JP4738046B2 - Vinylpyrrolidone copolymer and process for producing the same - Google Patents

Description

  The present invention relates to a vinylpyrrolidone-based copolymer containing N-vinylpyrrolidone and a hydroxyl group-containing (meth) acrylate such as 2-hydroxyethyl (meth) acrylate as essential components and a method for producing the same.

  A copolymer of N-vinyl pyrrolidone and 2-hydroxyethyl (meth) acrylate (hereinafter also referred to as “NVP / HE (M) A copolymer”) is a cross-linked hydrophilic pyrrolidone group and isocyanate. Since it has an advantage of having a hydroxyl group capable of reacting with an agent, it is known to be useful, for example, as a raw material polymer of a curable resin composition for obtaining a film having both water resistance and hydrophilicity. . For example, it is preferable in a curable resin composition (see Patent Document 1) containing, as essential components, a polymer having an N-vinylamide unit, a compound having two or more functional groups that react with active hydrogen, and a polyvalent metal compound. It is used as a polymer.

An NVP / HE (M) A copolymer is conventionally obtained by adding 2-hydroxyethyl (meth) acrylate and polymerizing it in water (solvent) containing N-vinylpyrrolidone and a polymerization initiator. Generally, this method is adopted as a method for producing the NVP / HE (M) A copolymer.
JP 2003-286281 A

However, when the NVP / HE (M) A copolymer obtained by the conventional technique is formed by crosslinking a curable resin composition using this as a raw material polymer, the surface of the formed crosslinked coating film In addition to problems such as poor smoothness and gel swelling when performing washing with water to remove unreacted raw materials after crosslinking, the uniformity of the formed crosslinked coating film is reduced. Etc. had occurred. Moreover, the conventional crosslinked coating film using a NVP / HE (M) A copolymer as a raw material polymer has a problem of low water resistance.
The above has been a problem common to vinylpyrrolidone copolymers having a hydroxyl group-containing (meth) acrylate represented by 2-hydroxyethyl (meth) acrylate as one raw material monomer.

  Thus, the problem to be solved by the present invention is that N-vinylpyrrolidone and a hydroxyl group-containing (meth) acrylate such as 2-hydroxyethyl (meth) acrylate, which can obtain a good crosslinked coating film that does not cause the above problems, and It is an object to provide a vinylpyrrolidone copolymer having an essential component as a component and a production method capable of easily obtaining this.

  The present inventor has intensively studied to solve the above problems. As a result, when the conventional NVP / HE (M) A copolymer is used as a raw material polymer, the above-mentioned problem occurs because 2-hydroxyethyl (meth) acrylate is susceptible to a crosslinking reaction during polymerization. The present inventors have found that the water-insoluble content (that is, the gel content) is increased and the molecular weight distribution is widened. That is, when a curable resin composition using the NVP / HE (M) A copolymer obtained by the conventional technique as a raw material polymer is formed into a film and cross-linked, the water-insoluble content is high, so that a cross-linked coating film is formed. In addition to problems such as poor surface smoothness of the gel and swelling of the gel during washing after crosslinking, problems such as low uniformity of the crosslinked coating due to wide molecular weight distribution Had occurred. The present inventor further found that the water resistance of the crosslinked coating film is influenced by the K value of the NVP / HE (M) A copolymer.

  Therefore, the present inventor has a vinylpyrrolidone-based copolymer that can achieve a low water-insoluble content and / or a low dispersity while N-vinylpyrrolidone and a hydroxyl group-containing (meth) acrylate are essential components. As a result of various investigations and repeated experiments with respect to a production method capable of easily obtaining this, the following knowledge was reached and the present invention was completed. That is, whether the copolymerization ratio of N-vinylpyrrolidone and hydroxyl group-containing (meth) acrylate is set to a specific range, and i) is polymerized in the presence of a specific amount of chain transfer agent. Or a copolymer having a very low water-insoluble content can be obtained by polymerizing in a solvent containing a specific alcohol above a certain level, ii) using a mercapto compound as a chain transfer agent, A copolymer having a very low degree of dispersion can be obtained by polymerizing in the presence of the chain transfer agent, or by polymerizing in a solvent containing a specific alcohol above a certain level; and , Iii) N-vinylpyrrolidone / hydroxyl group-containing (meth) acrylate copolymer has a K value of 12 or more according to the Fikencher method Unisuru it, found, it had completed the present invention.

Therefore, the first vinylpyrrolidone-based copolymer according to the present invention comprises a structural unit (A) derived from N-vinylpyrrolidone and a structural unit (B) derived from a hydroxyl group-containing (meth) acrylate in a ratio relative to the total of both. When expressed, it is a vinylpyrrolidone-based copolymer containing (A) in a proportion of 50 to 95% by mass and (B) in a proportion of 50 to 5% by mass, having a K value of 12 or more according to the Fikencher method, and The water-insoluble content is 0.5% by mass (based on solid content) or less .

The second vinylpyrrolidone copolymer according to the present invention is characterized in that, in the first vinylpyrrolidone copolymer, the degree of dispersion is 1.8 or less.
Next, the first method for producing a vinylpyrrolidone-based copolymer according to the present invention is the above when the N-vinylpyrrolidone (a) and the hydroxyl group-containing (meth) acrylate (b) are represented by a ratio to the total. In polymerizing the monomer component that (a) is 50 to 95% by mass and (b) is 50 to 5% by mass, an azo polymerization initiator is used, and 0% relative to the monomer component is used. Polymerization is performed in the presence of 0.01% by mass or more of a chain transfer agent. In the production method, a particularly preferred embodiment is an embodiment using a mercapto compound as the chain transfer agent.

