JPH1135632A - Liquid-absorbing resin and middle polar solvent-containing gel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject resin capable of absorbing and retaining a middle polar solvent without absorbing water and suitably usable for sustained release substrate, etc., by polymerizing a monomer component containing a specific (meth)acrylate-based monomer at a specific ratio. SOLUTION: This absorbing resin is obtained by polymerizing a monomer component containing a monomer composed of at least one kind of compound selected from a group comprising an alkoxyalkyl (meth)acryate and an phenoxyalkyl (meth)acrylate, preferably a monomer of the formula (R1 is H or methyl; R2 is methyl, ethyl, butyl, propyl or phenyl) in an amount of >=85 wt.%. The monomer further contains preferably a crosslinkable monomer for forming three-dimensional crosslinking structure and the crosslinkable monomer is preferably contained in an amount of 0.001-5 mol.% based on the monomer component. Thereby, the middle polar solvent can readily be recovered by absorption and moisture absorption in storing is suppressed, because the resin does not absorb water and storage under dried circumstance is not required.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for recovering the above-mentioned solvent and the like by absorbing and retaining a medium-polar solvent and not absorbing water, and also by controlling the release of a sustained-release substrate and a drug by retaining the above-mentioned solvent. The present invention relates to a liquid-absorbent resin and a gel containing a medium-polarity solvent which are suitably used for a liquid film such as a carrier substrate, a battery separator, and a separation membrane.

[0002]

2. Description of the Related Art Conventionally, when a medium-polar solvent such as propylene carbonate leaks, a non-woven fabric of polyethylene or polypropylene is used to recover the medium-polar solvent.
A method was considered in which the medium polar solvent was absorbed by the nonwoven fabric and the medium polarity solvent was wiped off.

[0003] However, in the above method, when a medium-polar solvent is absorbed in an amount more than twice the dry weight of the non-woven fabric, the non-woven fabric absorbing the medium-polar solvent is difficult to handle due to dripping, and it takes time to recover the medium-polar solvent. Has a problem.

[0004] In addition, in order to impart a sustained-release property to a drug such as an insecticide soluble in a medium-polar solvent with the above-mentioned medium-polar solvent and impart the drug with sustained release, for example, it is used by penetrating the nonwoven fabric. On the other hand, the non-woven fabric has a problem in that the holding amount of the medium-polar solvent is small, so that a long-term sustained release property is required to increase the size.

In order to simplify the recovery of the medium-polar solvent and to increase the amount of the medium-polar solvent retained, it has been considered to use a liquid-absorbing resin that absorbs the medium-polar solvent. As such a liquid-absorbing resin, JP-A-8-2
A crosslinked product disclosed in 43377 is known.

The above-mentioned crosslinked product is mainly composed of N-vinylacetamide and a polymerizable monomer having a COOM group (wherein M represents a hydrogen atom, an alkali metal salt or an ammonium salt). It comprises 0.5 to 30 parts by weight of an acetamide copolymer (component A) and 0.01 to 20 parts by weight of a crosslinking agent (component B) which reacts with and crosslinks the COOM group of component A.

[0007]

However, the cross-linked product described in the above-mentioned conventional publication has a hygroscopic property because it does not inhibit water absorption at all, and when it absorbs moisture, it absorbs a medium-polar solvent by the absorbed amount. Performance decreases. For this reason, in order to maintain the predetermined liquid absorption performance, it is necessary to store the crosslinked product in a dry state, and there is a problem that it takes time to handle the crosslinked product.

[0008]

In order to solve the above-mentioned problems, the liquid-absorbent resin according to the first aspect of the present invention is selected from the group consisting of alkoxyalkyl (meth) acrylate and phenoxyalkyl (meth) acrylate. A monomer component containing at least 85% by weight of at least one monomer (A).

The alkyl group in the alkoxyalkyl (meth) acrylate and phenoxyalkyl (meth) acrylate is preferably a straight-chain alkyl group having 1 to 5 carbon atoms, particularly preferably an ethyl group.

The liquid-absorbent resin according to claim 2 of the present invention has the general formula (1)

[0011]

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(In the above formula, R ₁ represents hydrogen or a methyl group, and R ₂ represents a methyl group, an ethyl group, a butyl group, a propyl group or a phenyl group.) 85% by weight of the monomer (A)
It is characterized by being obtained by polymerizing the monomer components contained above.

The liquid absorbing resin according to the third aspect of the present invention is further characterized in that the monomer component has a crosslinkable monomer for forming a three-dimensional crosslinked structure.

The liquid-absorbent resin according to claim 4 of the present invention is further characterized in that the crosslinkable monomer is a crosslinkable unit in the crosslinkable monomer based on the total amount of the monomer units of the monomer component. Is 0.0
It is characterized in that it is contained in an amount of from 0.01 to 5 mol%.

