JP2847242B2 - Method for producing carboxyl group-containing macromonomer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Object of the Invention [Industrial Application Field] The present invention relates to a macromonomer which is an effective material for multifunctionalization of a polymer material, particularly an industrially useful reactive group. It relates to a method for producing a macromonomer containing
The macromonomer obtained by the present invention and the graft polymer produced using the macromonomer as a raw material are useful as materials for paints, adhesives, molding materials and the like, and as modifiers for these materials, and polymer materials It will be an influential material for further multi-functionalization of paints, adhesives,
It is widely used in various industries that use molding materials and the like.

[Conventional technology]

Attempts to use block polymers and graft polymers as a means of achieving multifunctional polymer materials have been made for some time, and there is also known a method of using macromonomers as a method of synthesizing a graft polymer whose structure is clearly regulated. Have been. The macromonomer means an oligomer or polymer having a polymerizable functional group at a molecular terminal, and is an abbreviation for Macromolecure Monomer.

The methods for synthesizing macromonomers are roughly classified into a method using living polymerization centering on ionic polymerization and a chain transfer polymerization method centering on radical polymerization.

In both cases, the second-stage reaction of introducing a polymerizable functional group into the molecular terminal after the polymerization reaction is important, for example, a hydroxyl group and an isocyanate group, a hydroxyl group and an acid chloride, a carboxyl group and an epoxy group, and a carboxylate. A method of introducing a polymerizable functional group using an ionic reaction such as chloride and chloride has been widely adopted.

However, when a polymer obtained by a living polymerization method or a chain transfer polymerization method is used and a polymerizable functional group introduction reaction (reaction in the second stage) is further performed at the molecular end, the reactivity of the main chain of the polymer is reduced. When a functional group such as a carboxyl group, a hydroxyl group, an epoxy group, an isocyanate group, or a carboxylate is present, various side reactions occur, thereby deteriorating the performance as a macromonomer. Compound formation).

More specifically, for example, a method for producing a macromonomer by a radical chain transfer method, which is capable of producing a variety of macromonomers that are the most advantageous industrially, is usually carried out by using mercaptopropionic acid or the like as a chain transfer agent. In this method, a macromonomer is obtained by synthesizing a carboxyl-type low to medium molecular weight polymer (hereinafter referred to as a prepolymer) and further reacting it with glycidyl (meth) acrylate or the like. When functional groups such as carboxyl groups and hydroxyl groups are present in the main chain of the polymer, a reaction between these functional groups and glycidyl groups occurs, and a polymerizable functional group is introduced into the main chain, resulting in cross-linkable polyfunctionality. It becomes a compound, and when such a compound is polymerized with other monomers as a macromonomer, it tends to gel and is almost used Not come.

On the other hand, consumers of macromonomers, for example, manufacturers of paints, coating materials, adhesives, molding materials, medical materials, electronic materials, etc., often require multifunctional materials in recent years.
Want to impart reactivity such as a crosslinking reaction to a graft polymer obtained by polymerizing a macromonomer with other monomers.
In order to improve the dispersibility of inorganic substances, and to use a macromonomer as a hydrophilic segment (in this case, a graft polymer whose main component is a macromonomer as a component), a functional group such as a carboxyl group is contained. There is an increasing demand for macromonomers to be used.

Conventionally, when a graft polymer containing a reactive group such as a carboxyl group is produced, the graft polymer is reacted with the macromolecule in the trunk segment, that is, instead of producing the reactive polymer in the branch segment, that is, the macromonomer main chain. It is customary to use a monomer containing a reactive group such as a carboxyl group as the monomer. This is based on the restrictions on macromonomer synthesis described above.

However, generally, the reactive group present in the trunk segment of the graft polymer is inferior in reactivity due to the low mobility of the molecule, and an excess of reactive groups must be used to obtain the required reactivity. However, there is a problem that the physical properties of the material tend to be reduced and problems during the production are likely to occur.

Furthermore, since conventional macromonomers are basically lipophilic, they also have the problem that they are almost unusable from the viewpoint of solubility in alcoholic or aqueous solution polymerization.

Therefore, a demand for a macromonomer having a reactive group such as a carboxyl group (particularly, a vinyl polymerization type macromonomer) is very large.

[Problems to be solved by the invention]

The present inventors have conducted various studies with an object of obtaining a macromonomer having a reactive group in order to satisfy the above demand.

