JP2000239400A - Production of crosslinked polysuccinimide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain crosslinked polysuccinimide reduced in solvent content. SOLUTION: This method for producing polysuccinimide reduced in solvent comprises heating an organic solvent (primary solvent) dissolving at least part of uncrosslinked polysuccinimide and a mixture of primary solvent containing crosslinked polysuccinimide with crosslinked polysuccinimide at 50-300 deg.C to separate crosslinked polysuccinimide reduced in primary solvent from the primary solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a crosslinked polymer, and more specifically, the present invention relates to a method for producing a crosslinked polysuccinimide.

[0002]

2. Description of the Related Art A water-absorbent resin is a resin capable of absorbing water tens to thousands of times its own weight. Sanitary goods such as sanitary products, disposable diapers, breast milk pads, disposable rags, dressing materials for wound protection, and medical care. Medical supplies such as underpads and cataplasms, pet seats, portable toilets, gel air fresheners, gel deodorants, sweat-absorbing fibers, household goods such as disposable warmers,
Toiletries such as shampoos, gels for setting, moisturizers, water retention materials for agriculture and horticulture, life-extending agents for cut flowers, floral foam (fixed material for cut flowers), nurseries for raising seedlings, hydroponics, vegetation sheets, seed tape Agricultural and horticultural products such as fluid seeding, dew condensation prevention agricultural sheets, food tray freshness preserving materials, drip absorbent sheets and other food packaging materials, cooling materials,
Materials for transportation such as water-absorbent sheets for transporting fresh vegetables, building materials for preventing dew condensation, sealing materials for civil engineering and construction, anti-sedimentation agents for shielding methods, concrete admixtures, civil engineering and building materials such as gaskets and packing, optical fibers, etc. Sealing materials for electronic equipment, waterproofing materials for communication cables, electrical equipment related materials such as ink jet recording paper, coagulants for sludge, gasoline, dehydration of oils, water treatment agents such as water removing agents, printing pastes, It is used in a wide range of fields such as water-swellable toys and artificial snow. In addition, using the chemical sustained release, sustained release fertilizer,
Applications for sustained-release pesticides, sustained-release drugs, etc. are also expected. Further, it is expected to be used as a humidity control material utilizing its hydrophilicity, and as an antistatic agent utilizing its charge retention.
However, conventionally, an acrylic acid-based water-absorbing resin is mainly used for the above-mentioned application. Acrylic acid-based water-absorbing resins have little decomposability, and it has been pointed out that they may cause various environmental problems when disposed after use.

[0003] Therefore, biodegradable resins have recently attracted attention as an alternative to conventional non-degradable resins, and it has been proposed to use biodegradable resins as water absorbent resins. As one of them, a resin obtained by crosslinking a polyamino acid has attracted attention. Polyamino acid resins are biodegradable, so they are friendly to the global environment.Even if they are absorbed into the body, they are digested and absorbed by the action of enzymes, and they do not show antigenicity in the body. It is a material that is kind to people because it is clear that there is no material.

As an example of description of such a resin, poly-γ
A method for producing a resin having a high water-absorbing ability by irradiating glutamic acid with γ-rays has been reported (Kunioka et al., Journal of Polymers, Vol. 50, No. 10, p. 755 (1993)). However, from the industrial point of view, ⁶⁰ Co irradiation equipment used in this technique, in order to shut off radioactivity requires large-scale facilities, realistic due to the need for sufficient consideration to the management is not.

[0005] A method of obtaining a hydrogel by crosslinking an acidic amino acid has been reported [Akamatsu, Japan].
No. 52-41309 (U.S. Pat. No. 39488)
No. 63)]. Further, it has been reported that a crosslinked amino acid resin is used as a water-absorbing polymer [Sikes et al.
506244 (International Patent Publication WO92 / 1752)
5)]. However, these resins are not practical because of insufficient water absorption and salt water absorption. JP-A-7-22
No. 4163 discloses a method for producing a water-absorbent resin by mixing a diamine with a polysuccinimide solution, causing a crosslinking reaction, and hydrolyzing the mixture. In Comparative Example 1,
The crosslinked polysuccinimide was converted to isopropyl alcohol (I
Although a method of manufacturing a water-absorbent resin by performing hydrolysis after washing with PA) is disclosed, there is no disclosure regarding washing conditions, specific effects of washing, residual solvent concentration after washing, and the like.

In the case of dissolving an uncrosslinked polymer in a solvent and performing a crosslinking reaction, a subsequent operation (for example, hydrolysis, etc.) is performed without separating the solvent contained in the formed crosslinked polymer. In such cases, there were at least the following problems. Depending on the reaction conditions (for example, reaction temperature, pH, etc.) for performing the subsequent step (for example, hydrolysis step), a side reaction such as a decomposition reaction of the solvent may occur, and the amount of the solvent that can be recovered may decrease.
The water-absorbent resin is denatured and / or decomposed by impurities generated by the decomposition reaction of water, and the water-absorbing performance may be reduced. Excessive energy (for example, due to the separation of impurities generated by the decomposition reaction when regenerating the solvent,
Energy required for distillation).
When the solvent is regenerated, equipment for desalting and removing salts generated by neutralizing the reaction solution after the hydrolysis reaction may be required, and a complicated solvent regeneration step is required.

[0007]

One of the problems to be solved by the present invention is to provide a method for producing a crosslinked polymer having a reduced solvent content.

[0008] One of the problems to be solved by the present invention is:
An object of the present invention is to provide a method for producing a crosslinked polysuccinimide having a reduced solvent content.

[0009]

DISCLOSURE OF THE INVENTION In view of the above problems of the prior art, the present inventors have proposed a method for producing a crosslinked polysuccinimide having a reduced solvent content (hereinafter referred to as a solvent-reduced crosslinked polysuccinimide). As a result of intensive studies, an organic solvent (primary solvent) that dissolves at least a part of the uncrosslinked polysuccinimide and a primary solvent / crosslinked polysuccinimide mixture containing the crosslinked polysuccinimide were mixed with 50% by weight.
The present inventors have found that a solvent-reduced crosslinked polysuccinimide can be produced by heating to about 300 ° C. and separating into a primary solvent-reduced crosslinked polysuccinimide and a primary solvent, thereby completing the present invention.

That is, the present invention is specified by the following items [1] to [11].

[1] A method for producing a solvent-reduced crosslinked polysuccinimide, comprising: an organic solvent (primary solvent) dissolving at least a part of an uncrosslinked polysuccinimide; and a primary solvent comprising the crosslinked polysuccinimide. A method for producing a solvent-reduced crosslinked polysuccinimide, comprising heating a crosslinked polysuccinimide mixture to 50 to 300 ° C. and separating the mixture into a primary solvent-reduced crosslinked polysuccinimide and a primary solvent.

[2] The method of separating the primary solvent-reduced crosslinked polysuccinimide from the primary solvent is at least one selected from the group consisting of extraction, drying, and solid-liquid separation. 1] The method for producing a solvent-reduced crosslinked polysuccinimide according to [1].

[3] The weight of the crosslinked polysuccinimide contained in the primary solvent reduced crosslinked polysuccinimide is represented by W
P, when the weight of the primary solvent contained in the primary solvent-reduced crosslinked polysuccinimide is defined as WA, WP and WA are represented by Formula (1), wherein [1] or [2] A process for producing the described solvent-reduced crosslinked polysuccinimide. 0% by weight ≦ {WA} (WP + WA)} × 100 ≦ 30% by weight (1).

[4] The method for producing a solvent-reduced crosslinked polysuccinimide according to any one of [1] to [3], wherein the primary solvent comprises an aprotic polar solvent.

[5] The aprotic polar solvent is N, N
-The method for producing a solvent-reduced crosslinked polysuccinimide according to [4], which is dimethylformamide (DMF).

[6] In the extraction, an extraction solvent (secondary solvent) that does not substantially dissolve the uncrosslinked polysuccinimide and is compatible with the primary solvent is added to the primary solvent / crosslinked polysuccinimide mixture. The method for producing a solvent-reduced crosslinked polysuccinimide according to any one of [2] to [5], wherein the method reduces the primary solvent into a crosslinked polysuccinimide with reduced primary solvent.

[7] The method for producing a solvent-reduced crosslinked polysuccinimide according to [6], wherein the secondary solvent comprises an organic solvent and / or water.

[8] The organic solvent is at least one selected from the group consisting of alcohols having 1 to 20 carbon atoms, ketones having 3 to 20 carbon atoms, and ethers having 3 to 20 carbon atoms. The method for producing a solvent-reduced crosslinked polysuccinimide according to [7], comprising an organic solvent.

[8] The solvent-reduced crosslinked polysuccinimide according to [8], wherein the organic solvent comprises at least one or more organic solvents selected from the group consisting of methanol, isopropyl alcohol, and acetone. Manufacturing method.

[9] A solvent-reduced crosslinked polysuccinimide obtained by the production method according to any one of [1] to [8].

[10] A method for producing a crosslinked polyaspartic acid-based resin, comprising hydrolyzing an imide ring structure in the solvent-reduced crosslinked polysuccinimide described in [9].

[11] A water-absorbing polymer obtained by the production method described in [10].

[0023]

Embodiments of the present invention will be described below.

