JP2019119871A - Active energy ray-curable composition and hydrogel obtained by curing the same - Google Patents

Abstract

To provide an active energy ray-curable composition which has good handleability with low viscosity and is capable of forming a hydrogel.SOLUTION: The active energy ray-curable composition is obtained by mixing: a water-absorbing resin (A) in the form of particles having a volume average particle diameter of 10-60 μm, which contains a crosslinked polymer obtained from a water-soluble vinyl monomer and/or a vinyl monomer becoming a water-soluble vinyl monomer by hydrolysis and a crosslinking agent; a monomer component (B) containing a water-soluble monofunctional vinyl monomer and a bifunctional (meth)acrylate represented by formula (1); a photoradical polymerization initiator (C); and water. [Rand Reach independently represent a methyl group or a hydrogen atom; and n is an integer of 4-60.]SELECTED DRAWING: None

Description

  The present invention relates to an active energy ray-curable composition and a hydrogel obtained by curing the same.

  Since hydrogels are excellent in properties such as water absorbency, water retention and flexibility, they can be applied to various technical fields such as medicine, food, construction and civil engineering as water absorbent materials, water retention materials, industrial materials and biosubstitutable materials etc. It is expected. In particular, in the case of using a hydrogel as a molded article, a hydrogel having a flexibility capable of restoring its shape when released by applying an external force, and a high strength are required.

As such a flexible and strong hydrogel, a hydrogel based on a combination of a hard and brittle first gel and a soft second gel (double network structure) is disclosed (see, for example, Patent Document 1).
Also, in order to improve the formability of the hydrogel having a double network structure, the first gel is dried and crushed and used as a powder, and the second gel aqueous solution is swollen in the first gel to be paste-like and cured. A hydrogel composition is disclosed (see, for example, Patent Document 2).

However, since the hydrogel of Patent Document 1 can be formed only in the form of the first gel, the formability is poor, and irradiation with a UV lamp is required for several hours under a nitrogen atmosphere to form a gel, and the gel There is a problem that it takes a lot of time to manufacture the
In the hydrogel of Patent Document 2, the viscosity of the paste is high and the handling property is poor, and the particles of 100 μm are swollen, so the particle size after swelling becomes large and the surface smoothness is poor. In a nitrogen atmosphere, irradiation with a UV lamp is required for several hours, and there is a problem that it takes a long time to produce a gel.

Patent No. 4382297 JP, 2009-217037, A

  The present invention has been made in view of the above problems, and an object of the present invention is to form a hydrogel which has a low viscosity and good handling properties, and can be cured with a small dose of active energy ray. It is an object of the present invention to provide an active energy ray curable composition.

  The present inventors reached the present invention as a result of earnestly examining in order to solve the above-mentioned object. That is, according to the present invention, a crosslinked polymer (A1) comprising a water-soluble vinyl monomer (a1) and / or a vinyl monomer (a2) which becomes a water-soluble vinyl monomer (a1) by hydrolysis and a crosslinking agent (a4) as essential constitutional units A water-absorbing resin (A) which is a particulate having a volume average particle diameter of 10 to 60 μm, and a water-soluble monofunctional vinyl monomer (b1) and the general formula (1) An active energy ray-curable composition obtained by mixing a monomer component (B) containing a bifunctional (meth) acrylate (b2), a photoradical polymerization initiator (C), and water; the above-mentioned active energy ray-curable It is a hydrogel obtained by curing the composition.

［式中、Ｒ¹及びＲ²はそれぞれ独立にメチル基又は水素原子を表し、ｎは４〜６０の整数を表す。］

[In Formula, R < ¹ > and R < ² > respectively independently represent a methyl group or a hydrogen atom, n represents the integer of 4-60. ]

  The active energy ray-curable composition of the present invention has low viscosity and good handling properties, and can form a hydrogel that can be cured with a small amount of active energy ray irradiation. Moreover, the hydrogel obtained by hardening the active energy ray curable composition of this invention is excellent in transparency.

  The active energy ray-curable composition of the present invention comprises a water-absorbent resin (A) in the form of particles having a volume average particle diameter of 10 to 60 μm, a water-soluble monofunctional vinyl monomer (b1) and a general formula (1). The monomer component (B) containing the bifunctional (meth) acrylate (b2) to be mixed, the radical photopolymerization initiator (C), and water are mixed.

  The water-absorbent resin (A) in the present invention comprises a water-soluble vinyl monomer (a1) and / or a vinyl monomer (a2) which becomes a water-soluble vinyl monomer (a1) by hydrolysis and a crosslinking agent (a4) as essential constitutional units. It contains a crosslinked polymer (A1).

  The water-soluble vinyl monomer (a1) is not particularly limited, and known monomers, for example, at least one water-soluble substituent and an ethylenically unsaturated group disclosed in paragraphs 0007 to 0023 of JP 3648553 A. Monomers having the following properties (for example, anionic vinyl monomers, nonionic vinyl monomers and cationic vinyl monomers), anionic vinyl monomers disclosed in JP-A No. 2003-165883, paragraphs 0009 to 0024, nonionic vinyl monomers And cationic vinyl monomers, and at least one member selected from the group consisting of carboxy group, sulfo group, phosphono group, hydroxyl group, carbamoyl group, amino group and ammonio group disclosed in paragraphs 0041 to 0051 of JP 2005-75982A. Vinyl moth with seeds Mer can be used.