And the manufacturing method of the 2nd vinylpyrrolidone-type copolymer concerning this invention is the said (when N-vinylpyrrolidone (a) and a hydroxyl-containing (meth) acrylate (b) are represented by the ratio with respect to both total ( When polymerizing the monomer component which a) is 50-95 mass% and said (b) contains in the ratio of 50-5 mass%, while using an azo polymerization initiator, C1-C5 alcohol is 10 Polymerization is carried out in a solvent containing at least mass% (ratio to the total amount of solvent).

  According to the present invention, a vinylpyrrolidone-based copolymer that can achieve a low water-insoluble content and / or a low dispersity while having N-vinylpyrrolidone and a hydroxyl group-containing (meth) acrylate as essential components, that is, Thus, a copolymer of N-vinylpyrrolidone and a hydroxyl group-containing (meth) acrylate that can give a good crosslinked coating film can be easily obtained.

Hereinafter, the vinylpyrrolidone copolymer and the production method thereof according to the present invention will be described in detail. However, the scope of the present invention is not limited to these explanations, and the gist of the present invention is not limited to the following examples. Changes can be made as appropriate without departing from the scope.
[Vinyl pyrrolidone copolymer]
Vinylpyrrolidone copolymer (first contact and the second vinyl pyrrolidone copolymers.; The same applies hereinafter if simply referred to as "vinylpyrrolidone copolymer of the present invention") of the present invention, N -When the structural unit (A) derived from vinylpyrrolidone and the structural unit (B) derived from a hydroxyl group-containing (meth) acrylate are expressed in a ratio relative to the total, (A) is 50 to 95% by mass, (B) Is contained at a ratio of 50 to 5% by mass. Preferably, the (A) is 60 to 90% by mass, the (B) is 40 to 10% by mass, more preferably the (A) is 65 to 85% by mass, and the (B) is 35 to 15%. % By mass. If the mutual ratio (copolymerization ratio) of the structural unit (A) derived from N-vinylpyrrolidone and the structural unit (B) derived from a hydroxyl group-containing (meth) acrylate is within the above range, for example, it has both water resistance and hydrophilicity. Therefore, it can be a copolymer suitable for obtaining a good crosslinked film. When the structural unit (A) derived from N-vinylpyrrolidone is larger than the above range (when the structural unit (B) derived from a hydroxyl group-containing (meth) acrylate is smaller than the above range), the reactivity with the crosslinking agent is high. Advantages derived from a hydroxyl group-containing (meth) acrylate are less likely to be expressed, and conversely, when the number of structural units (A) derived from N-vinylpyrrolidone is less than the above range (a structural unit derived from a hydroxyl group-containing (meth) acrylate (B ) Is larger than the above range), gelation tends to occur, resulting in a copolymer having a large amount of water insolubles, or a copolymer having a high degree of dispersion (wide molecular weight distribution).

The vinylpyrrolidone-based copolymer of the present invention includes a structural unit (A) derived from N-vinylpyrrolidone and a structural unit (B) derived from a hydroxyl group-containing (meth) acrylate [a method for producing a vinylpyrrolidone-based copolymer ] May have a structural unit derived from a monomer (other monomer) copolymerizable with N-vinylpyrrolidone described later in the section. When it also has structural units derived from other monomers, the proportion of structural units derived from other monomers is preferably less than 20% by mass relative to the total structural units, and less than 10% by mass. More preferably.
In the above configuration, the first vinylpyrrolidone-based copolymer of the present invention has a water-insoluble content of 0.5% by mass or less based on the solid content (that is, the water-insoluble content content based on the solid content is 0.5% or less). Mass% or less). Preferably it is 0.3 mass% or less, More preferably, it is 0.1 mass% or less. Thus, if the water-insoluble content on a solid basis is 0.5% by mass or less, for example, when the film is formed and crosslinked, the surface smoothness of the formed crosslinked coating film is deteriorated. Or the problem that the gel swells when it is washed with water to remove unreacted raw materials after crosslinking can be avoided. In addition, the water-insoluble content rate of the copolymer on a solid content basis is measured by the method described later in Examples.

The first vinylpyrrolidone copolymer of the present invention can be easily obtained by the method for producing the first or second vinylpyrrolidone copolymer of the present invention described later, but is not limited thereto. is not.
The second vinylpyrrolidone copolymer of the present invention has a dispersity of 1.8 or less, preferably 1.75 or less, more preferably 1.70 or less. Thus, when the degree of dispersion is 1.8 or less, for example, when the film is formed and crosslinked, the problem that the uniformity of the formed crosslinked coating film deteriorates can be avoided. . The dispersity is a parameter determined by weight average molecular weight / number average molecular weight, and can be measured by the method described later in Examples.

The second vinylpyrrolidone-based copolymer of the present invention is a method using a mercapto compound as a chain transfer agent in the process for producing the first vinylpyrrolidone-based copolymer of the present invention described later (particularly preferred embodiment described above). Or is easily obtained by the method for producing the second vinylpyrrolidone copolymer of the present invention described later, but is not limited thereto.
The second vinylpyrrolidone-based copolymer of the present invention has a water-insoluble content of 0.5% by mass (based on solid content) or less and a dispersity of 1.8 or less. That is, the second vinylpyrrolidone copolymer of the present invention, the requirements of the first vinylpyrrolidone copolymer of the present invention described above requirements (degree of dispersion) described above (the water-insoluble fraction content) Can be said to be the most preferable aspect of the present invention. Here, regarding the water-insoluble component and the degree of dispersion, the above-described explanations can be applied similarly.

