JP2002534499A - Emulsion polymerization using a compound that acts as both a surfactant and a polymerization initiator - Google Patents

Abstract

(57) [Summary] [Problem] A compound that functions as both a surfactant and a radical polymerization initiator. Useful in emulsion polymerization of block copolymers and graft copolymers. SOLUTION: A novel compound represented by a chemical formula [Formula 1]: (R ₁ is a hydrophilic group and P is a hydrophobic group, or R ₁ is a hydrophobic group and P is a hydrophilic group, n is an integer of 1 to 20, X is an oxygen atom or a sulfur atom, and Y is This compound (substituted nitrogen or oxygen atom) has a hydrophilic group and a hydrophobic group separated by a group containing a carbon-sulfur bond which can be separated into two radicals for initiating radical polymerization by homolysis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to polymerization in heterogeneous media, and more particularly to water-in-oil radical polymerization in which polymerization is initiated photochemically.

[0002]

[Prior art]

Emulsion polymerization is known, described in many references, and is used industrially in the synthesis of numerous polymers. Generally, when performing a radical emulsion polymerization, it is necessary to introduce a surfactant and a polymerization initiator into a reaction medium. The surfactant has a hydrophilic group and another hydrophobic group, and due to this amphiphilicity, the surfactant is located at the water / monomer interface to ensure the stability of the emulsion. The polymerization initiator is generally hydrophilic and soluble in the aqueous phase. It may be necessary to add other compounds to the reaction medium, such as a transfer agent and a terminator, to control the rate of the polymerization reaction and the average molecular weight of the resulting polymer.

[0003] Therefore, emulsion polymerization requires the use of multiple compounds, making the actual operation difficult and a costly process. Therefore, it is important to simplify the process by reducing the number of additives. However, hitherto, it has been virtually impossible to obtain a block copolymer by emulsion polymerization with a simple operation. Block copolymers are generally anionic polymerizations and are made by a rather expensive process.

[0004]

[Problems to be solved by the invention]

The present applicant has found that the above two problems can be solved at the same time by using a single compound having the above amphiphilic property and having a functional group generating two free radicals under irradiation with ultraviolet light. Was. These free radicals initiate radical polymerization and also act as transfer agents and / or terminators. Hereinafter, the compound of the present invention is referred to as “sur-iniferter”.

Another object of the present invention is a novel compound which is a surfactant, a radical polymerization initiator, and which is a transfer agent and / or a terminator. Still another object of the present invention is an emulsion polymerization method using a super iniferter which decomposes under irradiation of ultraviolet rays. This method is useful for the synthesis of photochemically initiated polymers and block copolymers.

[0006]

[Means to solve the problem]

 The super iniferter of the present invention corresponds to the general formula represented by the following formula:

[0007]

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(Here, R ₁ is a hydrophilic group and P is a hydrophobic group, or R ₁ is a hydrophobic group and P is a hydrophilic group.) One of R ₁ and P is as follows (1) to (3) ): (1) an ionic compound such as an alkali metal phenylsulfonate, (2) a nonionic compound having a terminal of a primary, secondary or tertiary amine, (3) a polymer compound such as a polyoxyalkylene unit, For example, selected from the group 1 (hydrophilic) consisting of polyoxyethylene and / or compounds containing carboxylic carboxylic acid functionalities, such as styrene / maleic anhydride copolymers, ethylene / (meth) acrylic acid copolymers and their ionomers. And the other is selected from Group 2 (hydrophobic) containing C1-C30 alkyl, aryl, and C5-C30 alkylaryl groups.

[0009] In general, hydrophobic means insoluble or incompatible with water. In the present invention, the hydrophobicity can be ranked. That is, in the present invention, the hydrophobicity is
It is defined by the solubility parameter (delta) as described in "Polymer properties" (DW Van Krevelen, 1990, 3rd edition, page 220). This parameter allows classification into different groups according to their affinity for water. In the present invention, groups having a "Delta" of 26 or less are hydrophobic. For example, (delta) R ₁ is 26
If so, (Delta) P is 26 or less, and vice versa.

