Monomer composition comprising phosphate group-containing (METH)acrylate

Abstract

To provide a monomer composition used to introduce a phosphate group-containing (meth)acrylate unit into a copolymer and in a copolymer solution obtained by subjecting a phosphate group-containing (meth)acrylate and other monomers to solution polymerization, capable of suppressing an increase in viscosity and the generation of precipitates and generating a copolymer having improved adhesion to a metal by increasing the copolymerization ratio of the phosphate group-containing (meth)acrylate subjected to solution polymerization.SOLUTION: There is provided a monomer composition comprising a phosphate group-containing (meth)acrylate (A) having a specific structure and a pyrophosphate group-containing di(meth)acrylate (B) having a specific structure, wherein the content of the phosphate group-containing (meth)acrylate (A) is 94 to 99.99 mass% and the content of the pyrophosphate group-containing di(meth)acrylate (B) is 0.01 to 5 mass% based on 100 mass% of the monomer composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a monomer composition containing a phosphate group-containing (meth)acrylate as a main component.

Background Art

[0002] By using a phosphate group-containing (meth)acrylate as a copolymerization component, acidity and hydrophilicity can be imparted to the copolymer. In the obtained copolymer, the acidity and hydrophilicity can be adjusted by neutralizing a part of the phosphate groups with a base such as sodium hydroxide. Therefore, the phosphate group-containing (meth)acrylate or the copolymer obtained using the same is suitably used in applications where adjustment of acidity or hydrophilicity is required, such as adhesives or aqueous paints. For example, Patent Document 1 discloses a dental composition containing a phosphate group-containing alkylene (meth)acrylate and a phosphate group-containing polyoxyalkylene (meth)acrylate, and it is described that the dental composition exhibits high adhesiveness even to dentin where carious parts are present. Patent Document 2 discloses an aqueous resin composition containing a copolymer of four specific radically polymerizable monomers including a phosphate group-containing (meth)acrylate, and it is described that by using the aqueous resin composition, a coating film excellent in adhesiveness and rust prevention properties to a substrate with poor adhesiveness such as metal can be obtained.

[0003] As a general method for preventing gelation during the polymerization of (meth)acrylate monomers, a method of adding a polymerization inhibitor is known. As polymerization inhibitors for (meth)acrylate monomers, for example, phenolic compounds such as hydroquinone (Patent Document 3), nitroso compounds (Patent Document 4), or phenothiazine compounds (Patent Document 5) are used.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] However, when solution polymerization is carried out using a phosphate group-containing (meth)acrylate as a copolymerization component, the higher the content ratio of the phosphate group-containing (meth)acrylate, the higher the viscosity of the resulting copolymer solution, and there are problems such as a decrease in transparency due to the generation of precipitates. This is presumably because crosslinking proceeds due to the condensation reaction between phosphate groups, and the polymerization inhibitors described in Patent Documents 3 to 5 cannot suppress this crosslinking reaction. Therefore, although improving acidity and hydrophilicity is expected by introducing many phosphate groups into the copolymer, due to the above problems, it is difficult to increase the content ratio of the phosphate group-containing (meth)acrylate, so it is difficult to sufficiently impart acidity and hydrophilicity to the resulting copolymer. When a coating film with insufficient acidity or hydrophilicity is formed on a metal substrate such as iron, aluminum, or copper, the adhesion between the coating film and the substrate becomes insufficient, and the coating film is likely to peel off. In addition, the generation of precipitates in the copolymer solution is likely to occur even when the hydrophilicity of the copolymer is insufficient. This is because the lower the hydrophilicity of the copolymer, the more likely the solvent solubility is to decrease. A copolymer solution with reduced transparency due to the generation of precipitates has problems such as poor coatability or poor appearance due to reduced transparency.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is a monomer composition used for introducing a phosphate group-containing (meth) acrylate unit into a copolymer, in a copolymer solution obtained by subjecting a phosphate group-containing (meth) acrylate and other monomers to solution polymerization, it is possible to suppress an increase in viscosity and the generation of precipitates, and further, by increasing the copolymerization ratio of the phosphate group-containing (meth) acrylate to be subjected to solution polymerization, it is possible to produce a copolymer having improved adhesion to a metal, and to provide a monomer composition.

Means for Solving the Problems

[0007] As a result of intensive studies by the present inventors, when a phosphate group-containing (meth) acrylate having a specific structure is used as a copolymerization component and a small amount of a diphosphate group-containing di (meth) acrylate having a specific structure is mixed, in a copolymer solution obtained by subjecting the phosphate group-containing (meth) acrylate and other monomers to solution polymerization, an increase in viscosity and the generation of precipitates are suppressed, whereby the copolymerization ratio of the phosphate group-containing (meth) acrylate can be increased, and it has been found that a copolymer having high acidity and hydrophilicity can be obtained, and the present invention has been completed.

[0008] That is, the monomer composition of the present invention is a monomer composition containing a phosphate group-containing (meth) acrylate (A) represented by the general formula (1) described later and a diphosphate group-containing di (meth) acrylate (B) represented by the general formula (2) described later. The content of the phosphate group-containing (meth) acrylate (A) is 94 to 99.99% by mass, and the content of the diphosphate group-containing di (meth) acrylate (B) is 0.01 to 5% by mass with respect to 100% by mass of the monomer composition.

Effects of the Invention

[0009] According to the present invention, there is provided a monomer composition used for introducing a phosphate group-containing (meth)acrylate unit into a copolymer. In a copolymer solution obtained by subjecting a phosphate group-containing (meth)acrylate and other monomers to solution polymerization, an increase in viscosity and the generation of precipitates can be suppressed. Furthermore, by increasing the copolymerization ratio of the phosphate group-containing (meth)acrylate subjected to solution polymerization, a copolymer with improved adhesion to a metal can be produced.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, after explaining each component contained in the monomer composition of the present invention, the monomer composition of the present invention and its production method, further, a polymerizable composition containing the monomer composition of the present invention, a copolymer and a copolymer solution obtained using the monomer composition of the present invention will be explained. In the present invention, (meth)acrylate means at least one selected from acrylate and methacrylate, (meth)acrylic means at least one selected from acrylic and methacrylic, and (meth)acryloyl means at least one selected from acryloyl and methacryloyl. In the present invention, a numerical range defined using the symbol "~" includes the numerical values at both ends (upper limit and lower limit) of "~". For example, "2~10" represents a range of 2 or more and 10 or less.

[0011] <Phosphate Group-Containing (Meth)Acrylate (A)> The phosphate group-containing (meth)acrylate (A) used in the present invention is a compound represented by the following general formula (1).