  In the vinylpyrrolidone-based copolymer of the present invention and the production method thereof described later, as the hydroxyl group-containing (meth) acrylate (b) that provides the structural unit (B), 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) Acrylate, hydroxybutyl (meth) acrylate, 2-hydroxyethoxyethyl (meth) acrylate, and the like are mentioned. Among them, from the viewpoint of reactivity with the crosslinking agent and water resistance of the crosslinked coating film, 2-hydroxyethyl ( (Meth) acrylate is preferred. The 2-hydroxyethyl (meth) acrylate may be 2-hydroxyethyl methacrylate (HEMA), but 2-hydroxyethyl acrylate (HEA) is more preferable. Since 2-hydroxyethyl acrylate (HEA) has high hydrophilicity, it increases the hydrophilicity of the crosslinked coating film obtained from the vinylpyrrolidone-based copolymer using this as a raw material monomer, and improves the water washability of the uncrosslinked portion. This is because, since the crosslinking reactivity is good, the reactivity between the vinylpyrrolidone copolymer and the crosslinking agent is increased.

The vinyl pyrrolidone copolymer of the present invention is required to have a K value of 12 or more as determined by the Fikencher method, preferably 15 or more, and more preferably 20 or more. This is because when the K value is less than 12, water resistance tends to decrease when a crosslinked coating film is formed. The upper limit of the K value in the vinylpyrrolidone copolymer of the present invention is not questioned, but it is preferably 90 or less, more preferably 80 or less. This is because, when the K value by the Fikencher method exceeds 90, for example, when a crosslinked coating film is used, the water-washing property after film formation tends to be insufficient.

In the present invention, the K value means that the vinylpyrrolidone copolymer is dissolved in an arbitrary solvent in which the polymer is dissolved at a concentration of 1% by mass, and the viscosity of the solution is measured at 25 ° C. with a capillary viscometer. These values are calculated using the following Fikencher equation.
(Logη _rel) / C = ^{_{[(75K 0 2) / (1}} + 1.5K 0 C) ] + _{K 0}
K = 1000K ₀
However, C shows the g number of the vinylpyrrolidone-type copolymer in 100 mL of solutions, and (eta) _rel shows the viscosity of the solution with respect to a solvent.
The use of the vinylpyrrolidone-based copolymer of the present invention is not limited, and can be used for any application. An example of its use is various inorganic and organic dispersants, flocculants, thickeners, pressure-sensitive adhesives, adhesives, surface coating agents, crosslinkable compositions, and more specifically, mud dispersants. , Cement material dispersant, thickener for cement material, builder for detergent, anti-transfer agent for detergent, heavy metal supplement, metal surface treatment agent, dyeing assistant, dye fixing agent, foam stabilizer, emulsion stabilizer, ink Dye dispersants, water-based ink stabilizers, paint content dispersants, paint thickeners, pressure sensitive adhesives, paper adhesives, stick glues, medical adhesives, adhesives for patches, adhesives for cosmetic packs, resins Filler dispersant, recording paper coating agent, inkjet paper surface treatment agent, photosensitive resin dispersant, antistatic agent, moisturizer, water absorbent resin raw material, fertilizer binder, polymer cross-linking agent, resin compatibilizer Agent, photographic additive, makeup Preparations, hair styling aids, hair spray additives, sunscreen composition additives, etc. The raw material polymer of the curable resin composition which can be obtained is mentioned, and it is utilized as a crosslinked coating film.

[Method for producing vinylpyrrolidone copolymer]
Production method of vinylpyrrolidone copolymer of the present invention (first and second methods of producing vinylpyrrolidone copolymer; hereinafter referred to simply as “production method of vinylpyrrolidone copolymer of the present invention”) The same applies to the case where N-vinylpyrrolidone (a) and the hydroxyl group-containing (meth) acrylate (b) are expressed in a ratio to the total of both, and (a) is 50 to 95% by mass, (b) Polymerizes the monomer component contained at a ratio of 50 to 5% by mass. Preferably, the (a) is 60 to 90% by mass, the (b) is 40 to 10% by mass, more preferably the (a) is 65 to 85% by mass, and the (b) is 35 to 15%. % By mass. If the mutual ratio of N-vinylpyrrolidone (a) and the hydroxyl group-containing (meth) acrylate (b) is in the above range, a copolymer having a small amount of water insolubles (in the range described later) can be obtained. When the N-vinylpyrrolidone (a) is more than the above range (when the hydroxyl group-containing (meth) acrylate (b) is less than the above range), the resulting copolymer has a high hydroxyl group reactivity with a crosslinking agent. Advantages derived from (meth) acrylate are less likely to be expressed, and conversely, when N-vinylpyrrolidone (a) is less than the above range (when hydroxyl group-containing (meth) acrylate (b) is more than the above range), Gelation is likely to occur, and the resulting copolymer may have a large amount of water-insoluble matter, or the resulting copolymer may have a high degree of dispersion (wide molecular weight distribution).

  The monomer component essentially comprises N-vinylpyrrolidone (a) and a hydroxyl group-containing (meth) acrylate (b), but in addition, a monomer copolymerizable with N-vinylpyrrolidone (others) The monomer) may also be included. Other monomers are not particularly limited, and specifically, for example, 1) methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth) acrylic acid (Meth) acrylic acid esters such as cyclohexyl; 2) (meth) acrylamides such as (meth) acrylamide and N-monomethyl (meth) acrylamide, N-monoethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide Acrylamide derivatives; 3) Basic unsaturated monomers such as dimethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylamide, vinylpyridine, vinylimidazole; 4) Vinylformamide, vinylacetamide, vinyloxazolidone, etc. Vinylamides; 5) (meth) acrylic acid, itaconic acid, male Carboxyl group-containing unsaturated monomers such as acid and fumaric acid; 6) unsaturated acid anhydrides such as maleic anhydride and itaconic anhydride; 7) vinyl esters such as vinyl propionate and vinyl acetate; 8) 9) styrene and its derivatives; 10) ethyl (meth) acrylic acid-2-sulfonate and its derivatives; 11) vinyl sulfonic acid and its derivatives; 12) methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether 13) Olefins such as ethylene, propylene, octene and butadiene; and the like. Among these monomers, 1) to 8) are particularly preferable from the viewpoint of copolymerization with N-vinylpyrrolidone. The other monomer may be only one kind or two or more kinds. When the monomer component also contains the other monomer, the content of the other monomer is preferably less than 20% by mass with respect to the total monomer component. More preferably, it is less than%.

