JP2021066758A - Copolymer - Google Patents

Abstract

To provide a copolymer suitable for a hydrogel, which has good strength and is excellent in water holding property and lubricity.SOLUTION: Provided is a copolymer comprising a structural unit (a) derived from a hydrophilic vinyl monomer and a structural unit (b) derived from a hydrophobic vinyl monomer. Q values of the hydrophilic vinyl monomer and the hydrophobic vinyl monomer are 0.5 or less respectively and e values thereof are -2.2 or more respectively. Copolymerizability ratios of the hydrophilic vinyl monomer and the hydrophobic vinyl monomer, r1 and r2, satisfy the following conditions (1) and condition (2): condition (1), 0.01≤r1≤1 and 0.1≤r2≤20; and condition (2), r1×r2≤1.SELECTED DRAWING: None

Description

The present invention relates to copolymers suitable for forming hydrogels.

Since hydrogel has excellent properties such as water absorption, water retention, and lubricity, various technologies such as medical, food, industrial use, construction, and civil engineering can be used as water absorption materials, water retention materials, industrial materials, and biological substitute materials. It is expected to be applied to the field.
For example, Patent Document 1 describes a composition containing a water-absorbent resin (A) and a monomer component (B) containing a water-soluble monofunctional vinyl monomer (b1) and a bifunctional (meth) acrylate (b2). A cured hydrogel is disclosed. Patent Document 2 discloses a soft contact lens using a silicone hydrogel, and describes that it has excellent wettability. Patent Document 3 discloses an adhesive hydrogel that can be suitably used as a raw material for biological electrodes, medical adhesives, cosmetics, quasi-drugs, electrodes for industrial measurement, and the like. Patent Document 4 discloses a gel having high mechanical strength and capable of maintaining the wettability of the surface for a long time.

Japanese Unexamined Patent Publication No. 2019-11971 Japanese Unexamined Patent Publication No. 2016-153894 Japanese Unexamined Patent Publication No. 2012-144581 Japanese Unexamined Patent Publication No. 2016-124955

Hydrogel can be applied to a wider range of fields by using a material in which desired properties such as mechanical strength, water retention and lubricity are precisely controlled according to various uses.
An object of the present invention is to provide a resin which has good strength and can obtain a hydrogel having excellent water retention and lubricity.

The present invention includes the following aspects.
[1] A copolymer containing a structural unit (a) derived from a hydrophilic vinyl monomer and a structural unit (b) derived from a hydrophobic vinyl monomer.
The Q value of each of the hydrophilic vinyl monomer and the hydrophobic vinyl monomer is 0.5 or less, and the e value is -2.2 or more.
A copolymer characterized in that the copolymerizability ratios r1 and r2 of the hydrophilic vinyl monomer and the hydrophobic vinyl monomer satisfy the following conditions (1) and (2).
Condition (1): 0.01 ≦ r1 ≦ 1 and 0.1 ≦ r2 ≦ 20
Condition (2): r1 × r2 ≦ 1
[2] The copolymer according to [1], wherein the Q value is 0.02 to 0.5 and the e value is -2.2 to 0.
[3] The hydrophobic vinyl monomer is an alicyclic vinyl, an aromatic vinyl, an aliphatic acid vinyl ester, an aromatic acid vinyl ester, an alicyclic acid vinyl ester, an aliphatic vinyl ether, an aromatic vinyl ether, or an alicyclic vinyl ether. , And the copolymer according to [1] or [2], which is one or more selected from fluorine group-containing vinyl.
[4] The hydrophilic vinyl monomer is any one or more selected from N-vinyllactams, N-vinylamides, vinylsulfonic acids, and hydroxyl group-containing vinyls [1] to [3]. The copolymer described.
[5] The hydrophobic vinyl monomer is one or more selected from vinyl acetate, vinyl hexanoate, vinyl pivalate, vinyl benzoate, n-butyl vinyl ether, and phenyl vinyl ether [1] to [4]. The copolymer according to any one.
[6] Any one of [1] to [5], wherein the hydrophilic vinyl monomer is at least one selected from N-vinyl-ε-caprolactam, N-vinyl-2-pyrrolidone, and N-vinylacetamide. The copolymer according to.
[7] The copolymer according to any one of [1] to [6], wherein the glass transition temperature (Tg) is 0 ° C. or higher.
[8] The molar ratio of the structural unit (a) derived from the hydrophilic vinyl monomer and the structural unit (b) derived from the hydrophobic vinyl monomer (constituent unit (a): structural unit (b)) is 20:80 to 80. : 20. The copolymer according to any one of [1] to [7].
[9] A hydrogel containing the copolymer and water according to any one of [1] to [8].