According to the above structure, for example, by having an alkoxyethyl group and / or a phenoxyethyl group in the side chain, the affinity for a medium-polar solvent is high, and
Since the affinity for water is low, each medium-polar solvent having a solubility parameter of 10 to 15 can be widely absorbed and has hydrophobicity that does not absorb water.

In particular, the monomer component contains a crosslinkable monomer,
Further, the crosslinkable monomer is a bifunctional group-containing monomer,
By being contained in an amount of 0.001 to 5 mol% based on the monomer component, the absorption ratio of the medium-polar solvent can be improved, and the liquid-absorbing resin having absorbed the medium-polar solvent is excellent. Flexibility can be provided.

According to a fifth aspect of the present invention, there is provided a gel containing a medium polar solvent, wherein the medium polar solvent having a solubility parameter (SP value) of 10 to 15 is absorptive to the liquid absorbent resin according to the third or fourth aspect. It is characterized by being held by swelling of the resin.

According to the above configuration, the liquid-absorbent resin retains the medium-polar solvent by swelling. Therefore, the medium-polar solvent having a solubility parameter (SP value) of 10 to 15 per 1 part by weight of the liquid-absorbent resin is used. As much as 3 to 20 parts by weight.

The gel containing a medium polar solvent according to claim 6 of the present invention is obtained by polymerizing the monomer component according to claim 3 or 4 in the presence of a medium polar solvent. It is characterized by having a liquid absorbing resin to hold.

According to the above constitution, the alkoxyalkyl (meth) acrylate or phenoxyalkyl (meth) acrylate as the monomer (A) is not allowed to react with the alkoxyalkyl group or phenoxyalkyl group, which is a side chain of the phenoxyalkyl (meth) acrylate, with respect to a medium polar solvent. Since it has an affinity, when the monomer component is polymerized in the presence of a medium polar solvent, the medium polarity solvent intervenes as a spacer between the monomers (A).

According to the above configuration, a space in the crosslinked liquid-absorbent resin in which the medium-polarity solvent is absorbed and held can be further secured, so that the liquid-absorbing performance of the medium-polarity solvent can be further improved. Can be.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below. The liquid-absorbent resin of the present invention is a monomer component containing at least 85% by weight of at least one monomer (A) selected from the group consisting of alkoxyethyl (meth) acrylate and phenoxyethyl (meth) acrylate. Is polymerized, for example, in the presence of a radical polymerization initiator.

In the above liquid-absorbent resin, it is preferable that the polymer obtained by polymerizing the monomer component has a three-dimensional crosslinked structure in order to more stably absorb and retain the medium polar solvent. In order to provide such a three-dimensional crosslinked structure to the polymer,
The monomer component includes at least one monomer (A) selected from the group consisting of an alkoxyalkyl (meth) acrylate having one polymerizable unsaturated group in the molecule and a phenoxyalkyl (meth) acrylate. And a crosslinkable monomer (B) having at least two polymerizable unsaturated groups in the molecule or having a functional group for crosslinking separately. It is preferred to include.

The gel containing a medium polar solvent according to the present invention has a solubility parameter (SP value) of 10 to 15
Is held by the swelling of the liquid absorbing resin. Further, the gel containing the medium polar solvent is preferably a gel obtained by polymerizing the monomer component in the presence of the medium polar solvent.

The above monomer (A) and crosslinkable monomer (B)
And the proportion of the monomer (A) 9
5 to 99.999 mol%, crosslinkable monomer (B) 0.00
1 to 5 mol% (however, the total of the monomer (A) and the cross-linkable monomer (B) is preferably 100 mol%). ,
More preferably, it is 0.005 to 2 mol%, further preferably 0.01 to 1 mol%.

The crosslinkable monomer (B) is a monomer having at least two polymerizable unsaturated monomers in the molecule, for example, ethylene glycol di (meth) acrylate, diethylene glycol Di (meth) acrylate, polyethylene glycol di (meth) acrylate, polyethylene glycol-polypropylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) ) Acrylate, neopentyl glycol di (meth)
Acrylate, 1,6-hexanediol di (meth) acrylate, N, N'-methylenebisacrylamide, N, N'-propylenebisacrylamide, glycerin tri (meth)
Esterification of alkylene oxide adduct of acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, polyhydric alcohol (eg, glycerin, trimethylolpropanetetramethylolmethane) with (meth) acrylic acid The obtained polyfunctional (meth) acrylate or divinylbenzene is preferable, and one or more of these crosslinkable monomers can be used.

Further, as the crosslinkable monomer (B), a condensable functional group (X) that forms a chemical bond by condensing with a condensable functional group (Y) of a crosslinker described below. May be a compound having the same. Examples of such a condensable functional group (X) include a carboxyl group, a hydroxyl group, a mercapto group, a nitrile group, an amino group, an amide group, an isocyanate group, an epoxy group, and a polymerizable unsaturated group of an acid anhydride. .

