JP7153447B2 - Hydrophilic composition and hydrophilic sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hydrophilic composition containing a zwitterionic polymer and a specific water-based polyester resin, and a hydrophilic sheet having a hydrophilic layer formed using this hydrophilic composition.

Conventionally, zwitterionic polymers (polymers having repeating units derived from zwitterionic monomers) and hydrophilic coating agents containing zwitterionic polymers have been known.
For example, Patent Document 1 discloses a hydrophilic coating agent containing an alkoxysilyl group-containing polymer obtained by polymerizing a monomer component containing a betaine monomer and an alkoxysilyl group-containing compound, and a hydrophilic coating agent formed using this hydrophilic coating agent. An anti-fogging sheet having a coated film and the like are described.

WO2014/084219

A laminated sheet having a hydrophilic layer containing a zwitterionic polymer on a substrate layer is useful as a hydrophilic sheet such as an antifogging sheet, as described in Patent Document 1.
However, according to the studies of the present inventors, it has been found that in such a hydrophilic sheet, the blocking resistance tends to decrease as the hydrophilicity increases. For this reason, after manufacturing a hydrophilic sheet with excellent hydrophilicity, if it is wound into a roll and stored, or if it is cut and stacked and stored, there is a possibility that problems will occur during use. .
Accordingly, there has been a demand for a hydrophilic sheet having a hydrophilic layer containing a zwitterionic polymer, which is excellent in both hydrophilicity and blocking resistance.

The present invention has been made in view of the above circumstances, and provides a hydrophilic sheet having a hydrophilic layer containing a zwitterionic polymer, the hydrophilic sheet being excellent in both hydrophilicity and blocking resistance; An object of the present invention is to provide a hydrophilic composition suitable for use as a material for forming a hydrophilic layer of a hydrophilic sheet having such properties.

As a result of intensive studies to solve the above problems, the present inventors have found that a hydrophilic layer is formed using a hydrophilic composition containing a zwitterionic polymer and a specific water-based polyester resin in a specific ratio. found that a hydrophilic sheet excellent in both hydrophilicity and anti-blocking property can be efficiently produced, and completed the present invention.

Thus, according to the present invention, the following hydrophilic compositions [1] to [7] and hydrophilic sheet [8] are provided.
[1] A hydrophilic composition containing the following components (A) and (B), wherein the content of component (B) is 60 to 152 parts by mass per 100 parts by mass of component (A) A hydrophilic composition.
(A) component: zwitterionic polymer (B) component: water-based polyester resin having a glass transition temperature (Tg) of 50° C. or higher [2] The zwitterionic polymer of component (A) is represented by the following formula (1) The hydrophilic composition according to [1], which is a polymer having the repeating unit shown.

[In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² and R ³ each independently represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms with or without an ether bond, or an ether bond or without a cyanoalkyl group having 2 to 11 carbon atoms, an alkenyl group having 2 to 10 carbon atoms with or without an ether bond, or an aryl group having 6 to 20 carbon atoms with or without a substituent. Also, R ² and R ³ may combine with each other to form a ring. A ¹ is represented by the following formulas (2) to (4)

(wherein A ² and A ³ each independently represent an alkylene group having 1 to 10 carbon atoms with or without a substituent; R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom; represents an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 20 carbon atoms with or without a substituent, n represents an integer of 1 to 10. *1 represents a bond with a carbon atom. , *2 represents a bond with a nitrogen atom.)
represents a divalent group represented by any one of —G ^— represents a deprotonated carboxy group (—COO ⁻ ) or a deprotonated sulfo group (—SO ₃ ⁻ ). m represents an integer of 2 to 5; ]
[3] The hydrophilic composition according to [2], wherein -G ^- in the formula (1) is a deprotonated sulfo group.
[4] The zwitterionic polymer of component (A) has a repeating unit derived from a zwitterionic monomer, and a repeating unit having a carboxy group, a sulfo group, or a group formed by reacting these groups with a base ( However, the hydrophilic composition according to any one of [1] to [3], which is a polymer having a repeating unit derived from a zwitterionic monomer.
[5] The water-based polyester resin of the component (B) is represented by the following formula (5)

(In the formula, Ar represents a trivalent aromatic group, X represents a hydrophilic group, and Y represents an alkylene group or an arylene group.)
The hydrophilic composition according to any one of [1] to [4], which is a polymer having a repeating unit represented by:
[6] The description of [5], wherein the hydrophilic group represented by X is —SO ₃ H, —CO ₂ H, —PO ₃ H ₂ , or a group formed by reacting these groups with a base. Hydrophilic composition.
[7] The hydrophilic composition according to any one of [1] to [6], further comprising the following component (C).
Component (C): an ionic compound having a cation having 0 to 10 carbon atoms [8] A hydrophilic sheet obtained by laminating a hydrophilic layer directly or via another layer on a base sheet, and a hydrophilic sheet, wherein the hydrophilic layer is formed using the hydrophilic composition according to any one of [1] to [7].

According to the present invention, there are provided a hydrophilic sheet having a hydrophilic layer containing a zwitterionic polymer, which is excellent in both hydrophilicity and blocking resistance, and a hydrophilic sheet having such properties. Provided is a hydrophilic composition suitably used as a material for forming the hydrophilic layer of .

Hereinafter, the present invention will be described in detail by dividing it into 1) hydrophilic composition and 2) hydrophilic sheet.

1) Hydrophilic composition The hydrophilic composition of the present invention is a hydrophilic composition containing the following components (A) and (B), wherein the content of component (B) is equal to component (A) It is characterized by being 60 to 152 parts by mass with respect to 100 parts by mass.
(A) component: zwitterionic polymer (B) component: water-based polyester resin having a glass transition temperature (Tg) of 50°C or higher

[(A) component: zwitterionic polymer]
The hydrophilic composition of the present invention contains a zwitterionic polymer as component (A).
Since the hydrophilic composition of the present invention contains a zwitterionic polymer, it is possible to efficiently form a hydrophilic layer with extremely excellent hydrophilicity by using this hydrophilic composition.
A zwitterionic polymer is a polymer having repeating units derived from a zwitterionic monomer.
A zwitterionic monomer refers to a compound having a polymerizable carbon-carbon double bond, a cationic portion, and an anionic portion in the molecule.

Although the weight average molecular weight of the zwitterionic polymer is not particularly limited, it is usually 50,000 to 3,000,000, preferably 100,000 to 2,500,000, and more preferably 200,000 to 2,000,000.
The weight average molecular weight of the zwitterionic polymer can be measured according to the method described in the Examples.

