JPS62265302A - Production of water-soluble vinyl polymer - Google Patents

Abstract

PURPOSE:To obtain a high-MW vinyl polymer prominently excellent in water solubility, by photopolymerization using a polymerization initiator included in cyclodextrin. CONSTITUTION:A polymerization initiator (B) included in cyclodextrin is obtained by mixing a solution formed by dissolving cyclodextrin in, for example, an isopropyl alcohol/water mixed solvent with a polymerization initiator comprising a carboxyl compound including biacetyl, benzophenone, benzil, benzoin and cyclohexanone, agitating the mixture to form a homogeneous solution and completely evaporating the mixed solvent from the solution by heating with warm water in a vacuum. an aqueous solution of component B is added to an aqueous solution of a water-soluble monomer (A) such as acrylamide and agitated to form a homogeneous mixture. This solution is subjected to polymerization by irradiation with ultraviolet rays of wavelengths around 360nm to obtain the title polymer.

Description

[Detailed description of the invention] The present invention relates to a method for producing a water-soluble vinyl polymer.

More specifically, the present invention relates to a method for producing a water-soluble vinyl polymer by a photopolymerization method characterized by using a polymerization initiator encapsulated with cyclodextrin.

As one method of polymerizing an aqueous solution of a water-soluble vinyl monomer to obtain a water-soluble polymer, a so-called photopolymerization method has been proposed, which involves irradiation with wavelengths in the ultraviolet region. .

This photopolymerization method generally relies only on light irradiation, that is, direct photopolymerization is rare, and a polymerization initiator is often used in combination, and the use of a polymerization initiator is essential, especially in industrial applications. It is a requirement.

The type of polymerization initiator is usually selected by considering the type of water-soluble vinyl monomer to be targeted, the monomer concentration of the polymerization solution, the molecular weight of the target polymer, etc. The wavelength of the light beam used should also be selected with special consideration. The reason for this is that the polymerization initiator absorbs light of a specific wavelength, and due to its excitation, it decomposes into radicals, and then
In order to initiate polymerization, in other words, when irradiated with light rays of various wavelengths, by selectively absorbing only the rays of a certain wavelength, radical decomposition of the polymerization initiator occurs for the first time, and monomers are formed. This is because the polymerization of can result in F=(ability).

Therefore, when photopolymerization is carried out using an irradiation device that emits light of a certain wavelength, it is not permissible to select any type of polymerization initiator, but only the type of polymerization initiator that has an absorption band corresponding to the wavelength. Selection becomes extremely important.
By the way, in the photopolymerization of conventionally known water-soluble polymers, what is generally called near ultraviolet light, which has a wavelength of 300 nm to 400 nm, particularly around 360 nm, is often used. Because near ultraviolet rays have a center wavelength of 360 nm, they are safer to the naked eye than, for example, ultraviolet rays with wavelengths shorter than 300 nm. This comes from two reasons: the advantage of not having a negative impact on the naked eye of workers, and the fact that near-ultraviolet lamps are commercially available as chemical lamps at low prices.For example, Toshiba's chemical lamp FL40SBL, Phi 1ips' TLADK.
30W105. Matsushita Electric Works Plank Light Blue jj
j Light lamps, etc. Various polymerization initiators have been developed and used for these inexpensive commercially available near-UV pairs.

Among them, when the target of polymerization is a water-soluble polymer, it has traditionally been used as a polymerization initiator.

Generally, carbonyl compounds are used in Tingtong.1 For example, pentuphenone, which has an absorption maximum near 350 nm, azobisisobutyronitrile, which is often used under near ultraviolet irradiation, and carbonyl compounds such as benzoin, etc. Often used as a compound.

However, since they have general hydrophobicity in common,
This is extremely inconvenient in the case of water-soluble polymers, which have poor solubility in aqueous solvent systems and require dissolution of the polymerization initiator into a monomer polymerization solution using water as a solvent. In order to improve this problem, conventionally, a carbonyl compound as an initiator is dissolved in a polymerization solution in advance in a solvent such as various alcohols such as methanol, and then light irradiation is performed, or the hydrophilicity is increased by using a surfactant in combination. Emulsification and dispersion in a polymerization solution has been carried out at a high concentration.