(B) Configuration of the Invention [Means for Solving the Problems] The present inventors utilize the selective decomposition reactivity of a tertiary alkyl ester group to form a carboxyl group in the main chain of a vinyl polymerizable functional group. The present inventors have found that a macromonomer containing a group only at the terminal can be easily produced and that the above-mentioned demand can be satisfied, and the present invention has been completed.

That is, the present invention is a linear polymer comprising a radically polymerizable vinyl monomer unit having a tertiary alkyl ester group and another radically polymerizable vinyl monomer unit, and one terminal thereof. By maintaining a macromonomer having only a vinyl polymerizable functional group (hereinafter referred to as a tertiary alkyl ester group-containing macromonomer) at a temperature of from 150 ° C. to 150 ° C. in the presence of an acid catalyst, the tertiary alkyl ester group is A method for producing a carboxyl group-containing macromonomer, which comprises decomposing an alkene based on a secondary alkyl and a carboxyl group.

 Hereinafter, the present invention will be described in more detail.

The tertiary alkyl ester group-containing macromonomer used in the present invention is a prepolymer having a tertiary alkyl ester group, which is obtained by radically polymerizing a radically polymerizable vinyl monomer described below with reference to specific examples. Can be produced by bonding a vinyl polymerizable functional group to one end of the polymer.

Method for producing tertiary alkyl ester group-containing macromonomer Radical containing tertiary alkyl ester group such as tertiary alkyl ester of unsaturated carboxylic acid such as (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, carboxyl-substituted styrene derivative Polymerizable monomers or vinyl esters of organic acids such as vinyl acetate with them, vinyl aromatic compounds such as styrene and styrene substituents, (meth) acrylates, (meth) acrylonitrile, N-vinylpyrrolidone and N-vinylcaprolactam Radical polymerizable monomers such as N-vinyl compounds, unsaturated chlorides such as vinyl chloride and vinylidene chloride, in the presence of a mercaptan-based chain transfer agent having a functional group, and a prepolymer having a functional group at a terminal. And then react with the functional group A vinyl compound having both the reactive group vinyl polymerizable group and the prepolymer are reacted to obtain a tertiary alkyl ester group-containing macromonomer.

As the unsaturated carboxylic acid in the tertiary alkyl ester group of the unsaturated carboxylic acid, (meth) acrylic acid is preferably used. A preferred tertiary alkyl group is a tertiary butyl group.

The preferred use amount of the monomer having a tertiary alkyl ester group in the radical polymerizable monomer when synthesizing the prepolymer is 0.1% or more,
1.0% or more. If the amount of the tertiary alkyl ester group-containing monomer is 0.1% or less, the carboxyl group in the finally obtained carboxyl group-containing macromonomer may be too small to add reactivity. The use amount of the tertiary alkyl ester group-containing monomer may be determined according to the carboxyl group content to be introduced into the target carboxyl group-containing macromonomer, and may be 100%, in other words, the tertiary alkyl ester group-containing monomer alone. It can also be a prepolymer.

As the monomers other than the monomer having a tertiary alkyl ester group, (meth) acrylic acid esters, which are less likely to cause side reactions during the second-stage polymerizable group introduction reaction and which can easily control the molecular weight by a chain transfer reaction, (Meth) acrylonitrile and styrene derivatives are preferably used.

These monomers may be used alone or in combination.

As a functional group of the mercaptan-based chain transfer agent, a carboxyl group is generally used in relation to a vinyl compound to be reacted later. Examples of the mercaptan-based chain transfer agent having a carboxyl group include mercaptoacetic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid and the like.

As a polymerization method in the production of the prepolymer, any method of a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and an emulsion polymerization method may be used in the presence or absence of a radical polymerization initiator.

As the radical polymerization initiator used at this time, a usual azo initiator or peroxide initiator can be used, but an azo initiator is preferable in order to avoid a reaction with a mercaptan compound. As the azo-based initiator, 2,2-azobisisobutyronitrile (hereinafter abbreviated as AIBN), 4,4-azobis-4
-Cyanovaleric acid (hereinafter abbreviated as ACVA), 1
-Azobis-1-cyclohexanecarbonitrile (hereinafter referred to as "azobis-1-cyclohexanecarbonitrile")
ACHN is abbreviated.

