JP2001122916A - Method for producing water-soluble polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a water-soluble polymer having a high-molecular weight, excellent water solubility and a low content of remaining monomer. SOLUTION: In this method for producing the high-molecular weight water-soluble polymer by irradiating a vinyl-based monomer with light rays, the method for producing the water-soluble polymer is characterized by using both a compound (A) containing a cycloalkanol structure in the molecule and an azo compound (B) as a photoinitiator. An especially preferable example as a component (A) is 1-benzoyl-2-hydroxycyclohexane. An especially preferable example as the component (B) is an azo compound having <=90 deg.C temperature of half-life of 10 hours. Acrylamide only or a monomer mixture containing >=10 mol% acrylamide is preferable as the vinyl-based monomer. A cationic monomer containxng >=5 mol% of one or more kinds of tertiary and quaternary salts of dimethylaminoethyl (meth)acrylate is preferably as the vinyl-based monomer to be used with acrylamide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a water-soluble polymer, and more particularly to a method for producing a water-soluble polymer by irradiating an aqueous solution of a vinyl monomer containing a specific photoinitiator with light. The present invention relates to a manufacturing method for obtaining coalescence. According to the method for producing a water-soluble polymer using the specific photoinitiator according to the present invention, a polymer having a high molecular weight and good solubility, and particularly having a reduced residual monomer content, such as a polymer flocculant Thus, a water-soluble polymer suitable for the above application can be obtained.

[0002] Water-soluble polymers are widely used as polymer flocculants used for the purpose of flocculating and suspending suspended substances in liquids such as wastewater, as well as papermaking chemicals and thickeners. However, in all applications, it is necessary that the molecular weight of the water-soluble polymer is high, the solubility is good, and the residual monomer is small. For example, in the use of a flocculant, when the molecular weight is low, the flocculation performance is deteriorated, and when the water solubility is poor, the dissolved pure component is reduced and the flocculation performance is deteriorated. In papermaking applications, if the molecular weight is not high, the yield of the paper is low, and poor water solubility causes unevenness in the quality of the paper surface and roughness. In thickener applications, if the molecular weight is low, the thickening effect decreases, and if the water solubility is poor, it is difficult to obtain a uniform thickening effect, which is inconvenient in appearance. If there are many residual monomers, safety points for workers handling water-soluble polymers in any applications,
For example, there is a danger due to skin irritation, etc.

[0003]

2. Description of the Related Art Conventionally, as a method for reducing the content of residual monomers, a method using a specific photoinitiator and a method devising a device and conditions for a light irradiation step are known. For example, JP-A-57-115409 discloses a method for producing a water-soluble high-molecular-weight polymer, which comprises benzyldimethylketal as a photoinitiator. However, the polymer obtained by this method is insufficient in solubility because the crosslinking reaction is likely to occur, and is not satisfactory in terms of reducing the residual monomer content.

On the other hand, JP-A-63-295604 and JP-A-63-309501 disclose polymerization starting with light having a specific irradiation intensity in the first stage, and then in the second stage starting from the first stage. A specific light irradiation method such as irradiation with light having a high irradiation intensity is disclosed. Although these methods have some residual monomer reduction effect, they cannot be said to be sufficient, and there is a problem that it is difficult to obtain a high molecular weight polymer. JP 11
Japanese Patent Publication No. 35612 discloses a method of performing light irradiation polymerization while gradually increasing the light intensity in the second and subsequent post-irradiations, but it is not preferable because the apparatus and operation become complicated.

Further, JP-A-10-279615 and JP-A-10-298215 disclose that the first stage is irradiated with light not containing a specific wavelength, and then the second and subsequent stages are irradiated with light containing the wavelength. A way to do that has been proposed. However, in these methods, light that does not include a specific wavelength needs to be substantially passed through filters, which not only complicates the apparatus but also wastes light energy, and the filters are extremely absorbed by the light energy. Overheating and, in some cases, there is a risk of fire.

