JP4688697B2 - Dithioester derivative, chain transfer agent, and method for producing radical polymerizable polymer using the same - Google Patents

Description

  The present invention relates to a novel dithioester derivative and a chain transfer agent, and a radical polymerizable polymer using the same.

  As living radical polymerization having a narrow molecular weight distribution and capable of block copolymerization, a system using an initiator and a reversible addition-cleavage chain transfer agent (hereinafter referred to as RAFT agent) (hereinafter referred to as RAFT polymerization). Known (Patent Document 1). RAFT polymerization is a polymerization method in which a radical polymerizable monomer is polymerized with a polymerization initiator in the presence of a RAFT agent. A dithioester compound is generally known as a RAFT agent for RAFT polymerization.

  Examples of these RAFT agents include compounds represented by the following general formula (4). However, since these are compounds that emit a strong odor, they are restricted in handling during synthesis or use, and may cause health damage to the user and deterioration of the working environment. Furthermore, since the polymer obtained by using this also has an odor, the problem of odor occurs during the processing and use of the resin, which may cause health and environmental problems.

Z ₁ group represented by the above formula (4) is phenyl group, benzyl group, naphthyl group, alkyl group, thioalkyl group, and R group is optionally substituted alkyl group, optionally substituted saturated or Unsaturated aromatic carbocycle or heterocycle.

Special Table 2000-515181

  In view of the above-described circumstances, the present invention provides a compound having a dithioester group with less malodor, a dithioester derivative used as a RAFT agent that gives a polymer having a narrow molecular weight distribution when used in RAFT polymerization, a chain transfer agent, and the same An object of the present invention is to provide a method for producing a radically polymerizable polymer using

  As a result of earnest research on chain transfer agents that suppress bad odor and give a polymer having a narrow molecular weight distribution in the polymerization of radical polymerizable polymers, dithioester compounds containing fluorine represented by the following general formula (1) are obtained. The present invention was completed by discovering that it is suitable as a chain transfer agent for radical polymerization.

  This invention exists in the dithioester derivative characterized by being represented by following General formula (1).

In general formula (1), Z is a group represented by the following formula (2) or (3), R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group, R ₃ is a hydrogen atom, Halogen atom, aryl group, alkyl group, hydroxyl group (—OH), alkoxy group (—OR ′), carbonyl group (—COOR ′) and carboxylate, cyano group (—CN), nitro group (—NO ₂ ) , Carbamoyl group (—CONR ′), sulfonyl group (—SO ₃ H) and sulfonate, primary, secondary, tertiary amino group (—NH ₂ , —NH alkyl, —N dialkyl), heterocyclic group Any of them.

  Moreover, the other aspect of this invention exists in the RAFT agent used for RAFT polymerization characterized by consisting of the said dithioester derivative.

  Furthermore, another aspect of the present invention provides a method for producing a radical polymerizable polymer, characterized in that a radical polymerizable polymer is obtained by RAFT polymerization of a radical polymerizable monomer using the dithioester derivative as a RAFT agent. is there.

  Since the dithioester derivative of the present invention has the above-described configuration, it is a compound that can suppress odor and suppress the generation of unpleasant odor of the polymer. Further, it was found that when used as a RAFT agent in RAFT polymerization, the molecular weight adjustment and low polydispersity effects equivalent to or higher than those of the conventional RAFT agent are exhibited.

  The dithioester derivative of the present invention is a compound represented by the above formula (1). The dithioester derivative represented by the above formula (1) is a compound having extremely little sulfur odor which is an unpleasant odor compared to the compound represented by the above formula (4).

  As will be described later, the dithioester derivative is excellent in molecular weight adjustment and low polydispersity when used as a RAFT agent in RAFT polymerization.

In the general formula (1), R ₁ is a hydrogen atom or an alkyl group, preferably a hydrogen atom or a lower alkyl group, and most preferably a hydrogen atom or carbon number 1 from the viewpoint of synthesis and availability of reagents.