[0012]

Chemical formula

[0013] R in the general formula (1) 1 is a hydrogen atom or a methyl group, and can be appropriately selected in consideration of reactivity with other monomers to be copolymerized and the like. R in the general formula (1) 2 is a linear or branched alkylene group having 1 to 6 carbon atoms, and is not particularly limited. However, from the viewpoint of suppressing an increase in viscosity and generation of precipitates in the obtained copolymer solution, the number of carbon atoms is preferably 2 to 5, more preferably 3 to 4. R 2 is preferably an ethylene group, a propylene group or a tetramethylene group from the viewpoint of easy availability. Among these, from the viewpoint of solubility of the obtained copolymer in an organic solvent, an ethylene group or a propylene group is more preferable, while from the viewpoint of flexibility of the obtained copolymer, a tetramethylene group is more preferable. n in the general formula (1) represents the average number of added moles, and may be 1 to 50 and is not particularly limited. However, from the viewpoint of improving the solubility of the obtained copolymer in an organic solvent, suppressing an increase in viscosity and generation of precipitates in the obtained copolymer solution, and further suppressing an increase in viscosity of the monomer composition of the present invention to improve workability, 2 to 30 is preferable, and 4 to 20 is more preferable. In addition, the monomer composition of the present invention may contain the phosphate group-containing (meth) acrylate (A) alone or in combination of two or more. However, from the viewpoint of adhesion of the obtained copolymer, it is preferably contained alone.

[0014] <Dipyrrophosphate group-containing di(meth)acrylate (B)> The dipyrrophosphate group-containing di(meth)acrylate (B) used in the present invention is a compound represented by the following general formula (2).

[0015] [Chemical formula] (In the general formula (2), R 3 and R 4 are each a hydrogen atom or a methyl group, and R 5 and R 6is a linear or branched alkylene group having 1 to 6 carbon atoms, and m and l each represent the average number of moles added, and are 1 to 50.)

[0016] R in the general formula (2) 3 and R 4 are each a hydrogen atom or a methyl group, and can be appropriately selected in consideration of reactivity with other monomers to be copolymerized and the like. R in the general formula (2) 5 and R 6 are each a linear or branched alkylene group having 1 to 6 carbon atoms, and although not particularly limited, from the viewpoint of suppressing an increase in viscosity and generation of precipitates in the resulting copolymer solution, the number of carbon atoms is preferably 2 to 5, more preferably 3 to 4. R 5 and R 6 are preferably an ethylene group, a propylene group or a tetramethylene group from the viewpoint of availability. Among these, from the viewpoint of solubility of the resulting copolymer in an organic solvent, an ethylene group or a propylene group is more preferable, while from the viewpoint of flexibility of the resulting copolymer, a tetramethylene group is more preferable. m and l in the general formula (2) represent the average number of moles added, and may be 1 to 50, and are not particularly limited, but from the viewpoint of improving the solubility of the resulting copolymer in an organic solvent, suppressing an increase in viscosity and generation of precipitates in the resulting copolymer solution, and further suppressing an increase in viscosity of the monomer composition of the present invention to improve workability, 2 to 30 is preferable, and 4 to 20 is more preferable. In addition, the monomer composition of the present invention can contain the pyrophosphate group-containing di(meth)acrylate (B) alone or in combination of two or more, but from the viewpoint of adhesion of the resulting copolymer, it is preferably contained alone.

[0017] The phosphate group-containing (meth)acrylate (A) can be obtained by reacting phosphorus oxychloride with polyoxyalkylene (meth)acrylate. Further, after reacting phosphorus oxychloride with polyoxyalkylene (meth)acrylate, by adding water, unreacted P-Cl bonds can be converted to P-OH bonds by a hydrolysis reaction. The diphosphate group-containing di(meth)acrylate (B) can be produced by adjusting the amount of water added after reacting phosphorus oxychloride with polyoxyalkylene (meth)acrylate. Therefore, the phosphate group-containing (meth)acrylate (A) and the diphosphate group-containing di(meth)acrylate (B) can be synthesized together. At this time, the ratio of the diphosphate group-containing di(meth)acrylate (B) to the phosphate group-containing (meth)acrylate (A) can be adjusted by changing the amount of water added after reacting phosphorus oxychloride with polyoxyalkylene (meth)acrylate. The smaller the amount of water added, the larger the ratio of the diphosphate group-containing di(meth)acrylate (B). The raw material polyoxyalkylene (meth)acrylate can be used alone or in combination of two or more, but from the viewpoint of the adhesion of the obtained copolymer, it is preferably used alone.

[0018] <Other components> The monomer composition of the present invention may further contain other components such as a polymerization inhibitor within a range not impairing the object of the present invention.

[0019] The monomer composition of the present invention preferably contains a polymerization inhibitor from the viewpoint of improving storage stability. By containing a polymerization inhibitor, the reaction of the (meth)acryloyl group is suppressed during storage of the monomer composition of the present invention, so that gelation of the monomer composition of the present invention can be suppressed. As the polymerization inhibitor that the monomer composition of the present invention may contain, known ones can be used and are not particularly limited. For example, phenolic compounds, nitroso compounds, and phenothiazine compounds can be mentioned.

[0020] <Monomer Composition of the Present Invention> The monomer composition of the present invention contains the above-mentioned phosphate group-containing (meth)acrylate (A) and diphosphate group-containing di(meth)acrylate (B). With respect to 100% by mass of the monomer composition, the content of the phosphate group-containing (meth)acrylate (A) is 94 to 99.99% by mass, and the content of the diphosphate group-containing di(meth)acrylate (B) is 0.01 to 5% by mass. Since the content of the phosphate group-containing (meth)acrylate (A) in the monomer composition of the present invention is 94% by mass or more, it is suitably used as a monomer material for copolymerizing the phosphate group-containing (meth)acrylate (A). Further, since the content of the diphosphate group-containing di(meth)acrylate (B) in the monomer composition of the present invention is 0.01 to 5% by mass, in the solution polymerization of the monomer composition of the present invention and other monomers, crosslinking between phosphate groups can be suppressed. Therefore, an increase in viscosity and the generation of precipitates in the resulting copolymer solution can be suppressed. The copolymer obtained by copolymerizing the phosphate group-containing (meth)acrylate (A) using the monomer composition of the present invention has good solvent solubility due to sufficiently containing phosphate groups, and further has good solvent solubility also because the crosslinked structure in the copolymer is not too much. On the other hand, if the content of the diphosphate group-containing di(meth)acrylate (B) contained in the monomer composition is too high, the crosslinked structure formed by radical polymerization becomes too many, and as a result, the resulting copolymer has reduced flexibility. Consequently, the adhesion to metal may decrease, or the viscosity of the copolymer solution may increase.

[0021] The content of the phosphate group-containing (meth)acrylate (A) relative to 100% by mass of the monomer composition of the present invention may be 94 to 99.9% by mass. However, from the viewpoint of preferably using the monomer composition of the present invention as a monomer material for copolymerizing the phosphate group-containing (meth)acrylate (A), it is preferably 96% by mass or more, more preferably 98% by mass or more, still more preferably 99% by mass or more. On the other hand, from the point of sufficiently containing the pyrophosphate group-containing di(meth)acrylate (B) in the monomer composition of the present invention, it is preferably 99.9% by mass or less, more preferably 99.5% by mass or less.