Examples of repeating units derived from zwitterionic monomers include those represented by the following formula (1).

In formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² and R ³ each independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms with or without an ether bond, an ether bond A cyanoalkyl group having 2 to 11 carbon atoms with or without, an alkenyl group having 2 to 10 carbon atoms with or without an ether bond, or an aryl group having 6 to 20 carbon atoms with or without a substituent . Also, R ² and R ³ may combine with each other to form a ring.

The number of carbon atoms in the alkyl group having 1 to 10 carbon atoms with or without an ether bond for R ² and R ³ is preferably 1 to 8, more preferably 1 to 5.
The alkyl group having no ether bond includes methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group and the like.
Examples of the alkyl group having an ether bond include groups represented by the following formulas (6) and (7).

In formula (6), R ⁷ represents an alkyl group having 1 to 8 carbon atoms, Z ¹ represents an alkylene group having 2 to 9 carbon atoms, and the total number of carbon atoms of R ⁷ and Z ¹ is 3 to 10. * represents a bond.
In formula (7), R ⁸ represents an alkyl group having 1 to 6 carbon atoms, Z ² represents an alkylene group having 2 to 7 carbon atoms, and Z ³ represents an alkylene group having 2 to 7 carbon atoms. , R ⁸ , Z ² and Z ³ have 5 to 10 carbon atoms in total. * represents a bond.

The number of carbon atoms in the cyanoalkyl group having 2 to 11 carbon atoms with or without an ether bond for R ² and R ³ is preferably 2 to 9, more preferably 2 to 6. .
The cyanoalkyl group having no ether bond includes cyanomethyl group, 2-cyanoethyl group, 3-cyanopropyl group, 4-cyanobutyl group, 6-cyanohexyl group and the like.
Examples of the cyanoalkyl group having an ether bond include groups represented by the following formulas (8) and (9).

In formula (8), R ⁹ represents a cyanoalkyl group having 2 to 9 carbon atoms, Z ⁴ represents an alkylene group having 2 to 9 carbon atoms, and the total number of carbon atoms of R ⁹ and Z ⁴ is 4. ~11. * represents a bond.
In formula (9), R ¹⁰ represents a cyanoalkyl group having 2 to 7 carbon atoms, Z ⁵ represents an alkylene group having 2 to 7 carbon atoms, and Z ⁶ represents an alkylene group having 2 to 7 carbon atoms. and the total number of carbon atoms of R ¹⁰ , Z ⁵ and Z ⁶ is 6-11. * represents a bond.

The carbon number of the alkenyl group having 2 to 10 carbon atoms with or without an ether bond in R ² and R ³ is preferably 2 to 9, more preferably 2 to 6.
Examples of alkenyl groups having no ether bond include vinyl groups, allyl groups, 1-butenyl groups, 2-butenyl groups, 1-pentenyl groups and the like.
Examples of the alkenyl group having an ether bond include groups represented by the following formula (10) or (11).

In formula (10), R ¹¹ represents an alkenyl group having 2 to 8 carbon atoms, Z ⁷ represents an alkylene group having 2 to 8 carbon atoms, and the total number of carbon atoms of R ¹¹ and Z ⁷ is 4 to 10. * represents a bond.
In formula (11), R ¹² represents an alkenyl group having 2 to 6 carbon atoms, Z ⁸ represents an alkylene group having 2 to 6 carbon atoms, and Z ⁹ represents an alkylene group having 2 to 6 carbon atoms. , R ¹² , Z ⁸ and Z ⁹ have 6 to 10 carbon atoms in total. * represents a bond.

The aryl group having 6 to 20 carbon atoms with or without a substituent for R ² and R ³ preferably has 6 to 10 carbon atoms.
The unsubstituted aryl group includes phenyl group, 1-naphthyl group, 2-naphthyl group and the like.
Examples of substituents of the aryl group having a substituent include alkyl groups having 1 to 6 carbon atoms such as methyl group and ethyl group; alkoxy groups having 1 to 6 carbon atoms such as methoxy group and ethoxy group; fluorine atom, chlorine atom and the like. Halogen atom; and the like.

Examples of the ring formed by combining R ² and R ³ include pyrrolidine ring, piperidine ring, morpholine ring and the like.

In formula (1), A ¹ represents a divalent group represented by any one of formulas (2) to (4) below.

In formulas (2) to (4), A ² and A ³ each independently represent an alkylene group having 1 to 10 carbon atoms with or without a substituent, and R ⁴ , R ⁵ and R ⁶ each represent Each independently represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 20 carbon atoms with or without a substituent. n represents an integer of 1-10. *1 represents a bond with a carbon atom, and *2 represents a bond with a nitrogen atom.

The number of carbon atoms in the alkylene group having 1 to 10 carbon atoms with or without a substituent of A ² and A ³ is preferably 1 to 8, more preferably 1 to 6.
Examples of unsubstituted alkylene groups include linear alkylene groups such as methylene group, ethylene group, trimethylene group, tetramethylene group and pentamethylene group; propane-1,2-diyl group, butane-1,3-diyl group and the like. branched chain alkylene group.
Examples of the substituent of the alkylene group having a substituent include an alkoxy group having 1 to 6 carbon atoms such as a methoxy group and an ethoxy group; a halogen atom such as a fluorine atom and a chlorine atom; and the like.

Examples of alkyl groups having 1 to 6 carbon atoms for R ⁴ , R ⁵ and R ⁶ include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, t-butyl group, n -pentyl group, n-hexyl group and the like.
The aryl group having 6 to 20 carbon atoms with or without a substituent for R ⁴ , R ⁵ and R ⁶ preferably has 6 to 10 carbon atoms.
The unsubstituted aryl group includes phenyl group, 1-naphthyl group, 2-naphthyl group and the like.
Examples of substituents of the aryl group having a substituent include alkyl groups having 1 to 6 carbon atoms such as methyl group and ethyl group; alkoxy groups having 1 to 6 carbon atoms such as methoxy group and ethoxy group; fluorine atom, chlorine atom and the like. Halogen atom; and the like.
n is an integer of 1-10, preferably an integer of 1-5.

In formula (1), —G ^— represents a deprotonated carboxy group (—COO ⁻ ) or a deprotonated sulfo group (—SO ₃ ⁻ ). Among these, when the hydrophilic composition of the present invention is industrially produced ^, -G- is preferably a deprotonated sulfo group. As will be described later, zwitterionic polymers with deprotonated sulfo groups are relatively easy to synthesize and are therefore more suitable for mass production.
In formula (1), m is an integer of 2 to 5, preferably 3 or 4.