Among the prior arts other than the above, those using an azo compound as a photoinitiator used for producing a water-soluble polymer have been known for a long time.
Japanese Patent Publication No. 22544 and Japanese Patent Publication No. 57-19121 disclose photopolymerization methods using an azo compound having a specific composition as a photoinitiator, but in any of these methods, it is difficult to obtain a high molecular weight polymer. It was not satisfactory for use as a flocculant. In addition, Japanese Patent Publication No. 4-57682 and Japanese Patent Publication No. 7-10895 disclose a method in which a specific photoinitiator such as a benzoin derivative is used in combination with an azo-based photoinitiator. The polymer was not sufficiently soluble because the crosslinking reaction was liable to occur, and the polymer was insufficient in reducing the residual monomer. Further, in Japanese Patent Application No. Hei 11-084952, the present inventors have proposed a compound having a cycloalkanol structure as a photoinitiator used for producing a water-soluble polymer. Although both degree of solubility and solubility can be achieved, they have not been sufficiently satisfactory in terms of reducing the residual monomer content.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a process for producing a water-soluble polymer having a high molecular weight, good solubility in water, and a low residual monomer content.

[0008]

Means for Solving the Problems In the production method of obtaining a water-soluble polymer having a high molecular weight by irradiating an aqueous solution of a vinyl monomer with light, the present inventors have specified two kinds of compounds as photoinitiators. By using together, the crosslinking reaction during the photoradical polymerization is suppressed, the insoluble content is small while having a high molecular weight, and the residual monomer content is low, such as a polymer flocculant, a papermaking drug, a thickener, etc. It has been found that a water-soluble polymer suitable for the use of the above can be obtained.

That is, in the present invention, the method for producing a water-soluble polymer according to the first invention comprises producing a high-molecular-weight water-soluble polymer by irradiating an aqueous solution of a vinyl monomer containing a photoinitiator with light. A method comprising using a compound (A) having a cycloalkanol structure in a molecule and an azo compound (B) in combination as a photoinitiator.

The photoinitiator (A) used in the present invention is preferably 1-benzoyl-1-hydroxycyclohexane as in the second invention.

A particularly preferred compound as the photoinitiator (B) is an azo compound having a 10-hour half-life temperature of 90 ° C. or less as in the third invention.

The vinyl monomer used in the present invention is, as in the fourth invention, preferably acrylamide alone or a monomer mixture containing 10 mol% or more of acrylamide. in this case,
The vinyl monomer or monomer mixture used in combination with acrylamide as in the fifth invention is one or more cationic monomers of tertiary and quaternary salts of dimethylaminoethyl (meth) acrylate Particularly preferred are cationic monomers and cationic monomer mixtures containing at least 5 mol%.

According to a sixth aspect of the present invention, in the method for producing a water-soluble polymer according to the first to fifth aspects, light having a wavelength of 300 to 400 nm is used for an aqueous monomer solution having a liquid depth of 50 mm or more. After irradiating with the irradiation intensity in the range of 0.5 to 100 W / m ² in the first stage, and further irradiating for 10 minutes or more in the second stage, light irradiation is performed so that the light amount becomes 70,000 J / m ² or more. This is a manufacturing method for performing.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. (1) Photoinitiator In the method for producing a water-soluble polymer of the present invention, a compound (A) having a cycloalkanol structure in a molecule and an azo compound (B) are used in combination as a photoinitiator. The compound (A) is a compound having an alicyclic secondary alcohol formed by substituting one hydrogen atom of a cycloalkane with a hydroxyl group, and is a compound represented by the following structural formula (1). Is preferred.

[0015]

Embedded image

[In the above formula (1), X is A
r—C (＝ O) — or Cy—N ＝ N— and Ar
Is a phenyl group or -Cl, -Br, -OH, -Alk
Or -OAlk (where Alk has 1 to 1 carbon atoms)
6 represents an alkyl group), Cy is a group represented by a structural formula represented by the following formula (2), and Y and Z are -OH, -N (A
lk) ₂ , -OAlk, -O-Si (Alk) ₃ or-
CN, R ¹ and R ³ are —H, —OH, or an alkyl group having 1 to 6 carbon atoms, and R ² and R ⁴ are —H
Or an alkyl group having 1 to 6 carbon atoms, wherein Y is -O
When H, a is an integer of 0 to 11, b is an integer of 1 to 11, and when Y is not -OH, a and b are 1 to 1.
Is an integer of 1, and a + b is an integer of 2 to 11, and when Z is -OH, c is an integer of 0 to 11, d is an integer of 1 to 11, and Z is not -OH. And c and d are integers of 1 to 11, and c + d is 2 to 11
Is an integer.

