JP7803057B2 - Polymer compound and method for producing the same, composition and method for producing the same, and resin composition - Google Patents

Description

The present invention relates to a polymer compound and a method for producing the same, a composition and a method for producing the same, and a resin composition.

Polymer compounds having multiple polymer chains bonded to thiol groups within the molecule are used in paints, adhesives, pressure-sensitive adhesives, compatibilizers, dispersants, etc. In recent years, environmental considerations have led to a demand for reducing the amount of volatile organic compounds (VOCs) used when used in the above-mentioned applications. Since VOCs are used as solvents for applying resins, reducing the solution viscosity from the standpoint of handleability would enable a reduction in VOCs.
As a method for reducing the solution viscosity of a polymer compound, a method of introducing branches into the polymer compound is known.

Patent Document 1 discloses a polymer compound obtained by radically polymerizing a vinyl monomer using an organic sulfide compound, which is formed by the Michael addition of a polyvalent mercaptan and a vinyl compound, as a chain transfer agent.

Patent Document 2 discloses a polymer compound obtained by reacting a polyfunctional thiol compound with a compound having a reactive group that reacts with a thiol group in a specified ratio range to obtain a chain transfer agent having a thiol group, and then radically polymerizing a vinyl compound in the presence of the chain transfer agent.

Japanese Patent Application Laid-Open No. 2001-064252 International Publication No. 2020/203837

It is generally known that there is a correlation between the molecular weight of a polymer compound and its solution viscosity. The higher the molecular weight, the higher the solution viscosity. In some cases, achieving the minimum molecular weight necessary to satisfy the required physical properties does not result in sufficient viscosity reduction.
Patent Documents 1 and 2 disclose methods for lowering the viscosity by introducing branches into a polymer compound, but the resulting product is a mixture of a linear polymer and a branched polymer, and there is room for improvement in terms of lowering the viscosity by increasing the content of the branched polymer and the degree of branching.

The present invention aims to provide a polymer compound having a high content of branched polymer and a high degree of branching of the branched polymer, and a method for producing the same.

[1] A polymer compound in which a plurality of polymer chains are linked by a divalent or higher linking group,
the divalent or higher valent linking group has either or both of a thiol group and a thioether structure,
the ratio of absolute weight average molecular weight (absolute _Mw ) to relative weight average molecular weight (relative _Mw ) (absolute _Mw /relative _Mw ) is 1.25 or more;
when the divalent or higher valent linking group has a thiol group, the thiol group of the divalent or higher valent linking group has an acid dissociation constant pKa value with water of 8.0 or less;
when the divalent or higher valent linking group has a thioether structure, and when the divalent or higher valent linking group has two or more thioether structures, the shortest distance between sulfur atoms in the thioether structures is 300 or more in terms of molecular weight;
High molecular compound.
[2] The polymer compound according to [1], wherein the divalent or higher valent linking group includes a structure represented by formula (1):
In formula (1), ^R1 and ^R2 each independently represent one selected from the group consisting of a hydrogen atom, a monovalent hydrocarbon group, a hydroxyl group, and a monovalent electron-withdrawing group; ^R3 represents one selected from the group consisting of an oxygen atom, a divalent hydrocarbon group, and a divalent electron-withdrawing group; and -* represents a bond.
[3] The polymer compound according to [1] or [2], wherein when the divalent or higher valent linking group has a thiol group, the divalent or higher valent linking group has 1 to 300 thiol groups per molecule of the polymer compound.
[4] The polymer compound according to any one of [1] to [3], wherein the absolute M _w /relative M _w is 3.00 or less.
[5] A step of reacting a polyfunctional thiol compound (A) with a compound (B) having a reactive group that reacts with a thiol group to obtain a chain transfer agent (F) having a thiol group;
and a step of polymerizing a vinyl compound in the presence of the chain transfer agent (F) having a thiol group and a radical polymerization initiator to obtain a polymer compound.
[6] The method for producing a polymer compound according to [5], wherein the acid dissociation constant pKa of the thiol group contained in the polyfunctional thiol compound (A) with respect to water is 8.0 or less.
[7] The method for producing a polymer compound according to [5] or [6], wherein the compound (B) having a reactive group that reacts with a thiol group has a molecular weight of 300 or more.
[8] The method for producing a polymer compound according to any one of [5] to [7], wherein the reactive group that reacts with a thiol group is at least one selected from the group consisting of an acrylate group and a glycidyl group.
[9] A composition containing, as a main component, a compound (E) having a moiety derived from a polyfunctional thiol compound (A) and a moiety derived from a compound (B) having a reactive group that reacts with a thiol group,
A composition satisfying formula (11) and formula (12).
r×(f _A −1)×(f _B −1)<1.2 (11)
r=(f _B ×y)/(f _A ×x) (12)
In formula (11) and formula (12), _fA is the average number of thiol groups per molecule of the polyfunctional thiol compound (A), and _fB is the average number of reactive groups per molecule of the compound (B). _fA is 2.0 or more, and _fB is 1.2 or more, except for the case where only the compound (A) has two thiol groups and only the compound (B) has two reactive groups.
In formula (12), x and y are x and y, respectively, when the molar ratio of the moiety derived from the polyfunctional thiol compound (A) to the moiety derived from the compound (B) is x:y.
[10] The composition according to [9], wherein the compound (E) is a compound having at least one thiol group per molecule.
[11] The composition according to [9] or [10], wherein f _A +f _B > 4.0.
[12] The composition according to any one of [9] to [11], wherein the reactive group that reacts with a thiol group is at least one selected from the group consisting of acrylate groups, and has a formula weight of 300 or more.
[13] The composition according to any one of [9] to [12], which is a chain transfer agent in a radical polymerization reaction system.
[14] A method for producing a composition, comprising reacting a polyfunctional thiol compound (A) with a compound (B) having a reactive group that reacts with a thiol group under conditions that satisfy formulas (13) and (14).
r'×(f _A -1)×(f _B -1)<1.2 (13)
r'=(f _B ×y')/(f _A ×x')...(14)
In formula (13) and formula (14), _fA is the average number of thiol groups per molecule of the polyfunctional thiol compound (A), and _fB is the average number of reactive groups per molecule of the compound (B). _fA is 2.0 or more, and _fB is 1.2 or more, except for the case where only the compound (A) has two thiol groups and only the compound (B) has two reactive groups.
In the formula (14), x' and y' respectively represent x' and y' when the molar ratio of the polyfunctional thiol compound (A) to the compound (B) is x':y'.
[15] The method for producing the composition according to [13], wherein f _A +f _B >4.0.
[16] The method for producing the composition according to [14] or [15], comprising reacting the polyfunctional thiol compound (A) with a compound (B) having a reactive group that reacts with the thiol group in the presence of a catalyst (C).
[17] The amount of the solvent at the start of the reaction between the polyfunctional thiol compound (A) and the compound (B) having a reactive group reactive with a thiol group is 50 mass% or less of the total mass of the polyfunctional thiol compound (A) and the compound (B) having a reactive group reactive with a thiol group,
The method for producing a composition according to any one of [14] to [16], wherein the external temperature during the reaction of the polyfunctional thiol compound (A) with the compound (B) having a reactive group that reacts with a thiol group is 10 to 50°C.
[18] A resin composition comprising the polymer compound according to any one of [1] to [4] or the composition according to any one of [9] to [13], and a thermoplastic resin.

The present invention provides a polymer compound having a high content of branched polymer and a high degree of branching of the branched polymer, as well as a method for producing the same.

The following describes in detail the embodiments for implementing the present invention, but the present invention is not limited to the embodiments described below, and various modifications are possible without departing from the spirit of the present invention.

In this specification and claims, a numerical range expressed as "to" means a numerical range that includes the numerical values before and after "to" as the lower and upper limits.
In this specification and claims, "(meth)acrylic" means acrylic and methacrylic. Similarly, "(meth)acrylate" means acrylate and methacrylate, and "(meth)acryloyloxy" means acryloyloxy and methacryloyloxy.

[Polymer Compound and Method for Producing the Same]
The polymer compound of the present invention is a polymer compound in which a plurality of polymer chains are linked together via a linking group that is divalent or more.

The lower limit of the ratio of the absolute weight average molecular weight (absolute weight average molecular weight; hereinafter, also simply referred to as "relative _Mw ") to the relative weight average molecular weight (relative weight average molecular weight; hereinafter, also simply referred to as "relative _Mw ") of the polymer compound of the present invention (absolute _Mw /relative _Mw ) is 1.25, preferably 1.27, and more preferably 1.29. When the ratio (absolute _Mw /relative _Mw ) is equal to or greater than the lower limit, it is possible to prevent a solution containing the polymer compound of the present invention from becoming highly viscous.
The upper limit of the ratio (absolute _Mw /relative _Mw ) is usually 3.00, preferably 2.10, more preferably 2.00, even more preferably 1.95, and still more preferably 1.90. When the ratio (absolute _Mw /relative _Mw ) is equal to or less than the lower limit, the resin composition to which the polymer compound of the present invention is added has excellent heat resistance.
The range of the ratio (absolute M _w /relative M _w ) is preferably from 1.25 to 3.00, more preferably from 1.25 to 2.10, even more preferably from 1.25 to 2.0, even more preferably from 1.27 to 1.95, and even more preferably from 1.29 to 1.90.