  In the first method for producing a vinylpyrrolidone copolymer of the present invention, it is important to perform polymerization in the presence of 0.01% by mass or more of a chain transfer agent with respect to the monomer component. Thereby, a copolymer with little water-insoluble content can be obtained. Similarly, in the method for producing the second vinylpyrrolidone copolymer of the present invention, it is of course preferable that 0.01% by mass or more of a chain transfer agent is used with respect to the monomer component. It is. As will be described later, when the chain transfer agent is added sequentially, the chain transfer agent is in the above range with respect to the monomer component at any point during the polymerization (in other words, the polymerization The chain transfer agent present in the reaction system at each time point is within the above range with respect to the monomer component present in the reaction system at that time). Good.

Preferred examples of the chain transfer agent include mercapto compounds, hypophosphorous acid and salts thereof, bisulfite, bisulfite and the like. Among these, mercapto compounds, hypophosphorous acid and salts thereof are more preferable. Only one type of chain transfer agent may be used, or two or more types may be used.
The embodiment using a mercapto compound as the chain transfer agent is a particularly preferable embodiment in the method for producing the first vinylpyrrolidone-based copolymer of the present invention in that a copolymer having a low degree of dispersion can be easily obtained. Thereby, the second vinylpyrrolidone copolymer of the present invention described above can be easily obtained.

Examples of mercapto compounds that can be preferably used as the chain transfer agent include mercapto alcohols such as 2-mercaptoethanol, 1,3-mercaptopropanol and 1-thioglycerol, 3-mercaptopropionic acid, mercaptosuccinic acid, mercaptoacetic acid and the like. Examples include mercaptocarboxylic acid and salts thereof, ethyl-2-mercaptoacetate, cysteine, and n-dodecyl mercaptan. Among these, mercapto alcohol is preferable, and 2-mercaptoethanol is more preferable.
The amount of the chain transfer agent used may be 0.01% by mass or more with respect to the monomer component, but preferably 0.05 to 5% by mass with respect to the monomer component. .

  In the method for producing the second vinylpyrrolidone-based copolymer of the present invention, a solvent (hereinafter referred to as “specific solvent”) containing 10% by mass (ratio to the total amount of solvent) of an alcohol having 1 to 5 carbon atoms. It is important to carry out the polymerization in Thereby, a copolymer with little water-insoluble content and low dispersibility can be obtained. Similarly, in the method for producing the first vinylpyrrolidone-based copolymer of the present invention, it is of course preferable that the polymerization is performed in the specific solvent. As will be described later, when the solvent is added sequentially, the specific solvent is in the above range with respect to the total amount of the solvent at any point during the polymerization (in other words, the polymerization is performed). The specific solvent present in the reaction system at each time point may be within the above range with respect to the total amount of the solvent present in the reaction system at each time point).

Examples of the alcohol having 1 to 5 carbon atoms include methyl alcohol, ethyl alcohol, isopropyl alcohol, and 2-methyl-1-propanol. Only 1 type may be sufficient as the said C1-C5 alcohol, and 2 or more types may be sufficient as it.
The alcohol having 1 to 5 carbon atoms may be contained in an amount of 10% by mass or more (in other words, 10% by mass or more in the specific solvent) with respect to the total amount of the solvent, preferably 15% by mass or more, and more preferably 20%. It is contained by mass% or more.
As a preferable aspect as the said specific solvent, the mixed solvent of the said C1-C5 alcohol and water is mentioned, for example. The content of water is preferably 30% by mass or more, and more preferably 50% by mass or more. If the water in the specific solvent is less than 30%, the reaction of N-vinylpyrrolidone during polymerization tends to be slow.

When the specific solvent also contains a solvent (other solvent) other than the alcohol having 1 to 5 carbon atoms, the other solvent is preferably water (the first vinylpyrrolidone copolymer of the present invention). In the production method, when a specific solvent containing a specific amount of the alcohol having 1 to 5 carbon atoms is not used, the polymerization is preferably performed in a solvent containing water as a main component. Of course, the specific solvent or the solvent in the method for producing the first vinylpyrrolidone-based copolymer of the present invention may contain a solvent other than water. It is desirable to be within the range of% or less.
Examples of the solvent other than water include alcohols having 6 or more carbon atoms such as 1-heptanol; ethers (acetates) of alkylene glycol such as propylene glycol monomethyl acetate and diethylene glycol monomethyl ether acetate; dimethylformamide, N-methyl Amides such as pyrrolidone; Esters such as ethyl acetate, butyl acetate and γ-butyrolactone; Aliphatic hydrocarbons such as hexane and octane; Cycloaliphatic saturated hydrocarbons such as cyclohexane; Cyclohexene and other cycloaliphatic unsaturations Hydrocarbons; aromatic hydrocarbons such as benzene, toluene and xylene; ketones such as acetone and methyl ethyl ketone; halogenated hydrocarbons such as dichloroethane, chloroform and carbon tetrachloride; diethyl ether, dioxane and tetrahydrofuran Sulfonic acid esters such as dimethyl sulfoxide; dimethyl carbonate, carbonic esters such as diethyl carbonate; ethers etc. ethylene carbonate, cycloaliphatic carbonates such as propylene carbonate; and the like.