[0017]

Embedded image

Particularly preferred as the compound (A) is a compound represented by the structural formula (1)
There Ar-C (= O), Y is -OH, a is is 0, b is 4 or 5, R ¹ and R ² is a compound that is -H.

Furthermore, among the above-mentioned compounds (A) in the present invention, it is difficult to form a crosslink, a polymer having a high degree of polymerization and excellent in solubility is easily obtained, and it is commercially available as an inexpensive general-purpose compound. Particularly preferred in this regard is 1
—Benzoyl-1-hydroxycyclohexane.

On the other hand, as the azo compound (B) used in the production method of the present invention, any azo compound which generates a radical by light irradiation and has a function as a polymerization initiator can be used. Specific azo-based photoinitiators include, for example, 2,2′-azobis (2-methylpropionic acid), 2,2′-azobis (2-ethyl-4-methoxyvaleric acid), 2,2′-azobis [ 2- (2-chlorocyclohexyl) lauric acid], 2,2'-azobis (2-
Phenylacetic acid), 2,2'-azobis [2- (3-hydroxyphenyl) butyric acid], 2,2'-azobis [2-
(4-aminophenethyl) isovaleric acid] and free acids such as 4,4'-azobis (4-cyanovaleric acid)
i, Na, K, Fe, Al, NH ₄ , Mg, Ca, Ba
And the like.

Further, 2,2'-azobis (2-amidinopropane), 2,2'-azobis (2-N-phenylaminoamidinopropane), 1,1'-azobis (1-amidino-1-cyclopropylethane) ), 2,2′-azobis (2-amidino-4-methylpentane), 2,2 ′
-Azobis- (N, N'-dimethyleneisobutylamidine), 2,2'-azobis (1-iminor 2-methyl-1-phenylhydrazinopropane), 1,1'-azobis (1-amidino-1-cyclohexylethane) , 2,
2'-azobis (1-imino-1-ethylamino-2-
Methylpropane), 2,2′-azobis (1-allylamino-1-iminor 2-methylbutane), 2,2′-azobis (1-iminor 1-cyclohexylamino-2-)
Cyclohexylpropane), 2,2′-azobis (1-
Imino 1-laurylamino-2-ethylpropane),
2,2′-azobis (1-iminor 1-phenylamino-2,4-dimethylpentane), 2,2′-azobis (1-iminor 1-benzylamino-2-cyclopentylpropane), 2,2′-azobis (1-Iminnow 1-
Parachlorobenzylamino-2-methylbutane), 2,
Compounds such as 2'-azobis (2-cyclohexylpropionic acid hydrazide), 2,2'-azobisisobutyric acid hydrazide, and mineral salts thereof.

Further, 2,2'-azobis (2-carbamoylpropane), 2,2'-azobis [2- (N-ethylcarbamoyl) propane], 2,2'-azobis (2
-Methyl-N-propylbutyric acid amide), 2,2'-azobis (N-methyl-2-cyclopropylpropionic acid amide), azodisulfonic acid, azobis (methanesulfonic acid), azobis (α-methylbutyronitrile) 4-sulfonic acid), azobis (α-methyl-β-ethoxycarbonylbutyronitrile 4-sulfonic acid), 4,4′-
Compounds such as azobis-4-cyanovaleric acid, 2,2′-azobis (2-methylpropionic acid), 3,3′-azobis (3-cyanobutyric acid), and 4,4′-azobis (4-cyanolepric acid) These are their salts.

Further, 2- (carbamoylazo) isobutyronitrile, 2,2'-azobis (isobutylamide) and its hydrate, 2,2'-azobis [2-methyl-N- (2-hydroxy Ethyl) propionamide], 2,2'-azobis [2-methyl-N- (1,1
-Bis (hydroxymethyl) ethyl) propionamide], 2,2'-azobis [2-methyl-N- (1,1
-Bis (hydroxymethyl) -2-hydroxyethyl)
And propionamide].