In the present invention, the zwitterionic monomer to be used can be appropriately determined according to the target zwitterionic polymer. For example, a zwitterionic polymer having repeating units represented by formula (1) above can be synthesized using a zwitterionic monomer represented by formula (1a) below.

In formula (1a), R ¹ , R ² , R ³ , A ¹ and m each have the same meaning as above.

The method for synthesizing the zwitterionic monomer represented by formula (1a) is not particularly limited.
In the formula (1a), compounds in which "-G-" is a deprotonated carboxyl group include, for example, the corresponding amine compound [formula (1b) below] ^and the formula: hal-(CH ₂ ) _m -COOH(hal represents a halogen atom, and m represents the same meaning as above.) can be obtained by a known method for producing a carboxybetaine compound, such as a method of reacting a halogenated carboxylic acid represented by (JP-A-8-99945 JP-A-7-278071, JP-A-2006-143634, JP-A-2006-143635, etc.).
In addition, in the compound of formula (1a), "-G ^- " is a deprotonated sulfo group, for example, as shown in the following formula, the corresponding amine compound (1b) and sultone compound (1c) are reacted. can be obtained by

In the above formula, R ¹ to R ³ and A ¹ have the same meaning as above, and p is (m-2).
Amine compound (1b) can be produced and obtained by a known method.

Examples of the sultone compound (1c) include 1,2-ethanesultone, 1,3-propanesultone, 1,4-butanesultone, 2,4-butanesultone and 1,5-pentanesultone.
These are known compounds and can be produced and obtained by known methods. Moreover, in the present invention, commercial products can also be used as these sultone compounds.

In the reaction between the amine compound (1b) and the sultone compound (1c), the amount of the sultone compound (1c) used is preferably 0.8 to 1.2 equivalents, more preferably 0 equivalents, relative to the amine compound (1b). .9 to 1.1 equivalents. By setting the amount of the sultone compound (1c) to be within the above range, the step of removing unreacted substances can be omitted or the time required for removal can be shortened.

The reaction between the amine compound (1b) and the sultone compound (1c) may be carried out without solvent or in the presence of an inert solvent.
Ether solvents such as tetrahydrofuran and diglyme; Nitrile solvents such as acetonitrile and propionitrile; Ketone solvents such as acetone and methyl ethyl ketone; Aromatic hydrocarbon solvents such as toluene and xylene; halogenated hydrocarbon solvents such as chloroform; and the like.
When an inert solvent is used, the amount used is not particularly limited, but it is usually 1 to 100 parts by weight per 1 part by weight of the amine compound (1b).

Although the reaction temperature is not particularly limited, it is usually in the range of 0 to 200°C, preferably 10 to 100°C, more preferably 20 to 60°C. In addition, the reaction may be carried out under normal pressure (atmospheric pressure) or under pressurized conditions.
Although the reaction time is not particularly limited, it is usually 12 to 332 hours, preferably 24 to 168 hours.
The reaction is preferably carried out in an atmosphere of an inert gas such as nitrogen gas or argon gas, from the viewpoint of preventing yield reduction due to oxidation by oxygen and hydrolysis of the sultone compound (1c) by moisture in the air.
The progress of the reaction can be confirmed by ordinary analytical means such as gas chromatography, high performance liquid chromatography, thin layer chromatography, NMR and IR.

After completion of the reaction, a post-treatment operation common in synthetic organic chemistry is performed, and if desired, purification is performed by a known purification method such as recrystallization or column chromatography to isolate the desired zwitterionic monomer. .
Moreover, in the present invention, a commercially available product can also be used as the zwitterionic monomer.

The zwitterionic polymer may be a copolymer having repeating units derived from monomers copolymerizable with zwitterionic monomers.

Examples of repeating units derived from monomers copolymerizable with zwitterionic monomers in the zwitterionic polymer include repeating units derived from (meth)acrylic acid, repeating units derived from maleic acid, repeating units derived from crotonic acid, and repeating units derived from itaconic acid. repeating units having a carboxy group such as repeating units derived from; repeating units having a sulfo group such as repeating units derived from (meth)acrylamido t-butylsulfonic acid; methyl (meth)acrylate, ethyl methacrylate (meth) ) a repeating unit derived from an acrylate ester; a repeating unit derived from a (meth)acrylamide; and the like. Here, (meth)acrylic acid means acrylic acid or methacrylic acid (same below).

Among these, the repeating unit derived from the monomer copolymerizable with the zwitterionic monomer preferably has a carboxy group, a sulfo group, or a group obtained by reacting these groups with a base. The presence of these repeating units in the zwitterionic polymer tends to further improve the storage stability of the hydrophilic composition.

The amount of repeating units derived from the zwitterionic monomer in the zwitterionic polymer is usually 50 to 100 mol%, preferably 60 to 99 mol%, more preferably 70 to 95 mol, based on the whole zwitterionic polymer. %.
When the zwitterionic polymer has repeating units having a carboxy group, a sulfo group, or a group formed by reacting these groups with a base, the amount of these repeating units is, based on the whole zwitterionic polymer, It is usually 0 to 50 mol %, preferably 1 to 40 mol %, more preferably 5 to 30 mol %.

The method for synthesizing the zwitterionic polymer is not particularly limited. For example, a zwitterionic polymer can be synthesized by polymerizing a zwitterionic monomer or the like in the presence of a radical polymerization initiator.

Examples of radical polymerization initiators include organic peroxides and azo compounds.
Examples of organic peroxides include diacyl peroxides such as lauroyl peroxide and benzoyl peroxide; 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-butylperoxy)3,3 , 5-trimethylcyclohexane and other peroxyketals; diisopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate and other peroxydicarbonates; t-butyl peroxy-2-ethylhexanoate, t- Examples include peroxyesters such as butyl peroxyisobutyrate.
Azo compounds include 2,2′-azobisisobutyronitrile, 2,2′-azobis(2-methylbutyronitrile), 1,1′-azobis(cyclohexane 1-carbonitrile), 2,2 '-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis(2-methylpropionate), 2 , 2'-azobis (N-butyl-2-methylpropionamide), dimethyl 1,1'-azobis (1-cyclohexanecarboxylate) and other oil-soluble azo polymerization initiators; 4,4'-azobis (4-cyano valeric acid), 2,2′-azobis(2-hydroxymethylpropionitrile), 2,2′-azobis[2-(2-imidazolin-2-yl)propane], 2,2′-azobis(2 ,4-dimethyl-4-methoxyvaleronitrile), 2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride, 2,2′-azobis[2-(2-imidazoline- 2-yl)propane]disulfonate dihydrate, 2,2′-azobis(2-methylpropionamidine) dihydrochloride, 2,2′-azobis[N-(2-carboxyethyl)-2-methylpropionamidine ] tetrahydrate, water-soluble azo polymerization initiators such as 2,2'-azobis [2-methyl-N-(2-hydroxyethyl) propionamide]; and the like, water-soluble azo polymerization initiators are preferred , 4,4′-azobis(4-cyanovaleric acid) is particularly preferred.
These can be used individually by 1 type or in combination of 2 or more types.