When the terminal functional group of the prepolymer is a carboxyl group, a compound having both an epoxy group and a vinyl polymerizable group having high reactivity with the carboxyl group is exemplified as a vinyl compound to be reacted with the prepolymer. Examples thereof include glycidyl (meth) acrylate, allyl glycidyl ether, and chloromethylvinylbenzene, which are used in the production of a graft polymer using a finally obtained carboxyl group-containing macromonomer. It is preferable to select in consideration of copolymerizability with the body.

The reaction between a prepolymer and an epoxy group-containing vinyl compound (ie, a macromonomerization reaction by introducing a vinyl polymerizable functional group into the prepolymer) is mainly carried out in a solution using a catalyst,
It is carried out by adding a polymerization inhibitor for preventing a polymerization reaction during the reaction, if necessary.

The macromonomerization reaction is performed by heating a homogeneous solution containing the above-described prepolymer, vinyl compound having a reactive group, a catalyst, a solvent, and the like to a reaction temperature and reacting for several hours.

The amount of the reactive group-containing vinyl compound to be charged is preferably 0.8 to 5.0 times, more preferably 0.9 to 3.0 times, the mol of the terminal functional group of the prepolymer. The preparation amount is 0.
If the molar amount is less than 8 times, the purity of the end group of the produced macromonomer is low, and if the charged amount is more than 5.0 times, impurities when the finally obtained macromonomer is used as a raw material of a graft polymer or as a polymer material. And often causes inconvenience.

The reaction temperature is preferably room temperature to 150 ° C., and 50 to 100 ° C.
Is more preferred. When the reaction temperature is lower than room temperature, the reaction rate is low. When the reaction temperature exceeds 150 ° C., the vinyl monomer boils and the polymerization reaction is apt to occur extremely.

As the catalyst, tertiary amines, quaternary ammonium salts and the like can be used. The catalyst is preferably used in an amount of 0.1 to 3% by weight based on the whole reaction solution. When the amount of the catalyst is 0.1% or less, the reaction rate is slow. When the amount of the catalyst is 3% or more, the macromonomer finally obtained becomes an impurity when used as a raw material of the graft polymer or as a polymer material, and often causes inconvenience.

As the solvent, aromatic compounds such as benzene, toluene and xylene, acetates such as ethyl acetate and butyl acetate, and ketones such as methyl ethyl ketone and methyl isobutyl ketone are preferably used.

When a polymerization inhibitor is used, known radical polymerization inhibitors such as hydroquinone, handloquinone monomethyl ether, and phenothiazine may be used. In order to prevent polymerization, an oxygen-containing gas may be bubbled into the reaction solution.

The molecular weight of the macromonomer thus obtained is
It is preferably in a range that does not impair the polymerizability of the carboxyl group-containing macromonomer that is the final object, and it is preferable that the number average is 1,000 to 50,000, and 2,000
It is more preferable if it is up to 40,000. If the molecular weight is less than 1,000, the degree of polymerization as a polymer unit is too low, and when used as a raw material for the graft polymer, the physical properties of the macromonomer may not be reflected in the physical properties of the graft polymer.
If it exceeds 000, the polymerizability during the production of the graft polymer will be reduced, and disadvantages such as easy phase separation of the reaction system will easily occur.

The number average molecular weight of the macromonomer is a molecular weight in terms of polystyrene determined by gel permeation chromatography (hereinafter referred to as GPC), and the measurement conditions are as follows.

Apparatus: High-performance liquid chromatography (for example, HLC-802UR manufactured by Toyo Soda Kogyo Co., Ltd.) Column: Gel of polystyrene (for example, G4000H8 and G3000H8 manufactured by Toyo Soda Kogyo Co., Ltd.) Elution solvent: tetrahydrofuran (hereinafter abbreviated as THF) Flow rate: 1.0 ml / min Column temperature: 40 ° C Detector: RI detector Decomposition reaction of tertiary alkyl ester group Decomposes tertiary alkyl ester group in tertiary alkyl ester group-containing macromonomer obtained by the above method Therefore, in the present invention, the macromonomer is maintained at room temperature to 150 ° C. in the presence of an acid catalyst.