[Crosslinked Polyaspartic Resin] As a specific example of the crosslinked polymer of the present invention, a crosslinked polyaspartic resin will be described.

The crosslinked polyaspartic acid-based resin of the present invention is broadly divided into a main chain basic skeleton portion, a side chain portion, and a crosslinked portion in view of its structure. Below, these ~
Will be described.

Structure of Main Chain Basic Skeleton of Crosslinked Polyaspartic Acid-Based Resin The repeating unit of the main chain basic skeleton of the crosslinked polyaspartic acid-based resin produced in the present invention may be composed of an aspartic acid residue alone. Alternatively, a copolymer of aspartic acid and an amino acid other than aspartic acid may be used. In the present invention, the repeating unit composed of aspartic acid in the polymer is referred to as "aspartic acid residue" regardless of the type of bonding.

Specific examples of amino acids other than aspartic acid include, for example, 19 kinds of essential amino acids except aspartic acid, L-ornithine, a series of α-amino acids, and β-amino acids.
Amino acids and amino acids such as alanine, γ-aminobutyric acid, neutral amino acids, acidic amino acids, ω-esters of acidic amino acids, basic amino acids, N-substituted basic amino acids, aspartic acid-L-phenylalanine dimer (aspartame) Derivatives, aminosulfonic acids such as L-cysteic acid and the like can be mentioned. The α-amino acid may be an optically active form (L-form, D-form) or a racemic form.

In the case of a copolymer, any of a block copolymer, a random copolymer and a graft copolymer may be used.

The repeating unit comprising an aspartic acid residue is not particularly limited, but is preferably at least 1 mol%, based on the total number of repeating units constituting the molecule.
mol% or more is more preferable.

The repeating unit of the main chain basic skeleton of the crosslinked polyaspartic acid-based resin is composed of an aspartic acid residue alone or a copolymer with glutamic acid or lysine because of its high water absorbing ability. From the viewpoint of industrial production, it is particularly preferable that the repeating unit consists of an aspartic acid residue alone.

The basic skeleton of the main chain of polyaspartic acid may be such that the amide bond in the main chain is an α bond or a β bond. In the case of polyaspartic acid and its copolymer, an α-bond is formed when the amino group of the aspartic acid or the copolymer unit is bonded to the carboxyl group at the α-position of aspartic acid. When it is bonded to a group, it is a β bond. In the case of this polyaspartic acid, the α bond and the β bond usually exist in a mixed state. In the present invention, the binding mode is not particularly limited.

The side chain group and the crosslinking group of the polymer of the present invention are basically carboxylic acid derivatives in which the carboxyl group of polyaspartic acid is substituted. The details will be described below.

Structure of Side Chain of Crosslinked Polyaspartic Acid Resin The side chain of the crosslinked polyaspartic acid resin has a structure in which the imide ring of the crosslinked polysuccinimide is opened by hydrolysis, and is formed by this hydrolysis. Contains carboxyl groups. Further, the crosslinked polyaspartic acid-based resin may include a side chain having another substituent. Other substituents are not particularly limited, for example, a hydroxyl group, an amino group,
Pendant groups containing at least one mercapto group, carboxyl group, sulfonic acid group, phosphonic acid group, alkyl group, aryl group, aralkyl group and the like can be mentioned. Further, the pendant group may be an alkyl group, aralkyl group, or aryl group having no specific substituent. These pendant groups are preferably those linked to a polyaspartic acid residue by an amide bond, an ester bond, a thioester bond or the like.

The carboxyl group generated by hydrolysis may form a salt even in a free state. Specific examples of the ion forming a salt include, for example, sodium,
Metal ions such as potassium and lithium; ammonium,
Tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, tetrapentylammonium, tetrahexylammonium, ethyltrimethylammonium, trimethylpropylammonium, butyltrimethylammonium, pentyltrimethylammonium, hexyltrimethylammonium, cyclohexyltrimethylammonium, benzyltrimethylammonium , Triethylpropylammonium, triethylbutylammonium, triethylpentylammonium, triethylhexylammonium, cyclohexyltriethylammonium, benzyltriethylammonium and other ammonium ions; trimethylamine, triethylamine, tripropylamine Tributylamine, tripentylamine, trihexylamine, triethanolamine, tripropanolamine, tributanolamine,
Tripentanolamine, trihexanolamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine,
Dicyclohexylamine, dibenzylamine, ethylmethylamine, methylpropylamine, butylmethylamine, methylpentylamine, methylhexylamine, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, octylamine, decylamine, dodecylamine And amine ions such as hexadecylamine.

Of these, the higher the atomic weight or molecular weight of the ion, the higher the molecular weight per monomer unit and the smaller the water absorption per unit weight. Therefore, the smaller the molecular weight of the ion, the better. When there is a possibility of touching human skin or the like, it is preferable that there is no toxicity or that the toxicity is low. From these points, it is preferable to use sodium, potassium, lithium, ammonium and triethanolamine, and it is particularly preferable to use sodium and potassium.

Structure of Crosslinked Portion of Crosslinked Polyaspartic Acid Resin The molecular structure of the crosslinked portion in the crosslinked polyaspartic acid resin is not particularly limited. The crosslinked portion of the crosslinked polyaspartic acid-based resin can be understood as a “bonding portion” with the polymer main chain basic skeleton and a “connecting portion” bridging them.

The "binding portion" of the crosslinked portion of the crosslinked polyaspartic acid resin is not particularly limited. Specific examples thereof include a structure composed of an amide bond, an ester bond, and a thioester bond. These may be used alone or a plurality of structures may be mixed.

On the other hand, the “linking portion” of the crosslinked portion of the crosslinked polyaspartic resin is not particularly limited. The linking moiety may be unsubstituted or substituted with a substituent. Examples of the substituent include an optionally branched alkyl group having 1 to 18 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, an aralkyl group, an optionally substituted phenyl group, and an optionally substituted Good naphthyl group, optionally branched alkoxy group having 1 to 18 carbon atoms, aralkyloxy group, phenylthio group, 1 to 18 carbon atoms
An optionally branched alkylthio group, an optionally branched alkylamino group having 1 to 18 carbon atoms, each alkyl group having an optionally branched dialkylamino group having 1 to 18 carbon atoms, The group has 1 to 1 carbon atoms
8, an optionally branched trialkylammonium group,
Examples include a hydroxyl group, an amino group, a mercapto group, a carboxyl group, a sulfonic acid group, a phosphonic acid group and salts thereof, an alkoxycarbonyl group, an alkylcarbonyloxy group and the like.

For example, alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, cyclopropyl, cyclobutyl, Cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl such as cyclooctyl, benzyl, phenylethyl, phenylpropyl, aralkyl groups such as phenylbutyl, phenyl, tolyl, xylyl,
Chlorophenyl, phenyl group such as biphenyl, naphthyl, naphthyl group such as methylnaphthyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy, heptyloxy, octyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy, Alkoxy groups such as tetradecyloxy, pentadecyloxy, hexadecyloxy, heptyldecyloxy, octyldecyloxy, aralkyloxy groups such as phenoxy, benzyloxy, tolyloxy, methylthio, ethylthio, propylthio, butylthio, pentylthio, hexylthio, heptylthio, Octylthio, nonylthio, decylthio, undecylthio, dodecylthio, tridecylthio, tetradecylthio, pentadecylthio, hexadecylthio Heptyldecylthio, alkylthio groups such as octyldecylthio, phenylthio groups, aralkylthio groups such as benzylthio and tolylthio, methylamino, ethylamino, propylamino, butylamino, pentylamino, hexylamino, heptylamino, octylamino, nonylamino, Decylamino, undecylamino, dodecylamino, tridecylamino,
Alkylamino groups such as tetradecylamino, pentadecylamino, hexadecylamino, heptyldecylamino, octyldecylamino, dimethylamino, diethylamino, dipropylamino, dibutylamino, dipentylamino, dihexylamino, diheptylamino, dioctylamino, Dialkyl such as dinonylamino, didecylamino, diundecylamino, didodecylamino, ditridecylamino, ditetradecylamino, dipentadecylamino, dihexadecylamino, diheptyldecylamino, dioctyldecylamino, ethylmethylamino and methylpropylamino Amino group, trimethylammonium, triethylammonium, tripropylammonium, tributylammonium, tripentylammonium, trihexyl Ammonium, triheptyl ammonium, trioctyl ammonium, trinonyl ammonium, tridecyl ammonium, triundecyl ammonium, tridodecyl ammonium, tritetradecyl ammonium, tripentadecyl ammonium, trihexadecyl ammonium, triheptyl decyl ammonium, trioctyl decyl Ammonium, dimethylethylammonium, dimethylbenzylammonium, trialkylammonium groups such as methyldibenzylammonium, hydroxyl group, amino group, mercapto group, carboxyl group, or sulfonic acid group, or phosphonic acid group, and salts thereof, methyloxycarbonyl , Ethyloxycarbonyl, propyloxycarbonyl, butyloxycarbonyl, pentyloxycarbonyl, Sill oxycarbonyl, heptyloxycarbonyl, octyloxycarbonyl, nonyloxycarbonyl, decyloxycarbonyl, undecyl oxycarbonyl, dodecyloxycarbonyl, tridecyl oxycarbonyl, tetradecyloxy carbonyl, pentadecyloxy carbonyl,
Alkyloxycarbonyl groups such as hexadecyloxycarbonyl, heptadecyloxycarbonyl and octadecyloxycarbonyl, methylcarbonyloxy, ethylcarbonyloxy, propylcarbonyloxy, butylcarbonyloxy, pentylcarbonyloxy, hexylcarbonyloxy, heptylcarbonyloxy, octylcarbonyl Alkyl such as oxy, nonylcarbonyloxy, decylcarbonyloxy, undecylcarbonyloxy, dodecylcarbonyloxy, tridecylcarbonyloxy, tetradecylcarbonyloxy, pentadecylcarbonyloxy, hexadecylcarbonyloxy, heptadecylcarbonyloxy, and octadecylcarbonyloxy Examples thereof include a carbonyloxy group.