A vinyl monomer (a2) [hereinafter, also referred to as a hydrolyzable vinyl monomer (a2), which becomes a water-soluble vinyl monomer (a1) by hydrolysis]. There is no particular limitation, and publicly known {for example, a vinyl monomer having at least one hydrolyzable substituent which becomes a water-soluble substituent by hydrolysis disclosed in paragraphs 0024 to 0025 of Japanese Patent No. 3648553, JP-A At least one hydrolysable substituent [1,3-oxo-2-oxapropylene (-CO-O-CO-) group, an acyl group and a cyano group disclosed in paragraphs 0052 to 0055 of 2005-75982]. Vinyl monomers having a group etc.] can be used.
The "water-soluble" in the water-soluble vinyl monomer (a1) and the water-soluble monofunctional vinyl monomer (b1) described below means that at least 100 g of the vinyl monomer is dissolved in 100 g of water at 25 ° C (the solubility in water is at least 100 g / Means 100g of water). The water-soluble vinyl monomer (a1) and the water-soluble monofunctional vinyl monomer (b1) described later are preferably miscible vinyl monomers which are optionally dissolved in water. Moreover, the hydrolysability in a hydrolysable vinyl monomer (a2) means the property which is hydrolyzed by the effect | action of water and the catalyst (acid or base etc. if necessary), and becomes water solubility. The hydrolysis of the hydrolyzable vinyl monomer (a2) may be performed during polymerization, after polymerization, or both of them, but after polymerization is preferred from the viewpoint of the absorption performance of the resulting absorbent resin.

  Among these, water-soluble vinyl monomers (a1) are preferred from the viewpoint of absorption performance etc., more preferably vinyl monomers having a carboxy (salt) group, a sulfo (salt) group, an amino group, a carbamoyl group or an ammonio group, Further preferred are vinyl monomers having a carboxy (salt) group or a carbamoyl group, particularly preferred is (meth) acrylic acid (salt) and (meth) acrylamide, particularly preferred is (meth) acrylic acid (salt), most preferred Is acrylic acid (salt). Each of (a1) and (a2) may be used alone or in combination of two or more.

  Here, "carboxy (salt) group" means "carboxy group" or "carboxylate group", and "sulfo (salt) group" means "sulfo group" or "sulfonate group". Also, (meth) acrylic acid (salt) means acrylic acid, acrylic acid salt, methacrylic acid or methacrylic acid salt, and (meth) acrylamide means acrylamide or methacrylamide. Moreover, as a salt, alkali metal (lithium, sodium and potassium etc.) salt, alkaline earth metal (magnesium and calcium etc.) salt, ammonium salt etc. are mentioned. Among these salts, alkali metal salts and ammonium salts are preferable from the viewpoint of absorption performance etc., more preferable are alkali metal salts, and particularly preferable are sodium salts.

  When either a water-soluble vinyl monomer (a1) or a hydrolyzable vinyl monomer (a2) is used as a structural unit, one type may be used alone as a structural unit, and two or more types may also be used as a structural unit as necessary. Good. The same applies to the case where the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are used as structural units. When the water-soluble vinyl monomer (a1) and the hydrolyzable vinyl monomer (a2) are structural units, their content molar ratio [(a1) / (a2)] is preferably 75 in terms of absorption performance. / 25 to 99/1, more preferably 85/15 to 95/5, particularly preferably 90/10 to 93/7, most preferably 91/9 to 92/8.

  In addition to the water-soluble vinyl monomer (a1) and / or the hydrolyzable vinyl monomer (a2) as the constituent units of the crosslinked polymer (A1), other vinyl monomers (a3) copolymerizable therewith are can do. As (a3), one type may be used alone, or two or more types may be used in combination.

There is no particular limitation on the copolymerizable other vinyl monomer (a3), and known vinyl monomers (for example, hydrophobic vinyl monomers disclosed in paragraphs 0028 to 0029 of Japanese Patent No. 3648553, Japanese Patent Laid-Open Nos. 2003-165883 and Hydrophobic vinyl monomers etc. such as vinyl monomers disclosed in paragraph 0058 of JP-A-2005-75982 can be used. Specifically, for example, vinyl monomers of the following (i) to (iii) It can be used.
(I) Aromatic ethylenic monomers having 8 to 30 carbon atoms Styrene, styrene such as α-methylstyrene, vinyl toluene and hydroxystyrene, and halogen-substituted styrenes such as vinyl naphthalene and dichlorostyrene.
(Ii) Aliphatic ethylenic monomers having 2 to 20 carbon atoms: alkenes (ethylene, propylene, butene, isobutylene, pentene, heptene, diisobutylene, octene, dodecene, octadecene, etc.); and alkadienes (butadiene, isoprene etc.), etc.
(Iii) Alicyclic ethylenic monomers having 5 to 15 carbon atoms Monoethylenically unsaturated monomers (pinene, limonene, indene etc.); and polyethylene vinyl monomers [cyclopentadiene, bicyclopentadiene, ethylidene norbornene etc.] etc.

  The content of the other vinyl monomer (a3) unit is 0 to 5 moles based on the total number of moles of the water-soluble vinyl monomer (a1) unit and the hydrolyzable vinyl monomer (a2) unit from the viewpoint of absorption performance etc. %, More preferably 0 to 3 mol%, particularly preferably 0 to 2 mol%, particularly preferably 0 to 1.5 mol%, and from the viewpoint of absorption performance etc., other vinyl monomer (a3) units Most preferably, the content of is 0 mol%.

