JP4337594B2 - Process for producing polycarboxylic acid macromonomer composition - Google Patents

Description

The present invention relates to a method for producing a macromonomer composed of a vinyl polymer having a carboxyl group and having an ethylenically unsaturated bond at a terminal in an aqueous medium.

Patent Document 1 proposes a method for producing a macromonomer having a carboxyl group by once synthesizing a macromonomer having an ester structure having a t-butoxy group as an alcohol residue and then decomposing the ester. Yes. However, there is a problem that a by-product such as isobutylene produced together with a carboxyl group in the decomposition of the ester has to be treated, and a disadvantage that much time is required for the decomposition process.
Patent Document 2 proposes a method of using a cobalt complex as a chain transfer agent in radical polymerization when producing a polymer skeleton. In this method, there is a problem that industrialization is difficult because the cobalt complex is highly toxic and the coloring is remarkable. Patent Document 2 does not disclose polymerization in an aqueous medium, and naturally does not disclose controlling the pH of the reaction solution.
Patent Document 3 proposes a method in which when an acrylic acid is radically polymerized at a high temperature of 220 ° C. or higher, an unsaturated bond is introduced into the polymer terminal. However, Patent Document 3 does not disclose controlling the pH of the reaction solution, and the polymer obtained by the method specifically disclosed in Patent Document 3 undergoes a Michael addition reaction or a decarboxylation reaction. Since it is easy, the acid concentration may be lowered, and it may be remarkably colored.
Patent Document 4 proposes a method of reacting a macromonomer having a hydroxyl group with carboxylic anhydride to introduce a carbosyl group into the macromonomer skeleton. However, this method has an economical problem because it requires an additional reaction step of carboxylic anhydride after the synthesis of the macromonomer. Moreover, this method has a limit in obtaining a high acid value.

Patent Document 5 proposes a method of performing radical polymerization of acrylic acid at 180 to 270 ° C. in the presence of a monoalkoxypolyalkylene glycol, but does not describe the presence of a macromonomer. Patent Document 5 does not disclose controlling the pH of the reaction solution, and the polymer obtained by the method specifically disclosed in Patent Document 5 has a very high terminal unsaturated group introduction rate. Even if it is small and contains a macromonomer, it is only low in purity.
Patent Document 6 proposes a method for producing an acrylic acid polymer in which an acrylic acid is polymerized in an aqueous solution at a pH of 3.5 or less and a temperature of 20 to 90 ° C. using a continuous stirred tank type process. However, the presence of macromonomers is not described. In the polymer obtained by the method disclosed in Patent Document 6, an unsaturated group is hardly introduced at the terminal, and even if a macromonomer is contained, the polymer is only low in purity.
Patent Document 7 proposes a method for producing an acrylic acid polymer in which pH is adjusted to a range of 6 to 9 and acrylic acid is polymerized in an aqueous solution at a temperature of 95 to 100 ° C. However, Patent Document 7 does not suggest the existence of a terminal unsaturated bond, and does not show the concept of use as a macromonomer. The polymer obtained by the method disclosed in Patent Document 7 has a very small introduction rate of terminal unsaturated groups, and even if a macromonomer is contained, the polymer is only low in purity.
Patent Document 8 proposes a method for producing an acrylic acid polymer in which acrylic acid is polymerized in an aqueous solution at a temperature of 130 to 240 ° C. However, Patent Document 8 does not suggest the existence of a terminal unsaturated bond, and does not disclose the concept of use as a macromonomer. Further, Patent Document 8 does not disclose controlling the pH of the reaction solution, and the method specifically disclosed in Patent Document 8, that is, a polymer obtained by using a large amount of a polymerization initiator, The introduction rate of terminal unsaturated groups is extremely small, and even if a macromonomer is contained, the purity is only low. Furthermore, since the Michael addition reaction and the decarboxylation reaction are likely to occur, the acid concentration may be lowered, and the product may be remarkably colored.
Patent Document 9, Patent Document 10, and Patent Document 11 disclose a method for controlling pH in order to smoothly copolymerize an ethylenically unsaturated dicarboxylic acid such as maleic acid with an ethylenically unsaturated monocarboxylic acid such as acrylic acid. Is disclosed. However, these known documents do not suggest the existence of terminal unsaturated bonds, nor do they suggest use as a macromonomer. In addition, the technology specifically disclosed in the examples has a polymerization temperature of 100 to 120 ° C., and the resulting polymer has a very low introduction rate of terminal unsaturated groups, even if a macromonomer is contained. It is only low purity.

JP-A-1-268709 Japanese Patent Laid-Open No. 9-176256 JP-A-8-3256 Japanese Patent Laid-Open No. 11-181021 JP 2003-40924 A JP 2003-2909 A JP-A-5-86125 JP-A-6-41206 JP 59-66407 A JP 59-64613 A JP-A-8-193101

The above known documents are organized.
Patent Documents 1 to 4 disclose macromonomers made of a vinyl polymer having a carboxyl group and having ethylenic unsaturation at the terminal.
The macromonomers described in Patent Documents 1 and 4 are significantly different in productivity from the macromonomers obtained by the present invention and have poor productivity. The structure of the macromonomer is also different from the macromonomer obtained by the present invention.
The macromonomer described in Patent Document 2 is greatly different from the macromonomer obtained by the present invention in the production method. Also, the macromonomer is different from the macromonomer obtained by the present invention in that it contains impurities and is easily colored.
The method for producing a macromonomer described in Patent Document 3 discloses the method for producing a macromonomer of the present invention as a superordinate concept. However, the polymer obtained by the specifically disclosed method is different from the present invention in that the polymer may have a reduced acid concentration and may be significantly colored.