[0010] n is an integer of 1 to 20, X is an oxygen atom or a sulfur atom, and Y is a nitrogen or oxygen atom. Depending on the choice of X and Y, different combinations are obtained. Preferred compounds of the present invention are selected from the following (1) to (3): (1) thiuram represented by the formula

[0011]

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(2) Xanthates represented by Chemical Formula 8

[0013]

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(3) Carbamoyl represented by the following formula:

[0015]

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[0016] _{(wherein, R 2, R 3, R} 4, R 5 and R ₆ are selected from the group 1 or group 2 in accordance with the desired hydrophilicity or hydrophobicity to be imparted to P) R ₁ The presence of and P ensures that the super-iniferter is amphiphilic and can act as a surfactant. In the present invention, a group represented by the following formula:

[0017]

[Formula 10]

The property of being cleaved into two free radicals under light irradiation gives the properties of a polymerization initiator, a terminator and / or a transfer agent. If a super iniferter is used in the emulsion polymerization, the super iniferter will first be water /
It is located at the interface of the organic phase and guarantees the stability of the emulsion. Next, under light irradiation, the superiniferter is cleaved to generate the following groups 3 and 4:

Base 3

[Formula 11]

Base 4

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In the presence of a radically polymerizable monomer (A), a radical centered on carbon (
The group 3) initiates the polymerization and the sulfur-centered radical (group 4) acts as a transfer agent and / or terminator, producing in-situ macroradicals according to the following reaction formula:

Decomposition

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Initiation and growth

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Movement

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[0025]

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Note the following two points. That is, first, the polymer produced by the action of group 1 includes a hydrophilic group R _1, dispersed in a continuous aqueous phase, remain stable. Secondly, the carbon-sulfur bonds formed in situ by the transfer and / or termination reactions are reversible under the action of ultraviolet radiation, which is advantageous for the production of graft block copolymers. In fact, after the polymerization of the first monomer, the second monomer (B) can be added to carry out the polymerization by reversibility of carbon-sulfur. This produces the above block copolymer of the formula:

[0027]

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Furthermore, if the super-iniferter initially comprises a polymer, ie R ₁ or
When P is selected from the polymer compounds of Group 1, a monomer A is polymerized according to the above reaction formula to obtain a graft copolymer in which the main chain is the polymer and the graft chain is a homopolymer of the monomer A. It should be noted that By polymerizing the second monomer B on such a copolymer, a graft copolymer having a graft chain composed of a block polymer composed of a poly unit (A) and a poly unit (B) can be obtained.

As described above, it can be understood that polymers having various structures can be obtained by emulsion polymerization using the super iniferter of the present invention. The reaction can be performed at ambient temperature or under heating. A method for manufacturing a super iniferter is described in Example 1. This method is for reference only and the invention is not limited to this embodiment.

Another object of the present invention is a radical emulsion polymerization method using the above super iniferter. A first embodiment of the invention comprises the following (a) and (b): (a) using at least one superiniferter corresponding to 0.1 to 40% by weight of the total weight of the monomers to be polymerized, Preparing an emulsion of at least one radically polymerizable monomer A in an aqueous phase in an amount of 0.5 to 70% by weight of the total weight of the emulsion, and (b) irradiating the emulsion with ultraviolet rays to initiate polymerization by the radicals formed. .

In the second embodiment of the present invention, after completely or partially polymerizing the monomer A, the second monomer B is introduced into the reaction medium, and the emulsion is irradiated with light to polymerize the second monomer B. The first method described above is particularly useful for the synthesis of homopolymers or random copolymers. In the second variant, a block copolymer AB is formed. One skilled in the art can determine the A / B ratio to obtain the desired copolymer depending on the operating conditions. Hereinafter, examples of the present invention will be described, but the present invention is not limited to the following examples.

[0032]

EXAMPLE 1 Super Iniferter : Preparation of 4- Diethylthiocarbamoylsulfaonylmethylbenzoic acid (DTBA) 0.1 mol of 4- (bromomethyl) benzoic acid and 0.1 mol of N, N-dithiocarbamic acid sodium salt And 500 ml of methanol are introduced into a glass reactor equipped with a cooling device and a magnetic stirrer, and stirred at 70 ° C. for 24 hours. The resulting mixture is then cooled to 4C. The final solution is evaporated at reduced pressure at ambient temperature. The crude reaction is washed with water, filtered and dried at ambient temperature. The yield is 98%.