The amount of the radical polymerization initiator to be used is generally 0.0001 to 0.1000 mol, preferably 0.0005 to 0.0050 mol, per 1 mol of the monomer used in the polymerization reaction.
The reaction conditions for the radical polymerization reaction are not particularly limited as long as the intended polymerization reaction proceeds. The heating temperature is usually 40 to 150° C., and the reaction time can be appropriately set within the range of 1 minute to 24 hours.
The obtained reaction solution may be used as it is for the preparation of the hydrophilic composition, or the zwitterionic polymer may be isolated and purified by a conventional method and used.

In the present invention, zwitterionic polymers can be used singly or in combination of two or more.

[Component (B): Water-based polyester resin having a glass transition temperature (Tg) of 50°C or higher]
The hydrophilic composition of the present invention contains, as component (B), an aqueous polyester resin having a glass transition temperature (Tg) of 50°C or higher (hereinafter sometimes referred to as "aqueous polyester resin (α)"). do.
Since the hydrophilic composition of the present invention contains the water-based polyester resin (α), a hydrophilic sheet having excellent blocking resistance can be produced by using this hydrophilic composition.

The aqueous polyester resin (α) contained in the hydrophilic resin composition of the present invention is water or a water-soluble organic solvent (e.g., an aqueous solution containing less than 50% by mass of alcohol, alkyl cellosolve, ketone solvent, ether solvent). It is a polyester-based resin that can take the form of an aqueous solution by dissolving in , or a form of an aqueous dispersion dispersed as an emulsion in water.
A polyester-based resin is a resin obtained by a method of polycondensing a dicarboxylic acid (or a dicarboxylic acid ester) and a diol while esterifying (or transesterifying) them.
The water-based polyester-based resin (α) is a polyester-based resin to which water-based properties (water-soluble or water-dispersible) are imparted.

The glass transition temperature (Tg) of the water-based polyester resin (α) is 50°C or higher, preferably 70°C or higher, more preferably 90°C or higher. Although there is no particular upper limit, the glass transition temperature (Tg) of the water-based polyester resin (α) is usually 150° C. or less.
When a hydrophilic composition containing an aqueous polyester resin having a glass transition temperature (Tg) of less than 50° C. is used, it becomes difficult to obtain a hydrophilic sheet having excellent anti-blocking properties.

The weight average molecular weight (Mw) of the water-based polyester resin (α) is generally 2,000 to 100,000, preferably 2,500 to 80,000, more preferably 5,000 to 50,000.
The value of this mass average molecular weight (Mw) is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method.

The water contact angle of the water-based polyester resin (α) is generally 10 to 85°, preferably 25 to 80°, more preferably 40 to 75°.
The water contact angle of the water-based polyester resin (α) can be measured using, for example, a fully automatic contact angle measuring device (DM-701, manufactured by Kyowa Interface Science Co., Ltd.).
The acid value of the water-based polyester resin (α) is usually 0.1-60 mgKOH/g, preferably 0.5-15 mgKOH/g.
The acid value of the water-based polyester resin (α) can be measured, for example, by neutralization point titration using an indicator such as a phenolphthalein solution and an alkaline solution such as a potassium hydroxide solution.

The water-based polyester resin (α) usually has a hydrophilic group in its molecule.
Hydrophilic groups contained in the water-based polyester resin (α) include sulfo groups (--SO ₃ H), carboxy groups (--CO ₂ H), phosphonic acid groups (--PO ₃ H ₂ ), hydroxy groups (--OH ), an anionic hydrophilic group such as a group obtained by reacting these groups with a base; a substituted or unsubstituted amino group, a substituted or unsubstituted nitrogen-containing heterocyclic group, and these groups reacted with an acid cationic hydrophilic groups such as groups;
Among these, as the hydrophilic group, an anionic hydrophilic group is preferable, and -SO ₃ H, -CO ₂ H, -PO ₃ H ₂ , or a group formed by reacting these groups with a base (hereinafter referred to as " A group obtained by reacting these groups with a base is sometimes referred to as an "anionic hydrophilic group (β)".) is more preferable.

Examples of the base used to generate the anionic hydrophilic group (β) include metal hydroxides of Group 1 or Group 2 of the periodic table and amine compounds. Therefore, the water-based polyester resin (α) having an anionic hydrophilic group (β) usually has metal ions or ammonium ions of Group 1 or Group 2 of the periodic table, and the water-based polyester resin (α ) is electrically neutral as a whole.

Specific examples of the water-based polyester resin (α) include polymers having repeating units represented by the following formula (5).

In formula (5), Ar represents a trivalent aromatic group, X represents a hydrophilic group, and Y represents an alkylene group or an arylene group.

The number of carbon atoms in the aromatic group represented by Ar is generally 6-20, preferably 6-15, more preferably 6-10.

Examples of the aromatic group represented by Ar include groups represented by the following formulas and those in which hydrogen atoms are substituted.

In the formula, a ₁ to a ₁₀ represent bonds with carbon atoms (carbon atoms in C═O bond) contained in the main chain of the water-based polyester resin (α). X represents a hydrophilic group and is bonded to any carbon atom in the aromatic ring.
When the aromatic group represented by Ar has a substituent, examples of the substituent include an alkyl group, a phenyl group, an alkoxy group, and a halogen atom.

Examples of the hydrophilic group represented by X include those described above. Among these, —SO ₃ H, —CO ₂ H, —PO ₃ H ₂ , or groups obtained by reacting these groups with a base are preferred.

The alkylene group represented by Y usually has 1 to 20 carbon atoms, preferably 2 to 10 carbon atoms.
The alkylene group represented by Y includes linear alkylene groups such as a methylene group, ethylene group, trimethylene group, tetramethylene group and pentamethylene group; propane-1,2-diyl group and butane-1,3-diyl branched chain alkylene groups such as Among these, a linear alkylene group is preferable, and an ethylene group is more preferable.