However, the conventional method of dissolving a polymerization initiator in a water-soluble monomer has problems such as chain transfer due to the solvent used to dissolve the polymerization initiator, foaming due to the use of surfactants, and a decrease in the transparency of the polymerization solution. As a result, there are drawbacks such as a decrease in water solubility as a water-soluble type compound, as well as inhibiting an increase in molecular weight.

In order to solve these problems, the present inventors conducted intensive research and arrived at the present invention. That is, the present invention uses a polymerization initiator encapsulated with cyclodextrin.

The present invention provides a method for producing a water-soluble vinyl polymer by a photopolymerization method, characterized in that:

According to the present invention, when polymerizing a water-soluble polymer, the polymerization initiator is conjugated with cyclodextrin in advance, especially for the purpose of increasing the affinity of the carbonyl compound-based initiator and improving its solubility in water. , the hydrophilicity of the polymerization initiator is sufficiently increased to make it water-soluble, promoting uniform dispersion in the polymerization solution, thereby enabling uniform photopolymerization, and making it extremely water-soluble with high molecular weight. This method established an excellent method for producing water-soluble polymers.

In this way, when photopolymerization is carried out using a polymerization initiator encapsulated by cyclodextrin, it has been confirmed that cyclodextrin itself has no absorption in both the ultraviolet and visible light wavelength regions. Photodecomposition of a polymerization initiator that has become water-soluble due to inclusion is not inhibited by inclusion.

In addition, the water-soluble vinyl monomer used in the present invention includes:
For example, acrylamide, methacrylamide, acrylic acid, methacrylic acid, vinyl sulfonic acid, acrylamide-methylpropane sulfo/acid, itaconic acid, etc.
their salts, (meth)acrylic acid dialkylaminoalkyl esters, their salts, or acid salts;

Examples include quaternized products thereof, dialkylaminoalkylacrylamides, salts or acidic salts thereof, and quaternized products thereof, and these may be used alone or in combination of two or more kinds.

As the polymerization initiator used in the present invention, carbonyl compounds including biacetyl, benzophenone, benzyl, benzoin, and cyclohexane compounds are preferably selected.

The wavelength of ultraviolet rays used in the present invention is approximately 200 nm.
to 400nm, or 300nm to 40nm
It may be limited to a range of 0 nm.

According to the present invention, in the production of water-soluble polymers.

In particular, in place of the conventional method of dissolving a polymerization initiator made of a carbonyl compound in advance in an organic solvent and then dispersing it in a polymerization solution under near ultraviolet irradiation, the polymerization initiator made of a carbonyl compound is By incorporating a polymerization initiator, a hydrophobic substance can be improved in water solubility and become wood-philic, allowing it to be uniformly dissolved in a single polymerization solution and carrying out a uniform polymerization reaction. Furthermore, the present invention has made it possible to polymerize a water-soluble polymer having a much higher molecular weight and extremely superior water solubility than conventional techniques.

Next, one embodiment of the present invention will be specifically explained using examples.

Example 1 20.0 g of commercially available β-cyclodextrin [manufactured by Hanui Chemical Co., Ltd.] was mixed with isopropyl alcohol/wood = 50
wt, 7wt, % (7) After uniformly dissolving in 1,000 g of U mixed solvent, 4.5 g of benzoin isopropyl ether is mixed and stirred to uniformly dissolve. After stirring for about 1 hour, the mixed solvent is completely evaporated under vacuum while heating with hot water at 70° C. to obtain a white evaporated solid.

This powder has a molar ratio of β-cyclodextrin/benzoin isopropyl ether of approximately 1 mo 1/1 mo.
1. The weight ratio is estimated to be 4.5wt, %/1wt, % inclusions.

