JP2003165801A - Method for producing isopropyl methacrylamide polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polymer having a high gas hydrate production controllability at a high conversion and a low molecular weight. SOLUTION: Isopropyl methacrylamide is used as a monomer, and at least one selected from the group consisting of alcohols, ketones, ethers, esters, amides, and nitriles is used as a solvent, and water is contained in the polymerization system. A method for producing an isopropyl methacrylamide-based polymer, which is contained in an amount of 2 to 50% by mass. A hydrate production control agent comprising the polymer obtained by the above production method. A hydrate production control method using the polymer obtained by the above production method.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polymer having a low monomer content and a low molecular weight under the condition that the same amount of a polymerization initiator is used. The present invention also relates to a method for producing a polymer useful as a gas hydrate production control agent and the like.

[0002]

2. Description of the Related Art Isopropylmethacrylamide monomers are generally polymerized by using a polymerization initiator in a solvent system in which the monomer and the polymerization initiator are dissolved. For example, an isopropyl methacrylamide polymer has a cloud point in water, so that when the polymerization is carried out at a temperature higher than the cloud point, the polymer is precipitated as the polymerization proceeds, and thus the polymerization is difficult to proceed. Therefore, the method of polymerizing with an organic solvent is preferable, but it is expensive to remove the organic solvent, and therefore it is preferable to use a solvent which may be mixed in the use scene. By the way, the isopropyl methacrylamide-based polymer is disclosed in, for example, International Publication WO96.
As disclosed in Japanese Patent Publication No./41786, it is known that the polymer exhibits a very high hydrate inhibitor effect. There is a need for an efficient polymerization process with a solvent that can be added to the pipeline without removal during use.

[0003]

The object of the present invention is to polymerize isopropylmethacrylamide in a solvent,
It is to provide a method for producing an N-isopropylmethacrylamide polymer having a small amount of residual monomer and a small molecular weight with the same amount of initiator, and a method for producing a polymer having high gas hydrate formation controllability. To provide.

[0004]

Means for Solving the Problems As a result of studying a polymerization method of N-isopropylmethacrylamide, the present inventors have found that
The inventors have found that a polymer having a small content of N-isopropylmethacrylamide and a small molecular weight can be obtained by the following method, and thus the present invention has been accomplished.

That is, the present invention uses at least one selected from the group consisting of isopropyl methacrylamide as a monomer, alcohols, ketones, ethers, esters, amides, and nitriles as a solvent, A method for producing an isopropyl methacrylamide-based polymer, characterized in that water is contained in an amount of 2 to 50% by mass in the polymerization system.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The N-isopropyl methacrylamide polymer of the present invention means an N-isopropyl methacrylamide homopolymer or a copolymer of N-isopropyl methacrylamide copolymerizable polymer, N-
It is preferable to contain 50 mol% or more of the isopropyl methacrylamide component.

As the copolymer of N-isopropylmethacrylamide and a copolymerizable polymer, for example, N-ethyl (meth) acrylamide as an amphipathic monomer,
N-cyclopropyl (meth) acrylamide, N-isopropylacrylamide, Nn-propyl (meth) acrylamide, N-methyl-N-ethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide,
N-methyl-N-isopropyl (meth) acrylamide, N-methyl-Nn-propyl (meth) acrylamide, N- (meth) acryloylpyrrolidine, N- (meth) acryloylpiperidine, N-2-ethoxyethyl (meth ) Acrylamide, N-3-methoxypropyl (meth) acrylamide, N-3-ethoxypropyl (meth) acrylamide, N-3-isopropoxypropyl (meth) acrylamide, N-3- (2-methoxyethoxy) propyl (meth ) Acrylamide, N-3-
(2-Methoxyethoxy) propyl (meth) acrylamide, N-tetrahydrofurfuryl (meth) acrylamide, N-1-methyl-2-methoxyethyl (meth) acrylamide, N-1-methoxymethylpropyl (meth) acrylamide, N -(2,2-dimethoxyethyl) -N- (meth) acrylamide, N- (1,3-dioxolan-2-ylmethyl) -N- (meth) acrylamide, N-2-methoxyethyl-N- (meth) Acrylamide, N-2-methoxyethyl-Nn-propyl (meth) acrylamide, N-2-methoxyethyl-N
-Isopropyl (meth) acrylamide, N, N-di (2-methoxyethyl) (meth) acrylamide, N-
Vinylpyrrolidone, N-vinylcaprolactam, N-isopropenylpyrrolidone, N-isopropenylcaprolactam and the like can be mentioned.