[0022] The content of the pyrophosphate group-containing di(meth)acrylate (B) relative to 100% by mass of the monomer composition of the present invention may be 0.01 to 5% by mass. However, from the point of improving the effects of the present invention described above, the lower limit is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, still more preferably 0.5% by mass or more, and the upper limit is preferably 4.0% by mass or less, more preferably 2.0% by mass or less, still more preferably 1.0% by mass or less.

[0023] In the monomer composition of the present invention, the mass ratio of the phosphate group-containing (meth)acrylate (A) to the pyrophosphate group-containing di(meth)acrylate (B) is not particularly limited. However, with respect to 100 parts by mass of the total amount of the phosphate group-containing (meth)acrylate (A) and the pyrophosphate group-containing di(meth)acrylate (B), the content of the pyrophosphate group-containing di(meth)acrylate (B) is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, still more preferably 0.5 part by mass or more as the lower limit from the point of suppressing cross-linking between phosphate groups, and preferably 5 parts by mass or less, more preferably 4.0 parts by mass or less, still more preferably 2.0 parts by mass or less, even more preferably 1.0 part by mass or less as the upper limit from the point of suppressing a decrease in flexibility.

[0024] In 100% by mass of the monomer composition of the present invention, the total content of the phosphate group-containing (meth)acrylate (A) and the diphosphate group-containing di(meth)acrylate (B) is preferably 99% by mass or more, more preferably 99.5% by mass or more, still more preferably 99.9% by mass or more, and may be 100% by mass, from the viewpoint that the monomer composition of the present invention can be suitably used as a monomer material for copolymerizing the phosphate group-containing (meth)acrylate (A). The monomer composition of the present invention may contain other components other than the phosphate group-containing (meth)acrylate (A) and the diphosphate group-containing di(meth)acrylate (B) within a range that does not impair the object of the present disclosure. However, the content of the other components is preferably 1% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.1% by mass or less, based on 100% by mass of the monomer composition.

[0025] Typical examples of the other components other than the phosphate group-containing (meth)acrylate (A) and the diphosphate group-containing di(meth)acrylate (B) contained in the monomer composition of the present invention are polymerization inhibitors. In the monomer composition of the present invention, the content of the polymerization inhibitor is not particularly limited, but is preferably 0 to 0.5% by mass, more preferably 0.01 to 0.1% by mass, still more preferably 0.01 to 0.05% by mass, based on 100% by mass of the monomer composition. Also, the content of the polymerization inhibitor is preferably 0 to 0.5 parts by mass, more preferably 0.01 to 0.1 parts by mass, still more preferably 0.01 to 0.05 parts by mass, based on 100 parts by mass of the total amount of the phosphate group-containing (meth)acrylate (A) and the diphosphate group-containing di(meth)acrylate (B). When the monomer composition of the present invention contains a polymerization inhibitor, gelation during storage is suppressed and storage stability is improved. On the other hand, when the content of the polymerization inhibitor is below the above upper limit value, the monomer composition of the present invention is suppressed from coloring during storage.

[0026] <Method for Producing Monomer Composition of the Present Invention> The method for producing the monomer composition of the present invention is not particularly limited. For example, a polyoxyalkylene (meth)acrylate, which is a compound represented by the following formula (1’), and phosphorus oxychloride are reacted at a low temperature of 0 to 20 °C in an organic solvent, and then water is added to the resulting solution and further reacted at 40 to 60 °C. In this method, by adjusting the amount of water added, the timing of adding water, etc., an oil phase containing the phosphate group-containing (meth)acrylate (A) and the diphosphate group-containing di(meth)acrylate (B) in a mass ratio of 95:5 to 99.99:0.01 and an aqueous phase can be obtained. A polymerization inhibitor may be further added to the oil phase. By removing the aqueous phase and the organic solvent from the obtained mixture, the monomer composition of the present invention can be obtained. The amount of water added after the reaction of polyoxyalkylene (meth)acrylate and phosphorus oxychloride is not particularly limited, but is preferably 20 to 50 parts by mass with respect to 100 parts by mass of phosphorus oxychloride. Further, it is preferable to add water after polyoxyalkylene (meth)acrylate and phosphorus oxychloride have sufficiently reacted. In addition, the reaction of polyoxyalkylene (meth)acrylate and phosphorus oxychloride is preferably carried out in the presence of a base such as triethylamine in order to neutralize the acid generated by the reaction. When an additive such as a polymerization inhibitor is contained in the monomer composition of the present invention, in the above production method, the additive may be added at any timing. When adding a polymerization inhibitor, it is preferable to add the polymerization inhibitor after hydrolyzing the remaining phosphorus oxychloride after the reaction with polyoxyalkylene (meth)acrylate so that the polymerization inhibitor does not react during the production of the monomer composition of the present invention.

[0027]

Chemical formula

[0028] The explanations of the symbols in the general formula (1’) are the same as the explanations of the symbols in the general formula (1).

[0029] Incidentally, the monomer composition of the present invention can also be obtained by mixing a phosphate group-containing (meth)acrylate (A) and a diphosphate group-containing di(meth)acrylate (B).

[0030] <Use of the monomer composition> The use of the monomer composition of the present invention is not particularly limited, and examples thereof include a film-forming material. The film-forming material is not particularly limited, and examples thereof include adhesives and pressure-sensitive adhesives used in various fields such as dentistry, medicine, machinery, building materials, and electronic materials, as well as paints, inks, and coating agents. The monomer composition of the present invention may be added as a copolymerization component, for example, in the above-mentioned film-forming material or the like. Alternatively, a copolymer or a copolymer solution obtained by copolymerizing the monomer composition of the present invention with a monomer (C) described later may be used as a binder component or a dispersant of the above-mentioned film-forming material or the like.

[0031] <Polymerizable composition of the present invention> The polymerizable composition of the present invention contains at least the above-described monomer composition of the present invention and a monomer (C). Here, the monomer (C) is a monomer different from both the phosphate group-containing (meth)acrylate (A) and the diphosphate group-containing di(meth)acrylate (B), and corresponds to the above-mentioned "other monomer". Since the polymerizable composition of the present invention contains the phosphate group-containing (meth)acrylate (A) and the pyrophosphate group-containing di(meth)acrylate (B) in the above-described proportions in the monomer composition of the present invention described above, crosslinking between phosphate groups is suppressed when subjected to a polymerization reaction. Therefore, in the copolymer solution obtained by solution-polymerizing the polymerizable composition of the present invention, an increase in viscosity is suppressed and the generation of precipitates is suppressed. Further, the copolymer obtained using the polymerizable composition of the present invention can be imparted with desired acidity and hydrophilicity by adjusting the amount of phosphate groups to be introduced. Furthermore, since an increase in the crosslinked structure in the copolymer can be suppressed and a decrease in flexibility can be suppressed, a copolymer having improved adhesion to a metal can be obtained.