When one having a large molecular weight is selected from these, the molecular weight of the crosslinked portion becomes large, the molecular weight per repeating unit becomes relatively large, and the water absorption per unit weight becomes small. It is preferable to select In general, it is also preferable to select a material whose manufacturing process is not complicated. For example, unsubstituted or substituted (for example, methyl, ethyl, methoxy, methyloxycarbonyl and / or methylcarbonyloxy group; and / or hydroxyl group, amino group, mercapto group, carboxyl group, sulfonic acid group and / or Or a phosphonic acid group and / or a salt thereof).

Further, when the crosslinked polyaspartic acid-based resin is used for a water retention material, it is preferable that a polar group is present in the resin molecule. Therefore, the crosslinked portion contains an unsubstituted polar group. Or those substituted by a substituent containing a polar group (for example, a hydroxyl group, an amino group, a mercapto group, a carboxyl group, a sulfonic acid group, a phosphonic acid group and / or a salt thereof).

[Crosslinked Polysuccinimide] The crosslinked polysuccinimide of the present invention preferably has a structure corresponding to the basic skeleton of the crosslinked polyaspartic resin, and / or the basic skeleton of the crosslinked polyaspartic resin. Is a copolymer having a precursor structure corresponding to

[Polysuccinimide] The polysuccinimide used in the present invention may have a linear structure or a branched structure.

The polysuccinimide has a structure corresponding to the main chain basic skeleton of the crosslinked polyaspartic acid-based resin and / or a precursor structure corresponding to the main chain basic skeleton of the crosslinked polyaspartic acid-based resin, May be used.

The method for producing the polysuccinimide used in the present invention is not particularly limited. As a specific example, for example, Neri et al. (Journal of
Medicinal Chemistry, 1973, Vol. 16, No. 8) and the like.

The weight average molecular weight of the polysuccinimide is
Although not particularly limited, generally, the higher the weight average molecular weight, the higher the performance as a water absorbing material and a water retaining material. The weight average molecular weight is generally 30,000 or more, preferably 50,000 or more,
It is more preferably at least 70,000, particularly preferably at least 80,000, most preferably at least 90,000.

[Crosslinking Agent] The crosslinking agent used in the present invention is not particularly limited as long as it is a polyfunctional compound which reacts with at least a part of the uncrosslinked polymer to form a crosslinked structure. For example, when the uncrosslinked polymer is polysuccinimide, a polyfunctional compound that reacts with at least a part of the imide ring portion is used as a crosslinking agent.

For example, polyfunctional compounds such as polyamine and polythiol can be mentioned. Specific examples thereof include hydrazine, ethylenediamine, propylenediamine, 1,4-butanediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine,
Decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tetradecamethylenediamine,
Aliphatic polyamines such as hexadecamethylenediamine, 1-amino-2,2-bis (aminomethyl) butane, tetraaminomethane, diethylenetriamine and triethylenetetramine, norbornenediamine, 1,4-diaminocyclohexane, 1,3,5 One molecule of an alicyclic polyamine such as triaminocyclohexane, isophoronediamine, an aromatic polyamine such as phenylenediamine, tolylenediamine, xylylenediamine, a basic amino acid or an ester thereof, or a monoamino compound such as cystamine or the like; Polyamines such as compounds and derivatives thereof bonded by one or more disulfide bonds, 1,2-ethanedithiol, 1,3-propanedithiol, 1,4-butanedithiol, 1,6-hexanedithiol, pentane Aliphatic polythiols such as rislithiol, alicyclic polythiols such as cyclohexanedithiol, aromatic polythiols such as xylylenedithiol, benzenedithiol, toluenedithiol, trimethylolpropane tris (thioglycolate), trimethylolpropane tris (3-mercaptopro Pionate)
Esters such as pentaerythritol tetrakis (thioglycolate) and pentaerythritol tetrakis (3-mercaptopropionate) polythiol. In addition, protein-constituting amino acids typified by lysine, cystine, and ornithine, and salts or esters thereof are also included.

Among these, ethylenediamine, propylenediamine, 1,4-butanediamine, which have low odor and high reactivity with the imide ring of polysuccinimide
Heptamethylenediamine, hexamethylenediamine, lysine, ornithine and cystamine are preferred.

[Liquid uncrosslinked polysuccinimide] In the present invention, as the liquid polysuccinimide, a solution in which at least a part of the polysuccinimide is dissolved in a solvent, or a dispersion in which the polysuccinimide is dispersed in the solvent, Is preferably prepared. The solvent is a good solvent and / or a poor solvent for polysuccinimide. Specific examples of the good solvent include, for example, N, N-dimethylformamide (DMF), N, N-dimethylacetamide, N-
Aprotic polar solvents such as methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, dimethylsulfoxide, and sulfolane, and the like. Among these, polysuccinimide has high solubility, N,
N-dimethylformamide and N, N-dimethylacetamide are particularly preferred. These solvents may be used alone or in combination of two or more. On the other hand, specific examples of the poor solvent include water, methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, heptanol, octanol, 2-methoxyethanol, alcohols such as 2-ethoxyethanol, ethylene glycol, diethylene glycol, Glycols such as triethylene glycol, propylene glycol and dipropylene glycol, glycosolves such as methyl glycosolve and ethyl glycosolve, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, cyclic ethers such as tetrahydrofuran and dioxane, petroleum ether, Pentane, hexane, heptane, octane, cyclohexane, benzene, toluene,
Ethylbenzene, xylene, decalin, diphenyl ether, anisole, cresol, and the like. Of these, water, methanol, ethanol, propanol, isopropanol, and acetone are particularly preferred because of their relatively low boiling point and ease of solvent recovery. These solvents may be used alone or in combination of two or more.

These poor solvents can also be used for the purpose of adjusting the progress of the crosslinking reaction (for example, slowing the progress of the reaction, etc.).

When preparing a solution in which at least a part of the polysuccinimide is dissolved in a solvent, it is generally preferable to use only the good solvent. When a good solvent and a poor solvent are used in combination, the mixing ratio is not particularly limited, but the uniformity of the crosslinking reaction of the polysuccinimide is not excessively impaired.

As a specific guide, a good solvent and a poor solvent are mixed within a range where the water absorption performance and yield as a crosslinked polyaspartic acid-based resin can be set to desired predetermined values. If the amount of the poor solvent is increased, the effect of the poor solvent is exhibited, the polysuccinimide is in a dispersed state, and the product can be prevented from becoming a gel after the crosslinking reaction.However, since the progress of the crosslinking reaction is usually slow, A large reactor is required. On the other hand, if the poor solvent is reduced or the poor solvent is not used, the effect of the good solvent is exhibited, and a state in which the polysuccinimide has sufficiently uniformity is obtained. In general, if the amount of the poor solvent is reduced, or if the poor solvent is not used, the energy required for solvent recovery can be reduced.

The form of the liquid polysuccinimide is preferably a homogeneous solution. On the other hand, in the case of a dispersed state, it is preferable to make the state as close as possible to a uniform solution. The particle size (average particle diameter) of the polysuccinimide in the dispersed state is preferably as small as possible because a more uniform crosslinking reaction can be performed.
Here, based on the particle size of the polysuccinimide in a dry state, the particle size is preferably,
400 μm or less, more preferably 200 μm or less, further preferably 100 μm or less, particularly preferably 1 μm or less.
0 μm or less. If the polysuccinimide particles are appropriately small, the heterogeneity of the crosslinking reaction can be reduced, and a decrease in yield and a decrease in performance can be prevented.

The particle size of the polysuccinimide can be adjusted by a continuous or batch operation using a dry and / or wet pulverizer. When classification is required, the classification may be performed by a continuous or batch operation using a dry and / or wet classification device. Further, an apparatus having both a pulverizing mechanism and a classification mechanism may be used.

If the particle size of the polysuccinimide is too small to make the operation difficult, a granulation operation using a self-supporting granulation system and / or a forced granulation system may be performed.

As a method for grasping the polysuccinimide particle size (average particle diameter), for example, there is a measuring method using a standard sieve. A standard sieve can be used, for example, with a mechanical shaker, sieved dry or wet to determine the particle size distribution.

As another method for grasping the polysuccinimide particle size (average particle diameter), there is a measuring method by a laser diffraction / scattering method. In this method, the polysuccinimide is usually dispersed in a poor solvent for the polysuccinimide, and the particle size distribution can be measured by a laser diffraction / scattering method.