Elemental analysis C ₁₃ H ₁₇ O ₂ S ₂ N: Calculated: C (55.09) H (6.05) O (11.29) S (22.63) N (4.94) Experimental: C (54.98) H (6.46) O (11.30) S (22.64) N (4.61) RMN1H (12.8; 1H; s), (7.9; 2H; d), (7.5; 2H; d), (4.7; 2H; s), (3.7-4.0; 4H ; Q
), (1.2; 6H; s)

Example 2 Emulsion polymerization of methyl methacrylate (MMA) in the presence of DBTA 150 ml of water, monomer and DBTA are introduced into a trichromatic glass reactor equipped with a cooling device under a nitrogen atmosphere. The pH is then adjusted with a 1N sodium hydroxide solution. The mixture is magnetically stirred at a rate of 600 revolutions / minute. The reactor is placed 15 cm away from the UV lamp (Philips HPK 125, 125 W, 640 cd / cm ² ) at ambient temperature. The experimental results are shown in [Table 1].

[0035]

[Table 1]

(Note) (1), (2): Number average molecular weight (Mn) and polymolecularity (IP). Measured by steric exclusion chromatography (SEC) using standard PMMA. A sample taken from the crude reaction product is first precipitated in methanol, dried and dissolved in 0.1% by weight, based on the solvent, of tetrahydrofuran (THF). (3): f is the functionality of the carboxyl group generated from DBTA in the final polymer. This f is determined by titrating the final polymer (precipitated in methanol and then dissolved in THF) using a potassium methoxide solution as an indicator colored with thymol blue. The particle size of the final latex is 40-200 nm and the latex obtained is stable during storage.

Example 3 Emulsion polymerization of styrene from pre-synthesized latex PMMA to obtain block copolymer PMMA-b-PS CS can be photochemically bonded and the PMMA latex has a functionality close to a carboxyl group unit, ie, a carbamate. If you have a group or iniferter,
This functional PMMA latex is equivalent to a macroinitiator. The block copolymer can be synthesized by emulsion polymerization. The procedure for this synthesis is as follows. First, MMA is polymerized in the presence of DTBA by the above method. After 24 hours of polymerization, a predetermined amount of styrene is added to the latex. The whole is then exposed to UV light as in the case of MMA polymerization. The test results are shown in [Table 2].

[0038]

[Table 2] (Composition is expressed in mass%)

For characterization of the crude reaction product (proportion of homopolymer PS and PMMA), a dissolution / precipitation cycle with cyclohexene and acetonitrile is performed. PMMA homopolymer is soluble in acetonitrile and PS homopolymer is soluble in cyclohexene.

Example 4 Production of Polymer Super Iniferter The production of the polymer super iniferter is carried out in the following two steps. a) Production of a super iniferter having an alcohol group at the hydrophilic end (a) 0.1 mol of N- (2-hydroxyethyl) piperazine, 0.1 mol of carbon disulfide and 250 m
l of dichloromethane are introduced into a 500 ml reactor and kept at 5 ° C. for 6 hours. The yellow precipitate formed is filtered at 40 ° C. under reduced pressure. It is then placed in a 1000 ml reactor containing 600 ml of methanol and 4 g of sodium hydroxide and stirred at 40 ° C. for 2 hours. Next, 100 ml of a methanol solution in which 0.1 mol of benzyl bromide is dissolved is introduced, and stirring is continued at 60 ° C. for 8 hours. The obtained product is dried under reduced pressure at 40 ° C. for 10 hours.

B) Preparation of high molecular super iniferter (b) 50 g of poly (ethylene-acrylic acid) and 5 g of super iniferter prepared in (a) are premixed together with 50 g of acetone, and the mixture is heated to 60 ° C. Maintain for 24 hours. The mixture is then stirred at 140 ° C. for 40 minutes at 32 revolutions / minute. Unreacted super iniferter (a) is extracted with acetone. 40 g of the reaction product and 4 g of sodium hydroxide are introduced into a 1000 ml reactor containing 500 g of water and stirred at 60 ° C. for 24 hours. The product obtained by dispersing in water (ultra iniferter (b)) is filtered and then
Let dry for 4 hours.