[0032] The monomer (C) contained in the polymerizable composition of the present invention may be any compound capable of copolymerizing with the phosphate group-containing (meth)acrylate (A) and the pyrophosphate group-containing di(meth)acrylate (B), and is appropriately selected according to the use and is not particularly limited. From the viewpoint of reactivity, a compound containing a radically polymerizable group is usually used as the monomer (C). Further, the monomer (C) may be a monofunctional monomer or a polyfunctional monomer. The monofunctional monomer is not particularly limited, and examples thereof include (meth)acrylate monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, polyethylene glycol di(meth)acrylate, 2-(meth)acryloyloxyethyltrimethylammonium chloride; (meth)acrylic acid; (meth)acrylamide monomers such as N-methylol(meth)acrylamide, N-methoxymethyl(meth)acrylamide, 4-(meth)acryloylmorpholine; styrene-based monomers such as styrene, α-methylstyrene, p-methoxystyrene, p-phenylstyrene, o-chlorostyrene, vinylnaphthalene, styrenesulfonic acid, styrenesulfonate; olefin-based monomers such as vinylcyclohexane, cyclohexene, 2-norbornene, ethylene, propylene, butene, etc. The polyfunctional monomer is not particularly limited, and examples thereof include (meth)acrylate-based polyfunctional monomers such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate; aromatic-based polyfunctional monomers such as divinylbenzene, 4,4'-divinylbiphenyl, 1,5-divinylnaphthalene, 2,2-bis((meth)acryloyloxyphenyl)propane, etc. Although not particularly limited, when the monomer (C) contains an alkyl (meth)acrylate having an alkyl group having 1 to 8 carbon atoms such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc., it is preferable from the viewpoint that the adhesion of the resulting copolymer tends to be good. Further, the polymerizable composition of the present invention containing the alkyl (meth)acrylate as the monomer (C) can be suitably used as an adhesive or a pressure-sensitive adhesive.

[0033] The content of the monomer composition of the present invention relative to 100% by mass of the total solid content contained in the polymerizable composition of the present invention is not particularly limited, but from the viewpoint of imparting sufficient acidity, hydrophilicity, and flexibility to the resulting copolymer, it is preferably 1% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more. From the same viewpoint, the content of the phosphate group-containing (meth)acrylate (A) relative to 100% by mass of all the monomers contained in the polymerizable composition of the present invention is preferably 1% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more. The upper limit of the content of the monomer composition of the present invention relative to 100% by mass of the total solid content contained in the polymerizable composition of the present invention is appropriately adjusted according to the use of the polymerizable composition and is not particularly limited. However, from the viewpoint of the adhesion of the resulting copolymer, it is preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably 40% by mass or less. From the same viewpoint, the content of the phosphate group-containing (meth)acrylate (A) relative to 100% by mass of all the monomers contained in the polymerizable composition of the present invention is preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably 40% by mass or less. In the present invention, the solid content means all substances other than the solvent, and liquid monomers and the like are included in the solid content.

[0034] In the polymerizable composition of the present invention, the total amount of the monomer components relative to 100% by mass of the total solid content may be appropriately adjusted according to the use and is not particularly limited. For example, it may be 50% by mass or more, 70% by mass or more, 90% by mass or more, or 99% by mass or more.

[0035] The polymerizable composition of the present invention may further contain other components such as additives and solvents, if necessary, within a range not impairing the object of the present disclosure. The additives that the polymerizable composition of the present invention may contain are not particularly limited. For example, polymerization inhibitors, polymerization initiators, molecular weight regulators, fillers, colorants, defoamers, dispersants, leveling agents, matting agents, ultraviolet absorbers, light stabilizers, antioxidants, heat resistance improvers, slip agents, preservatives, plasticizers, film-forming aids, and the like can be mentioned.

[0036] The polymerization inhibitor contained in the polymerizable composition of the present invention may be one contained in the monomer composition of the present invention, or may be added separately from the monomer composition of the present invention. Examples of the polymerization inhibitor that the polymerizable composition of the present invention may contain include the same ones as those that the monomer composition of the present invention described above may contain. In the polymerizable composition of the present invention, the content of the polymerization inhibitor is not particularly limited, but is preferably 0 to 0.5 parts by mass, more preferably 0.01 to 0.1 parts by mass, and still more preferably 0.01 to 0.05 parts by mass with respect to 100 parts by mass of the total amount of the monomer components contained in the polymerizable composition. By including a polymerization inhibitor, the polymerizable composition of the present invention suppresses gelation during storage and improves storage stability. On the other hand, in the polymerizable composition of the present invention, when the content of the polymerization inhibitor is below the above upper limit value, the polymerizable composition of the present invention suppresses coloring during storage.

[0037] The polymerization initiator is appropriately selected according to the use and is not particularly limited. For example, persulfates such as potassium persulfate, sodium persulfate, and ammonium persulfate; oil-soluble azo compounds such as azobisisobutyronitrile and 2,2'-azobis(2,4-dimethylvaleronitrile); water-soluble azo compounds such as 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide} and 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide}; organic peroxides such as benzoyl peroxide, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxyisobutyrate, and t-butyl peroxyneodecanoate, and the like can be mentioned. When the polymerizable composition of the present invention contains a polymerization initiator, the content of the polymerization initiator in the polymerizable composition is not particularly limited. However, from the viewpoint of sufficiently promoting the polymerization reaction, it is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the total amount of the monomer components contained in the polymerizable composition.

[0038] The polymerizable composition of the present invention may contain a solvent for dissolving or dispersing the monomer component, additives, etc., if necessary. The solvent is appropriately selected from various organic solvents and water according to the application, and is not particularly limited. However, from the viewpoint of general-purpose solubility, an organic solvent is preferably used. When the polymerizable composition of the present invention contains a solvent, the solid content concentration of the polymerizable composition of the present invention is appropriately adjusted according to the application and is not particularly limited. For example, it may be 10 to 90% by mass.

[0039] The method for producing the polymerizable composition of the present invention is not particularly limited. For example, the polymerizable composition of the present invention can be obtained by mixing the monomer composition of the present invention, the monomer (C), and other components such as additives or solvents that are added as necessary, by a known method.

[0040] The use of the polymerizable composition of the present invention is not particularly limited. For example, the above-mentioned film-forming materials and the like for which the monomer composition of the present invention can be used can be mentioned. For example, the polymerizable composition of the present invention that does not contain a solvent may be used as an adhesive or a pressure-sensitive adhesive, etc., and the polymerizable composition of the present invention that contains a solvent may be used as a paint, an ink, or a coating agent, etc. Further, the copolymer or the copolymer solution obtained by subjecting the polymerizable composition of the present invention to a polymerization reaction may be used as a binder component such as the above-mentioned film-forming material or a dispersant.