  Patent Documents 5 to 11 disclose a method for producing a vinyl polymer having a carboxyl group, but do not describe any macromonomer composed of a vinyl polymer having ethylenic unsaturation at the terminal. The pH of the reaction solution and the reaction temperature are variously defined according to the purpose of each invention. However, the polymer obtained by the specifically disclosed method has a very small introduction rate of terminal unsaturated groups, and is substantially The present invention is different from the present invention in that it does not contain a macromonomer or has a low purity even if a macromonomer is contained.

The first object of the present invention is that the decrease in the acid concentration due to the Michael addition reaction or the decarboxylation reaction is small, the coloration is small, and the content of the macromonomer composed of a vinyl polymer having a carboxyl group is large. It is to provide a method for producing a macromonomer composition with high productivity (low cost) having a high content of polyunsaturation. The second object of the present invention is to copolymerize a macromonomer composed of a vinyl polymer having a carboxyl group contained in the macromonomer composition and an ethylenically unsaturated monomer, thereby graft copolymer or block copolymer. It is providing the method of manufacturing efficiently.

In order to solve the above problems, the method for producing a polycarboxylic acid macromonomer composition of the invention according to claim 1 comprises 20 to 100% by mass of ethylenically unsaturated monocarboxylic acid monomer (a-1), ethylene A monomer mixture consisting of 0 to 30% by mass of the unsaturated dicarboxylic acid monomer (a-2) and 0 to 80% by mass of the other ethylenically unsaturated monomer (a-3) in an aqueous medium In the pH range of 3.8 to 12 and the temperature range of 130 to 240 ° C., 0 to 3 mol% of a radical polymerization initiator is added and polymerized based on all monomers.
The manufacturing method of the polycarboxylic acid macromonomer composition of the invention described in claim 2 uses a continuous stirred tank reactor, and the ethylenically unsaturated monocarboxylic acid monomer (a-1) 20 to 100 mass. %, A monomer mixture consisting of 0 to 30% by mass of ethylenically unsaturated dicarboxylic acid monomer (a-2) and 0 to 80% by mass of other ethylenically unsaturated monomer (a-3), In a medium with a pH of 3.8 to 12 and a temperature of 110 to 240 ° C., 0 to 3 mol% of a radical polymerization initiator is added based on the total monomers, and the average residence time is 5 to 120 minutes. It is characterized by polymerizing.
The method for producing a polycarboxylic acid macromonomer composition according to claim 3 is the method according to claim 1 or 2, wherein the ratio of ethylenically unsaturated dicarboxylic acid monomer (a-2) is 0 to 0. It is characterized by being 10% by mass.
The method for producing a polycarboxylic acid macromonomer composition of the invention according to claim 4 is the invention according to claim 1 or 2, wherein the addition amount of the radical polymerization initiator is 0 to 1 mol% based on the total monomers. It is characterized by being.
The method for producing the polycarboxylic acid macromonomer composition of the invention according to claim 5 is the method according to claim 1 or 2, wherein the above-mentioned unit is used in the range of pH 4.5 to 11 and temperature of 130 ° C to 215 ° C. The polymer mixture is polymerized.

The method for producing a copolymer according to claim 6 comprises 20 to 100% by mass of ethylenically unsaturated monocarboxylic acid monomer (a-1), ethylenically unsaturated dicarboxylic acid monomer (a-2) 0. A monomer mixture consisting of ˜30% by mass and other ethylenically unsaturated monomers (a-3) 0-80% by mass in an aqueous medium at a pH of 3.8-12 and a temperature of 110-240 ° C. In the range, a radical reaction of a polycarboxylic acid macromonomer composition obtained by adding 0 to 3 mol% of a radical polymerization initiator based on the total monomers and polymerizing it with the ethylenically unsaturated monomer (b) It is characterized by making it.

Little decrease in acid concentration due to Michael addition reaction or decarboxylation reaction, little coloration, high content of macromonomer composed of vinyl polymer having carboxyl group, that is, high content of terminal ethylenic unsaturation, The macromonomer composition could be produced with high productivity (at low cost).
A graft copolymer or a block copolymer could be efficiently produced by copolymerizing a macromonomer composed of a vinyl polymer having a carboxyl group and a vinyl monomer contained in the macromonomer composition.
The macromonomer, that is, the polycarboxylic acid macromonomer and the graft polymer and block polymer having a polycarboxylic acid polymer unit are useful for various applications. For example, organic pigment dispersants, inorganic pigment dispersants, thickeners, associative thickeners, flocculants, paper agents such as paper sizing agents and paper strength enhancers, detergent builders, polymeric emulsifiers, reactive polymers It can be used for emulsifiers, coatings, ink binders, varnishes, compatibilizers and the like.

In this specification, acrylic and methacryl are collectively referred to as (meth) acryl.
The ethylenically unsaturated monocarboxylic acid monomer (a-1) is a monomer having an ethylenically unsaturated bond and one carboxyl group in the molecule. Specific examples include methacrylic acid and acrylic acid. These can use 1 type, or 2 or more types.

  The ethylenically unsaturated dicarboxylic acid monomer (a-2) is a monomer having an ethylenically unsaturated bond and two carboxyl groups in the molecule. Specific examples include maleic acid, itaconic acid, fumaric acid and the like. These can use 1 type, or 2 or more types.