Among these azo compounds, an azo compound having a 10-hour half-life temperature of 90 ° C. or less is preferable since it has an advantage that a residual monomer in a polymer obtained after light irradiation is small. Specific preferred azo compounds having a 10-hour half-life temperature of 90 ° C. or less include 2,2.
2′-azobis (2-amidinopropane) hydrochloride, 4,
4'-azobis (4-cyanovaleric acid), 2,2'-azobis [N- (2-carboxyethyl) -2-methylpropionamidine], dimethyl 2,2'-azobisisobutyrate, 2,2 Azobisisobutyronitrile, 2,
2′-azobis (2,4-dimethylvaleronitrile),
2,2′-azobis (2-methylbutyronitrile),
1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis {2-methyl-N- [2-
(1-hydroxybutyl)] propionamide {, 2,
2′-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], 2,2′-azobis [2
-(5-methyl-2-imidazolin-2-yl) propane] hydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] hydrochloride, 2,2'-azobis [2- (2 -Imidazolin-2-yl) propane] sulfate, 2,2'-azobis [2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane] hydrochloride,
2,2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} hydrochloride and 2,2'-azobis [2- (2-imidazolin-2-yl) propane] Etc.

The compounding ratio of the compound (A) having a cycloalkanol structure in the molecule and the azo compound (B) used together as a photoinitiator in the present invention is (A) /
[(A) + (B)] (weight ratio) is preferably 1/300 to 1/2, and more preferably 1/100 to 1/3. When the above ratio is less than 1/300, the effect of the compound (A) is small, so that crosslinking is likely to occur, and the solubility of the obtained polymer tends to be impaired. On the other hand, when the above ratio is more than 1/2, the effect of the compound (B) is too weak and the amount of the residual monomer tends to increase.

(2) Vinyl Monomer As the vinyl monomer (hereinafter sometimes simply referred to as “monomer”) used in the present invention, a water-soluble monomer is preferable. Acrylamide, (meth) acrylic acid and alkali metal salts or ammonium salts such as sodium salts of these acids, acrylamidoalkanesulfonic acid such as acrylamido-2-methylpropanesulfonic acid and alkali metal salts or ammonium salts thereof, dimethylaminoethyl ( Dialkylaminoalkyl (meth) acrylates such as (meth) acrylate;
Tertiary or quaternary salts such as hydrochlorides and sulfates thereof,
And tertiary or quaternary salts such as N, N'-dialkylaminoalkyl (meth) acrylamide and their hydrochlorides and sulfates, and dialkyldiallylammonium salts such as dimethyldiallylammonium chloride. Further, a water-insoluble monomer such as acrylonitrile, an N-substituted derivative of acrylamide, or styrene may be used in combination with the water-soluble monomer as long as the water-soluble property of the obtained polymer is not impaired. These monomers may be used alone or in a combination of two or more. In this specification, acrylamide or methacrylamide is represented as (meth) acrylamide, acrylic acid or methacrylic acid is represented as (meth) acrylic acid, and acrylate or methacrylate is represented as (meth) acrylate.

The vinyl monomer used in the present invention may be composed of acrylamide alone, or 10 mol% or more (more preferably 15 mol% or more) of acrylamide or a mixture thereof. A monomer mixture comprising another polymerizable vinyl monomer is preferred. In this case, the other vinyl monomer is preferably a tertiary salt and / or quaternary salt of dialkylaminoalkyl (meth) acrylate, and among them, a tertiary salt and / or tertiary salt of dimethylaminoethyl (meth) acrylate is preferable. Grade salts are particularly preferred. Further, one or two or more tertiary and quaternary salts of acrylamide (more than 10 mol% and dimethylaminoethyl (meth) acrylate) (the total concentration thereof is preferably 5 mol% or more, more preferably 10 mol% or more) and A monomer mixture comprising another vinyl monomer other than these is also a particularly preferred vinyl monomer in the present invention.

(3) Method for Producing Water-Soluble Polymer The above-mentioned vinyl-based monomer and an aqueous solution containing two specific photoinitiators are polymerized by irradiating them with light to obtain a high-molecular-weight insoluble polymer. And a water-soluble polymer having an extremely low content of residual monomer and particularly low residual monomer content.
In the present invention, a specific method of irradiating a compound (A) having a cycloalkanol structure in a molecule and an azo compound (B) to a vinyl monomer aqueous solution containing a photoinitiator as light is particularly limited. However, it can be carried out by a general photopolymerization method. In the production method of the present invention, the monomer aqueous solution can be polymerized in a batch manner by irradiating the monomer aqueous solution in a container and irradiating the monomer aqueous solution. Can be continuously supplied and irradiated with light. The monomer concentration in the aqueous monomer solution is usually preferably in the range of 20 to 90% by weight, and more preferably in the range of 25 to 80% by weight. If the monomer concentration exceeds 90% by weight, it is difficult to remove the heat of polymerization, and it becomes difficult to control the polymerization reaction. On the other hand, when the monomer concentration is less than 20% by weight, the productivity and the drying efficiency in the case of forming a powdery product are low.

