Polyethyleneimine production method and polyethyleneimine

Abstract

A polyethyleneimine production method provided herein includes a polymerization step for polymerizing ethyleneimine at a temperature of 30°C or higher in the presence of a superacid, wherein the polymerization step is performed using an alcohol / water mixed solvent. According to this production method, polyethyleneimine having a high secondary amine content can be produced even under mild conditions.

Description

Method for producing polyethyleneimine and polyethyleneimine

[0001] The present invention relates to a method for producing polyethyleneimine and polyethyleneimine.

[0002] Polyethyleneimine, which is a polymer having a large number of amino groups, has various useful functions such as chelating ability and is used in various applications depending on its molecular weight. For example, polyethyleneimine belonging to the low molecular weight range and having a low viscosity is used as various dispersants and detergents, and polyethyleneimine belonging to the high molecular weight range and having a high viscosity is used as a binder or an adhesive.

[0003] For example, Patent Document 1 discloses a method for producing polyethyleneimine, which comprises a step of polymerizing ethyleneimine at a temperature of 25°C or lower in the presence of a superacid, wherein the number average molecular weight of the polyethyleneimine is 4000 or more and the degree of branching exceeds 0% and is 25% or less.

[0004] Japanese Unexamined Patent Application Publication No. 2021-155571

[0005] As described above, polyethyleneimine can be applied to various uses, but depending on the use, there is a desire to increase the content of secondary amine (secondary amino group) contained in polyethyleneimine.

[0006] Therefore, an object of the present invention is to provide a production method capable of producing polyethyleneimine having a large content of secondary amine even under mild conditions.

[0007] The present inventor conducted various studies to achieve the above object and arrived at the present invention. That is, the method for producing polyethyleneimine of the present disclosure comprises a polymerization step of polymerizing ethyleneimine at a temperature of 30°C or higher in the presence of a superacid, and the polymerization step is carried out using an alcohol / water mixed solvent.

[0008] According to this disclosure, polyethyleneimines with a high content of secondary amines (secondary amino groups) can be produced without employing excessive cooling conditions or complicated processes. Therefore, polyethyleneimines with a high content of secondary amines (secondary amino groups) can be produced efficiently. According to this disclosure, polyethyleneimines with a low molecular weight distribution for a similar molecular weight can be produced efficiently.

[0009] This figure shows the relationship between the number of secondary amines in polyethyleneimine obtained when ethyleneimine undergoes complete random polymerization, the number of secondary amines contained in the polyethyleneimine of this disclosure, and the number-average molecular weight.

[0010] The disclosure is described in detail below. Note that any combination of two or more of the preferred forms of the disclosure described below also constitutes a preferred form of the disclosure. The upper and lower limits of the numerical ranges described as preferred may be combined in any combination.

[0011] [Method for Producing Polyethyleneimine] The method for producing polyethyleneimine according to the present disclosure (hereinafter also referred to as the "method for producing polyethyleneimine") includes a step of polymerizing ethyleneimine at a temperature of 30°C or higher in the presence of a superacid (hereinafter also referred to as the "polymerization step"). According to the method for producing polyethyleneimine according to the present disclosure, it is possible to produce polyethyleneimine with a high secondary amine content without resorting to complicated production methods such as producing poly(2-ethyl-2-oxazoline) by ring-opening polymerization of 2-ethyl-2-oxazoline and then hydrolyzing it to produce polyethyleneimine. Furthermore, according to the method for producing polyethyleneimine according to the present disclosure, it is possible to produce polyethyleneimine with a high secondary amine content without employing harsh conditions such as excessive cooling. In other words, according to the method for producing polyethyleneimine with a high secondary amine (secondary amino group) content, even without employing excessive cooling conditions or complicated processes.

[0012] The superacid used in the manufacturing method of this disclosure is an acid that is more acidic than 100% by mass sulfuric acid. Superacids typically act as polymerization catalysts. By using superacids, the content of secondary amines contained in polyethyleneimine tends to increase in the polymerization reaction even at medium to low temperatures. Examples of superacids include trifluoromethanesulfonic acid, trifluoromethanesulfonic anhydride (e.g., ditrifluoromethanesulfonic anhydride), fluorosulfonic acid, bis(trifluoromethylsulfonyl)amine, chlorine-containing oxoacids such as perchloric acid and chloric acid, and nitric acid. One type of superacid may be used alone, or two or more types may be used in combination.

[0013] In the manufacturing method of this disclosure, the amount of superacid added is preferably 0.1 mol% or more, more preferably 0.3 mol% or more, and even more preferably 0.5 mol% or more in the reaction system, from the viewpoint of more efficiently obtaining polyethyleneimine with a high secondary amine content. The upper limit of the amount of superacid added is preferably 5 mol% or less, more preferably 3 mol% or less, and even more preferably 1 mol% or less in the reaction system, from the viewpoint of more efficiently obtaining polyethyleneimine with a high secondary amine content.