According to the present invention, it is possible to provide a resin which has good strength and can obtain a hydrogel having excellent water retention and lubricity.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the embodiments shown below.

[Copolymer]
The copolymer of the present embodiment contains a structural unit (a) derived from a hydrophilic vinyl monomer and a structural unit (b) derived from a hydrophobic vinyl monomer. The hydrophilic vinyl monomer and the hydrophobic vinyl monomer each have a Q value of 0.5 or less and an e value of -2.2 or more. The copolymerization ratios r1 and r2 of the hydrophilic vinyl monomer and the hydrophobic vinyl monomer satisfy the following conditions (1) and (2).
Condition (1): 0.01 ≦ r1 ≦ 1 and 0.1 ≦ r2 ≦ 20
Condition (2): r1 × r2 ≦ 1

<Q value, e value>
The Q value and e value in the present specification are empirical parameters in the Q and e theory of Alfrey-Price, and are based on styrene (Q value: 1.0, e value: -0.8). And. Regarding Q and e theory, general textbooks on polymer chemistry, such as Takayuki Otsu, "Chemistry of Polymer Synthesis" (Chemistry, 1979), pp. 116-120, Shohei Inoue, "Synthetic Polymer Chemistry" (裳) Hanafusa, 2011) 89-91, Takeshi Endo, "Synthesis of Polymers (1)" (Kodansha, 2010) 69-71, Tadaomi Nishikubo, "Basic Master Polymer Chemistry" (Ohm, 2011) 182 , J. Brandrup, E.I. H. Immunogut, E.I. A. There is a description in Grulke's editorial Polymer Handbook 4th Edition, "Free Radical Copolymation Reactivity Ratios", etc., and Q values and e values of various monomers are obtained based on styrene.
The Q value is an index of how much the radical can be stabilized when it is added to the monomer, and the higher the value, the greater the resonance stabilizing effect. The e value indicating the polar effect is used as a measure of the electron density of the polymerizable double bond. If the substituent is electron-withdrawing, it shows a negative value, and the larger the absolute value of the negative value, the more the polymerizable double bond. The electron density is low.

Each of the vinyl monomers constituting the copolymer in the present invention has a Q value of 0.5 or less. The value of the Q value is preferably 0.02 to 0.5, and more preferably 0.02 to 0.2. Further, the hydrophilic vinyl monomer preferably has a Q value of 0.08 to 0.18, and the hydrophobic vinyl monomer further preferably has a Q value of 0.025 to 0.05. If the Q value is larger than 0.5, problems such as gelation and poor control of the monomer arrangement occur when the vinyl monomer is polymerized. If the monomer arrangement cannot be controlled well, the arrangement of the structural unit (a) derived from the hydrophilic vinyl monomer and the structural unit (b) derived from the hydrophobic vinyl monomer will vary, and when the copolymer is used as a material for hydrogel. In addition, it is not preferable because it leads to variations in water retention and lubricity. All of the vinyl monomers constituting the copolymer in the present invention have an e value of -2.2 or more. The value of the e value is preferably 2.2 to 0, and more preferably -1.7 to -0.3. Further, the hydrophilic vinyl monomer preferably has an e value of −1.65 to -1.10, and the hydrophobic vinyl monomer further preferably has an e value of -2.2 to −0.40. If the value of the e value is less than -2.2, the reactivity at the time of synthesizing the copolymer is adversely affected, and problems such as poor control of the monomer sequence occur.