The concentration of the photoinitiator is determined in consideration of the molecular weight and composition of the water-soluble polymer to be obtained, but usually, the concentration of the compound (A) is based on the weight of the monomer. 1 to 1,000 ppm is preferable on the basis, more preferably 2 to 500 ppm, and still more preferably 3 to 200 pp.
m. The concentration of the compound (B) is preferably from 10 to 10,000 ppm, more preferably from 20 to 5,000 ppm, still more preferably from 3 to 10 ppm by weight based on the monomer.
0 to 2,000 ppm. Light sources include fluorescent chemical lamps, fluorescent blue lamps, metal halide lamps,
High-pressure mercury lamps, low-pressure mercury lamps, and the like can be used, and ultraviolet light and visible light obtained from these light sources can be used. However, the use of a light source that selectively includes a wavelength of 300 to 400 nm can be used as a photoinitiator. Is preferred in that it works efficiently. The intensity of the light irradiation is determined in consideration of the initiator concentration, the molecular weight of the water-soluble polymer to be obtained, the polymerization time, and the like.
It is preferably in the range of W / m ² . The irradiation intensity may be constant during the polymerization or may be changed during the polymerization. The irradiation intensity of the second stage is usually 50 to 2,000 W / m.
2 can be used. The light irradiation time (residence time in the case of the continuous type) is usually 0.5 to 120 in the first stage.
Minutes, preferably 3 to 90 minutes, more preferably 5 to 90 minutes.
It is 60 minutes, and in the second stage, it is preferably 10 minutes or more, more preferably 10 to 60 minutes, and particularly preferably 10 to 30 minutes.

The preferred temperature of the reaction system at the start of the polymerization is 40 ° C. or lower, preferably 25 ° C. or lower, more preferably 15 ° C. or lower. When the polymerization initiation temperature is higher than 40 ° C., the frequency of the branching reaction may increase to increase the amount of insolubles or the average molecular weight may decrease. Although the lower limit of the polymerization initiation temperature is not particularly limited, it is preferably −10 ° C. or higher from the viewpoint of operability and energy efficiency. Further, the maximum temperature reached in the system during the polymerization is preferably less than 100 ° C, more preferably less than 95 ° C. In this solution polymerization method, in order to reduce the content of the residual monomer, a light having a wavelength of 300 to 400 nm is selected, and then a deep liquid is added to a monomer aqueous solution of 50 mm or more.
It is preferable to perform the irradiation by light irradiation in two stages. First, in the first stage, the irradiation intensity is 0.5 to 10
Light in the range of 0 W / m ² is irradiated until the polymerization is substantially completed. Whether or not the polymerization is completed is confirmed by stopping the rise in the liquid temperature due to the heat of polymerization. The irradiation conditions in the second stage to be continuously performed include the second condition.
It is preferable to perform irradiation for 10 minutes or more so that the light amount at the stage becomes 70,000 J / m ² or more. The depth of the aqueous solution, that is, the liquid depth, affects photopolymerization and productivity. If the liquid depth is less than 50 mm, the productivity is low, which is not preferable.

The molecular weight of the water-soluble polymer obtained by the production method of the present invention is a viscosity of 0.5% by weight in a 4% by weight aqueous sodium chloride solution at 25 ° C. (a value measured by a B-type viscometer. , Which is also referred to as “0.5% salt viscosity”), and the numerical value is preferably 10 mPa · S or more, more preferably 30 mPa · S or more. When such a high-molecular-weight water-soluble polymer is used as a polymer flocculant, excellent flocculation performance can be exhibited by adding a small amount to wastewater or sludge.
The upper limit of the 0.5% salt viscosity is not particularly limited, but is usually 2%.
00 mPa · s or less. The water-soluble polymer obtained by the production method of the present invention was prepared by dissolving a polymer sample in ion-exchanged water to prepare 400 ml of a 0.1% by weight polymer solution. When filtered through, the volume of the insoluble matter remaining on the sieve is preferably 5% by volume or less based on the total amount of the solution,
The content is more preferably 1% by volume or less, and most preferably no insoluble content. According to the present invention, even in the case of the high molecular weight as described above, almost no insoluble matter is generated, it is economical with no loss of monomer, and the insoluble matter is clogged in a pipe or the like. As a result, stable operation is possible when the product is used.