[0014] In the manufacturing method of this disclosure, the polymerization temperature is preferably 30°C or higher. By setting the reaction temperature to 30°C or higher, excessive cooling equipment may be omitted. Furthermore, polyethyleneimine with a higher secondary amine content tends to be obtained more efficiently. From this viewpoint, the reaction temperature is preferably 40°C or higher, more preferably 40°C or higher and 90°C or lower, even more preferably 40°C or higher and 80°C or lower, even more preferably 40°C or higher and 70°C or lower, and particularly preferably 40°C or higher and 65°C or lower.

[0015] In the manufacturing method of the present disclosure, although not particularly limited, it is preferable that 50 mol% or more of ethyleneimine is polymerized under the above conditions relative to 100 mol% of ethyleneimine used, more preferably 70 mol% or more of ethyleneimine is polymerized under the above conditions, even more preferably 80 mol% or more of ethyleneimine is polymerized under the above conditions, even more preferably 95 mol% or more of ethyleneimine is polymerized under the above conditions, and particularly preferably 100 mol% of ethyleneimine is polymerized under the above conditions.

[0016] In the polymerization step, the polymerization time is not particularly limited, but for example, if it is carried out in a batch reaction, it may be carried out for 30 minutes or more and 12 hours or less.

[0017] The polymerization step in the manufacturing method of this disclosure is preferably carried out using an alcohol / water mixed solvent. The alcohol / water mixed solvent is a mixed solvent containing at least an alcohol and water. By using the mixed solvent, polyethyleneimine with a higher secondary amine content tends to be obtained more efficiently. Furthermore, by using the mixed solvent, the molecular weight distribution (Mw / Mn) of the obtained polyethyleneimine tends to decrease when compared at similar molecular weights. In addition, by using an alcohol / water mixed solvent, the emergence of new characteristics based on the structural differences described above can also be expected.

[0018] The alcohol content in the mixed solvent is not particularly limited, but is preferably 5% by mass or more and 95% by mass or less, more preferably 10% by mass or more and 90% by mass or less, even more preferably 20% by mass or more and 80% by mass or less, and even more preferably 30% by mass or more and 70% by mass or less, based on 100% by mass of the mixed solvent. When the alcohol content is within the above range, polyethyleneimine with a higher secondary amine content tends to be obtained more efficiently. When the alcohol content is within the above range, the molecular weight distribution (Mw / Mn) of the obtained polyethyleneimine tends to decrease when compared with polyethyleneimine of similar molecular weight.

[0019] The water content in the mixed solvent is not particularly limited, but is preferably 5% by mass or more and 95% by mass or less, more preferably 10% by mass or more and 90% by mass or less, even more preferably 20% by mass or more and 80% by mass or less, and even more preferably 30% by mass or more and 70% by mass or less, based on 100% by mass of the mixed solvent.

[0020] The content of solvents other than water and alcohol (hereinafter referred to as "other solvents") in the mixed solvent is not particularly limited, but is preferably 0% by mass or more and 50% by mass or less, more preferably 0% by mass or more and 30% by mass or less, even more preferably 0% by mass or more and 20% by mass or less, and even more preferably 0% by mass or more and 10% by mass or less, based on 100% by mass of the mixed solvent. The mixed solvent does not have to contain other solvents.

[0021] The amount of solvent used in the polymerization step is preferably 10 to 1000 parts by mass, more preferably 50 to 500 parts by mass, and even more preferably 100 to 300 parts by mass, per 100 parts by mass of ethyleneimine used.

[0022] There are no particular restrictions on the alcohol in the mixed solvent, but it is preferable to use an alcohol that is homogeneous with water and is a two-component or three-component or more alcohol. For example, it is preferable to use an alcohol with 1 to 6 carbon atoms, and more preferably an alcohol with 2 to 4 carbon atoms.

[0023] There are no particular restrictions on the alcohol in the mixed solvent, but examples include methanol, ethanol, isopropanol, n-propanol, isobutanol, ethylene glycol, methyl cellosolve, and glycerin. One type of alcohol may be used alone, or two or more types may be used in combination.

[0024] Other solvents mentioned above include, but are not limited to, ketones such as acetone and methyl ethyl ketone; aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as hexane and cyclohexane; and halogenated hydrocarbons such as dichloromethane and chloroform. These solvents are optional and do not need to be used, and one or more may be used individually or in combination.

[0025] In the manufacturing method of this disclosure, an amine additive may be used as the base amine that serves as the starting point for polymerization. By adding an amine additive that serves as the starting point for polymerization, it tends to become easier to control the molecular weight of the resulting polyethyleneimine within a desired range.

[0026] As amine additives, for example, primary amines, secondary amines, etc., can be used. The molecular weight of the amine additive is not particularly limited, but for example, those in the range of 31 to 1000 can be used. Specifically, ethylenediamine, diethylenetriamine, ethanolamine, alkylamine, etc., are preferably used as amine additives. These amine additives may be used individually or in combination of two or more.

