JPS5814426B2 - Method for stabilizing unsaturated tertiary amine or its quaternary ammonium salt - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for stabilizing unsaturated tertiary amino or its quaternary ammonium salt.
The present invention relates to a method for stabilizing ammonium salts.

Homopolymers of dimethylaminoethyl methacrylate and its quaternary ammonium salts or copolymers of these unsaturated compounds with acrylamide, vinylpyridine salts, methyl acrylate, methyl methacrylate, styrene, acrylonitrile, vinyl acetate, etc. are water-soluble polymers. It is used for various purposes as a water treatment agent or flocculant.

Specifically, it is used as a clarifying agent for factory wastewater, urban sewage, livestock wastewater, papermaking wastewater, etc., as a dehydrating agent for various sludges, and as a filler retention improver and paper strength enhancer in the paper industry.

Furthermore, dimethylaminoethyl methacrylate and its quaternary ammonium salt are used to impart dyeability to acrylic synthetic fibers, as antistatic agents for various polymer compounds, lubricating oil additives, thermosetting resin paints, etc. It is used industrially as a useful compound with a wide range of uses.

By the way, although dimethylaminoethyl methacrylate and its quaternary ammonium salt are useful, they have a property of being extremely easy to polymerize, which is a serious drawback from an industrial standpoint.

For example, dimethylaminoethyl methacrylate is generally produced by subjecting methacrylic acid or its ester to an esterification reaction or transesterification reaction with aminoethanols.

After completion of the reaction, the crude product is purified by distillation under reduced pressure to separate it from unreacted raw materials and side reaction products.

During transesterification or distillation, the reaction mixture is usually heated to a temperature of 60°C or higher, so the compound represented by formula (1) may polymerize in the reaction vessel and distillation vessel, resulting in a significant decrease in yield. , causing process problems such as making the equipment unusable.

The quaternary ammonium salt of dimethylaminoethyl methacrylate is prepared by dimethylaminoethyl methacrylate with hydrochloric acid,
It is produced by neutralizing it by adding sulfuric acid or the like, or by reacting dimethylaminoethyl methacrylate with a quaternization reaction reagent in an organic solvent or an aqueous medium to quaternize it.

Among these production methods, in the case of the former method, the neutralization reaction is carried out while preventing the reaction mixture from reaching a temperature of 60° C. or higher, but the desired product may already undergo polymerization during neutralization.

In the case of the latter, quaternization in an organic solvent is carried out in a polar solvent such as acetonitrile or dimethylformamide, and the quaternized product is relatively stable during synthesis, but during the recovery process of the organic solvent after the reaction or Spontaneous polymerization may occur during the product drying process.

On the other hand, in quaternization in an aqueous medium, the reaction mixture can be directly used to produce a quaternized polymer after the reaction, and the polymer production process is simpler than in the case of quaternization in an organic solvent. This method is currently attracting attention because it is simple and can reduce product prices.

This quaternization in an aqueous medium is carried out by adding a quaternizing agent to a 50-95% aqueous solution of dimethylaminoethyl methacrylate under pressure or normal pressure, and reacting at a temperature of 10-60°C. During this quaternization reaction, the quaternized product often undergoes spontaneous polymerization.

In this way, when dimethylaminoethyl methacrylate and its quaternary ammonium salt undergo spontaneous polymerization during the synthesis process, the synthesis yield decreases, and the polymer obtained by spontaneous polymerization is usually an insoluble polymer or is not suitable for practical use. It cannot be used because it has a neutral molecular weight.

In addition, when synthesizing a quaternary ammonium salt in an aqueous medium, if the compound partially polymerizes, it becomes impossible to add a polymerization initiator when directly polymerizing the reaction solution, making it difficult to smoothly produce a polymer. becomes.

Thus, dimethylaminoethyl methacrylate and its quaternary ammonium salt are easily polymerized during synthesis.

In particular, an aqueous solution of a quaternary ammonium salt with a concentration of 60% or more tends to polymerize. For example, an 80% aqueous solution of methacroyloxyethyltrimethylammonium chloride is a hydroquinone monomethyl ether, which is well known as a polymerization inhibitor for vinyl monomers. Even if 1000 ppm of is added, it will polymerize after one day.