Further, for example, as a hydrophilic monomer, N
-(Meth) acrylamide, N-methyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide,
N- (meth) acryloylmethylhomopiperazine, N-
(Meth) acryloylmethylpiperazine, N-2-hydroxyethyl-N- (meth) acrylamide, N-3-
Hydroxypropyl (meth) acrylamide, N-2-methoxyethyl (meth) acrylamide, N-3-morpholinopropyl (meth) acrylamide, N- (meth) acryloylmorpholine, N-2-methoxyethyl-N-
Methyl (meth) acrylamide, (meth) acrylic acid and salts thereof, 2-hydroxyethyl (meth) acrylate, ethylene glycol (meth) acrylate, diethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, propylene glycol (meth) acrylate , Butanediol (meth) acrylate, trimethylolpropane (meth) acrylate, dimethylaminoethyl (meth) acrylate, dimethylamidopropyl (meth) acrylamide, vinyl acetate, vinyl propionate, methyl vinyl ether, ethyl vinyl ether, 2-vinyl-2 -Oxazoline, 2
-Vinyl-4-methyl-2-oxazoline, 2-isopropyl-2-oxazoline, N-vinylacetamide,
N-vinyl-N-methylacetamide, N-vinylformamide, N-vinyl-N-methylformamide, N-
Vinyl-N-n-propylpropionamide, N-vinyl-N-methylpropionamide, N-vinyl-N-i
-Propylpropionamide, N-vinylpropionamide, vinyl butyrate, N-allylamide, maleic acid, vinylimidazole, dimethylaminoethyl (meth) acrylate methyl chloride salt, dimethylaminoethyl (meth) acrylate benzyl chloride salt, 2
-(Meth) acrylamido-2-methylpropanesulfonic acid and its salts, (meth) acrylamidomethanesulfonic acid and its salts, (meth) acrylamidoethanesulfonic acid and its salts, 2- (meth) acrylamido-n-butanesulfonic acid And salts thereof, glycosyloxyethyl acrylate, glycosyloxyethyl methacrylate, glycosyloxyethyl-α-ethyl acrylate, glycosyloxyethyl-β-methyl acrylate, glycosyloxyethyl-β, β-dimethyl acrylate, glycosyloxyethyl-β-ethyl. Acrylate, glycosyloxyethyl-β, β-diethyl acrylate, ethylene glycol, propylene glycol and the like can be mentioned.

Further, for example, as a hydrophobic monomer,
Alkyl (meth) acrylates, alkyl (meth) acrylamides, heterocyclic (meth) acrylates, heterocyclic (meth) acrylamides, vinyls that may have a lower alkyl group or a halogen atom as a substituent on the benzene ring Examples thereof include benzenes.

The weight average molecular weight of the polymer obtained in the present invention is preferably in the range of 500 to 10,000. The smaller the weight average molecular weight, the higher the mobility of polymer molecules in water. Therefore, the higher the production controllability with respect to gas hydrate, the higher the proportion, the higher the ratio of the sites showing the production controllability in the polymer.

The method for producing the polymer of the present invention is solution polymerization using a mixed solvent of the following solvent and water. The content of water is 2 to 50% by mass. When the water content is lower than 2% by mass, the effect of reducing the amount of residual monomer and the ability to control gas hydrate formation is hardly exhibited, and when it is higher than 50% by mass, the same effect is not recognized. The water content is measured by the Karl Fischer method. The water content (mass%) in the present invention is represented by the following formula.

Moisture content (mass%) = water mass / (polymerization solution mass-polymer effective component mass) × 100 The solvent used for the polymerization is methanol, ethanol, butanol, ethylene glycol, propylene glycol,
Alcohols such as 1,3-propanediol and glycerol, ketones such as acetone, methyl ethyl ketone and methyl butyl ketone, diethyl ether, 1,4-dioxane, tetrahydrofuran, 2-ethoxyethanol,
A group consisting of ethers such as 2-methoxyethanol and 2- (2-methoxyethoxyethanol), esters such as ethyl acetate, butyl acetate and methyl propionate, amides such as (methyl) pyrrolidone, and nitriles such as acetonitrile. At least one selected from is used. Alcohols such as methanol, ethanol, butanol, ethylene glycol, propylene glycol, 1,3-propanediol and glycerol are preferable, and ethylene glycol is more preferable, but two or more kinds of solvents may be mixed and used. Among them, by mixing a small amount of methanol, the isopropyl methacrylamide sublimate at the time of polymerization can be prevented from adhering to the wall of the polymerization vessel or the condenser, and the solvent itself can exhibit the gas hydrate formation control performance, so that it can be used as a solvent. Is preferred as