Specific examples of such a crosslinkable monomer (B) include a vinyl monomer having a carboxyl group, a vinyl monomer having a hydroxyl group, a vinyl monomer having a mercapto group, Vinyl monomer having a nitrile group, vinyl monomer having an amino group, vinyl monomer having an amide group, vinyl monomer having an isocyanate group, vinyl monomer having an epoxy group And an acid anhydride having a polymerizable unsaturated group. One or more of these monomers can be used.

The crosslinking agent has at least two condensable functional groups (Y) in the molecule, and is appropriately selected according to the condensable functional groups (X) contained in the polymer.
Examples of such a crosslinking agent include a condensable functional group (X)
When the compound is a carboxyl group, a mercapto group, a nitrile group, or an epoxy group, a phenol resin such as dimethylol phenol or polymethylol phenol, which can be condensed.

As another example of the crosslinking agent, an amino compound such as melamine, benzoguanamine or urea, which can be condensed when the condensable functional group (X) is a carboxyl group or a hydroxyl group, and formaldehyde or alcohol are used. An addition-condensed amino resin may be used.

As still another example of the crosslinking agent, hexamethylenediamine, diethylenetriamine and tetraethylenepentamine which can be condensed when the condensable functional group (X) is a carboxyl group, an isocyanate group or an epoxy group. And polyvalent amino compounds.

As still another example of the crosslinking agent, the condensable functional group (X) may be a carboxyl group, a hydroxyl group,
Hexamethylene diisocyanate, isophorone diisocyanate, p which can be condensed when it is a mercapto group, isocyanate group, amide group, amino group, epoxy group
Phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate,
Examples thereof include 1,5-naphthalenediisocyanate and isocyanate compounds such as blocked isocyanate obtained by condensing these isocyanates with methanol, phenol, or the like.

Still another example of the above-mentioned cross-linking agent is malonic acid, succinic acid, adipic acid, phthalic acid, terephthalic acid or the like which can be condensed when the condensable functional group (X) is an isocyanate group or an epoxy group. And polycarboxylic acids such as acids.

Further examples of the crosslinking agent include phthalic anhydride and pyromellitic anhydride, which can be condensed when the condensable functional group (X) is a hydroxyl group, an isocyanate group or an epoxy group. Acid anhydrides such as benzophenonetetracarboxylic acid anhydride are exemplified.

Still another example of the crosslinking agent is an aldehyde compound such as glyoxal or terephthalaldehyde which can be condensed when the condensable functional group (X) is a hydroxyl group, a mercapto group, an amino group or an amide group. Is mentioned.

Still another example of the crosslinking agent is ethylene glycol, diethylene glycol, propylene glycol or hexanediol which can be condensed when the condensable functional group (X) is a hydroxyl group, an isocyanate group or an epoxy group. And other polyhydric alcohols.

As still another example of the crosslinking agent, the condensable functional group (X) may be a carboxyl group, a hydroxyl group,
Epoxy compounds such as toluene glycidyl ether, hexamethylene glycidyl ether, bisphenol A diglycidyl ether, and polypropylene glycol diglycidyl ether, which can be condensed when they are a mercapto group or an isocyanate group, are exemplified.

The combination of each compound as such a crosslinking agent is appropriately determined depending on the type of the condensable functional group (X) contained in the polymer, and one or more of these compounds are used.

Among these, a particularly preferred combination of the condensable functional group (X) and the condensable functional group (Y) of the crosslinking agent is
At least one functional group selected from the group consisting of a carboxyl group, a hydroxyl group, a mercapto group, an amino group and an amide group, and at least one functional group selected from the group consisting of an isocyanate group, an epoxy group, and a carboxylic anhydride group; It is a combination of

The ratio of the crosslinking agent used to the polymer to be crosslinked is determined by the number of moles of the condensable functional group (X), which is a constituent unit of the polymer, and the condensable functional group (Y) of the crosslinking agent.
And the number of moles of the condensable functional group (Y) is 0.1 to 10 per mole of the condensable functional group (X).
Is preferably within the range.

When the number of moles of the condensable functional group (Y) is less than 0.1 based on 1 mole of the condensable functional group (X), the crosslinked polymer cannot be sufficiently crosslinked and has a low strength. It is not preferable because only the above may be obtained. On the other hand, when it exceeds 10, it is not preferable because a crosslinked polymer having excellent properties such as retaining a large amount of a medium polar solvent may not be formed.

The monomer component may further contain another monomer (c) having at least one polymerizable unsaturated group in the molecule. Such a monomer (c)
As unsaturated carboxylic acid ester, (meth) acrylamide having a hydrocarbon group, α-olefin, alicyclic vinyl compound, allyl ether having an aliphatic hydrocarbon group, vinyl ester having an aliphatic hydrocarbon group, and fatty acid Examples thereof include vinyl ethers having an aromatic hydrocarbon group and aromatic vinyl compounds, and one or more of these monomers can be used.