The amount of the specific solvent used and the amount of the solvent used in the method for producing the first vinylpyrrolidone copolymer of the present invention are not particularly limited, and may be appropriately set in consideration of productivity and the like. However, it is preferable that the concentration of the monomer component is 10% by mass or more.
In the method for producing the vinylpyrrolidone-based copolymer of the present invention, a conventionally known polymerization initiator can be used. Examples of the polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylpropionamidine) dihydrochloride, dimethyl-2,2′-azobisisobutyrate. Azo polymerization initiators such as 4,4′-azobis (4-cyanovaleric acid); radical polymerization polymerization initiators such as peroxides such as benzoyl peroxide and hydrogen peroxide; boron trifluoride or its And a cationic polymerization initiator such as a complex, iron (II) chloride, diethylaluminum chloride, diethylzinc, heteropolyacid, activated clay, and the like. Among these, an azo polymerization initiator is preferable from the viewpoint of polymerization efficiency, and dimethyl-2,2′-azobisisobutyrate is particularly preferable. Only one polymerization initiator may be used, or two or more polymerization initiators may be used.

The amount of the polymerization initiator used is not particularly limited, but is preferably 0.05% by mass or more based on the monomer component. More preferably, it is good to set it as 0.1 mass% or more with respect to a monomer component. If the amount of the polymerization initiator used is less than 0.05% by mass, a large amount of unreacted monomer may remain.
In the method for producing a vinylpyrrolidone copolymer of the present invention, any promoter, pH adjuster, buffering agent, and the like can be used as necessary together with the polymerization initiator.
In the method for producing a vinylpyrrolidone-based copolymer of the present invention, there are no particular restrictions on the preparation method of the monomer component, polymerization initiator, solvent (specific solvent), chain transfer agent, etc. Regarding the components, the hydroxyl group-containing (meth) acrylate (b) is preferably added to the reactor by sequential addition. When the hydroxyl group-containing (meth) acrylate (b) is added all at once rather than sequentially, a large amount of water-insoluble matter may be generated. Specifically, the sequential addition may be continuous addition (for example, an aspect of dropping over a certain period of time), or intermittent addition (for example, an aspect in which the raw material is divided into a plurality of times. ) Or a combination of both.

In the first and second vinylpyrrolidone-based copolymer production methods of the present invention, the polymerization temperature (temperature of the reaction solution) during the polymerization is preferably 50 ° C. or higher, and preferably 60 ° C. or higher. It is more preferable.
In the method for producing a vinylpyrrolidone-based copolymer of the present invention, an unreacted hydroxyl group-containing (meth) acrylate and a component other than water (such as alcohol) in the solvent by subjecting the reaction solution obtained by the polymerization to distillation. ) May be removed to obtain an aqueous solution.
The vinylpyrrolidone-based copolymer of the present invention has a K value of 12 or more according to the Fikencher formula as described above. However, if the K value is increased, the water-insoluble content tends to increase and the molecular weight distribution also widens. Although it is easy, according to the manufacturing method of the present invention described above, such a problem hardly occurs.

  When the hydroxyl group-containing (meth) acrylate which is one of the raw material monomers for obtaining the vinylpyrrolidone-based copolymer of the present invention is 2-hydroxyethyl (meth) acrylate, from 2-hydroxyethyl methacrylate (HEMA) As described above, it is preferable to use 2-hydroxyethyl acrylate (HEA). This is because 2-hydroxyethyl acrylate (HEA) has high cross-linking reactivity, and therefore increases the cross-linking reactivity of the vinylpyrrolidone-based copolymer using this as a raw material monomer. However, 2-hydroxyethyl acrylate (HEA) is more susceptible to a crosslinking reaction during the polymerization to obtain a vinylpyrrolidone-based copolymer, and therefore usually a copolymer having a small water-insoluble content and a narrow molecular weight distribution. Although it is difficult to obtain a polymer, the above-described production method of the present invention can overcome such difficulty when 2-hydroxyethyl acrylate (HEA) is used as a raw material monomer.

Hereinafter, the present invention will be described more specifically by way of examples. However, the present invention is not limited to these examples. Hereinafter, unless otherwise specified, “part by mass” is simply referred to as “part”, and “mass%” is simply referred to as “%”.
In Examples and Comparative Examples, the water-insoluble content and the degree of dispersion were measured as follows.
<Water insoluble content>
A vinylpyrrolidone copolymer solution 500 g (polymer solid content 50 g) adjusted to a concentration of 10% was filtered through a sieve (nominal size 45 μm, diameter 75 mm, depth 20 mm) according to JIS-Z8801, and remained on the sieve. The gel is washed with 1000 g of ion exchange water. After drying this sieve at 80 ° C. for 1 hour, its weight is measured to determine the weight increase (Xg) before and after filtration, and the water-insoluble content is calculated based on the following formula.