The lower limit of the relative _Mw of the polymer compound of the present invention is preferably 1,000, more preferably 1,500, further preferably 5,000, even more preferably 10,000, still more preferably 20,000, and particularly preferably 40,000.
The upper limit of the relative _Mw of the polymer compound of the present invention is preferably 2,000,000, more preferably 1,800,000, even more preferably 1,500,000, still more preferably 1,200,000, even more preferably 800,000, and particularly preferably 500,000.
The relative _Mw range of the polymer compound of the present invention is preferably 1,000 to 2,000,000, more preferably 1,500 to 1,800,000, even more preferably 5,000 to 1,500,000, still more preferably 10,000 to 1,200,000, even more preferably 20,000 to 800,000, and particularly preferably 40,000 to 500,000.

The relative Mw of the polymer compound of the present invention is a value calculated as polymethyl methacrylate as measured by gel permeation chromatography (GPC). The relative _Mw of the polymer compound of the present invention is a molecular weight calculated by the method described in the Examples below.

The lower limit of the absolute _Mw of the polymer compound of the present invention is preferably 1,250, more preferably 1,500, further preferably 5,000, even more preferably 10,000, still more preferably 20,000, and particularly preferably 40,000.
The upper limit of the absolute _Mw of the polymer compound of the present invention is preferably 2,000,000, more preferably 1,800,000, even more preferably 1,500,000, still more preferably 1,200,000, even more preferably 800,000, and particularly preferably 500,000.
The absolute _Mw range of the polymer compound of the present invention is preferably 1,250 to 2,000,000, more preferably 1,500 to 1,800,000, even more preferably 5,000 to 1,500,000, still more preferably 10,000 to 1,200,000, even more preferably 20,000 to 800,000, and particularly preferably 40,000 to 500,000.

The absolute Mw of the polymer compound is a molecular weight measured using gel permeation chromatography (GPC) and a light scattering detector. The relative _Mw of the polymer compound of the present invention is specifically a molecular weight calculated by the method described in the Examples below.

The solution viscosity of the polymer compound of the present invention is a viscosity obtained by dissolving the polymer compound of the present invention in butyl acetate to prepare a solution having a solid content (polymer compound) concentration of 40 mass %, and measuring the viscosity of the prepared polymer compound solution at room temperature (25°C) using an E-type viscometer.
The solution viscosity thus determined depends on the molecular weight of the polymer compound, but is preferably 5.0 Pa·s or less, more preferably 2.0 Pa·s or less.

The divalent or higher valent linking group has either or both of a thiol group (-SH) and a thioether structure (-S-).
The divalent or higher valent linking group may have both a thiol group and a thioether structure, or may have only one of them.

When the divalent or higher valent linking group has a thiol group, the number of thiol groups per one divalent or higher valent linking group may be one or two or more.
When the divalent or higher valent linking group has a thioether structure, the number of thioether structures per one divalent or higher valent linking group may be one or two or more.

In the present invention, a "divalent or higher valent linking group" refers to a moiety that links multiple polymer chains within a polymer compound. The multiple polymer chains may be the same or different. The polymer chains are typically composed of repeating units described below. Furthermore, the polymer chains may be homopolymers or copolymers.

When the divalent or higher valent linking group has a thiol group, the upper limit of the acid dissociation constant pKa of the thiol group of the divalent or higher valent linking group with water is 8.0, and more preferably 7.5.
In this case, the lower limit of the acid dissociation constant pKa of the thiol group of the divalent or higher linking group with respect to water is preferably 6.5, more preferably 7.0.
Furthermore, in this case, the acid dissociation constant pKa of the thiol group of the divalent or higher linking group with respect to water is preferably in the range of 6.5 to 8.0, more preferably 7.0 to 7.5.

The acid dissociation constant (pKa) of the thiol group of the divalent or higher linking group with respect to water can be calculated using Advanced Chemistry Development (ACD/Labs) Software.

When the divalent or higher valent linking group has a thiol group, the divalent or higher valent linking group preferably has 1 to 300 thiol groups, and more preferably 5 to 100 thiol groups, per molecule of the polymer compound.

In the case where the divalent or higher valent linking group has a thioether structure, and the divalent or higher valent linking group has two or more thioether structures, the lower limit of the shortest distance between sulfur atoms of the thioether structures, calculated in terms of molecular weight, is 300, preferably 400, and more preferably 500.
In this case, the upper limit of the shortest distance between sulfur atoms in the thioether structure, calculated in terms of molecular weight, is 1,000, and more preferably 900.
Furthermore, in this case, the range of the value of the shortest distance between sulfur atoms in the thioether structure converted into molecular weight is preferably 300 to 1,000, more preferably 400 to 900.

When the molecular weight of the reactive compound (B) is known, the molecular weight equivalent of the smallest distance between sulfur atoms in the thioether structure can be calculated using that value. If the molecular weight is not known, the molecular weight can be determined from the molecular weight peak derived from the linking group, which is detected by, for example, decomposing the ester bond of the linking group with alcohol and performing mass spectrometry such as LC/MS measurement.

The divalent or higher linking group is preferably a divalent or higher group derived from the chain transfer agent (F) described below.

The chain transfer agent (F) has a moiety derived from the polyfunctional thiol compound (A) and a moiety derived from a compound (B) (hereinafter, sometimes simply referred to as “compound (B)”) having a reactive group that reacts with a thiol group.
The chain transfer agent (F) is a compound having a thioether structure formed by reaction of a thiol group of the polyfunctional thiol compound (A) with a reactive group reactive with the thiol group of the compound (B), and having a plurality of thiol groups. The chain transfer agent (F) may also be a mixture of a plurality of different compounds.

The polymer compound of the present invention can be obtained, for example, by reacting a polyfunctional thiol compound (A) with a compound (B) to synthesize a chain transfer agent (F) having multiple thiol groups, and polymerizing a vinyl compound in the presence of the chain transfer agent (F) and a radical polymerization initiator.
That is, the polymer compound of the present invention can be produced by radically polymerizing a vinyl compound using a chain transfer agent (F), with some of the multiple thiol groups of the chain transfer agent (F) serving as starting points for polymer chain growth, thereby bonding the thiol groups to the polymer chain, and leaving the remaining thiol groups unreacted.

The polyfunctional thiol compound (A) is a compound having at least two thiol groups in the molecule.
The polyfunctional thiol compound (A) may be an aliphatic polythiol compound or an aromatic polythiol compound.

The fatty acid polythiol compound may be an aliphatic polythiol compound that does not have sulfur atoms other than the thiol group, or an aliphatic polythiol compound that has sulfur atoms other than the thiol group.

Examples of aliphatic polythiol compounds that do not contain sulfur atoms other than the thiol groups include methanedithiol, 1,2-ethanedithiol, 1,1-propanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 2,2-propanedithiol, 1,6-hexanedithiol, 1,2,3-propanetrithiol, 1,1-cyclohexanedithiol, 1,2-cyclohexanedithiol, 2,2-dimethylpropane-1,3-dithiol, 3,4-dimethoxybutane-1,2-dithiol, 2-methylcyclohexane-2,3-dithiol, and 1,1-bis(2-methylcyclohexane-2,3-dithiol). (mercaptomethyl)cyclohexane, thiomalic acid bis(2-mercaptoethyl ester), 2,3-dimercapto-1-propanol(2-mercaptoacetate), 2,3-dimercapto-1-propanol(3-mercaptopropionate), 2,3-dimercapto-1-propanol(3-mercaptobutyrate), diethylene glycol bis(2-mercaptoacetate), diethylene glycol bis(3-mercaptopropionate), diethylene glycol bis(3-mercaptobutyrate), 1,2-dimercaptopropyl methyl ether, 2,3 -dimercaptopropyl methyl ether, 2,2-bis(mercaptomethyl)-1,3-propanedithiol, bis(2-mercaptoethyl) ether, ethylene glycol bis(2-mercaptoacetate), ethylene glycol bis(3-mercaptopropionate), ethylene glycol bis(3-mercaptobutyrate), tetraethylene glycol bis(3-mercaptopropionate), trimethylolpropane bis(2-mercaptoacetate), trimethylolpropane bis(3-mercaptopropionate), trimethylolpropane bis(3-mercaptopropyl methyl ether), Examples include pentaerythritol tetrakis(2-mercaptobutyrate), pentaerythritol tetrakis(2-mercaptoacetate) (also known as pentaerythritol tetrakisthioglycolate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), tetrakis(mercaptomethyl)methane, dipentaerythritol hexakis(2-mercaptoacetate), dipentaerythritol hexakis(3-mercaptopropionate), and dipentaerythritol hexakis(3-mercaptobutyrate).