<Copolymerization ratio>
The copolymerizability ratios r1 and r2 in the present specification represent the ratio of the rate constants when one of the hydrophilic vinyl monomers described later and one of the hydrophobic vinyl monomers described below are copolymerized. That is, the copolymerizability ratios r1 and r2 are obtained when one selected from the hydrophobic vinyl monomers is a vinyl monomer (M ₁ ) and one selected from the hydrophilic vinyl monomers is a vinyl monomer (M ₂ ). It can be calculated by the following equations (1) and (2) using the Q value and e value of the monomer.

r1 = k ₁₁ / k ₁₂ = Q ₁ / Q ₂ · exp {-e ₁ (e _1- e ₂ )} (1)
r2 = k ₂₂ / k ₂₁ = Q ₂ / Q ₁ · exp {-e ₂ (e _2- e ₁ )} (2)
In the formula (1) and (2), _{Q 1} is Q value of the vinyl monomer _{(M 1), e 1} is the e value of the vinyl monomer _{(M 1), Q 2} is vinyl monomers _(M 2) Is the Q value of, and e ₂ is the e value of the vinyl monomer (M _2).

The copolymerizability ratios r1 and r2 of the hydrophilic vinyl monomer and the hydrophobic vinyl monomer satisfy the following conditions (1) and (2).
Condition (1): 0.01 ≦ r1 ≦ 1 and 0.1 ≦ r2 ≦ 20
Condition (2): r1 × r2 ≦ 1
When the values of the copolymerization ratios r1 and r2 satisfy the condition (1), the arrangement of the monomers constituting the copolymer is controlled, and when used as a material for a hydrogel, water retention, swelling property, lubricity, etc. Performance can be improved without variation. Further, when the values of the copolymerizability ratios r1 and r2 satisfy the condition (2), the copolymer improves the randomness of the arrangement of the _{vinyl monomer (M 1} ) and the vinyl monomer (M _2). That is, by controlling the arrangement (randomness) of the structural unit (a) derived from the hydrophilic vinyl monomer and the structural unit (b) derived from the hydrophobic vinyl monomer in the copolymer, water retention when used as a hydrogel. , Desired performance such as swelling property and lubricity can be uniformly controlled without variation. The copolymerization ratios r1 and r2 of the hydrophilic vinyl monomer and the hydrophobic vinyl monomer more preferably satisfy the following conditions (1) and (2).
Condition (1): 0.1 ≤ r1 ≤ 0.6 and 0.5 ≤ r2 ≤ 10
Condition (2): 0.2 ≦ r1 × r2 ≦ 1

When the copolymer has a structural unit derived from two or more kinds of hydrophilic vinyl monomers, or when it has a structural unit derived from two or more kinds of hydrophobic vinyl monomers, the hydrophilic vinyl monomer and the hydrophobic vinyl It is preferable to calculate the copolymerizability ratios r1 and r2 for all possible combinations of monomers and satisfy the conditions (1) and (2).

For example, when the vinyl monomer constituting the copolymer consists of four types, a hydrophilic vinyl monomer (a1), a hydrophilic vinyl monomer (a2), a hydrophobic vinyl monomer (b1), and a hydrophobic vinyl monomer (b2), it is hydrophilic. A combination of a sex vinyl monomer (a1) and a hydrophobic vinyl monomer (b1), a combination of a hydrophilic vinyl monomer (a1) and a hydrophobic vinyl monomer (b2), a hydrophilic vinyl monomer (a2) and a hydrophobic vinyl monomer (b1). The copolymerizability ratios r1 and r2 were calculated for each of the combination of the hydrophilic vinyl monomer (a2) and the hydrophobic vinyl monomer (b2), and the values of these copolymerizability ratios were the conditions (1) and the conditions. It is preferable to satisfy (2).