As the unsaturated carboxylic acid ester, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, iso-butyl (meth) acrylate, t-butyl (meth) acrylate , 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, phenyl (meth) acrylate, octylphenyl (meth) acrylate, nonylphenyl (meth) acrylate, di Nonylphenyl (meth) acrylate, cyclohexyl (meth) acrylate, menthyl (meth)
Examples include acrylate, isobonyl (meth) acrylate, dibutyl (meth) acrylate, dibutyl maleate, didodecyl maleate, dodecyl rotonate, didodecyl itaconate, and the like.

Examples of the (meth) acrylamide having a hydrocarbon group include (di) butyl (meth) acrylamide,
(Di) dodecyl (meth) acrylamide, (di) stearyl (meth) acrylamide, (di) butylphenyl (meth) acrylamide, (di) octylphenyl (meth) acrylamide and the like.

As the α-olefin, 1-hexene, 1-hexene
Octene, isooctene, 1-nonene, 1-decene and the like can be mentioned. Examples of the alicyclic vinyl compound include vinylcyclohexane and the like. Examples of the allyl ether having an aliphatic hydrocarbon group include dodecyl allyl ether.

Examples of the vinyl ester having an aliphatic hydrocarbon group include vinyl caproate, vinyl laurate, vinyl palmitate, vinyl stearylate and the like.
Examples of the vinyl ether having an aliphatic hydrocarbon group include butyl vinyl ether and dodecyl vinyl ether. Examples of the aromatic vinyl compound include styrene, t-butylstyrene, octylstyrene, and the like.

Examples of the radical polymerization initiator include oil-soluble organic peroxides such as benzoyl peroxide, lauroyl peroxide and cumene hydroperoxide; 2,2'-azobisisobutyronitrile; An azo compound such as 2,2'-azobisdimethylvaleronitrile can be mentioned. Further, a photopolymerizable material can also be used.

The above radical polymerization initiator can be generally used in the range of 0.1 to 5% by weight based on the monomer component. The polymerization temperature is a temperature at which the medium-polar solvent used can maintain a liquid state, depending on the melting point of the medium-polar solvent, the type of the monomer component, and the type of the polymerization initiator, and is 0 to 150 ° C.
Can be appropriately selected within the range, but more preferably from 0 to 80 ° C.

As a method for producing the liquid-absorbent resin of the present invention, the monomer components are mixed with each other in an aqueous solvent, mixed and suspended, and suspended in the presence of the above-mentioned radical polymerization initiator. A method of suspension polymerization (suspension polymerization in water) can also be used.

As described above, when, for example, suspension polymerization is used in an aqueous solvent such as water, the suspension polymerization is carried out by adding the above-mentioned monomer component to a protective colloid agent or a surfactant in an aqueous medium such as water. Is dissolved in, for example, an aqueous surfactant solution in the form of suspended particles and polymerized using, for example, a radical polymerization initiator. In addition, if necessary, the monomer component may be dissolved in a water-insoluble organic solvent in advance, and then the solution may be subjected to suspension polymerization in an aqueous solvent.

Examples of the protective colloid agent include polyvinyl alcohol, hydroxyethyl cellulose, gelatin and the like. Examples of the surfactant include sodium alkyl sulfonate, sodium alkyl benzene sulfonate, polyoxyethylene alkyl ether, and fatty acid. Soaps and the like can be mentioned.

The liquid-absorbent resin and the medium-polar solvent-containing gel of the present invention absorb and retain a large amount of the medium-polar solvent and do not absorb water. It is suitable for use as a sustained-release base material, a drug-carrying base material, a liquid membrane such as a battery separator, a separation membrane, etc. by retaining the above-mentioned medium-polar solvent in which the electrolyte is dissolved.

By the way, as a polymer using an alkoxyalkyl (meth) acrylate as a monomer component,
For example, a polymer described in JP-A-7-118144 can be mentioned. The polymer is intended to absorb water by using an alkoxyalkyl (meth) acrylate in an amount of 75% by weight or less. No disclosure or suggestion is made regarding absorption and retention of polar solvents, which is irrelevant to the present invention.

In recent years, lithium ion secondary batteries have been developed as secondary batteries having high capacity, high output, and high safety. The lithium ion secondary battery,
A positive electrode, a negative electrode, a separator for separating the positive electrode and the negative electrode,
An organic non-aqueous electrolyte in which a lithium salt of a supporting electrolyte is dissolved is housed in a metal case to form a sealed structure.

As the positive electrode, lithium cobaltate, lithium nickelate, spinel-type lithium manganate, or a composite oxide thereof is mainly used. As the negative electrode, a carbon material capable of occluding and releasing lithium ions, for example, graphitized carbon having high crystallinity or coke having low crystallinity is used.

The solvent of the organic non-aqueous electrolyte has a high dielectric constant, a suitable solvent affinity for lithium ions, and a low viscosity which does not hinder the movement of ions in order to dissolve the lithium salt as a supporting electrolyte. Organic solvents are preferred, for example, ethylene carbonate, propylene carbonate,
γ-butyrolactone, dimethyl sulfoxide, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dimethoxyethane, or mixtures thereof have been used.