The concentration of the polysuccinimide in the reaction product containing the polysuccinimide at the time when the crosslinking reaction proceeds is not particularly limited, but is usually preferably 1 to 8
0% by weight, more preferably 5 to 60% by weight, further preferably 10 to 50% by weight, particularly preferably 15 to 50% by weight.
40% by weight. Within these ranges, it is preferable to adjust the concentration in consideration of the mixing property with the liquid crosslinking agent, and to use the polysuccinimide.

[Liquid Crosslinking Agent] In the present invention, in order to obtain a good mixed state with the above liquid uncrosslinked polymer, the crosslinking agent is preferably used as a liquid.

The liquid crosslinking agent in the present invention includes:
A solution in which at least a part of the cross-linking agent is dissolved in a solvent, a dispersion in which the cross-linking agent is dispersed in a solvent, and a melt having a temperature equal to or higher than the melting point of the cross-linking agent are preferably used.

The concentration of the crosslinking agent in the liquid crosslinking agent is not particularly limited, but is usually preferably 0.1 to 100% by weight, more preferably 1 to 90% by weight.
%, More preferably 10 to 85% by weight, particularly preferably 15 to 80% by weight. Within these ranges, it is preferable to adjust the concentration in consideration of the reactivity of the cross-linking agent and the miscibility with the liquid uncross-linked polymer, and use the cross-linking agent. Here, 100% by weight means that a cross-linking agent in a liquid state having a melting point or higher is used without being diluted with a solvent or the like.

In the present invention, an apparatus for producing a liquid crosslinking agent is not particularly limited. For example, as a device for producing a liquid crosslinking agent, a stirring tank, a kneading device, a single-shaft or twin-shaft kneader, or the like can be used.

A solution in which at least a part of a crosslinking agent is dissolved in a solvent A solution in which at least a part of a crosslinking agent is dissolved in a solvent uses a good solvent for the crosslinking agent or a good solvent and a poor solvent for the crosslinking agent. Can be obtained. As used herein, the term "good solvent" includes solvents that can substantially completely dissolve the crosslinking agent. Also, the term "poor solvent" encompasses solvents that cannot substantially completely dissolve the crosslinking agent.

The solvent used is not particularly limited, but may be generally the same as the solvent used for the uncrosslinked polymer (for example, polysuccinimide). In addition, for example, at least one solvent selected from the group of solvents exemplified as the good solvent and the poor solvent for the polysuccinimide may be used. The good solvent and / or poor solvent for the uncrosslinked polymer and the good solvent and / or poor solvent for the crosslinking agent are not necessarily the same.

The solvent used in the present invention is not particularly limited. In general, it is preferable to use only a good solvent. When a good solvent and a poor solvent are used in combination, it is usually preferable that the good solvent and the poor solvent form a homogeneous phase. The mixing ratio is not particularly limited, but the uniformity of the crosslinking reaction of the uncrosslinked polymer is not excessively impaired.

In the present invention, from the viewpoint of uniformity of the crosslinking reaction, it is particularly preferable that the crosslinking agent is a homogeneous solution dissolved in a solvent.

Dispersion in which a cross-linking agent is dispersed in a solvent When a cross-linking agent is used as a dispersion in which a cross-linking agent is dispersed in a solvent, it is preferable to make the state as close as possible to a uniform solution.

The solvent used for preparing the dispersion is a mixed solvent of a good solvent and a poor solvent or a poor solvent for the crosslinking agent.

The particle size (average particle diameter) of the cross-linking agent in the dispersed state is preferably as small as possible because a more uniform cross-linking reaction can be performed. Here, based on the particle size of the crosslinking agent in a dry state, the particle size is preferably 400 μm or less,
More preferably, 200 μm or less, even more preferably,
It is 100 μm or less, particularly preferably 10 μm or less. If the cross-linking agent particles are appropriately small, the non-uniformity of the cross-linking reaction can be reduced, and a decrease in yield and performance can be prevented.

The particle size of the crosslinking agent can be adjusted by a dry method and / or
Alternatively, it can be performed by a continuous or batch operation using a wet pulverizer. When classification is required, the classification may be performed by a continuous or batch operation using a dry and / or wet classification device. Further, an apparatus having both a pulverizing mechanism and a classification mechanism may be used.

When the particle size of the cross-linking agent is too small and the operation becomes difficult, a granulation operation of a self-supporting granulation system and / or a forced granulation system may be performed.

As a method for determining the particle size (average particle diameter) of the cross-linking agent, for example, there is a measuring method using a standard sieve. A standard sieve can be used, for example, with a mechanical shaker, sieved dry or wet to determine the particle size distribution.

The particle size (average particle diameter) of the crosslinking agent
As another method for grasping the condition, there is a measurement method using a laser diffraction / scattering method. In this method, the cross-linking agent is usually dispersed in a poor solvent for the cross-linking agent.
The particle size distribution can be measured by a scattering method.

In the present invention, when the cross-linking agent has a melting point, the melt obtained under the temperature condition not lower than the melting point may be used as the liquid cross-linking agent.

[Amount of Crosslinking Agent] In the present invention, the amount of the crosslinking agent used is not particularly limited. Crosslinked polymers (eg,
The amount of the cross-linking agent to be used is appropriately selected according to the degree of cross-linking at which the performance and properties can be exhibited in accordance with the use of the cross-linked polyaspartic acid-based resin. Here, the degree of cross-linking is defined to indicate the distance between cross-links, the number of constituent monomer units, or the degree of the ratio of cross-linked portions to the polymer main chain.

In general, the amount of the crosslinking agent is preferably 0.001 to 80 mol%, more preferably, 0.001 to 80 mol%, based on the total number of monomer units of an uncrosslinked polymer (for example, polysuccinimide). , 0.01 to 30 mol%, particularly preferably 0.1 to 20 mol%. In general, if the amount of the crosslinking agent is too large, the degree of crosslinking becomes too high, for example,
In the case of a crosslinked polymer that exhibits water absorption, such as a crosslinked polyaspartic acid-based resin, the water absorbing ability is reduced. Conversely, if the amount of the cross-linking agent is too small, the degree of cross-linking becomes too low and eventually becomes water-soluble.For example, in the case of a polyaspartic acid-based resin, it is only partially cross-linked without exhibiting water absorption capacity. Not obtained polymer.

[Catalyst] In the crosslinking reaction, a catalyst may be used if necessary. For example, a base catalyst is generally used as a catalyst in the crosslinking reaction of polysuccinimide.

Examples of the base catalyst include metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, metal carbonates such as sodium carbonate, potassium carbonate and lithium carbonate, sodium hydrogen carbonate and potassium hydrogen carbonate. Metal bicarbonates, metal acetates such as sodium acetate and potassium acetate, metal salts such as sodium oxalate, and inorganic base reagents such as ammonia; trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, trihexyl Amine, triethanolamine, tripropanolamine, tributanolamine, tripentanolamine, trihexanolamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, dicyclohexylamine Ruamine, dibenzylamine, ethylmethylamine, methylpropylamine, butylmethylamine, methylpentylamine, methylhexylamine, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine, octylamine, decylamine, dodecylamine, Organic base reagents such as amines such as hexadecylamine, pyridine, picoline, and quinoline are exemplified.

[Operation for Producing Solvent-Reduced Crosslinked Polysuccinimide] In the present invention, the above-mentioned liquid uncrosslinked polysuccinimide and a liquid crosslinking agent are mixed in the presence of a catalyst or
The solvent is separated from the crosslinked polysuccinimide produced by mixing and crosslinking reaction in the absence of the solvent to produce a solvent-reduced crosslinked polysuccinimide. The operation for producing the solvent-reduced crosslinked polysuccinimide of the present invention is preferably carried out including at least one of the following steps (1) and (2). The number of times each step is performed is not particularly limited. The order in which the steps are performed is not particularly limited. The operation of this step is usually performed by a continuous operation and / or a batch operation.

(1) Step of Increasing Specific Surface Area of Crosslinked Polymer In the present invention, after the crosslinking reaction, a step of increasing the specific surface area of the crosslinked polysuccinimide may be carried out.
The treatment to increase the specific surface area may preferably promote material and heat transfer. The step of increasing the specific surface area (hereinafter, referred to as a specific surface area increasing step) is preferably
Among the functions of subdividing, refining, heating, and decompressing the crosslinked polymer,
This is performed using a device having at least one function.

In the present invention, the cross-linked polymer (cross-linked polysuccinimide) is continuously formed depending on conditions such as the concentration of the uncross-linked polymer (uncross-linked polysuccinimide) and / or the cross-linked polymer, the amount of the cross-linking agent used, and the concentration of the poor solvent. Various forms such as a gel-like body, a swollen body, an udon-like body, and a solid rod-like body can be used.

For example, when a gel-like cross-linked polymer is formed, the shape of the gel-like continuous body to be formed reflects the influence of the shape of the apparatus used for the cross-linking reaction. In addition, the crosslinked polymer can be subdivided to increase the specific surface area. For example, when a tubular reactor is used, the smaller the tube diameter, the larger the specific surface area of the crosslinked polymer, which is preferable. However, usually, the production volume, so that the pressure loss in the tubular reactor does not become excessive,
It is preferable to determine the tube diameter in consideration of various conditions such as the number of tubes of the multitubular reactor.