<Hydrophilic vinyl monomer>
In the present specification, the "hydrophilic vinyl monomer" is water-soluble when one kind is polymerized alone to form a homopolymer, or at least 10% by mass of water in the method for measuring the water absorption rate described later. It refers to a vinyl monomer from which a homopolymer capable of absorbing water can be obtained. The hydrophilic vinyl monomer is not particularly limited as long as it is a vinyl compound having the hydrophilicity defined above, and examples thereof include N-vinyllactams, N-vinylamides, vinylsulfonic acids, and hydroxyl group-containing vinyls. Can be mentioned. Specifically, N-vinyl-ε-caprolactam (Q value 0.14, e value -1.14), N-vinyl-2-pyrrolidone (Q value 0.088, e value -1.62), N. -Vinylformamide, N-vinylacetamide (Q value 0.16, e value-1.57), N-vinylisopropylamide, N-vinyl-N-methylacetamide, 2-hydroxyethylvinyl ether, vinyl alcohol (in the copolymer) Hydrolyzed type of vinyl acetate) and the like. Among these, N-vinyl-ε-caprolactam, N-vinyl-2-pyrrolidone, and N-vinylacetamide are preferable from the viewpoint of water retention, swelling property, lubricity, etc. when used as a material for hydrogel.

<Hydrophobic vinyl monomer>
In the present specification, the "hydrophobic vinyl monomer" refers to only water that is water-insoluble and less than 10% by mass in the method for measuring the water absorption rate described later when one kind is polymerized alone to form a homopolymer. A vinyl monomer from which a non-absorbable homopolymer can be obtained. The hydrophobic vinyl monomer is not particularly limited as long as it is a vinyl compound having the hydrophobicity defined above, and for example, alicyclic vinyl, aromatic vinyl, aliphatic acid vinyl ester, aromatic acid vinyl ester, and the like. Examples thereof include alicyclic acid vinyl esters, aliphatic vinyl ethers, aromatic vinyl ethers, alicyclic vinyl ethers, and fluorine group-containing vinyls. Specifically, vinylcyclohexane, vinyltoluene, vinyl acetate (Q value 0.026, e value -0.88), vinyl propionate, vinyl butyrate, vinyl valerate, vinyl hexanoate (Q value 0.025, e) Value -0.47), vinyl pivalate (Q value 0.05, e value -1.3), vinyl benzoate (Q value 0.03, e value -0.89), vinyl cyclohexanecarboxylic acid, vinyl ethyl Examples thereof include ether, n-butyl vinyl ether (Q value 0.038, e value -1.5), phenyl vinyl ether (Q value 0.046, e value -2.16), cyclohexyl vinyl ether and the like. Among these, vinyl acetate, vinyl hexanoate, vinyl pivalate, vinyl benzoate, n-butyl vinyl ether, and phenyl vinyl ether are preferable from the viewpoint of water retention, swelling property, lubricity, etc. when used as a material for hydrogel. ..

The molar ratio of the structural unit (a) derived from the hydrophilic vinyl monomer and the structural unit (b) derived from the hydrophobic vinyl monomer (constituent unit (a): structural unit (b)) is preferably 20:80 to 80:20. , 30:70 to 70:30, more preferably 40:60 to 60:40. When the molar ratio is in the above range, when the copolymer is used as a material for the hydrogel, desired performances such as water retention, swelling property, and lubricity are satisfactorily exhibited without variation.

Since the molar ratio of each constituent unit can be adjusted according to the blending ratio of the hydrophilic vinyl monomer and the hydrophobic vinyl monomer when synthesizing the copolymer, the hydrophilic vinyl monomer and the hydrophilic vinyl monomer at the time of synthesizing the copolymer The compounding ratio (molar ratio) of the hydrophobic vinyl monomer is preferably adjusted to be 20:80 to 80:20, more preferably 30:70 to 70:30, and further preferably 40:60 to 60:40. Good. In this embodiment, the compounding ratio of each monomer is regarded as the molar ratio of the copolymer.