The supporting electrolyte may be any as long as it can impart ionic conductivity to the electrolyte. For example, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, arsenic hexafluoride, etc. Lithium oxide.

The separator has a strength to separate the positive electrode and the negative electrode while maintaining a small gap between them, in order to maintain a high capacity capable of discharging with a large current. For example, a microporous membrane made of polyethylene or polypropylene that retains the electrolyte without being corroded is used.

However, in the above-mentioned conventional separator, it is necessary to set the fiber density of the nonwoven fabric to be large in order to secure the strength for maintaining the interval. Therefore, in the separator holding the electrolyte, the content of the electrolyte is small. ,
There is a problem that it is limited to exhibit excellent output characteristics such as discharge with a large current.

However, in the liquid absorbing resin and the gel containing a medium polar solvent of the present invention, the medium polarity solvent can be retained by swelling, so that the content of the electrolyte can be set larger than before, and excellent output characteristics such as discharge at a large current can be obtained. Can be demonstrated.

In particular, when the liquid-absorbent resin is polymerized in the presence of a medium-polarity solvent, the liquid-absorbent resin can hold the medium-polarity solvent more and more reliably, and Content can be set higher than before,
In addition, since it is excellent in strength and the interval between the positive electrode and the negative electrode can be set smaller than before, excellent output characteristics such as discharge at a large current can be further exhibited.

Further, in the above-mentioned conventional separator, a strip-shaped positive electrode plate and a negative electrode plate are spirally wound through the separator to form a metal so that a large current can be discharged by enlarging the working area of the electrode. When housed in a container, the above separator lacks flexibility, so that wrinkles are likely to occur particularly at a location where the curvature on the central axis side is large, the distance between the positive electrode and the negative electrode becomes large, and output characteristics such as discharge at a large current are obtained. There is a problem that it is easily deteriorated.

However, the gel containing the liquid-absorbent resin and the medium-polar solvent of the present invention is excellent in flexibility and can be easily attached to complicated shapes and curved surfaces. When used as a separator of a lithium ion secondary battery of the type, the generation of wrinkles is avoided by flexibility even at a large portion of the center axis side curvature of the spiral separator sandwiched between the positive electrode and the negative electrode, The distance between the positive electrode and the negative electrode can be accurately maintained, and excellent output characteristics can be maintained.

Further, the separator containing the conventional organic non-aqueous electrolyte has hygroscopicity. On the other hand, for example, in a lithium ion secondary battery, the presence of a small amount of moisture has an adverse effect on battery characteristics. from these things,
When the above-mentioned conventional separator is used, it is necessary to assemble the secondary battery in a dry environment, and there is a problem that it takes time to assemble the secondary battery.

However, the gel containing the liquid-absorbent resin and the medium-polar solvent according to the present invention does not absorb water when a medium-polar solvent is used, for example, when used as a base material of a separator for holding an electrolyte of a lithium ion secondary battery. That is, since the hygroscopicity is suppressed, it is possible to prevent the lithium ion secondary battery from deteriorating with time due to moisture absorption, and it is necessary to perform the assembly in a dry environment as in the related art in the manufacturing process of the secondary battery. Can be omitted, and the manufacturing process can be simplified.

[0066]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to each embodiment, but the present invention is not limited to the following embodiments. In the following description, “parts” and “%” indicate parts by weight and% by weight, respectively.

Example 1 Glass casting polymerization mold (size 10 × 10 × 1 cm) equipped with a thermometer and a gas inlet tube
Then, a mixed solution consisting of 99.827 parts of methoxyethyl acrylate, 0.173 parts of 1,6-hexanediol diacrylate as a crosslinkable monomer, and 0.1 parts of 2,2-azobisdimethylvaleronitrile as a polymerization initiator was injected, and a nitrogen gas flow was applied. Lower 50
The polymerization reaction was carried out by heating at 4 ° C. for 4 hours. Thereafter, the temperature was raised to 80 ° C. and maintained for 2 hours to complete the polymerization reaction. After cooling, the gel was peeled from the mold to obtain a liquid-absorbent resin (1).

When the absorption characteristics of each of the medium polar solvents were examined for the obtained liquid absorbing resin (1), the liquid absorbing resin (1) was analyzed.
Is 10 g per phenyl cellosolve (SP value: 11.5)
/ g, 17 g against γ-butyrolactone (SP value: 12.6)
/ g against propylene carbonate (SP value: 13.3)
12 g / g, and ethylene carbonate (SP value: 13.3)
And showed an absorption capacity of 13 g / g, confirming excellent liquid absorption performance with respect to a medium polar solvent. Further, the absorbency against water was 0.1 g / g or less.