The number of carbon atoms in the arylene group represented by Y is usually 6-20, preferably 6-15, more preferably 6-10.
Examples of the arylene group represented by Y include groups represented by the following formulas, and those in which hydrogen atoms are substituted.

In the formula, b ₁ to b ₁₀ represent bonds with oxygen atoms contained in the main chain of the water-based polyester resin (α).
When the arylene group represented by Y has a substituent, examples of the substituent include an alkyl group, a phenyl group, an alkoxy group, and a halogen atom.

As the repeating unit represented by the above formula (5), those represented by the following formula (5a) are preferable, and those represented by (5b) are more preferable.

In formula (5a), X has the same meaning as above. In formula (5b), M represents an alkali metal ion, preferably a sodium ion.

Further, when the water-based polyester resin (α) has a repeating unit represented by the above formula (5), it may contain one or more repeating units represented by the above formula (5). , may have a repeating unit other than the repeating unit represented by the above formula (5).
Repeating units other than the repeating unit represented by the above formula (5) include repeating units derived from (meth)acrylic acid esters such as acrylic acid esters and methacrylic acid esters, and repeating units of the above formula (5) except that they do not have X. ) having the same structure as the repeating unit represented by ). Among them, a repeating unit having a structure represented by the following formula is preferable.

The amount of the repeating unit represented by the above formula (5) contained in the aqueous polyester resin (α) is usually 40 to 100% by mass, preferably 60 to 100% by mass, based on the total amount of the aqueous polyester resin (α). , more preferably 80 to 100% by mass, particularly preferably 95 to 100% by mass.

The water-based polyester-based resin (α) can be obtained by imparting water-based properties to the polyester-based resin.
The polyester-based resin can be obtained by a conventionally known production method such as a method of polycondensing a dicarboxylic acid (or dicarboxylic acid ester) and a diol while esterifying (or transesterifying) them.
Dicarboxylic acids or dicarboxylic acid esters include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid and naphthalenedicarboxylic acid and their esters; aliphatic dicarboxylic acids such as adipic acid, succinic acid, sebacic acid and dodecanedioic acid; esters thereof; alicyclic dicarboxylic acids such as cyclohexyldicarboxylic acid and esters thereof; hydroxycarboxylic acids such as hydroxybenzoic acid and esters thereof; Among these, aromatic dicarboxylic acids or esters thereof are preferred.
Dicarboxylic acid esters include lower alkyl esters of dicarboxylic acids such as methyl esters and ethyl esters of dicarboxylic acids. These esters may be monoesters or diesters.

Diols include ethylene glycol, propylene glycol, trimethylene glycol, 4-butanediol, 1,6-hexanediol, neopentyl glycol, 2, cyclohexanedimethanol, bisphenols and the like.

As a method of obtaining a water-soluble polyester resin (α) by imparting water to a polyester resin, for example, when producing a polyester resin, in addition to the above dicarboxylic acid and polyol, a hydrophilic group is added to the molecule. A method of polymerizing a monomer can be mentioned.

As the monomer having a hydrophilic group in the molecule, a dicarboxylic acid having a hydrophilic group or a dicarboxylic acid ester having a hydrophilic group is preferable. A water-based polyester resin (α) having a hydrophilic group can be obtained by a method using a dicarboxylic acid having a hydrophilic group as a dicarboxylic acid component.

More specifically, the water-based polyester resin (α) having a repeating unit represented by the formula (5) is a compound having a carboxyl group and a hydrophilic group represented by the following formula (5c) and a compound represented by the following formula (5d ) can be synthesized by polycondensation reaction with a hydroxyl group-containing compound represented by ) according to a conventional method.

In formulas (5c) and (5d), Ar, X and Y each have the same meaning as above.

In addition, water-soluble salts such as alkali metals, various amines, and ammonium compounds can be added to polyester resins having anionic hydrophilic groups such as sulfo or carboxy groups (excluding anionic hydrophilic groups (β)). A water-based polyester resin having an anionic hydrophilic group (β) can be obtained by allowing the substance to be formed to act.

The obtained reaction solution may be used as it is for the preparation of the hydrophilic composition, or the water-based polyester resin (α) may be isolated and purified according to a conventional method.

Moreover, the water-based polyester resin (α) may be a modified polyester resin. Examples of modified polyester-based resins include acrylic-modified polyester-based resins, urethane-modified polyesters, epoxy-modified polyester-based resins, glycol-modified polyester-based resins, and the like.
Among these, acrylic-modified polyester-based resins are preferred because they facilitate the formation of a hydrophilic layer having an excellent balance of hydrophilicity and anti-blocking properties. Examples of acrylic-modified polyester-based resins include graft copolymers having polyester chains as main chains and polymer chains derived from acrylic monomers as side chains.

Modified polyester resin can be obtained by a method of modifying the polymer (unmodified aqueous polyester resin) obtained by the above method by a known method, etc., to obtain the desired modified polyester resin. . For example, an acrylic-modified polyester-based resin is obtained by reacting a monomer having an epoxy group and a polymerizable double bond, such as glycidyl methacrylate, with an unmodified water-based polyester-based resin having a carboxy group or the like. A polymerizable double bond is introduced into the water-based polyester resin, and then, using this polymerizable double bond, an acrylic monomer is polymerized to form a side chain (a polymer derived from the acrylic monomer can be synthesized by forming a chain).

In the present invention, the water-based polyester resin (α) may be used alone or in combination of two or more.

[Hydrophilic composition]
The hydrophilic composition of the present invention contains the components (A) and (B).
The content of component (B) is 60 to 152 parts by mass, preferably 70 to 150 parts by mass, more preferably 80 to 120 parts by mass, per 100 parts by mass of component (A).

By using a hydrophilic composition in which the ratio of components (A) and (B) is within the above range, a hydrophilic sheet excellent in both hydrophilicity and blocking resistance can be efficiently produced.

The hydrophilic composition of the invention usually contains a solvent. Examples of the solvent include water; alcohol solvents such as methanol, ethanol and isopropanol; cellosolve solvents such as methoxyethanol; ketone solvents such as acetone;

In the hydrophilic composition of the present invention, the solvent can be used singly or in combination of two or more.
The content of the solvent is preferably adjusted so that the solid content concentration of the hydrophilic composition of the present invention is 0.5 to 30% by mass, and 1 to 10% by mass is preferable from the viewpoint of handleability and coating suitability. more preferred.