The initiator used in the present invention is not limited,
Azo initiators, peroxides, redox initiators, photoinitiators, etc., and combinations thereof are possible. It is particularly preferable to use a nonionic azo initiator. Nonionic azo initiators include 2,2'-azobis (4-methoxy-2,
4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 2,2'-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide},
2,2'-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) ethyl] propionamide},
2,2'-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], 2,2'-azobis (2-methylpropionamide) dihydrate, 2,2'-
Azobis (2,4,4-trimethylpentane), dimethyl 2,2′-azobis (2-methylpropionate),
2,2′-azobis [2- (hydroxymethyl) propionnitrile], 2-cyano-2-propylazoformamide and the like can be mentioned.

A chain transfer agent may be used in the polymerization. The chain transfer agent is preferably a nonionic one, for example, alkyl mercaptans such as n-butyl mercaptan and n-octyl mercaptan, formaldehyde, acetaldehyde, propionaldehyde, n.
-Butyraldehyde, isobutyraldehyde, diacetyl sulfide, ethyl thioglycolate, 2-mercaptoethanol, 1,3-mercaptopropanol, 3-
Examples thereof include mercaptopropane-1,2-diol, 1,4-mercaptobutanol, thioglycerin, diethanol sulfide, thiodiglycol, ethylthioethanol, thiourea and allyl alcohol. Among them, alkyl mercaptans, n-butyraldehyde, isobutyraldehyde, diacetyl sulfide, ethyl thioglycolate, 2-mercaptoethanol, 1,3-mercaptopropanol, 3-mercaptopropane-1,2.
-Diols are preferred. Among these, 2-mercaptoethanol, 1,3-mercaptopropanol, 3-
Mercaptans having a hydroxyl group, such as mercaptopropane-1,2-diol, are preferable because the obtained polymer has high gas hydrate production control performance.

The timing of addition of the chain transfer agent is not particularly limited, but it is preferable to add a part of the chain transfer agent at the time of charging the monomer, from the viewpoint of suppressing generation of a high molecular weight component due to polymerization at the time of charging or at the time of heating.

The polymerization temperature is not particularly limited, but is 30 to 17
0 degreeC is preferable and 60 degreeC-130 degreeC is more preferable.

The weight average molecular weight of the polymer obtained in the present invention is, for example, "Mori et al, Anal. Chem., 55 , 2414-241.
6 (1983). ”And the like.

The polymer obtained in the present invention is particularly useful as a hydrate formation controlling agent.

The gas hydrate production control method of the present invention comprises adding the above-mentioned gas hydrate production control agent of the present invention to a system capable of producing gas hydrate. As the gas hydrate production control agent, other production control agents may be used in combination. Examples of the production control agent that can be used in combination include hydrophilic polymers, ethylene glycol, triethylene glycol, methanol, ethanol, acetone and the like.
Hydrophilic polymers are preferred. When another production control agent is used in combination, the proportion of the polymer obtained in the present invention is usually 1 to 80% by mass in the production control agent, preferably 20 to 6
It is 0% by mass, particularly preferably 30 to 60% by mass.

The term "system capable of producing gas hydrate" means, for example, J. Long, A. Lederhos, A. Sum, R.
Christiansen, ED Sloan; Prep. 73rd Ann. GPA Co
nv., 1994, pp. 1-9, such as a system in which a substance that forms a gas hydrate is dissolved in an aqueous solvent. Such a system can be operated under certain pressure and temperature conditions.
Gas hydrate is deposited as a crystalline substance.

Examples of substances that form gas hydrates include gases such as carbon dioxide, nitrogen, oxygen, hydrogen sulfide, argon, xenon, methane, ethane and propane, and liquids such as tetrahydrofuran.

As a system capable of producing gas hydrate, for example, in a natural gas well or an oil well, a water phase in which a gas such as ethane or propane is dissolved in an aqueous solvent such as water or seawater is liquefied gas or crude oil. Examples thereof include systems that exist in the oil phase in a suspended / dispersed state, systems in which a gas phase such as natural gas exists in the aqueous phase, and the like.

The method of adding the gas hydrate formation control agent of the present invention to a system capable of forming gas hydrate is not particularly limited, but it is preferable to add it after dissolving it in water and / or a solvent miscible with water. . Water-miscible solvent refers to a solvent that mixes with water in any proportion, for example,
Examples include methanol, ethanol, acetone and ethylene glycol.