Example 2 In a 1000 ml flask equipped with a thermometer, stirrer, gas inlet tube and reflux condenser, partially saponified polyvinyl alcohol (degree of saponification: 87%, degree of polymerization:
2000) 1.4 parts were dissolved in 700 parts of water and charged, and the flask was replaced with nitrogen under stirring and heated to 40 ° C. under a nitrogen stream.

Thereafter, butoxyethyl acrylate 99.9
A mixed solution consisting of 34 parts, 0.066 part of 1,6-hexanediol diacrylate as a crosslinkable monomer, and 0.5 part of 2,2-azobisdimethylvaleronitrile as a polymerization initiator was added all at once to the flask, and the mixture was added to the flask. Was stirred vigorously at 400 rpm.

Next, the temperature in the flask was raised to 70 ° C. and maintained at the same temperature for 2 hours to carry out a polymerization reaction.
The temperature was further raised to 80 ° C., and then the temperature was maintained for 2 hours to complete the polymerization reaction. After the completion of the polymerization, the particulate crosslinked polymer was separated by filtration, washed with water, and dried at 60 ° C. to obtain a liquid-absorbent resin (2) having a particle size of 100 to 1000 μm.

The absorption characteristics of each of the medium-polar solvents were examined for the obtained liquid-absorbent resin (2).
Is 11 g for phenyl cellosolve (SP value: 11.5)
/ g, a polyoxyethylene alkyl ether (manufactured by Nippon Shokubai, trade name: sophthanol 30), showing an absorption capacity of 5 g / g, confirming excellent liquid absorption performance with respect to a medium polar solvent. Further, the absorbency against water was 0.1 g / g or less.

Example 3 A mixed solution comprising 95 parts of phenoxyethyl acrylate, 5 parts of ethylene glycol dimethacrylate as a crosslinkable monomer, and 5 parts of Irgacure 184 (manufactured by Ciba Geigy) as a photopolymerization initiator was placed on a Teflon flat plate. To a thickness of 100 μm using a bar coater, and then apply a mercury lamp (used lamp; Toshiba H-400)
The film was irradiated with ultraviolet light for 5 minutes using P) to obtain a film-like liquid-absorbent resin (3).

The absorption characteristics of each of the medium-polar solvents in the obtained liquid-absorbent resin (3) were examined.
Is 8 g per phenyl cellosolve (SP value: 11.5)
/ g, 9 g against γ-butyrolactone (SP value: 12.6)
/ g, 5 g / g for propylene carbonate (SP value: 13.3), and 6 g for polyoxyethylene nonyl phenyl ether (manufactured by Kao, trade name: Emulgen 906)
/ g, indicating an excellent liquid absorption performance with respect to a medium polar solvent. The absorption capacity for water is 0.1 g / g
It was below.

Comparative Example 1 Instead of the methoxyethyl acrylate described in Example 1, 59.889 parts of methoxyethyl acrylate and 39.926 parts of N-vinylpyrrolidone were used, and the amount of 1,6-hexanediol diacrylate was 0.185.
Comparative Liquid Absorbent Resin (1) was obtained in the same manner as in Example 1 except that the composition was changed to parts.

With respect to the obtained comparative liquid-absorbent resin (1),
When the absorption characteristics of each medium polar solvent were examined, the comparative liquid-absorbent resin (1) was 2 g / g for phenylcellosolve (SP value: 11.5) and 2 g / g for γ-butyrolactone (SP value: 12.6). 1 g / g, propylene carbonate (SP value: 13.3)
It only showed an absorption capacity of 1 g / g with respect to, and it was confirmed that almost no medium-polar solvent was absorbed. In addition, the absorption capacity against water was 4 g / g, and it was confirmed that the composition exhibited large water absorption.

Next, an example of producing a gel containing a medium polar solvent useful for a battery separator of a lithium ion secondary battery or the like using an organic non-aqueous electrolyte will be described. Example 4 75 parts of propylene carbonate and 24 parts of methoxyethyl acrylate were added to a glass casting polymerization mold (size 10 × 10 × 1 cm) equipped with a thermometer and a gas inlet tube.
Parts, 1,6-hexanediol diacrylate 1 part and 2,
A mixed solution comprising 0.05 parts of 2-azobisdimethylvaleronitrile was injected, and heated at 50 ° C. for 4 hours in a nitrogen stream to carry out a polymerization reaction. Thereafter, the temperature was raised to 80 ° C. and maintained for 2 hours to complete the polymerization reaction. After cooling, the gel was peeled from the mold to obtain a gel (1) containing a medium polar solvent.

With respect to the obtained gel (1) containing a medium polar solvent, since propylene carbonate did not leak from the gel (1) containing a medium polar solvent, it was confirmed that propylene carbonate as a medium polar solvent was retained. Was done.

Example 5 A 500 ml flask equipped with a thermometer, a stirrer, a gas inlet tube and a reflux condenser was charged with 10 g of propylene carbonate, and the inside of the flask was replaced with nitrogen under stirring and under a nitrogen stream. Heated to 65 ° C.