  The other ethylenically unsaturated monomer (a-3) is ethylenic other than the ethylenically unsaturated monocarboxylic acid monomer (a-1) and the ethylenically unsaturated dicarboxylic acid monomer (a-2). It is an unsaturated monomer. Specific examples include (meth) acrylamide, (meth) acrylic dialkylamide, (meth) acrylic acid polyalkylene glycol ester, (meth) acrylic acid alkoxyalkyl ester, (meth) acrylic acid hydroxyalkyl ester, styrene sulfonic acid, 2 Water-soluble or highly hydrophilic ethylenically unsaturated monomers such as -acrylamido-2-methylpropane-sulfonic acid, vinylpyrrolidone, (meth) acrylonitrile, (meth) acrylic acid dialkylaminoalkyl esters and quaternary salts thereof It is mentioned as preferable. However, hydrophobic ethylenically unsaturated monomers can be used as long as they do not inhibit polymerization in an aqueous medium. Specific examples of the hydrophobic ethylenically unsaturated monomer include (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms (the alkyl group may be linear or branched), (meth) acrylic acid Glycidyl ester, (meth) acrylic acid benzyl ester, (meth) acrylic acid phenoxyalkyl ester, (meth) acrylic acid cyclohexyl ester, (meth) acrylic acid isobornyl ester, (meth) acrylic acid alkoxysilylalkyl ester, vinyl ester , Vinyl ethers, (meth) allyl ethers, styrene, α-methylstyrene and the like. These can be used alone or in combination of two or more.

The method for producing the polycarboxylic acid macromonomer of the present invention comprises 20 to 100% by mass of ethylenically unsaturated monocarboxylic acid monomer (a-1), ethylenically unsaturated dicarboxylic acid monomer (a-2) 0 to 0. It is obtained by radical polymerization of a monomer mixture composed of 30% by mass and other ethylenically unsaturated monomers (a-3) 0 to 80% by mass. The sum of (a-1), (a-2) and (a-3) is 100% by mass.
When the ratio of (a-1) is smaller than 20% by mass, the acid value becomes too small. Moreover, the terminal ethylenically unsaturated bond introduction rate is lowered. When (a-2) is more than 30% by mass, β-cleavage is unlikely to occur, and the introduction rate of terminal ethylenically unsaturated bonds decreases.
A preferred ratio of the ethylenically unsaturated monocarboxylic acid monomer (a-1), the ethylenically unsaturated dicarboxylic acid monomer (a-2) and the other ethylenically unsaturated monomer (a-3) is: They are 50-100 mass%, 0-20 mass%, and 0-50 mass%, respectively, and a more preferable ratio is 70-100 mass%, 0-10 mass%, and 0-30 mass%.

  The radical polymerization of the monomer mixture takes place in an aqueous medium. The aqueous medium is water itself or a mixed solution of water and an organic solvent miscible with water. The aqueous medium preferably contains 50% by mass or more of water, more preferably contains 70% by mass or more, and further preferably contains 90% by mass or more. Examples of organic solvents miscible with water include, but are not limited to, acetone, methanol, ethanol, isopropyl alcohol, tetrahydrofuran, ethylene glycol, glycerin, dioxane, acetonitrile and the like. Acetone and methanol having a low chain transfer ability are preferred. Solvents with high chain transfer ability such as ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol and isopropyl alcohol are used because a chain transfer agent is introduced at the polymer end and the introduction rate of ethylenically unsaturated bonds at the end is lowered. Is preferably avoided.

  The monomer mixture preferably has a concentration of 5 to 65% by mass based on 100% by mass of the total amount of the monomer mixture and the aqueous medium. A more preferable concentration is 15 to 55% by mass, and a further preferable concentration is 25 to 45% by mass. If the concentration is too low, productivity may be poor. If the concentration is too high, it is difficult to control the molecular weight, which may lead to gelation. In addition, as the polymer produced increases in molecular weight, the viscosity may increase and a uniform reaction may not be possible.

The polymerization of the monomer mixture is performed at a temperature of 110 to 240 ° C.
If the polymerization temperature is too low, the frequency of β-cleavage occurring in the main chain of the produced polymer becomes low, and the ratio of ethylenically unsaturated groups introduced to the polymer ends becomes small. On the other hand, if the polymerization temperature is too low, the polymer tends to have a branched structure, resulting in an increase in viscosity due to a high molecular weight or gelation. When the polymerization is carried out using a continuous stirred tank reactor, the above problem is alleviated, so the lower limit of the polymerization temperature is 110 ° C., preferably 120 ° C., more preferably 130 ° C. When the polymerization is carried out without using a continuous stirred tank reactor, the lower limit of the polymerization temperature is preferably 130 ° C, more preferably 140 ° C, and even more preferably 150 ° C.
The upper limit of the polymerization temperature is preferably 215 ° C, more preferably 205 ° C. If the polymerization temperature is too high, a decarboxylation reaction that is a decomposition reaction of the carboxyl group occurs and the acid value becomes small. In addition, the coloring becomes remarkable.

The polymerization of the monomer mixture is performed in the range of pH 3.8-12. A preferred range is pH 4.5-11, and a more preferred range is pH 5.5-10. When the pH before polymerization and after polymerization are different, the pH before polymerization is targeted.
If the pH is less than 3.8, the proportion of ethylenically unsaturated groups introduced at the ends of the polymer is small. On the other hand, if the pH is less than 3.8, the polymer tends to have a branch, so that the viscosity increases due to high molecular weight or gelation occurs. Further, the Michael addition product may increase and the acid concentration may decrease, and the coloring may be significant.
If the pH is greater than 12, the equipment may be easily corroded.
The neutralizing agent used for neutralizing the carboxylic acid is not particularly limited, and examples thereof include sodium hydroxide, potassium hydroxide, ammonia, and organic amine.