In the production method of the present invention, other initiators such as benzophenone, benzoin, benzoin alkyl ether, acetophenone, and the like may be used as the photoinitiator in addition to the compounds (A) and (B).
Even when a photoinitiator such as an acylphosphine oxide type, a photosensitizer such as an amine type such as triethanolamine or methyldiethanolamine, a thermal polymerization initiator such as a persulfate or a peroxide, or a redox initiator is used in combination. Good.

The steps of drying and pulverizing the polymer obtained by the above-mentioned production method may be carried out according to a conventional method. The water-soluble polymer obtained by the present invention can be used for various applications, specifically, a polymer flocculant,
Examples thereof include a papermaking agent and a thickener, and in particular, can be suitably used as a polymer flocculant.

[0034]

The present invention will be described more specifically with reference to the following examples. (Example 1) A monomer mixture of 75 mol% of acrylamide and 25 mol% of a quaternized salt of dimethylaminoethyl acrylate with methyl chloride (hereinafter referred to as "DAC") was 850 g in total weight and had a monomer concentration of 35 mol%. Distilled water was added to give a weight percent. This was charged into a cylindrical glass container (reactor) having an inner diameter of 146 mm, the pH was adjusted to 4.0, and nitrogen bubbling was performed for 30 minutes while maintaining the temperature of the aqueous solution at 10 ° C to obtain an aqueous monomer solution. At this time, the liquid depth is 5
5 mm. Next, 1-benzoyl-1-hydroxycyclohexane (compound (A)) as a photoinitiator was added to this aqueous monomer solution on a weight basis with respect to the monomer pure content.
40 ppm and 2,2′-azobis (2-amidinopropane) hydrochloride (10 hour half-life temperature = 56 ° C.) 600
ppm was added and nitrogen was bubbled for an additional 2 minutes. Then, from above the reactor, a 100 W black light (trade name “H100BL” manufactured by Toshiba Corporation; center wavelength: 3)
65 nm. ) At a radiation intensity of 16 W / m ² for 20 minutes (the first stage light amount of 19,200 J /
m ² ). Then, go to the second stage, 116W / m ²
For 30 minutes (irradiation intensity of the second stage is 209,
000 J / m ² ) to obtain a hydrogel polymer. This hydrogel was cut into chunks having a particle size of about 3 mm, dried at 80 ° C. for 5 hours with a hot air drier, and then pulverized with a pulverizer to obtain a powdery polymer. When the obtained polymer was added to sewage sludge and tested for its effect as a flocculant, a good floc was formed, and the sludge after the floc formation was excellent in filterability. The resulting cake had a low moisture content.

(Example 2) In Example 1, instead of 2,2'-azobis (2-amidinopropane) hydrochloride as the compound (B) as a photoinitiator, 4,4'-azobis (4- (Cyanovaleric acid) (10-hour half-life temperature = 69)
(C) A powdery polymer was obtained in the same manner as in Example 1 except that 600 ppm was added. When the obtained polymer was added to sewage sludge and tested for its effect as a flocculant, a good floc was formed, and the sludge after the floc formation was excellent in filterability. The resulting cake is
The water content was low.

(Comparative Example 1) In Example 1, the compound (B) was not added as a photoinitiator, but 1-benzoyl-1-
A powdery polymer was obtained in the same manner as in Example 1, except that only hydroxycyclohexane (compound (A)) was added in an amount of 40 ppm by weight based on the monomer pure content.

Comparative Example 2 A powdery polymer was prepared in the same manner as in Example 1 except that 1-benzoyl-1-hydroxycyclohexane was not added as a photoinitiator. Obtained.

