JP4411377B2 - Method for producing polymer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to polymer production how using supercritical carbon dioxide.
[0002]
[Prior art]
Conventional methods for producing polymers such as polymer fine powder include solution polymerization of unsaturated monomers in an organic solvent, removal of the organic solvent from the resulting polymer solution, drying, pulverization, etc. The process of doing is common. In this process, several steps are required to obtain a polymer. Further, when the polymer fine powder is produced by such a process, there is a disadvantage that the size of the obtained fine powder becomes non-uniform.
[0003]
As another method, JP-A-56-76447 discloses a method in which a water-insoluble unsaturated monomer is dispersed in water in the presence of a surfactant and subjected to emulsion polymerization. However, in such a method, since a large amount of water is used, a large amount of wastewater treatment is required, and the environmental load is large. In addition, when trying to produce a fine polymer powder by such a process, the fine particles are fused to each other when the obtained fine particles are isolated, resulting in large particles or lumps. Is difficult to get.
[0004]
In recent years, research on a reaction method using supercritical carbon dioxide as a solvent has been advanced as a reaction method with a low environmental load. Also in the field of polymer synthesis, synthesis of polymers using supercritical carbon dioxide as a solvent is being considered instead of the conventional production method using a large amount of an organic solvent. For example, JP-A-8-104830 discloses a technique for producing polymer fine particles for coating by dissolving a polymer material polymerized once in a supercritical phase and rapidly expanding the solution. JP-A-113652 discloses a method for producing a polymer fine particle for coating by dissolving a polymer solid once produced in a supercritical phase and rapidly expanding it.
[0005]
However, these disclosed techniques require a process of obtaining a polymer material by performing a polymerization reaction with a solvent other than the supercritical fluid prior to expansion in the supercritical phase, and thus the process is complicated and the amount of organic solvent It is difficult to achieve weight loss.
[0006]
As a technique for performing a polymerization reaction in a supercritical fluid, a method of reacting a monomer mixture of styrene-acrylonitrile in supercritical carbon dioxide in the presence of a radical polymerization initiator (JP-A-8-41135) A method of reacting a monomer mixture of styrene-vinyl acetate in supercritical carbon dioxide in the presence of a radical polymerization initiator (Japanese Patent Laid-Open No. 10-45838) is known.
[0007]
However, in these disclosed techniques, the former yield is 84% and the latter yield is 12 to 56%, and a process for removing unreacted monomers remaining in the system is necessary. is there. Furthermore, in these disclosed methods, since the polymer is produced in a molten state that is not dissolved in supercritical carbon dioxide, the polymer composition is obtained in a lump. Therefore, further steps such as pulverization are required to obtain the polymer fine powder.
[0008]
On the other hand, JP 9-503798 A discloses a dispersion polymerization reaction of a polymer in supercritical carbon dioxide using a surfactant having a fluorinated and siliconized site as a supercritical carbon dioxide soluble site. Is disclosed. However, the yield is as low as 20 to 75%, which is disadvantageous for polymer production on an industrial scale. Moreover, since the polymer product obtained by the method contains a fluoropolymer, it is hardly soluble in an organic solvent and lacks versatility. When such a polymer product is used as it is as a coating composition or the like, unevenness on the surface of the coating film due to the oil and water repellency of fluorine appears, making it difficult to use in such applications. Moreover, when it is going to remove a fluoropolymer from the polymer product obtained by the said method, it is necessary to use a large amount of organic solvents, and it becomes difficult to reduce an environmental load after all.
[0009]
[Problems to be solved by the invention]
A first object of the present invention is to provide a method for producing a polymer that can efficiently obtain a polymer having a low environmental load, a simple process, a high yield, and high versatility.
[0011]
[Means for Solving the Problems]
According to the present invention, it is possible to polymerize a polymerizable monomer in supercritical carbon dioxide in the presence of a non-polymerizable dispersant having 10 or more carbon atoms and having at least one carboxyl group in the molecule. A method for producing the characterized polymer is provided.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
In the method for producing a polymer of the present invention, a polymerizable monomer is polymerized in supercritical carbon dioxide.
[0014]
The supercritical carbon dioxide is obtained by heating and pressurizing carbon dioxide to the critical point (critical temperature 31 ° C. or critical pressure 73.5 kg / cm ² ) or higher, and is not liquefied even if it is further pressurized. This refers to carbon dioxide that has become a fluid in a state, and usually has gas and liquid properties.
[0015]
The supercritical carbon dioxide can be obtained by introducing a commercially available carbon dioxide gas contained in a cylinder or the like into a reaction vessel in which a polymerization reaction is performed, and setting a predetermined temperature and pressure. The carbon dioxide gas to be introduced preferably has a purity of 99.9% or higher.