In the reaction, the reaction vessel is charged with the macromonomer containing a tertiary alkyl ester group obtained above, a solvent, an acid catalyst soluble in the solvent, for example, paratoluenesulfonic acid, and, if necessary, a polymerization inhibitor, and then heated and stirred. It easily progresses. The reaction rate can be easily determined by measuring the acid value by alkali titration.

The solvent is usually selected from organic solvents that can dissolve the raw material components, but in addition to the solubility of the raw materials, the solvent should be selected in consideration of the solubility of the carboxyl group-containing macromonomer that is a decomposition product. It is preferable to use a solvent used in the production of the tertiary alkyl ester group-containing macromonomer and a mixture of such a solvent and a polar solvent such as an alcohol such as ethanol, methanol or isopropanol.

The amount of the acid catalyst such as paratoluenesulfonic acid used is preferably 0.05 to 5.0% by weight, more preferably 0.1 to 3.% by weight, based on the whole reaction solution. When the amount of the acid catalyst is less than 0.05% by weight, the reaction rate is low, and when the amount exceeds 5.0% by weight, a side reaction or deterioration of the stability of the product tends to be a problem.

If the temperature at which the macromonomer having the tertiary alkyl ester group is maintained is lower than room temperature, the decomposition reaction takes a long time, while if it exceeds 150 ° C, the polymerization reaction of the macromonomer occurs. And the purity of the resulting carboxyl group-containing macromonomer is poor. In order to suppress the polymerization reaction, a polymerization inhibitor such as hydroquinone, hydroquinone monomethyl ether, and phenothiazine may be added, or a method of bubbling an oxygen-containing gas may be employed.

In order to obtain the target carboxyl group content, it is necessary to carry out the reaction by adjusting the selection of the above-mentioned catalyst, the amount of the catalyst, the reaction temperature, the reaction time and the like. The reaction conversion of the tertiary alkyl ester group in the raw material macromonomer is set according to the target carboxyl group content, but is preferably 0.1 to 80%, more preferably 0.5 to 80%. The reaction is terminated at a rate. If the conversion is less than 0.1%, it becomes difficult to obtain an effective amount of carboxyl groups, and if it exceeds 80%, other ester bonds, especially vinyl polymerizable functional groups, may be present at the terminals by ester bonds. In this case, the ester bond may be decomposed, and the purity of the macromonomer may be reduced.

The carboxyl group-containing macromonomer produced as described above can be used as a macromonomer as it is or after removing the solvent.
It is preferable to remove the used acid catalyst by a neutralization treatment or a treatment with an anion exchange resin. When the acid catalyst remains in the macromonomer, when the macromonomer is copolymerized with another monomer, an ester bond in the polymer, particularly an ester bond adjacent to a terminal polymerizable group of the macromonomer may be decomposed.

The carboxyl group-containing macromonomer obtained as described above can be further modified by utilizing the reactivity of the carboxyl group. For example, if it is desired to make a carboxylate, it may be neutralized with an alkali substance such as sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide,
It can be modified by reacting with an alcohol compound, an epoxy compound, an amine compound, an isocyanate compound or the like.

The produced macromonomer can be used as a macromonomer as a solution or after solidification by removing a solvent.

[Action]

In general, tertiary alkyl ester groups thermally decompose at high temperatures of 100 ° C. or higher to produce carboxylic acids and olefins. At this time, it is known that the reaction proceeds even at a low temperature of 100 ° C. or less by using an acid catalyst. This reaction is excellent in selectivity as compared with, for example, a saponification reaction with an alkali, and is characterized in that only a tertiary alkyl ester group can be decomposed. The present inventors have paid attention to this point and applied the method to the production of a macromonomer to produce a novel macromonomer having excellent performance.

(Reference Examples, Examples and Comparative Examples)

Hereinafter, the present invention will be described more specifically with reference to Reference Examples, Examples, and Application Examples. In addition, all% described in each example are% by weight.
And parts represent parts by weight.

