JP2003020363A - Crosslinking agent and water-absorptive resin using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crosslinking agent which is substantially comparable with an epoxy-containing crosslinking agent in excellent water-absorption and enables to avoid from a skin stimulation trouble; and a water-absorptive resin using the same. SOLUTION: The crosslinking agent comprises having at least two hydroxy ester units instead of epoxy groups in the molecular structure. The water- absorptive resin can be produced by using the crosslinking agent and brings about no skin stimulation trouble to show excellent water-absorption.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a cross-linking agent and a water-absorbent resin using the same. More specifically, the present invention relates to a cross-linking agent and a water-absorbent resin using the same, which can provide excellent water absorption and can avoid problems with skin irritation in producing a water-absorbent resin.

[0002]

2. Description of the Related Art In recent years, water-absorbent resins have been widely used for the purpose of absorbing body fluids in hygiene products such as so-called incontinence pads represented by paper diapers and sanitary napkins. As the water absorbent resin, for example, partially neutralized polyacrylic acid, starch-acrylic acid graft polymer,
Examples thereof include a crosslinked product, a saponified product or a hydrolyzate of a hydrophilic resin such as a vinyl acetate-acrylic acid ester copolymer, an acrylonitrile copolymer, an acrylamide copolymer.

In hygiene products, these water-absorbent resins are
Excellent in water absorption, absorption rate, liquid permeability, gel strength of swollen gel, and suction force when sucking water from a base material containing liquid when contacted with an aqueous liquid in body fluid It is necessary to have characteristics.

However, in the above water-absorbent resin, the relationship between these characteristics does not always show a positive correlation.
For example, the conventional water-absorbent resin has a problem that the higher the absorption capacity without load, the lower the absorption property under load.

As a method for improving the properties of the water-absorbent resin in a well-balanced manner, a technique of cross-linking the vicinity of the surface of the water-absorbent resin is known. As an example of such a technique, a method using a polyhydric alcohol as a cross-linking agent (JP-A-58-180).
233 and JP-A-61-16903);
Method using polyvalent glycidyl compound, polyvalent aziridine compound, polyvalent amine compound and / or polyvalent isocyanate compound (JP-A-59-189103); method using glyoxysal (JP-A-52-117393)
Japanese Patent Laid-Open Publication No. 51-136);
588, JP-A-61-257235, JP-A-62-7745); Method using a silane coupling agent (JP-A-61-211305, JP-A-61-211305)
JP-A 1-252212 and JP-A 61-26400.
No. 6); and a method using alkylene carbonate (German Patent No. 4020780).

Further, a method of allowing an inert inorganic powder to be present as a third substance for the purpose of improving the dispersibility of the cross-linking agent during the mixing or the cross-linking reaction of the cross-linking agent (JP-A-60-16395).
No. 6 and JP-A No. 60-255814); A method of allowing a dihydric alcohol to be present (JP-A-1-29200).
4); a method of allowing water and an ether compound to be present (JP-A-2-153903); a method of allowing an alkylene oxide adduct of a monohydric alcohol, an organic acid salt, a lactam, etc. to be present (European Patent No. 555692) ); A method in which phosphoric acid is allowed to exist (Japanese Patent Publication No. 8-508517) is also known.

However, the conventional technique for crosslinking the surface of the water-absorbent resin has a problem that it cannot sufficiently meet the required performance of the recent highly sophisticated water-absorbent resin. For example,
In recent years, hygiene products have tended to be made thinner. Therefore, the water-absorbent resin concentration in the absorbent body is high for each hygiene article. Therefore, in an absorber containing a large amount (that is, a high concentration) of a water-absorbent resin, the characteristics desired for the water-absorbent resin are a balance between the absorption capacity under no pressure and the absorption capacity under high pressure. You need to be good.

Further, the crosslinking agent used itself has a problem of safety.

Conventionally, it has been known to use a crosslinking agent having a highly reactive group of an epoxy group in the production of a water absorbent resin. However, this type of cross-linking agent has skin irritation, and in addition to the problem of working environment, it is necessary to strictly control the residual amount in the resin in consideration of application to sanitary products. In addition, when using this type of cross-linking agent, a complicated operation was required in the process in order to reduce the residual amount.

On the other hand, in the production of water-absorbent resin, it is also known to use a polyhydric alcohol, which is relatively safe, as a crosslinking agent against problems such as skin irritation. However, this type of crosslinker is generally less reactive,
It is necessary to manufacture the water absorbent resin at a high temperature. As a result, the water absorbent resin may be deteriorated or its physical properties may be deteriorated during the crosslinking reaction.

[0011]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above problems, and an object thereof is to provide excellent water absorption almost equal to that of a crosslinking agent having an epoxy group. And to provide a cross-linking agent and a water-absorbent resin using the same, which can avoid the problem of skin irritation.

[0012]

The present invention is a crosslinking agent, which is a compound represented by the following general formula (I):

[0013]

[Chemical 9]

Where n is an integer from 2 to 6; R ₁
Is a linear, branched or cyclic n-valent hydrocarbon group having 1 to 20 carbon atoms, which may be substituted with a hydroxyl group; and R ₂ to R ₅ are each independently to, -H, -CH ₃ or is _-CH 2 OH; containing a crosslinking agent.

In a preferred embodiment, the hydrocarbon group is a group selected from the group consisting of aromatic hydrocarbon group, aliphatic hydrocarbon group, and alicyclic hydrocarbon group.

In a preferred embodiment, among the compounds represented by the above general formula (I), n is an integer of 2 to 4 and R ₁ is substituted with a hydroxyl group having 6 carbon atoms. Contains a compound which is a good n-valent aromatic hydrocarbon group.

In a preferred embodiment, in the compound represented by the above general formula (I), n is an integer of 2 to 6 and R ₁ is substituted with a hydroxyl group having 1 to 20 carbon atoms. It contains a compound which is an n-valent aliphatic hydrocarbon group which may be incorporated.

In a preferred embodiment, R _{1 of the} above compound is —CH ₂ —, —CH ₂ CH ₂ —, —CH ₂ C.
_{H 2 CH 2 -, - CH} 2 CH 2 CH 2 CH 2 -, - CH
_{(OH) CH 2 -, -} CH (OH) CH (OH) -,

[0019]

[Chemical 10]

Is a group selected from the group consisting of

In a preferred embodiment, the compound is N, N'-bis (2-hydroxyethyl) ethanediamide, N, N'-bis (2-hydroxy-1,1-dimethylethyl) ethanediamide, N, N '-Bis [2-
Hydroxy-1,1-bis (hydroxymethyl) ethyl] ethanediamide, N, N′-bis (2-hydroxyethyl) propanediamide, N, N′-bis (2-hydroxy-1,1-dimethylethyl) propanediamide ,
N, N'-bis (2-hydroxyethyl) butanediamide, N, N'-bis (2-hydroxyethyl) pentanediamide, N, N'-bis (2-hydroxyethyl) hexanediamide, 2-hydroxy-N, N'-bis (2
-Hydroxyethyl) butanediamide, 2,3-dihydroxy-N, N'-bis (2-hydroxyethyl) butanediamide, and N, N'-bis (2-hydroxyethyl) -1,4-benzenedicarboxamide It contains at least one selected from the group.

The present invention is also a cross-linking agent, which is represented by the following general formula (I '):

[0023]

[Chemical 11]

[0024] Here, the _{'R 5 from'} from _{R 2 R 5} and R _2, each independently, -H, -CH ₃ or -
CH ₂ OH;

The present invention is also a cross-linking agent, which is represented by the following general formula (II):

[0026]

[Chemical 12]

Where n is an integer from 2 to 6; R ₁
Is a linear, branched or cyclic n-valent hydrocarbon group having 1 to 20 carbon atoms, which may be substituted with a hydroxyl group; and R ₆ to R ₉ are each independently. to, -H, -CH ₃ or is _-CH 2 OH; containing a crosslinking agent.

[0028] In a preferred embodiment, the hydrocarbon group is a group selected from the group consisting of an aromatic hydrocarbon group, an aliphatic hydrocarbon group, and an alicyclic hydrocarbon group.

In a preferred embodiment, among the compounds represented by the above general formula (II), n is an integer of 2 to 4 and R ₁ is substituted with a hydroxyl group having 6 carbon atoms. It may be an n-valent aromatic hydrocarbon group,
Contains a compound.

In a preferred embodiment, in the compound represented by the above general formula (II), n is an integer of 2 to 6 and R ₁ is substituted with a hydroxyl group having 1 to 20 carbon atoms. It contains a compound which is an n-valent aliphatic hydrocarbon group which may be incorporated.