The finely powdered benzoin isopropyl ether conjugate obtained by grinding this in a mortar contains about 18%
0.111 g of benzoin isopropyl ether conjugate is collected. On the other hand, 600g of an acrylamide aqueous solution containing 20ml of sodium acrylate was prepared with a composition of 33.3%. After expulsion, benzoin isopropyl ether conjugate 0
．． Dissolve 111 g in 50 g of water in advance.

After degassing with nitrogen gas, the dissolved solution is mixed into the monomer solution,
Stir well. At this time, the concentration of benzoin propyl ether in 0.111 g of the benzoin isopropyl ether conjugate was 1100 pp of Zimmer's solution.

This polymerization solution was placed in a jacketed polymerization vessel with a glass lid that was previously filled with nitrogen gas, and the outside was heated with cooling water at 10°C, and a commercially available Toshiba Chemical Lamp F
L40SBLfi was irradiated with near-ultraviolet light centered at 360 nm, and after 30 minutes, the polymerization solution turned into a rubber-like elastic body. Take this out and grind it with a commercially available meat grinder to 1.0 mm to 2.
It was crushed into 0 mm pieces and dried with hot air at 70°C for 120 minutes.

A powdered acrylic acid/acrylamide co-merged powder having a water content of 80% was obtained.

The intrinsic viscosity of this powder was determined by A14 [η] = 30
．． It showed a surprisingly high value of 5 (d I/g) [1N-NaCl, 30°C], and when the water-insoluble content (%) was determined.

[Powder sample solid content - dissolved Water insoluble content (%) = □ Powder sample solid content g Sample solid content]g x 100=0.04(%) Very good water solubility was obtained.

Conventionally, under such polymerization conditions, [η]=20.
0 to 23, 0 (d l/g), water insoluble content (%) =
In view of the fact that values of about 0.11 to 0.25 (%) are commonly obtained, it is confirmed that the present invention is superior in each level as shown in Example 1.

Comparative Example 1 0.02g of benzine isopropyl ether alone without conjugation to β-cyclodextrin, 2.0g
The powdered acrylic ugly soda acrylamide copolymer was dissolved in methanol, mixed with the 7-summer solution of Example 1, mixed with the 7-summer solution of Example 1, and irradiated with near ultraviolet rays in the same manner as in Example 1. Intrinsic viscosity = 21.3 [dl/
g], water insoluble (%) = 0.13%. Compared to Example 1, the intrinsic viscosity was lower, and more water-insoluble polymers were present, resulting in inferior quality as a water-soluble polymer.

Example 2 In Practical Example 1, benzoin propyl ether was replaced with benzyl as an inclusion compound, and other conditions were kept the same to obtain a powder of a sodium acrylate acrylamide copolymer.

The powder had a high intrinsic viscosity of 29.8 [dl/g] and a low water-insoluble content (%) of 0.06%, both of which were superior to conventional powders.

Comparative Example 2 In Example 1, benzoin isopropyl ether was replaced with benzodyl, and the powder was dissolved in methanol without inclusion, keeping the other conditions the same, to obtain a powder of a sodium acrylate acrylamide copolymer.

The intrinsic viscosity of the powder was 20.7 [dt/g], and the water-insoluble content (%) was 0.17 (%).

Example 3 Commercially available β-cyclodextrin [manufactured by Hanui Chemicals] 12
．． 0g to isopropyl alcohol/water = 50wt, 5
After uniformly dissolving in 1.000 g of a mixed solvent of 7 wt%, 2.7 g of benzyl methyl ketal is mixed and stirred to uniformly dissolve.

After stirring for about 1 hour, the mixed solvent was completely evaporated under vacuum while externally heating with hot water at 70°C. The evaporated solid product obtained was white and had a molar ratio of β-cyclodextrin/benzyl methyl ketal. is about 1m.