  The crosslinking agent (a4) is not particularly limited and is known (for example, it reacts with a crosslinking agent having two or more ethylenic unsaturated groups disclosed in paragraphs 0031 to 0034 of Japanese Patent No. 3648553, a water-soluble substituent). JP-A-2003-165883 which has at least one functional group to be obtained and at least one crosslinking agent having at least one ethylenically unsaturated group and at least two functional groups capable of reacting with a water-soluble substituent. The crosslinking agent having two or more ethylenic unsaturated groups, the crosslinking agent having an ethylenic unsaturated group and a reactive functional group, and the crosslinking agent having two or more reactive substituents, disclosed in paragraphs 0028 to 0031 of , Crosslinkable vinyl monomers disclosed in paragraph [0059] of JP-A-2005-75982 and 0015 to 0016 stages of JP-A-2005-95759. Crosslinking agents such as disclosed crosslinkable vinyl monomer) can be used to. Among these, from the viewpoint of absorption performance etc., a crosslinking agent having two or more ethylenic unsaturated groups is preferred, and more preferred are triallyl cyanurate, triallyl isocyanurate and poly of polyols having 2 to 10 carbon atoms. Meta) allyl ethers, particularly preferably triallyl cyanurate, triallyl isocyanurate, tetraaryloxyethane and pentaerythritol triaryl ether, most preferably pentaerythritol triaryl ether. The crosslinking agent (a4) may be used alone or in combination of two or more.

  The content of the crosslinking agent (a4) unit is preferably 0.001 to 5 mol%, and more preferably, based on the total number of moles of the water-soluble vinyl monomer (a1) unit and the hydrolyzable vinyl monomer (a2) unit. 0.005 to 3 mol%, particularly preferably 0.01 to 1 mol%. Within this range, the absorption performance is further improved.

  As a method for producing the crosslinked polymer (A1), known aqueous solution polymerization (diathermal polymerization, thin film polymerization, spray polymerization method, etc .; JP-A-55-133413, etc.) and known reverse phase suspension polymerization (JP-B No. 54-30710, JP-A-56-26909, JP-A-1-5808, etc.) and a water-containing gel polymer [crosslinked polymer (A1) and water. ] Can be obtained by heating and drying, if necessary.

  Among the polymerization methods, the solution polymerization method is preferable, and the aqueous solution polymerization method is particularly preferable since it is not necessary to use an organic solvent etc. and advantageous in terms of production cost, and the water retention amount is large and the water solubility is particularly preferable. The aqueous solution heat insulating polymerization method is most preferable in that an aqueous liquid absorbent resin with a small amount of components is obtained and temperature control at the time of polymerization is unnecessary.

When aqueous solution polymerization is performed, a mixed solvent containing water and an organic solvent can be used, and as the organic solvent, methanol, ethanol, acetone, methyl ethyl ketone, N, N-dimethylformamide, dimethyl sulfoxide and two or more of them can be used. A mixture of
When aqueous solution polymerization is carried out, the amount of the organic solvent used is preferably 40% by weight or less, more preferably 30% by weight or less, based on the weight of water.

When a catalyst is used for the polymerization, conventionally known catalysts for radical polymerization can be used. For example, azo compounds [azobisisobutyronitrile, azobiscyanovaleric acid and 2,2'-azobis (2-amidinopropane) hydrochloride are used. Etc.], inorganic peroxides (eg hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate), organic peroxides [benzoyl peroxide, di-t-butyl peroxide, cumene hydroperoxide, succinic acid peroxide Oxides and di (2-ethoxyethyl) peroxydicarbonate etc] and redox catalysts (sulfites or bisulfites of alkali metals, ammonium sulfite, ammonium bisulfite and ascorbic acid etc, reducing agents and alkali metal persulfates, Oxidation of ammonium persulfate, hydrogen peroxide and organic peroxides And the like, and the like. These catalysts may be used alone or in combination of two or more.
The amount of the radical polymerization catalyst used is 0.0005 to 5% by weight based on the total weight of the water-soluble vinyl monomer (a1), the hydrolyzable vinyl monomer (a2) and the other vinyl monomer (a3) used as needed. Preferably, it is 0.001 to 2% by weight.

  When the suspension polymerization method or the reverse phase suspension polymerization method is employed as the polymerization method, the polymerization may be carried out in the presence of a conventionally known dispersant or surfactant, if necessary. In the case of reverse phase suspension polymerization, polymerization can be carried out using a hydrocarbon solvent such as xylene, normal hexane and normal heptane which are conventionally known.

  The polymerization initiation temperature can be appropriately adjusted depending on the type of catalyst used, but is preferably 0 to 100 ° C, and more preferably 5 to 80 ° C.

  When a solvent (such as an organic solvent and water) is used for the polymerization, the solvent is preferably distilled off after the polymerization. When the solvent contains an organic solvent, the content of the organic solvent after distillation is preferably 0 to 10% by weight, more preferably 0 to 5% by weight, particularly preferably, based on the weight of the crosslinked polymer (A1). Is 0 to 3% by weight, most preferably 0 to 1% by weight. Within this range, the absorption performance is further improved.

  The water content of the water absorbing resin (A) containing the crosslinked polymer (A1) is preferably 0 to 20% by weight, more preferably 1 to 10% by weight, particularly preferably 2 based on the weight of the water absorbing resin. ~ 9 wt%, most preferably 3-8 wt%. Within this range, the absorption performance is further improved.

  The water-containing gel polymer obtained by polymerization can be shredded if necessary. The size (longest diameter) of the shredded gel is preferably 50 μm to 10 cm, more preferably 100 μm to 2 cm, and particularly preferably 1 mm to 1 cm. Within this range, the drying property in the drying step is further improved.

  The shredding can be carried out by a known method, and shredding is carried out using a general shredding device (for example, a Bex mill, a rubber chopper, a farm mill, a mincing machine, an impact crusher and a roll crusher), etc. it can.

  In addition, the content of the organic solvent and the moisture content are infrared moisture measuring devices [for example, JET400 manufactured by KETT Co., Ltd .: 120 ± 5 ° C., 30 minutes, atmospheric humidity before heating: 50 ± 10% RH, lamp specification It is determined from the weight loss of the measurement sample when heated by 100 V, 40 W]. The decimal place and the first place were rounded off, and it was set as the content and moisture content of the organic solvent.