The hydrophilic composition of the present invention may contain resin components other than the components (A) and (B) (hereinafter sometimes referred to as "other resin components").
Other resin components include ethylene-vinyl alcohol copolymer, vinyl alcohol homopolymer, (meth)acrylic acid polymer, (meth)acrylic acid ester polymer, polyamide resin, polyolefin resin, cellulose resin, etc. is mentioned.

In the hydrophilic composition of the present invention, other resin components may be used singly or in combination of two or more.
When the hydrophilic composition of the present invention contains other resin components, the content thereof is usually 50 parts by mass or less, preferably 40 parts by mass or less per 100 parts by mass of component (A).

The hydrophilic composition of the present invention may contain an ionic compound having a cation having 0 to 10 carbon atoms as component (C). By containing the component (C), the storage stability of the hydrophilic composition may be improved.

Component (C) is preferably an ionic compound having a cation with 0 to 5 carbon atoms, more preferably an ionic compound having a cation with 0 carbon atoms.

Examples of the ionic compound having a cation having 0 to 10 carbon atoms include compounds represented by the following formulas (12) to (15).

In formulas (12) to (15), M represents a monovalent cation having 0 to 10 carbon atoms, M′ represents a divalent cation having 0 to 10 carbon atoms, and X is a monovalent anion. and X' represents a divalent anion.

Examples of M include alkali metal ions such as sodium ion and potassium ion; ammonium ion (NH ₄ ⁺ ); primary ammonium ion; secondary ammonium ion; tertiary ammonium ion; be done.
Examples of M′ include alkaline earth metal ions such as calcium ions; magnesium ions; and the like.
Examples of X include halide ions such as chloride ion and bromide ion; bicarbonate ion; nitrate ion; and the like.
X′ includes carbonate ion, sulfate ion, and the like.

Examples of ionic compounds having a cation having 0 carbon atoms include NaCl, _Na2CO3 , _NaHCO3 , _Na2SO4 , _{NaNO3 ,} KCl, _{K2CO3 , KHCO3 , K2SO4 , KNO3} . magnesium salts such as MgCl ₂ , MgSO ₄ ; alkaline earth metal salts such as CaCl ₂ ; ammonium salts such as NH ₄ Cl;
Examples of ionic compounds having cations having 1 to 10 carbon atoms include [(CH ₃ )NH ₃ ]Cl, [(CH ₃ ) ₂ NH ₂ ]Cl, [(CH ₃ ) ₃ NH]Cl, [( CH ₃ ) ₄ N]Cl and the like.

The ionic compounds having a cation with 0 to 10 carbon atoms can be used singly or in combination of two or more.
The content of the ionic compound having a cation having 0 to 10 carbon atoms in the hydrophilic composition is usually 1 to 70 parts by mass, preferably 2 to 50 parts by mass, per 100 parts by mass of component (A). parts, more preferably 5 to 20 parts by mass.

The hydrophilic composition of the present invention may contain a cross-linking agent as component (D).
The cross-linking agent is a compound capable of forming a cross-linked structure by reacting with the resin component constituting the hydrophilic composition of the present invention.
A hydrophilic layer having excellent water resistance can be formed by using a hydrophilic composition containing a cross-linking agent.

Examples of cross-linking agents include epoxy-based cross-linking agents, isocyanate-based cross-linking agents, amine-based cross-linking agents, melamine-based cross-linking agents, aziridine-based cross-linking agents, hydrazine-based cross-linking agents, aldehyde-based cross-linking agents, oxazoline-based cross-linking agents, and metal alkoxide-based cross-linking agents. , metal chelate cross-linking agents, metal salt cross-linking agents, ammonium salt cross-linking agents, and the like.

Among these, an epoxy-based cross-linking agent is preferable as the cross-linking agent because a hydrophilic composition capable of forming a hydrophilic layer having excellent water resistance can be obtained.
Epoxy cross-linking agents include bisphenol A/epichlorohydrin type epoxy resin, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether. , neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, diglycidyl aniline , N,N,N′,N′-tetraglycidyl-m-xylenediamine, 1,3-bis(N,N′-diglycidylaminomethyl)cyclohexane, and the like.

In the hydrophilic composition of the present invention, the cross-linking agent can be used singly or in combination of two or more.
When the hydrophilic composition of the present invention contains a cross-linking agent, the content thereof is preferably 0.1 to 20 parts by mass, more preferably 1 to 10 parts by mass, per 100 parts by mass of component (A). part by mass.

The hydrophilic composition of the present invention may contain additives as long as they do not impair the effects of the present invention.
Additives include surfactants, humectants, viscosity modifiers, pigments, and the like.

Of the solid content of the hydrophilic composition of the present invention, the total amount of components (A) and (B) is preferably 50 to 100% by mass, preferably 70 to 100% by mass, based on the total amount of the components. more preferably 90 to 100% by mass.
The hydrophilic composition of the present invention can be prepared by mixing the above ingredients using known methods.

The hydrophilic composition of the present invention is suitably used for hydrophilizing solid surfaces.
The solid to be hydrophilized is not particularly limited. Types of solids include inorganic materials such as glass, pottery, porcelain, enamel, tiles, and ceramics; metals such as aluminum, stainless steel, and brass; polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyvinyl chloride, and polycarbonate. , synthetic resins such as acrylic resins and styrene resins; natural fibers such as cotton, pulp, silk and wool;

The solid surface may be previously subjected to a hydrophilization treatment.
Hydrophilic treatment includes physical surface treatment such as corona treatment, plasma treatment and ultraviolet treatment; chemical surface treatment such as acid contact; formation of a primer layer; and the like.
However, according to the hydrophilic composition of the present invention, it is possible to form a hydrophilic layer having excellent adhesion to the solid surface without performing such a hydrophilic treatment.

The shape of the solid to be hydrophilized is not particularly limited. However, since a hydrophilic sheet excellent in both hydrophilicity and blocking resistance can be obtained by using the hydrophilic composition of the present invention, the solid to be hydrophilized is preferably in the form of a sheet.

When the hydrophilic composition of the present invention is used to hydrophilize a solid surface, usually, the hydrophilic composition of the present invention is brought into contact with the solid surface to form a coating film, and then the coating film is dried to be hydrophilic. form the sexual layer.

Examples of the method of bringing the hydrophilic composition into contact with the solid surface include a method of immersing the solid in the hydrophilic composition and a method of spraying or coating the hydrophilic composition on the solid surface.

A method for drying the coating film is not particularly limited. For example, conventionally known drying methods such as hot air drying, hot roll drying, and infrared irradiation can be used.
The drying temperature of the coating film is usually 30 to 150°C, preferably 50 to 100°C. The heating time is usually 5 seconds to 10 minutes, preferably 20 seconds to 5 minutes, more preferably 40 seconds to 2 minutes.
After drying, if necessary, it is preferable to leave the solid on which the hydrophilic layer is formed in an appropriate environment and subject it to a seasoning treatment.

