyzed powdery polymer of N-vinylformamide. 2. The water content of the polymer is 10 at the beginning of the hydrolysis.
Method according to claim 1, characterized in that it is ˜65% by weight. 3. The method according to claim 1, wherein the hydrolyzed powdery polymer is treated with a finely divided inorganic solid after completion of hydrolysis. 4. Hydrolysis is carried out in the presence of a compound which removes aldehydes from the system.
Or the method according to any one of 2 above. 5. A papermaking dehydration agent, retention agent and coagulant comprising a powdered, hydrolyzed polymer treated with a finely divided inorganic solid obtained according to claim 3.