[0041] <The copolymer of the present invention> The copolymer of the present invention may be a copolymer of the phosphate group-containing (meth)acrylate (A) and the pyrophosphate group-containing di(meth)acrylate (B) contained in the monomer composition of the present invention described above and a monomer (C) different from these, and is not particularly limited. Note that the description of the monomer (C) used in the copolymer of the present invention is the same as the description of the monomer (C) used in the polymerizable composition of the present invention described above. In the copolymer of the present invention, in the structural unit derived from the phosphate group-containing (meth)acrylate (A), cross-linking between phosphate groups is suppressed, so that it has a desired acidity and hydrophilicity, and a decrease in flexibility is suppressed. Therefore, the adhesion to a metal is improved. Further, when the copolymer of the present invention is dissolved or dispersed in a solution, the viscosity increase and the generation of precipitates of the solution are suppressed because the cross-linking between phosphate groups in the copolymer is suppressed.

[0042] In the copolymer of the present invention, the content of the structural unit derived from the phosphate group-containing (meth)acrylate (A) with respect to 100% by mass of all the structural units is preferably 1% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more, from the viewpoints of having sufficient acidity and hydrophilicity and flexibility. The upper limit of the content of the structural unit derived from the phosphate group-containing (meth)acrylate (A) is appropriately adjusted according to the use of the copolymer of the present invention and is not particularly limited, but from the viewpoint of adhesion, it is preferably 60% by mass or less, more preferably 50% by mass or less, still more preferably 40% by mass or less.

[0043] In the copolymer of the present invention, the mass ratio of the structural unit derived from the phosphoric acid group-containing (meth)acrylate (A) to the structural unit derived from the pyrophosphoric acid group-containing di(meth)acrylate (B) is not particularly limited. However, with respect to 100 parts by mass of the total amount of these structural units, the content of the structural unit derived from the pyrophosphoric acid group-containing di(meth)acrylate (B) is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, still more preferably 0.5 part by mass or more from the viewpoint of suppressing crosslinking between phosphoric acid groups, and preferably 5.0 parts by mass or less, more preferably 4.0 parts by mass or less, still more preferably 2.0 parts by mass or less, even more preferably 1.0 part by mass or less from the viewpoint of suppressing a decrease in flexibility.

[0044] The copolymer of the present invention may be, for example, a copolymer obtained by subjecting the polymerizable composition of the present invention described above to a polymerization reaction. As the polymerization method for obtaining the copolymer of the present invention, for example, known polymerization methods such as solution polymerization, bulk polymerization, precipitation polymerization, suspension polymerization, and emulsion polymerization can be appropriately selected and employed, and there is no particular limitation. However, by adopting solution polymerization, the effects of the monomer composition of the present invention described above are likely to be exhibited.

[0045] The use of the copolymer of the present invention is not particularly limited. For example, in the film-forming material and the like described above, it can be used as, for example, a binder component or a dispersant.

[0046] <The copolymer solution of the present invention> The copolymer solution of the present invention contains at least the copolymer of the present invention described above and a solvent. The solvent contained in the copolymer solution of the present invention is appropriately selected from various organic solvents and water according to the use, and is not particularly limited. However, from the viewpoint of general solubility, an organic solvent is preferably used. In addition, the copolymer solution of the present invention may further contain other components different from the copolymer or the solvent of the present invention, as long as the object of the present invention is not impaired. Examples of the other components include the same additives as those that the above-described polymerizable composition of the present invention may contain.

[0047] In the copolymer solution of the present invention, the content of the copolymer of the present invention may be appropriately adjusted according to the use and is not particularly limited. With respect to 100% by mass of the total solid content of the copolymer solution of the present invention, the content of the copolymer of the present invention may be, for example, 50% by mass or more, 70% by mass or more, 90% by mass or more, or 99% by mass or more. In addition, the solid content concentration of the copolymer solution of the present invention may be appropriately adjusted according to the use and is not particularly limited, but may be, for example, 10 to 90% by mass.

[0048] By using the above-described monomer composition of the present invention, the viscosity of the copolymer solution of the present invention at 25°C can be, for example, 5 mPa·S or less, and may be less than 3 mPa·S in some cases.

[0049] In addition, by using the above-described monomer composition of the present invention, the turbidity of the copolymer solution of the present invention can be, for example, less than 10 ppm, and may be less than 5 ppm in some cases.

[0050] The copolymer solution of the present invention is preferably obtained by solution polymerization using the above-described monomer composition of the present invention as a copolymerization component, from the viewpoint that the effects of the above-described monomer composition of the present invention are easily exhibited. The copolymer solution of the present invention may be a copolymer solution obtained by solution polymerizing the above-described polymerizable composition of the present invention. The use of the copolymer solution of the present invention is not particularly limited. For example, the copolymer solution of the present invention can be used as it is as the above-described film-forming material, etc., or the copolymer solution of the present invention can also be used as a binder component or a dispersant, etc. in the above-described film-forming material, etc.

Example

[0051] Hereinafter, embodiments of the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited only to these Examples. Note that parts and % are based on mass unless otherwise specified.

[0052] In Examples and Comparative Examples, the structures of polyoxyalkylene (meth)acrylates (A'-1) to (A'-6) used as raw materials, as well as the structures of the obtained phosphate group-containing (meth)acrylates (A-1) to (A-6) and pyrophosphate group-containing di(meth)acrylates (B-1) to (B-6) are shown in Table 1 below. Polyoxyalkylene (meth)acrylates (A'-1) to (A'-6) are compounds in which R 1 , R 2 and n are as shown in Table 1, and phosphate group-containing (meth)acrylates (A-1) to (A-6) are compounds in which R 1 , R 2 and n are as shown in Table 1, and pyrophosphate group-containing di(meth)acrylates (B-1) to (B-6) are compounds in which R 3 , R 4 , R 5 , R 6 , m and l are as shown in Table 1.

[0053]

Table 1

[0054] [Example 1] (1) Preparation of monomer composition Into a 1 L four-necked flask equipped with a dropping funnel, a stirring blade, and a thermometer, 60 g of phosphorus oxychloride and 218 g of methylcyclohexane were placed, and these were cooled to 10 °C. Then, a mixed solution of 132 g of polyoxyalkylene (meth)acrylate (A'-1) and 37.8 g of triethylamine was added dropwise into the flask over 1 hour, and then stirred at 15 °C for 3 hours. Then, the obtained mixed solution was heated to 45 °C, 35.4 g of ion-exchanged water was added, and after stirring at 45 °C for 2 hours, 60 g of ion-exchanged water was further added and stirred at 45 °C for 1 hour to obtain a solution. The obtained solution was transferred to a 1 L separatory funnel, allowed to stand at 50 °C for 30 minutes to separate layers, and then the aqueous layer was drained to obtain an organic layer. 120 g of ion water was added to the obtained organic layer, stirred at 50 °C for 10 minutes, then transferred to a 1 L separatory funnel, allowed to stand at 50 °C for 30 minutes to separate layers, and then the aqueous layer was drained to obtain an organic layer. The solution obtained by repeating the same operation 2 more times was returned to a 1 L flask, 0.16 g of 4-methylphenol was added, and then methylcyclohexane and water in the system were distilled off at 60 °C, 50 torr, and for 3 h to obtain the monomer composition of Example 1. The monomer composition of Example 1 contained a phosphate group-containing (meth)acrylate (A-1), a pyrophosphate group-containing di(meth)acrylate (B-1), and 4-methylphenol as a polymerization inhibitor.