[0027] When an amine additive is added, the amount added is not particularly limited, but it may be, for example, 0 mol% or more, 0.01 mol% or more, or 0.1 mol% or more in the reaction system. From the viewpoint of suppressing a decrease in the molecular weight of the obtained polyethyleneimine, the upper limit of the amount of amine additive added is preferably 3 mol% or less.

[0028] In the polymerization step, it is preferable to use only ethyleneimine as the monomer, but monomers other than ethyleneimine (hereinafter also referred to as other monomers) may also be used. In the polymerization step, it is preferable that the amount of ethyleneimine used is 50 mol% or more and 100 mol% or less, more preferably 80 mol% or more and 100 mol% or less, even more preferably 90 mol% or more and 100 mol% or less, and particularly preferably 100 mol%.

[0029] There are no particular restrictions on the other monomers mentioned above, but examples include alkyleneimines other than ethyleneimines, such as propyleneimine.

[0030] The polymerization process is preferably carried out by batch polymerization, but it may also be carried out by continuous polymerization or semi-continuous polymerization. The polymerization process is not particularly limited, but it may be carried out under an inert atmosphere.

[0031] The material of the reaction vessel and other components used in the polymerization process is not particularly limited, but examples include stainless steel materials such as SUS304 and SUS316; Hastelloy®; titanium steel; glass-lined steel; and resin-lined steel.

[0032] The manufacturing method disclosed herein may optionally include a maturation step after the polymerization step. The maturation step is performed, for example, to promote the polymerization of a small amount of remaining ethyleneimine and to reduce the amount of remaining ethyleneimine.

[0033] The aging process is not particularly limited, but it is preferably carried out at a temperature higher than the polymerization temperature, and is not particularly limited, but may be carried out at a temperature of 100°C or higher and 180°C or lower. The aging process is not particularly limited and is optional, but may be carried out for, for example, 10 minutes or more and 10 hours or less.

[0034] The manufacturing method disclosed herein may optionally include a purification step after the polymerization step, or in parallel with the polymerization step. Examples of purification steps include a step of removing residual ethyleneimine and solvent by vacuum distillation, or a step of treating impurities with an ion exchange resin or adsorbent.

[0035] The manufacturing method disclosed herein may include any steps other than the polymerization step.

[0036] The manufacturing method of this disclosure can be used to produce the polyethyleneimine of this disclosure as described later. However, the manufacturing method of this disclosure may also be used to produce polymers other than the polyethyleneimine of this disclosure as described later.

[0037] As described above, the manufacturing methods of the present disclosure are exemplified as follows: [1] A method for producing polyethyleneimine, comprising a polymerization step of polymerizing ethyleneimine at a temperature of 30°C or higher in the presence of a superacid. [2] The manufacturing method according to [1], comprising a polymerization step of polymerizing ethyleneimine at a temperature of 30°C or higher in the presence of a superacid, wherein the polymerization step is carried out using an alcohol / water mixed solvent. [3] The manufacturing method according to [1] or [2], wherein the amount of superacid added in the reaction system is preferably 0.1 mol% or more and 5 mol% or less, more preferably 0.3 mol% or more and 3 mol% or less, and even more preferably 0.5 mol% or more and 1 mol% or less. [4] The manufacturing method according to any one of [1] to [3], wherein the reaction temperature (polymerization temperature) is preferably 40°C or higher, more preferably 40°C or more and 90°C or less, even more preferably 40°C or more and 80°C or less, even more preferably 40°C or more and 70°C or less, and particularly preferably 40°C or more and 65°C or less. [5] The manufacturing method according to any one of [1] to [4], wherein the alcohol content in the mixed solvent is preferably 5% to 95% by mass, more preferably 10% to 90% by mass, even more preferably 20% to 80% by mass, and particularly preferably 30% to 70% by mass, based on 100% by mass of the mixed solvent. [6] The manufacturing method according to any one of [1] to [5], wherein the alcohol in the mixed solvent is preferably an alcohol having 1 to 6 carbon atoms, more preferably an alcohol having 2 to 4 carbon atoms. [7] The manufacturing method according to any one of [1] to [6], wherein the water content in the mixed solvent is preferably 5% to 95% by mass, more preferably 10% to 90% by mass, even more preferably 20% to 80% by mass, and particularly preferably 30% to 70% by mass, based on 100% by mass of the mixed solvent. [8] The manufacturing method according to any one of [1] to [7], wherein the amount of solvent used in the polymerization step is preferably 10 to 1000 parts by mass, more preferably 50 to 500 parts by mass, and even more preferably 100 to 300 parts by mass, per 100 parts by mass of ethyleneimine used.[9] The manufacturing method according to any one of [1] to [8], wherein the amount of amine additive added in the reaction system is preferably 0 mol% to 3 mol%, 0.01 mol% to 3 mol%, or 0.1 mol% to 3 mol.

[10] The manufacturing method according to any one of [1] to [9], further comprising a maturation step, wherein the maturation step is preferably carried out at 100°C to 180°C.