In a preferred embodiment, R _{1 of the} above compound is —CH ₂ —, —CH ₂ CH ₂ —, —CH ₂ C.
_{H 2 CH 2 -, - CH} 2 CH 2 CH 2 CH 2 -, - CH
_{(OH) CH 2 -, -} CH (OH) CH (OH) -,

[0032]

[Chemical 13]

It is a group selected from the group consisting of:

In a preferred embodiment, the compound is 4,4 ', 5,5'-tetrahydro-4,4.
4 ′, 4′-tetramethyl-2,2′-bisoxazole, 2,2 ′-(1,3-propanediyl) bis [4,
5-dihydro-4,4-dimethyloxazole], 2,
2 '-(1,4-butanediyl) bis [4,5-dihydro-4,4-dimethyloxazole], and 2,2'
-(1,2-ethanediyl) bis [4,5-dihydro-
At least one selected from the group consisting of 4,4-dimethyloxazole].

The present invention is also a water-absorbent resin obtained by crosslinking a hydrophilic resin, the crosslinking being represented by the following general formula (II
Structure represented by I):

[0036]

[Chemical 14]

(Where n is an integer from 2 to 6; R
₁ is a linear, branched or cyclic n-valent hydrocarbon group having 1 to 20 carbon atoms, which may be substituted with a hydroxyl group; and R ₂ to R ₅ are respectively independently, -H, a -CH ₃ or _-CH 2 OH)
Is a water-absorbent resin.

In a preferred embodiment, the hydrocarbon group is a group selected from the group consisting of aromatic hydrocarbon groups, aliphatic hydrocarbon groups, and alicyclic hydrocarbon groups.

In a preferred embodiment, the bridge is an n-valent aromatic hydrocarbon optionally substituted with a hydroxyl group, wherein n is an integer of 2 to 4 and R ₁ has 6 carbon atoms. It has a structure that is a group.

In a preferred embodiment, the crosslinks are such that n is an integer from 2 to 6 and R ₁ is from 1 to 2.
It has a structure which is an n-valent aliphatic hydrocarbon group which may be substituted with a hydroxyl group having 0 carbon atoms.

In a preferred embodiment, R ₁ is-
_{CH 2 -, - CH 2 CH} 2 -, - CH 2 CH 2 CH
_{2 -, - CH 2 CH 2} CH 2 CH 2 -, - CH (OH)
_{CH 2 -, - CH (OH} ) CH (OH) -,

[0042]

[Chemical 15]

It is a group selected from the group consisting of:

In a preferred embodiment, the hydrophilic resin is selected from the group consisting of modified polyacrylic acid and its derivative, modified polylactic acid and its derivative, modified polyglutamic acid and its derivative, and modified polyaspartic acid and its derivative. At least one resin to be used.

The present invention is also a water-absorbent resin obtained by crosslinking a hydrophilic resin, the crosslinking being represented by the following general formula (II
Structure represented by I '):

[0046]

[Chemical 16]

(Wherein R ₂ to R ₅ and R _{2 ′} to R _{5 ′} are each independently —H, —CH ₃ or —CH ₂ OH).

In a preferred embodiment, the hydrophilic resin is selected from the group consisting of modified polyacrylic acid and its derivatives, modified polylactic acid and its derivatives, modified polyglutamic acid and its derivatives, and modified polyaspartic acid and its derivatives. At least one resin to be used.

The present invention is also a water-absorbent resin obtained by crosslinking with a crosslinking agent containing the compound represented by the general formula (I).

The present invention is also a water-absorbent resin obtained by crosslinking with a crosslinking agent containing a compound represented by the above general formula (I ').

The present invention is also a water-absorbent resin obtained by crosslinking with a crosslinking agent containing the compound represented by the general formula (II ').

The present invention is also a method for producing a water absorbent resin, which comprises mixing a hydrophilic resin and a crosslinking agent containing a compound represented by the above general formula (I); Heating the mixture;

The present invention also provides a method for producing a water absorbent resin, which comprises mixing a hydrophilic resin with a crosslinking agent containing a compound represented by the above general formula (I); and Heating the mixture;

The present invention also provides a method for producing a water absorbent resin, which comprises mixing a hydrophilic resin with a crosslinking agent containing a compound represented by the above general formula (II); Heating the mixture;

[0055]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.

The first cross-linking agent of the present invention contains a compound represented by the following general formula (I):

[0057]

[Chemical 17]

Where n is an integer from 2 to 6; R ₁
Is a linear, branched or cyclic n-valent hydrocarbon group having 1 to 20 carbon atoms, which may be substituted with a hydroxyl group; and R ₂ to R ₅ are each independently. to, -H, a -CH ₃ or _-CH 2 OH. Here, the term "linear, branched or cyclic n-valent hydrocarbon group optionally substituted with a hydroxyl group" used in the present specification means a linear, branched or cyclic group. The following n-valent hydrocarbon group is meant to include a group composed only of carbon atoms and hydrogen atoms, and a group in which a part of hydrogen atoms in the hydrocarbon group are substituted with a hydroxyl group.

Examples of the hydrocarbon group represented by R ₁ in the above general formula (I) include an aromatic hydrocarbon group, an aliphatic hydrocarbon group, and an alicyclic hydrocarbon group, and more preferable. Is an aromatic hydrocarbon group containing 6 to 20 carbon atoms, an aliphatic hydrocarbon group having 1 to 20 carbon atoms, and an alicyclic carbon group having 3 to 20 carbon atoms. A hydrogen group is mentioned.

Further, the compound represented by the above general formula (I)
In preferred R₁As an example of, 6 to 20,
Preferably having 6 to 15 carbon atoms and unsubstituted
Or n which may be substituted with 1 to 2 hydroxyl groups
Valent aromatic hydrocarbon groups; as well as 1-20, preferred
Has 1 to 10 carbon atoms and is unsubstituted or
Is an n-valent oil which may be substituted with 1 to 4 hydroxyl groups.
An aliphatic hydrocarbon group; More preferred R₁of
As an example, -CH_Two-, -CH_TwoCH_Two-, -CH_Two
CH_TwoCH_Two-, -CH_TwoCH_TwoCH_TwoCH_Two-, -C
H (OH) CH _Two-, -CH (OH) CH (OH)-,

[0061]

[Chemical 18]

And the like.

In the present invention, among the compounds represented by the above general formula (I), n is 2 to 4 in the above general formula (I) because the compound itself is easily available and / or synthesized. A compound having an n-valent aromatic hydrocarbon group optionally substituted with a hydroxyl group, wherein R ₁ has 6 carbon atoms; and n in the above general formula (I) is from 2 to 6 A compound having an n-valent aliphatic hydrocarbon group optionally substituted with a hydroxyl group, which is an integer of ₁ and R ₁ has 1 to 20 carbon atoms. Examples of these more preferable compounds include N, N'-bis (2-hydroxyethyl) ethanediamide and N, N'-bis (2-hydroxy-1,1-
Dimethylethyl) ethanediamide, N, N'-bis [2
-Hydroxy-1,1-bis (hydroxymethyl) ethyl] ethanediamide, N, N'-bis (2-hydroxyethyl) propanediamide, N, N'-bis (2-hydroxy-1,1-dimethylethyl) propane Diamide,
N, N'-bis (2-hydroxyethyl) butanediamide, N, N'-bis (2-hydroxyethyl) pentanediamide, N, N'-bis (2-hydroxyethyl) hexanediamide, 2-hydroxy-N, N'-bis (2
-Hydroxyethyl) butanediamide, 2,3-dihydroxy-N, N'-bis (2-hydroxyethyl) butanediamide, and N, N'-bis (2-hydroxyethyl) -1,4-benzenedicarboxamide. To be Particularly, N, N'-bis (2-hydroxyethyl) butanediamide is preferable.

These compounds are either commercially available or can be easily synthesized by those skilled in the art.

In the first cross-linking agent of the present invention, the compound represented by the general formula (I) may be used alone or in combination of a plurality of types, or may be represented by the general formula (I ') described later. The compound represented and / or the general formula (I
It may be contained in combination with the compound represented by I). When plural kinds of the compounds are used in combination, their composition ratio can be appropriately selected by those skilled in the art.

The second crosslinking agent of the present invention contains a compound represented by the following general formula (I '):

[0067]

[Chemical 19]

Here, R ₂ to R ₅ and R _{2 ′} to R _{5 ′} are each independently —H, —CH ₃ or —.
CH ₂ OH. Examples of the compound represented by the general formula (I ′) include N, N′-bis (2-hydroxyethyl) oxalic acid amide and N, N′-bis (1,1-).
Dimethyl-2-hydroxyethyl) oxalic acid amide, and N, N′-bis (trihydroxymethylmethyl) oxalic acid amide. These compounds are either commercially available or can be easily synthesized by those skilled in the art. In particular, N, N′-bis (2-) is provided because it provides an excellent crosslinking density with the hydrophilic resin described below, and the compound itself is relatively easy to obtain and / or synthesize.
Hydroxyethyl) oxalic acid amide is preferred.