Aliphatic polythiol compounds having sulfur atoms in addition to the thiol groups include bis(mercaptomethyl) sulfide, bis(mercaptomethyl) disulfide, bis(mercaptoethyl) sulfide, bis(mercaptoethyl) disulfide, bis(mercaptopropyl) sulfide, bis(mercaptomethylthio)methane, bis(2-mercaptoethylthio)methane, bis(3-mercaptopropylthio)methane, 1,2-bis(mercaptomethylthio)ethane, 1,2-bis(2 -mercaptoethylthio)ethane, 1,2-bis(3-mercaptopropyl)ethane, 1,3-bis(mercaptomethylthio)propane, 1,3-bis(2-mercaptoethylthio)propane, 1,3-bis(3-mercaptopropylthio)propane, 1,2,3-tris(mercaptomethylthio)propane, 1,2,3-tris(2-mercaptoethylthio)propane, 1,2,3-tris(3-mercaptopropylthio)propane, 1,2-bis[(2-mercaptoethyl)thio] -3-mercaptopropane, 4-mercaptomethyl-3,6-dithia-1,8-octanedithiol, 4,8-dimercaptomethyl-1,11-mercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-mercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-mercapto-3,6,9-trithiaundecane, tetrakis(mercaptomethylthiomethyl)methane, tetrakis(2-mercaptoethylthiomethyl)meth Examples include tetrakis(3-mercaptopropylthiomethyl)methane, bis(2,3-dimercaptopropyl)sulfide, bis(1,3-dimercaptopropyl)sulfide, 2,5-dimercapto-1,4-dithiane, 2,5-dimercaptomethyl-1,4-dithiane, 2,5-dimercaptomethyl-2,5-dimethyl-1,4-dithiane, bis(mercaptomethyl)disulfide, bis(mercaptoethyl)disulfide, and bis(mercaptopropyl)disulfide.

Furthermore, examples of aliphatic polythiol compounds having sulfur atoms in addition to the thiol group include hydroxymethyl sulfide bis(2-mercaptoacetate), hydroxymethyl sulfide bis(3-mercaptopropionate), hydroxymethyl sulfide bis(3-mercaptobutyrate), hydroxyethyl sulfide bis(2-mercaptoacetate), hydroxyethyl sulfide bis(3-mercaptopropionate), hydroxyethyl sulfide bis(3-mercaptobutyrate), hydroxypropyl sulfide bis(2-mercaptoacetate), hydroxypropyl sulfide bis(3-mercaptopropionate), hydroxypropyl sulfide bis(3-mercaptobutyrate), hydroxymethyl disulfide bis(2-mercaptoacetate), hydroxymethyl disulfide bis(3-mercaptopropionate), hydroxymethyl disulfide bis(3-mercaptobutyrate), hydroxyethyl disulfide bis(2-mercaptoacetate), hydroxyethyl disulfide bis(3-mercaptopropionate), hydroxyethyl disulfide bis(3-mercaptobutyrate), hydroxypropyl disulfide bis(2-mercaptoacetate), hydroxypropyl disulfide bis(3-mercaptopropionate), hydroxypropyl disulfide bis(3-mercaptobutyrate), 2-mercaptoethyl Ether bis(2-mercaptoacetate), 2-mercaptoethyl ether bis(3-mercaptopropionate), 2-mercaptoethyl ether bis(3-mercaptobutyrate), 1,4-dithiane-2,5-diol bis(2-mercaptoacetate), 1,4-dithiane-2,5-diol bis(3-mercaptopropionate), 1,4-dithiane-2,5-diol bis(3-mercaptobutyrate), thiodiglycolic acid bis(2-mercaptoethyl ester), thiodipropionic acid bis(2-mercaptoethyl ester), thiodibutanoic acid bis(2-mercaptoethyl ester), 4,4-thiodibutyric acid bis(2-mercaptoethyl ester), dithiodiglycolic acid bis(2-mercaptoethyl ester), Other examples include cholic acid bis(2-mercaptoethyl ester), dithiodipropionic acid bis(2-mercaptoethyl ester), dithiodibutanoic acid bis(2-mercaptoethyl ester), 4,4-dithiodibutyric acid bis(2-mercaptoethyl ester), thiodiglycolic acid bis(2,3-dimercaptopropyl ester), thiodipropionic acid bis(2,3-dimercaptopropyl ester), thiodibutanoic acid bis(2,3-dimercaptopropyl ester), dithioglycolic acid bis(2,3-dimercaptopropyl ester), dithiodipropionic acid bis(2,3-dimercaptopropyl ester), and dithiodibutanoic acid bis(2,3-dimercaptopropyl ester).

The aromatic polythiol compound may be an aromatic polythiol compound that does not contain sulfur atoms other than thiol groups, or an aromatic polythiol compound that contains sulfur atoms other than thiol groups.

Examples of aromatic polythiol compounds that do not have sulfur atoms other than the thiol group include 1,2-dimercaptobenzene, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,2-bis(mercaptomethyl)benzene, 1,3-bis(mercaptomethyl)benzene, 1,4-bis(mercaptomethyl)benzene, 1,2-bis(mercaptoethyl)benzene, 1,3-bis(mercaptoethyl)benzene, 1,4-bis(mercaptoethyl)benzene, 1,2,3-trimercaptobenzene, 1,2,4-trimercaptobenzene, 1,3,5-trimercaptobenzene, and 1,2,3-trimercaptobenzene. Examples include 1,2,4-tris(mercaptomethyl)benzene, 1,3,5-tris(mercaptomethyl)benzene, 1,2,3-tris(mercaptoethyl)benzene, 1,2,4-tris(mercaptoethyl)benzene, 1,3,5-tris(mercaptoethyl)benzene, 2,5-toluenedithiol, 3,4-toluenedithiol, 1,3-di(p-methoxyphenyl)propane-2,2-dithiol, 1,3-diphenylpropane-2,2-dithiol, phenylmethane-1,1-dithiol, and 2,4-di(p-mercaptophenyl)pentane.

Examples of aromatic polythiol compounds having sulfur atoms in addition to the thiol groups include 1,2-bis(mercaptoethylthio)benzene, 1,3-bis(mercaptoethylthio)benzene, 1,4-bis(mercaptoethylthio)benzene, 1,2,3-tris(mercaptomethylthio)benzene, 1,2,4-tris(mercaptomethylthio)benzene, 1,3,5-tris(mercaptomethylthio)benzene, 1,2,3-tris(mercaptoethylthio)benzene, 1,2,4-tris(mercaptoethylthio)benzene, and 1,3,5-tris(mercaptoethylthio)benzene.

The polyfunctional thiol compound (A) is preferably a fatty acid polythiol compound, and from the viewpoint of suppressing decomposition of the linking group due to chain transfer, an aliphatic polythiol compound without a disulfide bond is more preferred, and an aliphatic polythiol compound without sulfur atoms other than those in the thiol group is even more preferred.

The lower limit of the acid dissociation constant pKa of the thiol group contained in the polyfunctional thiol compound (A) with respect to water is preferably 5.0, more preferably 6.0.
When the acid dissociation constant pKa of the thiol group contained in the polyfunctional thiol compound (A) with respect to water is 6.0 or more, low molecular weight components that lead to deterioration in the physical properties of the resulting polymer compound are less likely to be produced.
The upper limit of the acid dissociation constant pKa of the thiol group contained in the polyfunctional thiol compound (A) with respect to water is preferably 8.5, more preferably 8.0.
When the acid dissociation constant pKa of the thiol group contained in the polyfunctional thiol compound (A) with respect to water is 8.0 or less, the degree of branching of the resulting polymer compound is improved, and a decrease in the solution viscosity can be expected while maintaining the molecular weight of the polymer compound.
The acid dissociation constant pKa of the thiol group contained in the polyfunctional thiol compound (A) with respect to water is preferably in the range of 5.0 to 8.5, more preferably 6.0 to 8.0.

The average number of thiol groups per molecule of the polyfunctional thiol compound (A) is preferably more than 1.5, more preferably 2 or more, and even more preferably 2.5 or more.
The average number of thiol groups per molecule of the polyfunctional thiol compound (A) is preferably 8 or less, more preferably 6 or less, and even more preferably 5 or less.
The average number of thiol groups per molecule of the polyfunctional thiol compound (A) is preferably more than 1.5 and not more than 8, more preferably 2 to 6, and even more preferably 2.5 to 5.

The polyfunctional thiol compound (A) is preferably a polyfunctional thiol compound having an ester bond in the molecule.
The polyfunctional thiol compound having an ester bond in the molecule is preferably a fatty acid polythiol compound having an ester bond in the molecule, more preferably an aliphatic polythiol compound having an ester bond in the molecule but not a disulfide bond, still more preferably an aliphatic polythiol compound having an ester bond in the molecule but not having a sulfur atom other than the thiol group, and even more preferably an aliphatic polythiol compound having an ester bond in the molecule and in which the thiol group is located at the β-position of the ester bond.

Examples of the polyfunctional thiol compound (A) include pentaerythritol tetrakis(3-mercaptopropionate (PEMP), pentaerythritol tetrakis(2-mercaptoacetate) (PEMA), dipentaerythritol hexakis(3-mercaptopropionate) (DPMP), tetraethylene glycol bis(3-mercaptopropionate) (EGMP), and pentaerythritol tetrakis(3-mercaptobutyrate).
The polyfunctional thiol compound (A) may be used alone or in combination of two or more kinds.