It was particularly important that the polymerization temperature and pH were controlled within the above ranges, and as a result, it was found that the ratio of introducing ethylenically unsaturated groups at the ends of the polymer was increased. The reason is considered to be that, under the above conditions, a reaction in which a hydrogen atom bonded to a tertiary carbon atom in the main chain of the produced polymer is extracted as a hydrogen radical occurs frequently. That is, a reaction in which a hydrogen atom bonded to an α-position carbon atom derived from an ethylenically unsaturated monocarboxylic acid (a-1) unit or another ethylenically unsaturated monomer (a-3) unit is extracted as a hydrogen radical. This is considered to occur at a high frequency, and the frequency of the β-cleavage reaction that follows the hydrogen radical abstraction reaction is also increased.
By controlling the polymerization temperature and pH within the above ranges, the molecular weight is low and a large amount of ethylenically unsaturated groups accompanying β-cleavage are introduced at the end without using a chain transfer agent or a large amount of radical polymerization initiator. Thus, a polymer, that is, a macromonomer can be obtained efficiently.
By controlling the polymerization temperature and pH within the above ranges, the decrease in the acid concentration due to the Michael addition reaction and the decarboxylation reaction is small, the coloring is small, and the content ratio of the macromonomer composed of a vinyl polymer having a carboxyl group is reduced. A macromonomer composition having a large content of terminal ethylenic unsaturation, ie, a large content of terminal ethylenic unsaturation, can be produced with high productivity (at a low cost).

  In radical polymerization of the monomer mixture, a radical polymerization initiator capable of initiating radical polymerization in an aqueous medium can be used. Examples thereof include t-butyl hydroperoxide, hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, and a water-soluble azo initiator. T-butyl hydroperoxide, sodium persulfate, potassium persulfate and hydrogen peroxide are preferred. The use ratio of the radical polymerization initiator is 0 to 3 mol%, preferably 0.001 to 2 mol%, more preferably 0.01 to 1 mol%, based on all monomers. When the amount of the radical polymerization initiator used is too large, a large amount of initiator fragments are introduced at the ends of the polymer, so that the introduction rate of terminal unsaturated groups of the macromonomer becomes low. The reason why the lower limit of the amount of the radical polymerization initiator used is 0 mol% is that radical polymerization may occur without using a radical polymerization initiator.

In carrying out radical polymerization of the monomer mixture, a chain transfer agent can be used. However, the chain transfer agent should be used in an amount of 0 to 10 mol% based on the total monomers. Preferably it is 0-5 mol%, More preferably, it is 0-1 mol%, Most preferably, it is not using it substantially. If the amount of the chain transfer agent used is too large, the proportion of the polymer in which a group derived from the chain transfer agent is introduced at the terminal increases, and the yield of the polymer having an ethylenically unsaturated group at the terminal, that is, the macromonomer yield is increased. Get smaller.
The chain transfer agent here has a chain transfer constant (C = growth reaction rate constant kp / chain transfer reaction rate constant kf) defined by Polymer Handbook 4th Edition or the like of 10 ⁻⁴ or more. Specifically, isopropyl alcohol, sec-butyl alcohol, ethylene glycol, propylene glycol, carbitol, polyalkylene glycol, organic solvents such as cumene, mercaptan compounds such as mercaptoethanol and mercaptopropionic acid, sulfites, bisulfites, Examples thereof include hypophosphite, hypophosphorous acid, ammonium formate, hydroxyammonium sulfate, formaldehyde and the like.

  The radical polymerization of the monomer mixture includes known polymerization methods such as batch polymerization, semi-batch polymerization, polymerization using a tubular reactor, polymerization using a continuous stirred tank reactor (CSTR), and multistage polymerization combining these. Can be implemented. A preferred polymerization method is a polymerization method using a continuous stirred tank reactor (CSTR). For example, a polymerization method using a continuous stirred tank reactor (CSTR) disclosed in JP-T-57-502171, JP-A-59-6207, JP-A-60-215007, etc. may be used as a reference. . The polymerization method using CSTR can narrow the molecular weight distribution, composition distribution, and residence time distribution of the polymer produced compared to other polymerization methods, so that a more uniform polycarboxylic acid macromonomer can be obtained. .

  The reaction time (residence time) for radical polymerization of the monomer mixture is not particularly limited, but is preferably 5 to 300 minutes, more preferably 5 to 120 minutes, and further preferably 5 to 60 minutes. If it is longer than 300 minutes, the terminal unsaturated bond produced is consumed by newly generated initiator radicals, and the introduction rate of the terminal unsaturated group of the macromonomer may be lowered. Moreover, productivity is also bad and coloring and heat deterioration may occur. If the reaction time is less than 5 minutes, the monomer may not sufficiently react, and production problems such as difficulty in removing heat of polymerization may occur.