[0016]
The supercritical carbon dioxide may be further mixed with another additive solvent. As the additive solvent, water, lower alcohols such as methanol and ethanol, acetonitrile and the like can be used. The additive solvent can be added in an amount of about 0.1 to 100 parts by weight with respect to 100 parts by weight of supercritical carbon dioxide, but it is preferable not to use the additive solvent from the viewpoint of preventing pollution and reducing the environmental load. .
[0017]
In the method for producing a polymer of the present invention, polymerization is carried out in the presence of a specific non-polymerizable dispersant.
[0018]
The non-polymerizable dispersant has at least one carboxyl group in the molecule and has 10 or more carbon atoms constituting the molecule.
[0019]
When the carbon number of the non-polymerizable dispersant is less than 10, the dispersibility in supercritical carbon dioxide is low, and the polymer and the monomer are not dispersed in supercritical carbon dioxide. Reactive monomer remains.
[0020]
Examples of the non-polymerizable dispersant include decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid, nonadecanoic acid, eicosanoic acid, docosanoic acid and the like. 40 linear or branched long-chain alkyl carboxylic acids, or aromatic carboxylic acids having 10 to 40 carbon atoms such as 1-naphthoic acid and 2-naphthoic acid, or a weight average molecular weight of 1,000 to 1,000,000 And a weight average molecular weight of 1,000 to 1,000,000, and a carboxylic acid ratio (ratio of monomer units having a carboxylic acid in the total amount of monomer units constituting the polymer) is 1 to 99. A mol% polycarboxylic acid copolymer may be mentioned. Preferably, a fatty acid having 14 or more carbon atoms can be used, and a long-chain alkyl carboxylic acid having 20 to 40 carbon atoms or a branched alkyl carboxylic acid having 20 to 40 carbon atoms is particularly preferable.
[0021]
The polymerizable monomer that is polymerized in the production method of the present invention is not particularly limited as long as it is a monomer that can be polymerized in supercritical carbon dioxide in the presence of the non-polymerizable dispersant. Those having at least one ethylenically unsaturated bond can be used. Specifically, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) ) (Meth) acrylic acid alkyl esters such as acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, hexadecyl (meth) acrylate; methacrylic acid, acrylic acid , Crotonic acid, itaconic acid, mesaconic acid, maleic acid, fumaric acid and other polymerizable carboxylic acids, their half esters and their diesters; ω-carboxy-polycaprolactone (n = 2) monoacrylate [Example For example, hydrocarbon chains such as Aronix M-5300 (trade name, manufactured by Toagosei Chemical Industry Co., Ltd.) or acrylic acid dimer [for example, Aronix M-5600 (trade name, manufactured by Toagosei Chemical Industry Co., Ltd.)]. A compound having an unsaturated bond at the terminal of hydroxyl group; a hydroxyl group-containing monomer such as hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and polyethylene glycol (meth) acrylate; styrene such as styrene and α-methylstyrene Examples thereof include vinyl monomers such as vinyl acetate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; p-vinyltoluene and acrylonitrile. Furthermore, fluorine-containing α, β-ethylenically unsaturated monomers such as 2,2,2-trifluoromethyl acrylate, 2,2,2-trifluoromethyl methacrylate and the like can be mentioned. These may be used alone or in combination of two or more. Among them, (meth) acrylic acid alkyl ester is particularly preferable.
[0022]
In the production method of the present invention, the polymerization mode of the polymerizable monomer composition is not particularly limited, and can be a known polymerization mode. For example, any of radical polymerization, anionic polymerization, and cationic polymerization may be used, and radical polymerization is particularly preferable.
[0023]
The radical polymerization can be performed using a polymerization initiator. The polymerization initiator is not particularly limited, and examples thereof include t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxyneodecanate, t-butyl peroxypivalate, methyl ethyl ketone peroxide, Organic peroxides such as acetylcyclohexylsulfonyl peroxide, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (isobutyronitrile) (hereinafter abbreviated as AIBN), Preferred examples include azo initiators such as 2,2′-azobis (2-methylbutyronitrile). AIBN is particularly preferable.
[0024]
These radical polymerization initiators may be used alone or in combination of two or more.
[0025]
The amount of radical polymerization initiator used can be appropriately determined from the molecular weight of the target polymer, and is not particularly limited, but is preferably 0.001 to 30 parts by weight with respect to 100 parts by weight of the polymerizable monomer. More preferably, it can be 0.1-10 weight part.