[0055] (2) Preparation of polymerizable composition 15 g of the monomer composition obtained above, 35 g of methyl methacrylate (MMA), and 150 g of toluene were mixed to prepare the polymerizable composition of Example 1.

[0056] (3) Preparation of copolymer solution 1 g of Perbutyl (registered trademark) ND-100 (manufactured by NOF Corporation, t-butyl peroxyneodecanoate) was added to the polymerizable composition obtained above, and reacted at 75 °C for 5 hours to prepare the copolymer solution of Example 1. The obtained copolymer solution contained 50 g of a copolymer of a phosphate group-containing (meth)acrylate (A-1), a pyrophosphate group-containing di(meth)acrylate (B-1), and additionally added MMA contained in the monomer composition, and 150 g of toluene. The obtained copolymer had a content of structural units derived from the phosphate group-containing (meth)acrylate (A-1) of 29.97% by mass.

[0057] [Example 2] A monomer composition, a polymerizable composition, and a copolymer solution of Example 2 were obtained by the same procedure as in Example 1, except that the amount of ion-exchanged water added first was changed from 35.4 g to 29.6 g. The monomer composition of Example 2 contained a phosphate group-containing (meth)acrylate (A-1), a pyrophosphate group-containing di(meth)acrylate (B-1), and 4-methylphenol as a polymerization inhibitor. Also, the obtained copolymer solution of Example 2 contained 50 g of a copolymer of a phosphate group-containing (meth)acrylate (A-1), a pyrophosphate group-containing di(meth)acrylate (B-1), and additionally added MMA contained in the monomer composition, and 150 g of toluene. The obtained copolymer of Example 2 had a content of structural units derived from the phosphate group-containing (meth)acrylate (A-1) of 29.85% by mass.

[0058] [Example 3] A monomer composition, a polymerizable composition, and a copolymer solution of Example 3 were obtained by the same procedure as in Example 1, except that the amount of ion-exchanged water added first was changed from 35.4 g to 24.5 g. The monomer composition of Example 3 contained a phosphate group-containing (meth)acrylate (A-1), a pyrophosphate group-containing di(meth)acrylate (B-1), and 4-methylphenol as a polymerization inhibitor. In addition, the copolymer solution obtained in Example 3 contained 50 g of a copolymer of a phosphate group-containing (meth)acrylate (A-1), a pyrophosphate group-containing di(meth)acrylate (B-1), and further added MMA, and 150 g of toluene. The copolymer obtained in Example 3 had a content of structural units derived from the phosphate group-containing (meth)acrylate (A-1) of 29.1% by mass.

[0059] [Example 4] The monomer composition, polymerizable composition, and copolymer solution of Example 4 were obtained by the same procedure as in Example 1, except that the amount of ion-exchanged water added first was changed from 35.4 g to 20.5 g. The monomer composition of Example 4 contained a phosphate group-containing (meth)acrylate (A-1), a pyrophosphate group-containing di(meth)acrylate (B-1), and 4-methylphenol as a polymerization inhibitor. In addition, the copolymer solution obtained in Example 4 contained 50 g of a copolymer of a phosphate group-containing (meth)acrylate (A-1), a pyrophosphate group-containing di(meth)acrylate (B-1), and further added MMA, and 150 g of toluene. The copolymer obtained in Example 4 had a content of structural units derived from the phosphate group-containing (meth)acrylate (A-1) of 29.85% by mass.

[0060] [Example 5] The monomer composition, polymerizable composition, and copolymer solution of Example 5 were obtained by the same procedure as in Example 1, except that 238 g of polyoxyalkylene (meth)acrylate (A'-2) was used instead of 132 g of polyoxyalkylene (meth)acrylate (A'-1), and the addition amount of 4-methylphenol was changed from 0.16 g to 0.262 g. The monomer composition of Example 5 contained a phosphate group-containing (meth)acrylate (A-2), a pyrophosphate group-containing di(meth)acrylate (B-2), and 4-methylphenol as a polymerization inhibitor. In addition, the copolymer solution obtained in Example 5 contained 50 g of a copolymer of a phosphate group-containing (meth)acrylate (A-2), a pyrophosphate group-containing di(meth)acrylate (B-2), and further added MMA, which were contained in the monomer composition, and 150 g of toluene. The copolymer obtained in Example 5 had a content of structural units derived from the phosphate group-containing (meth)acrylate (A-2) of 29.85% by mass.

[0061] [Example 6] A monomer composition, a polymerizable composition, and a copolymer solution of Example 6 were obtained in the same procedure as in Example 1, except that 450 g of polyoxyalkylene (meth)acrylate (A'-3) was used instead of 132 g of polyoxyalkylene (meth)acrylate (A'-1), and the addition amount of 4-methylphenol was changed from 0.16 g to 0.474 g. The monomer composition of Example 6 contained a phosphate group-containing (meth)acrylate (A-3), a pyrophosphate group-containing di(meth)acrylate (B-3), and 4-methylphenol as a polymerization inhibitor. In addition, the copolymer solution obtained in Example 6 contained 50 g of a copolymer of a phosphate group-containing (meth)acrylate (A-3), a pyrophosphate group-containing di(meth)acrylate (B-3), and further added MMA, which were contained in the monomer composition, and 150 g of toluene. The copolymer obtained in Example 6 had a content of structural units derived from the phosphate group-containing (meth)acrylate (A-3) of 29.85% by mass.

[0062] [Example 7] A monomer composition, a polymerizable composition, and a copolymer solution of Example 7 were obtained in the same procedure as in Example 1, except that 106 g of polyoxyalkylene (meth)acrylate (A'-4) was used instead of 132 g of polyoxyalkylene (meth)acrylate (A'-1), and the addition amount of 4-methylphenol was changed from 0.16 g to 0.13 g. The monomer composition of Example 7 contained a phosphate group-containing (meth)acrylate (A-4), a pyrophosphate group-containing di(meth)acrylate (B-4), and 4-methylphenol as a polymerization inhibitor. Further, the copolymer solution obtained in Example 7 contained 50 g of a copolymer of the phosphate group-containing (meth)acrylate (A-4) and the pyrophosphate group-containing di(meth)acrylate (B-4) contained in the monomer composition, and further added MMA, and 150 g of toluene. The copolymer obtained in Example 7 had a content of structural units derived from the phosphate group-containing (meth)acrylate (A-4) of 29.85% by mass.