The weight average molecular weight of the copolymer is preferably 4000 to 30000, more preferably 5000 to 20000, and even more preferably 5500 to 10000. When the weight average molecular weight is 4000 or more, the performance such as water retention, swelling property, and lubricity when the copolymer is used as a hydrogel is good. When the weight average molecular weight is 30,000 or less, the viscosity of the copolymer is not too high, the workability when the composition is added with a solvent or the like is excellent, and the copolymer is processed into a desired shape such as a film or pellet. It's easy to do.

The molecular weight distribution (Mw / Mn) of the copolymer is preferably 1.5 to 4.0, more preferably 1.5 to 3.5, and 1.5 to 3.0. Is even more preferable. When the molecular weight distribution (Mw / Mn) of the copolymer is 1.5 or more, the reaction conditions for producing the copolymer can be set with a relatively wide range, so that resin design is easy. Further, when the molecular weight distribution (Mw / Mn) is 4.0 or less, the copolymer can be used without variation in performance when it is used as a material for hydrogel.

In the present invention, the weight average molecular weight and the molecular weight distribution (Mw / Mn) are values measured by gel permission chromatography (GPC) under the following conditions and calculated in terms of polystyrene.
Column: 3 TSK gel Super HM-N manufactured by Tosoh Corporation Column temperature: 40 ° C
Sample: 0.2% tetrahydrofuran solution of copolymer Developing solvent: Tetrahydrofuran Detector: RI detector (RI-71S manufactured by Showa Denko)
Flow velocity: 0.6 mL / min

The glass transition temperature (Tg) of the copolymer is preferably 0 ° C. or higher, and more preferably 10 ° C. or higher. When the glass transition temperature is 0 ° C. or higher, the flow of the hydrogel can be suppressed and the desired shape can be maintained under the usage environment when the hydrogel is used as a material, which is preferable.

The glass transition temperature is determined by applying a copolymer solution to a glass substrate, drying it at 50 ° C. under reduced pressure for 24 hours, redissolving it in acetone, and drying it again at 50 ° C. under reduced pressure for 24 hours. The solid content obtained by removing the volatile components is measured using DSC (differential scanning calorimetry, measuring device: Seiko DSC6200) under a nitrogen gas stream at a temperature rise rate of 10 ° C./min in accordance with JIS-K7121. It is the intermediate point glass transition temperature.

<Method for producing copolymer>
The method for producing the copolymer is not particularly limited, and for example, a hydrophilic vinyl monomer and a hydrophobic vinyl monomer are polymerized by using a polymerization method such as radical polymerization, cationic polymerization, anionic polymerization, or coordination anionic polymerization. The method can be mentioned. Specifically, a polymerization initiator is added to a solution obtained by mixing a hydrophilic vinyl monomer and a hydrophobic vinyl monomer at a concentration of 10 to 50% by mass with a solvent inert to the polymerization reaction, and the temperature is 70 to 120 ° C. It is preferable to use a method of radical polymerization by reacting for 5 to 10 hours.

The content (molar ratio) of the constituent units derived from each vinyl monomer of the copolymer corresponds to the molar ratio of the vinyl monomer as a raw material of the copolymer. Therefore, by adjusting the type and molar ratio of the vinyl monomer that is the raw material of the copolymer, a copolymer containing a predetermined constituent unit in a predetermined content (molar ratio) can be obtained.

Examples of the radical polymerization initiator used in producing the copolymer include 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-butyronitrile), and 2,2'. -Azobisisobutyronitrile, dimethyl-2,2'-azobisisobutyrate, dimethyl-2,2-azobis (2-methylpropionate) and 1,1'-azobis (cyclohexane-1-carbonitrile) ) Etc.; benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, t-butylperoxy Examples include acetate and organic peroxides such as t-butylperoxybenzoate.