In the second cross-linking agent of the present invention, the compound represented by the general formula (I ′) may be used alone or in combination of a plurality of types, or may be represented by the general formula (I).
And / or a general formula (I
It may be contained in combination with the compound represented by I). When plural kinds of the compounds are used in combination, their composition ratio can be appropriately selected by those skilled in the art.

The third crosslinking agent of the present invention contains a compound represented by the following general formula (II):

[0071]

[Chemical 20]

Where n is an integer from 2 to 6; R ₁
Is a linear, branched or cyclic n-valent hydrocarbon group having 1 to 20 carbon atoms, which may be substituted with a hydroxyl group; and R ₆ to R ₉ are each independently. to, -H, a -CH ₃ or _-CH 2 OH.

Examples of the hydrocarbon group represented by R ₁ in the above general formula (II) include an aromatic hydrocarbon group, an aliphatic hydrocarbon group, and an alicyclic hydrocarbon group, more preferably Is an aromatic hydrocarbon group containing 6 to 20 carbon atoms, an aliphatic hydrocarbon group having 1 to 20 carbon atoms, and an alicyclic carbon group having 3 to 20 carbon atoms. A hydrogen group is mentioned.

In the compound represented by the general formula (II), preferable examples of R ₁ are 6 to 20
, Preferably 6 to 15 carbon atoms, and an n-valent aromatic hydrocarbon group which may be unsubstituted or substituted with 1 to 2 hydroxyl groups; and 1 to 20 , An n-valent aliphatic hydrocarbon group which preferably has 1 to 10 carbon atoms and may be unsubstituted or substituted with 1 to 4 hydroxyl groups. More preferred R
Examples of _{1, -CH 2 -, - CH} 2 CH 2 -, - C
_{H 2 CH 2 CH 2 -,} - CH 2 CH 2 CH 2 CH 2 -,
_{-CH (OH) CH 2 -,} - CH (OH) CH (OH)
-,

[0075]

[Chemical 21]

Examples include

In the present invention, among the compounds represented by the above general formula (II), the compound itself can be obtained and / or
Alternatively, from the viewpoint of easy synthesis, n in the general formula (II) is an integer of 2 to 4, and R ₁ has 6 carbon atoms, and is an n-valent aromatic group which may be substituted with a hydroxyl group. A compound having a group hydrocarbon group; and n in the general formula (II) is an integer of 2 to 6, and R ₁
A compound having an n-valent aliphatic hydrocarbon group optionally having a hydroxyl group, having 1 to 20 carbon atoms;
Is more preferable.

Examples of these more preferable compounds include 4,4 ', 5,5'-tetrahydro-4,4.
4 ′, 4′-tetramethyl-2,2′-bisoxazole, 2,2 ′-(1,3-propanediyl) bis [4,
5-dihydro-4,4-dimethyloxazole], 2,
2 '-(1,4-butanediyl) bis [4,5-dihydro-4,4-dimethyloxazole], and 2,2'
-(1,2-ethanediyl) bis [4,5-dihydro-
4,4-dimethyloxazole]. Particularly, 2,2 '-(1,4-butanediyl) bis [4,5-dihydro-4,4-dimethyloxazole] is preferable.

These compounds are either commercially available or can be easily synthesized by those skilled in the art.

In the third cross-linking agent of the present invention, the compound represented by the general formula (II) may be used alone or in combination of a plurality of types, or may be represented by the general formula (I).
It may be contained in combination with the compound represented by and / or the compound represented by the general formula (I ′). When plural kinds of the compounds are used in combination, their composition ratio can be appropriately selected by those skilled in the art.

As described above, at least the compound represented by the general formula (I), the compound represented by the general formula (I ′) and the compound represented by the general formula (II) are at least in the structure. It has two hydroxy ester amide units or an oxazoline unit that can form a hydroxy ester amide unit upon ring opening. With these units, the crosslinking agent for a water-absorbent resin of the present invention can react with at least two carboxyl groups in the hydrophilic resin described later to crosslink the resin.

The water absorbent resin of the present invention will be described below.

The water-absorbent resin of the present invention is a water-absorbent resin obtained by cross-linking a hydrophilic resin, the cross-linking being represented by the following general formula (III):

[0084]

[Chemical formula 22]

(Where n is an integer from 2 to 6; R
₁ is a linear, branched or cyclic n-valent hydrocarbon group having 1 to 20 carbon atoms, which may be substituted with a hydroxyl group; and R ₂ to R ₅ are respectively independently, -H, a -CH ₃ or _-CH 2 OH)
Have. Preferred examples of R ₁ are the same as above.

Alternatively, the water-absorbent resin of the present invention is a water-absorbent resin obtained by cross-linking a hydrophilic resin, and the cross-linking has a structure represented by the following general formula (III ′):

[0087]

[Chemical formula 23]

(Wherein R ₂ to R ₅ and R _{2 ′} to R _{5 ′} are each independently —H, —CH ₃ or —CH ₂ OH).

In the water absorbent resin of the present invention, the crosslinked structure represented by the general formula (III) and the general formula (II
Either one or both of the crosslinked structure represented by I ′) may be contained.

The hydrophilic resin used in the present invention is preferably 50 times to 1 times by weight in ion-exchanged water.
It is a known resin having a carboxyl group on the polymer chain, which is capable of absorbing 000 times as much water and forming a hydrogel. Examples of such hydrophilic resins include polyacrylic acid and its derivatives, polylactic acid and its derivatives, polyglutamic acid and its derivatives, polyaspartic acid and its derivatives, and combinations thereof.

The hydrophilic resin used in the present invention may also be a modified or unmodified resin. here,
The term "modified" used in the present specification refers to a state in which it has already been internally crosslinked with another crosslinking agent (internal crosslinking agent) described later. In the present invention, the modified hydrophilic resin is more preferable. Examples of such modified hydrophilic resins include modified polyacrylic acid and its derivatives; modified polylactic acid and its derivatives; modified polyglutamic acid and its derivatives; modified polyaspartic acid and its derivatives;
And combinations thereof. In particular, modified polyacrylic acid and its derivatives are preferred because of their high versatility as water-absorbent resins.

Polyacrylic acid and its derivative can be obtained typically by polymerizing a hydrophilic monomer whose main component is acrylic acid and / or its salt (neutralized product).

Examples of the acrylic acid salts include alkali metal salts of acrylic acid, ammonium salts, amine salts and the like. The above polyacrylic acid and its derivative are composed of 10 mol% to 40 mol% acrylic acid and 90 mol% to 60 mol% acrylic acid salt (provided that
The total amount of both is 100 mol%). When a hydrophilic resin containing acrylic acid and / or a derivative thereof as a main component is polymerized to obtain a hydrophilic resin, it may be used in combination with these acrylic acid or a salt thereof, if necessary, other than acrylic acid. It may contain a monomer.

The kind of the monomer other than acrylic acid is not particularly limited, but specifically, for example, methacrylic acid, maleic acid, vinyl sulfonic acid, styrene sulfonic acid, 2
-(Meth) acrylamido-2-methylpropanesulfonic acid, 2- (meth) acryloylethanesulfonic acid, 2
Anionic unsaturated monomer such as (meth) acryloylpropanesulfonic acid and salts thereof; acrylamide, methacrylamide, N-ethyl (meth) acrylamide, Nn-propyl (meth) acrylamide, N-isopropyl (meth) Acrylamide, N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxypolyethylene glycol (meth)
Acrylate, polyethylene glycol mono (meth) acrylate, vinyl pyridine, N-vinyl pyrrolidone,
Nonionic hydrophilic group-containing unsaturated monomers such as N-acryloylpiperidine and N-acryloylpyrrolidine; N,
N-dimethylaminoethyl (meth) acrylate, N,
N-diethylaminoethyl (meth) acrylate, N,
N-dimethylaminopropyl (meth) acrylate,
Included are cationic unsaturated monomers such as N, N-dimethylaminopropyl (meth) acrylamide, and their quaternary salts. These monomers may be used alone, or may be used by mixing two or more kinds as necessary.

When a monomer other than acrylic acid is used in the hydrophilic resin, the monomer other than acrylic acid is added to the total amount of acrylic acid and / or its derivative used as the main component. , Preferably 30 mol% or less, more preferably 10 mol% or less. By using the monomer other than acrylic acid in such a range, the water absorbing property of the water absorbent resin of the present invention obtained is further improved, and the water absorbent resin can be obtained at a lower cost.

As the hydrophilic resin used in the present invention, for example, bulk polymerization or precipitation polymerization can be carried out when polymerizing a hydrophilic monomer containing acrylic acid and / or its derivative as a main component. is there. On the other hand, it is preferable to carry out aqueous solution polymerization or reverse phase suspension polymerization using an aqueous solution of the hydrophilic monomer, from the viewpoint of excellent performance and easy control of polymerization. In addition, when the aqueous solution of the hydrophilic monomer is used, the concentration of the monomer in the aqueous solution (hereinafter, referred to as an aqueous monomer solution) is not particularly limited, but is preferably 10% by weight to 70% by weight. It is within the range, and more preferably within the range of 20% by weight to 40% by weight. Further, when performing the aqueous solution polymerization or reverse phase suspension polymerization,
A solvent other than water may be used in combination as necessary, and the type of solvent used in combination is not particularly limited.