  As a method of distilling off the solvent (including water), a method of distilling (drying) with hot air at a temperature of 80 to 230 ° C., a thin film drying method by a drum dryer etc. heated to 100 to 230 ° C. A vacuum drying method, a lyophilization method, an infrared ray drying method, a decantation and a filtration can be applied.

  The crosslinked polymer (A1) can be pulverized after drying. There is no particular limitation on the grinding method, and a common grinding device (for example, a hammer type crusher, an impact type crusher, a roll crusher, a shet type crusher, etc.) can be used. The particle size of the pulverized crosslinked polymer (A1) can be adjusted by sieving, if necessary.

  The shape of the pulverized and classified crosslinked polymer (A1) is not particularly limited, and examples thereof include irregularly crushed, scaly, pearly and rice grains.

  The pulverized and classified crosslinked polymer (A1) may be treated with a hydrophobic substance as necessary, and the method described in JP-A-2013-231199 or the like can be used.

The surface of the pulverized and classified crosslinked polymer (A1) can be crosslinked by a surface crosslinking agent.
As surface crosslinking agents, known (polyvalent glycidyl compounds described in JP-A-59-189103, polyhydric amines, polyvalent aziridine compounds, and polyvalent isocyanate compounds, etc., JP-A-58-180233 and JP-A Polyhydric alcohols disclosed in JP-A-61-16903, silane coupling agents disclosed in JP-A-61-211305 and JP-A-61-252212, alkylene carbonates described in JP-A-5-508425, The polyvalent oxazoline compounds described in JP-A-11-2405959 and the surface cross-linking agents of JP-A-51-136588 and JP-A-61-257235 can be used. A surface crosslinking agent may be used individually by 1 type, and may use 2 or more types together.

  Among these surface crosslinking agents, it is preferable to use a surface crosslinking agent containing a polyvalent glycidyl compound and / or a polyvalent metal salt from the viewpoint of economy, absorption characteristics and moisture absorption blocking property, and polyvalent glycidyl compound and polyvalent metal It is further preferable to use a metal salt in combination.

  Among polyvalent glycidyl compounds, preferred are polyglycidyl ethers of polyhydric alcohols such as ethylene glycol diglycidyl ether, glycerin triglycidyl ether and sorbitol polyglycidyl ether. The epoxy equivalent of the polyvalent glycidyl compound is preferably 60 to 600, more preferably 100 to 300, and the number of functional groups is preferably 2 to 6, more preferably 2 to 4. The epoxy equivalent means a value obtained by dividing the molecular weight of the polyvalent glycidyl compound by the number of glycidyl groups in one molecule. One of these polyvalent glycidyl compounds may be used alone, or two or more thereof may be used in combination.

  Among the polyvalent metal salts, preferable ones include inorganic acid salts of zirconium, aluminum or titanium, and as the inorganic acids forming the polyvalent metal salts, sulfuric acid, hydrochloric acid, nitric acid, hydrobromic acid, iodination Examples thereof include hydrogen acid and phosphoric acid. Examples of inorganic acid salts of zirconium include zirconium sulfate and zirconium chloride, and examples of inorganic acid salts of aluminum include aluminum sulfate, aluminum chloride, aluminum nitrate, ammonium sulfate, potassium aluminum sulfate, sodium aluminum sulfate and the like. Examples of the inorganic acid salt of titanium include titanium sulfate, titanium chloride and titanium nitrate.

  Among them, inorganic acid salts of aluminum and inorganic acid salts of titanium are preferable in view of availability and solubility, and aluminum sulfate, aluminum chloride, potassium aluminum sulfate and sodium aluminum sulfate are more preferable. Are aluminum sulfate and sodium aluminum sulfate, most preferably sodium aluminum sulfate. One of these polyvalent metal salts may be used alone, or two or more thereof may be used in combination.

  The amount of the surface crosslinking agent used is not particularly limited because it can be variously changed depending on the type of the surface crosslinking agent, the conditions to be crosslinked, the target performance, etc. From the viewpoint of absorption characteristics etc., the water soluble vinyl monomer (a1 0.001 to 3% by weight, preferably 0.005 to 2% by weight, particularly preferably 0.01 to 3% by weight, based on the total weight of the hydrolyzable vinyl monomer (a2) and the crosslinker (a4) It is 1% by weight.

  The surface crosslinking agent is used after diluting it with a solvent, if necessary. The type of solvent is not particularly limited, but polyhydric alcohols (such as ethylene glycol, propylene glycol and 1,4-butanediol) and water are suitably used, and two or more types of solvents may be used alone or in combination. You may use together.

  The apparatus used to uniformly mix the cross-linked polymer (A1) and the surface cross-linking agent may be a general mixer, for example, a cylindrical mixer, a screw mixer, a screw extruder, a turbulizer , Nauta type mixer, double arm type kneader, fluid type mixer, V type mixer, minced mixer, ribbon type mixer, fluid type mixer, air flow type mixer, rotating disc type mixer, conical blender and roll A mixer etc. are mentioned.

  The temperature at which the cross-linked polymer (A1) and the surface cross-linking agent are uniformly mixed is not particularly limited, but it is preferably 10 to 150 ° C, more preferably 20 to 100 ° C, and particularly preferably 25 to 80 ° C.

  The temperature at the time of surface crosslinking of the crosslinked polymer (A1) with the surface crosslinking agent is not particularly limited, but it is preferably 100 to 150 ° C., more preferably 110 to 145 ° C., particularly preferably 125 to 140 ° C. from the viewpoint of absorption characteristics. It is. Further, the time for surface crosslinking is preferably 5 to 60 minutes, more preferably 10 to 40 minutes, from the viewpoint of absorption characteristics.