The lower limit of the molecular weight of the polyfunctional thiol compound (A) is preferably 80, more preferably 300.
When the molecular weight of the polyfunctional thiol compound (A) is equal to or greater than the lower limit, difficulty in handling due to odor is more easily alleviated.
The upper limit of the molecular weight of the polyfunctional thiol compound (A) is preferably 2,000, more preferably 800.
When the molecular weight of the polyfunctional thiol compound (A) is equal to or less than the upper limit, handling difficulties due to increased viscosity are more likely to be resolved.
The molecular weight of the polyfunctional thiol compound (A) is preferably in the range of 80 to 2,000, more preferably 300 to 800.
The molecular weight of the polyfunctional thiol compound (A) is a molecular weight theoretically calculated based on the chemical structure.

Compound (B) is a compound having at least one reactive group (hereinafter simply referred to as "reactive group") that reacts with a thiol group within the molecule.

The reactive group is, for example, a functional group that can react with a thiol group to form an S—C bond.
Examples of the reactive group include a (meth)acrylate group, a glycidyl group, and a vinyl group (excluding the vinyl group contained in the (meth)acrylate group).
The reactive group is preferably at least one selected from the group consisting of a (meth)acrylate group and a glycidyl group, more preferably a (meth)acrylate group, and even more preferably an acrylate group, because of its high addition reactivity with a thiol group.

The thiol group of the polyfunctional thiol compound (A) reacts with the (meth)acrylate group, glycidyl group, or vinyl group of the compound (B) to form a thioether structure (R-S-R'), where R and R' each represent any organic group.
This allows the polyfunctional thiol compound (A) to bond via the compound (B), allowing many thiol groups to be present at a distance within one molecule. By using this as a chain transfer agent (F), the resulting polymer chain is less susceptible to steric hindrance, making it possible to produce a polymer compound having multiple polymer chains. In other words, it becomes possible to produce a polymer compound having a high degree of branching, which is difficult to produce using the polyfunctional thiol compound (A) alone.

Examples of compound (B) include (meth)acrylic acid, mono(meth)acrylate compounds, poly(meth)acrylate compounds, monovinyl compounds, polyvinyl compounds, monoepoxy compounds, and polyepoxy compounds.

Examples of the mono(meth)acrylate compound include alkyl(meth)acrylates having a linear or branched alkyl group with 1 to 30 carbon atoms, hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, glycidyl(meth)acrylate, methoxyethyl(meth)acrylate, ethoxyethyl(meth)acrylate, and ethoxyethoxyethyl(meth)acrylate.

Examples of the poly(meth)acrylate compound include a diester compound obtained by reacting a diol with (meth)acrylic acid, a polyester compound obtained by reacting a compound having three or more hydroxyl groups per molecule with (meth)acrylic acid, and a compound obtained by reacting a compound having two or more epoxy groups with (meth)acrylic acid.

Diester compounds obtained by reacting the diol with acrylic acid include ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, Examples include glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 2-hydroxy-1,3-di(meth)acryloyloxypropane, 2,2-bis[4-((meth)acryloxyethoxy)phenyl]propane, 2,2-bis[4-((meth)acryloyloxy-polyethoxy)phenyl]propane, bis[4-((meth)acryloyloxy-ethoxy)phenyl]methane, and 2-hydroxy-1-(meth)acryloyloxy-3-(meth)acryloyloxypropane.

Examples of polyester compounds obtained by reacting the compound having three or more hydroxyl groups per molecule with (meth)acrylic acid include trimethylolpropane tri(meth)acrylate, tetramethylol tri(meth)acrylate, pentaerythritol tetrakis(meth)acrylate (tetramethylolmethane tetra(meth)acrylate), and dipentaerythritol hexakis(meth)acrylate.

Examples of compounds obtained by reacting the compound having two or more epoxy groups with (meth)acrylic acid include bisphenol A diglycidyl ether (meth)acrylic acid adduct and bisphenol F diglycidyl ether (meth)acrylic acid adduct.

Examples of the monovinyl compound include styrene compounds, vinyl ether compounds, fumaric acid, monoalkyl esters of fumaric acid, dialkyl esters of fumaric acid, maleic acid, monoalkyl esters of maleic acid, dialkyl esters of maleic acid, itaconic acid, monoalkyl esters of itaconic acid, dialkyl esters of itaconic acid, acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, vinyl acetate, vinyl ketone, vinylpyridine, and vinylcarbazole.
Examples of the styrene-based compound include α-methylstyrene, vinyltoluene, and styrene.
Examples of the vinyl ether compounds include methyl vinyl ether, ethyl vinyl ether, and isobutyl vinyl ether.

Examples of the polyvinyl compounds include butadiene, isoprene, and allyl acrylate, as well as compounds having a plurality of structures equivalent to the above-mentioned monovinyl compounds in one molecule.
An example of a compound having a plurality of structures equivalent to the monovinyl compound in one molecule is divinylbenzene.

Examples of the monoepoxy compounds include phenyl glycidyl ether, cresyl glycidyl ether, p-t-butylphenyl glycidyl ether, butyl glycidyl ether, alcohol glycidyl ethers having 12 to 14 carbon atoms, butane diglycidyl ether, hexane diglycidyl ether, cyclohexane dimethyl diglycidyl ether, and glycidyl ethers based on polyethylene glycol or polypropylene glycol.

Examples of the polyepoxy compound include neopentyl glycol diglycidyl ether, bisphenol-type epoxy resins, novolac-type epoxy resins, and compounds having a plurality of glycidyl groups.
Examples of the bisphenol type epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol A/bisphenol F copolymer type epoxy resin.
Examples of the novolac type epoxy resin include cresol novolac type epoxy resin and phenol novolac type epoxy resin.
Examples of the compound having a plurality of glycidyl groups include triglycidyl aminophenol, biphenyl diglycidyl ether, triglycidyl isocyanurate, polyglycidyl (meth)acrylate, and copolymers of glycidyl (meth)acrylate and vinyl monomers copolymerizable therewith.

The compound (B) is preferably at least one selected from the group consisting of 1,6-hexanediol diacrylate, ethylhexyl acrylate, trimethylolpropane triacrylate, and tetraethylene glycol diacrylate.
The compound (B) may be used alone or in combination of two or more kinds.

The lower limit of the number of the reactive groups per molecule of the compound (B) is preferably 1. When only one type of compound (B) is used, the lower limit of the number of reactive groups per molecule of the compound (B) is preferably 2.
The upper limit of the number of the reactive groups per molecule of the compound (B) is preferably 8, more preferably 6.
The number of reactive groups per molecule of compound (B) is preferably in the range of 1 to 8, more preferably 1 to 6. When only one compound (B) is used, the number of reactive groups per molecule of compound (B) is preferably in the range of 2 to 8, more preferably 2 to 6.

The lower limit of the average number of reactive groups per molecule of the compound (B) is preferably 1.2, more preferably 1.3, and even more preferably 1.5.
The upper limit of the average number of reactive groups per molecule of the compound (B) is preferably 8, more preferably 6, and even more preferably 3.
The average number of reactive groups per molecule of compound (B) is preferably in the range of 1.2 to 8, more preferably 1.3 to 6, and even more preferably 1.5 to 3, from the viewpoint of ease of obtaining the polymer compound of the present invention.

The lower limit of the molecular weight of the compound (B) is preferably 300, more preferably 600.
When the molecular weight of the compound (B) is equal to or greater than the lower limit, the degree of branching of the polymer produced when the compound (B) is used as a chain transfer agent (F) in polymerization is improved.
On the other hand, the upper limit of the molecular weight of the compound (B) is preferably 2,000, more preferably 1,000.
When the molecular weight of the compound (B) is equal to or less than the upper limit, handling difficulties due to increased viscosity can be more easily overcome.
The molecular weight of the compound (B) is preferably in the range of 300 to 2,000, more preferably 300 to 1,000, and even more preferably 600 to 1,000.
The molecular weight of the compound (B) is a molecular weight theoretically calculated based on the chemical structure.

The divalent or higher valent linking group preferably has a thioether structure.
When the divalent or higher valent linking group has a thioether structure, it preferably has a structure represented by formula (1) from the viewpoint of improving heat resistance.
The structure represented by formula (1) can be formed, for example, by reacting a thiol group of a polyfunctional thiol compound (A) with a (meth)acrylate group of a mono(meth)acrylate compound or a poly(meth)acrylate compound.

In formula (1), R ¹ and R ² each independently represent a hydrogen atom, a monovalent hydrocarbon group, a hydroxyl group, or a monovalent electron-withdrawing group.

The monovalent hydrocarbon group is not particularly limited, but is preferably an alkyl group, more preferably an alkyl group having 6 or fewer carbon atoms, even more preferably a methyl group or ethyl group, and even more preferably a methyl group.

The monovalent electron-withdrawing group is not particularly limited, but is preferably a halogen atom such as a fluorine atom or a chlorine atom, a halogenated hydrocarbon group such as a trifluoromethyl group, a carboxyl group (-COOH), an alkoxycarbonyl group (-COOR) such as a methoxycarbonyl group, an aryloxycarbonyl group (-COOR) such as a phenoxycarbonyl group, an acyl group (-COR) such as an acetyl group, a cyano group (-CN), an aryl group or a substituted aryl group, a nitro group (-NO ₂ ), a sulfo group (-SO ₃ H), an alkoxysulfonyl group (-SO ₃ R), an alkanesulfonyl group (-SO ₂ R), an alkanesulfinyl group (-SOR), a carbamoyl group (-CONH ₂ ), or an alkylcarbamoyl group (-CONHR).