The lower limit of the amount of the gas hydrate formation control agent added is 0.01 part by mass or more, preferably 1 part by mass or more, relative to 100 parts by mass of free water contained in the system capable of forming gas hydrate. Is more preferable. The upper limit is 1
The amount is preferably 00 parts by mass or less, more preferably 50 parts by mass or less. As the amount of the gas hydrate production control agent added increases, the gas hydrate stabilizing effect improves, and as the amount decreases, the system viscosity decreases and the fluidity improves.

When the gas hydrate production control agent of the present invention is used, various additives such as a rust preventive agent, a lubricant, a dispersant, a scale adhesion preventive agent and a corrosion inhibitor are used in combination. Good.

[0026]

EXAMPLES The present invention is described in detail below with reference to examples and comparative examples, but the present invention is not limited thereto.

<Measurement of Effective Content of Obtained Polymerization Solution> The amounts of ethylene glycol, methanol and residual N-isopropylmethacrylamide monomer in the polymerization solution were measured by gas chromatography, and the water content was measured by a Karl Fischer apparatus. The rest was used as the effective component.

<Polymer Molecular Weight Measuring Device> The molecular weight of the polymer was measured by the following device and measuring conditions.

Equipment: Tosoh 8010 system (R
I detector) Column: Shodex GPC KD-806M (8 × 300 mm) Ultrahydrogel 120 6 μ (8 × 300 mm) Column temperature: 40 ° C. (constant bath) Mobile phase: Dimethylformamide 0.01 M Lithium bromide Flow rate: 0.8 ml / min Standard polymer for molecular weight conversion: Standard polyethylene glycol Sample concentration: 0.1% by mass (DMF / LiBr solution) <Evaluation device for hydrate production control agent> As an index of gas hydrate production inhibition performance of gas hydrate production control agent The gas hydrate formation temperature and the gas hydrate decomposition completion temperature, which is an index of gas hydrate stabilization performance, were measured using the apparatus shown in FIG.

In this apparatus, the reaction high-pressure cell 4 has an internal capacity of 100 ml and is designed for normal pressure resistance up to 20 MPa. This cell is equipped with a gas introduction line 1, a liquid introduction line 2, a purge line 3, a cell internal temperature gauge 5, a cell internal pressure gauge 6 and a reaction cell internal agitator 7. The entire cell is housed inside the thermostat 8, and the temperature inside the cell can be adjusted by the temperature of the thermostat 8. In the reaction high-pressure cell 4,
Internal observation windows (not shown) having a diameter of 3 cm are provided at three places so that the inside of the cell can be observed.

<Evaluation Method of Production Inhibition Performance> The gas hydrate production inhibition performance was evaluated as follows. That is,
A 0.5 mass% aqueous solution of a gas hydrate production control agent to be evaluated was introduced from the liquid introduction line 2, and methane gas was introduced from the gas introduction line 1 to adjust the pressure inside the cell to 10
The pressure was set to MPa, and the temperature inside the cell was set to 20 ° C., which is a temperature obviously higher than the equilibrium temperature at which methane hydrate is formed at that pressure. Then, while stirring the inside of the cell, -4 ° C
When the temperature inside the cell is gradually lowered at / hr, it is observed that methane hydrate is generated inside the cell at a certain temperature. Due to the formation of methane hydrate, the pressure inside the cell is lowered, and at the same time, since the formation of gas hydrate is an exothermic reaction, the temperature inside the cell is slightly increased. It was evaluated that the gas hydrate formation inhibiting performance was higher as the temperature inside the cell at the time when the pressure started to decrease greatly, that is, the lower the methane hydrate formation temperature.

The value without additives in this evaluation is 8.
It was 9 ° C.

<Equilibrium Stabilizing Performance Evaluation Method> The equilibrium stabilizing performance was evaluated as follows. That is, after measuring the methane hydrate production temperature in the performance evaluation described above, lower the temperature of the constant temperature bath by 2 ° C from the methane hydrate production start temperature, and leave it until the cell internal pressure and cell internal temperature become constant. To do. After that, the temperature inside the cell was set to 4 ° C / hr.
When it is raised by, the methane hydrate in the cell begins to decompose and finally it is completely separated into water and methane gas.
It was evaluated that the higher the in-cell temperature at this time, that is, the decomposition end temperature of methane hydrate, the greater the equilibrium stabilization performance for gas hydrate.

In this evaluation, the value without additives was 14.
It was 2 ° C.