  The particulate water-absorbent resin (A) in the present invention comprises a crosslinked polymer (A1) and is a particle having a volume average particle diameter of 10 to 60 μm. The crosslinked polymer (A1) may be used alone or in combination of two or more.

  The water-absorbent resin (A) is, if necessary, an additive (for example, known preservatives (described in JP-A 2003-225565 and JP-A 2006-131767, etc.) preservatives, fungicides, antibacterial agents, antioxidants Agents, ultraviolet light absorbers, colorants, fragrances, deodorants, liquid permeability improvers, organic fibrous materials, etc.). When these additives are contained, the content of the additive is preferably 0.001 to 10% by weight, more preferably 0.01 to 5% by weight, based on the weight of the crosslinked polymer (A1). Preferably it is 0.05 to 1 wt%, most preferably 0.1 to 0.5 wt%.

  The water absorbent resin (A) is obtained by grinding the crosslinked polymer (A1). The pulverizing method may be a general method, for example, an impact pulverizer (a pin mill, a cutter mill, a skirel mill, an ACM pulper or the like), an air pulverizer (a jet crusher or the like) or the like.

  The volume average particle diameter of the particulate water absorbent resin (A) is 10 to 60 μm, preferably 10 to 50 μm, and more preferably 10 to 40 μm. When the volume average particle diameter of the particulate water-absorbent resin (A) is less than 10 μm, the handling property is deteriorated, and when it exceeds 60 μm, the transparency is deteriorated.

  In the active energy ray-curable composition, the particulate water-absorbent resin (A) is a water-containing gel. By drying the water-containing gel by the following air-flow drier method, the original particulate water-absorbent resin (A) can be obtained.

  The volume average particle diameter of the water absorbing resin (A) is measured by dispersing (A) in anhydrous methanol and using a laser diffraction type particle size distribution measuring apparatus [Microtrac (manufactured by Nikkiso Co., Ltd.)].

  The water absorption of the water-absorbent resin (A) to pure water is preferably 50 to 800 g / g, more preferably 70 to 700 g / g, particularly preferably 80 to 600 g / g from the viewpoint of strength and flexibility of the hydrogel. It is.

The water absorption amount of the water absorbent resin (A) to pure water in the present invention is measured by the following method.
<Method of measuring water absorption>
Prepare a tea bag shaped bag made of 250 mesh nylon net, size 10 × 20 cm, heat seal width 5 mm, and pure water. After 0.1 g of the measurement sample is mixed with 20 g of water in a beaker and swollen for 10 minutes, it is put into a tea bag-like bag and immersed in pure water to dip about 15 cm from the bottom of the tea bag-like bag. After leaving for 1 hour, the tea bag-like bag is pulled up, hung vertically, drained for 15 minutes, and the weight (W ₁ ) is measured. The same operation is carried out using an empty tea bag-like bag containing no sample, the weight (W ₂ ) is measured, and the water absorption is calculated from the following equation.
Water absorption amount (g / g) = (W _1- W ₂ ) / 0.1

The monomer component (B) contained in the active energy ray-curable composition of the present invention contains a water-soluble monofunctional vinyl monomer (b1) and a bifunctional (meth) acrylate (b2) represented by the general formula (1) Do.
When (B) contains (b1), a hydrogel excellent in flexibility is obtained, and when (b2) is contained, a hydrogel excellent in flexibility and strength is obtained.

Examples of the water-soluble monofunctional vinyl monomer (b1) include the same as those exemplified as the water-soluble vinyl monomer (a1), and from the viewpoint of flexibility and strength, monoalkyl (meth) having 4 to 8 carbon atoms ) Acrylamide, dialkyl (meth) acrylamide having 5 to 8 carbon atoms, hydroxyalkyl (meth) acrylamide having 4 to 8 carbon atoms, N- (N ', N'-dialkylaminoalkyl) acrylamide having 6 to 9 carbon atoms, carbon The hydroxyalkyl (meth) acrylate and N- (meth) acryloyl morpholine of the number 5-8 are preferable. Here, for example, a monoalkyl (meth) acrylamide having 4 to 8 carbon atoms means that the number of carbon atoms constituting the monoalkyl (meth) acrylamide is 4 to 8. (B1) may be used alone or in combination of two or more.
In particular, by combining N- (meth) acryloyl morpholine with other water-soluble monofunctional vinyl monomers, a hydrogel excellent in strength and transparency can be obtained.

R ¹ and R ² in the general formula (1) each independently represent a methyl group or a hydrogen atom, and a hydrogen atom is preferable from the viewpoint of the curing rate.

  N in the general formula (1) is an integer of 4 to 60, preferably 5 to 50, more preferably 10 to 30 from the viewpoint of strength and flexibility.

  Specific examples of the bifunctional (meth) acrylate (b2) represented by the general formula (1) include polyethylene glycol (n = 4 to 60) di (meth) acrylate.

  The weight ratio of the bifunctional (meth) acrylate (b2) represented by the general formula (1) to the water soluble monofunctional vinyl monomer (b1) is a water soluble monofunctional vinyl monomer (b1) from the viewpoint of strength and flexibility. It is preferable that it is 0.1 to 10 weight% based on the weight of).

  As the photo radical polymerization initiator (C), 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, phenyl (2,4,6-) Lithium trimethyl benzoyl) phosphinate, α-ketoglutaric acid and the like can be mentioned, and from the viewpoint of curability, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1- is particularly preferable. Propane-1-one. (C) may be used alone or in combination of two or more.

  The active energy ray-curable composition of the present invention may further contain, according to the purpose of use, a polymerization inhibitor, a tackifier, an antifoamer, a thixotropic agent, a slip agent, a flame retardant, an antistatic agent, an antioxidant And UV absorbers can be contained.