The amount of the polymerization initiator used in producing the copolymer is preferably 1 to 15 parts by mass, more preferably 2 to 10 parts by mass, based on 100 parts by mass of the total vinyl monomer as a raw material of the copolymer. ..

Solvents used in the production of copolymers include methanol, ethanol, 1-propanol, isopropyl alcohol, butanol, ethylene glycol, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, dioxane, toluene, xylene, ethyl acetate and isopropyl acetate. , Normal propyl acetate, butyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, ethylene glycol monoethyl ether acetate, 3-methoxybutyl acetate, methyl-3-methoxypropionate, ethylene glycol mono Butyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, 3-methoxybutanol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, ethyl lactate. And so on.

When polymerizing the copolymer, a chain transfer agent may be used for the purpose of adjusting the molecular weight. Specific examples of the chain transfer agent include alkyl mercaptans such as octyl mercaptan, nonyl mercaptan, decyl mercaptan, and dodecyl mercaptan.

<Hydrogel>
The hydrogel of the present invention contains the above-mentioned copolymer and water. By using the above-mentioned copolymer as the material of the hydrogel, the water retention, swelling property, lubricity, etc. can be adjusted within a desired range without variation, so that it can be applied to various applications in which the hydrogel is used. Can be done. The hydrogel can be produced by processing the above-mentioned copolymer into a desired shape such as a film or pellet, and then contacting or immersing the copolymer in a predetermined amount of water for, for example, about 1 minute to 1 hour. The amount of water to be absorbed, the immersion time, and the like may be appropriately adjusted according to the performance of the hydrogel in the intended application.

The hydrogel of the present invention may further contain glycols and / or polyhydric alcohols. Examples of glycols include those having a polyether structure such as polyethylene glycol and polypropylene glycol. Examples of polyhydric alcohols include propylene glycol, 1,3-butylene glycol, glycerin and the like. These may be used individually by 1 type, and may be used in combination of 2 or more type.

Specific applications using hydrogel include, for example, a hydrogel model (Japanese Patent Laid-Open No. 2019-163473) suitable for an organ model for practicing procedures such as surgery, and an electrode material used for diagnosis / treatment in medical treatment is fixed to a living body. Materials (Japanese Patent Laid-Open No. 2019-92530), drug carriers used in drug delivery systems (Japanese Patent Laid-Open No. 2018-168293), hydrogels used as battery separators and electrolytes (Japanese Patent Laid-Open No. 2019-38923), soft contact lenses and catheters. Materials used for improving lubricity in an aquatic environment (Japanese Patent Laid-Open No. 2016-153894, JP-A-2015-57081), skin adhesive materials for collecting skin secretions (Japanese Patent Laid-Open No. 2019-124667), at the time of peeling. Sheet-shaped packs with reduced pain (Japanese Patent Laid-Open No. 2018-39802), hydrogel materials for adsorbing and removing impurities, etc. 2019-86505, JP-A-2016-34006), a process material in the industrial field that is suitably used for applications such as preparing a coating film in a predetermined step and removing the coating film when it is no longer necessary (Japanese Patent Laid-Open No. 9-139343, special feature). Kaihei 7-185876, JP-A-2016-34006) and the like can be mentioned.