The polycarboxylic acid macromonomer composition obtained by the present invention preferably has a weight average molecular weight of 300 to 120,000. When the weight average molecular weight is less than 300, the function as a polycarboxylic acid may not be exhibited. That is, a macromonomer composition or a graft polymer composition or block polymer composition having a macromonomer unit as a constituent unit is a dispersant, a thickener, a flocculant, a paper sizing agent, a paper strength enhancer, or a detergent builder. When used as a polymer emulsifier, a coating agent, a compatibilizing agent, etc., the performance may be insufficient.
When the weight average molecular weight is greater than 120,000, the macromonomer composition tends to have a low terminal unsaturated group introduction rate. When the macromonomer composition and the ethylenically unsaturated monomer (b) are radically reacted, The coalescence may not be obtained in good yield.
The preferred weight average molecular weight of the polycarboxylic acid macromonomer composition is 500 to 80000, more preferably 1000 to 50000, and still more preferably 1500 to 20000.

  The polycarboxylic acid macromonomer composition contains a polycarboxylic acid macromonomer having a structure represented by the following formula (1).

In the formula (1), M means a monomer unit, n is a natural number representing the degree of polymerization, X is -COOR, -CONR2, -OR, -OCOR, -OCOOR, -NCOOR, a halogen atom,- CN or an optionally substituted phenyl group or aryl group. R represents an alkyl group, a hydroxyalkyl group, an alkoxyalkyl group, an alkyl group which may have other substituents, a phenyl group, a benzyl group, a polyalkylene glycol group, a dialkylaminoalkyl group, a trialkoxysilylalkyl group or hydrogen. Is an atom.
In the case where X is a carboxyl group, those which are neutralized with an alkali and are salts exemplified by -COONa, -COOK, -COONH _{4 and the} like are also included.

The introduction rate of terminal ethylenically unsaturated bonds in the polycarboxylic acid macromonomer composition (hereinafter also simply referred to as terminal unsaturated bond introduction rate) is defined by the following formula.
Terminal unsaturated bond introduction rate (f) = terminal ethylenically unsaturated bond molar concentration / polymer molar concentration In other words, terminal unsaturated bond introduction rate (f) is the number of ethylenically unsaturated bonds at one end of a polymer molecule. Average value. The terminal unsaturated bond introduction rate in this invention is 0.5-2.5. Preferably it is 0.7-1.5, More preferably, it is 0.8-1.2. If it is less than 0.5, the copolymer cannot be obtained in good yield when the macromonomer composition and the ethylenically unsaturated monomer (b) are subjected to radical reaction. When the ratio is larger than 2.5, problems such as gelation and an increase in molecular weight distribution occur when the macromonomer composition and the ethylenically unsaturated monomer (b) undergo a radical reaction.

It is presumed that the terminal ethylenically unsaturated bond introduction mechanism in the production process of the polycarboxylic acid macromonomer composition of the present invention is as follows. The monomer used for the production of the polycarboxylic acid macromonomer composition will be described as CH ₂ = CHX.

  The polymer undergoes hydrogen radical abstraction and becomes a polymer having a radical on the α-carbon (carbon to which X is bonded) (a polymer having a structure represented by the formula (2)).

  When the radical of the polymer having the structure represented by the formula (2) and the monomer undergo an addition reaction, a branched polymer (polymer having the structure represented by the formula (3)) is generated.

  When a polymer having the structure represented by the formula (2) undergoes a β-cleavage reaction (a reaction in which the bond at the β-position carbon and the γ-position carbon is broken), a polymer having an ethylenically unsaturated bond at the terminal (formula (4 ), That is, a macromonomer and a polymer radical (polymer having the structure shown in Formula (5)).

The reaction for producing a polymer having the structure represented by the formula (3) and the reaction for producing a polymer having the structure represented by the formula (4), that is, a macromonomer, are competitive reactions.
The present invention has found that by controlling the polymerization conditions as described above, the production ratio of the polymer having the structure represented by the formula (3) can be reduced, and the macromonomer can be obtained efficiently.

  Since the macromonomer of the present invention is presumed to be produced by the above-described mechanism, when the β-cleavage frequency is sufficiently high, the terminal unsaturated bond introduction rate (f) is theoretically 1.0 on average. That is, the average number of terminal unsaturated bonds per polymer is one. However, probabilistically, the number of terminal unsaturated bonds has a distribution, and there are some macromonomer components in which unsaturated bonds exist at both ends. Therefore, problems such as gelation may occur depending on the production conditions of the graft polymer. Although the reason is not well understood, it has been experimentally observed that the terminal unsaturated bond introduction rate (f) exceeds 1.0.

  Since the polycarboxylic acid macromonomer composition of the present invention has a high content of macromonomer having an unsaturated bond at the terminal, it is allowed to undergo a radical reaction with the ethylenically unsaturated monomer (b) to efficiently produce a copolymer. Can be manufactured.

  Production of the above copolymer, that is, radical reaction between the polycarboxylic acid macromonomer composition and the ethylenically unsaturated monomer (b) includes emulsion polymerization, water dispersion polymerization, aqueous solution polymerization, solution polymerization, bulk polymerization, sheet polymerization, etc. It can be carried out by a known radical polymerization method. Since the polycarboxylic acid macromonomer is produced in an aqueous solution, polymerization in an aqueous medium is preferred.

  The copolymer obtained by the radical reaction of the polycarboxylic acid macromonomer composition and the ethylenically unsaturated monomer (b) has a block copolymer when the graft copolymer is a main component depending on the reaction conditions. When the main component is used, the graft copolymer and the block copolymer may coexist.