  The viscosity at 25 ° C. of the active energy ray-curable composition of the present invention is preferably 10 to 10000 mPa · s, more preferably 50 to 5000 mPa · s, from the viewpoint of handleability. The viscosity in the present invention is measured using a viscosity measuring apparatus [“Bisco Elite B type” manufactured by FUNGILAB].

  The ratio of the weight of the water absorbent resin (A) to the total weight of the water absorbent resin (A) and the monomer component (B) is preferably 0.2 to 5 weight from the viewpoint of handleability and strength and flexibility of the hydrogel. %, More preferably 0.5 to 3% by weight.

  The ratio of the total weight of the water absorbent resin (A) and the monomer component (B) to the total weight of the water absorbent resin (A), the monomer component (B) and water is preferably from the viewpoint of strength and flexibility of the hydrogel. It is 5 to 60% by weight, more preferably 10 to 55% by weight.

  The content of the photoradical polymerization initiator (C) is preferably 0.1 to 10% by weight based on the weight of the monomer component (B) from the viewpoint of curability.

The content of the water absorbing resin (A) is preferably 0.1 to 1.5 weight based on the weight of the active energy ray curable composition from the viewpoint of composition handling and strength and flexibility of the hydrogel. %.
The content of the monomer component (B) is preferably 19 to 60% by weight based on the weight of the active energy ray-curable composition from the viewpoint of strength and flexibility of the hydrogel.
The content of the photoradical polymerization initiator (C) is preferably 0.01 to 1.0% by weight based on the weight of the active energy ray-curable composition from the viewpoint of curability.
The content of water is preferably 39 to 80% by weight based on the weight of the active energy ray-curable composition from the viewpoint of handleability and strength and flexibility of the hydrogel.

  The active energy ray-curable composition of the present invention can be obtained, for example, by mixing each of the above components with a known mixing device such as a planetary mixer.

  The hydrogel of the present invention is obtained by curing the active energy ray-curable composition of the present invention using an active energy ray.

  The active energy ray may, for example, be ultraviolet ray, electron beam, X-ray, infrared ray or visible ray, and ultraviolet ray is preferable from the viewpoint of curing and resin deterioration.

In the case of curing the active energy ray curable composition of the present invention with ultraviolet light, various ultraviolet light irradiation devices [for example, ultraviolet light irradiation devices [model number "VPS / I600", manufactured by Fusion UV Systems Ltd.] can be used.
Examples of the lamp to be used include a high pressure mercury lamp and a metal halide lamp. The dose of ultraviolet rays is preferably from the viewpoint of the strength and flexibility of the cured as well as the hydrogel 10 to 10000 mJ / cm ^2, more preferably from 100~5000mJ / cm ^2.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.

<Production Example 1>
Acrylic acid (a1-1) {Mitsubishi Chemical Co., Ltd., purity 100% by weight, solubility in water: miscibility} 131 parts by weight, crosslinker (a4-1) {pentaerythritol triallyl ether, diso-made} 0.44 parts by weight and 362 parts by weight of deionized water were kept at 3 ° C. with stirring and mixing. After nitrogen is introduced into this mixture to make the amount of dissolved oxygen 1 ppm or less, 0.5 parts by weight of a 1% by weight aqueous solution of hydrogen peroxide, 1 part by weight of a 2% by weight aqueous solution of ascorbic acid and 2% by weight of 2,2 ' 0.1 part by weight of an aqueous solution of azobisamidinopropane dihydrochloride was added and mixed to initiate polymerization. After the temperature of the mixture reached 80 ° C., a hydrogel was obtained by polymerizing at 80 ± 2 ° C. for about 5 hours.

  Next, while the water-containing gel was shredded with a mincing machine (12 VR-400 K manufactured by ROYAL), 162 parts by weight of a 45 wt% aqueous sodium hydroxide solution was added and mixed and neutralized to obtain a neutralized gel. Furthermore, the neutralized water-containing gel was dried by a ventilated drier {200 ° C., wind speed 2 m / sec} to obtain a dried product. The dried product was pulverized with a juicer mixer (OSTERIZER BLENDER manufactured by Oster) and sieved to adjust to a particle diameter range of 150 to 710 μm, thereby obtaining resin particles containing crosslinked polymer particles.

  Next, while stirring 100 parts by weight of the obtained resin particles at a high speed (high speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), 0.08 parts by weight ethylene glycol diglycidyl ether as a first cross-linking agent A mixed solution of 0.9 parts by weight of propylene glycol as a solvent and 1.4 parts by weight of water is added and uniformly mixed, heated at 130 ° C. for 30 minutes, cooled to room temperature, and further stirred at high speed A mixed solution of 1 part by weight of ethylene carbonate as a second surface cross-linking agent and 5 parts by weight of water as a solvent was added and uniformly mixed while (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm) After heating at 170 ° C for 30 minutes, the resulting dried product is coarsely crushed with a household cooking mixer, and then pulverized with a pin mill. To, and further classified (using sieve passed product of mesh 45) to obtain a cross-linked polymer (A1-1) comprising the particulate absorbent resin (A-1). The water content of (A-1) was 4% by weight, the volume average particle diameter was 30 μm, and the water absorption to pure water was 550 g / g.

<Production Example 2>
A particulate water absorbent resin (A-2) was obtained in the same manner as in Production Example 1 except for the classification operation (using a pass product of a sieve with an opening of 26 μm). The water content of (A-2) was 4% by weight, the volume average particle diameter was 15 μm, and the water absorption amount with respect to pure water was 650 g / g.