When initiating the above polymerization, for example,
Potassium persulfate, ammonium persulfate, sodium persulfate, t-butyl hydroperoxide, hydrogen peroxide,
A radical polymerization initiator such as 2,2′-azobis (2-aminodipropane) dihydrochloride can be used. Furthermore, by using together with a reducing agent that accelerates the decomposition of these polymerization initiators, it is possible to use both as a redox initiator. Examples of the reducing agent include (bis) sulfite (salt) such as sodium sulfite and sodium bisulfite, L-ascorbic acid (salt), reducing metal (salt) such as ferrous salt, amines and the like. However, the present invention is not limited to these.

The amount of these polymerization initiators used is preferably 0.001 to 2 mol%, more preferably 0.01 to 2 mol%.
It is mol% -0.1 mol%. If the amount of these polymerization initiators used is less than 0.001 mol%, the amount of unreacted monomers increases, and the amount of residual monomers in the resulting water absorbent resin may increase. On the other hand, if the amount of these polymerization initiators used exceeds 2 mol%, the amount of water-soluble components in the resulting water absorbent resin may increase.

The polymerization reaction may be initiated by irradiating the reaction system with active energy rays such as radiation, electron beams and ultraviolet rays. The reaction temperature in the above polymerization reaction is not particularly limited, but is preferably 20 ° C to 90 ° C.
℃. Further, the reaction time is not particularly limited and may be appropriately set depending on the types of the hydrophilic monomer and the polymerization initiator, the reaction temperature and the like.

When a modified resin is used as the hydrophilic resin used in the present invention, an internal cross-linking agent having two or more polymerizable unsaturated groups and / or two or more reactive groups in one molecule is used. Those polymerized or reacted are more preferable. Specific examples of these internal crosslinking agents include N, N-methylenebis (meth) acrylamide, (poly) ethylene glycol (meth) acrylate, (poly) propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, Glycerin tri (meth) acrylate, glycerin acrylate methacrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, pentaerythritol hexa (meth) acrylate, triallyl cyanurate, triallyl isocyanurate, triallyl phosphate,
Triallylamine, poly (meth) allyloxyalkane,
(Poly) ethylene glycol diglycidyl ether, glycerol diglycidyl ether, ethylene glycol, polyethylene glycol, propylene glycol,
Glycerin, pentaerythritol, ethylenediamine, ethylene carbonate, propylene carbonate,
Examples include polyethyleneimine, and glycidyl (meth) acrylate.

These internal cross-linking agents may be used alone or, if necessary, as a mixture of two or more kinds.
Further, these internal cross-linking agents may be added to the reaction system all at once or may be added in portions. When using two or more kinds of internal cross-linking agents, it is preferable to essentially use a compound having two or more polymerizable unsaturated groups in consideration of the water absorption property of the resulting hydrophilic resin.

The amount of these internal cross-linking agents used is preferably in the range of 0.005 mol% to 2 mol%, and 0.01 mol% to 1 mol% with respect to the hydrophilic monomer. It is more preferable to set it within the range. When the amount of the internal cross-linking agent used is out of the range of 0.005 mol% to 2 mol%, the hydrophilic resin itself may not have satisfactory water absorption properties.

When the crosslinked structure is introduced into the hydrophilic resin by using the internal crosslinking agent, the internal crosslinking agent is reacted during or after the polymerization of the hydrophilic monomer or after the polymerization or neutralization. It may be added to the system. In the above polymerization, various foaming agents such as carbonic acid (hydrogen) salt, carbon dioxide, azo compound, and inert organic solvent are added to the reaction system; starch / cellulose, starch / cellulose derivatives, polyvinyl alcohol, polyacrylic acid ( Salt), polyacrylic acid (salt)
You may add hydrophilic polymers, such as a crosslinked body, various surfactants, and chain transfer agents, such as hypophosphorous acid (salt).

The water-absorbent resin of the present invention has the above general formula (II
I) and / or the above general formula (I)
By having the crosslinked structure represented by II ′), the production thereof does not particularly require a reaction at a high temperature. Further, since it has no epoxy group in its structure, the problem of skin irritation can be avoided.

The water absorbent resin of the present invention is manufactured as follows.

First, the modified or unmodified hydrophilic resin, the compound represented by the general formula (I), the compound represented by the general formula (I ′), and / or the general formula (II). The compound represented by (the crosslinking agent of the present invention) is mixed.

The mixing ratio of the hydrophilic resin and the cross-linking agent is not particularly limited and can be arbitrarily set by those skilled in the art.

As a specific example, when an internally crosslinked (modified) hydrophilic resin is used (that is, when the crosslinking agent of the present invention is used as a surface crosslinking agent), 100 parts by weight of the hydrophilic resin is used. On the other hand, the crosslinking agent of the present invention is preferably 0.001 to 20 parts by weight. When the amount of the crosslinking agent of the present invention to be mixed is less than 0.001 part by weight,
The resulting water absorbent resin may not have sufficient water absorption and water absorption rate. The amount of the crosslinking agent of the present invention to be mixed is 2
If it exceeds 0 parts by weight, a large amount of unreacted crosslinking agent may remain in the water absorbent resin, resulting in poor economy, and / or the crosslinking density becoming too high, so that the resin obtained has sufficient water absorption and water absorption. Problems such as lack of speed may occur.

On the other hand, when the cross-linking agent of the present invention is used as the internal cross-linking agent, the cross-linking agent of the present invention is preferably 0.005 parts by weight to 1 part by weight with respect to 100 parts by weight of the unmodified hydrophilic resin.
It is 0 part by weight, and more preferably 0.01 part by weight to 5 parts by weight. The amount of the crosslinking agent of the present invention mixed is 0.00
If the amount is less than 5 parts by weight, the resulting water absorbent resin may not have sufficient water absorbency. If the amount of the cross-linking agent of the present invention to be mixed exceeds 10 parts by weight, there is a possibility that a large amount of unreacted cross-linking agent remains in the water absorbent resin, resulting in poor economy and / or too high cross-linking density The resulting resin may have problems such as not having sufficient water absorption and water absorption rate.

Usually, the hydrophilic resin and the crosslinking agent of the present invention are mixed by, for example, a cylindrical mixer, a V-shaped mixer, a ribbon mixer, a screw mixer, a double-arm mixer, and a pulverizer. Sufficient stirring is preferably performed using a mold kneader or the like. This is because the cross-linking agent of the present invention is uniformly dispersed among the molecules of the hydrophilic resin by performing sufficient stirring.

Further, when the hydrophilic resin is surface-crosslinked using the crosslinking agent of the present invention, the above mixing is preferably carried out in water, a hydrophilic organic solvent or a solvent consisting of a combination thereof. Specifically, the crosslinking agent of the present invention is previously dissolved in this solvent, and then the obtained solution and the hydrophilic resin are mixed. Examples of hydrophilic organic solvents used in such a mixture include lower aliphatic alcohols such as methanol, ethanol, n-propyl alcohol and isopropyl alcohol; ketones such as acetone;
Ethers such as dioxane, tetrahydrofuran and methoxy (poly) ethylene glycol; and amides such as ε-caprolactam and N, N-dimethylformamide.

The amount of the hydrophilic organic solvent is not particularly limited depending on the kind of the hydrophilic resin used, particle size, water content, etc., but is preferably 0.1 with respect to 100 parts by weight of the solid content of the hydrophilic resin. The range is from 20 to 20 parts by weight, more preferably from 0.5 to 10 parts by weight.

After mixing, the mixture containing the hydrophilic resin and the crosslinking agent of the present invention is heated. The heating temperature is not particularly limited, but is preferably 40 ° C to 250 ° C, more preferably 70 ° C to 200 ° C. The time required for heating is also not particularly limited, but is preferably 0.2 hours to 3 hours.

By performing the above heating, in the crosslinking agent of the present invention, at least two hydroxyesteramide units contained in the structure react with the carboxyl group in the hydrophilic resin, and as a result, the general formula (III) And / or forms a crosslinked structure represented by (III ′).

Thus, the water absorbent resin of the present invention having a crosslinked structure represented by the general formula (III) and / or (III ′) is produced. In the water absorbent resin of the present invention, a disinfectant, for the purpose of imparting various functions,
Deodorants, antibacterial agents, fragrances, various inorganic powders, foaming agents, pigments, dyes, hydrophilic short fibers, fertilizers, oxidizing agents, reducing agents, water,
And other additives such as salts may be contained. The amount and timing of addition of these other additives are appropriately selected by those skilled in the art.