Water-insoluble content (%) = [weight increase (Xg) / polymer solid content (50 g)] × 100
<Dispersity>
The obtained vinylpyrrolidone copolymer solution is analyzed by gel permeation chromatography (GPC) under the following conditions to obtain a weight average molecular weight (Mw) and a number average molecular weight (Mn) in terms of polystyrene. The degree of dispersion is calculated according to (Mw) / (Mn).
Column: “Shodex KD-G”, “Shodex LF804”, “Shodex KD801” manufactured by Showa Denko KK
Eluent: 0.1% lithium bromide-containing dimethylformamide solution Eluent flow rate: 0.8 mL / min Injection volume: 10 μL
Column oven: 40 ° C
Detector: Differential refractometer (RI)
Sample concentration: 0.5%
Example 1
70 parts of ion-exchanged water was added to a polymerization vessel equipped with a cooling pipe, a nitrogen introduction line, and a thermometer, and nitrogen was introduced while stirring to create a nitrogen atmosphere. After heating the polymerization vessel in an oil bath to an internal temperature of 98 ° C., 33.7 parts of N-vinylpyrrolidone (NVP), 7.9 parts of 2-hydroxyethyl acrylate (HEA), 25% aqueous ammonia 0.5% Part, 30% hypophosphorous acid aqueous solution 1.26 parts, ion-exchanged water 7.2 parts monomer solution (A1), 4,4′-azobis-4-cyanovaleric acid (manufactured by Niho Chemical Co., Ltd. “ NC25 ") 0.24 part, 0.26 part of triethanolamine, and 17.6 parts of ion-exchanged water were continuously added dropwise to the initiator solution (A1) over 1 hour. Subsequently, a monomer solution (B1) obtained by dissolving 0.5 part of 2-hydroxyethyl acrylate (HEA) in 2.6 parts of ion-exchanged water was added over 15 minutes. Furthermore, while continuing heating and stirring for 105 minutes, 0.07 part of 4,4′-azobis-4-cyanovaleric acid (“NC25” manufactured by Niho Chemical Co., Ltd.) in 3 parts of ion-exchanged water, 0.08 of triethanolamine The initiator solution (B1) in which the part was dissolved was added in three portions to obtain an NVP / HEA copolymer solution (colorless and transparent, solid content 30.1%).

The NVP / HEA copolymer in the resulting solution has a K value of 28.0, a water insoluble content of 0.09%, a weight average molecular weight of 77,640, a number average molecular weight of 38,969, and a degree of dispersion. Was 1.99.
(Example 2)
In Example 1, in place of the monomer solution (A1), 29.5 parts of N-vinylpyrrolidone (NVP), 11.9 parts of 2-hydroxyethyl acrylate (HEA), 0.5 part of 25% aqueous ammonia, 30% It changed so that the monomer solution (A2) which mixed 1.26 parts of hypophosphorous acid aqueous solution and 7.2 parts of ion-exchange water might be used, it replaced with a monomer solution (B1), and 2 parts of ion-exchange water was 2 -A solution of NVP / HEA copolymer (colorless and transparent, similar to Example 1) except that the monomer solution (B2) in which 0.76 part of hydroxyethyl acrylate (HEA) was dissolved was used. 29.9% solids) was obtained.

The NVP / HEA copolymer in the resulting solution has a K value of 26.2, a water insoluble content of 0.11%, a weight average molecular weight of 75,832, a number average molecular weight of 41,883, and a degree of dispersion. Was 1.81.
(Example 3)
A solution of NVP / HEMA copolymer in the same manner as in Example 1 except that in Example 1, 2-hydroxyethyl acrylate (HEA) was used instead of 2-hydroxyethyl methacrylate (HEMA). (Clear and colorless, solid content 29.5%) was obtained.
The NVP / HEA copolymer in the resulting solution had a K value of 28.5, a water-insoluble content of 0.08%, a weight average molecular weight of 82,286, a number average molecular weight of 45,329, and a degree of dispersion. Was 1.82.

Example 4
50 parts of ion-exchanged water was added to a polymerization vessel equipped with a cooling pipe, a nitrogen introduction line, and a thermometer, and nitrogen was introduced while stirring to create a nitrogen atmosphere. After heating the polymerization vessel in an oil bath to an internal temperature of 90 ° C., 33.6 parts of N-vinylpyrrolidone (NVP), 7.9 parts of 2-hydroxyethyl acrylate (HEA), 0.13 of 2-mercaptoethanol Part, monomer solution (A4) mixed with 34 parts of ion-exchanged water, 0.42 part of dimethyl-2,2′-azobisisobutyrate (“V601” manufactured by Wako Pure Chemical Industries, Ltd.), 2.3 parts of isopropyl alcohol The initiator solution (A4) in which 1.5 parts of ion-exchanged water was mixed and dissolved was continuously added dropwise over 1 hour. Subsequently, a monomer solution (B4) in which 0.5 part of 2-hydroxyethyl acrylate (HEA) was dissolved in 9.6 parts of ion-exchanged water was added over 15 minutes. Further, while heating and stirring was continued for 135 minutes, 0.3 part of ion-exchanged water and 0.45 part of isopropyl alcohol were added to dimethyl-2,2′-azobisisobutyrate (“V601” manufactured by Wako Pure Chemical Industries). The initiator solution (B4) in which 08 parts were dissolved was added in 4 portions to obtain a solution of NVP / HEA copolymer (colorless and transparent, solid content 30.1%).

The NVP / HEA copolymer in the resulting solution has a K value of 30.0, a water-insoluble content of 0.00%, a weight average molecular weight of 93,316, a number average molecular weight of 59,364, and a degree of dispersion. Was 1.57.
(Example 5)
10 parts of ion exchange water and 10 parts of ethyl alcohol were added to a polymerization vessel equipped with a cooling pipe, a nitrogen introduction line, and a thermometer, and nitrogen was introduced while stirring to create a nitrogen atmosphere. After heating the polymerization vessel in an oil bath to an internal temperature of 80 ° C., 16.8 parts of N-vinylpyrrolidone (NVP), 4.2 parts of 2-hydroxyethyl acrylate (HEA), 11 parts of ion-exchanged water, ethyl Monomer solution (A5) mixed with 11 parts of alcohol, 0.21 part of dimethyl-2,2′-azobisisobutyrate (“V601” manufactured by Wako Pure Chemical Industries, Ltd.), 3.4 parts of ethyl alcohol, ion-exchanged water An initiator solution (A5) in which 3.4 parts were mixed and dissolved was continuously added dropwise over 2 hours. Furthermore, heating and stirring were continued for 2 hours to obtain an NVP / HEA copolymer solution (colorless and transparent, solid content 31.0%).