[0063] [Example 8] The monomer composition, polymerizable composition, and copolymer solution of Example 8 were obtained by the same procedure as in Example 1, except that 158 g of polyoxyalkylene (meth)acrylate (A'-5) was used instead of 132 g of polyoxyalkylene (meth)acrylate (A'-1), and the addition amount of 4-methylphenol was changed from 0.16 g to 0.182 g. The monomer composition of Example 8 contained a phosphate group-containing (meth)acrylate (A-5), a pyrophosphate group-containing di(meth)acrylate (B-5), and 4-methylphenol as a polymerization inhibitor. Further, the copolymer solution obtained in Example 8 contained 50 g of a copolymer of the phosphate group-containing (meth)acrylate (A-5) and the pyrophosphate group-containing di(meth)acrylate (B-5) contained in the monomer composition, and further added MMA, and 150 g of toluene. The copolymer obtained in Example 8 had a content of structural units derived from the phosphate group-containing (meth)acrylate (A-5) of 29.85% by mass.

[0064] [Example 9] Instead of 132 g of polyoxyalkylene (meth)acrylate (A'-1), 128 g of polyoxyalkylene (meth)acrylate (A'-6) was used, and the amount of 4-methylphenol added was changed from 0.16 g to 0.152 g. Otherwise, the monomer composition, polymerizable composition, and copolymer solution of Example 9 were obtained by the same procedure as in Example 1. The monomer composition of Example 9 contained a phosphate group-containing (meth)acrylate (A-6), a pyrophosphate group-containing di(meth)acrylate (B-6), and 4-methylphenol as a polymerization inhibitor. In addition, the copolymer solution obtained in Example 9 contained 50 g of a copolymer of the phosphate group-containing (meth)acrylate (A-6) and the pyrophosphate group-containing di(meth)acrylate (B-6) contained in the monomer composition, and further added MMA, and 150 g of toluene. The copolymer obtained in Example 9 had a content of structural units derived from the phosphate group-containing (meth)acrylate (A-6) of 29.85% by mass.

[0065] [Comparative Example 1] In Example 1, the procedure of adding 35.4 g of ion-exchanged water and stirring at 45°C for 2 hours, and then adding 60 g of ion-exchanged water and stirring at 45°C for 1 hour to obtain a solution was changed to the procedure of adding 90 g of ion-exchanged water and stirring at 45°C for 3 hours to obtain a solution. Otherwise, the monomer composition, polymerizable composition, and copolymer solution of Comparative Example 1 were obtained by the same procedure as in Example 1. The monomer composition of Comparative Example 1 contained a phosphate group-containing (meth)acrylate (A-1) and 4-methylphenol as a polymerization inhibitor, and did not contain a pyrophosphate group-containing di(meth)acrylate. In addition, the copolymer solution obtained in Comparative Example 1 contained 50 g of a copolymer of the phosphate group-containing (meth)acrylate (A-1) contained in the monomer composition and further added MMA, and 150 g of toluene. The copolymer obtained in Comparative Example 1 had a content of structural units derived from the phosphate group-containing (meth)acrylate (A-1) of 30% by mass.

[0066] [Comparative Example 2] In Example 1, the addition amount of 4-methylphenol was changed from 0.16 g to 1.6 g. Further, 35.4 g of ion-exchanged water was added, and after stirring at 45°C for 2 hours, 60 g of ion-exchanged water was further added, and the procedure of stirring at 45°C for 1 hour to obtain a solution was changed to the procedure of adding 90 g of ion-exchanged water and stirring at 45°C for 3 hours to obtain a solution. A monomer composition, a polymerizable composition, and a copolymer solution of Comparative Example 2 were obtained in the same procedure as in Example 1 except for this change. The monomer composition of Comparative Example 2 contained a phosphate group-containing (meth)acrylate (A-1) and 4-methylphenol as a polymerization inhibitor, and did not contain a pyrophosphate group-containing di(meth)acrylate. Further, the copolymer solution obtained in Comparative Example 2 contained 50 g of a copolymer of a phosphate group-containing (meth)acrylate (A-1) contained in the monomer composition and further added MMA, and 150 g of toluene. The copolymer obtained in Comparative Example 2 had a content of structural units derived from the phosphate group-containing (meth)acrylate (A-1) of 30% by mass.

[0067] <lc-ms> From the total ion chromatogram (TIC) of the monomer composition measured by liquid chromatography-mass spectrometry (LC-MS), the extracted ion chromatogram (EIC) of the phosphate group-containing (meth)acrylate (A) and the extracted ion chromatogram (EIC) of the pyrophosphate group-containing di(meth)acrylate (B) extracted from the TIC, the content of the phosphate group-containing (meth)acrylate (A) and the content of the pyrophosphate group-containing di(meth)acrylate (B) contained in the monomer composition were calculated according to the following calculation formula. In the following calculation formula, (A) represents "phosphate group-containing (meth)acrylate (A)", and (B) represents "pyrophosphate group-containing di(meth)acrylate (B)".

[0068]

Number

[0069] The LC-MS was performed under the following conditions. (LC-MS Measurement Conditions) Measuring instrument: 6430 Triple Quad LC / MS (manufactured by Agilent Technologies) Measurement sample: Methanol solution of monomer composition 200 μg / mL Column: Cadenza CD-C18 (manufactured by IMTAKT, length: 100 mm, inner diameter: φ3 mm, packing agent particle size 3 μm) Column temperature: 40 °C Mobile phase: 5 mM CH 3 COONH 4 Methanol solution / 10 mM CH 3 COONH 4 Aqueous solution was pumped for 5 minutes at a volume ratio of 50 / 50, then changed to a composition of volume ratio 70 / 30 in 2 minutes while pumping, pumped for 6 minutes at a volume ratio of 70 / 30, then changed to a composition of volume ratio 90 / 10 in 2 minutes while pumping, pumped for 5 minutes at a volume ratio of 90 / 10, and then changed to a composition of 100 / 0 in 2 minutes while pumping. Injection volume: 1 μL Analysis mode: Mass range m / z = 100 - 1000 Ionization mode: ESI+ Fragmenter voltage: 120 V

[0070] Table 2 shows the content of phosphate group-containing (meth)acrylate (A), the content of pyrophosphate group-containing di(meth)acrylate (B), and the content of 4-methylphenol when the total amount of the monomer composition is 100% by mass. The content of 4-methylphenol was calculated from the charged amount.