Further, in the water-absorbent resin of the present invention, together with the above-mentioned crosslinking agent of the present invention, another surface-crosslinking agent which has been conventionally known is used in combination within the range where the effect of surface crosslinking by the crosslinking agent is not hindered. Good. Examples of such other surface cross-linking agents include polyhydric alcohol compounds, polyvalent amine compounds, polyisocyanate compounds, polyvalent oxazoline compounds, alkylene carbonate compounds, silane coupling agents, polyvalent metal compounds and combinations thereof. Is mentioned. Further, an epoxy compound, a haloepoxy compound, and a combination thereof may be used in combination as long as they do not adversely affect the human body.

Examples of such polyhydric alcohol compounds are ethylene glycol, diethylene glycol, propylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, 1,3.
-Propanediol, dipropylene glycol, 2,
2,4-trimethyl-1,3-pentanediol, polypropylene glycol, glycerin, polyglycerin,
2-butene-1,4-diol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,2- Cyclohexanol, trimethylolpropane, diethanolamine, triethanolamine, polyoxypropylene, oxyethylene-oxypropylene block copolymers, pentaerythritol and sorbitol, and combinations thereof.

Examples of the polyvalent amine compound include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and polyethyleneimine, and their inorganic or organic salts (eg, azithinium salt),
These combinations are mentioned.

Examples of the above polyisocyanate compound include 2,4-tolylene diisocyanate and hexamethylene diisocyanate, and combinations thereof.

Examples of the polyvalent oxazoline compound include 1,2-ethylenebisoxazoline.

Examples of the alkylene carbonate compound include 1,3-dioxolan-2-one, 4-methyl-1,3-dioxolan-2-one and 4,5-dimethyl-1,3-dioxolane-2-. On, 4,4-dimethyl-1,3-dioxolan-2-one, 4-ethyl-1,
3-dioxolan-2-one, 4-hydroxymethyl-
1,3-dioxolan-2-one, 1,3-dioxan-2-one, 4-methyl-1,3-dioxan-2-one, 4,6-dimethyl-1,3-dioxan-2-one and 1,3-dioxoban-2-one, as well as combinations thereof.

Examples of the above silane coupling agent include:
γ-glycidoxypropyltrimethoxysilane and γ
-Aminopropyltriethoxysilane, as well as combinations thereof.

Examples of the polyvalent metal compound include zinc,
Hydroxides and chlorides of metals such as calcium, magnesium, aluminum, iron and zirconium,
The combination of them is mentioned.

Examples of the epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether. Ether and glycidol,
And combinations thereof.

Examples of the haloepoxy compound include epichlorohydrin, epibromhydrin and α-methylepichlorohydrin, and their polyvalent amine adducts (for example, Kamen (registered trademark) manufactured by Hercules). , And combinations thereof.

When the cross-linking agent of the present invention is used in combination with the above-mentioned other surface cross-linking agent, the composition ratio thereof can be appropriately selected by those skilled in the art within the range that the effect of the surface cross-linking by the cross-linking agent of the present invention is not hindered.

The water absorbent resin of the present invention has excellent water absorbability. Furthermore, since it has no skin irritation, the user can use it with confidence. The water absorbent resin of the present invention is useful as an absorbent for hygiene products such as disposable diapers and sanitary napkins.

[0128]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

<Production Example 1: Synthesis of N, N'-bis (2-hydroxyethyl) ethanediamide> A 100 mL glass reactor was charged with 13.4 g (0.22 mol) of aminoethanol and 30 g of methanol. The solution was stirred at room temperature. Then 11.8 g in this solution
(0.10 mol) dimethyl oxalate was slowly added dropwise. After the dropping, the solution was stirred at room temperature for 2 hours. Further, 30 g of toluene was added to this solution, and methanol was removed under reduced pressure. The obtained crystals were collected by filtration and dried under reduced pressure to obtain 17.3 g of white crystals.

The white crystals were analyzed by ¹ H-NMR. The results of ¹ H-NMR analysis are shown in Table 1.

[0131]

[Table 1]

From the results, it was confirmed that the obtained white crystals were the title compound.

<Production Example 2: Synthesis of N, N'-bis (2-hydroxy-1,1-dimethylethyl) ethanediamide> 9.8 g (0.11 g) was added to a 100 mL glass reactor.
Mol) of 2-amino-2-methylpropanol and 3
0 g of methanol was charged and the solution was stirred at room temperature. Then, 5.9 g (0.05 mol) of dimethyl oxalate was gradually added dropwise to this solution. After the dropping, the solution was stirred at room temperature for 24 hours. Further, 30 g of toluene was added to this solution, and methanol was removed under reduced pressure. The obtained crystals were collected by filtration and dried under reduced pressure to obtain 10.93 g of white crystals.

The white crystals were analyzed by ¹ H-NMR. The results of ¹ H-NMR analysis are shown in Table 2.

[0135]

[Table 2]

From this result, it was confirmed that the obtained white crystals were the title compound.

<Production Example 3: Synthesis of N, N'-bis [2-hydroxy-1,1-bis (hydroxymethyl) ethyl] ethanediamide> In a 200 mL glass reactor, 1
1.5 g (0.10 mol) of trishydroxymethylaminomethane and 90 g of methanol were charged, and this suspension solution was stirred at room temperature. Then, in this suspension solution, 5.
0 g (0.04 mol) of dimethyl oxalate was gradually added dropwise. After the dropping, the solution was stirred at 65 ° C. for 2 hours. The obtained crystals were collected by filtration and dried under reduced pressure to obtain 12.07 g of white crystals.

The white crystals were analyzed by ¹ H-NMR. The results of ¹ H-NMR analysis are shown in Table 3.

[0139]

[Table 3]

From this result, it was confirmed that the obtained white crystals were the title compound.

<Production Example 4: Synthesis of N, N'-bis (2-hydroxyethyl) propanediamide> In a 200 mL glass reactor, 20.0 g (0.33 mol) of aminoethanol, 40 g of toluene and 40 g of methanol was charged and the solution was stirred at room temperature. Then, 20.0 g (0.15 mol) of dimethyl malonate was gradually added dropwise to this solution. After the dropping, the solution was stirred at 70 ° C. for 2 hours. Further, methanol and toluene were distilled off, and 20 g of methanol was added to the residue to dissolve it, and 50 g of toluene was further added. The obtained crystals were collected by filtration and dried under reduced pressure to obtain 26.0 g of white crystals.

The white crystals were analyzed by ¹ H-NMR. The results of ¹ H-NMR analysis are shown in Table 4.

[0143]

[Table 4]

From this result, it was confirmed that the obtained white crystals were the title compound.

<Production Example 5: Synthesis of N, N'-bis (2-hydroxy-1,1-dimethylethyl) propanediamide> In a 200 mL glass reactor, 19.7 g (0.
22 mol) of 2-amino-2-methylpropanol, 3
0 g of toluene and 30 g of methanol were charged, and the solution was stirred at room temperature. Then add 13.2 to this solution.
g (0.10 mol) of dimethyl malonate was gradually added dropwise. After the dropping, the solution was stirred at 65 ° C. for 2 hours. further,
Methanol was distilled off, and the obtained crystals were collected by filtration and dried under reduced pressure to obtain 22.4 g of white crystals.

The white crystals were analyzed by ¹ H-NMR. The results of ¹ H-NMR analysis are shown in Table 5.

[0147]

[Table 5]

From this result, it was confirmed that the obtained white crystals were the title compound.

<Production Example 6: Synthesis of N, N'-bis (2-hydroxyethyl) butanediamide> In a 200 mL glass reactor, 9.2 g (0.15 mol) of aminoethanol, 40 g of methanol and 40 g were added. Of toluene was charged and the solution was stirred at room temperature. Next, 10.0 g (0.07 mol) of dimethyl succinate was gradually added dropwise to this solution. After dropping, methanol was distilled off at 65 ° C,
40 g of toluene was added. After 20 g of isopropyl alcohol was added and the residual methanol was distilled off, the obtained crystals were collected by filtration and dried under reduced pressure to obtain 4.68 g of white crystals.

The white crystals were analyzed by ¹ H-NMR. The results of ¹ H-NMR analysis are shown in Table 6.

[0151]

[Table 6]

From this result, it was confirmed that the obtained white crystals were the title compound.

<Production Example 7: Synthesis of N, N'-bis (2-hydroxyethyl) pentanediamide> In a 200 mL glass reactor, 13.8 g (0.23 mol) of aminoethanol, 8 g of methanol and 5 g of water was charged and the solution was stirred at room temperature. Then add 1 to this solution
6.0 g (0.10 mol) of dimethyl glutarate was gradually added dropwise. After dropping, methanol was distilled off at 65 ° C., and 1
00 g of toluene was added. Further, the residual methanol was distilled off, 20 g of isopropyl alcohol was added, and after cooling, the obtained crystals were collected by filtration and dried under reduced pressure to obtain 13.1
4 g of white crystals were obtained.