^R1 is preferably a hydrogen atom, and ^R2 is preferably a hydrogen atom, a methyl group, or a hydroxyl group.

In formula (1), ^R3 is an oxygen atom, a divalent hydrocarbon group, or a divalent electron-withdrawing group.

The divalent hydrocarbon group is not particularly limited, but is preferably an alkylene group, more preferably an alkylene group having 6 or fewer carbon atoms, even more preferably a methylene group or ethylene group, and even more preferably a methylene group.

The divalent electron-withdrawing group is not particularly limited, but is preferably a carbonyl group (-CO-), an ester group (-COO-), a sulfo group (-SO ₃ -), a sulfonyl group (-SO ₂ -), a sulfinyl group (-SO-), an amide group (-CONH-), an aryl group, or a substituted aryl group.

^R3 is preferably a methylene group or an ester group.

In formula (1), -* represents a bond.

In formula (1), a combination in which ^R1 is a hydrogen atom, ^R2 is a hydrogen atom, a methyl group, or a hydroxyl group, and ^R3 is a methylene group or an ester group is preferred, and a combination in which ^R1 is a hydrogen atom, ^R2 is a hydroxyl group, and ^R3 is a methylene group, or a combination in which ^R1 is a hydrogen atom, ^R2 is a hydrogen atom or a methyl group, and R3 is an ester group is more preferred.

In formula (2), X is an oxygen atom or a sulfur atom, preferably an oxygen atom.

In formula (2), -* represents a bond.

The divalent or higher valent linking group preferably has a thioether structure, and more preferably has a structure represented by formula (1), because it has excellent long-term thermal stability and is easy to produce, making it easy to obtain a variety of compounds. When the divalent or higher valent linking group has a thioether structure, the polymer compound of the present invention tends to have excellent long-term thermal stability because the thioether structure has the ability to decompose peroxides in the system.

The chain transfer agent (F) can be obtained, for example, by subjecting a polyfunctional thiol compound (A) and a compound (B) to an addition polymerization reaction.
In the addition polymerization reaction of multifunctional thiol compound (A) and compound (B), solvent may be used or no solvent may be used.When using a solvent in the addition polymerization reaction, the solvent is not particularly limited, and for example, methyl ethyl ketone, tetrahydrofuran (THF) or toluene can be used.However, when using a solvent in the addition polymerization reaction, in order to improve reaction efficiency, the amount of solvent at the start of the addition reaction is preferably 50 mass% or less, more preferably 30 mass% or less, even more preferably 10 mass% or less, based on the total mass of multifunctional thiol compound (A) and compound (B), and it is even more preferable to not use a solvent.

The molar ratio (reactive groups/thiol groups) of the total amount of thiol groups in the polyfunctional thiol compound (A) used in the addition polymerization reaction of the polyfunctional thiol compound (A) and the compound (B) to the total amount of reactive groups in the compound (B) is not particularly limited in its lower limit, but is preferably 1/8 or more.
On the other hand, the upper limit of the molar ratio (reactive group/thiol group) is not particularly limited, but is preferably 1/1.2 or less, more preferably 1/1.5 or less, and even more preferably 1/3 or less.
When the molar ratio (reactive group/thiol group) is equal to or greater than the lower limit and equal to or less than the upper limit, a chain transfer agent (F) having a plurality of thiol groups is easily obtained.

The external temperature during the addition polymerization reaction between the polyfunctional thiol compound (A) and the compound (B) is not particularly limited, but is preferably 10 to 80°C, more preferably 10 to 50°C, and even more preferably 25 to 50°C. The external temperature during the reaction refers, for example, to the set temperature of the water bath or oil bath used to heat the reaction vessel.

The reaction time for the addition polymerization reaction between the polyfunctional thiol compound (A) and the compound (B) is preferably 0.05 to 10 hours, more preferably 2 to 5 hours. A reaction time of 0.05 hours or longer makes it easier to prevent the reaction raw materials from remaining unreacted.

The addition polymerization reaction between polyfunctional thiol compound (A) and compound (B) is preferably carried out in the presence of catalyst (C). There are no particular restrictions on the catalyst (C), but a phosphine compound is preferred. The phosphine compound undergoes nucleophilic attack on the reactive group of compound (B), yielding a phosphine enolate, a zwitterionic intermediate. Because the phosphine enolate is highly basic, it abstracts a proton from the thiol group, forming a phosphonium and simultaneously generating a thiolate anion. The thiolate anion then undergoes nucleophilic addition to the reactive group, abstracting a proton from another thiol group or phosphonium, thereby bonding the thiol group and reactive group.

Examples of the phosphine compound include phosphines and diphosphines.
Examples of the phosphines include trimethylphosphine, triethylphosphine, tripropylphosphine, triisopropylphosphine, tri-n-butylphosphine, tri-t-butylphosphine, tri-n-octylphosphine, tricyclohexylphosphine, tribenzylphosphine, triphenylphosphine, diphenylmethylphosphine, dimethylphenylphosphine, diphenylcyclohexylphosphine, dicyclohexylphenylphosphine, diethylphenylphosphine, tri-o-tolylphosphine, and tri- Examples include m-tolylphosphine, tri-p-tolylphosphine, tri-2,4-xylylphosphine, tri-2,5-xylylphosphine, tri-3,5-xylylphosphine, tris(p-methoxyphenyl)phosphine, tris(p-t-butoxyphenyl)phosphine, di-t-butylphenylphosphine, [4-(N,N-dimethylamino)phenyl]di-t-butylphosphine, di-t-butyl(2-butenyl)phosphine, di-t-butyl(3-methyl-2-butenyl)phosphine, and trimethylphosphine.

Examples of the diphosphines include 1,2-bis(dimethylphosphino)ethane, bis(diphenylphosphino)methane, 1,2-bis(diphenylphosphino)ethane, 1,2-bis(diphenylphosphino)propane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 2,3-bis(diphenylphosphino)butane, and 1,5-bis(diphenylphosphino)pentane.

The catalyst (C) may be used alone or in combination of two or more.
The amount of catalyst (C) used is preferably 0.001 to 10% by mass, more preferably 0.002 to 5% by mass, and even more preferably 0.004 to 3% by mass, relative to 1 g of polyfunctional thiol compound (A). When the amount of catalyst (C) used is at least the lower limit of the above range, the reaction proceeds easily, and when it is at most the upper limit of the above range, there is no effect of the remaining catalyst.

The polymer chain in the polymer compound of the present invention has a structural unit derived from the radical polymerizable monomer (D).
Examples of the radical polymerizable monomer (D) include acrylic acid, methacrylic acid, mono(meth)acrylate compounds, poly(meth)acrylate compounds, monovinyl compounds, and polyvinyl compounds, which are exemplified for the compound (B).
The constituent unit derived from the radical polymerizable monomer (D) forming the polymer chain may be one type or two or more types.

The polymer compound of the present invention can be obtained, for example, by radically polymerizing a radically polymerizable monomer (D) using a chain transfer agent (F).
The amount of the chain transfer agent (F) used during the radical polymerization of the radical polymerizable monomer (D) is preferably 0.2 to 20 parts by mass, more preferably 0.6 to 15 parts by mass, per 100 parts by mass of the total amount of the radical polymerizable monomer (D).

Examples of the radical polymerization include solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization.

Examples of polymerization solvents used in the radical polymerization include aromatic hydrocarbon solvents (toluene, ethylbenzene, xylene, etc.), aliphatic hydrocarbon solvents (pentane, hexane, heptane, octane, cyclohexane, etc.), ketone solvents (acetone, methyl isobutyl ketone, methyl ethyl ketone, etc.), ester solvents (butyl acetate, etc.), and alcohol solvents (methanol, ethanol, etc.).
The polymerization solvent may be one type or two or more types.
The amount of the polymerization solvent used is preferably 50 to 500 parts by mass, more preferably 100 to 300 parts by mass, per 100 parts by mass of the total amount of the radical polymerizable monomer (D).

Examples of the radical polymerization initiator used in the radical polymerization include peroxides such as dibenzoyl peroxide and tert-butyl permaleate, and azo compounds such as 2,2'-azobisisobutyronitrile and azobisisovaleronitrile.
The radical polymerization initiator may be one type or two or more types.
The amount of the radical polymerization initiator used is preferably 0.0001 to 10 parts by mass, more preferably 0.001 to 1 part by mass, per 100 parts by mass of the total amount of the radical polymerizable monomer (D).

The polymerization temperature for the radical polymerization can be set as appropriate. For example, a temperature range of -100 to 250°C is preferred, as this is an appropriate temperature range for use with the radical polymerization initiator.

The polymerization time for the radical polymerization can be set appropriately, for example, from 0.5 to 48 hours.

As described above, in the polymer compound of the present invention, a plurality of polymer chains are linked by the divalent or higher linking group, and the divalent or higher linking group has either or both of a thiol group and a thioether structure, and the ratio (absolute _Mw /relative _Mw ) is controlled within a specific range.
Furthermore, when the divalent or higher linking group has a thiol group, the thiol group of the divalent or higher linking group has an acid dissociation constant pKa value with respect to water of 8.0 or less, and when the divalent or higher linking group has a thioether structure and the divalent or higher linking group has two or more thioether structures, the shortest distance between sulfur atoms in the thioether structures is 300 or more in terms of molecular weight.
This exerts the effect of suppressing the viscosity of a solution containing the polymer compound of the present invention from increasing.