  When it is intended to obtain a copolymer containing a graft copolymer as a main component, it is necessary to carefully consider the macromonomer formation mechanism. That is, it is considered that the state in which the growth radical is added to the macromonomer becomes a tertiary radical and has the same structure as the polymer having the structure represented by the formula (2). Under conditions suitable for the production of macromonomer and pH, beta-cleavage takes precedence over branching (grafting) reaction, so that the reaction to the graft polymer hardly proceeds. For these reasons, the preferable temperature for the graft polymer production conditions is 50 to 110 ° C, more preferably 60 to 100 ° C, and the most preferable temperature is 70 to 95 ° C. Moreover, the range of 3.5-12 is preferable, pH4.5-11 is more preferable, and pH5.5-10 is still more preferable. If the pH is lower than 3.5, gelation is likely to occur and it may be difficult to control the polymerization reaction. If the pH is higher than 12, problems such as decomposition and coloring may occur.

The ethylenically unsaturated monomer (b) is not particularly limited as long as it has radical polymerizability.
When it is intended to obtain a copolymer having a graft copolymer as a main component, the ethylenically unsaturated monomer (b) is in the α-position based on the total amount of the ethylenically unsaturated monomer (b). It is preferable to contain 30 mol% or more of hydrogen-containing monomers. Those containing 50 mol% or more of a monomer having hydrogen at the α-position are more preferred, and those containing 70 mol% or more are more preferred.
When the ratio of the monomer having hydrogen at the α-position is less than 30 mol%, that is, for example, when the ratio of the monomer having a methyl group at the α-position exceeds 70 mol%, the graft copolymerization rate is significantly lowered. The reason is guessed as follows. When a monomer having a methyl group at the α-position is added to the macromonomer, a tertiary radical having a methyl group in an adjacent unit is generated. Under the influence of the methyl group, the tertiary radical rapidly causes β-cleavage and a branching reaction proceeds. do not do. Therefore, it is considered that the graft copolymerization reaction is remarkably slow when the ratio of the monomer having a methyl group at the α-position is large.

  Examples of the monomer having hydrogen at the α-position include acrylic acid, acrylamide, acrylic dialkylamide, acrylic acid polyalkylene glycol ester, acrylic acid alkoxyalkyl ester, acrylic acid hydroxyalkyl ester, styrenesulfonic acid, and 2-acrylamide-2. -Methylpropane-sulfonic acid, vinylpyrrolidone, dialkylaminoalkyl acrylate and its quaternary salts, alkyl acrylate (alkyl group may be linear or branched), glycidyl acrylate, benzyl acrylate, acrylic Acid phenoxyalkyl ester, cyclohexyl acrylate ester, isobornyl acrylate ester, alkoxysilylalkyl acrylate vinyl ester vinyl ester, trifluoroethyl acrylate Over DOO, perfluoroalkylethyl acrylates, vinyl ethers, vinyl esters, allyl ethers, acrylonitrile, styrene and the like. A water-soluble or highly hydrophilic vinyl monomer is particularly preferred.

Examples of monomers having a group other than hydrogen at the α-position include methacrylic acid, methacrylamide, methacryl dialkylamide, methacrylic acid polyalkylene glycol ester, methacrylic acid alkoxyalkyl ester, and methacrylic acid hydroxyalkyl ester. , Methacrylic acid dialkylaminoalkyl esters and quaternary salts thereof, itaconic acid, methacrylic acid alkyl esters (the alkyl group may be linear or branched), methacrylic acid glycidyl ester, methacrylic acid benzyl ester, methacrylic acid Phenoxyalkyl ester, methacrylic acid cyclohexyl ester, methacrylic acid isobornyl ester, methacrylic acid alkoxysilylalkyl ester vinyl esters, trifluoroethyl methacrylate Perfluoroalkylethyl methacrylate, methacrylonitrile, etc. α- methyl styrene. A water-soluble or highly hydrophilic vinyl monomer is particularly preferred.

Example 1 (Production of polymer 1)
36 g of sodium acrylate (AA-Na), 64 g of water, and 0.2 g of a 69% aqueous solution of t-butyl hydroperoxide (TBHP) were mixed. The mixture was pH 8.0 at 20 ° C. 3 g of the mixed solution was charged into a SUS316 reaction tube having an outer diameter of 10 mm and sealed. The reaction tube was completely immersed in an oil bath previously maintained at 200 ° C., taken out after 30 minutes, and rapidly cooled with water. The aqueous solution obtained from the reaction tube was light yellow and had a pH of 11.0. Next, ion exchange was performed with an ion exchange resin to remove sodium salts, and vacuum drying was performed to obtain a polymer 1. From the weight, the conversion was found to be about 90% or more. The molecular weight of the dried polyacrylic acid was measured with aqueous GPC, and the molecular weight was calculated with a calibration curve made of standard polyacrylic acid. The weight average molecular weight (Mw) was 3400, the number average molecular weight (Mn) was 1300, and the molecular weight. The distribution Mw / Mn was 2.6. Further, ¹ H-NMR measurement was performed, and peaks derived from terminal ethylenically unsaturated bonds were observed at 5.6 PPM and 6.1 PPM. However, no ester-derived peak associated with the Michael addition reaction of 4.2 PPM was observed. The terminal unsaturated bond introduction ratio (f) was calculated from the peak intensity of the terminal unsaturated bond, the peak intensity ratio derived from protons in the main chain of 1.2 PPM to 2.8 PPM, and the number average molecular weight. f was 1.5.