Traditionally, to prevent polymerization of dimethylaminoethyl methacrylate and its quaternary ammonium salts, these compounds have been treated with stabilizers such as hydroquinone, hydroquinone monomethyl ether, and t-butylcatechol, just as with other unsaturated monomers. (polymerization inhibitor) is added.

However, this type of polymerization inhibitor does not have a good stabilizing effect on dimethylaminoethyl methacrylate and its quaternary ammonium salt, and for example, when the purpose is storage, it is added at about 500 to 5000 ppm to these compounds. However, this polymerization inhibitor acts as a chain transfer agent when dimethylaminoethyl methacrylate or its quaternary ammonium salt is polymerized, and therefore has the disadvantage that a high molecular weight polymer useful as a flocculant cannot be obtained. It has been revealed that adding a larger amount of this type of stabilizer does not necessarily improve storage stability.

More recently, a method has been proposed in which a polymerization inhibitor is added to dimethylaminoethyl methacrylate and its quaternary ammonium salt, and then oxygen is mixed in to stabilize the mixture.

(Refer to Japanese Unexamined Patent Publication No. 127016/1983) However, with this method, one must always be careful about the amount of oxygen, and dimethylaminoethyl methacrylate and its quaternary ammonium salt must be stored or transported in drums. This is inconvenient in some cases.

Furthermore, quaternary ammonium salts are often treated as an aqueous slurry with a concentration of 80% or higher in order to obtain powder from the polymer, but in this case, a considerable amount of crystals are mixed in, resulting in a high viscosity of the slurry and oxygen There are problems such as not being able to inject aeration, or even if aeration is possible at first, if aeration is continued for a long period of time, crystals will adhere to the aeration pipe, clogging the pipe and making aeration impossible.

For this reason, there has been a desire for a stabilizer that has an excellent polymerization inhibiting effect on dimethylaminoethyl methacrylate and its quaternary ammonium salt, and that allows easy control of polymerization when these compounds are polymerized.

The present invention was made in response to such a need, and as a result of intensive studies on stabilizers for dimethylaminoethyl methacrylate and its quaternary ammonium salts, the present inventors found that Lou N
The inventors have discovered that very good results can be obtained by adding a -heterocyclic compound as a stabilizer to dimethylaminoethyl methacrylate or its quaternary ammonium salt, and have arrived at the present invention.

Types of αα・ωω-tetra-lower alkylpiperidine compounds used in the present invention include the compounds shown in (1) to (10) below, among which triacetonamino (
8-4-acetoxy 2,2,6,6-tetramethylpiperidine (2), 4-dimethylamino-2,2,6,6-
Tetramethylpiperidine (3), 4,4-dimethoxy2,2,6,6-tetramethylpiperidine (4), 4-
Suitable examples include αα·ωω-tetra-lower alkylpiperidine compounds such as benzoyloxy-2,2,6,6-tetramethylpiperidine (5).

(Here, R1, R2, R3 and R4 represent CH3 or C2H, and R5 and R6 represent H, CH3
or C2H.

) These stabilizers (hereinafter referred to as the stabilizers of the present invention)
The amount used depends on the type of dimethylaminoethyl methacrylate and its quaternary ammonium salt to be stabilized, the type of stabilizer used, and the use of stabilized dimethylaminoethyl methacrylate and its quaternary ammonium salt. Various changes are made depending on the purpose.

Normally, when synthesizing or purifying dimethylaminoethyl methacrylate, heating is often performed, so in such cases, the stabilizer of the present invention is added to the compound at a concentration of 1 to 100%.
Add 00ppm.

On the other hand, when synthesizing a quaternary ammonium salt, there is no need to raise the temperature to high temperatures, and the synthesized product is usually subjected to polymerization, etc. without being purified, so in this case, it is necessary to take care not to interfere with the polymerization. 1 to 1000 ppm of the stabilizer of the present invention is added to the compound.

When dimethylaminoethyl methacrylate or its quaternary ammonium salt is stored, the stabilizer of the present invention is usually added in an amount of 0.1 to 2,000 ppm.