Further, the finely divided crosslinked polymer can be converted into a granular to fine granular gel by using a device having a function of mechanically reducing the size of the particles, such as a cutting device or a pelletizer device. Further, a crushing granulation device, a compression granulation device, an extrusion granulation device, or the like can also be used. When the crosslinked polymer is refined, specifically, the maximum particle diameter is preferably 1 μm to 10 mm, more preferably 10 μm to
It is adjusted to be 1 mm, particularly preferably 100 to 700 μm. Using an apparatus having a function of mechanically finely graining, depending on the application, selected from the above range,
A crosslinked polymer having a preferred maximum particle diameter is prepared. Here, the maximum particle diameter can be evaluated by the same method as that for the above-mentioned uncrosslinked polymer.

When the crosslinked polymer is swollen by a crosslinking solvent (a solvent used for preparing a liquid uncrosslinked polymer and / or a liquid crosslinking agent), it is a poor solvent for the crosslinked polymer. By introducing a cross-linked polymer into a solvent, which is a good solvent for the cross-linking solvent, the cross-linked polymer can be contracted and made finer. At this time, by performing stirring or the like and applying a shearing force, it is also possible to promote finer particles of the crosslinked polymer. In the case of performing fine-graining in a solvent, heat treatment may be used in combination. If the temperature for the heat treatment is too low, it takes a long time until the crosslinked polymer is refined, and a large-sized apparatus may be required. Conversely, if the temperature for the heat treatment is too high, the crosslinked polymer may be denatured. In particular, the temperature at the time of performing the heat treatment together with the grain refinement is preferably from 30 to 3
The temperature is set to 00 ° C, more preferably 60 to 200 ° C, and still more preferably 80 to 150 ° C.

For example, when the crosslinked polysuccinimide is a gel-like substance swollen with N, N-dimethylformamide (DMF) as a crosslinking solvent, methanol is a poor solvent for crosslinked polysuccinimide and a good solvent for DMF. Into a solvent such as alcohols, ketones such as acetone, and water, and heat treatment is performed in the above-mentioned temperature range to give a shearing force, whereby fine particles can be formed.

When a cross-linking solvent is used, the solvent contained in the cross-linked polymer is evaporated by performing a heat treatment and / or a reduced pressure treatment. The foaming state can efficiently increase the specific surface area of the crosslinked polymer.

The heat treatment is preferably performed at 30 to 300
C., more preferably at 60 to 200C, even more preferably at 80 to 150C. If the temperature for the heat treatment is too high, the crosslinked polymer may be denatured. Conversely, if the temperature at which the heat treatment is performed is too low, the effect of the heat treatment may not be obtained.

Further, the decompression treatment is preferably performed at 0.00
001 to 0.1 MPa, more preferably 0.0001
To 0.07 MPa, more preferably 0.001 to
It is performed at 0.05 MPa. If the pressure at which the decompression process is performed is too low, it is usually difficult to design an apparatus that can handle a high vacuum. Conversely, if the pressure at which the decompression treatment is performed is too high, the effect of the decompression treatment may not be obtained.

The crosslinked polymer whose specific surface area has been increased by the above-mentioned method, for example, in the case of crosslinked polysuccinimide, can also have the effect of shortening the hydrolysis reaction time in the hydrolysis step described below. .

The apparatus used in the specific surface area increasing step of the present invention is not particularly limited. The equipment used in the process of increasing the specific surface area is described in “Revision 6
Handbook of Chemical Engineering ”(editor: Japan Society for Chemical Engineering, Published by Maruzen Co., Ltd., 1999),“ 7 Stirring ”(42)
1-454), “6 Heat transfer and evaporation” (343-420)
Page 5), "5 Fluids" (pages 283 to 342), and "16 Granulation" (pages 835 to 894).

(2) Step of Isolating Crosslinked Polymer In the present invention, the crosslinking polymer (crosslinked polysuccinimide) is isolated by separating the crosslinking solvent (primary solvent) after the crosslinking reaction, and the solvent-reduced crosslinked polysuccinimide is obtained. To manufacture.
In the present invention, after the crosslinking reaction, the crosslinking solvent (primary solvent)
And a salt (eg, sodium chloride, sodium phosphate, etc.) to isolate the crosslinked polymer to produce a solvent-reduced crosslinked polysuccinimide. However, salts are not necessarily limited to those separated with the crosslinking solvent.

In the present invention, the concentration of the crosslinking solvent in the crosslinked polymer is preferably 50% by weight or less, more preferably 30% by weight.
% By weight or less, more preferably 10% by weight or less, particularly preferably 5% by weight or less, most preferably 1% by weight or less,
It is preferable to isolate the crosslinked polymer by separating the crosslinked solvent so that If the residual solvent concentration in the crosslinked polymer is too high, the crosslinked polymer may have adhesive properties and require special equipment (for example, equipment related to transfer, storage, etc.).

The step of isolating the crosslinked polymer in the present invention preferably comprises the following (2-1) extraction step, (2-
It comprises at least one step selected from 2) a solid-liquid separation step and (2-3) a drying step.

When performing a plurality of steps among (2-1) to (2-3), the order is not limited. Further, each step may be repeated a plurality of times. Also,
It may be carried out in combination with the above specific surface area increasing step.

Further, the process of the present invention can be carried out continuously,
Alternatively, it can be carried out batchwise.

(2-1) Extraction Step The extraction operation of the present invention is preferably performed using a solvent that is a poor solvent for the crosslinked polymer and a good solvent for the crosslinked solvent. For example, when the crosslinked polymer is a crosslinked polysuccinimide manufactured using DMF, one or more solvents (for example, water,
It is particularly preferred to select methanol, ethanol, propanol, isopropanol, acetone, etc.).
These solvents may be used alone or in combination of two or more. The solvent may contain salts (for example, sodium chloride, sodium phosphate, etc.).

Examples of the apparatus used in the extraction operation include:
A stirring tank, a fixed bed extractor, a moving bed extractor, a rotocell extractor, and the like can be used. Examples of the apparatus and method used for the extraction operation of the present invention include “12 Extraction / Liquid Liquid” in “Revised Sixth Edition Chemical Engineering Handbook” (editor: The Society of Chemical Engineers, Published by Maruzen Co., Ltd., 1999). Reaction ”(63
7-688), “7 Stirring” (pages 421-454),
The apparatus and the method described in “6 Heat Transfer / Evaporation” (pages 343 to 420) are included.

The extraction operation is performed by one-stage or multi-stage extraction. In the multi-stage extraction, the extraction solvent is used in a countercurrent type or a cocurrent type, but the countercurrent type is particularly preferable in that the amount of the extraction solvent used is suppressed. In the multi-stage extraction operation, an extraction solvent containing a cross-linking solvent may be used in at least some of the stages.

The amount of the extraction solvent used determines the residual concentration of the cross-linking solvent and the salts after the extraction operation. The amount of the extraction solvent used is usually preferably from 0.1 to 100 parts by weight, more preferably from 0.3 to 60 parts by weight, particularly preferably from 0.5 to 40 parts by weight, most preferably from 0.5 to 40 parts by weight, based on the weight of the crosslinked polymer. Is 1 to 20 parts by weight. If an excessive amount of the extraction solvent is used, the residual concentration of the cross-linking solvent in the extract becomes low, so that the efficiency of separating the cross-linking solvent and the extraction solvent after extraction deteriorates. On the other hand, if the amount of the extraction solvent is too small, the concentration of the cross-linking solvent in the extract will increase, and the concentration of the cross-linking solvent remaining in the cross-linked polymer will increase. In order to reduce the amount of the extraction solvent used and to perform the extraction operation efficiently, a multi-stage countercurrent type extraction operation is preferable.

In the case of performing multi-stage extraction, it is preferable to perform the operation in the next stage after separating the crosslinked polymer and the extract as much as possible between the stages. In particular,
The extract contained per 100 parts by weight of the crosslinked polymer is generally 100 parts by weight or less, preferably 50 parts by weight or less, more preferably 20 parts by weight or less, particularly preferably 10 parts by weight or less, and most preferably 5 parts by weight or less. Separate until it is less than parts by weight.

The separation of the extract from the crosslinked polymer can be carried out by a filter, a centrifuge, a sedimentation device, a flotation device, or a combination thereof. In addition, after separating the crosslinked polymer and the extract, further using the same type or a different type of extraction solvent,
The replacement washing of the extract contained in the crosslinked polymer may be performed. The amount of the extraction solvent used per one displacement washing operation is preferably 0.01 to 50 parts by weight per 1 part by weight of the crosslinked polymer.
Parts by weight, more preferably 0.05 to 10 parts by weight, particularly preferably 0.1 to 5 parts by weight.

In the present invention, the temperature of the extraction operation is 5-30.
0 ° C. is preferred. When this temperature is lower than 5 ° C., the concentration of the crosslinked solvent remaining in the crosslinked polymer increases. On the other hand, when the temperature exceeds 300 ° C., a part of the crosslinked polymer is denatured, the molecular weight is reduced, and in some cases, the polymer is colored, and the quality of the polymer is reduced. This temperature is preferably from 10 to 200 ° C., and from 15 to 1
50 ° C is more preferable, and 20 to 100 ° C is particularly preferable.