<Evaluation Method of Kinetic Stabilizing Performance> The kinetic stabilizing performance of decreasing the decomposition rate of gas hydrate and delaying the decomposition of gas hydrate was evaluated as follows. That is, after the methane hydrate was produced by the same procedure as the measurement of the methane hydrate production temperature in the evaluation of production inhibition performance described above, the constant temperature bath temperature was set to 2 ° C., and the cell internal pressure and the cell internal temperature were Leave it until it becomes constant. Then, the methane gas in the cell is discharged to bring the cell internal pressure to 2 MPa. The cell was sealed under these conditions, and the time until the pressure inside the cell became constant was measured. It was evaluated that the longer this time (hereinafter referred to as “kinetic decomposition delay time”), the greater the kinetic stabilization performance in the decomposition of methane hydrate. The value without additive in this evaluation was 40 minutes.

Example 1 A stirrer, a cooling pipe, a nitrogen introducing pipe, and a thermocouple were set.
In a 000 ml separable flask, 240 g of ethylene glycol and 50 g of ion-exchanged water were added, and 320 g of N-isopropyl methacrylamide (manufactured by Mitsubishi Rayon Co., Ltd.) and 8 g of methanol were put in the oil bath while heating and stirring at 40 ° C. Then, after heating to 60 ℃,
While stirring, 1 g of 2,2′-azobis (2-methylbutyronitrile) (Wako Pure Chemical Industries, Ltd .: V-59), 2,
0.5 g of 2′-azobis (cyclohexane-1-carbonitrile) (V-40 manufactured by Wako Pure Chemical Industries, Ltd.) and 24 g of thioglycerol were added, and the mixture was further heated and polymerized by stirring at 100 ° C. for 4 hours, A polymer solution was obtained. Obtained N
-Effective amount of isopropyl methacrylamide polymer is 5
It was 0.3 mass%. The amount of residual N-isopropylmethacrylamide in the polymerization solution was 5% by mass. The molecular weight of the obtained N-isopropyl methacrylamide polymer was measured by GPC using a dimethylformamide / lithium bromide solution as a mobile phase. As a result, the weight average molecular weight was 2200 in terms of standard polyethylene glycol. The obtained N-isopropyl methacrylamide polymer was diluted with distilled water so as to have a concentration of 0.5 mass% in terms of effective component, and the gas hydrate formation control ability was measured. As a result, the gas hydrate formation temperature was 3. At 0 ° C., the gas hydrate decomposition completion temperature was 26.7 ° C., and the kinetic decomposition delay time was 660 minutes.

Example 2 The amount of ethylene glycol was 200 g, and the amount of water was 90 g.
Polymerization was performed in the same manner as in Example 1 except that the above was used to obtain a polymer solution. The evaluation results of the obtained polymerization liquid are also shown in Table 1.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that the amount of ethylene glycol was 290 g and water was not added to obtain a polymer solution. The evaluation results of the obtained polymerization liquid are also shown in Table 1.

Comparative Example 2 Polymerization was carried out in the same manner as in Example 1 except that the amount of ethylene glycol was 285 g and the amount of water was 5 g to obtain a polymer solution. The evaluation results of the obtained polymerization liquid are also shown in Table 1.

Comparative Example 3 The amount of ethylene glycol was 90 g, and the amount of water was 200 g.
Polymerization was performed in the same manner as in Example 1 except that the above was used to obtain a polymer solution. The evaluation results of the obtained polymerization liquid are also shown in Table 1.

[0041]

[Table 1]

[0042]

EFFECT OF THE INVENTION By using the method for producing an N-isopropyl (meth) acrylamide polymer of the present invention, a low molecular weight polymer with a high conversion rate can be obtained despite the same amount of initiator. The obtained polymer has high hydrate control ability.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for evaluating the performance of a gas hydrate production control agent.

[Explanation of symbols]

1 gas introduction line 2 liquid introduction line 3 Purge line 4 High-pressure cell for reaction 5 Thermometer in reaction cell 6 Pressure gauge in reaction cell 7 Stirrer in reaction cell 8 constant temperature bath

Claims (5)

[Claims] 1. At least one selected from the group consisting of isopropyl methacrylamide as a monomer and alcohols, ketones, ethers, esters, amides, and nitriles as a solvent is used in a polymerization system. A method for producing an isopropyl methacrylamide-based polymer, which comprises containing 2 to 50% by mass of water. 2. The method for producing an isopropyl methacrylamide polymer according to claim 1, wherein the solvent is an alcohol. 3. The method for producing an isopropylmethacrylamide polymer according to claim 1, wherein the solvent is ethylene glycol. 4. A hydrate production control agent comprising a polymer obtained by the production method according to claim 1. 5. A hydrate production control method using the polymer obtained by the production method according to any one of claims 1 to 3.