Examples 2-5 and Comparative Examples 1-2 (Production of Polymers 2-5 and Comparative Polymers 1-2)
In the same manner as in Example 1, polymers 2 to 5 and comparative polymers 1 to 2 were produced by changing the pH. All the polymerization rates were 90% or more. When the pH was 3.5 or less, the molecular weight distribution was widened, the amount of terminal unsaturated bonds was lower than that exceeding pH 3.5, and coloring was intense. The results are shown in Table 1.

Examples 6 to 10 and Comparative Examples 3 to 4 (Production of Polymers 6 to 10 and Comparative Polymers 3 to 4)
In the same manner as in Example 1, polymers 6 to 10 and comparative polymers 3 to 4 were produced by changing the pH at 150 ° C. Polymers 6 to 10 had a polymerization rate of 90% or more. Gelation occurred at pH 3.5 or lower. The results are shown in Table 2.

Comparative Examples 5-9 (Production of Comparative Polymers 5-9)
Comparative Examples 6 to 9 were produced by changing the pH in the same manner as in Example 1 except that sodium persulfate was used as the initiator and the reaction temperature was changed to 100 ° C. All gelled. The results are shown in Table 3.

Example 11 (Production of polymer 11)
18 g of sodium acrylate (AA-Na), 18 g of sodium methacrylate (MAA-Na), 64 g of water, and 0.2 g of a 69% aqueous solution of t-butyl hydroperoxide (TBHP) were mixed. The mixture had a pH of 7.8 at 20 ° C. 3 g of the mixed solution was charged into a SUS316 reaction tube having an outer diameter of 10 mm. The reaction tube was completely immersed in an oil bath previously maintained at 200 ° C., taken out after 30 minutes, and rapidly cooled with water. The aqueous solution obtained from the reaction tube was light yellow and had a pH of 10.7. Analysis was performed in the same manner as in Example 1, and Mw 2500, Mn 1000, Mw / Mn = 2.5, and f was 1.1.

Example 12 (Production of polymer 12)
The oil jacket temperature of a 1 liter pressurized stirred tank reactor equipped with an oil jacket was kept at 200 ° C. Next, a tertiary butyl hydroperoxide (hereinafter referred to as TBHP) as a polymerization initiator was added to a monomer mixture consisting of 84 parts by weight of sodium acrylate (AA-Na), 16 parts by weight of acrylic acid (AA), and 169 parts by weight of water. 0.5 part by weight was mixed and charged into the raw material tank. The raw material tank is continuously supplied to the reactor at a constant supply rate (48 g / min, residence time: 12 minutes), and the polymer is continuously fed from the reactor outlet so that the weight of the mixed liquid in the reactor is constant 580 g. Extracted. The pH of the extracted reaction solution was 6.5. At that time, the internal temperature of the reactor was maintained at a desired 200 ° C.
After the start of the monomer mixture supply, it was judged that an almost equilibrium state was reached 36 minutes after the temperature inside the reactor was stabilized, and then about 2.9 kg of a sodium polyacrylate aqueous solution was recovered. The color of the liquid was light yellow. The residual AA was analyzed by liquid chromatography and found to be 2.1 wt%. From the result, it was found that the polymerization rate was 94%.
In the same manner as in Example 1, after the ion exchange treatment, the molecular weight and the terminal unsaturated bond introduction rate (f) were measured. Mw was 7900, Mn was 3100, and molecular weight distribution Mw / Mn was 2.5. The terminal unsaturated bond introduction rate (f) was 1.1.

Example 13 (Production of Graft Copolymer 1)
In a reaction vessel equipped with a stirrer, reflux condenser, thermometer, and nitrogen introduction tube, 100 parts by weight of an aqueous solution of sodium polycarboxylate macromonomer (polymer 12) produced in Example 12 and 100 parts by weight of water were charged, and a nitrogen atmosphere Under 90 ° C. Separately prepared monomer solution comprising 36 parts by weight of sodium acrylate (AA-Na), 6.9 parts by weight of acrylic acid (AA), 0.8 part by weight of sodium persulfate (NPS), and 20 parts by weight of water. It was dripped continuously over time. After completion of the dropwise addition, 0.1 part by weight of sodium persulfate (NPS) and 4 parts by weight of water were added and the reaction was continued for 1 hour. During this period, the reaction temperature was maintained at 90 ° C.
The molecular weight of the obtained copolymer was Mw52000, Mn8200, Mw / Mn = 6.3 from GPC measurement. The polymerization rate determined from the remaining AA-Na was 92%. The reaction rate of the macromonomer determined by NMR was 95%, and it was confirmed that most of the macromonomer reacted.

Various physical properties in Examples and Comparative Examples were measured by the following methods.
(1) Weight average molecular weight (Mw), number average molecular weight (Mn), molecular weight distribution (Mw / Mn) were measured by gel permeation chromatograph (GPC), water + phosphate buffer was used as eluent, acrylic acid Measurement was made in terms of polyacrylic acid using a standard polymer.
(2) The pH was measured using a pH meter. The pH after polymerization in Examples 1 to 11 was measured by diluting 5 times.
(3) Terminal unsaturated bond introduction rate (f)
The aqueous polymer solution obtained in the examples was subjected to ion exchange with an ion exchange resin in order to remove the influence of residual monomers, and dried in a vacuum dryer and used for measurement. Measurement was performed using heavy water as a solvent by ¹ H-NMR, and peak strengths derived from terminal unsaturated bonds in 5.6 PPM and 6.1 PPM and protons in the main chain of 1.2 PPM to 2.8 PPM (methylene and methine). From the peak intensity ratio derived from the proton and the Mn of GPC.
f = (peak intensity of main chain / 3) / (end unsaturated hydrogen peak intensity / 2) × 72 / Mn
(4) Michael addition production
Measurement was performed using heavy water as a solvent in ¹ H-NMR, and the peak intensity ratio derived from the ester of 4.2 PPM and the peak intensity ratio derived from the protons in the main chain of 1.2 PPM to 2.8 PPM as shown in the following formula: Calculated.
Michael addition amount = (ester peak intensity / 2) / (peak intensity of main chain / 3) × 100
(5) Coloring was evaluated visually.
(6) Residual acrylic acid was quantified by reverse phase liquid chromatography using an ODS column. The polymerization rate was calculated from the amount of residual acrylic acid.