The pressure in this step is determined by the properties of the extraction solvent used. When the temperature at which the extraction operation is performed is lower than the critical temperature of the extraction solvent, the pressure is set so that the liquid phase exists at least partially. For example, in the case where extraction is performed in an atmosphere of an inert gas such as nitrogen, carbon dioxide, argon, or the like, the pressure of the gas may be higher than the saturated vapor pressure of the extraction solvent at the extraction temperature. When the temperature at which the extraction operation is performed is higher than the critical temperature of the extraction solvent, the pressure is such that at least a part of the crosslinking solvent is dissolved in the extraction solvent.

In the case of performing multi-stage extraction, the temperature and / or pressure in each stage may be set to different values within the above range.

The time required for the extraction operation of the present invention is generally 0.5 seconds to 12 hours, preferably 1 second to 5 hours, more preferably 3 seconds to 3 hours, and particularly preferably 5 seconds to 2 hours. , Most preferably from 10 seconds to 60 minutes. Here, the extraction time is the time during which the polymer is in contact with the extraction solvent and / or the extract at the temperature at which the extraction is performed. If a long time is required for extraction, a large-sized device is required, and it is difficult to design the device. On the other hand, if the extraction time is too short, the separation of the cross-linking solvent and the salts in this step may not be sufficiently performed.

(2-2) Solid-Liquid Separation Step As the separation operation in the solid-liquid separation step of the present invention, the same method as the separation operation performed between each stage of the multistage extraction described above can be mentioned. That is, specifically, the separation operation can be performed by a filter, a centrifugal separator, a sedimentation separator, a flotation separator, or a process combining them.

(2-3) Drying Step In the drying step, a crosslinking solvent contained in the crosslinked polymer,
And / or by drying the extraction solvent, a crosslinked polymer substantially containing no solvent can be produced.

The drying operation can be performed under at least one pressure condition among a vacuum system, a normal pressure system, and a pressure system.

Specifically, for example, a hot air transfer type dryer,
At least one device selected from the group consisting of a material stirring type dryer (fluidized bed dryer, etc.), a material transport and stationary type dryer, a cylindrical dryer, an infrared dryer, a microwave dryer, and a superheated steam dryer. , A continuous or batchwise drying operation can be performed.

The apparatus and method used in the drying step of the present invention are described in “Revised Sixth Edition Chemical Engineering Handbook” (editor: Japan Society for Chemical Engineering, publishing office: Maruzen Co., Ltd., 1
999) "14 Humidity control, water cooling and drying" (735-735)
788), "7 Stirring" (pages 421-454), "6
Heat transfer / evaporation ”(pages 343 to 420).

In order to prevent the crosslinked polymer from being colored or denatured, the drying operation is usually preferably carried out under a condition where the oxygen concentration in the system is reduced or under a condition where the oxygen concentration is 0%. It is preferable to carry out in the above-mentioned inert gas.

The drying operation is preferably performed so that the temperature of the crosslinked polymer during the drying operation is 5 to 300 ° C. If the temperature is lower than 5 ° C., it usually takes a long time to dry the crosslinked polymer. On the other hand, when the temperature exceeds 300 ° C., usually, a cross-linking solvent and / or an extraction solvent is contained, so that a part of the cross-linked polymer is denatured, the molecular weight is reduced, and in some cases, the polymer is colored, May cause a decrease. This temperature is preferably 20 to 200 ° C, more preferably 40 to 150 ° C, and 50 to 120 ° C.
C is particularly preferred.

The drying operation may be any of a vacuum system, a normal pressure system, and a pressure system. The pressure of the drying operation is preferably between 0.
00000 to 5 MPa, more preferably 0.000
It is carried out at 01 to 1 MPa. If the pressure is too low, it is usually difficult to design a device compatible with high vacuum.
Conversely, if the pressure is too high, the cross-linking solvent may not usually be sufficiently separated.

The time required for the drying operation of the present invention is generally 1 second to 20 hours, preferably 30 seconds to 5 hours, more preferably 1 minute to 3 hours, and particularly preferably 5 minutes to 2 hours. is there. When a long time is required for drying, a large-sized apparatus is usually required, and it is difficult to design the apparatus. On the other hand, if the drying time is too short, the separation of the cross-linking solvent in this step usually may not be sufficiently performed.

[Hydrolysis of imide ring of cross-linked polysuccinimide] In the present invention, the cross-linked polysuccinimide is
A hydrolysis operation may be performed. By this operation, the imide ring structure can be opened to obtain an aspartic acid structure. As described above, the crosslinked polysuccinimide is in a state where the solvent is completely separated (solvent concentration: 0% by weight).
However, the solvent may be contained in the above concentration range.

The hydrolysis operation is carried out under a basic condition by suspending the crosslinked polysuccinimide in a solvent. The pH is adjusted by the concentration of the alkaline aqueous solution.
The pH is 5 to 13, more preferably 9 to 12. If the pH is too high, the amide bond is usually hydrolyzed, and the resulting resin has poor water absorption performance and yield. Conversely, if the pH is too low, the hydrolysis reaction usually slows down and is not practical.

The alkaline aqueous solution used in the hydrolysis operation is not particularly limited. Specifically, for example, metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, metal carbonates such as sodium carbonate, potassium carbonate and lithium carbonate, and metal carbonates such as sodium hydrogen carbonate and potassium hydrogen carbonate Examples thereof include hydrogen salts, metal acetates such as sodium acetate and potassium acetate, metal salts such as sodium oxalate, and aqueous ammonia. Of these, inexpensive sodium hydroxide and potassium hydroxide are preferred.

The temperature at which the hydrolysis operation is performed is preferably 5
-100 ° C, particularly preferably 10-60 ° C. If the temperature is too high, hydrolysis of the amide bond usually occurs, and the water absorption performance and yield of the resulting resin are reduced. Conversely, if the temperature is too low, the hydrolysis reaction usually slows down and is not practical.

The hydrolysis operation may be performed at normal pressure or reduced pressure as long as the pressure is such that at least a part of the liquid phase exists. It is sufficient that a stable hydrolysis operation can be performed. The pressure is usually preferably 30 MPa or less, and 5MPa.
It is particularly preferable that the ratio is not more than a. The time for performing the hydrolysis operation varies depending on the reaction conditions, but is generally preferably 1 minute to 30 hours, more preferably 5 minutes to 15 hours, still more preferably 10 minutes to 10 hours, and particularly preferably 30 minutes to 30 hours. Minutes to 5 hours. If the reaction time is too short,
Usually, since the hydrolysis of the imide ring is not sufficient, the water absorption performance is reduced. Conversely, if the reaction time is too long, the hydrolysis of the amide bond portion usually proceeds, and the water absorption performance and yield of the resulting resin decrease.

The solvent in the hydrolysis operation is water alone or a mixed solvent of water and a poor solvent and / or salts. The amount of the solvent used is preferably 0.5 to 50 times by weight, particularly preferably 1 to 10 times by weight of the water-absorbing resin to be produced, in order to increase the volumetric efficiency.

Although the poor solvent to be used is not particularly limited,
For example, methanol, ethanol, propanol, isopropanol, butanol, 2-methoxyethanol,
Alcohols such as 2-ethoxyethanol; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and dipropylene glycol; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; cyclic ethers such as tetrahydrofuran and dioxane; , N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, dimethylsulfoxide, sulfolane and the like. Among them, methanol, ethanol, propanol, isopropanol, and acetone are preferred because they are particularly easy to dry when they are dried as a water-absorbent resin, and the solvent hardly remains in the composition after drying.

The salts used are not particularly restricted but include, for example, metal salts or organic base salts such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, carbonic acid, organic sulfonic acids and organic carboxylic acids, and oxides. Can be Examples of the metal of the metal salt include lithium, sodium, potassium, aluminum, calcium and the like. The salts may be those generated by neutralizing acidic components in the system in the course of the hydrolysis operation.

The water concentration when evaluated with only two components, water and poor solvent, without considering salts in the solvent is preferably 5%.
-100% by weight, more preferably 20-80% by weight,
More preferably, the content is 40 to 60% by weight. When the water concentration is too low, the progress of the hydrolysis is usually slow,
In some cases, aggregation of the polymer may occur in the system, making stirring difficult. Conversely, if the water concentration is too high, the inside of the system usually becomes gel-like, which makes stirring difficult.

The salt concentration in water and salts or in a solvent composed of water, a poor solvent and salts is preferably 20% by weight or less, more preferably 10% by weight or less. Usually, when the concentration of the salt is too low, the effect is small, and when the concentration is too high, the salt may remain in the product.

[Post-Treatment of Cross-Linked Polyaspartic Resin] The post-treatment of the cross-linked polyaspartic resin produced by subjecting the imide ring of the cross-linked polysuccinimide to an alkaline hydrolysis reaction is not particularly limited. For example,
Neutralization treatment, salt exchange treatment, drying, purification, granulation, pulverization, classification, surface cross-linking treatment and the like may be performed as necessary. Hereinafter, the neutralization treatment and the drying are particularly described.