[11] The manufacturing method according to any one of [1] to

[10] , wherein, with respect to 100 mol% of ethyleneimine used, preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, even more preferably 95 mol% or more, and particularly preferably 100 mol% is polymerized under the above conditions.

[0038] [Polyethyleneimine] The polyethyleneimine of this disclosure can be produced by the manufacturing method of this disclosure. However, the polyethyleneimine of this disclosure is not limited to polyethyleneimine produced by the manufacturing method of this disclosure. For example, it is exemplified that the polyethyleneimine may be produced by a manufacturing method comprising a polymerization step in which ethyleneimine is polymerized in the presence of a superacid at a temperature of 30°C or higher, preferably 40°C or higher and 90°C or lower, more preferably 40°C or higher and 80°C or lower, even more preferably 40°C or higher and 70°C or lower, and particularly preferably 40°C or higher and 65°C or lower, wherein the polymerization step is carried out using an aqueous solvent. However, from the viewpoint of producing polyethyleneimine having a good number of secondary amines even under mild conditions, it is preferable to produce it by a manufacturing method using an alcohol / water mixed solvent.

[0039] The polyethyleneimine of the present disclosure preferably has a higher secondary amine content than polyethyleneimine having the same number average molecular weight obtained when ethyleneimine is completely randomly polymerized. The ratio of the number of secondary amines to the number of secondary amines (hereinafter, also referred to as "ratio of the number of secondary amines" or "ratio of the number of secondary amines") of the polyethyleneimine of the present disclosure to the number of secondary amines of polyethyleneimine having the same number average molecular weight obtained when ethyleneimine is completely randomly polymerized is more preferably 1.35 or more, more preferably 1.35 or more and 1.78 or less, further preferably 1.37 or more, even more preferably 1.39 or more, and particularly preferably 1.55 or more. Depending on the use of polyethyleneimine, even when the molecular weight is relatively high, for example, there may be a demand for polyethyleneimine with a lower viscosity of its aqueous solution. However, within the above range, compared with polyethyleneimine having the same degree of molecular weight, the viscosity of its aqueous solution and the like tends to be lower.

[0040] On the other hand, the polyethyleneimine of the present disclosure more preferably has a ratio of the number of secondary amines to the number of secondary amines of polyethyleneimine having the same number average molecular weight obtained when ethyleneimine is completely randomly polymerized of 1.78 or less, more preferably 1.35 or more and 1.78 or less, further preferably 1.76 or less, and even more preferably 1.74 or less.

[0041] In the present invention, "ethyleneimine is completely randomly polymerized" means that ethyleneimine uniformly undergoes an addition reaction with primary amines and secondary amines so that the ratio of the number of primary amines:secondary amines:tertiary amines is 1:1:1. For example, polyethyleneimine that is substantially completely randomly polymerized can be produced by the method described later (the methods described in Comparative Examples 3 to 5).

[0042] Further, the number of secondary amines 13 can be calculated using C-NMR and Gel Permeation Chromatography (GPC).

[0043] When the ethyleneimine is completely randomly polymerized, the number of secondary amines in the polyethyleneimine obtained is as shown in Fig. 1 (refer to the straight line of "Ratio of the number of secondary amines: 1.00"). As shown in Fig. 1, when the number average molecular weight of the polyethyleneimine is plotted on the X-axis and the number of secondary amines contained in the polyethyleneimine is plotted on the Y-axis, the number of secondary amines in the polyethyleneimine obtained when the ethyleneimine is completely randomly polymerized can be expressed by the following formula. y = 0.00773x Therefore, when the number average molecular weight of the polyethyleneimine is x, the form in which the number of secondary amines contained in the polyethyleneimine is 0.010344x or more, the form in which it is 0.010344x or more and 0.013638x or less, or the form in which it is 0.011809x or more and 0.013638x or less is one of the preferred forms of the polyethyleneimine of the present disclosure.

[0044] The number average molecular weight (Mn) of the polyethyleneimine of the present disclosure is preferably 500 or more and 5500 or less, more preferably 600 or more and 5250 or less, and even more preferably 700 or more and 5000 or less. Within the above range, while being suitably adapted to a relatively wide range of uses of polyethyleneimine, the viscosity of its aqueous solution or the like tends to be suppressed lower. The number average molecular weight in the present invention can be measured by a known method using pullulan as a standard substance by gel permeation chromatography (GPC) as described later. The same applies to the method for measuring the weight average molecular weight (Mw).

[0045] The molecular weight distribution (Mw / Mn) of the polyethyleneimine of the present disclosure is preferably 1.5 or more and 5.0 or less, more preferably 1.7 or more and 4.8 or less, and even more preferably 1.9 or more and 4.6 or less. Within the above range, while being suitably adapted to a relatively wide range of uses of polyethyleneimine, the viscosity of its aqueous solution or the like tends to be suppressed lower.