[Composition and method for producing the same]
The composition of the present invention is a composition containing, as a main component, a compound (E) having a moiety derived from a polyfunctional thiol compound (A) and a moiety derived from a compound (B) having a reactive group that reacts with a thiol group, and is a composition that satisfies formulas (11) and (12).
r×(f _A −1)×(f _B −1)<1.2 (11)
r=(f _B ×y)/(f _A ×x) (12)
In formula (11) and formula (12), _fA is the average number of thiol groups per molecule of the polyfunctional thiol compound (A), and _fB is the average number of reactive groups per molecule of the compound (B). _fA is 2.0 or more, and _fB is 1.2 or more, except for the case where only the compound (A) has two thiol groups and only the compound (B) has two reactive groups.
In formula (12), x and y are x and y, respectively, when the molar ratio of the moiety derived from the polyfunctional thiol compound (A) to the moiety derived from the compound (B) is x:y.

The composition of the present invention has excellent solubility in polymerization solvents and monomers, and can be suitably used as a chain transfer agent in the production of the above-mentioned polymer compounds. Furthermore, the composition of the present invention has the effect of suppressing the increase in viscosity of the solution to which it is added.

The compound (E) may be a single compound satisfying the formulas (11) and (12), or may be a group of multiple compounds satisfying the formulas (11) and (12).
The composition of the present invention contains the compound (E) as a main component. That is, it is sufficient that the composition contains the compound (E) in the largest amount by mass ratio, and the composition may contain, in addition to the compound (E), for example, unreacted polyfunctional thiol compound (A) or compound (B), etc.
The composition of the present invention preferably contains 50% by mass or more of compound (E) relative to the total mass of the composition, more preferably 70% by mass or more, even more preferably 80% by mass or more, and still more preferably 90% by mass or more.

The compound (E) has a moiety derived from the polyfunctional thiol compound (A) and a moiety derived from the compound (B) having a reactive group that reacts with a thiol group.
In the compound (E), the moiety derived from the polyfunctional thiol compound (A) means a moiety formed based on the polyfunctional thiol compound (A) in the structure formed when the polyfunctional thiol compound (A) reacts with the compound (B) having a reactive group that reacts with a thiol group.
Similarly, in compound (E), the moiety derived from compound (B) having a reactive group that reacts with a thiol group means a moiety formed based on compound (B) in the structure formed when polyfunctional thiol compound (A) reacts with compound (B) having a reactive group that reacts with a thiol group.
In the present invention, the moiety derived from the polyfunctional thiol compound (A) may be referred to as a structural unit composed of the polyfunctional thiol compound (A).
In the present invention, a moiety derived from the compound (B) having a reactive group that reacts with a thiol group may be referred to as a structural unit consisting of the compound (B) having a reactive group that reacts with a thiol group.

The thioether structure may include a moiety having the structure shown in formula (1), which improves heat resistance.

Compound (E) preferably has a thioether structure, and more preferably has a structure represented by formula (1), in that it is easy to produce and a variety of compounds can be easily obtained.
When the compound (E) has a thioether structure, the polymer compound obtained by polymerization using the compound (E) as a chain transfer agent tends to have excellent long-term thermal stability.
Furthermore, when the compound (E) has a thioether structure, the polymer compound obtained by polymerization using the compound (E) as a chain transfer agent tends to have excellent mechanical properties.

The compound (E) preferably has at least one thiol group per molecule.
The average number of thiol groups per molecule of the compound (E) is not particularly limited to a lower limit, but is preferably 3 or more, and more preferably 4 or more.
On the other hand, the upper limit of the average number of thiol groups per molecule of the compound (E) is not particularly limited, but is preferably 50 or less, and more preferably 30 or less.
When the average number of thiol groups per molecule of the compound (E) is equal to or greater than the above lower limit, the number of branches of the polymer obtained when the composition of the present invention is used as a chain transfer agent is likely to be sufficient, and the heat resistance of the polymer is also increased.
When the average number of thiol groups per molecule of the compound (E) is equal to or less than the upper limit, the solution viscosity of the polymer obtained when the composition of the present invention is used as a chain transfer agent can be reduced.

The above description can be applied to the polyfunctional thiol compound (A) and the compound (B) having a reactive group that reacts with a thiol group.

The composition of the present invention satisfies formulas (11) and (12).
r×(f _A −1)×(f _B −1)<1.2 (11)
r=(f _B ×y)/(f _A ×x) (12)
In formula (11) and formula (12), _fA is the average number of thiol groups per molecule of the polyfunctional thiol compound (A), and _fB is the average number of reactive groups per molecule of the compound (B). _fA is 2.0 or more, and _fB is 1.2 or more, except for the case where only the compound (A) has two thiol groups and only the compound (B) has two reactive groups.
In formula (12), x and y are x and y, respectively, when the molar ratio of the moiety derived from the polyfunctional thiol compound (A) to the moiety derived from the compound (B) is x:y.

The composition of the present invention has excellent solubility in polymerization solvents and monomers by satisfying formulas (11) and (12). The reason for this is presumed to be as follows, for example. When the values of (f _A -1) and (f _B -1) in formula (11) are small, the number of reaction sites during the production of the composition is reduced, so the molecular weight of the composition does not become too large, and the composition has excellent solubility. When the value of r is small, the number of thiol groups in the product increases, the number of branches in the composition increases, and the solubility improves.
Note that, while attempting to reduce all of the values of r, (f _A -1), and (f _B -1) places significant constraints on the raw materials used for production, etc., in the present invention, it is not necessary to reduce all of the values, as long as the raw materials used for production of the composition are adjusted taking into consideration equation (11), i.e., the product of r×(f _A -1)×(f _B -1), to be less than 1.2. From this perspective, the present invention also has the advantage of providing a high degree of freedom in the selection of raw materials, etc., in the production of the composition.

The value of formula (11) is 1.2 or less. The present inventors have found that in a composition containing compound (E), when formula (11) is 1.2 or less, the composition has excellent solubility in polymerization solvents and monomers and is also suitable as a chain transfer agent. When the value of formula (11) exceeds 1.2, the composition is prone to gelation or hardening, is insoluble in solvents, and is incompatible with other resins, etc.
The upper limit of the value of formula (11) is 1.2 or less, preferably 1.15 or less, and more preferably 1.1 or less. On the other hand, the lower limit of the value of formula (11) is not particularly limited, but is preferably 0.1 or more, and more preferably 0.3 or more. When the value of formula (11) is equal to or less than the upper limit of the above range, the solubility in the polymerization solvent and monomer is better. When the value of formula (11) is equal to or more than the lower limit of the above range, the number of unreacted functional groups per molecule of the obtained compound (E) increases, making it easier to use as a chain transfer agent. For example, when the composition of the present invention containing compound (E) is used as a chain transfer agent, the solution viscosity of the obtained polymer can be reduced, improving handleability.

The lower limit of the average number _fA of thiol groups per molecule of the polyfunctional thiol compound (A) is 2.0 or more, preferably 2.5 or more, and more preferably 3.0 or more. On the other hand, the upper limit of the average number _fA of thiol groups per molecule of the polyfunctional thiol compound (A) is not particularly limited, but from the viewpoint of preventing insolubilization of the multi-branched thiol compound (A), it is preferably 9.0 or less, and more preferably 6.0 or less.

The lower limit of the average number _fB of reactive groups per molecule of compound (B) is 1.2 or more, preferably 1.3 or more, and more preferably 1.5 or more. On the other hand, the upper limit of the average number _fB of reactive groups per molecule of compound (B) is not particularly limited, but from the viewpoint of reducing unreacted thiol groups remaining in the product, it is preferably 6.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less.

However, this does not apply when only compound (A) having two thiol groups and only compound (B) having two reactive groups are used. In other words, when a multi-branched thiol compound (A) having two thiol groups is reacted with only compound (B) having two reactive groups that react with thiol groups, the resulting compound (E) will be almost linear. For this reason, when compound (E) is used as a chain transfer agent, the number of branches in the resulting polymer will be insufficient.

_fA + _fB is preferably greater than 4.0, more preferably equal to or greater than 4.5, and even more preferably equal to or greater than 5.0. When _fA + _fB is greater than 4.0, the resulting compound (E) has more branches, and the solubility of the composition is improved.
Furthermore, f _A +f _B is preferably 12.0 or less, and more preferably 10.0 or less.
Furthermore, f _A +f _B is preferably more than 4.0 and not more than 12.0, and more preferably 4.5 to 10.0.

The ratio (x/y) of the number of moles x of the moiety derived from the polyfunctional thiol compound (A) to the number of moles y of the moiety derived from the compound (B) is not particularly limited to a lower limit, but is preferably 0.5 or more, more preferably 0.8 or more, and even more preferably 1.0 or more. On the other hand, the ratio (x/y) has no particular upper limit, but is preferably 8.0 or less, more preferably 6.0 or less, and even more preferably 4.0 or less.
It is preferable to set the ratio (x/y) to the above lower limit or more and the above upper limit or less from the viewpoint of the number of branches and solubility of the compound (E). In addition, the compound (E) is likely to have a thiol group and is therefore easily usable as a chain transfer agent.