Example 5 Synthesis of Grafted Poly (Ethylene Acrylic Acid) Copolymer Grafted with Polymethyl Methacrylate 25 g of superiniferter (b) and 520 g of water are introduced into a 1000 ml reactor. 1-
Adjust the pH to 10 using N NaOH solution. The medium is purged with nitrogen and kept at 80 ° C for 4 hours 45
Stir at 0 rpm. Then, 50 g of methyl methacrylate are added. The polymerization is continued as in Example 2. The resulting product is filtered and dried at 60 ° C. for 24 hours. The conversion of methyl methacrylate is 55.5%. The degree of grafting measured after extraction of methyl homopolymethacrylate is 50.7%.

──────────────────────────────────────────────────続 き Continuation of front page (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE ), OA (BF, BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, GM, KE, LS, MW, SD, SL, SZ, TZ, UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, CA, CH, CN, CR, CU, CZ, DE, DK, DM, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID , IL, IN, IS, JP, KE, KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, NO, NZ, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TR, TT, TZ, UA, UG, US, UZ, VN, YU, ZA, ZW (72 ) Inventor Lacroix-Demaz, Patrick France 34090 Montpellier Avny de la Justice de Cas Terno 201 Pattiman d'Ophine (72) Inventor Kwak, Juho Republic of Korea Gangnam-Gonnon-Hyun-Don 218 F-term (reference) 4H006 AA01 AA03 AB40 AB68 TN50 TN60 4J011 KA03 KA04

Claims (11)

[Claims] 1. A compound represented by the general formula of [Chem. 1]: (Where R ₁ is a hydrophilic group and P is a hydrophobic group, or R ₁ is a hydrophobic group and P is a hydrophilic group, n is an integer of 1 to 20, X is an oxygen atom or a sulfur atom And Y is a substituted nitrogen or oxygen atom) 2. _One of R ₁ and P is the following (1) to (3): (1) an ionic compound such as an alkali metal phenylsulfonate, (2) a primary, secondary or tertiary amine. (3) polymeric compounds, such as polyoxyalkylene units, such as polyoxyethylene, and / or compounds containing carboxylic carboxylic acid functionality, such as styrene / maleic anhydride copolymers, ethylene / ( 2. A method according to claim 1, wherein said group is selected from the group consisting of (meth) acrylic acid copolymers and their ionomers, and the other group is selected from the group consisting of C1-C30 alkyl groups, aryl groups and C5-C30 alkylaryl groups. The compound according to the above. 3. The compound according to claim 2, wherein R ₁ is selected from Group 1 and P is selected from Group 2. 4. A group represented by the following chemical formula 2: Is selected from the following (1) to (3): (1) thiuram represented by the following formula (3): (2) Xanthates represented by [Chemical Formula 4] (3) Carbamoyl represented by [Chemical Formula 5] (Where R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are selected from group 1 or group 2 depending on the desired hydrophilicity or hydrophobicity imparted to P) 5. The compound according to claim 1, wherein R ₁ is sodium benzenesulfonate. 6. The compound according to claim 1, which is 4-diethylthiocarbamoylsulfaonylmethylbenzoic acid. 7. The compound according to claim 1, wherein R ₁ is selected from the group 1 polymer compounds. 8. A process for preparing a polymer by emulsion polymerization comprising the following steps (a) and (b): (a) at least one monomer A having 0.5 to 70% by weight of the total weight of the emulsion;
Into an emulsion using 0.1 to 40% of the compound according to any one of claims 1 to 6, and (b) irradiating the compound with ultraviolet rays at a temperature of -50 to 200 ° C, preferably 0 to 100 ° C. Is homolytically cleaved to initiate polymerization. 9. The method for producing a polymer according to claim 8, wherein the monomer A is selected from the group consisting of monomers capable of radical emulsion polymerization, such as vinyl monomers, (meth) acrylic monomers and derivatives thereof. 10. A polymer unit obtained by emulsion polymerization comprising the following steps (a) to (c):
A method for producing AB: (a) producing at least one monomer A by the method of claim 9; (b) adding a monomer B selected from Group 5 but different from A; The polymerization of monomer B is initiated by homolytic cleavage of the polymer formed by the polymerization of A. 11. A method for producing a graft polymer by emulsion polymerization comprising the following steps (a) and (b): (a) using 0.1 to 40% of the compound according to claim 7 to 0.5% of the total weight of the emulsion; ~
Preparing an emulsion of at least one monomer A having 70% by weight, and (b) irradiating with ultraviolet light at a temperature of -50 to 200 ° C, preferably 0 to 100 ° C, to homolytically cleave the compound to initiate polymerization. .