Reference Example 1 A glass flask equipped with a stirrer, a reflux condenser, a dropping funnel, a gas inlet tube and a thermometer was charged with 50 parts of t-butyl methacrylate, 6.07 parts of mercaptoacetic acid, and 50 parts of toluene, and t-butyl was added to the dropping funnel. Methacrylate 100
, 100 parts of toluene and 1.5 parts of azobisisobutyronitrile were added. The temperature of the content liquid was set to 90 ° C. by heating and heating the flask, and the solution in the dropping funnel was dropped over 3 hours. The reaction was further performed for 4 hours to obtain a carboxyl-terminated prepolymer. To this solution, 10 parts of glycidyl methacrylate, 1.5 parts of a quaternary ammonium salt, and 0.06 part of hydroquinone monomethyl ether were charged, and reacted at 90 ° C. for 8 hours under air bubbling. The reaction conversion determined from the acid value was 99.0%. Removing the solvent by vacuum drying,
Solid t-butyl methacrylate backbone macromonomer
I got 142 copies. The average molecular weight in terms of polystyrene by gel permeation chromatography,
Mn = 3200 and Mw = 6500. FIG. 1 shows the infrared absorption spectrum, and FIG. 2 shows the nuclear magnetic resonance absorption spectrum.

Reference Example 2 A macromonomer was produced in the same manner as in Reference Example 1 except that a mixed monomer of t-butyl methacrylate / methyl methacrylate = 2/8 (weight) was used instead of t-butyl methacrylate as a monomer. 145 parts of a solid t-butyl methacrylate copolymer skeleton macromonomer were obtained. The average molecular weight in terms of polystyrene determined by gel permeation chromatography was
Mn = 2700 and Mw = 5400.

Example 1 In a glass flask equipped with a stirrer, a reflux condenser, and a thermometer, 10 parts of the t-butyl methacrylate skeleton macromonomer obtained in Reference Example 1 and methyl isobutyl ketone 20 were added.
, 0.15 part of paratoluenesulfonic acid and 0.006 part of hydroquinone monomethyl ether, and reacted at 80 ° C. for 3 hours. After cooling, 0.6 parts of a commercially available anion exchange resin was added and stirred for 30 minutes. After standing overnight, the reaction solution was filtered to remove the anion exchange resin, and then dried under vacuum to obtain a solid carboxyl group-containing macromonomer. This has an acid value of 0.228 (meq / g) and a methacrylic acid unit content of 1.96%. The average molecular weight in terms of polystyrene by gel permeation chromatography is Mn = 320
0, Mw = 6300.

The resulting macromonomer was subjected to solution radical copolymerization with an equal amount of methyl methacrylate, and the GPC charts before and after polymerization were compared.The disappearance of the macromonomer peak was confirmed, indicating that the macromonomer was a high-purity macromonomer. Was done.

Example 2 A reaction and treatment were carried out in the same manner as in Example 1 except that the reaction condition was 90 ° C. for 4 hours, to obtain a solid carboxyl group-containing macromonomer. Its acid value is 2.012 (m
eq / g), giving a methacrylic acid unit content of 17.3%. The average molecular weight in terms of polystyrene measured by gel permeation chromatography was Mn = 3100 and Mw = 6200.

The obtained macromonomer was subjected to solution radical copolymerization with an equal amount of methyl methacrylate, and comparing the GPC charts before and after polymerization, disappearance of the macromonomer peak was confirmed, indicating that the macromonomer was a high-purity macromonomer. Indicated. The nuclear magnetic resonance absorption spectrum of this macromonomer is shown in FIG. 3, the infrared absorption spectrum is shown in FIG. 4, and the infrared absorption spectrum of the potassium salt of this macromonomer is shown in FIG.
Shown in the figure.

Example 3 In a glass flask equipped with a stirrer, a reflux condenser and a thermometer, 50 parts of the t-butyl methacrylate skeleton macromonomer obtained in Reference Example 1, 50 parts of methyl isobutyl ketone were added.
, 1.0 part of paratoluenesulfonic acid and 0.02 part of hydroquinone monomethyl ether, and reacted at 90 ° C for 9 hours. Four hours after the start of the reaction, 20 parts of ethanol was added, and two hours later, 30 parts of ethanol were added. After cooling, 4.0 parts of a commercially available anion exchange resin was added and stirred for 30 minutes.
After standing overnight, the reaction solution was filtered to remove the anion exchange resin, and then dried under vacuum to obtain a solid carboxyl group-containing macromonomer. This has an acid value of 6.425 (meq / g), and a methacrylic acid unit content of 55.3%. The average molecular weight in terms of polystyrene determined by gel permeation chromatography was Mn = 1400 and Mw = 1800.