R ₂ is a hydrogen atom or an alkyl group, preferably a hydrogen atom or a lower alkyl group, and most preferably hydrogen and one carbon atom from the viewpoint of synthesis and availability of reagents.

R ₃ represents a hydrogen atom, a halogen atom, an aryl group, an alkyl group, a hydroxyl group (—OH), an alkoxy group (—OR ′), a carbonyl group (—COOR ′) and a carboxylate, a cyano group (—CN), nitro Groups (—NO ₂ ), carbamoyl groups (—CONR ′), sulfonyl groups (—SO ₃ H) and sulfonates, primary, secondary and tertiary amino groups (—NH ₂ , —NH alkyl, —N Dialkyl), a heterocyclic group. In particular, R ₃ is preferably hydrogen in view of synthesis and availability of reagents.

  An example of the synthesis method of the dithioester derivative will be described. First, a magnesium bromide derivative is synthesized by a Grignard reaction of a bromo compound corresponding to the Z group in the above formula (1). A dithiocarbonate derivative is synthesized by adding carbon disulfide to the obtained magnesium bromide derivative and refluxing it. The obtained dithiocarbonate derivative is refluxed in an ethylene derivative and carbon tetrachloride to obtain the dithioester derivative.

  The dithioester derivative is a compound that can be suitably used as a RAFT agent for adjusting the molecular weight of a polymer and obtaining a low polydispersity polymer in RAFT polymerization of a radical polymerizable monomer.

  Moreover, when using the said dithioester derivative as a RAFT agent, there exists an effect of exhibiting the effect of molecular weight adjustment and low polydispersity equal to or higher than those of the conventional RAFT agent.

  Furthermore, the dithioester derivative has an effect that the odor problem of the RAFT agent itself is relatively less than that of the conventional RAFT agent.

  The radical polymerizable monomer used when RAFT polymerization is performed using the RAFT agent of the present invention is not particularly limited. For example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, 2, 4-dimethylstyrene, pn-butylstyrene, p-ter-xylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxy Styrenes (styrene monomers) such as styrene, p-phenylstyrene, p-chlorostyrene, p-acetoxystyrene, 3,4-dichlorostyrene; acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate , Isobutyl acrylate, propyl acrylate, n-octyl acrylate, acrylate Sil, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, ethyl methacrylate, propyl methacrylate, n-octyl methacrylate, dodecyl methacrylate Α-methyl fatty acid monocarboxylic acid esters such as lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, etc. Acrylic acid, methacrylic acid and derivatives thereof (acrylic monomers); organic acids such as maleic acid, crotonic acid, itaconic acid, fumaric acid, N-vinylformamide, N-vinyl Pyrrolidone, N- vinyl caprolactam and N- vinyl compounds such as N- vinyl pyridine. These may be used alone or in combination of two or more.

  When the dithioester derivative is used as a RAFT agent in RAFT polymerization, the amount of the RAFT agent blended with the radical polymerizable monomer is not particularly limited, but generally the molecular weight is increased in the conversion rate (blending rate) of the RAFT agent. It will increase with. The molecular weight Mn of the product can be calculated according to the following relation: Therefore, when the purpose is to control the molecular weight, the blending amount of the RAFT agent can be determined according to the desired molecular weight.

Mn = {[number of moles of monomer consumed] / [number of moles of RAFT agent]} × molecular weight of monomer + molecular weight of RAFT agent

  The polymerization method of the radical polymerizable monomer using the RAFT agent of the present invention is not particularly limited, and can be performed by a conventionally known method, for example, solution polymerization method, bulk polymerization method, emulsion polymerization method, suspension polymerization method. Etc.

  The polymerization initiator used for radical polymerization of the radically polymerizable monomer using the RAFT agent of the present invention is not particularly limited. For example, azo polymerization such as 2,2′-azobis (2,4-dimethylvaleronitrile) Initiators; peroxide polymerization initiators such as lauryl peroxide and benzoyl peroxide; persulfide polymerization initiators such as potassium persulfate, sodium persulfate, and ammonium persulfate. Moreover, not only a thermal initiator but also a redox initiator, a photopolymerization initiator, or an initiator by high energy radiation such as electron beam, X-ray, gamma ray, and the like can be mentioned.