When the hydrogel of the present embodiment is used as a process material, for example,
A step of preparing a solution by mixing the copolymer and an organic solvent,
A step of coating a base material with the solution by a method such as coating, spraying, or dipping, and volatilizing an organic solvent to prepare a coating film.
A step of removing the hydrogel by contacting the coating film with water to form a hydrogel and lowering the adhesive strength after the completion of a predetermined step such as processing.
Examples of the usage method include a process such as.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Synthesis Example 1]
122.9 g of propylene glycol monomethyl ether (PGME) was added to a flask equipped with a stirrer, a dropping funnel, a condenser, a thermometer and a gas introduction tube, and the mixture was stirred while replacing nitrogen, and the temperature was raised to 90 ° C. Then, 14.1 g of dimethyl 2,2-azobis (2-methylpropionate) was added to a vinyl monomer mixture consisting of 69.5 g (0.5 mol) of vinyl caprolactam and 71.0 g (0.5 mol) of vinyl chloride. ) (Polymer initiator, manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., V-601 (registered trademark)) was added dropwise to the flask over 2 hours from the dropping funnel. After completion of the dropping, the mixture was further stirred at 90 ° C. for 2 hours to carry out a copolymerization reaction to obtain a copolymer solution. Further, PGME was added to obtain a copolymer (A-1) solution (weight average molecular weight 7500) having a solid content concentration of 30% by mass. Table 1 shows the value of the product of the copolymerizability ratios r1 and r2 and the copolymerizability ratios r1 × r2 calculated from the Q value and e value of the hydrophilic vinyl monomer and the hydrophobic vinyl monomer.

The solid content is the residue obtained by removing the residual monomer and the solvent component from the copolymer solution, and the solid content concentration is a value calculated by the following method.

<Calculation of solid content concentration>
Weigh 0.5 g of the copolymer (A-1) solution in a mass-measured aluminum cup and spread it thinly. This was left in an oven at 140 ° C. for 1 hour, the mass of the residue of the copolymer (A-1) solution was measured again, and the solid content concentration was calculated.

[Synthesis Examples 2 to 19]
Solutions of copolymers (A-2) to (A-19) were obtained in the same manner as in Synthesis Example 1 except that the compounding ratios shown in Tables 1 to 3 were used. The values of the products of the weight average molecular weight, the copolymerization ratio, and the copolymerization ratio of each are shown in Tables 1 to 3.

[Comparative Synthesis Examples 1 to 6]
Solutions of copolymers (B-1) to (B-6) were obtained in the same manner as in Synthesis Example 1 except that the compounding ratios shown in Table 4 were used. The values of the products of the weight average molecular weight, the copolymerization ratio, and the copolymerization ratio of each are shown in Table 4.

<Evaluation of copolymer>
Using the copolymers (A-1) to (A-19) and the copolymers (B-1) to (B-6) obtained in Synthesis Examples 1 to 19 and Comparative Synthesis Examples 1 to 6, The amount of residual monomer, water absorption rate, swelling degree, and coefficient of dynamic friction in water were measured by the following methods. The results are shown in Tables 5-8.

<Measurement of residual monomer amount>
The copolymer solution obtained in the synthesis example was diluted 100-fold with acetone, and the amount of various residual monomers was measured using gas chromatography 2010 manufactured by SHIMADZU. The quantification of the residual monomer was performed using the calibration curve of various monomers, and the total amount (mass%) of the total residual monomer was shown in Tables 5 to 8 as the "residual monomer amount".

<Measurement of water absorption rate>
The copolymer solution obtained in the synthesis example was applied to a glass plate using a bar coater and heated at 120 ° C. for 20 minutes to volatilize the solvent to prepare a coating film having a film thickness of 5 μm. The prepared coating film was immersed in water for 10 minutes under the condition of 23 ° C. to prepare a hydrogel. After taking out the hydrogel and wiping off the moisture adhering to the surface with a cloth, the coating film was scraped off, and the water absorption rate (mass%) was measured with a moisture measuring device (701KF Titrino manufactured by Metrohm).

<Measurement of swelling degree>
A copolymer solution in which the amount of solvent was reduced to 10% by mass by an evaporator was poured onto a peeling PET film surrounded by a 6 mm thick Teflon (registered trademark) sheet, and the pressure was reduced at 100 ° C. to achieve a thickness of 0.5 mm. Film was prepared. The film was cut into a length of 20 mm and a width of 20 mm to prepare a sample. The sample was immersed in water for 1 hour under the condition of 23 ° C. to prepare a hydrogel. The length and width of this hydrogel (swelled sample) were measured, and the degree of swelling (α) was calculated by the following formula, assuming that it swelled isotropically.
α = (L1 × L2 / 400) ^3/2 (1)
L1, L2: Vertical and horizontal lengths (mm) of the swollen sample