[0046] The polyethyleneimine of this disclosure preferably has a degree of branching of 20% or more and 45% or less, more preferably 22% or more and 43% or less, and even more preferably 24% or more and 41% or less. Within the above range, when compared with polyethyleneimines of similar molecular weight, the viscosity of its aqueous solution tends to be lower.

[0047] In this disclosure, the degree of branching refers to a numerical value that indicates the ratio of tertiary amines to the total amount of tertiary and secondary amines contained in polyethyleneimine. The above degree of branching is the ratio of polyethyleneimine 13 By measuring C-NMR and obtaining a chart, the intensity ratio of carbon atoms bonded to tertiary amines to carbon atoms bonded to secondary amines is determined, thereby calculating the number of tertiary amines (a) and the number of secondary amines (b). The degree of branching (%) is then calculated from a and b using the following formula: Branching degree (%) = [a / (a ​​+ b)] × 100. Therefore, linear polyethyleneimine does not contain tertiary amines, and thus has a branching degree of 0%. In contrast, polyethyleneimine with maximum branching has a branching degree of 100%.

[0048] The polyethyleneimine of this disclosure preferably has a ratio of secondary amines to 100 mol% of the total of primary, secondary, and tertiary amines contained in the polyethyleneimine (secondary amine ratio) of 46 mol% or more. More preferably, it is 46 mol% or more and 75 mol% or less, even more preferably 48 mol% or more and 70 mol% or less, even more preferably 50 mol% or more and 60 mol% or less, and particularly preferably 51 mol% or more and 59 mol% or less. Note that the ratio of secondary amines is 13 It can be calculated using C-NMR.

[0049] The polyethyleneimine of this disclosure is preferably a homopolymer of polyethyleneimine, but may also be a copolymer of ethyleneimine and monomers other than ethyleneimine (hereinafter also referred to as other monomers). The monomer composition of the polyethyleneimine of this disclosure is preferably 50 mol% to 100 mol%, more preferably 80 mol% to 100 mol%, even more preferably 90 mol% to 100 mol%, even more preferably 95 mol% to 100 mol%, and particularly preferably 100 mol%, with respect to 100 mol% of the total of ethyleneimine and other monomers.

[0050] There are no particular restrictions on the other monomers mentioned above, but examples include alkyleneimines other than ethyleneimines, such as propyleneimine.

[0051] The polyethyleneimines and their chemically modified forms described herein are suitably used, for example, as various dispersants, cleaning agents, binders, adhesives, anchor coating agents, gas adsorbents, gas separation membranes, in the field of water purification, and as materials for antimicrobial polymers.

[0052] As stated above, the polyethyleneimines of this disclosure are exemplified as follows:

[12] A polyethyleneimine having a number average molecular weight of 500 or more and 5500 or less, a molecular weight distribution of 1.5 or more and 5.0 or less, and a ratio of the number of secondary amines to the number of secondary amines of polyethyleneimines having the same number average molecular weight obtained when ethyleneimine undergoes complete random polymerization of 1.35 or more and 1.78 or less.

[13] The polyethyleneimine according to

[12] , wherein the ratio of the number of secondary amines is preferably 1.37 or more and 1.76 or less, more preferably 1.39 or more and 1.74 or less, and even more preferably 1.55 or more and 1.74 or less.

[14] The polyethyleneimine according to

[12] or

[13] , wherein, when the number average molecular weight of polyethyleneimine is x, the number of secondary amines contained in the polyethyleneimine is 0.010344x or more, 0.010344x or more and 0.013638x or less, or 0.011809x or more and 0.013638x or less.

[15] The polyethyleneimine according to any one of

[12] to

[14] , wherein the number average molecular weight is preferably 500 to 5500, more preferably 600 to 5250, and even more preferably 700 to 5000.

[16] The polyethyleneimine according to any one of

[12] to

[15] , wherein the molecular weight distribution (Mw / Mn) is preferably 1.5 to 5.0, more preferably 1.7 to 4.8, and even more preferably 1.9 to 4.6.

[17] The polyethyleneimine according to any one of

[12] to

[16] , wherein the degree of branching is preferably 20% to 45%, more preferably 22% to 43%, and even more preferably 24% to 41%.

[18] The polyethyleneimine according to any one of

[12] to

[17] , wherein the ratio of secondary amine to 100 mol% of the total of primary amine, secondary amine, and tertiary amine contained in polyethyleneimine is preferably 46 mol% or more and 75 mol% or less, more preferably 48 mol% or more and 70 mol% or less, even more preferably 50 mol% or more and 60 mol% or less, and particularly preferably 51 mol% or more and 59 mol% or less.

[19] The polyethyleneimine according to any one of

[12] to

[18] , wherein the monomer composition is preferably 80 mol% to 100 mol%, more preferably 90 mol% to 100 mol%, even more preferably 95 mol% to 100 mol%, and particularly preferably 100 mol%, of ethyleneimine with respect to 100 mol% of the total of ethyleneimine and other monomers.

[20] Polyethyleneimine produced by any one of the methods of [1] to

[11] .