  The blending amount of the polymerization initiator is not particularly limited, but in order to synthesize a polymer having a narrow molecular weight distribution, the total number of moles of the polymerization initiator may be less than 0.5 times the number of moles of the RAFT agent. preferable. The molecular weight distribution can be controlled by changing [number of moles of RAFT agent] / [number of moles of polymerization initiator]. By increasing this ratio, a narrower molecular weight distribution is obtained. A broader molecular weight distribution is obtained by reducing this ratio.

  In the radical polymerization of the radical polymerizable monomer, the polymerization temperature is usually in the range of -20 ° C to 200 ° C, preferably in the range of 40 ° C to 160 ° C.

  The radical polymerizable polymer obtained by the radical polymerization has a dispersity of 1.5 or less, which is mainly a ratio of the weight average molecular weight to the number average molecular weight. Therefore, the RAFT agent is excellent in low polydispersity effect. Moreover, the problem of the odor of the polymer obtained is also suppressed.

  Since the dithioester derivative of the present invention is a compound represented by the above general formula (1), it is a compound with extremely little sulfur odor which is an unpleasant odor.

  In addition, when the dithioester derivative represented by the above general formula (1) is used as the RAFT agent in the RAFT polymerization by the solution polymerization method, the bulk polymerization method or the emulsion polymerization method, the above-mentioned conventional RAFT agent is used. Compared to, it exhibits a molecular weight adjustment effect equal to or greater than that.

  Moreover, the polymer obtained by the manufacturing method of the radically polymerizable polymer which uses the dithioester derivative represented by the said General formula (1) as a RAFT agent is compared with the case where the conventionally used RAFT agent is used. The problem of the odor of the resin is suppressed.

(Test example)
The odors of the RAFT agent of the following example of the present invention, the conventional RAFT agent of the comparative example, and the polymer of the following example obtained using these RAFT agents were measured by the following method. The measurement was carried out by a scoring method using 10 panelists. Depending on the strength of the odor, “strong odor”, “slightly strong odor”, “normal odor”, “weak odor”, “no odor” are 5 points, 4 points, 3 points, 2 points, 1 point respectively. Evaluation was based on the average score.

The monomer used was purified to remove the polymerization inhibitor from commercially available monomers. As the polymerization solvent, propylene glycol monomethyl ether (hereinafter referred to as PGME) was used, and as the radical polymerization initiator, 2,2′-azobisisobutylnitrile (hereinafter referred to as AIBN) was used. Before polymerization, N ₂ bubbling is performed for 30 minutes for deaeration. For the polymerization, an NMR tube was used. A sample tube sealed with D ₂ O was placed inside. Benzyltrimethylsilane was added as an internal standard.

The molecular weight of the polymer was measured by gel permeation chromatography (hereinafter referred to as GPC method). Tetrahydrofuran (hereinafter THF) (flow rate 1.0 mL / min) was used as the eluent. The molecular weight was measured using polystyrene as a standard product. The terms Mn, Mw, Mw / Mn are used to indicate number average molecular weight, weight average molecular weight, and polydispersity, respectively. The theoretical molecular weight Mn _th was calculated according to the following formula.

Mn _th = {[number of moles of consumed monomer] / [number of moles of RAFT agent]} × molecular weight of monomer + molecular weight of RAFT agent

The number of moles of consumed monomer was determined from the peak area reduction amount of the vinyl group proton of the monomer by ¹ H-NMR spectroscopy.

  The monomer, RAFT agent and polymerization initiator were charged so that the molar ratio was [monomer] / [RAFT agent] / [AIBN] = 60/1 / 0.2.