Next, a solution composed of 38 g of methoxyethyl acrylate, 2 g of hydroxyethyl acrylate and 40 g of propylene carbonate was added to one dropping funnel, and 2,2 ′ was added to another dropping funnel as a polymerization initiator.
-Azobis (4-methoxy-2,4-dimethylvaleronitrile
A solution consisting of 0.1 g and 10 g of propylene carbonate was charged, respectively.

Subsequently, the solution and the solution were simultaneously dropped into the flask over 1 hour to carry out a polymerization reaction. Thereafter, the temperature in the flask was further raised to 80 ° C. and maintained for 2 hours to complete the polymerization. I let it.

After cooling, a solution consisting of 2.3 g of toluene diisocyanate, 0.1 g of dibutyltin dilaurate and 100 g of propylene carbonate as a crosslinking agent was added to the flask and mixed. It was applied on a flat plate using a bar coater so as to have a thickness of 100 μm, and was ground to obtain a thin film-like gel containing a medium polar solvent (2).

The obtained gel (2) containing a medium polar solvent did not leak propylene carbonate from the gel (2) containing a medium polar solvent, so it was confirmed that propylene carbonate as a medium polar solvent was retained. Was done.

The above-mentioned medium polar solvents include:
There is no particular limitation as long as the solubility parameter (SP value) is in the range of 10 to 15, but other examples of each of the above-mentioned medium polar solvents are shown below. The solubility parameter (SP value) is generally used as a scale indicating the polarity of a compound, and in this specification, a value derived by substituting Hoy's cohesive energy constant into Small's formula is applied. And the unit is (cal / cm ³ ) ^1/2 .

As the medium polar solvent having an SP value of 10.0, (iso) amyl alcohol, carbon disulfide, (ortho) dichlorobenzene, diethyl phthalate, 2,2-dimethyl-1,3-
Butanediol, 1,4-dioxane, dipropylene glycol, ethylamine, ethylene glycol diacetate, ethyl lactate, methyl isobutyl carbinol, nitrobenzene, and propionic anhydride.

Examples of the medium polar solvent having an SP value of 10.1 include acetic acid, caprolactone, 1,2-dibromoethylene, and propylene glycol methyl ether.
Examples of medium polar solvents include (meth) cresol, diethylene glycol monoethyl ether, 1,3-dioxolan,
Methyl fornate and methyl iodide are mentioned.

As the medium polar solvent having an SP value of 10.3, acetaldehyde, acetic anhydride, aniline, isobutyric acid, 2,5-hexanediol, 2-methyl-1,3-pentanediol, 1-
Nitropropane, n-octyl alcohol;
As the medium polar solvent having a P value of 10.4, cyclopentanone,
1,2-dibromoethane is exemplified.

As the medium polar solvent having an SP value of 10.5, acrylonitrile, isobutyl alcohol, n-butyric acid, butyronitrile, 2-ethyl-1-butanol, ethylene glycol monoethyl ether, hexamethylphosphoramide,
Methyl benzoate is mentioned, and as the medium polar solvent having an SP value of 10.6, bromonaphthalene, t-butanol, N, N-diethylformamide, n-heptanol and methyl salicylate are mentioned.

Examples of the medium-polar solvents having an SP value of 10.7 include dimethyl phthalate, n-hexynol, pyridine and triethylene glycol. Examples of the medium-polar solvents having an SP value of 10.8 are isobutanol and N, N-dimethylacetamide. , 2,4-pentanediol, propionitrile, quinoline and the like.
Amyl alcohol is exemplified.

Examples of the apolar solvent having an SP value of 11.0 include cyclobutanedione, dichloroacetic acid, dimethyl malonate, dimethyl oxalate, ethyl cyanoacetate, and neopentyl glycol. 2,3-butanediol, ethylene oxide, nitroethane, and the like.
Examples include N-acetylpiperidine, 2,2-dimethyl-1,2-butanediol, furfural, methacrylic acid, and methylamine.

Examples of the medium polar solvent having an SP value of 11.3 include dipropyl sulfone and N-methyl-2-pyrrolidone.
Examples of the medium-polar solvent having an SP value of 11.4 include N-acetylpyrrolidone, n-butanol, cyclohexanol, ethylene glycol monomethyl ether, and tetramethyl oxamide.
Formyl piperidine, 1,5-pentanediol, and isopropyl alcohol.

Examples of the medium-polar solvent having an SP value of 11.6 include N-acetylmorpholine and 1,3-butanediol.
Examples of the medium-polar solvent having an SP value of 11.8 include aryl alcohol and methylene iodide, and examples of the medium-polar solvent having an SP value of 11.9 include acetonitrile, n-propyl alcohol, and Sanelcizer 8;
Apolar solvents having a value of 12.0 include acrylic acid and dimethyl sulfoxide.

