JPH0676458B2 - Method for producing poly-N-vinylformamide - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing poly N-vinylformamide. Specifically, it relates to a method of polymerizing N-vinylformamide using an organic peracid compound as a polymerization initiator.

The poly (N-vinylformamide) obtained by the production method of the present invention is widely used in application fields of water-soluble and hydrophilic polymers. In particular, polyvinylamine obtained by hydrolyzing poly-N-vinylformamide exhibits an excellent effect in the field of use as an additive for papermaking and a coagulant for treating wastewater.

[Prior art and its problems]

N-vinylformamide is polymerized by a radical mechanism,
It is known to produce a polymer having a high molecular weight, and in order to obtain the polymer, any of the polymerization initiators used for the polymerization of a usual vinyl single polymer can be used. But,
Since N-vinylformamide is susceptible to decomposition by an acid and an oxidizing agent, it is disclosed in, for example, JP-A-59-33312 and JP-A-58-238.
As described in 09, an azo compound is suitable as a polymerization initiator. However, azo compounds have the property of being thermally decomposed in the first order, and their types are also extremely limited. For this reason, in a large-scale polymerization facility, when it is necessary to prevent heat accumulation during the polymerization reaction, the polymerization initiation temperature is kept low in the copolymerization reaction with a volatile comonomer,
There is a limit to the control of the polymerization temperature when it is necessary to prevent volatilization of the comonomer due to the heat of polymerization. On the other hand, for example, when N-vinylformamide is started at a low temperature using a polymerization initiator such as a persulfate salt used in the production of polyacrylamide and a redox polymerization initiator that uses a reducing substance to attempt polymerization, The decomposition reaction of N-vinylformamide was dominant, and the polymer could not be produced by freely controlling the polymerization temperature.

[Means for solving problems]

As a result of intensive studies by the present inventors, by using a specific organic peracid compound, while avoiding the decomposition of N-vinylformamide during the polymerization reaction, if necessary, a redox system mechanism in which a reducing substance is used in combination is used to control the polymerization temperature. The inventors have found that a high-molecular weight polymer can be produced in a high yield by freely controlling the above, and reached the present invention.

That is, the present invention relates to the use of an organic peracid compound having a half-life of 10 hours or less at a temperature of 110 ° C. or less as a radical polymerization initiator in a method of radically polymerizing N-vinylformamide to produce poly-N-vinylformamide. It lies in a method for producing a characteristic poly (N-vinylformamide).

[Structure of Invention]

As the polymerization initiator used in the present invention, an organic peracid compound having a low temperature activity, which has a half-life of 10 hours at a temperature of 110 ° C. or lower, preferably 90 ° C. or lower, more preferably 70 ° C. or lower is used. As specific examples of the organic peracid compound, there are usually used ketone peroxide, hydroperoxide, diacyl peroxide, dialkyl peroxide, peroxyketal, alkyl perester and percarbonate. Of these, preferred are ketone peroxides, diacyl peroxides, peroxyketals, alkyl peresters and percarbonates, and more preferred are diacyl peroxides, alkyl peresters and percarbonates. Alkyl peresters are particularly preferred.

An example of the above organic peracid compound is shown below.

[Ketone peroxide]: Methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, cyclohexanone peroxide, methyl cyclohexanone peroxide and the like.

[Diacyl peroxide]: isobutyryl peroxide, 2,4-dichlorobenzoyl peroxide, o-methylbenzoyl peroxide, bis-3,5,5-trimethylhexanoyl peroxide and the like.

[Dialkyl peroxide]: Tris (t-butylperoxy) triazine and the like.

[Peroxyketal]: 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-t-butylperoxycyclohexane, 2,2-di (t-butylperoxy) Butane, 4,4-di-t-butylperoxyvaleric acid n
-Butyl ester and the like.

[Alkyl perester]: 2,4,4-trimethylpentyl peroxyphenoxy acetate, α-cumyl peroxy neodecanoate, t-butyl peroxy neodecanoate, t-butyl peroxypivalate, t-butyl Peroxy-2-ethylhexanoate, t-butylperoxyisobutyrate, di-t-butylperoxyhexaanhydroterephthalate, di-t-butylperoxyazelate, t-butylperoxy-3,5 5,5-Trimethylhexanoate, t-butyl peroxyacetate, t-butyl peroxybenzoate, t-butyl peroctoate and the like.

[Percarbonate]: di-3-methoxybutylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, diisopropylperoxydicarbonate, di-sec- Butyl peroxy dicarbonate, t-butyl peroxy isopropyl carbonate and the like.

The organic peracid compound is used in an amount of 0.005 to 5% by weight, preferably 0.05 to 1% by weight, based on N-vinylformamide. The polymerization temperature is appropriately selected in the range of 0 ° C. to 100 ° C. depending on the molecular weight of the desired poly N-vinylformamide. When the polymerization is carried out in the range of 0 to 70 ° C., it is possible to carry out the polymerization with a redox type polymerization initiator which is used in combination with a reducing compound, if necessary. The reducing compound is used in an amount of usually 0.1 to 10 equivalents, preferably 0.5 to 2 equivalents, relative to the organic peracid compound. As the reducing compound, both an organic peracid compound to be used and a compound which causes a redox reaction can be used.