The NVP / HEA copolymer in the resulting solution had a K value of 35.1, a water-insoluble content of 0.04%, a weight average molecular weight of 127,069, a number average molecular weight of 78,385, and a degree of dispersion. Was 1.62.
(Example 6)
17 parts of ion exchange water and 3.3 parts of ethyl alcohol were added to a polymerization vessel equipped with a cooling pipe, a nitrogen introduction line, and a thermometer, and nitrogen was introduced with stirring to form a nitrogen atmosphere. After heating the polymerization vessel in an oil bath to an internal temperature of 80 ° C., 16.8 parts of N-vinylpyrrolidone (NVP), 3.8 parts of 2-hydroxyethyl acrylate (HEA), 0.02 of 2-mercaptoethanol Part, 14.4 parts of ion-exchanged water and 6.2 parts of ethyl alcohol and dimethyl-2,2′-azobisisobutyrate (“V601” manufactured by Wako Pure Chemical Industries, Ltd.) An initiator solution (A6) in which 21 parts and 4 parts of ethyl alcohol were mixed and dissolved was continuously added dropwise over 2 hours. Subsequently, a monomer solution (B6) in which 0.42 part of 2-hydroxyethyl acrylate (HEA) was dissolved in 2.6 parts of ion-exchanged water and 1.1 parts of ethyl alcohol was added over 1 hour. Subsequently, after adding an initiator solution (B6) in which 0.02 part of dimethyl-2,2′-azobisisobutyrate (“V601” manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 0.4 part of ethyl alcohol. The internal temperature was raised to 85 ° C., and stirring was continued for 30 minutes. Next, 20 parts of ion exchange water was added, a distillation apparatus was attached, and the oil bath was heated to 125 ° C. to start distillation. When the amount of distillate reached 20 parts, 10 parts of ion-exchanged water was further added and distillation was continued. Thereafter, when 10 parts were further distilled (when the total distillate amount was 30 parts), the polymerization vessel was cooled to obtain an NVP / HEA copolymer solution. A solution (clear and colorless, solid content 30.8%) was obtained.

The NVP / HEA copolymer in the resulting solution had a K value of 34.0, a water insoluble content of 0.02%, a weight average molecular weight of 113,685, a number average molecular weight of 69,026, and a degree of dispersion. Was 1.65.
(Example 7)
17 parts of ion exchange water and 3.3 parts of ethyl alcohol were added to a polymerization vessel equipped with a cooling pipe, a nitrogen introduction line, and a thermometer, and nitrogen was introduced with stirring to form a nitrogen atmosphere. After heating the polymerization vessel in an oil bath to an internal temperature of 80 ° C., 16.8 parts of N-vinylpyrrolidone (NVP), 3.8 parts of 2-hydroxyethyl acrylate (HEA), 0.05 of 2-mercaptoethanol Part, 14.4 parts of ion-exchanged water, and 6.2 parts of ethyl alcohol and dimethyl-2,2′-azobisisobutyrate (“V601” manufactured by Wako Pure Chemical Industries, Ltd.) An initiator solution (A7) in which 21 parts and 4 parts of ethyl alcohol were mixed and dissolved was continuously added dropwise over 2 hours. Subsequently, a monomer solution (B7) in which 0.42 part of 2-hydroxyethyl acrylate (HEA) was dissolved in 2.6 parts of ion-exchanged water and 1.1 parts of ethyl alcohol was added over 1 hour, and the internal temperature The temperature was raised to 85 ° C., and stirring was continued for 30 minutes. Subsequently, an initiator solution (B7) in which 0.02 part of dimethyl-2,2′-azobisisobutyrate (“V601” manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 0.4 part of ethyl alcohol was added. The stirring was continued for another 30 minutes. Next, 20 parts of ion exchange water was added, a distillation apparatus was attached, and the oil bath was heated to 130 ° C. to start distillation. When the amount of distillate reached 20 parts, 10 parts of ion-exchanged water was further added and distillation was continued. Thereafter, when 10 parts were further distilled (when the total distillate amount was 30 parts), the polymerization vessel was cooled, and a solution of NVP / HEA copolymer (colorless and transparent, solid content 30.7%) Got.

The NVP / HEA copolymer in the resulting solution has a K value of 28.6, a water insoluble content of 0.01%, a weight average molecular weight of 76,860, a number average molecular weight of 49,837, and a degree of dispersion. Was 1.54.
(Comparative Example 1)
20 parts of ion-exchanged water was added to a polymerization vessel equipped with a cooling pipe, a nitrogen introduction line, and a thermometer, and nitrogen was introduced while stirring to create a nitrogen atmosphere. After heating the polymerization vessel in an oil bath to an internal temperature of 95 ° C., 16.8 parts of N-vinylpyrrolidone (NVP), 4.2 parts of 2-hydroxyethyl acrylate (HEA), 16.4 parts of ion-exchanged water A monomer solution (Ac1), 0.75 part of 4,4′-azobis-4-cyanovaleric acid (“NC25” manufactured by Niho Chemical Co., Ltd.), 0.76 part of triethanolamine, and ion-exchanged water 11. An initiator solution (Ac1) in which 1 part was mixed and dissolved was continuously added dropwise over 2 hours. Furthermore, heating and stirring were continued for 2 hours to obtain an NVP / HEA copolymer solution (colorless and transparent, solid content: 33.3%).