The relative _Mw of the composition of the present invention is preferably 1,000 or more, more preferably 1,000 to 50,000, and even more preferably 2,000 to 20,000, from the viewpoint of solubility and the like.
The relative _Mw of the composition is a value calculated as polymethyl methacrylate as measured by gel permeation chromatography (GPC). In the differential molecular weight distribution obtained by GPC measurement of the composition of the present invention, typically, multiple molecular weight peaks are observed in the molecular weight region of 1,000 or more. In this case, it is preferable that all of these multiple molecular weight peaks are within the above-mentioned range.

As a method for producing the composition of the present invention, it is preferable to react the polyfunctional thiol compound (A) with the compound (B) having a reactive group that reacts with a thiol group under conditions that satisfy the formulas (13) and (14).
r'×(f _A -1)×(f _B -1)<1.2 (13)
r'=(f _B ×y')/(f _A ×x')...(14)
In formula (13) and formula (14), _fA is the average number of thiol groups per molecule of the polyfunctional thiol compound (A), and _fB is the average number of reactive groups per molecule of the compound (B). _fA is 2.0 or more, and _fB is 1.2 or more, except for the case where only the compound (A) has two thiol groups and only the compound (B) has two reactive groups.
In the formula (14), x' and y' respectively represent x' and y' when the molar ratio of the polyfunctional thiol compound (A) to the compound (B) is x':y'.

x', y', and r' are the values at the time of charging for the reaction, but when the composition after the reaction is used as is as a "composition containing compound (E)", they are equal to x, y, and r, respectively.

The preferred ranges of f _A and f _B in formula (13) are the same as those of f _A and f _B in formula (11), and the preferred range of r′×(f _A −1)×(f _B −1) is also the same as that of r×(f _A −1)×(f _B −1) in formula (11).
The preferred ratios of x' and y' are the same as the preferred ratios of x and y in formula (11), and the preferred value of r' is the same as the preferred value of r in formula (11).

Examples of the polyfunctional thiol compound (A) and compound (B) include the polyfunctional thiol compound (A) and compound (B) described above, respectively.

The resulting composition preferably contains compound (E) as the main component. It may also contain unreacted polyfunctional thiol compound (A) and compound (B).

The conditions for this reaction can be the same as those for obtaining the chain transfer agent (F) by the addition polymerization reaction of the polyfunctional thiol compound (A) and the compound (B).
Although there is no particular limitation to this reaction, it is preferable to carry out the reaction in the presence of a catalyst (C). As the catalyst (C), the same description as above can be applied as is.

Furthermore, the composition may be used in combination with additives such as pigments, ultraviolet absorbers, adhesion promoters, release agents, stabilizers, antioxidants, antifoaming agents, plasticizers, and viscosity modifiers, if necessary.
The amount of the additive used is preferably less than 5% by mass, more preferably less than 3% by mass, and even more preferably less than 1% by mass, based on the total mass of the composition.

As explained above, in the present invention, when a composition containing compound (E) satisfies the above conditions, it has a large number of branches, does not form a crosslinked polymer network, and has excellent solubility in polymerization solvents and monomers.

The composition of the present invention can be suitably used as a chain transfer agent in a radical polymerization reaction system. Branched polymers produced using the composition of the present invention as a chain transfer agent have a large number of branches, so even if they have a high molecular weight, the viscosity of the solution to which they are added can be maintained low. Therefore, for example, a paint containing the branched polymer can achieve both improved coating film properties and excellent paintability. Furthermore, this branched polymer also has the effect of excellent heat resistance.
Furthermore, when the composition containing the compound (E) of the present invention is added to a thermoplastic resin, it has the effect of improving the heat resistance of the thermoplastic resin and suppressing the viscosity of the solution to which it is added. Therefore, the composition may be used as an additive to paints, etc.

[Resin composition]
The resin composition of the present invention includes the above-described polymer compound or composition and a thermoplastic resin, such as polyamide, polyester, polycarbonate, polyethersulfone, polyphenylene ether, polyphenylene sulfide, polyetheretherketone, polyetherketone, polyimide, polytetrafluoroethylene, polyether, polyolefin, liquid crystal polymer, polyarylate, polysulfone, polyacrylonitrilestyrene, polystyrene, polyacrylonitrile, polymethyl methacrylate (PMMA), polyglycidyl methacrylate (PGMA), and acrylonitrile-butadiene-styrene copolymer (ABS).
The thermoplastic resin is preferably an addition polymerization polymer such as polysulfone, polyacrylonitrile styrene, polystyrene, polyacrylonitrile, polymethyl methacrylate (PMMA), polyglycidyl methacrylate (PGMA), or acrylonitrile-butadiene-styrene copolymer (ABS).
The thermoplastic resins may be used alone or in combination of two or more.

The present invention will be explained in more detail below using examples. However, the present invention is not limited to the examples described below, and various modifications are possible without departing from the gist of the present invention.

[Raw materials]
The raw materials used in the examples and comparative examples and their abbreviations are shown below.

<Polyfunctional thiol compound (A)>
PEMP: Pentaerythritol tetrakis(3-mercaptopropionate) (manufactured by SC Organic Chemicals)
PEMA: Pentaerythritol tetrakis(2-mercaptoacetate) (Tokyo Chemical Industry Co., Ltd.)

<Compound (B)>
C6DA: 1,6-hexanediol diacrylate (manufactured by Mitsubishi Chemical Corporation)
M260: Polyethylene glycol diacrylate (Aronix (registered trademark) M260, manufactured by Toagosei Co., Ltd.)

<Catalyst (C)>
TPP: Triphenylphosphine (Tokyo Chemical Industry Co., Ltd.)

<Radical Polymerizable Monomer (D)>
MMA: Methyl methacrylate (Acrylate M, manufactured by Mitsubishi Chemical Corporation)

<Solvent>
DMF: dimethylformamide (Fujifilm Wako Pure Chemical Industries, Ltd.)
Diglyme: diethylene glycol dimethyl ether (Tokyo Chemical Industry Co., Ltd.)

[Measurement and evaluation methods]
<Relative _Mw , Absolute _Mw , Absolute _Mw /Relative _Mw >
(Relative _Mw )
The relative _Mw of the polymer compound was measured by gel permeation chromatography (GPC) under the following conditions:
Apparatus: HLC-8220 (manufactured by Tosoh Corporation)
Column: TSK GUARD COLUMN SUPER H-H (4.6 x 35 mm, manufactured by Tosoh Corporation) and two TSK-GEL SUPER HM-H (6.0 x 150 mm, manufactured by Tosoh Corporation) connected in series. Detector: Refractive index (RI) detector. Column and detector temperature: 40°C.
Eluent: tetrahydrofuran Flow rate: 0.6 mL/min Sample concentration: 2 mg/mL (tetrahydrofuran solution)
Standard substance: polymethyl methacrylate (Polymer Laboratories; Mp (peak molecular weight) = 141,500, 55,600, 11,100, 1,590)

(Absolute M _w )
The absolute Mw of the polymer compound was measured by gel permeation chromatography (GPC) under the following conditions:
Apparatus: General-purpose HPLC Prominence (Shimadzu Corporation)
Column: One guard column (Showa Denko K.K.) and two analytical columns (Showa Denko K.K.) connected in series. Detector: Multi-angle light scattering detector (((MA)LS) DAWN HELEOS II (Wyatt Corporation)
Column and detector temperature: 35°C
Eluent: tetrahydrofuran Flow rate: 1.0 mL/min Sample concentration: 2 mg/mL (tetrahydrofuran solution)
Analysis software: OmniSEC (Malvern Panalytical, included with the device)

(Absolute _Mw /Relative _Mw )
The measured absolute _Mw was divided by the measured relative _Mw to calculate absolute _Mw /relative _Mw .

<pKa of thiol group of linking group>
The pKa of the thiol group of the linking group of the polymer compound was calculated using Advanced Chemistry Development (ACD/Labs) Software.

<Distance between thioether structures>
The distance between thioether structures in the linking group of the polymer compound was defined as the molecular weight obtained by adding 2 (the molecular weight of two hydrogen atoms) to the molecular weight of the compound (B) used.

<Solution viscosity>
The solution viscosity of the polymer compound was measured by the following method.
(1) The polymer compounds of the Examples and Comparative Examples were dissolved in butyl acetate to prepare solutions with a solid content (polymer compound) concentration of 40% by mass.
(2) The viscosity of the prepared polymer compound solution was measured at room temperature (25° C.) using an E-type viscometer.

<Proportion of branched polymers in polymer compounds>
The proportion of branched polymer in the polymer compound was calculated by the following method.
The reprecipitated polymer compound was subjected to GPC light scattering measurement to determine the intrinsic viscosity η calculated from the absolute molecular weight Mw and the radius of gyration Rg. An MH-plot was then created, with the horizontal axis representing the logarithm of the absolute molecular weight Mw and the vertical axis representing the logarithm of the intrinsic viscosity η. The MH-plot of the polymer compound obtained in the present invention has a large slope on the low molecular weight side and a small slope on the high molecular weight side. This indicates that the low molecular weight component is dominated by linear polymers, while the high molecular weight component is dominated by branched polymers. Therefore, the polymer present on the high molecular weight side from the point where the slope of the MH-plot on the low molecular weight side intersects with the slope of the MH-plot on the high molecular weight side was defined as a branched polymer, and the proportion [%] of branched polymers relative to the total amount was calculated.