Examples of the medium polar solvent having an SP value of 12.1 include benzyl alcohol, 1,4-butanediol, 2,3-butylene carbonate, diethylene glycol, N, N-dimethylformamide, dimethyltetramethylene sulfone, formic acid, and hydrogen cyanide. The medium-polar solvent having an SP value of 12.2 includes ethylene chlorohydrin, and has an SP value of 1
2.3 As a medium polar solvent, N-ethylacetamide may be mentioned.

Examples of the medium-polar solvent having an SP value of 12.4 include diethyl sulfone and methylene glycolate.
Examples of the medium-polar solvent having a value of 12.5 include dimethyl phosphite, furfuryl alcohol, and methyl propyl sulfone.Examples of the medium-polar solvent having an SP value of 12.6 include butyrolactone, chloroacetonitrile, and propylene glycol. As a medium polar solvent of 12.7,
ε-caprolactam, ethyl alcohol, nitromethane.

The medium-polar solvent having an SP value of 12.9 is methyltetramethylene sulfone, the medium-polar solvent having an SP value of 13.0 is N-formylmorpholine, and the medium-polar solvent having an SP value of 13.1 is N, N -Dimethylnitroamine, a medium polar solvent having an SP value of 13.3, includes propiolactone, 1,2-
Examples of propylene carbonate and a medium polar solvent having an SP value of 13.4 include methyl ethyl sulfone, γ-pyrone, and tetramethylene sulfone.

As a polar solvent having an SP value of 13.6, maleic anhydride and piperidone, a polar solvent having an SP value of 13.7, N, N-diacetylpiperazine, and a polar solvent having an SP value of 13.9, N -Atylformamide, SP value 1
4.5 As a polar solvent, methanol, dimethyl sulfone, SP value of 14.6 As a polar solvent, ethylene glycol, N-methylacetamide, SP value of 14.7 As a polar solvent, ethylene carbonate, α-pyrrolidone No.

[0097]

As described above, the liquid-absorbent resin of the present invention comprises:
The composition is obtained by polymerizing a monomer component containing at least 85% by weight of at least one monomer (A) selected from the group consisting of alkoxyalkyl (meth) acrylate and phenoxyalkyl (meth) acrylate.

Therefore, the above-mentioned constitution is obtained by polymerizing the above-mentioned monomer components, so that the solubility parameter is 10-1.
5 can be widely absorbed, and has hydrophobicity which does not absorb water.

Thus, in the above structure, the medium-polar solvent can be easily recovered by absorption, and by not absorbing water, the absorption of moisture during storage can be suppressed. Can be prevented from decreasing. Therefore, the configuration described above has an effect that the conventional trouble of storing in a dry environment can be avoided.

As described above, the gel containing a medium polar solvent according to the present invention has a solubility parameter (SP)
This is a configuration in which a medium polar solvent having a value of 10 to 15 is retained by swelling of the liquid absorbing resin.

Therefore, in the above-described structure, since the liquid-absorbent resin holds the medium-polarity solvent by swelling, the liquid-absorbent resin 1
The solubility parameter (SP value) is 10 to 15 parts by weight.
Can be held in a large amount, for example, 3 to 20 parts by weight, and the liquid absorbing performance of the medium polar solvent can be improved.

As a result, the above structure can absorb a large amount of medium-polarity solvent, and has a reduced hygroscopic property of the liquid absorbing resin to absorb moisture. As compared with the case of using, the hygroscopicity to the liquid-absorbent resin containing a medium-polarity solvent is also suppressed, and by avoiding the need to handle the above configuration under dry conditions, the handling of the above configuration can be simplified. This has the effect.

Claims (6)

[Claims] 1. A monomer component containing at least 85% by weight of at least one monomer (A) selected from the group consisting of alkoxyalkyl (meth) acrylate and phenoxyalkyl (meth) acrylate. A liquid-absorbent resin characterized in that: 2. A compound of the general formula (1) (In the above formula, R ₁ represents hydrogen or a methyl group, and R ₂ represents a methyl group, an ethyl group, a butyl group, a propyl group, or a phenyl group.)
A liquid-absorbent resin obtained by polymerizing a monomer component containing at least 85% by weight of a seed monomer (A). 3. The method according to claim 1, wherein the monomer component has a crosslinkable monomer for forming a three-dimensional crosslinked structure.
Or the liquid-absorbent resin according to 2. 4. The crosslinkable monomer is such that the crosslinkable unit in the crosslinkable monomer is based on the total amount of the monomer units of the monomer component.
The liquid-absorbent resin according to claim 3, which is contained in an amount of 0.001 to 5 mol%. 5. The liquid absorbing resin according to claim 3, wherein a medium polar solvent having a solubility parameter (SP value) of 10 to 15 is retained by swelling of the liquid absorbing resin. Gel containing medium polar solvent. 6. A liquid absorbing resin which is obtained by polymerizing the monomer component according to claim 3 or 4 in the presence of a medium polar solvent, and retains the medium polarity solvent by swelling. Gel containing medium polar solvent.