The white crystals were analyzed by ¹ H-NMR. The results of ¹ H-NMR analysis are shown in Table 7.

[0155]

[Table 7]

From this result, it was confirmed that the obtained white crystals were the title compound.

<Production Example 8: Synthesis of N, N'-bis (2-hydroxyethyl) hexanediamide> To a 200 mL glass reactor, 8.0 g (0.13 mol) of aminoethanol and 100 g of methanol were added. After charging, this solution was stirred at room temperature. Then 9.3 g (0.0
(5 mol) dimethyl adipate was gradually added dropwise. After dropping, the mixture was stirred at room temperature for 13 hours. 100 g of toluene was added, residual methanol was distilled off at 110 ° C., and after cooling, 12
g of crude product was obtained. This was dissolved in 40 g of isopropyl alcohol by heating and gradually cooled. The obtained crystals were collected by filtration and dried under reduced pressure to obtain 5.7 g of white needle crystals.

The white crystals were analyzed by ¹ H-NMR. The results of ¹ H-NMR analysis are shown in Table 8.

[0159]

[Table 8]

From this result, it was confirmed that the obtained white crystals were the title compound.

<Production Example 9: 2-hydroxy-N, N′-
Synthesis of Bis (2-hydroxyethyl) butanediamide>
In a 1000 mL glass reactor, 145.0 g (2.
(37 mol) aminoethanol, 150 g of methanol, and 10 g of water were charged, and the solution was stirred at room temperature. Then, 195 g (1.03 mol) of diethyl malate was gradually added dropwise to this solution. 2 at room temperature after dropping
Stir for hours. After 100 g of toluene was added and the methanol was distilled off under reduced pressure, 30 g of methanol and 250 g
Of toluene was added, and the obtained crystals were collected by filtration and washed with a mixed solvent of methanol and toluene. It was dried under reduced pressure to obtain 215.0 g of white crystals.

The white crystals were analyzed by ¹ H-NMR. The results of ¹ H-NMR analysis are shown in Table 9.

[0163]

[Table 9]

From this result, it was confirmed that the obtained white crystals were the title compound.

<Production Example 10: 2,3-dihydroxy-
Synthesis of N, N'-bis (2-hydroxyethyl) butanediamide> 1000 mL in a glass reactor, 160.
0 g (2.62 mol) of aminoethanol, 300 g of methanol, and 10 g of water were charged, and the solution was stirred at room temperature. Then 250.0 g (1.
(21 mol) diethyl tartrate was gradually added dropwise. After the dropping, the mixture was stirred at room temperature for 15 hours. After roughly distilling off methanol, 360 g of isopropyl alcohol was added. The obtained crystals were collected by filtration and dried under reduced pressure to obtain 259.7 g of white scaly crystals.

The white crystals were analyzed by ¹ H-NMR. The results of ¹ H-NMR analysis are shown in Table 10.

[0167]

[Table 10]

From this result, it was confirmed that the obtained white crystals were the title compound.

<Production Example 11: Synthesis of N, N′-bis (2-hydroxyethyl) -1,4-benzenedicarboxamide> In a 1000 mL glass reactor, 195.0
g (1.03 mol) of terephthaldimethyl, 400 g of methanol, 100 g of toluene and 15 g of water were charged, and the suspension solution was stirred at 40 ° C. Then, 140.0 g (2.29 mol) of aminoethanol was gradually added dropwise to this suspension solution. After dropping, the mixture was stirred at 68 ° C. for 1 hour. After roughly distilling off methanol, 275 g of toluene was added. The obtained crystals were collected by filtration and dried under reduced pressure to give 191.2 g of white crystals.

The white crystals were analyzed by ¹ H-NMR. The results of ¹ H-NMR analysis are shown in Table 11.

[0171]

[Table 11]

From this result, it was confirmed that the obtained white crystals were the title compound.

<Production Example 12: 4,4 ′, 5,5′-tetrahydro-4,4,4 ′, 4′-tetramethyl-2,
Synthesis of 2'-bisoxazole> In a 50 mL glass reactor, 1.0 g (0.004 mol) of N, N'-bis (2-hydroxy-1,1-dimethylethyl) ethanediamide, 40 g of xylene, 25 g of mesitylene and 0.2 mL of methanesulfonic acid were charged, and the solution was heated under reflux at 140 ° C. for 2 hours under a nitrogen atmosphere. The produced water was removed using a Dean-Stark tube, and the resulting crystals were collected by filtration under cooling to room temperature and dried under reduced pressure to give 0.18
g of white needle crystals were obtained.

The white crystals were analyzed by ¹ H-NMR. The results of ¹ H-NMR analysis are shown in Table 12.

[0175]

[Table 12]

From this result, it was confirmed that the obtained white crystals were the title compound.

<Production Example 13: Synthesis of 2,2 ′-(1,3-propanediyl) bis [4,5-dihydro-4,4-dimethyloxazole]> In a 200 mL glass reactor, 34.6 g was added. (0.39 mol) 2-amino-2-methylpropanol, 60 g xylene and 16.1 g
Of dimethyl glutarate was charged, and this solution was heated under reflux at 133 ° C. for 19 hours in a nitrogen atmosphere. The water produced was removed using a Dean-Stark tube, and the resulting crystals were collected by filtration under cooling to room temperature and dried under reduced pressure to obtain 11.3 g of a crude product. The crude product was purified by column chromatography to obtain 1.36 g of white crystals.

The white crystals were analyzed by ¹ H-NMR. The results of ¹ H-NMR analysis are shown in Table 13.

[0179]

[Table 13]

From this result, it was confirmed that the obtained white crystals were the title compound.

<Production Example 14: Synthesis of 2,2 ′-(1,4-butanediyl) bis [4,5-dihydro-4,4-dimethyloxazole]> In a 200 mL glass reactor, 22.0 g ( 0.25 mol) 2-amino-2-methylpropanol, 50 g xylene and 50 g mesitylene and 0.4 g methanesulfonic acid are charged,
The solution was stirred at room temperature. 14.0g in this solution
Adipic acid (0.10 mol) was added dropwise, and 138-144 was removed using a Dean-Stark tube to remove water produced.
The mixture was heated to reflux at 25 ° C for 25 hours. Under cooling to room temperature, 50 g of water was added and the organic layer was collected. After washing the organic layer with 50 g of water, the organic solvent was distilled off under reduced pressure to obtain 14.0 g of a yellow oily substance.

The yellow oily substance was analyzed by ¹ H-NMR. The results of ¹ H-NMR analysis are shown in Table 14.

[0183]

[Table 14]

From this result, it was confirmed that the obtained yellow oil was the title compound.

<Production Example 15: Synthesis of 2,2 ′-(1,2-ethanediyl) bis [4,5-dihydro-4,4-dimethyloxazole]> In a 300 mL glass reactor, 0.90 g of Zinc chloride, 10.0 g (0.11 mol)
2-amino-2-methylpropanol, 7.0 g
(0.05 mol) malic acid and 100 g of xylene were charged and stirred under a nitrogen atmosphere. The mixture was heated under reflux at 135 ° C. for 20 hours while removing water produced using a Dean-Stark tube. Under cooling to room temperature, 100 g of water and 5
0 g of ethyl acetate was added and the organic layer was collected. After washing the organic layer with 50 g of water, the organic solvent was distilled off under reduced pressure to 2.8 g.
To give a brown solid.

The brown solid was analyzed by ¹ H-NMR. The results of ¹ H-NMR analysis are shown in Table 15.

[0187]

[Table 15]

From this result, it was confirmed that the obtained brown solid was the title compound.

Production Example 16: Production of Internally Crosslinked Hydrophilic Resin> In a 500 mL separable flask, 147.
1 g of acrylic acid (Toa Gosei AA-98), 12
3.2 g of 48.7% aqueous sodium hydroxide solution, 14
5.1 g distilled water and 0.3 g Viscoat # 295
(Trimethylolpropane triacrylate; manufactured by Osaka Organic Chemical Industry Co., Ltd.) was charged and the flask was filled with nitrogen gas. Next, 0.062 g of ammonium persulfate (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.021 g of sodium hydrogen sulfite (manufactured by Nacalai Tesque, Inc.) were charged to this flask as a redox initiator, and the temperature in the flask was 40 ° C.
-80 ° C) and left to stand.

After 6 hours, the gel polymer formed in the flask was separated and dried in a hot air dryer at 150 ° C. overnight. Then, the dried polymer was pulverized with a small pulverizer and then passed through a 50-mesh sieve to obtain an internally crosslinked hydrophilic resin.

Example 1 To 0.5 g of distilled water, 0.05 g of N, N′-bis (2-hydroxyethyl) ethanediamide obtained in Production Example 1 was added to obtain a solution.