1/1mo1. Weight ratio: 4.5wt, %/1wt・
It is estimated that % of the inclusions are present. Assuming that about 18% benzyl methyl ketal is contained in the finely powdered benzyl methyl ketal conjugate obtained by finely grinding this in a mortar, the benzyl methyl ketal conjugate is 0. Collect 067g. On the other hand, 285.0
An aqueous solution with a monomer concentration of 70.0%, the main component of which is methyl chloride quaternary salt of dimethylaminoethyl methacrylate of 80 mol % and acrylamide 20 mol %, was prepared by A, and the pH was 5.0. yJ, degassed with nitrogen gas, and removed oxygen to remove benzyl methyl ketal conjugate.
．． After dissolving 067 g in 30 g of water in advance and degassing with nitrogen gas, the solution was mixed into the monomer solution and stirred well.

At this time, the concentration of benzyl methyl ketal in 0.067 g of clathrate was about 60 ppm relative to the monomer solution.

This polymerization solution was placed in a polymerization container equipped with a jacket with a glass lid that was previously filled with nitrogen gas and had a structure in which 10'0 of cooling water was passed through the polymerization container, and a commercially available Toshiba chemical lamp FL20SBL type was used from the top.

Near ultraviolet light having a wavelength of 360 nm is irradiated, and after 50 minutes, the polymerization solution becomes a hard rubber-like elastic body. Take this out,
Grind into pieces of 2.0 mm to 3.0 mm with a commercially available meat grinder, dry with hot air at 70°C for 120 minutes, and prepare a quaternary powder of acrylamide-dimethylaminoethyl methacrylate with a moisture content of 9.2%. A polymer was obtained.

The intrinsic viscosity of this powder [lN-NaCl, 30°C J is 41
When the temperature was set to 1, it was a high value of [η] = 13.5 [dl/g].

The insoluble content (%) was as low as 0.01%, which was extremely excellent. In the conventional case, under such conditions, [η] = 7.0 to 8.
0[dl/g1. Insoluble content (%) = 0.04% is normal.

Example 4 In Example 3, isopropyl alcohol/water = 50
wt, 57wt, without using a mixed solvent of %,
By mixing and stirring 12.0 g of β-cyclodextrin and 2.7 g of benzyl methyl ketal in 30 g of water, dissolving them uniformly, and stirring for about 2.5 hours, β- 0.204 g of an aqueous solution of benzyl methyl ketal conjugate with cyclodextrin is collected. This contains 0.01 benzyl methyl ketal.
Contains 0,067 g of inclusions containing 23 g. In the same manner as in Example 3, 0.204 g of an aqueous solution of this conjugate was added to a 70-mer solution containing monomers with a ratio of 80 mol% of methyl chloride quaternary salt of dimethylaminoethyl methacrylate and 20 mol% of acrylamide as main components. In addition to 285 g of an aqueous solution having a pH of 5.0 at 0%, the same photopolymerization was carried out to obtain a powdery copolymer of acrylamide-dimethylaminoethyl methacrylate quaternary salt. At this time, the benzyl methyl ketal contained in the benzyl methyl ketal conjugate has a concentration of 6 oppm relative to the monomer liquid.

When this intrinsic viscosity was determined by l1111, [η]=13
, 3 [d l/g] and a low insoluble content of 0.01%, which was extremely excellent and not much different from Example 3.

Comparative Example 3 After preparing the aqueous solution of Example 3 without using β-cyclodextrin and dissolving 0.012 g of benzyl methyl ketal in 2.0 g of methanol without using it as an conjugate. The copolymer of powdered acrylamide-dimethyl 7-minoethyl methacrylate quaternary salt obtained by the same photopolymerization had [η] = 7.3 [dl/g
1. The insoluble content was 0.04%, which was inferior to both Example 4 and Example 3.

Claims (3)

[Claims] (1) A method for producing a water-soluble vinyl polymer by a photopolymerization method, which is characterized by using a polymerization initiator encapsulated with cyclodextrin. (2) The production method according to claim 1, wherein the polymerization initiator is a carbonyl compound. (3) The manufacturing method according to claim 1 or 2, wherein the wavelength of the irradiated light is centered around 360 nm.