The obtained macromonomer was subjected to solution radical copolymerization with an equal amount of methyl methacrylate, and a comparison of GPC charts before and after polymerization showed a decrease in the peak of the macromonomer, indicating that the macromonomer had a high carboxyl content. Indicated. The nuclear magnetic resonance absorption spectrum of this macromonomer is shown in FIG. 6, the infrared absorption spectrum is shown in FIG. 7, and the potassium salt of this macromonomer is shown in FIG.

Example 4 A glass flask equipped with a stirrer, a reflux condenser, and a thermometer was charged with 50 parts of the t-butyl methacrylate copolymer skeleton macromonomer obtained in Reference Example 2, 50 parts of methyl isobutyl ketone, and 1.0 parts of paratoluenesulfonic acid. And 0.02 part of hydroquinone monomethyl ether, and reacted at 90 ° C. for 9 hours. After cooling, 4.0 parts of a commercially available anion exchange resin was added and stirred for 30 minutes. After standing overnight, the reaction solution was filtered to remove the anion exchange resin, and then dried under vacuum to obtain a solid carboxyl group-containing macromonomer. The acid value of the product is 1.117 (meq / g), and the methacrylic acid unit content is 9.6%. The average molecular weight in terms of polystyrene by gel permeation chromatography is Mn = 26.
00, Mw = 4900.

The resulting macromonomer was subjected to solution radical copolymerization with an equal amount of methyl methacrylate, and the GPC charts before and after polymerization were compared.The disappearance of the macromonomer peak was confirmed, indicating that the macromonomer was a high-purity macromonomer. Was done.

(C) Effects of the Invention The carboxyl group-containing macromonomer in the present invention is copolymerized with another monomer to form a graft polymer, and is used for adhesives, pressure-sensitive adhesives, paints, coating materials, molding materials, elastomers, medical materials, electronic materials, and the like. It can be used as a polymer material. For example, a hot-melt pressure-sensitive adhesive or a thermoplastic elastomer can be obtained by expressing the physical crosslinking effect by utilizing the cohesive force of the carboxyl group-containing segment. In addition, as a reactive graft polymer, a crosslinking reaction or modification (for example, reaction with an epoxy compound, an amine, an alcohol, an isocyanate, an alkali compound, or the like) is performed, which can be used for high-performance and multifunctional polymer materials.

Furthermore, it can be used as a modifier, and can be used as a means for improving the performance and performance of general polymer materials.

Examples of the modifier used include surface modifiers for various polymer materials and interfacial modifiers (hydrophilizing agents for the surface, adhesion to the substrate,
Adhesion improver, etc.), Polymer blend compatibilizer (Nylon-based blend compatibilizer, etc.), Dispersant (Inorganic filler, Pigment dispersibility improver, etc.), Emulsifier (Reactive emulsifier, etc.), Biocompatibility Examples of the use include a material and a functional material such as a selectively permeable membrane material, which use a surfactant having a graft polymer or a multiphase structure.

Thus, the industrial value of the present invention is very large and greatly contributes to the industry.

[Brief description of the drawings]

1 is an infrared absorption spectrum of the t-butyl methacrylate skeleton macromonomer obtained in Reference Example 1, FIG. 2 is a nuclear magnetic resonance absorption spectrum thereof, and FIG. 3 is a nuclear magnetic resonance absorption of the macromonomer obtained in Example 2. FIG. 4 is an infrared absorption spectrum of the macromonomer, FIG. 5 is an infrared absorption spectrum of the potassium salt of the macromonomer, FIG. 6 is a nuclear magnetic resonance absorption spectrum of the macromonomer obtained in Example 2, FIG.
FIG. 8 shows the infrared absorption spectrum of the macromonomer, and FIG. 8 shows the infrared absorption spectrum of the potassium salt of the macromonomer. The symbol x in the nuclear magnetic resonance absorption spectrum diagram indicates that the absorption is due to impurities.

Claims (1)

(57) [Claims] 1. A linear polymer comprising a radically polymerizable vinyl monomer unit having a tertiary alkyl ester group and another radically polymerizable vinyl monomer unit,
By maintaining a macromonomer having a vinyl polymerizable functional group only at one end thereof at room temperature to 150 ° C. in the presence of an acid catalyst, the tertiary alkyl ester group is converted to an alkene and a carboxyl group based on the tertiary alkyl. A method for producing a carboxyl group-containing macromonomer, characterized by decomposing the macromonomer.