Examples of the reducing compound include ferrous ammonium sulfate, ferrous sulfate, cuprous chloride, sodium sulfite, sodium hydrogen sulfite, sodium bisulfite, sodium thiosulfate, dimethylaniline, and triethanolamine. In particular, if a compound having a strong reducing property such as a ferrous salt is used, a high molecular weight polymer can be produced in a high yield even at a low temperature condition of 0 to 40 ° C.

The method for producing poly-N-vinylformamide of the present invention can be applied to any known polymerization method such as bulk polymerization, solution polymerization, dispersion polymerization and emulsion polymerization. In particular, the present invention can be applied to bulk polymerization and high-concentration solution polymerization in which it is conventionally difficult to control the polymerization temperature.

In particular, in order to produce high molecular weight poly-N-vinylformamide, it is preferable to polymerize N-vinylformamide in the form of an aqueous solution. In order to obtain a high molecular weight polymer, it is preferable to polymerize in a monomer concentration range of 10 to 60% by weight. However, in an aqueous solution, a part of N-vinylformamide may be decomposed by the acidic substance generated by the decomposition of the organic peracid compound. Therefore, in the polymerization reaction solution in advance
It is preferable to add a compound having a pH buffering effect in advance so that the pH becomes 4.5 or more when the polymerization rate reaches 90% or more. As the compound having a pH buffering action, any water-soluble weakly basic substance can be used. For example phosphoric acid,
Examples are salts of weak acids such as boric acid and carboxylic acid with strong bases such as sodium hydroxide and potassium hydroxide, ammonia and amines. The amount of the substance having a pH buffering action is appropriately selected within a range that does not affect the polymerization reaction.

In the present invention, the vinyl monomer to be radically polymerized may be copolymerized with N-vinylformamide and another vinyl monomer. In this case, N-vinylformamide is usually contained in an amount of 10 mol% or more, preferably 20 mol% or more, based on all vinyl monomers. The vinyl monomer used for copolymerization with N-vinylformamide is not particularly limited, but the effect of the present invention can be greatly utilized especially when copolymerizing with a volatile vinyl monomer. Examples of the volatile vinyl monomer include vinyl acetate, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, acrylonitrile, methacrylonitrile, vinyl methyl ether and the like. Further, non-volatile monomers such as acrylamide, methacrylamide, acrylic acid and salts thereof, N, N-dimethylacrylamide, and Nt-butylacrylamide can be copolymerized in the same manner.

〔Example〕

Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Test tube 100ml equipped with Examples 1 to 7 and Comparative Examples 1 to 3 three-way cock 1 / 30M-KH ₂ PO ₄ and 1 /
40 g of a buffer solution having a concentration of 30 M Na ₂ HPO ₄ and 10 g of N-vinylformamide were added. Under ice cooling, 6.5 × 10 ⁻⁵ mol of the polymerization initiator and a reducing substance equimolar to the polymerization initiator shown in Table 1 were added to the solution (excluding Example 7 and Comparative Example 3).

Connect one side of the three-way cock to the nitrogen gas supply system and the other side to the vacuum system.
Replaced twice. After keeping at the temperature shown in Table 1 for 24 hours under sealing, the reaction solution was discharged into 500 ml of acetone to precipitate a polymer, and the mixture was filtered. Then, this polymer was vacuum dried at 40 ° C. for 15 hours to obtain a solid dry polymer. The yield of the polymer and the reduced viscosity (η measured at 25 ° C. with an Ostwald viscometer were obtained by dissolving the polymer in 1N saline at a concentration of 0.1 g / dl.
The values of sp / c) are shown in Table 1.

EFFECTS OF THE INVENTION According to the present invention, N-vinylformamide can be polymerized by using a specific organic peracid compound and, if necessary, in combination with a reducing substance. Even in a polymerization system containing a volatile monomer, it is easy to control the polymerization temperature, which largely contributes to the productivity of poly N-vinylformamide.

Claims (6)

[Claims] 1. A method for producing poly-N-vinylformamide by radical polymerization of a vinyl monomer containing N-vinylformamide, wherein an organic solvent having a half-life of 10 hours as a radical polymerization initiator is 110 ° C. or lower. A method for producing poly-N-vinylformamide, which comprises using an acid compound. 2. The method for producing poly-N-vinylformamide according to claim 1, wherein the radical polymerization temperature is 0 to 100 ° C. 3. The poly-N according to claim 1, wherein the organic peracid compound is a diacyl peroxide, an alkyl perester or a percarbonate.
-Method for producing vinylformamide. 4. The method for producing poly (N-vinylformamide) according to claim 1, wherein the organic peracid compound is used in an amount of 0.005 to 5% by weight based on N-vinylformamide. 5. The pH of N-vinylformamide in an aqueous medium
Polymerization in the presence of a substance having a buffering action, and maintaining the pH at 4.5 or higher when the polymerization rate reaches 90% or higher, the production of poly-N-vinylformamide according to claim 1. Method. 6. Radical polymerization is performed on an organic peroxy acid compound in an amount of 0.
The method for producing poly-N-vinylformamide according to claim 1, wherein the polymerization is initiated at 0 to 70 ° C in the coexistence of a reducing substance in an amount of 2 to 5 times.