<Production Example 3>
A particulate water absorbent resin (A-3) was obtained in the same manner as in Production Example 1 except for the classification operation (using a pass product of a sieve with an opening of 62 μm). The water content of (A-3) was 4% by weight, the volume average particle diameter was 50 μm, and the water absorption to pure water was 350 g / g.

Production Example 4
A particulate water absorbent resin (A-4) was obtained in the same manner as in Production Example 1 except that the amount of the crosslinking agent was changed from 0.44 part to 0.20 part. The water content of (A-4) was 4% by weight, the volume average particle diameter was 30 μm, and the water absorption to pure water was 750 g / g.

<Production Example 5>
A particulate water absorbent resin (A-5) was obtained in the same manner as in Production Example 3 except that the amount of the crosslinking agent was changed from 0.44 part to 0.66 part. The water content of (A-5) was 4% by weight, the volume average particle diameter was 50 μm, and the water absorption to pure water was 100 g / g.

<Comparative Production Example 1>
207 parts by weight of sodium 2-acrylamido-2-methylpropane sulfonate, 84 parts by weight of sodium hydrogencarbonate, 6 parts by weight of methylene bisacrylamide, 2,2-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] An aqueous solution was prepared by stirring and mixing 0.6 parts by weight of tetrahydrate and 720 parts by weight of ion exchange water.
A 10% by weight aqueous solution of 2,2-azobis (2-amidinopropane) hydrochloride [trade name "V-50" manufactured by Wako Pure Chemical Industries, Ltd.] 1.25 parts by weight is added, and the aqueous solution is started until the polymerization starts Continued nitrogen bubbling inside. After confirming that the polymerization started and the viscosity in the system started to rise, the nitrogen aeration was stopped and then polymerization was carried out for 6 hours to obtain a water-containing gel. The highest temperature reached of the reaction system was 75.degree. The water-containing gel is laminated on a SUS screen of 850 μm mesh size to a thickness of 5 cm, and heated air at 120 ° C. using a small air-permeable drier [model number “HAP2031F”, manufactured by HAKKO Co., Ltd.]. The water-containing gel was dried by permeating the water-containing gel for 1 hour.
The dried product was roughly pulverized by a household cooking mixer, then finely pulverized by a pin mill, and further classified to obtain a particulate water absorbent resin (A'-1) for comparison. The water content of (A′-1) was 4% by weight, the volume average particle diameter was 75 μm, and the water absorption to pure water was 100 g / g.
<Comparative Production Example 2>
Acrylic acid (a1-1) {Mitsubishi Chemical Co., Ltd., purity 100% by weight, solubility in water: miscibility} 131 parts by weight, crosslinker (a4-1) {pentaerythritol triallyl ether, diso-made} 0.44 parts by weight and 362 parts by weight of deionized water were kept at 3 ° C. with stirring and mixing. After nitrogen is introduced into this mixture to make the amount of dissolved oxygen 1 ppm or less, 0.5 parts by weight of a 1% by weight aqueous solution of hydrogen peroxide, 1 part by weight of a 2% by weight aqueous solution of ascorbic acid and 2% by weight of 2,2 ' 0.1 part by weight of an aqueous solution of azobisamidinopropane dihydrochloride was added and mixed to initiate polymerization. After the temperature of the mixture reached 80 ° C., a hydrogel was obtained by polymerizing at 80 ± 2 ° C. for about 5 hours.

  Next, while the water-containing gel was shredded with a mincing machine (12 VR-400 K manufactured by ROYAL), 162 parts by weight of a 45 wt% aqueous sodium hydroxide solution was added and mixed and neutralized to obtain a neutralized gel. Furthermore, the neutralized water-containing gel was dried by a ventilated drier {200 ° C., wind speed 2 m / sec} to obtain a dried product. The dried product was pulverized with a juicer mixer (OSTERIZER BLENDER manufactured by Oster) and sieved to adjust to a particle diameter range of 150 to 710 μm, thereby obtaining resin particles containing crosslinked polymer particles.

  Next, while stirring 100 parts by weight of the obtained resin particles at a high speed (high speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm), 0.08 parts by weight ethylene glycol diglycidyl ether as a first cross-linking agent A mixed solution of 0.9 parts by weight of propylene glycol as a solvent and 1.4 parts by weight of water is added and uniformly mixed, heated at 130 ° C. for 30 minutes, cooled to room temperature, and further stirred at high speed A mixed solution of 1 part by weight of ethylene carbonate as a second surface cross-linking agent and 5 parts by weight of water as a solvent was added and uniformly mixed while (high-speed stirring turbulizer manufactured by Hosokawa Micron: rotation speed 2000 rpm) After heating at 170 ° C. for 30 minutes, the resulting dried product is roughly crushed by a household cooking mixer to obtain a particulate absorbent resin. A'-2) was obtained. The water content of (A′-2) was 4% by weight, the volume average particle diameter was 120 μm, and the water absorption amount to pure water was 120 g / g.

Examples 1 to 16 and Comparative Examples 1 to 3
According to the compounding amounts (parts by weight) of Table 1, the water absorbent resin (A), the monomer component (B), the photo radical polymerization initiator (C) and water are charged in a glass container and stirred until uniform Active energy ray curable compositions of Examples 1 to 16 and Comparative Examples 1 to 3 were obtained.