This solution was prepared in the same manner as in 10.
The mixture was added dropwise to 0 g of the hydrophilic resin, and the mixture was placed in a small pulverizer and stirred for 1 minute, and then placed in a petri dish. By heating this in a dryer at 175 ° C. for 30 minutes, a surface-crosslinked water absorbent resin was produced.

The surface-crosslinked water-absorbent resin was tested using the following water-absorbency test under pressure test.

(Water absorption test under pressure) Polyethylene terephthalate (PET) having a crucible type glass filter having an inner diameter of 40 mm and an inner diameter slightly smaller than 40 mm
The total weight (W _a ) of the apparatus under pressure consisting of the film-making film was precisely weighed. Then, the film was once removed from the apparatus, approximately 0.5 g of the surface-crosslinked water-absorbent resin was uniformly placed on the bottom surface of the glass filter, and the film was gently placed again on the water-absorbent resin. Total weight (W
_G1 ) was precisely weighed. The difference in total weight (W _G1 −W _a ) was taken as the weight (W _P ) of the surface-crosslinked water-absorbent resin contained in the apparatus.

It is arranged on the surface-crosslinked water absorbent resin.
20 g / cm through the film ^TwoIs adjusted to the load of
Also, a weight having an outer diameter slightly smaller than 40 mm
(Total weight 251g; this weight is the glass fill inside the device.
Without forming a gap with the inner wall of the
The movement is not disturbed). Next
Then, the bottom of the glass filter is fully immersed in the device itself.
So that it was immersed in a 0.9% NaCl aqueous solution.

After 30 minutes, the apparatus was taken out of the aqueous NaCl solution, the water around the outer periphery of the apparatus was wiped off, and the weight was removed from the apparatus. The weight of the device at this time ( _WG2 ; weight after absorbing water) was precisely weighed.

On the other hand, the weight of the device alone (W _GB1 ) was precisely weighed without disposing the water-absorbing resin in the glass filter, and then the weight of the device (W _GB1 ) after immersion in the aqueous NaCl solution was carried out in the same manner as above. _GB2 ) was used as a blank and precisely weighed.

From the above, the water absorption capacity of the surface-crosslinked water absorbent resin was calculated by the following formula:

[0199]

[Equation 1]

Table 16 shows the water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this example.

Example 2 Instead of N, N′-bis (2-hydroxyethyl) ethanediamide as a cross-linking agent,
0.05 g of N, N'-bis (2-
A surface-crosslinked water-absorbent resin was produced in the same manner as in Example 1 except that hydroxy-1,1-dimethylethyl) ethanediamide was used.

Table 16 shows the water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this example.

Example 3 Instead of N, N′-bis (2-hydroxyethyl) ethanediamide as a cross-linking agent,
0.05 g of N, N'-bis [2- obtained in Production Example 3
A surface-crosslinked water absorbent resin was produced in the same manner as in Example 1 except that hydroxy-1,1-bis (hydroxymethyl) ethyl] ethanediamide was used.

Table 16 shows the water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this example.

Example 4 Instead of N, N′-bis (2-hydroxyethyl) ethanediamide as a cross-linking agent,
0.05 g of N, N'-bis (2-
A surface-crosslinked water absorbent resin was produced in the same manner as in Example 1 except that hydroxyethyl) propanediamide was used.

Table 16 shows the water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this example.

Example 5 Instead of N, N′-bis (2-hydroxyethyl) ethanediamide as a cross-linking agent,
0.05 g of N, N'-bis (2-
A surface-crosslinked water absorbent resin was produced in the same manner as in Example 1 except that hydroxy-1,1-dimethylethyl) propanediamide was used.

Table 16 shows the water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this example.

Example 6 Instead of N, N′-bis (2-hydroxyethyl) ethanediamide as a cross-linking agent,
0.05 g of N, N'-bis (2-
A surface-crosslinked water absorbent resin was produced in the same manner as in Example 1 except that hydroxyethyl) butanediamide was used.

The water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this example is shown in Table 16.

Example 7 Instead of N, N′-bis (2-hydroxyethyl) ethanediamide as a cross-linking agent,
0.05 g of N, N'-bis (2-
A surface-crosslinked water absorbent resin was produced in the same manner as in Example 1 except that hydroxyethyl) pentanediamide was used.

Table 16 shows the water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this example.

Example 8 Instead of N, N′-bis (2-hydroxyethyl) ethanediamide as a cross-linking agent,
0.05 g of N, N'-bis (2-
A surface-crosslinked water absorbent resin was produced in the same manner as in Example 1 except that hydroxyethyl) hexanediamide was used.

Table 16 shows the water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this example.

Example 9 Instead of N, N′-bis (2-hydroxyethyl) ethanediamide as a cross-linking agent,
0.05 g of 2-hydroxy-N, obtained in Preparation Example 9,
A surface-crosslinked water-absorbent resin was produced in the same manner as in Example 1 except that N'-bis (2-hydroxyethyl) butanediamide was used.

Table 16 shows the water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this example.

Example 10 Instead of N, N′-bis (2-hydroxyethyl) ethanediamide as a cross-linking agent, 0.05 g of 2,3-dihydroxy-N, N′-obtained in Production Example 10 was used. A surface-crosslinked water absorbent resin was produced in the same manner as in Example 1 except that bis (2-hydroxyethyl) butanediamide was used.

Table 16 shows the water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this example.

Example 11 Instead of N, N′-bis (2-hydroxyethyl) ethanediamide as a cross-linking agent, 0.05 g of N, N′-bis (2-hydroxyethyl) obtained in Production Example 11 was used. ) -1,4-benzenedicarboxamide was used to produce a surface-crosslinked water absorbent resin in the same manner as in Example 1.

The water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this example is shown in Table 16.

Example 12 Instead of N, N′-bis (2-hydroxyethyl) ethanediamide as a cross-linking agent, 0.05 g of 4,4 ′, 5 obtained in Production Example 12 was used.
Other than using 5'-tetrahydro-4,4,4 ', 4'-tetramethyl-2,2'-bisoxazole,
A surface-crosslinked water-absorbent resin was produced in the same manner as in Example 1.

Table 16 shows the water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this example.

Example 13 Instead of N, N′-bis (2-hydroxyethyl) ethanediamide as a cross-linking agent, 0.05 g of 2,2′-obtained in Production Example 13 was used.
(1,3-propanediyl) bis [4,5-dihydro-
4,4-dimethyloxazole]
A surface-crosslinked water-absorbent resin was produced in the same manner as in Example 1.

Table 16 shows the water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this example.

Example 14 Instead of N, N′-bis (2-hydroxyethyl) ethanediamide as a cross-linking agent, 0.05 g of 2,2′-obtained in Production Example 14 was used.
(1,4-butanediyl) bis [4,5-dihydro-
4,4-dimethyloxazole]
A surface-crosslinked water-absorbent resin was produced in the same manner as in Example 1.

Table 16 shows the water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this example.

Example 15 Instead of N, N′-bis (2-hydroxyethyl) ethanediamide as a cross-linking agent, 0.05 g of 2,2′-obtained in Production Example 15 was used.
(1,2-ethanediyl) bis [4,5-dihydro-
4,4-dimethyloxazole]
A surface-crosslinked water-absorbent resin was produced in the same manner as in Example 1.

Table 16 shows the water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this example.

<Comparative Example 1> As a cross-linking agent, 0.05 was used instead of N, N'-bis [2-hydroxyethyl-1,1-bis (hydroxymethyl) ethyl] propanediamide.
A surface-crosslinked water absorbent resin was produced in the same manner as in Example 1 except that g of diethylene glycol was used.

Table 16 shows the water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this comparative example.

<Comparative Example 2> As a cross-linking agent, 0.05 was used instead of N, N'-bis [2-hydroxyethyl-1,1-bis (hydroxymethyl) ethyl] propanediamide.
A surface-crosslinked water-absorbent resin was produced in the same manner as in Example 1 except that g of ethylene glycol diglycidyl ether was used.

Table 16 shows the water absorption capacity of the surface-crosslinked water-absorbent resin obtained in this comparative example.

[0233]

[Table 16]

As shown in Table 16, a water-absorbent resin surface-crosslinked using the crosslinking agent of the present invention (Examples 1 to 1)
It is understood that all of 5) have a high water absorption capacity.
In addition, these water-absorbent resins have excellent water-absorbing property as compared with the surface-crosslinked resin using a conventional alcohol-based crosslinking agent (Comparative Example 1). Furthermore, the water-absorbent resins produced in Examples 1 to 15 are significantly superior to those surface-crosslinked using a conventional crosslinking agent having an epoxy group, which may cause skin irritation. It can be seen that there is no significant difference in water absorption.