[21] Polyethyleneimine according to any one of

[12] to

[19] , produced by any one of the methods of [1] to

[11] .

[0053] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples, nor is it restricted by these examples.

[0054] [Evaluation Method] <Analysis of Average Molecular Weight> GPC was measured under the following conditions to determine the number-average molecular weight (Mn) and weight-average molecular weight (Mw) of polyethyleneimine. • Measuring device: Shimadzu Corporation • Column used: Resonaq SHODEX OHpak SB-807HQ (x2 columns) + SB-806M / HQ (x2 columns) • Eluent: 0.5 mol% sodium nitrate / 0.5 mol% acetic acid aqueous solution • Standard substance: Pullulan P-82 (Fujifilm Wako Pure Chemical Industries, Ltd.) • Detector: Differential refractometer (Shimadzu Corporation)

[0055] <Ratio of secondary amines (secondary amine ratio)> Dissolve 10% by mass of polyethyleneimine in heavy water containing 30% by mass of biacetic acid, 13 C-NMR (400 MHz) analysis was performed. More details are as follows: 13¹³C-NMR spectra were acquired using an Agilent VnmrJ instrument at a measurement frequency of 400 MHz. The sample consisted of 10% polyethyleneimine dissolved in heavy water containing 30% biacetic acid by mass. The analysis was performed under reverse gate decoupling conditions, at ambient temperature, without a reference substance. The spectral width was 25.1421 kHz, the acquisition time was 1.499 seconds, the relaxation delay was 0.501 seconds, the pulse width was approximately 45.0 degrees, and the transient count was 25,000. The secondary amine ratio was calculated using the integral values ​​of carbon atoms bonded to primary amines, carbon atoms bonded to secondary amines, and carbon atoms bonded to tertiary amines. For the assignment of peaks for each carbon atom, Macromolecules 2013, 46, 6891-6897 was consulted. Note that the secondary amine ratios used to calculate the number of secondary amines and the ratio of secondary amines are not expressed as percentages, that is, they are not multiplied by 100.

[0056] <Number of Secondary Amines> The number of secondary amines in polyethyleneimine can be calculated by dividing the number-average molecular weight obtained from the GPC analysis results by the molecular weight of ethyleneimine and multiplying the result by the secondary amine ratio. The general formula is as follows: (Number of secondary amines) = (Number-average molecular weight) / 43.07 × (Secondary amine ratio) When performing the above calculation, the values ​​of the number-average molecular weight and the secondary amine ratio were given with three significant figures.

[0057] <Ratio of Secondary Amines> The ratio of secondary amines was calculated using the following formula: (Ratio of secondary amines) = (Ratio of secondary amines) / 43.07 × 0.00773 When performing the above calculation, the value of the secondary amine ratio was calculated using a number with three significant figures, and the result was rounded down to the third decimal place after the calculation.

[0058] <Viscosity> A 50% by mass aqueous solution of polyethyleneimine, the target of evaluation, was prepared. The viscosity of polyethyleneimine as a 50% aqueous solution (viscosity of 50% aqueous solution) was measured using an E-type viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.) at a measurement temperature of 25°C, an arbitrary rotation speed adjusted within the measurable range, and a cone plate (1°34' × R24 cone rotor).

[0059] [Example 1] 8 g of a water-isopropyl alcohol (IPA) mixed solution (water:IPA mass ratio 1:1) was charged into a 40 mL pressure reactor as a solvent, 0.0389 g of 60% perchloric acid as a catalyst, and 0.2940 g of diethylenetriamine as an amine additive. 2 g of ethyleneimine was slowly added dropwise. The temperature was raised to 60°C, and ring-opening polymerization was carried out with stirring for 6 hours. The temperature was then further raised to 120°C and aged for 6 hours. After aging, the remaining ethyleneimine and solvent were removed at 100°C under reduced pressure to obtain the target polyethyleneimine. The obtained polyethyleneimine had a secondary amine ratio of 51%, a number-average molecular weight (Mn) of 750, a molecular weight distribution (Mw / Mn) of 2.1, and a viscosity of 140 mPa·s in a 50% aqueous solution. The polyethyleneimine contained 9 secondary amines, and the ratio of secondary amines was 1.53.

[0060] [Example 2] In a 40 mL pressure reactor, 4 g of a water-IPA mixed solution (water:IPA mass ratio 1:9) was added as the solvent, 0.0389 g of 60% perchloric acid was added as the catalyst, and 0.0502 g of ethylenediamine was added as the amine additive. 2 g of ethyleneimine was slowly added dropwise. The temperature was raised to 60°C, and ring-opening polymerization was carried out with stirring for 6 hours. The temperature was then further raised to 120°C and aged for 6 hours. After aging, the remaining ethyleneimine and solvent were removed at 100°C under reduced pressure to obtain the target polyethyleneimine. The obtained polyethyleneimine had a secondary amine ratio of 55%, a number-average molecular weight (Mn) of 1500, a molecular weight distribution (Mw / Mn) of 2.6, and a viscosity of 230 mPa·s in a 50% aqueous solution. The number of secondary amines contained in this polyethyleneimine was 19, and the ratio of secondary amines was 1.65.