Neutralization Treatment of Cross-Linked Polyaspartic Acid-Based Resin The neutralization treatment of cross-linked polyaspartic acid-based resin may be performed as necessary. In the neutralization treatment, the reaction solution containing the crosslinked polyaspartic acid-based resin after the hydrolysis reaction has a desired pH.
(For example, pH 7) by adding an acid or a base. By this neutralization treatment, the proportion of carboxyl groups present in the molecules of the crosslinked polyaspartic acid-based resin as salts (neutralization degree) can be adjusted.
Although the degree of neutralization is not particularly limited, generally, the ratio of the carboxyl group forming a salt is usually 0 based on the total number of all aspartic acid residues in the molecule of the crosslinked polyaspartic acid-based resin. ~ 95 mol% is preferable, and 30 ~
80 mol% is more preferable.

The method of neutralization is not particularly limited, but after the hydrolysis reaction, an acid and / or a base is added to adjust the pH.
Is generally adjusted. Specific examples of the acid used include hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, sulfurous acid, nitric acid, nitrous acid, carbonic acid, phosphoric acid, formic acid, acetic acid, propionic acid, oxalic acid, benzoic acid, methanesulfone Acids, trifluoromethanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, benzenephosphonic acid and the like.
Further, specific examples of the base to be used include the above-mentioned alkaline aqueous solution.

Drying of Crosslinked Polyaspartic Acid Resin The method of drying the water absorbent resin is not particularly limited. Drying is performed in a batch or continuous operation under normal pressure or reduced pressure. Specifically, at least one selected from the group consisting of a stationary material dryer, a material transport dryer, a material stirring dryer, a hot air transport dryer, a cylindrical dryer, an infrared dryer, and a high frequency dryer. The drying operation is performed using three devices.
The apparatus and method used in the drying operation of the present invention are described in “Revised Sixth Edition Chemical Engineering Handbook” (editor: Japan Incorporated Association)
The Society of Chemical Engineers, Published by Maruzen Co., Ltd., 1999) "14 Humidity Control, Water Cooling, Drying" (pp. 735-788),
The apparatus and method described in “7 Stirring” (pages 421 to 454) and “6 Heat transfer / evaporation” (pages 343 to 420) are included. In general, the temperature of the crosslinked polyaspartic acid-based resin in the drying operation is preferably from 20 to 200C, more preferably from 50 to 120C. If the temperature is too high, the degree of crosslinking usually decreases, and the water absorption performance decreases.
Conversely, if the temperature is too low, drying takes a long time and requires a large-sized apparatus.

The amount of the solvent (including water) contained in the water-absorbent resin after the drying operation is appropriately adjusted depending on the use. Per 100 parts by weight of the water absorbent resin, preferably 50 parts by weight or less, more preferably 20 parts by weight or less, further preferably 10 parts by weight or less, particularly preferably 7 parts by weight or less, most preferably 5 parts by weight. The following is assumed.

The dried water-absorbent resin may be further subjected to a granulation treatment, a surface cross-linking treatment, and the like, if necessary.

[Shape of crosslinked polyaspartic resin]
The shape of the water-absorbent resin depends on the application, such as irregularly crushed, spherical, granular, granular, granulated, scaly, massive, pearl, fine powder, fibrous, rod, film, sheet, etc. Preferred shapes can be selected and used. Further, it may be a fibrous base material, a porous material, a foam, or a granulated material.

The particle size (average particle diameter) of these water-absorbing resins is not particularly limited, but is preferably adjusted depending on the use.

For example, in the case of disposable diapers, since it is desired that a high water absorption rate and no gel blocking occur, the average particle diameter is usually preferably 50 to 1000 μm.
100-600 μm is more preferred. In addition, waterproof material,
When used for mixing with other resins, it is usually 1 to 1
0 μm is preferable, and when used as a water retention material for agriculture and horticulture, usually 100 μm to
5 mm is preferred.

In the present invention, the operation to be performed to obtain the above shape is not particularly limited. In the present invention, at least one operation selected from the group consisting of pulverization, classification, and granulation is preferably performed. These operations can be performed continuously and / or batchwise.

[Form of Use of Crosslinked Polyaspartic Acid Resin] The form of use of crosslinked polyaspartic acid resin is as follows.
It is not particularly limited, and may be used alone or in combination with other materials.

For example, when used in combination with another resin,
A method of kneading with a thermoplastic resin and molding by injection molding or the like, a method of mixing a monomer of the constituent resin with an acidic polyamino acid-based resin and, if necessary, an initiator, and polymerizing with light or heat, etc., and a resin and a crosslinked polyasparagine. Dispersing the acid-based resin in a solvent, casting, removing the solvent, mixing the prepolymer and the cross-linked polyaspartic resin, then cross-linking, mixing the resin and the cross-linked polyaspartic resin,
There is a method of crosslinking and the like.

The molded product of the crosslinked polyaspartic resin is not particularly limited, and can be used as a solid, a sheet, a film, a fiber, a nonwoven fabric, a foam, a rubber and the like. Also, the molding method is not particularly limited.

On the other hand, the crosslinked polyaspartic acid resin is
It may be used alone or in a composite with other materials. The structure of the complex is not particularly limited, for example,
There are a method of sandwiching a pulp layer, a nonwoven fabric, or the like to form a sandwich structure, a method of forming a multilayer structure using a resin sheet or a film as a support, and a method of casting a resin sheet to form a two-layer structure. For example, if a crosslinked polyaspartic acid-based resin is formed into a sheet, a water-absorbing sheet (including a water-absorbing film) can be obtained.

Further, the crosslinked polyaspartic resin is
If necessary, it may be used by mixing with one or more other water-absorbing resins. If necessary, an inorganic compound such as salt, colloidal silica, white carbon, ultrafine silica, titanium oxide powder, or an organic compound such as a chelating agent may be added. In addition, oxidizing agents, antioxidants, reducing agents,
An ultraviolet absorber, an antibacterial agent, a bactericide, a fungicide, a fertilizer, a fragrance, a deodorant, a pigment, and the like may be mixed.

The crosslinked polyaspartic acid resin can be used as a gel or as a solid. For example, when used as a water retention material for agricultural and horticultural use, a cut flower life-promoting agent, a gel fragrance, a gel deodorant, etc., it is used as a gel, and a paper diaper absorber is used as a solid.

[Uses of Crosslinked Polyaspartic Acid Resin]
Although the use of the crosslinked polyaspartic acid-based resin is not particularly limited, it can be used in any of the applications where a conventional water-absorbing resin can be used.

For example, sanitary articles such as sanitary articles, disposable diapers, breast milk pads, disposable rags, dressing materials for wound protection, medical articles such as medical underpads, cataplasms,
Pet seats, portable toilets, gel air fresheners, gel deodorants, sweat-absorbing fibers, household items such as disposable warmers, toiletries such as shampoos, set gels, moisturizers, water retention materials for agriculture and horticulture, Agricultural and horticultural supplies, food trays, etc., for life extension of cut flowers, floral foam (fixed material for cut flowers), nursery beds, hydroponic vegetation sheets, seed tapes, fluid seeding media, dew condensation prevention agricultural sheets, etc. Food packaging materials such as freshness preservation materials, drip absorbent sheets, cold insulation materials,
Transportation materials such as water-absorbent sheets for transporting fresh vegetables, building materials for preventing dew condensation, sealing materials for civil engineering and construction, anti-sedimentation agents for shielding methods, concrete admixtures, civil engineering construction materials such as gaskets and packing, and electronic equipment , Sealing materials such as optical fibers, waterproof materials for communication cables, materials related to electrical equipment such as ink jet recording paper, coagulants for sludge, water treatment agents such as gasoline and oil dehydration, water removal agents, etc., printing pastes, Water-swellable toys, artificial snow, sustained-release fertilizers, sustained-release pesticides,
Sustained-release drugs, humidity control materials, antistatic agents, and the like.

[0144]

The present invention will be described below in detail with reference to examples. However, the present invention is not limited to the following examples.

[Evaluation of Solvent Concentration in Cross-Linked Polymer] In the examples, the weight concentration of N, N-dimethylformamide (DMF) in the cross-linked polymer was determined by using a pyrolysis GC apparatus including the following apparatus. Was evaluated. The analysis was conducted by rapidly raising the temperature of the crosslinked polymer to 300 ° C. in the following pyrolyzer to volatilize the contained solvent, separating and quantifying DMF using a GC connected to the pyrolyzer. It was done. The DMF concentration in the crosslinked polymer is a value based on the weight of the crosslinked polymer including the solvent.

Pyrolyzer: PYR-2A (Shimadzu) GC column: Chromosorb 103 (Shimadzu).

[Evaluation of Water Absorption] The water absorption in the examples was measured by the following tea bag method. The measurement of the water absorption by the tea bag method was performed on physiological saline and distilled water.

Dried water-absorbing resin (particle size: 100 to 50)
0.02 g of a dry-classified product having 0 μm) is placed in a non-woven tea bag (80 mm × 50 mm) and immersed in an excess of a corresponding solution (saline or distilled water) to swell the resin for 40 minutes. After that, pull up the tea bag and take 1
After draining for 0 second and further draining on 24 sheets of tissue paper for 10 seconds, the weight of the tea bag containing the swollen resin was measured. From the weight, the value obtained by subtracting the value obtained by subtracting the weight of the water-absorbent resin when dried from the blank weight and the weight of the water-absorbent resin when the same operation was performed only with the tea bag by the weight of the water-absorbent resin, Was evaluated for water absorption weight per unit weight (g / g-water-absorbing resin). The physiological saline is a 0.9% by weight aqueous sodium chloride solution.