[0071] <Evaluation> 1. High-temperature storage stability of monomer composition After allowing 30 g of the monomer composition to stand at 50 °C for 240 hours, a measurement sample was obtained by filtering with quantitative filter paper No. 5A (manufactured by ADVANTEC). For the said measurement sample, using a Gardner colorimeter (equipment name: COMPARATOR ILLUMINATOR, manufactured by Daylite), in accordance with JIS K 0071-2:1998, the Gardner color number at 25 °C was measured. Based on the following criteria, the high-temperature storage stability of the monomer composition was evaluated from the measured Gardner color number. The larger the Gardner color number, the more the monomer composition was colored by high-temperature storage. Table 2 shows the measurement results of the Gardner color number in parentheses together with the evaluation results of the high-temperature storage stability of the monomer composition. (Criteria) ◎: Gardner color number is 1 or more and 2 or less 〇: Gardner color number is 3 or more and 5 or less ×: Gardner color number is 6 or more

[0072] 2. Viscosity of copolymer solution Using a digital viscometer (manufactured by BROOKFIELD, model: DV-I Prime), at a temperature of 25 °C and with a spindle LV-1, the viscosity (mPa·S) of the copolymer solution was measured. Based on the following criteria, the effect of suppressing the increase in the viscosity of the copolymer solution was evaluated from the measured viscosity. The lower the viscosity of the copolymer solution, the more the increase in viscosity was suppressed. Table 2 shows the measurement results of the viscosity in parentheses together with the evaluation results. (Criteria) ◎: Viscosity less than 3 mPa·S 〇: Viscosity between 3 mPa·S and 5 mPa·S (inclusive) ×: Viscosity exceeding 5 mPa·S

[0073] 3. Turbidity of the copolymer solution Using an integrating sphere turbidimeter (manufactured by Mitsubishi Chemical Corporation, SEP-PT-706D), the turbidity (ppm) of the copolymer solution was measured. Based on the measured viscosity and the following criteria, the effect of suppressing the generation of precipitates accompanying the copolymerization reaction was evaluated. The lower the turbidity of the copolymer solution, the more the generation of precipitates was suppressed. Table 2 shows the measurement results of turbidity in parentheses together with the evaluation results. (Criteria) ◎: Turbidity less than 5 ppm ○: Turbidity between 5 ppm and 10 ppm (excluding 10 ppm) △: Turbidity between 10 ppm and 30 ppm (excluding 30 ppm) ×: Turbidity 30 ppm or more

[0074] 4. Adhesion of the copolymer Using a coating rod (Mayer bar) No. 32 manufactured by RDS, the copolymer solution was coated on an aluminum plate and dried at 80 °C for 30 minutes to prepare a test piece having a copolymer coating film (thickness 20 μm) on the aluminum plate. For the said test piece, according to JIS K5600-5-6, a cross-cut test was carried out by creating a grid of 25 squares at 2 mm intervals, and the number of squares in which the coating film did not peel off among the 25 squares was measured. The fewer the number of squares in which the coating film did not peel off, the better the adhesion of the copolymer coating film to the aluminum plate. Based on the following criteria, the adhesion between the copolymer and the metal was evaluated. Table 2 shows the number of squares in which the coating film did not peel off among the 25 squares in parentheses together with the evaluation results. (Criteria) ◎: The number of squares in which the coating film did not peel off is 23 or more out of 25 squares 〇: The number of squares in which the coating film did not peel off is between 20 and 22 (inclusive) out of 25 squares ×: The number of squares in which the coating film did not peel off is 19 or less out of 25 squares

[0075]

Table 2

[0076] As shown in Table 2, the monomer compositions obtained in Examples 1 to 9 contained the phosphate group-containing (meth)acrylate (A) represented by the general formula (1) and the diphosphate group-containing di(meth)acrylate (B) represented by the general formula (2). With respect to 100% by mass of the monomer composition, the content of the phosphate group-containing (meth)acrylate (A) was 94 to 99.99% by mass, and the content of the diphosphate group-containing di(meth)acrylate (B) was 0.01 to 5% by mass, which was the monomer composition according to the present invention. The copolymer solution obtained by solution polymerization of the monomer compositions obtained in Examples 1 to 9 and MMA had an increased viscosity suppressed, and also had a low turbidity because the generation of precipitates was suppressed. Further, the coating film of the copolymer obtained by copolymerizing the monomer compositions obtained in Examples 1 to 9 and MMA had excellent adhesion to an aluminum plate. The excellent adhesion of the coating film was because the coating film had hydrophilicity, acidity, and flexibility. Therefore, it is presumed that the coating film has excellent adhesion to metals such as iron, aluminum, and copper. Among them, in Examples 2, 5, 8, and 9, the content of the diphosphate group-containing di(meth)acrylate (B) contained in the monomer composition was 0.2% by mass or more and 2.0% by mass or less, and in the phosphate group-containing (meth)acrylate (A) and the diphosphate group-containing di(meth)acrylate (B), R in the general formula (1) 2 structure and R in the general formula (2) 5 and R 6 structure were linear or branched alkylene groups having 3 to 4 carbon atoms, and n in the general formula (1) and m and l in the general formula (2) were 4 to 20, whereby the effect of suppressing the increase in viscosity in the copolymer solution was particularly excellent.

[0077] Since the monomer compositions obtained in Comparative Examples 1 and 2 did not contain the diphosphate group-containing di(meth)acrylate (B) represented by the general formula (2), the copolymer solution obtained by solution polymerization of the monomer composition and MMA had a high viscosity, and the turbidity was high due to the generation of precipitates. In addition, the coating films of the copolymers obtained by copolymerizing the monomer compositions obtained in Comparative Examples 1 to 2 and MMA had low flexibility and were brittle, so they were likely to crack or peel off and had poor adhesion to the aluminum plate. In Comparative Example 2, although the content of the polymerization inhibitor was increased, the effect of suppressing the increase in the viscosity of the copolymer solution and the generation of precipitates was insufficient, and the adhesion between the coating film of the copolymer and the aluminum plate was also insufficient. Moreover, the monomer composition of Comparative Example 2 was likely to be colored by storage at high temperature.

Claims

【Claim 1】 A monomer composition comprising a phosphate group-containing (meth)acrylate (A) represented by the following general formula (1) and a pyrophosphate group-containing di(meth)acrylate (B) represented by the following general formula (2), The monomer composition is characterized in that, based on 100% by mass of the monomer composition, the content of the phosphate group-containing (meth)acrylate (A) is 94 to 99.99% by mass, and the content of the pyrophosphate group-containing di(meth)acrylate (B) is 0.01 to 5% by mass. 【Chemical Formula 1】 (In general formula (1), R １ is a hydrogen atom or a methyl group, and R ２ is a linear or branched alkylene group having 1 to 6 carbon atoms, and n represents the average number of moles added and is 1 to 50.) [Chemical Formula 2] (In the general formula (2), R ３ and R ４ are each a hydrogen atom or a methyl group, and R ５ and R ６ are each a linear or branched alkylene group having 1 to 6 carbon atoms, m and l each represent the average number of added moles, and are 1 to 50.)