[0061] [Example 3] In a 40 mL pressure reactor, 4 g of a water-IPA mixed solution (water:IPA mass ratio 1:1) was charged as the solvent, 0.0389 g of 60% perchloric acid was charged as the catalyst, and 0.0084 g of ethylenediamine was charged as the amine additive. 2 g of ethyleneimine was slowly added dropwise. The temperature was raised to 60°C, and ring-opening polymerization was carried out with stirring for 6 hours. The temperature was then further raised to 120°C and aged for 6 hours. After aging, the remaining ethyleneimine and solvent were removed at 100°C under reduced pressure to obtain the target polyethyleneimine. The obtained polyethyleneimine had a secondary amine ratio of 56%, a number-average molecular weight (Mn) of 3600, a molecular weight distribution (Mw / Mn) of 3.4, and a viscosity of 1180 mPa·s in a 50% aqueous solution. The number of secondary amines contained in this polyethyleneimine was 47, and the ratio of secondary amines was 1.68.

[0062] [Example 4] 4 g of a water-IPA mixed solution (water:IPA mass ratio 1:9) was charged into a 40 mL pressure reactor as a solvent, and 0.0083 g of ditrifluoromethanesulfonic anhydride was charged as a catalyst. 2 g of ethyleneimine was slowly added dropwise. The temperature was raised to 60°C, and ring-opening polymerization was carried out with stirring for 6 hours. The temperature was then further raised to 120°C and aged for 6 hours. After aging, the remaining ethyleneimine and solvent were removed at 100°C under reduced pressure to obtain the target polyethyleneimine. The obtained polyethyleneimine had a secondary amine ratio of 59%, a number-average molecular weight (Mn) of 2600, a molecular weight distribution (Mw / Mn) of 3.2, and a viscosity of 760 mPa·s in a 50% aqueous solution. The number of secondary amines contained in this polyethyleneimine was 36, and the ratio of secondary amines was 1.77.

[0063] [Reference Manufacturing Example 1] In a 40 mL pressure reactor, 4 g of pure water was charged as the solvent, 0.0389 g of 60% perchloric acid as the catalyst, and 0.0671 g of diethylenetriamine as the amine additive. 2 g of ethyleneimine was slowly added dropwise. The temperature was raised to 60°C, and ring-opening polymerization was carried out with stirring for 6 hours. The temperature was then further raised to 120°C and aged for 6 hours. After aging, the remaining ethyleneimine and solvent were removed at 100°C under reduced pressure to obtain the target polyethyleneimine. The obtained polyethyleneimine had a secondary amine ratio of 51%, a number-average molecular weight (Mn) of 1200, a molecular weight distribution (Mw / Mn) of 2.8, and a viscosity of 220 mPa·s in a 50% aqueous solution. The number of secondary amines contained in this polyethyleneimine was 14, and the ratio of secondary amines was 1.53.

[0064] [Reference Manufacturing Example 2] In a 40 mL pressure reactor, 4 g of pure water was charged as the solvent, 0.0083 g of ditrifluoromethanesulfonic anhydride as the catalyst, and 0.0335 g of ethylenediamine as the amine additive. 2 g of ethyleneimine was slowly added dropwise. The temperature was raised to 60°C, and ring-opening polymerization was carried out with stirring for 6 hours. The temperature was then further raised to 120°C and aged for 6 hours. After aging, the remaining ethyleneimine and solvent were removed at 100°C under reduced pressure to obtain the target polyethyleneimine. The obtained polyethyleneimine had a secondary amine ratio of 51%, a number-average molecular weight (Mn) of 2100, a molecular weight distribution (Mw / Mn) of 3.7, and a viscosity of 50% aqueous solution of 510 mPa·s. The number of secondary amines contained in this polyethyleneimine was 25, and the ratio of secondary amines was 1.53.

[0065] [Reference Manufacturing Example 3] 4 g of pure water was charged into a 40 mL pressure reactor as a solvent, and 0.0389 g of 60% perchloric acid was charged as a catalyst. 2 g of ethyleneimine was slowly added dropwise. The temperature was raised to 60°C, and ring-opening polymerization was carried out with stirring for 6 hours. The temperature was then further raised to 120°C and aged for 6 hours. After aging, the remaining ethyleneimine and solvent were removed at 100°C under reduced pressure to obtain the target polyethyleneimine. The obtained polyethyleneimine had a secondary amine ratio of 50%, a number-average molecular weight (Mn) of 3900, a molecular weight distribution (Mw / Mn) of 4.1, and a viscosity of 1350 mPa·s in a 50% aqueous solution. The number of secondary amines contained in this polyethyleneimine was 45, and the ratio of secondary amines was 1.50.