The details of the raw materials represented by symbols in Table 1 are as follows.
(B1-1): DMAA [Dimethylacrylamide: manufactured by KJ Chemicals, Ltd., solubility in water: miscibility]
(B1-2): DEAA [diethyl acrylamide: manufactured by KJ Chemicals, solubility in water: miscibility]
(B1-3): HEA [2-hydroxyethyl acrylate: Osaka Organic Chemical Industry Ltd., water solubility: miscibility]
(B1-4): DMAPAA [Dimethylaminopropyl acrylamide: manufactured by KJ Chemicals, solubility in water: miscibility]
(B1-5): HEAA [hydroxyethylacrylamide: manufactured by KJ Chemicals Ltd., solubility in water: miscibility]
(B1-6): ACMO [acryloyl morpholine: manufactured by KJ Chemicals, solubility in water: miscibility]
(B2-1): NK ester A-1000 [polyethylene glycol # 1000 diacrylate: manufactured by Shin-Nakamura Kogyo Co., Ltd .: n = 23 in general formula (1)]
(B2-2): NK ester A-600 [polyethylene glycol # 600 diacrylate: manufactured by Shin-Nakamura Kogyo Co., Ltd .: n = 14 in the general formula (1)]
(B2-3): NK ester A-200 [polyethylene glycol # 200 diacrylate: manufactured by Shin-Nakamura Kogyo Co., Ltd .: n = 5 in the general formula (1)]
(B2'-1): MBAA [methylene bis acrylamide: manufactured by Tokyo Chemical Industry Co., Ltd.]
(B2'-2): DEGDA [diethylene glycol diacrylate: manufactured by Hitachi Chemical Co., Ltd.]
(C-1): Irgacure 2959 {1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one: manufactured by BASF Corp.}
(C-2): Irgacure 500 [eutectic mixture of 1-hydroxy-cyclohexyl-phenyl-ketone and benzophenone: made by BASF Ltd.]
(C-3): α-ketoglutaric acid (manufactured by Tokyo Chemical Industry Co., Ltd.)

With respect to the obtained active energy ray-curable composition, the viscosity, the required exposure amount, the transparency and the tensile strength and elongation results of the hydrogel measured or evaluated by the following measurement method or evaluation method are shown in Table 1.
[Performance evaluation method]
(1) Viscosity The viscosity at 25 ° C. immediately after the formulation of the active energy ray-curable composition was measured using a viscosity measuring apparatus [“Biscoelite B type” manufactured by FUNGILAB].
(2) Necessary exposure amount The active energy ray curable composition is applied to a glass plate so that the cured film thickness is 3 mm, and the light of an ultra-high pressure mercury lamp is irradiated in the air atmosphere to obtain the surface of the cured product The exposure amount was changed while repeatedly checking the presence or absence of fluidity with a spatula, and the exposure amount at the point where the fluidity was lost was measured.
(3) Transparency (haze)
The active energy ray-curable composition was applied to a glass plate to a cured film thickness of 3 mm, and a test plate was produced by irradiating 3000 mJ / cm ² of light of an ultra-high pressure mercury lamp in an air atmosphere.
The haze of the obtained test plate was measured using a total light transmittance measurement device [trade name "haze-gard dual" BYK gardner Co., Ltd.] according to JIS K 7105. The smaller the haze, the better the transparency.
(4) Tensile strength and elongation Silicone rubber JIS K 6251 tensile test specimen Dumbbell No. 1 mold cast active energy ray curable composition so that the cured film thickness becomes 2 mm, the light of the ultra high pressure mercury lamp is 3000 mJ Irradiated at / cm ² to obtain test pieces for tensile strength and elongation test.
Mark lines were attached to the center of JIS K 6251 tensile test specimen dumbbell No. 1 at intervals of 20 mm. The film thickness adopted the minimum of five places between marked lines. The sample was attached to an autograph at 25 ° C. and pulled at a speed of 200 mm / min to determine the maximum strength and the maximum elongation until the test piece was broken.

The active energy ray-curable composition of the present invention has low viscosity and good handling properties, and can form a hydrogel that can be cured with a small amount of active energy ray irradiation. It is applicable to products in a wide range of fields such as industrial materials and biosubstitutable materials.

Claims (6)

Water-absorbing property comprising a water-soluble vinyl monomer (a1) and / or a vinyl monomer (a2) to be a water-soluble vinyl monomer (a1) by hydrolysis and a crosslinked polymer (A1) containing a crosslinking agent (a4) as an essential constituent unit A water-absorbent resin (A) which is a resin and is particulate with a volume average particle diameter of 10 to 60 μm, and a bifunctional (meth) represented by a water-soluble monofunctional vinyl monomer (b1) and the general formula (1) The active energy ray curable composition formed by mixing the monomer component (B) containing an acrylate (b2), a radical photopolymerization initiator (C), and water.

[In Formula, R < ¹ > and R < ² > respectively independently represent a methyl group or a hydrogen atom, n represents the integer of 4-60. ]   The active energy ray curable composition according to claim 1, wherein the water absorption amount of the water absorbing resin (A) to pure water is 50 to 800 g / g.   The water-soluble monofunctional vinyl monomer (b1) is a monoalkyl (meth) acrylamide having 4 to 8 carbon atoms, a dialkyl (meth) acrylamide having 5 to 8 carbon atoms, a hydroxyalkyl (meth) acrylamide having 4 to 8 carbon atoms, carbon At least one selected from the group consisting of N- (N ', N'-dialkylaminoalkyl) acrylamides having a number of 9 to 9, hydroxyalkyl (meth) acrylates having 5 to 8 carbon atoms and N- (meth) acryloyl morpholine The active energy ray-curable composition according to claim 1 or 2, which is a monomer.   The ratio of the weight of the water absorbent resin (A) to the total weight of the water absorbent resin (A) and the monomer component (B) is 0.2 to 5% by weight. Active energy ray curable composition.   The ratio of the total weight of the water absorbent resin (A) and the monomer component (B) to the total weight of the water absorbent resin (A), the monomer component (B) and the water is 5 to 60% by weight. The active energy ray-curable composition according to any one of Items 1 to 4. A hydrogel obtained by curing the active energy ray-curable composition according to any one of claims 1 to 5.