The following physical properties of the polymers obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were measured, and the results are shown in Table 1. (Measurement Method of Physical Properties) <0.5% Salt Viscosity> Each polymer was dissolved in a 4% by weight aqueous sodium chloride solution to prepare a 0.5% by weight polymer solution, which was then measured at 25 ° C. using a B-type viscometer. After 5 minutes, the viscosity was measured under the conditions of 60 rpm. <Insoluble content> Each polymer was dissolved in ion-exchanged water to obtain 0.1%.
A 400% by weight polymer solution was prepared, and the whole solution was filtered through a 20-cm diameter, 83-mesh sieve.
The insoluble material remaining on the sieve was collected and its volume was measured. <Amount of residual monomer> 2.0 g of each polymer was 80/20 vo.
The mixture was added to 20 ml of a 1% acetone / water mixed solvent and allowed to stand for 16 hours or more to perform extraction. The supernatant liquid after the extraction was collected, and the amount of residual monomer was measured by gas chromatography.

[0039]

[Table 1]

As can be seen from the results in Table 1, the polymers of Examples 1 and 2 produced according to the method for producing the polymer according to the present invention have a high 0.5% salt viscosity of 90 mPa · S or more. High molecular weight is shown. Further, it was a water-soluble polymer containing no insoluble content and having a very low residual monomer content of 0.2% by weight or less. On the other hand, in Comparative Example 1 in which only the compound (A) was used as the photoinitiator, the content was 0.1%.
Although the 5% salt concentration is high and the molecular weight is high and does not contain any insoluble components, the residual monomer concentration is 10 times or more as compared with Examples 1 and 2. On the other hand, in Comparative Example 2 in which only the compound (B) was used for polymerization, although the residual monomer was low, the insoluble content contained in the polymer was remarkably large at 70 ml, and the salt viscosity of Example 1 was 0.5%. It was clearly lower than 2.

It should be noted that the present invention is not limited to the specific embodiments described above, but can be variously modified within the scope of the present invention in accordance with the purpose and application.

[0042]

The method for producing the water-soluble polymer of the present invention is as follows:
It has the effect of suppressing the crosslinking reaction during photo-radical polymerization and promoting the reaction at a high polymerization reaction rate.
Since it is possible to obtain a polymer having a high molecular weight and a small amount of insoluble components and a reduced amount of residual monomers, it is possible to obtain a water-soluble polymer suitable for a wide range of uses, particularly for a polymer flocculant. is there.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor: Miho Miho 1Funamicho, Minato-ku, Nagoya-shi, Aichi F-term (reference) in Nagoya Research Laboratory, Toagosei Co., Ltd. 4J011 QA06 QA07 QA38 SA61 SA79 UA01 UA06 VA06 4J100 AL08Q AM15P BA31Q BA32Q CA01 CA04 FA03 FA41

Claims (6)

[Claims] 1. A method for producing a water-soluble polymer by irradiating an aqueous solution of a vinyl monomer containing a photoinitiator with light, wherein a compound (A) having a cycloalkanol structure in the molecule and an azo compound (B) A method for producing a water-soluble polymer, comprising using a photoinitiator comprising: 2. The method for producing a water-soluble polymer according to claim 1, wherein the photoinitiator (A) is 1-benzoyl-1-hydroxycyclohexane. 3. The photoinitiator (B) is an azo compound having a 10-hour half-life temperature of 90 ° C. or less.
A method for producing the water-soluble polymer according to the above. 4. The production of a water-soluble polymer according to claim 1, wherein the vinyl monomer is acrylamide alone or a monomer mixture containing acrylamide in an amount of 10 mol% or more. Method. 5. A vinyl monomer or monomer mixture used in combination with acrylamide, wherein one or two of a tertiary salt and a quaternary salt of dimethylaminoethyl (meth) acrylate are used.
5. The method for producing a water-soluble polymer according to claim 4, wherein the monomer is a cationic monomer containing at least 5 mol% of at least one species. 6. A monomer aqueous solution having a liquid depth of 50 mm or more,
Using light having a wavelength of 300 to 400 nm, first irradiation is performed at an irradiation intensity in the range of 0.5 to 100 W / m ² in the first step, and then irradiation for 10 minutes or more is performed in the second step at a light intensity of 70,
000J / m ² or more and a manufacturing method of the water-soluble polymer of claims 1 to 5, wherein performing the light irradiation so.