[0026]
Specifically, the polymerization is performed, for example, by using 5 to 1,500 parts by weight of carbon dioxide with respect to 100 parts by weight of the polymerizable monomer, and a pressure of 30 to 400 kg / cm ² , preferably 60 to It can be carried out batchwise at 360 kg / cm ^{2 and} at a temperature of 31 to 160 ° C., preferably 40 to 150 ° C. In particular, the reaction temperature when the polymerization is performed by radical polymerization is preferably 40 to 150 ° C, more preferably 50 to 100 ° C. A reaction temperature of 50 to 100 ° C. is particularly preferred because the radical polymerization initiator is easily decomposed by heat and the growth reaction is likely to proceed effectively.
[0027]
The polymerization time for carrying out the polymerization depends on the polymerization temperature and other conditions and cannot be fixed, but generally 2 to 48 hours are preferable.
[0028]
The polymerization can be carried out by adding 0.01 to 100 parts by weight, preferably 0.1 to 50 parts by weight of the non-polymerizable dispersant with respect to 100 parts by weight of the monomer. When the amount of the non-polymerizable dispersant added to 100 parts by weight of the monomer is less than 0.01 parts by weight, the dispersant has low dispersibility, and the polymer, polymer radical and monomer are not sufficiently dispersed in supercritical carbon dioxide. Therefore, the polymerization is not completed, and unreacted monomers remain in the polymer, which is not preferable. Moreover, when it exceeds 100 weight part, the intensity | strength of the polymer obtained falls and it is unpreferable.
[0029]
As the polymerization reaction proceeds, a polymer can be produced in supercritical carbon dioxide. After completion of the polymerization, the polymer can be easily taken out from the reaction system by lowering the temperature and pressure and discharging carbon dioxide. The polymer is usually taken out as a polymer fine powder, and can be directly used as a fine powder product without undergoing further crushing and the like. Moreover, it can also be set as a product after removing the said dispersing agent as needed.
[0030]
Examples of a method for removing the dispersant from the obtained polymer include alcohols such as methanol, ethanol and propanol, ketones such as acetone and methyl ethyl ketone, ethers such as diethyl ether and diisopropyl ether, and acetonitrile. It can be easily removed by washing with nitriles and aromatics such as benzene, toluene and xylene, or alkaline aqueous solutions such as aqueous sodium hydroxide, aqueous potassium hydroxide and aqueous calcium hydroxide.
[0031]
The polymer obtained by the production method of the present invention preferably contains a constitutional unit based on an ethylenically unsaturated monomer. The molecular weight of the polymer, as a weight average molecular weight 1,000 to 1,000,000, preferably can be 10,000 to 300,000. Moreover, powders, such as a fine powder , can be obtained by the said polymerization reaction in the manufacturing method of this invention , The average particle diameter of the particle | grain can be 0.1-50 micrometers, Preferably it can be 0.1-20 micrometers. . By having such an average particle diameter, for example, when used as a powder paint, a coating film having excellent smoothness can be provided.
[0032]
The manufacturing method of the present invention, it is possible to obtain a high-quality fine powder having a uniform particle size.
[0033]
The polymer obtained by the present invention can be suitably used as a material for paints, inks, adhesives, molded articles, cosmetic materials, medical products and the like.
[0034]
【The invention's effect】
In the method for producing a polymer of the present invention, a polymer having a low environmental load, a simple process, a high yield, and high versatility can be efficiently obtained. Furthermore, a polymer fine powder can be produced as a polymer, and a high-quality fine powder having a uniform particle size can be easily obtained.
[0036]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these.
[0037]
The measurement methods used in the examples are as follows.
1. Measurement of weight average molecular weight;
Gel permeation chromatography (GPC);
Model: manufactured by Tosoh Corporation, GPC-8020,
Conditions: Column: Tosoh Corporation, TSKgel-G3000PW _XL , Tosoh Corporation, TSKgel-G6000PW _XL
Column temperature: 45 ° C.
Flow rate: 1 mL / min
Eluent: phosphate buffer (pH 7.4, 20 mM)
Standard sample: Polyethylene glycol detector: UV (Tosoh UV-8020) and RI (Tosoh RI-8020) are used.
2. Measuring the particle size of the powder;
Model: Scanning electron microscope (S-80 manufactured by Hitachi, Ltd.)
Measurement conditions: measured at an acceleration voltage of 15 KV and 20 KV, and the average particle diameter of 100 particles was defined as the particle diameter.
3. Measurement of glass transition temperature It was carried out with a differential scanning calorimeter DSC (Seiko DSC-220).