<Measurement of underwater dynamic friction coefficient>
A coating film having a film thickness of 5 μm was prepared in the same manner as in the measurement of the water absorption rate. The coating film was immersed in water at 23 ° C., and the coefficient of dynamic friction after 10 minutes was measured. A pin / disk type surface measuring machine 14DR-ANL (manufactured by Shinto Kagaku Co., Ltd.) was used to measure the coefficient of kinetic friction. As the measurement conditions, a SUS flat indenter having a curvature of 10 mmφ was used, and the coefficient of dynamic friction in water was measured at a sliding speed of 5 mm / s and a load of 400 gf.

As shown in Examples 1 to 19, it can be seen that the copolymer of the present invention has a small amount of residual monomers and can effectively suppress contamination and bleeding on the adherend. Further, it can be seen that the hydrogel has excellent performance such as high water absorption rate and swelling degree and low underwater dynamic friction coefficient, and can be suitably used for various purposes.

On the other hand, in Comparative Examples 1 to 6 in which the values such as Q value, e value, and copolymerization ratio are different, good performance as a hydrogel is obtained, such as a large amount of residual monomer and a small water absorption rate. I couldn't.

According to the present invention, there is provided a resin which has good strength and can obtain a hydrogel having excellent water retention and lubricity. The resin can be preferably used as a water-absorbing material, a water-retaining material amount, an industrial material, a biological substitute material, and the like in various technical fields such as medical care, food, industrial use, construction, and civil engineering.

Claims (9)

A copolymer containing a structural unit (a) derived from a hydrophilic vinyl monomer and a structural unit (b) derived from a hydrophobic vinyl monomer.
The Q value of each of the hydrophilic vinyl monomer and the hydrophobic vinyl monomer is 0.5 or less, and the e value is -2.2 or more.
A copolymer characterized in that the copolymerizability ratios r1 and r2 of the hydrophilic vinyl monomer and the hydrophobic vinyl monomer satisfy the following conditions (1) and (2).
Condition (1): 0.01 ≦ r1 ≦ 1 and 0.1 ≦ r2 ≦ 20
Condition (2): r1 × r2 ≦ 1 The copolymer according to claim 1, wherein the Q value is 0.02 to 0.5 and the e value is -2.2 to 0. The hydrophobic vinyl monomer is an alicyclic vinyl, an aromatic vinyl, an aliphatic acid vinyl ester, an aromatic acid vinyl ester, an alicyclic acid vinyl ester, an aliphatic vinyl ether, an aromatic vinyl ether, an alicyclic vinyl ether, and fluorine. The copolymer according to claim 1 or 2, which is one or more selected from group-containing vinyls. The copolymer according to any one of claims 1 to 3, wherein the hydrophilic vinyl monomer is at least one selected from N-vinyllactam, N-vinylamide, vinylsulfonic acid, and hydroxyl group-containing vinyl. The present invention according to any one of claims 1 to 4, wherein the hydrophobic vinyl monomer is at least one selected from vinyl acetate, vinyl hexanoate, vinyl pivalate, vinyl benzoate, n-butyl vinyl ether, and phenyl vinyl ether. The copolymer described. The invention according to any one of claims 1 to 5, wherein the hydrophilic vinyl monomer is at least one selected from N-vinyl-ε-caprolactam, N-vinyl-2-pyrrolidone, and N-vinylacetamide. Copolymer. The copolymer according to any one of claims 1 to 6, wherein the glass transition temperature (Tg) is 0 ° C. or higher. The molar ratio of the structural unit (a) derived from the hydrophilic vinyl monomer and the structural unit (b) derived from the hydrophobic vinyl monomer (constituent unit (a): structural unit (b)) is 20:80 to 80:20. The copolymer according to any one of claims 1 to 7. A hydrogel containing the copolymer and water according to any one of claims 1 to 8.