The thickness of the hydrophilic layer is usually 0.1-5 μm, preferably 0.5-3 μm.
The water contact angle of the hydrophilic layer is usually 15-50°, preferably 20-40°.

By forming a hydrophilic layer using the hydrophilic composition of the present invention, it is possible to prevent fogging of the article to be coated (the above-mentioned solid) and to efficiently improve the antifouling property of the article to be coated. can be done.

2) Hydrophilic sheet The hydrophilic sheet of the present invention is formed by laminating a hydrophilic layer directly or via another layer on a base sheet, wherein the hydrophilic layer is the hydrophilic sheet of the present invention. It is formed using a sexual composition.

The base sheet constituting the hydrophilic sheet of the present invention is not particularly limited as long as it can support the hydrophilic layer.
Examples of the base sheet include resin sheets, metal foils, inorganic sheets, paper, and laminates thereof.

Examples of the resin constituting the resin sheet include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate, polybutylene terephthalate and polynaphthalene terephthalate; polyvinyl chloride; polycarbonates; acrylic resins;

The resin sheet may contain additives such as ultraviolet absorbers, light stabilizers and antioxidants.
The surface of the resin sheet may be subjected to hydrophilic treatment.
Examples of the hydrophilization treatment include those described above.

Aluminum, stainless steel, copper, nickel, iron, etc. are mentioned as a metal which comprises metal foil.
Glass etc. are mentioned as an inorganic compound which comprises an inorganic sheet.
The thickness of the base sheet is usually 20-200 μm, preferably 30-100 μm.

The hydrophilic layer constituting the hydrophilic sheet of the invention is a layer formed using the hydrophilic composition of the invention.
The hydrophilic layer in the hydrophilic sheet can be formed using the methods previously described.
The preferred thickness and water contact angle of the hydrophilic layer in the hydrophilic sheet are the same as those described above.

In the case where the hydrophilic sheet of the present invention is formed by forming a hydrophilic layer on a base sheet with another layer interposed therebetween, the other layer includes a layer containing a siloxane-based polymer.
A siloxane-based polymer is a polymer having a siloxane bond (Si—O—Si). A siloxane-based polymer can usually be obtained by hydrolytic polycondensation of a hydrolyzable organosilicon compound. The term "hydrolyzable" refers to the property of forming silanol groups upon reaction with water.

Depending on the surface condition of the base sheet, the formed hydrophilic layer may have poor adhesion to the base sheet. This problem of adhesion of the hydrophilic layer can be solved by providing a layer containing a siloxane-based polymer under the hydrophilic layer.

The layer containing a siloxane-based polymer is obtained, for example, by applying a coating liquid containing a precursor compound of a siloxane-based polymer (a hydrolyzable organosilicon compound such as tetraalkoxysilane) onto a substrate sheet, and obtaining a coating. It can be formed by hydrolyzing and polycondensing the hydrolyzable organosilicon compound in the film to form a coating film containing the siloxane-based polymer, and then drying the coating film.
As the coating liquid containing the precursor compound of the siloxane-based polymer, a commercially available product known as so-called alcoholic silica sol may be used.

Further, by allowing the siloxane-based polymer in the layer containing the siloxane-based polymer and the resin component in the hydrophilic layer to be entangled at the interface between both layers, it is possible to form a hydrophilic layer with more excellent adhesion. .

In order to increase the entanglement between the siloxane polymer at the interface and the resin component in the hydrophilic layer, the coating film containing the siloxane polymer is in a semi-dry state (a state in which the solvent remains), and the present The hydrophilic composition of the invention may be applied to form a coating film, and then these coating films may be dried to simultaneously form the other layers and the hydrophilic layer.

The thickness of other layers is usually 10 to 10,000 nm, preferably 30 to 5,000 nm, more preferably 50 to 500 nm.

The hydrophilic sheet of the present invention has a hydrophilic layer formed using the hydrophilic composition of the present invention.
Therefore, the hydrophilic sheet of the present invention is excellent in both hydrophilicity and blocking resistance.

EXAMPLES The present invention will be described in more detail below with reference to examples. However, the present invention is by no means limited to the following examples.
Parts and % in each example are based on mass unless otherwise specified.

[Mass average molecular weight (Mw)]
The mass average molecular weight (Mw) of the zwitterionic polymer was determined by gel permeation chromatography (GPC) under the following conditions.

Apparatus: HLC-8320GPC / UV-8320 (manufactured by Tosoh Corporation)
Column: TSKgelGMPW _XL (manufactured by Tosoh Corporation) x 2
Detector: HLC-8320GPC built-in RI detector / UV-8320 (manufactured by Tosoh Corporation)
Column temperature: 40°C
Sample concentration: 1.0 g / L (polymer component concentration)
Injection volume: 100 μL
Eluent: 0.2 M _NaNO3 aqueous solution Flow rate: 1.0 mL/min Molecular weight marker: standard polyethylene oxide, polyethylene glycol

[Production Example 1] Synthesis of zwitterionic monomer Into a reaction vessel equipped with a stirrer, 100 parts of N-[3-(dimethylamino)propyl]acrylamide, 0.4 parts of dibutylhydroxytoluene, and 267 parts of acetone were charged. 78 parts of propanesultone was slowly added dropwise while the mixture was stirred. After that, the content was stirred at 25° C. for 24 hours, and the precipitated white solid was collected by filtration and dried to give a zwitterionic monomer (N-acryloylaminopropyl-N,N-dimethylammoniumpropyl-α- sulfoxybetaine) was obtained.

[Production Example 2] Synthesis of zwitterionic polymer In a reaction vessel equipped with a stirrer, 98.7 parts of N-acryloylaminopropyl-N,N-dimethylammoniumpropyl-α-sulfoxybetaine and 1.3 parts of acrylic acid were added. , Polymerization initiator (manufactured by Wako Pure Chemical Industries, Ltd., product name "V-501", 4,4'-azobis (4-cyanovaleric acid)) 0.21 parts, distilled water 234 parts, put in the reaction vessel The mixture was stirred at 25°C for 30 minutes while nitrogen was introduced into the solution. After that, the inside of the system was raised to 80° C. and stirred for 12 hours to carry out a polymerization reaction, thereby obtaining a solution containing a zwitterionic polymer. The resulting zwitterionic polymer had a weight average molecular weight of 720,000.