[0235]

According to the present invention, it is possible to obtain a cross-linking agent for a water-absorbent resin which is superior to the conventional alcohol-based cross-linking agent and which can provide water absorption almost equal to that of the conventional cross-linking agent having an epoxy group. it can. Since the cross-linking agent for a water-absorbent resin of the present invention does not contain an epoxy group in its structure, at the time of manufacturing a water-absorbent resin and when mounting a sanitary article such as an incontinence pad using the resin as a water-absorbing agent. Problems such as skin irritation can be avoided.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nobuaki Aoki             236 Nakai, Tatsuno-cho, Tatsuno-shi, Hyogo Nagase             Within Chemtex Co., Ltd. (72) Inventor Tetsuya Hosomi             236 Nakai, Tatsuno-cho, Tatsuno-shi, Hyogo Nagase             Within Chemtex Co., Ltd. F term (reference) 4J002 BG011 CF181 CL011 CL021                       CM041 EP026 EU226 FD146

Claims (27)

[Claims] 1. A compound represented by the following general formula (I), which is a cross-linking agent: Here, n is an integer of 2 to 6; R ₁ is a linear, branched, or cyclic n-valent carbon atom having 1 to 20 carbon atoms, which may be substituted with a hydroxyl group. A hydrogen group; and R ₂ to R ₅ are each independently-
H, —CH ₃ or —CH ₂ OH;
Cross-linking agent. 2. The hydrocarbon group is an aromatic hydrocarbon group,
The crosslinking agent according to claim 1, which is a group selected from the group consisting of an aliphatic hydrocarbon group and an alicyclic hydrocarbon group. 3. In the compound represented by the general formula (I), n is an integer of 2 to 4, and R ₁ is an n-valent group which may be substituted with a hydroxyl group having 6 carbon atoms. The cross-linking agent according to claim 1, containing a compound which is the aromatic hydrocarbon group of. 4. Among the compounds represented by the general formula (I), n is an integer of 2 to 6 and R ₁ is 1 to 2
The crosslinking agent according to claim 1, containing a compound which is an n-valent aliphatic hydrocarbon group which may be substituted with a hydroxyl group having 0 carbon atoms. 5. R _{1 of the} compound is —CH ₂ —, —C
_{H 2 CH 2 -, - CH} 2 CH 2 CH 2 -, - CH 2 CH
_{2 CH 2 CH 2 -, -} CH (OH) CH 2 -, - CH
(OH) CH (OH)-, The cross-linking agent according to claim 1, which is a group selected from the group consisting of: 6. The compound is N, N′-bis (2-hydroxyethyl) ethanediamide, N, N′-bis (2
-Hydroxy-1,1-dimethylethyl) ethanediamide, N, N'-bis [2-hydroxy-1,1-bis (hydroxymethyl) ethyl] ethanediamide, N,
N'-bis (2-hydroxyethyl) propanediamide, N, N'-bis (2-hydroxy-1,1-dimethylethyl) propanediamide, N, N'-bis (2-hydroxyethyl) butanediamide, N, N'-bis (2
-Hydroxyethyl) pentanediamide, N, N'-bis (2-hydroxyethyl) hexanediamide, 2-hydroxy-N, N'-bis (2-hydroxyethyl) butanediamide, 2,3-dihydroxy-N, N ' -Bis (2-hydroxyethyl) butanediamide, and N,
The crosslinking agent according to claim 1, containing at least one selected from the group consisting of N′-bis (2-hydroxyethyl) -1,4-benzenedicarboxamide. 7. A cross-linking agent having the following general formula (I ′):
Compound represented by: Wherein R ₂ to R ₅ and R _{2 ′} to R _{5 ′} are each independently —H, —CH ₃ or —CH ₂ OH; 8. A cross-linking agent having the following general formula (II):
Compound represented by: Here, n is an integer of 2 to 6; R ₁ is a linear, branched, or cyclic n-valent carbon atom having 1 to 20 carbon atoms, which may be substituted with a hydroxyl group. A hydrogen group; and R ₆ to R ₉ are each independently-
H, —CH ₃ or —CH ₂ OH;
Cross-linking agent. 9. The hydrocarbon group is an aromatic hydrocarbon group,
The crosslinking agent according to claim 8, which is a group selected from the group consisting of an aliphatic hydrocarbon group and an alicyclic hydrocarbon group. 10. In the compound represented by the general formula (II), n is an integer of 2 to 4 and R ₁ has 6 carbon atoms and may be substituted with a hydroxyl group. 9. The cross-linking agent according to claim 8, which contains a compound that is a valent aromatic hydrocarbon group. 11. The compound represented by the general formula (II), wherein n is an integer of 2 to 6 and R ₁ is substituted with a hydroxyl group having 1 to 20 carbon atoms. The cross-linking agent according to claim 8, which contains a compound that is a good n-valent aliphatic hydrocarbon group. 12. R _{1 of the} compound is —CH ₂ —, —
_{CH 2 CH 2 -, - CH} 2 CH 2 CH 2 -, - CH 2 C
_{H 2 CH 2 CH 2 -,} - CH (OH) CH 2 -, - CH
(OH) CH (OH)-, The cross-linking agent according to claim 8, which is a group selected from the group consisting of: 13. The compound is 4,4 ′, 5,5′-
Tetrahydro-4,4,4 ', 4'-tetramethyl-
2,2′-bisoxazole, 2,2 ′-(1,3-propanediyl) bis [4,5-dihydro-4,4-dimethyloxazole], 2,2 ′-(1,4-butanediyl) bis [4,5-Dihydro-4,4-dimethyloxazole], and 2,2 '-(1,2-ethanediyl)
At least one selected from the group consisting of bis [4,5-dihydro-4,4-dimethyloxazole],
The cross-linking agent according to claim 8. 14. A water-absorbent resin obtained by cross-linking a hydrophilic resin, wherein the cross-link is represented by the following general formula (III): embedded image (Here, n is an integer of 2 to 6; R ₁ is a linear, branched, or cyclic n-valent group having 1 to 20 carbon atoms, which may be substituted with a hydroxyl group. A hydrocarbon group; and R ₂ to R ₅ are each independently-
H, —CH ₃ or —CH ₂ OH). 15. The cross-linking agent according to claim 14, wherein the hydrocarbon group is a group selected from the group consisting of an aromatic hydrocarbon group, an aliphatic hydrocarbon group, and an alicyclic hydrocarbon group. 16. The bridge is an n-valent aromatic hydrocarbon group optionally substituted with a hydroxyl group, wherein n is an integer of 2 to 4 and R ₁ has 6 carbon atoms, The water absorbent resin according to claim 14, which has a structure. 17. The crosslink is an n-valent aliphatic hydrocarbon group in which n is an integer of 2 to 6 and R ₁ is optionally substituted with a hydroxyl group having 1 to 20 carbon atoms. 15. The water absorbent resin according to claim 14, which has a structure. 18. R ₁ is —CH ₂ —, —CH ₂ CH _{2
-, - CH 2 CH 2 CH} 2 -, - CH 2 CH 2 CH 2 C
_{H 2 -, - CH (OH} ) CH 2 -, - CH (OH) CH
(OH)-, The water absorbent resin according to claim 14, which is a group selected from the group consisting of: 19. The hydrophilic resin is modified polyacrylic acid and its derivative, modified polylactic acid and its derivative,
The water absorbent resin according to any one of claims 14 to 18, which is at least one resin selected from the group consisting of modified polyglutamic acid and its derivatives, and modified polyaspartic acid and its derivatives. 20. A water-absorbent resin obtained by cross-linking a hydrophilic resin, wherein the cross-link is represented by the following general formula (III ′): (Where R ₂ to R ₅ and R _{2 ′} to R _{5 ′} are
Each independently, -H, -CH ₃ or _-CH 2 OH
Is a water-absorbent resin. 21. The hydrophilic resin is modified polyacrylic acid and its derivative, modified polylactic acid and its derivative,
The water absorbent resin according to claim 20, which is at least one resin selected from the group consisting of modified polyglutamic acid and its derivatives, and modified polyaspartic acid and its derivatives. 22. A water-absorbent resin obtained by cross-linking a hydrophilic resin with the cross-linking agent according to claim 1. 23. A water absorbent resin obtained by crosslinking a hydrophilic resin with the crosslinking agent according to claim 7. 24. A water-absorbent resin obtained by cross-linking a hydrophilic resin with the cross-linking agent according to claim 8. 25. A method for producing a water-absorbent resin, which comprises a step of mixing a hydrophilic resin and the crosslinking agent according to any one of claims 1 to 6; and a step of heating the mixture. A method of including. 26. A method for producing a water absorbent resin, comprising the steps of mixing a hydrophilic resin and the crosslinking agent according to claim 7; and heating the mixture.
Method. 27. A method for producing a water-absorbent resin, comprising a step of mixing a hydrophilic resin and the crosslinking agent according to any one of claims 8 to 13; and a step of heating the mixture. A method of including.