As is clear from the results shown in Tables 1 and 2, the molecular weight and molecular weight distribution increased or gelled as the pH decreased even at the same temperature and the same initiator amount. This indicates that the β-cleavage occurs more frequently as the pH is closer to the neutral region, and supports a higher terminal unsaturated bond introduction rate. However, the polymerization results at 100 ° C. shown in Table 3 indicate that gelation occurs even when the pH is close to the neutral region, and that the branching reaction takes precedence over β-cleavage at 100 ° C.
When the pH below 3.5 in Tables 1 and 2 is observed, gelation occurs at 150 ° C., indicating that the branching reaction takes precedence, and gelation is avoided at 200 ° C., but there is a Mw / Mn of 23 or more and branching reaction. Is happening frequently. The amount of coloring and Michael adduct is also high at pH 3.5 or less. From these, it was shown that the production of the polycarboxylic acid macromonomer is optimal in the range of pH 3.8 to pH 12 and the temperature range of 110 ° C. to 240 ° C.

  Although Example 12 showed the example which superposed | polymerized using the continuous stirred tank type | mold reactor (CSTR), in Examples 1-11, although pH changed with progress of superposition | polymerization, an Example In the method of 12, the polymerization can be continuously carried out while maintaining a substantially constant pH of 6.5, and a high terminal unsaturated bond introduction rate and a narrow molecular weight distribution can be achieved. It has been shown that the process using CSTR is a suitable process for the production of polycarboxylic acid macromonomers. For example, the method using CSTR can suitably produce a polycarboxylic acid macromonomer in a wider temperature range than the method not using CSTR.

In Example 13, an example in which the polycarboxylic acid macromonomer was copolymerized with acrylic acid was shown. A high graft polymerization rate was shown, and it was found that this condition was suitable for graft copolymerization.

  The present invention economically produces a polycarboxylic acid macromonomer having a high terminal unsaturated bond introduction rate, a high acid value, and little coloration, and a copolymer having a polycarboxylic acid unit by radical polymerization which is industrially easy In particular, the present invention provides a method for producing a graft polymer having a polycarboxylic acid unit as a branch. The graft polymer having a polycarboxylic acid macromonomer and a polycarboxylic acid as a branch in the present invention has high function and quality and is useful for various applications. Examples of applications include organic or inorganic pigment dispersants, thickeners, associative thickeners, flocculants, paper agents such as paper sizing agents and paper strength enhancers, detergent builders, polymeric emulsifiers, reactions For example, a functional polymer emulsifier, a coating, an ink binder, a varnish, and a compatibilizer.

Claims (6)

Ethylenically unsaturated monocarboxylic acid monomer (a-1) 20 to 100% by mass, ethylenically unsaturated dicarboxylic acid monomer (a-2) 0 to 30% by mass and other ethylenically unsaturated monomers (A-3) A monomer mixture composed of 0 to 80% by mass in an aqueous medium at a pH of 3.8 to 12 and a temperature of 130 to 240 ° C. A method for producing a polycarboxylic acid macromonomer composition which is polymerized by adding a radical polymerization initiator. Using a continuous stirred tank reactor, ethylenically unsaturated monocarboxylic acid monomer (a-1) 20 to 100% by mass, ethylenically unsaturated dicarboxylic acid monomer (a-2) 0 to 30% by mass % And other ethylenically unsaturated monomers (a-3) in a range of pH 3.8 to 12, temperature 110 to 240 ° C. in an aqueous medium, A method for producing a polycarboxylic acid macromonomer composition in which 0 to 3 mol% of a radical polymerization initiator is added based on the total monomers and polymerized under conditions of an average residence time of 5 to 120 minutes. The manufacturing method of the polycarboxylic acid macromonomer composition of Claim 1 or 2 whose ratio of an ethylenically unsaturated dicarboxylic acid monomer (a-2) is 0-10 mass%. The method for producing a polycarboxylic acid macromonomer composition according to claim 1 or 2, wherein the addition amount of the radical polymerization initiator is 0 to 1 mol% based on the total monomers. The method for producing a polycarboxylic acid macromonomer composition according to claim 1 or 2, wherein the monomer mixture is polymerized in a pH range of 4.5 to 11 and a temperature range of 130C to 215C. Ethylenically unsaturated monocarboxylic acid monomer (a-1) 20 to 100% by mass, ethylenically unsaturated dicarboxylic acid monomer (a-2) 0 to 30% by mass and other ethylenically unsaturated monomers (A-3) A monomer mixture composed of 0 to 80% by mass in an aqueous medium at a pH of 3.8 to 12 and at a temperature of 110 to 240 ° C. A method for producing a copolymer in which a polycarboxylic acid macromonomer composition obtained by polymerizing by adding a radical polymerization initiator is radically reacted with an ethylenically unsaturated monomer (b).