Example 1
RAFT agent 1: Synthesis of 1-phenylethylpentafluorophenyl dithioacetate (Z = formula (2), R ₁ = CH ₃ , R ₂ = H, R ₃ = H))
Magnesium (1.8 g) was added in dry diethyl ether (50 mL). Here, pentafluorobenzyl bromide (18.2 g) was added dropwise at room temperature over 1 hour. Thereafter, the mixture was refluxed at 70 ° C. for 30 minutes. Carbon disulfide (5.7 g) was added dropwise thereto over 15 minutes, and then refluxed for 20 minutes. Thereafter, 80 mL of pure water was added, and the mixture was washed 3 times with dityl ether (total 300 mL). When diethyl ether was added a third time, 37% HCl (10 mL) was added to extract the product from the organic layer. The diethyl ether layer was concentrated to obtain pentafluorodithiocarbonate (2.2 g).

The pentafluorobenzyldithiocarbonate (2.2 g) obtained above and styrene (1.0 g) and carbon tetrachloride (20 mL) were refluxed for 45 hours with mixing. Recrystallization was performed with hexane to obtain RAFT agent 1 (1-phenylethylpentafluorophenyl dithioacetate) (0.5 g) as a yellow solid. The melting point was 51.8-53.0 ° C. and ¹ H-NMR was as follows.

¹ H-NMR (CDCl ₃ ) (ppm): δ 1.67 (d, 3H), δ 4.18 (s, 2H), δ 5.04 (q, 1H), δ 7.2-7.8 (m, 5H) ). ¹³ C-NMR (CDCl ₃ ) (ppm): δ21, δ47, δ50, δ126-150 (10C), δ227.

  Moreover, the result of having measured the odor of the obtained compound according to said method was 3.1 points.

(Production Example 1)
Synthesis of Polymer Using RAFT Agent 1 of Example 1 Acetoxystyrene (hereinafter AcSt) (3.0 g), 1-phenylethylpentafluorophenyl dithioacetate (112.8 mg), AIBN (10.28 mg), PGME 1 g from the (9.0 g) solution was placed in an NMR tube and heated at 70 ° C. for 8 hours. This solution was further dissolved in THF and measured by GPC method. As a result, Mn was 5200 and Mw / Mn was 1.11.

  Moreover, the result of having measured the odor of the obtained resin according to said method was 2.2 points.

(Example 2)
RAFT agent 2: Synthesis of 2-phenylpropylpentafluorophenyl dithioacetate (Z = formula (2), R ₁ = CH ₃ , R ₂ = CH ₃ , R ₃ = H)
Pentafluorobenzyl dithiocarbonate was obtained in the same manner as in Example 1.

Pentafluorodithiocarbonate (3.2 g), carbon tetrachloride (20 mL), and methylstyrene (1.5 g) were mixed and refluxed for 26.5 hours. Then, after distilling off the solvent carbon tetrachloride, purification was performed by column chromatography (hexane) to obtain 2-phenylpropylpentafluorophenyl dithioacetate (0.8 g) as a yellow solid. Melting point was 62.3-63.5 ° C. and ¹ H-NMR was as follows.

¹ H-NMR (CDCl ₃ ) (ppm); δ 2.03 (s, 6H), δ 4.20 (s, 2H), δ 7.2-7.6 (m, 5H). ¹³ C-NMR (CDCl ₃ ) (ppm); δ28, δ44, δ57, δ125-144 (10C), δ277.

  Moreover, the result of having measured the odor of the obtained compound according to said method was 3.1 points.

(Production Example 2)
Synthesis of polymer using RAFT agent 2 of Example 2 AcSt (3.0 g), 2-phenylpropylpentafluorophenyl dithioacetate (117.4 mg), AIBN (10.2 mg), PGME (9.0 g) 1 g from the solution was placed in an NMR tube and heated at 70 ° C. for 11 hours. When this solution was further dissolved in THF and measured by GPC method, Mn was 4800 and Mw / Mn was 1.08.

  Moreover, the result of having measured the odor of the obtained resin according to said method was 2.5 points.