[0066] [Comparative Example 1] 4 g of pure water as solvent, 0.0083 g of ditrifluoromethanesulfonic anhydride as catalyst, and 0.1530 g of diethylenetriamine as amine additive were charged into a 40 mL pressure reactor. After the temperature was raised to 0-5°C, 2 g of ethyleneimine was slowly added dropwise. The mixture was stirred for 6 hours while maintaining low temperature conditions to allow ring-opening polymerization. The remaining ethyleneimine and solvent were removed at 80°C under reduced pressure to obtain the target polyethyleneimine. The obtained polyethyleneimine had a secondary amine ratio of 66%, a number-average molecular weight (Mn) of 1300, and a molecular weight distribution (Mw / Mn) of 2.5. The polyethyleneimine contained 20 secondary amines, and the ratio of secondary amines was 1.98.

[0067] [Comparative Example 2] In a 40 mL pressure reactor, 4 g of pure water was charged as the solvent, 0.0081 g of bis(trifluoromethylsulfonyl)amine as the catalyst, and 0.0601 g of diethylenetriamine as the amine additive. After the temperature was raised to 0-5°C, 2 g of ethyleneimine was slowly added dropwise. The mixture was stirred for 6 hours while maintaining the low temperature conditions to allow ring-opening polymerization. The remaining ethyleneimine and solvent were removed at 80°C under reduced pressure to obtain the target polyethyleneimine. The obtained polyethyleneimine had a secondary amine ratio of 69%, a number-average molecular weight (Mn) of 3600, and a molecular weight distribution (Mw / Mn) of 4.0. The polyethyleneimine contained 58 secondary amines, and the ratio of secondary amines was 2.07.

[0068] [Comparative Example 3] 0.0282 g of 36% by mass hydrochloric acid was charged into a 40 mL pressure reactor as a catalyst, and 0.0837 g of ethylenediamine was charged as an amine additive. The temperature was then raised to 120°C. Subsequently, 2 g of ethyleneimine was added. After the addition was complete and 95% of the ethyleneimine had reacted, the reaction solution was aged at 120°C for 2 hours to obtain the target polyethyleneimine. The obtained polyethyleneimine had a secondary amine ratio of 35%, a number-average molecular weight (Mn) of 1100, a molecular weight distribution (Mw / Mn) of 1.5, and a viscosity of 300 mPa·s in a 50% aqueous solution. The number of secondary amines contained in this polyethyleneimine was 9, and the ratio of secondary amines was 1.05.

[0069] [Comparative Example 4] 0.0282 g of 36% by mass hydrochloric acid was charged into a 40 mL pressure reactor as a catalyst, and 0.0177 g of ethylenediamine was charged as an amine additive. The temperature was then raised to 120°C. Subsequently, 2 g of ethyleneimine was added. After the addition was complete and 95% of the ethyleneimine had reacted, the reaction solution was aged at 120°C for 2 hours to obtain the target polyethyleneimine. The obtained polyethyleneimine had a secondary amine ratio of 37%, a number-average molecular weight (Mn) of 2800, a molecular weight distribution (Mw / Mn) of 1.5, and a viscosity of 1310 mPa·s in a 50% aqueous solution. The number of secondary amines contained in this polyethyleneimine was 24, and the ratio of secondary amines was 1.11.

[0070] [Comparative Example 5] 0.0282 g of 36% by mass hydrochloric acid was charged into a 40 mL pressure reactor as a catalyst, and 0.0096 g of ethylenediamine was charged as an amine additive. The temperature was then raised to 120°C. Subsequently, 2 g of ethyleneimine was added. After the addition was complete and 95% of the ethyleneimine had reacted, the reaction solution was aged at 120°C for 2 hours to obtain the target polyethyleneimine. The obtained polyethyleneimine had a secondary amine ratio of 36%, a number-average molecular weight (Mn) of 4500, a molecular weight distribution (Mw / Mn) of 1.6, and a viscosity of 2200 mPa·s in a 50% aqueous solution. The number of secondary amines contained in this polyethyleneimine was 38, and the ratio of secondary amines was 1.08.

[0071] From the results above, it has become clear that the manufacturing method disclosed herein makes it possible to efficiently produce polyethyleneimine with a high secondary amine (secondary amino group) content even under relatively mild conditions, without employing excessive cooling conditions.

[0072] Comparative Examples 3 to 5 are examples in which ethyleneimine underwent an almost uniform addition reaction with primary and secondary amines (in which ethyleneimine underwent substantially complete random polymerization).

Claims

1. A method for producing polyethyleneimine, comprising a polymerization step of polymerizing ethyleneimine at a temperature of 30°C or higher in the presence of a superacid, wherein the polymerization step is carried out using an alcohol / water mixed solvent.

2. A polyethyleneimine having a number-average molecular weight of 500 or more and 5500 or less, a molecular weight distribution of 1.5 or more and 5.0 or less, and a ratio of the number of secondary amines to the number of secondary amines of polyethyleneimines having the same number-average molecular weight obtained when ethyleneimine undergoes complete random polymerization of ethyleneimine, which is 1.35 or more and 1.78 or less.

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