<Degree of branching>
The branching degree of the polymer compound was calculated by the following method.
The branched polymer can be decomposed into linear polymers by applying a known transesterification method to the polymer compound after reprecipitation, for example, a method of performing transesterification by adding a Lewis acid such as a metal alkoxide and an alcohol. The degree of branching was calculated using the Mp (peak top molecular weight) of the polymer compound before the transesterification reaction and the Mp of the polymer compound after the transesterification reaction according to the following formula:
Degree of branching = (peak top molecular weight before reaction)/(peak top molecular weight after reaction)

[Production Example 1]
To 10 g of PEMA, which is the polyfunctional thiol compound (A), 0.1 g of finely crushed TPP was added as the catalyst (C), and the mixture was heated to 80°C with stirring until homogeneous and completely dissolved. To the resulting mixture, 3.49 g of C6DA, which is the compound (B), was added, and the molar ratio of PEMA to C6DA was adjusted to PEMA:C6DA = 1.5:1.0, followed by stirring at room temperature (25°C) to obtain chain transfer agent (F-1).

[Production Example 2]
A chain transfer agent (F-2) was produced in the same manner as in Production Example 1, except that 10.8 g of M260 was used as compound (B) instead of 3.49 g of C6DA.

[Production Example 3]
A chain transfer agent (F-3) was produced in the same manner as in Production Example 1, except that 11.3 g of PEMP was used as compound (A) instead of 10 g of PEMA, and 10.8 g of M260 was used as compound (B) instead of 3.49 g of C6DA.

[Production Example 4]
A chain transfer agent (F-4) was produced in the same manner as in Production Example 1, except that PEMP was used instead of PEMA as compound (A) , and that C6DA and EHA were used instead of C6DA as compound (B), and the molar ratio of PEMP, C6DA, and EHA was PEMP:C6DA:EHA=1.5:1.0:1.0.

[Example 1]
A 50 mL Schlenk flask equipped with a stirrer and a nitrogen inlet tube was charged with 100 parts by mass of methyl methacrylate (MMA) as the radical polymerizable monomer (D), 3.17 parts by mass of the chain transfer agent (F-1) obtained in Production Example 1 as the chain transfer agent (F) relative to 100 parts by mass of MMA, and 0.3 mol % of 2,2'-azobisbutyronitrile (AIBN) as a polymerization initiator relative to the radical polymerizable monomer (D), and Diglyme was further added as a solvent. The radical polymerizable monomer (D), chain transfer agent (F-1), polymerization initiator, and solvent were mixed in the Schlenk flask to prepare a mixed solution with a solids concentration (radical polymerizable monomer (D), chain transfer agent (F-1), and polymerization initiator) of 0.5% by mass. The prepared mixed solution was heated to 80°C while stirring under a nitrogen atmosphere. The mixed solution was heated and stirred for 5 hours, and then reprecipitated using hexane as a poor solvent to obtain a polymer compound.
The relative Mw, absolute Mw, absolute Mw/relative Mw, pKa of the thiol group in the linking group, distance between thioether structures, solution viscosity, and degree of branching of the resulting polymer compound were measured or calculated. The results of the measurements or calculations are shown in the corresponding columns in Table 1.

[Examples 2 and 3]
A polymer compound was obtained in the same manner as in Example 1, except that the amount of chain transfer agent (F-1) was changed to 5.33 parts by mass (Example 2) or 6.52 parts by mass (Example 3) per 100 parts by mass of the radical polymerizable monomer (D).
The relative Mw, absolute Mw, absolute Mw/relative Mw, pKa of the thiol group in the linking group, distance between thioether structures, solution viscosity, proportion of branched polymers, and degree of branching of the obtained polymer compound were measured or calculated. The results of the measurement or calculation are shown in the corresponding columns in Table 1.

[Examples 4 to 6]
A polymer compound was obtained in the same manner as in Example 1, except that the chain transfer agent (F) was changed to the chain transfer agent (F-2) obtained in Production Example 2 and the amount of the chain transfer agent (F) added was changed to 4.89 parts by mass (Example 4), 8.21 parts by mass (Example 5), or 10 parts by mass (Example 6) per 100 parts by mass of the radical polymerizable monomer (D).
The relative Mw, absolute Mw, absolute Mw/relative Mw, pKa of the thiol group in the linking group, distance between thioether structures, solution viscosity, proportion of branched polymers, and degree of branching of the obtained polymer compound were measured or calculated. The results of the measurement or calculation are shown in the corresponding columns in Table 1.

[Examples 7 to 9]
A polymer compound was obtained in the same manner as in Example 1, except that the chain transfer agent (F) was changed to the chain transfer agent (F-3) obtained in Production Example 3, the amount of the chain transfer agent (F) was changed to 5.29 parts by mass (Example 7), 8.9 parts by mass (Example 8), or 10.9 parts by mass (Example 9) per 100 parts by mass of the radical polymerizable monomer (D), DMF was used as the solvent, and methanol was used as the poor solvent.
The relative Mw, absolute Mw, absolute Mw/relative Mw, pKa of the thiol group in the linking group, distance between thioether structures, solution viscosity, proportion of branched polymers, and degree of branching of the obtained polymer compound were measured or calculated. The results of the measurement or calculation are shown in the corresponding columns in Table 1.

[Comparative Examples 1 to 3]
A polymer compound was obtained in the same manner as in Example 1, except that the chain transfer agent (F) was changed to the chain transfer agent (F-4) obtained in Production Example 4, the amount of the chain transfer agent (F) added was changed to 3.44 parts by mass (Comparative Example 1), 5.57 parts by mass (Comparative Example 2), or 7.04 parts by mass (Comparative Example 3) per 100 parts by mass of the radical polymerizable monomer (D), DMF was used as the solvent, and ethanol was used as the poor solvent.
The relative Mw, absolute Mw, absolute Mw/relative Mw, pKa of the thiol group in the linking group, distance between thioether structures, solution viscosity, proportion of branched polymers, and degree of branching of the obtained polymer compound were measured or calculated. The results of the measurement or calculation are shown in the corresponding columns in Table 1.

The following can be said from the above-described Examples and Comparative Examples.
It was shown that the Examples in which the pKa of the thiol group of the linking group was 8.0 or less had a higher degree of branching and a higher proportion of branched polymers than the Comparative Examples in which the pKa exceeded 8.0.
It was shown that the Examples in which the distance between thioether structures (the minimum value of the distance between thioether structures in terms of molecular weight) was 300 or more had a higher degree of branching and a higher proportion of branched polymers than the Comparative Examples in which the distance between thioether structures was less than 300.
It was also shown that polymer compounds with a similar molecular weight and a high degree of branching or a high proportion of branched polymers exhibited a reduced solution viscosity.

Claims (7)

A polymer compound in which a plurality of polymer chains are linked by a divalent or higher linking group,
the divalent or higher valent linking group has both a thiol group and a thioether structure,
the ratio of absolute weight average molecular weight (absolute Mw) to relative weight average molecular weight (relative Mw) (absolute Mw/relative Mw) is 1.25 or more;
the divalent or higher linking group has an acid dissociation constant pKa value with respect to water of 8.0 or less;
the divalent or higher valent linking group has two or more thioether structures, and the shortest distance between sulfur atoms in the thioether structures is 300 or more in terms of molecular weight;
High molecular compound. The polymer compound according to claim 1 , wherein the divalent or higher valent linking group includes a structure represented by formula (1):
In formula (1), ^R1 and ^R2 each independently represent one selected from the group consisting of a hydrogen atom, a monovalent hydrocarbon group, a hydroxyl group, and a monovalent electron-withdrawing group; ^R3 represents one selected from the group consisting of an oxygen atom, a divalent hydrocarbon group, and a divalent electron-withdrawing group; and -* represents a bond. 3. The polymer compound according to claim 1, wherein the divalent or higher valent linking group has 1 to 300 thiol groups per molecule of the polymer compound. The polymer compound according to any one of claims 1 to 3, wherein the absolute Mw/relative Mw is 1.25 to 2.10 . A method for producing the polymer compound according to any one of claims 1 to 4, comprising:
a step of reacting a polyfunctional thiol compound (A) with a compound (B) having a reactive group that reacts with a thiol group to obtain a chain transfer agent (F) having a thiol group;
and a step of polymerizing a vinyl compound in the presence of the chain transfer agent (F) having a thiol group and a radical polymerization initiator to obtain a polymer compound,
the acid dissociation constant pKa of the thiol group contained in the polyfunctional thiol compound (A) with water is 8.0 or less;
the molecular weight of the compound (B) having a reactive group that reacts with a thiol group is 300 or more;
A method for producing a polymer compound. The method for producing a polymer compound according to claim 5 , wherein the reactive group that reacts with a thiol group is at least one selected from the group consisting of an acrylate group and a glycidyl group. A resin composition comprising the polymer compound according to any one of claims 1 to 4 and a thermoplastic resin.