(Example 3)
RAFT agent 3: Synthesis of pentafluorobenzyl dithiobenzoate (Z = formula (3), R ₁ = H, R ₂ = H, R ₃ = H)
Pentafluorophenylacetic acid (2.9 g), benzyl mercaptan (1.7 g), diphosphorus pentasulfide (3.1 g), and toluene (150 mL) were refluxed for 24 hours with mixing. After refluxing, the mixture was cooled in an ice bath and the precipitated solid was filtered. After evaporating the solvent of the filtrate, the residue was purified by column chromatography (hexane / chloroform = 30/1) (hexane / chloroform = 1/1) twice to obtain pentafluorobenzyl dithiobenzoate (0.4 g) as a red solid. Got in. Melting point was 43.2-44.0 ° C. and ¹ H-NMR was as follows.

¹ H-NMR (CDCl ₃ ) (ppm): δ 4.55 s (2H), δ 7.2-7.5 (5H). ¹³ C-NMR (CDCl ₃ ) (ppm): δ42, δ120-143 (12C), δ211.

  Moreover, the result of having measured the odor of the obtained compound according to said method was 3.8 points.

(Production Example 3)
Synthesis of polymer using RAFT agent 3 of Example 3 From a solution of AcSt (3.0 g), pentafluorobenzyl dithiobenzoate (114.5 mg), AIBN (10.3 mg), PGME (9.0 g), 1 g Was placed in an NMR tube and heated at 70 ° C. for 8 hours. When THF was added to this solution and measured by the GPC method, Mn was 2600 and Mw / Mn was 1.15.

  Moreover, the result of having measured the odor of the obtained resin by said method was 2.7 points.

(Comparative Example 1)
Conventional RAFT Agent: Synthesis of 2-Phenyldithiobenzoate The title compound was synthesized according to the procedure of US Pat.

  The result of measuring the odor of the obtained compound by the above method was 4.9 points.

(Production Comparative Example 1)
Synthesis of Polymer Using RAFT Agent of Comparative Example 1 1 g from a solution of AcSt (3.0 g), AIBN (10.2 mg), phenyldithiobenzoate (124.8 mg) and PGME (9.0 g) into an NMR tube And heated at 70 ° C. for 12 hours. When THF was added to this solution and measured by the GPC method, Mn was 3400 and Mw / Mn was 1.17.

  The odor of the obtained resin was measured according to the above method and found to be 4.8 points.

(Production Comparative Example 2)
Synthesis of polymer when no RAFT agent was used 1 g from a solution of AcSt (3.0 g), AIBN (10.1 mg), and PGME (9.0 g) was placed in an NMR tube and heated at 70 ° C. for 12 hours. When THF was added to this solution and measured by GPC method, Mn was 29400 and Mw / Mn was 1.71.

  From Table 1, it was found that the odor was suppressed in the RAFT agents obtained in Examples 1, 2, and 3 as compared with the RAFT agent used in Comparative Example 1. Moreover, it turned out that the polymer synthesize | combined using these is a polymer with a low odor similarly.

Furthermore, it is recognized that the molecular weight distribution of the polymer is lower than that of Comparative Example 2 in which the RAFT agent is not used, and low polydispersity equal to or higher than that of Comparative Example 1 in which the conventional RAFT agent is used. It was found that a polymer having

Claims (3)

A dithioester derivative represented by the following general formula (1):

In general formula (1), Z is a group represented by the following formula (2) or (3), R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group, R ₃ is a hydrogen atom, halogen atom, an aryl group, an alkyl group, a hydroxyl group, an alkoxy group, a carbonyl Moto及 beauty carboxylate, cyano group, a nitro group, a carbamoyl group, a sulfonyl Moto及 beauty sulfonates, primary, secondary, tertiary amino A group or a heterocyclic group.

A chain transfer agent used for reversible addition-fragmentation chain transfer polymerization, comprising the dithioester derivative according to claim 1. A method for producing a radical polymerizable polymer, comprising using the dithioester derivative of claim 1 as a chain transfer agent to obtain a radical polymerizable polymer by reversibly addition-cleaving chain transfer polymerization of a radical polymerizable monomer.