[0038]
[Example 1]
A 54-mL metal high-pressure polymerization vessel having a stirrer and a temperature measuring device is heated to 31 ° C. or higher, and 5.40 g of methyl methacrylate is added to the polymerization vessel, 21.6 mg of AIBN is used as a polymerization initiator, and docosanoic acid having 22 carbon atoms. 0.54 g was added, and then carbon dioxide was injected, and heated and pressurized quickly so that the temperature in the polymerization vessel was 65 ° C. and the pressure was 300 kg / cm ² . After reaching the predetermined temperature and pressure, the monomer was polymerized for 24 hours while stirring at 700 rpm. After completion of the polymerization, the temperature and pressure in the polymerization vessel were lowered, and then carbon dioxide was discharged. White fine powder was obtained in the polymerization vessel, and the yield was 5.08 g.
[0039]
The polymer fine powder had an Mw (weight average molecular weight) of 180,000 as measured by GPC as described above. Moreover, observation of this polymer fine powder with a scanning electron microscope confirmed that it was a fine powder having a particle size of 3.3 μm. FIG. 1 shows a photograph of the results of observation by a scanning electron microscope.
[0040]
It was 105 degreeC when the glass transition point (Tg) of this polymer fine powder was measured.
[0041]
[Example 2]
A 54 mL metal high-pressure polymerization vessel having a stirrer and a temperature measuring device was heated to 31 ° C. or more, and 3.78 g of methyl methacrylate, 1.62 g of n-butyl methacrylate were added to the polymerization vessel as a polymerization initiator. 21.6 mg of AIBN and 0.54 g of docosanoic acid having 22 carbon atoms were added, and then carbon dioxide was injected, and heated and pressurized quickly so that the temperature in the polymerization vessel was 65 ° C. and the pressure was 300 kg / cm ² . . After reaching the predetermined temperature and pressure, the monomer was polymerized for 24 hours while stirring at 700 rpm. After completion of the polymerization, the temperature and pressure in the polymerization vessel were lowered, and then carbon dioxide was discharged. White fine powder was obtained in the polymerization vessel, and the yield was 5.23 g.
[0042]
The polymer fine powder had an Mw (weight average molecular weight) of 210,000 as measured by GPC as described above. Further, observation of this polymer fine powder with a scanning electron microscope confirmed that it was a fine powder having a particle size of 2.8 μm.
[0043]
It was 75 degreeC when the glass transition point of this polymer fine powder was measured.
[0044]
[Example 3]
A 54-mL metal high-pressure polymerization vessel having a stirrer and a temperature measuring device is heated to 31 ° C. or higher, and 5.40 g of methyl methacrylate is added to the polymerization vessel, 21.6 mg of AIBN is used as a polymerization initiator, and docosanoic acid having 22 carbon atoms. 3.40 g was added, and then carbon dioxide was injected, and immediately heated and pressurized so that the temperature in the polymerization vessel was 65 ° C. and the pressure was 300 kg / cm ² . After reaching the predetermined temperature and pressure, the monomer was polymerized for 24 hours while stirring at 700 rpm. After completion of the polymerization, the temperature and pressure in the polymerization vessel were lowered, and then carbon dioxide was discharged. White fine powder was obtained in the polymerization vessel, and the yield was 7.30 g.
[0045]
The polymer fine powder had an Mw (weight average molecular weight) of 109,000 as measured by GPC as described above. Further, observation of this polymer fine powder with a scanning electron microscope confirmed that it was a fine powder having a particle size of 2.3 μm.
It was 105 degreeC when the glass transition point of this polymer fine powder was measured.
[0046]
[Example 4]
A 54-mL metal high-pressure polymerization vessel having a stirrer and a temperature measuring device was heated to 31 ° C. or more, and 5.40 g of methyl methacrylate was added to the polymerization vessel, 21.6 mg of AIBN as a polymerization initiator, and myristic acid having 14 carbon atoms. 0.54 g was added, and then carbon dioxide was injected, and heated and pressurized quickly so that the temperature in the polymerization vessel was 65 ° C. and the pressure was 300 kg / cm ² . After reaching the predetermined temperature and pressure, the monomer was polymerized for 24 hours while stirring at 700 rpm. After completion of the polymerization, the temperature and pressure in the polymerization vessel were lowered, and then carbon dioxide was discharged. White fine powder was obtained in the polymerization vessel, and the yield was 5.21 g.
The polymer fine powder had an Mw (weight average molecular weight) of 140,000 as measured by GPC as described above. Further, observation of this polymer fine powder with a scanning electron microscope confirmed that it was a fine powder having a particle size of 3.4 μm.
[0047]
It was 105 degreeC when the glass transition point of this polymer fine powder was measured.