The NVP / HEA copolymer in the resulting solution has a K value of 29.7, a water insoluble content of 0.57%, a weight average molecular weight of 93,963, a number average molecular weight of 48,551, and a degree of dispersion. Was 1.94.
(Comparative Example 2)
50 parts of ion-exchanged water was added to a polymerization vessel equipped with a cooling pipe, a nitrogen introduction line, and a thermometer, and nitrogen was introduced while stirring to create a nitrogen atmosphere. After heating the polymerization vessel in an oil bath to an internal temperature of 90 ° C., 33.6 parts N-vinylpyrrolidone (NVP), 7.9 parts 2-hydroxyethyl acrylate (HEA), 27.9 parts ion-exchanged water A monomer solution (Ac2), 2.1 parts of dimethyl-2,2′-azobisisobutyrate (“V601” manufactured by Wako Pure Chemical Industries, Ltd.), 4 parts of isopropyl alcohol, and 4.4 parts of ion-exchanged water. The mixed initiator solution (Ac2) was continuously added dropwise over 1 hour. Subsequently, a monomer solution (Bc2) in which 0.5 part of 2-hydroxyethyl acrylate (HEA) was dissolved in 9.6 parts of ion-exchanged water was added over 15 minutes. Furthermore, heating and stirring were continued for 45 minutes to obtain an NVP / HEA copolymer solution (colorless and transparent, solid content 31.0%).

The NVP / HEA copolymer in the resulting solution has a K value of 31.9, a water insoluble content of 0.64%, a weight average molecular weight of 110,575, a number average molecular weight of 53,419, and a degree of dispersion. Was 2.07.
(Comparative Example 3)
50 parts of ion-exchanged water was added to a polymerization vessel equipped with a cooling pipe, a nitrogen introduction line, and a thermometer, and nitrogen was introduced while stirring to create a nitrogen atmosphere. After heating the polymerization vessel in an oil bath to an internal temperature of 90 ° C., 33.6 parts of N-vinylpyrrolidone (NVP), 7.9 parts of 2-hydroxyethyl acrylate (HEA), 32.1 parts of ion-exchanged water A monomer solution (Ac3), 1.26 parts of dimethyl-2,2′-azobisisobutyrate (“V601” manufactured by Wako Pure Chemical Industries, Ltd.), 2.4 parts of isopropyl alcohol, and 2.6 ion-exchanged water. The initiator solution (Ac3) in which the parts were mixed and dissolved was continuously added dropwise over 1 hour. Subsequently, a monomer solution (Bc3) in which 0.5 part of 2-hydroxyethyl acrylate (HEA) was dissolved in 9.6 parts of ion-exchanged water was added over 15 minutes. Further, while continuing heating and stirring for 105 minutes, 0.13 part of ion exchange water, 0.12 part of isopropyl alcohol and dimethyl-2,2′-azobisisobutyrate (“V601” manufactured by Wako Pure Chemical Industries, Ltd.) The initiator solution (Bc3) in which 06 parts were dissolved was added in three portions to obtain an NVP / HEA copolymer solution (colorless and transparent, solid content 31.0%).

  The NVP / HEA copolymer in the resulting solution has a K value of 37.3, a water-insoluble content of 1.03%, a weight average molecular weight of 158,628, a number average molecular weight of 75,975, and a degree of dispersion. Was 2.09.

  The vinylpyrrolidone-based copolymer according to the present invention can be suitably used as a raw material polymer for a curable resin composition for obtaining a film having both water resistance and hydrophilicity, for example.

Claims (7)

When the structural unit (A) derived from N-vinylpyrrolidone and the structural unit (B) derived from a hydroxyl group-containing (meth) acrylate are expressed in a ratio to the total, (A) is 50 to 95% by mass, (B ) Is a vinylpyrrolidone-based copolymer contained in a proportion of 50 to 5% by mass, having a K value of 12 or more by the Fikencher method and a water-insoluble content of 0.5% by mass (based on solid content) or less. there, wherein the vinyl pyrrolidone type copolymer. Min plastid is 1.8 or less, the vinyl pyrrolidone type copolymer according to claim 1. The vinylpyrrolidone according to claim 1 or 2 , wherein the structural unit (A) derived from N-vinylpyrrolidone and the structural unit (B) derived from a hydroxyl group-containing (meth) acrylate occupy 80% by mass or more of all structural units. Copolymer. When the N-vinylpyrrolidone (a) and the hydroxyl group-containing (meth) acrylate (b) are expressed in a ratio to the total, the (a) is 50 to 95% by mass, and the (b) is 50 to 5% by mass. In polymerizing the monomer component contained in a proportion, an azo polymerization initiator is used and polymerization is performed in the presence of a chain transfer agent of 0.01% by mass or more based on the monomer component. A method for producing a polymer. The method for producing a vinylpyrrolidone-based copolymer according to claim 4 , wherein a mercapto compound is used as the chain transfer agent. When the N-vinylpyrrolidone (a) and the hydroxyl group-containing (meth) acrylate (b) are expressed in a ratio to the total, the (a) is 50 to 95% by mass, and the (b) is 50 to 5% by mass. A vinyl pyrrolidone which is polymerized in a solvent containing an azo polymerization initiator and containing 10% by mass or more of an alcohol having 1 to 5 carbon atoms (ratio to the total amount of the solvent) in polymerizing the monomer component contained in a proportion. A method for producing a copolymer. The vinylpyrrolidone-based copolymer according to any one of claims 4 to 6 , wherein the N-vinylpyrrolidone and the hydroxyl group-containing (meth) acrylate occupy 80% by mass or more in the monomer component to be polymerized. Manufacturing method.