As is clear from the examples below, the αα・ωω-tetra-lower alkylpyheridine compound used as a stabilizer in the present invention can be added to dimethylaminoethyl methacrylate or its quaternary ammonium salt in an appropriate amount to stabilize these unsaturated compounds. These unsaturated compounds themselves or their aqueous solutions can be stabilized for a long period of time without any adverse effect on the polymerizability of the compound or the physical properties of the polymerized product.

In carrying out the present invention, a conventionally known stabilizer may be used in combination with the stabilizer of the present invention, and the effects of the present invention will not be impaired thereby.

Next, the present invention will be explained with reference to examples.

Example 1 342.4 g of dimethylaminoethyl methacrylate and 67.6 g of pure water were placed in a glass autoclave with an effective volume of 1 liter.
, and 4,4-dimethoxy-2,2, as a polymerization inhibitor.
Charge 50 mg of 6,6-tetramethylpiperidine, and reduce the pressure inside with an aspirator.

Next, after raising the internal temperature to 30°C, methyl chloride 12
0 g was injected over 2 hours.

Once the reaction begins, the internal temperature will rise, but do not exceed 40°C.

After reacting for 3 hours, the system became uniform and transparent, but the reaction was continued for 30 minutes to complete the reaction.

Final pressure is 0. It was 3 kg/cm'-G.

Since this amount of methyl chloride added is 10% excess, the excess methyl chloride is released at a temperature of 40° C. after the reaction is completed.

Even if the pressure is lowered to normal pressure, methyl chloride is still dissolved in the system, so methyl chloride is removed by reducing the pressure with an aspirator.

Crystals precipitate from the aqueous medium of methacryloyl quinethyltrimethylammonium chloride obtained in this way when it reaches room temperature (25°C), but there is no sign of polymerization even if this product is left in the dark for one month. I was not able to admit.

Next, 300 ppm of azobisparellonitrile and 1 liter of Rongalit were added to the aqueous medium containing the monomer as a polymerization initiator.
00 ppm was added and polymerized.

As a result, polymerization was initiated within an induction period of 5 minutes, and the resulting polymer was easily powdered when struck with a hammer.

In addition, the viscosity of the 1% aqueous solution was measured at 25°C and A
When measured using 3 rotors at 6 rpm, 6
300 cps, indicating that it has very excellent properties as a flocculant.

Comparative Example 1 500mg of monomethylhydroquinone as a polymerization inhibitor
An attempt was made to synthesize methacryloyloxyethyltrimethylammonium chloride using the same method as in Example 1, but polymerization started slightly just before the end of the reaction, and the resulting aqueous medium of the desired product was viscous. It was clear that polymerization had occurred.

When this product was left in a dark place for one month, it completely polymerized.

Example 2 A quaternary ammonium salt powder obtained by reacting dimethylaminoethyl methacrylate and methyl chloride in acetonitrile was made into an 80% aqueous solution, and a stabilizer as listed in Table 1 was added to this, This sample was placed in a polyethylene sample bottle, capped, and left in a constant temperature bath at 60°C, and the stability of the sample was examined based on the presence or absence of polymer formation.

The results obtained are shown in Table 1.

Example 3 80 g of dimethylaminoethyl methacrylate was placed in a 100 cc polyethylene sample bottle, the stabilizer listed in Table 2 was added thereto, the sample was stored in a relatively bright place away from direct sunlight, and the polymer The stability of the sample was examined based on the presence or absence of formation.

The results obtained are shown in Table 2.

Claims (1)

[Scope of Claims] 1. A method for stabilizing unsaturated tertiary amino or its quaternary ammonium salt, which comprises adding the following compound to dimethylaminoethyl methacrylate or its quaternary ammonium salt. Triacetone amino, 4-acetoxy 2,26,6-
Tetramethylpiperidine, 4-dimethylamino-2.2
- At least one selected from the group consisting of 6,6-tetramethylpiperidine, 4,4-dimethoxy2, 2,6,6-tetramethylpiperidine and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine One type of α
α・ωω-Tetra-lower alkylpiperidine compound.