[Example 1]
The solution containing the zwitterionic polymer obtained in Production Example 2 (solid content: 100 parts), sodium chloride: 17 parts, water-based polyester resin (1)-containing liquid [manufactured by GOO CHEMICAL INDUSTRY CO., LTD., product name: "Plascoat RZ-105" (solid content concentration 25%)] (solid content 100 parts) is added, distilled water is added to adjust the solid content concentration to 2.0%, and this is sufficiently stirred to form a hydrophilic composition. got

Base sheet (polyester film, manufactured by Mitsubishi Chemical Corporation, product name "Diafoil", thickness 50 μm), alcoholic silica sol (manufactured by Colcoat Co., Ltd., product name "N-103X", solid content concentration 2.0% ) was applied using a wire bar so that the thickness after drying was 100 nm, and the resulting laminate was heated at 100° C. for 1 minute to form a layer containing a siloxane-based polymer.
Then, the hydrophilic composition is applied onto the layer containing the siloxane-based polymer, and the resulting coating film is heated at 100° C. for 1 minute to form a hydrophilic layer having a thickness of 1 μm. Got a sex sheet.

[Examples 2 to 7, Comparative Examples 1 to 3]
A hydrophilic composition and a hydrophilic sheet were obtained in the same manner as in Example 1, except that the types and amounts of each component were changed as shown in Table 1.
In addition, in each example, the following commercial items were used.
Liquid containing water-based polyester resin (1): manufactured by GOO CHEMICAL INDUSTRY CO., LTD., product name “Plascoat RZ-105” (solid content concentration 25%), Tg 54° C., molecular weight 16,000
Liquid containing water-based polyester resin (2): manufactured by GOO CHEMICAL INDUSTRY CO., LTD., product name “Plascoat Z-760” (solid content concentration 25%), Tg 52° C., molecular weight 3,000
Liquid containing water-based polyester resin (3): manufactured by GOO CHEMICAL INDUSTRY CO., LTD., product name “Plascoat Z-687” (solid content concentration 25%), Tg 110° C., molecular weight 26,000
Liquid containing water-based polyester resin (4): manufactured by GOO CHEMICAL INDUSTRY CO., LTD., product name “Plascoat Z-690” (solid content concentration 25%), Tg 110° C., molecular weight 28,000
Liquid containing water-based polyester resin (5): manufactured by Toyobo Co., Ltd., product name "MD-1245" solid content concentration 30%), Tg 64 ° C., molecular weight 20,000
Liquid containing water-based polyester resin (6): manufactured by GOO CHEMICAL INDUSTRY CO., LTD., product name “Plascoat Z-221” (solid content concentration 20%), Tg 47° C., molecular weight 14,000

[Water contact angle measurement]
2 μL of ion-exchanged water was dropped onto the hydrophilic layers of the hydrophilic sheets obtained in Examples and Comparative Examples. Using a fully automatic contact angle measuring device (Drop Master, DM-701, manufactured by Kyowa Interface Science Co., Ltd.), the water contact angle of the water droplet was measured 3 seconds after dropping.

[Blocking resistance evaluation]
The hydrophilic sheets obtained in Examples and Comparative Examples were cut into three squares each having a side of 5 cm. After stacking these, a weight of 2 kg was placed. After allowing this to stand in an environment of a temperature of 40° C. and a relative humidity of 80% for one week, the presence or absence of sticking between the hydrophilic sheets was examined, and the blocking resistance was evaluated according to the following criteria.
A: No sticking B: Slightly sticking C: Sticking

Table 1 shows the following.
The hydrophilic sheets obtained in Examples 1 to 7 have a small water contact angle and excellent hydrophilicity. Furthermore, these hydrophilic sheets are also excellent in blocking resistance.
On the other hand, the hydrophilic sheet obtained in Comparative Example 1 was obtained using a hydrophilic composition containing an aqueous polyester-based resin having a low glass transition temperature, and thus was inferior in blocking resistance.
Further, the hydrophilic sheets obtained in Comparative Examples 2 and 3 were obtained using a hydrophilic composition containing a small amount of water-based polyester resin, and therefore were inferior in blocking resistance.

Claims (6)

A hydrophilic composition containing the following components (A) and (B), wherein the content of component (B) is 60 to 152 parts by mass relative to 100 parts by mass of component (A) sex composition.
Component (A): A zwitterionic polymer having 50 to 100 mol% of the total polymer, repeating units represented by the following formula (1)

[In the formula, R ¹ represents a hydrogen atom or a methyl group, R ² and R ³ each independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms with or without an ether bond, or an ether bond or without a cyanoalkyl group having 2 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms with or without an ether bond, or an aryl group having 6 to 10 carbon atoms with or without a substituent. Also, R ² and R ³ may combine with each other to form a ring. A ¹ is the following formula (2) or (3)

(wherein A ² and A ³ each independently represent an alkylene group having 1 to 10 carbon atoms with or without a substituent; R ⁴ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or , represents an aryl group having 6 to 10 carbon atoms with or without a substituent, n represents an integer of 1 to 10, *1 represents a bond with a carbon atom, and *2 represents a bond with a nitrogen atom. represents.)
represents a divalent group represented by any one of —G ^— represents a deprotonated sulfo group (—SO ₃ ⁻ ). m represents an integer of 2 to 5; ]
(B) component: water-based polyester resin having a glass transition temperature (Tg) of 50°C or higher The zwitterionic polymer of component (A) has a repeating unit having a carboxy group, a sulfo group, or a group formed by reacting these groups with a base (excluding repeating units derived from zwitterionic monomers). The hydrophilic composition according to claim 1, which is a polymer having The water-based polyester resin of the component (B) is represented by the following formula (5)

(In the formula, Ar represents a trivalent aromatic group, X represents a hydrophilic group, and Y represents an alkylene group or an arylene group.)
3. The hydrophilic composition according to claim 1 or 2, which is a polymer having a repeating unit represented by: 4. The hydrophilic composition according to claim 3, wherein the hydrophilic group represented by X is -SO ₃ H, -CO ₂ H, -PO ₃ H ₂ , or a group obtained by reacting these groups with a base. thing. 5. The hydrophilic composition according to any one of claims 1 to 4, further comprising the following component (C).
Component (C): an ionic compound having a cation with 0 to 10 carbon atoms A hydrophilic sheet obtained by laminating a hydrophilic layer directly or via another layer on a base sheet,
A hydrophilic sheet, wherein the hydrophilic layer is formed using the hydrophilic composition according to any one of claims 1 to 5.