[0048]
[Example 5]
A metal high-pressure polymerization vessel having a volume of 54 mL having a stirrer and a temperature measuring device was heated to 31 ° C. or more, 5.40 g of styrene was added to the polymerization vessel, 21.6 mg of AIBN was used as a polymerization initiator, and 0.2 wt. 54 g was added, and then carbon dioxide was injected, and immediately heated and pressurized so that the temperature in the polymerization vessel was 65 ° C. and the pressure was 300 kg / cm ² . After reaching the predetermined temperature and pressure, the monomer was polymerized for 24 hours while stirring at 700 rpm. After completion of the polymerization, the temperature and pressure in the polymerization vessel were lowered, and then carbon dioxide was discharged. White fine powder was obtained in the polymerization vessel, and the yield was 5.06 g.
[0049]
When this polymer fine powder was measured by GPC as described above, Mw (weight average molecular weight) was 190,000. Further, observation of this polymer fine powder with a scanning electron microscope confirmed that it was a fine powder with a particle size of 2.0 μm.
[0050]
It was 100 degreeC when the glass transition point of this polymer fine powder was measured.
[0051]
[Comparative Example 1]
A 54-mL metal high-pressure polymerization vessel having a stirrer and a temperature measuring device was heated to 31 ° C. or higher, and 5.40 g of methyl methacrylate was added to the polymerization vessel, 21.6 mg of AIBN as a polymerization initiator, and poly (polyethylene) as a surfactant. (1,1-dihydroperfluorooctyl acrylate) (0.54 g) was added, and then carbon dioxide was injected. The mixture was quickly heated and pressurized so that the temperature in the polymerization vessel was 65 ° C. and the pressure was 300 kg / cm ² . . After reaching the predetermined temperature and pressure, the monomer was polymerized for 24 hours while stirring at 700 rpm. After completion of the polymerization, the temperature and pressure in the polymerization vessel were lowered, and then carbon dioxide was discharged. In the polymerization vessel, unreacted monomer, white polymer fine powder and pellet-shaped polymer were obtained, and the yield of the polymer fine powder was 3.10 g.
[0052]
Observation of this fine polymer powder with a scanning electron microscope revealed that the fine particles were non-uniform aggregates with the size of the associated fine particles. FIG. 2 shows a photograph of the results of observation by a scanning electron microscope.
[0053]
[Comparative Example 2]
A 54-mL metal high-pressure polymerization vessel having a stirrer and a temperature measuring device is heated to 31 ° C. or more, and 5.40 g of methyl methacrylate and 21.6 mg of AIBN as a polymerization initiator are added to the polymerization vessel. Carbon was injected and immediately heated and pressurized so that the temperature in the polymerization vessel was 65 ° C. and the pressure was 300 kg / cm ² . After reaching the predetermined temperature and pressure, the monomer was polymerized for 24 hours while stirring at 700 rpm. After 24 hours, the temperature and pressure in the polymerization vessel were lowered, and carbon dioxide was discharged. A colorless transparent pellet-like polymer and unreacted methyl methacrylate were observed in the polymerization vessel, and it was confirmed that the polymerization reaction was not completed.
[0054]
[Comparative Example 3]
A 54-mL metal high-pressure polymerization vessel having a stirrer and a temperature measuring device is heated to 31 ° C. or more, and 5.40 g of methyl methacrylate is added to the polymerization vessel, 21.6 mg of AIBN is used as a polymerization initiator, and acetic acid having 2 carbon atoms is added. .54 g was added, and then carbon dioxide was injected, and immediately heated and pressurized so that the temperature in the polymerization vessel was 65 ° C. and the pressure was 300 kg / cm ² . After reaching the predetermined temperature and pressure, the monomer was polymerized for 24 hours while stirring at 700 rpm. After completion of the polymerization, the temperature and pressure in the polymerization vessel were lowered, and then carbon dioxide was discharged. A colorless and transparent pellet-like polymer and methyl methacrylate were observed in the polymerization vessel, and it was confirmed that the polymerization reaction was not completed.
[Brief description of the drawings]
FIG. 1 is a photograph showing the observation results of the polymer obtained in Example 1 with a scanning electron microscope.
FIG. 2 is a photograph showing the observation result of the polymer obtained in Comparative Example 1 with a scanning electron microscope.

Claims (2)

  A polymer characterized by polymerizing a polymerizable monomer in supercritical carbon dioxide in the presence of a non-polymerizable dispersant having at least 10 carbon atoms and having at least one carboxyl group in the molecule. Production method.   The method for producing a polymer according to claim 1, wherein the non-polymerizable dispersant is a fatty acid having 14 or more carbon atoms.

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