Example 1 A flask equipped with a stirrer was charged with 80 g of DMF and 20 g (0.21 mol) of polysuccinimide (weight average molecular weight 136,000), and a uniform polymer solution was added. Obtained.

Under a nitrogen stream, 15 g of a crosslinking agent solution [5.3 g of L-lysine monohydrochloride was added to a mixed solution consisting of 1.4 g (0.035 mol) of sodium hydroxide and 8 g of distilled water.
(0.029 mol) and neutralized hydrochloric acid]
It was introduced at 25 ° C. over 30 seconds. Five minutes after the addition of the crosslinking agent solution, the reaction mass became a gel characteristic of the crosslinked product, and the stirring was stopped. The crosslinked product was allowed to stand at 25 ° C. for 24 hours.

Next, 80 g of distilled water and 100 g of methanol
g of the mixed solution was charged into a pulverizer, and the crosslinked product was wet-pulverized with stirring, followed by filtration to recover the pulverized crosslinked polymer. The collected crosslinked polymer was dried under vacuum to obtain 28.5 g of powdery crosslinked polymer A (DMF concentration:
14% by weight).

Next, 6 g of the crosslinked polymer A was charged into a tubular extractor, and 4 g of methanol was added using a high-pressure pump.
g / min, and a fixed-bed extraction operation was performed at 90 ° C. and 1 MPa for 1 hour. After the extraction, the crosslinked polymer B was recovered from the tubular extractor. Vacuum drying was performed to obtain 5.1 g of a crosslinked polymer B. The DMF concentration of the crosslinked polymer B was 0.7% by weight.

Further, 4 g of the crosslinked polymer B was
Aqueous sodium hydroxide solution (sodium hydroxide concentration: 25% by weight) was added at 25 to 30 ° C. so as to maintain the pH at 11.5 to 12, and the mixture was hydrolyzed at 25 to 30 ° C. As a result, a viscous gel was obtained. After hydrolysis, the mixture was neutralized to pH 7 with a 7% hydrochloric acid solution, and the gel was introduced into a large excess of methanol and solidified. Next, the solid was recovered by filtration, washed, and dried to obtain 4.5 g of a crosslinked polyaspartate.

The water absorption of the obtained polymer with respect to distilled water was 990 [g / g-polymer] (after 40 minutes),
The water absorption with respect to physiological saline was 76 [g / g-polymer] (after 40 minutes).

Example 2 6 g of the crosslinked polymer A obtained in Example 1 was charged into an eggplant-shaped flask, and the pressure was 1 mmH
g (0.00013 MPa) to 150 ° C.
DMF was separated for 2 hours. The amount of the recovered crosslinked polymer B was 5.3 g (DMF concentration: 2.5% by weight).

Further, the same operation as in Example 1 was repeated for 4 g of the crosslinked polymer to obtain 4.6 g of a water absorbent resin. The water absorption of the obtained polymer with respect to distilled water was 470 [g / g-polymer] (after 40 minutes), and the water absorption with respect to physiological saline was 51 [g / g-polymer] (after 40 minutes). there were.

Example 3 A flask equipped with a stirrer was charged with 12 g of DMF and 3 g of polysuccinimide (weight average molecular weight 100,000) to obtain a uniform polymer solution. Under a nitrogen stream, 0.41 g of a crosslinking agent solution [DMF
0.35 g of a homogeneous solution obtained by dissolving 0.061 g of hexanediamine] at 25 ° C. over 30 seconds.
Four minutes after the addition of the cross-linking agent solution, the reaction mass became a gel specific to the cross-linked product, and the stirring was stopped. The crosslinked product was allowed to stand at 25 ° C. for 10 hours.

Next, the crosslinked product was charged into an eggplant flask,
At 150 ° C. and 5 mmHg (0.00067 MPa),
DMF was separated for 1 hour. The recovered crosslinked polymer was 3.2 g (DMF concentration: 5% by weight).

Further, the same operation as in Example 1 was repeated for 4 g of the crosslinked polymer to obtain 3.7 g of a water absorbent resin. The water absorption of the obtained polymer with respect to distilled water was 410 [g / g-polymer] (after 40 minutes), and the water absorption with respect to physiological saline was 46 [g / g-polymer] (after 40 minutes). there were.

<Comparative Example 1> The same operation as in Example 3 was repeated to obtain a crosslinked product. Next, the crosslinked product was charged into a flask, and 30 g of methanol was added.
An attempt was made to separate the MF. 5. The recovered crosslinked polymer is 6.
5 g (DMF concentration: 53% by weight).

[Comparison and consideration of Examples 1 to 3 and Comparative example 1]
In Comparative Example 1, an attempt was made to separate the crosslinked polysuccinimide at a low temperature, but the DMF concentration in the crosslinked polymer was high.

In contrast, in Examples 1 to 3, the separation of crosslinked polysuccinimide at a high temperature resulted in DMF
A crosslinked polysuccinimide having a significantly reduced concentration was obtained. Furthermore, as a result of producing a water-absorbent resin from the crosslinked polymer having a significantly reduced DMF concentration, a water-absorbent resin having good water absorbability was obtained.

[0163]

According to the present invention, a method for producing a crosslinked polymer having a reduced solvent content can be provided. Further, the present invention can provide a method for producing a crosslinked polysuccinimide having a reduced solvent content.

Continued on the front page (72) Inventor Susumu Fukawa 580-32 Takuji Nagaura, Sodegaura City, Chiba Prefecture Inside Mitsui Chemicals Co., Ltd. (72) Inventor Toshio Kato 580-32 Takuji Nagaura, Sodegaura-shi, Chiba Mitsui Chemicals, Inc. (72) Inventor Makoto Sukegawa 580-32 Takuji Nagaura, Sodegaura-shi, Chiba 580-32 Mitsui Chemicals, Inc. (72) Invention Person Yoshihiro Iruri 580-32 Takuji Nagaura, Sodegaura City, Chiba Prefecture Inside Mitsui Chemicals, Inc.

Claims (12)

[Claims] 1. A method for producing a solvent-reduced crosslinked polysuccinimide, comprising: an organic solvent (primary solvent) for dissolving at least a part of an uncrosslinked polysuccinimide; and a primary solvent / crosslinking comprising the crosslinked polysuccinimide. A method for producing a solvent-reduced crosslinked polysuccinimide, comprising heating a polysuccinimide mixture to 50 to 300 ° C. and separating the mixture into a primary solvent-reduced crosslinked polysuccinimide and a primary solvent. 2. The method according to claim 1, wherein the operation of separating the primary solvent reduced crosslinked polysuccinimide and the primary solvent is at least one selected from the group consisting of extraction, drying, and solid-liquid separation. Item 4. The method for producing a solvent-reduced crosslinked polysuccinimide according to Item 1. 3. When the weight of the crosslinked polysuccinimide contained in the primary solvent reduced crosslinked polysuccinimide is WP and the weight of the primary solvent contained in the primary solvent reduced crosslinked polysuccinimide is WA, WP and WA Is represented by Formula (1), The method for producing a solvent-reduced crosslinked polysuccinimide according to claim 1 or 2, wherein 0% by weight ≤ {WA} (WP + WA)} x 100 ≤ 30% by weight (1) 4. The method for producing a solvent-reduced crosslinked polysuccinimide according to claim 1, wherein the primary solvent comprises an aprotic polar solvent. 5. The method for producing a solvent-reduced crosslinked polysuccinimide according to claim 4, wherein the aprotic polar solvent is N, N-dimethylformamide (DMF). 6. In the extraction, an extraction solvent (secondary solvent) that does not substantially dissolve uncrosslinked polysuccinimide and is compatible with the primary solvent is added to the primary solvent / crosslinked polysuccinimide mixture. The method for producing a solvent-reduced crosslinked polysuccinimide according to any one of claims 2 to 5, wherein the solvent is separated into a primary solvent-reduced crosslinked polysuccinimide and a primary solvent. 7. The method for producing a solvent-reduced crosslinked polysuccinimide according to claim 6, wherein the secondary solvent comprises an organic solvent and / or water. 8. An organic solvent comprising at least one organic solvent selected from the group consisting of alcohols having 1 to 20 carbon atoms, ketones having 3 to 20 carbon atoms, and ethers having 3 to 20 carbon atoms. The method for producing a solvent-reduced crosslinked polysuccinimide according to claim 7, comprising a solvent. 9. The solvent-reduced crosslinked polysuccinimide according to claim 8, wherein the organic solvent comprises at least one organic solvent selected from the group consisting of methanol, isopropyl alcohol, and acetone. Production method. 10. A solvent-reduced crosslinked polysuccinimide obtained by the production method according to claim 1. 11. A method for producing a crosslinked polyaspartic acid-based resin, wherein the imide ring structure in the solvent-reduced crosslinked polysuccinimide according to claim 10 is hydrolyzed. 12. A water-absorbing polymer obtained by the production method according to claim 11.