JPH0423805A - Production of benzyl polymethacrylate resin particle - Google Patents

Abstract

PURPOSE:To readily obtain the subject real round particles having a remarkably narrow particle size distribution without using a special dispersant by using a specified hydrophilic solvent as a dispersion solvent in dispersion polymerization of benzyl methacrylate monomer. CONSTITUTION:In polymerization of benzyl methacrylate (monomer) in a hydrophilic solvent containing a polymer dispersant dissolved therein, a hydrophilic mixture solvent composed of 60-100wt.% methyl alcohol and 40-0wt.% N,N'-dimethylformamide is used to obtain the objective particles. In addition, the above-mentioned polymerization is preferably carried out by using a polymerization initiator in an amount of 0.2-5wt.%, based on the monomer, at 45-110 deg.C under stirring of 100-500rpm of agitation. As the polymer dispersant, polyvinyl pyrrolidone or PVA is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing truly spherical polybenzyl methacrylate resin particles having an average particle diameter of 1 to 15 μm, and more specifically, to a method for producing truly spherical polybenzyl methacrylate resin particles that are easy to control the particle diameter, And especially the average particle size 2
The present invention provides a method for producing polybenzyl methacrylate resin particles having a narrow particle size distribution in the range of 8 μm.

[Conventional technology]

It has been difficult to produce polymer particles having a particle size of approximately 1 to 100 μm and having a uniform particle size, although there are many demands for column packing materials, various spacers, diagnostic agent carriers, and the like.

Conventionally, polymer particles with such particle sizes have been generally produced by suspension polymerization, seed emulsion polymerization, dispersion polymerization, etc. It is difficult to obtain narrow polymer particles; therefore, in order to obtain polymer particles with a desired particle size distribution, a classification step is required to make the particle sizes of the polymer particles obtained by the suspension polymerization uniform; The problem is that the process is complicated and time-consuming, but the yield is not good.Also, although this method is suitable for producing polymer particles with a relatively large particle size, it has an average particle size of several μm. Another problem is that it is difficult to produce microparticles of, for example, 8 μm or less.

On the other hand, the sheet emulsion polymerization method is suitable for obtaining polymer particles with a narrow particle size distribution, but even if this sheet emulsion polymerization is performed carefully, the average particle size of the resulting polymer particles is at most 2 μm or less. However, when trying to obtain particles with a larger particle size, there is a problem that the polymerization reaction rate is extremely slow and practical production is difficult.

In order to improve the problems in the above seed emulsion polymerization method,
An improved method of polymerizing the seed particles while absorbing the swelling aid and subsequently absorbing the monomer components is disclosed in, for example, JP-A-54-126288 and JP-A-61-2156.
This is proposed in Publication No. 04 and the like. According to this method, polymer particles with a large particle size and a narrow particle size distribution can be obtained relatively easily. In addition to the problem that the process becomes complicated, the obtained polymer particles contain a swelling aid, which may become an impurity when used for various purposes, so this is preferable.

In contrast, a dispersion polymerization method involves starting a polymerization reaction from a homogeneous solution system in which a dispersion stabilizer, a polymerizable monomer, and a polymerization initiator are dissolved in a solvent as a dispersion medium to produce polymer particles. Since it is possible to produce polymer particles with a relatively large particle size and a narrow particle size distribution, it has attracted attention in recent years, and many methods including improved methods have been proposed in various documents.

For example, JP-A No. 61-19602 discloses that a specific amount of a polymer dispersant that dissolves in a hydrophilic organic liquid and a polymer dispersant that is dissolved in the hydrophilic organic liquid but produced are A dispersion polymerization method has been disclosed in which polymerization is performed by adding a specific amount of one or more vinyl monomers that swell or hardly dissolve. The particle size of the resulting polymer particles is controlled by changing the solubility parameter of the hydrophilic tIt liquid.

However, although the dispersion polymerization method disclosed in the above publication is suitable for producing polystyrene resin particles,
When producing polybenzyl methacrylate resin particles from a methacrylic acid ester monomer, particularly a hensyl methacrylate monomer, there is a problem in that it is difficult to control the particle size or particle size distribution, and the resulting polymer particles are In order to continue polymerization while maintaining a stable dispersion state in the liquid, there is a problem that a special dispersant is required, and this method is not necessarily preferred.

[Problem that the invention seeks to solve]

The present invention has been developed through extensive studies aimed at solving the problems of the conventional methods described above, namely, that it is difficult to produce polybenzyl methacrylate resin particles with a relatively large particle size and a narrow particle size distribution. As a result, by using a specific hydrophilic solvent as a dispersion solvent in dispersion polymerization, an average particle size of 1 to 15% can be obtained without using a special dispersant.
It has been discovered that truly spherical polymethacrylic acid Henssil resin particles with a controlled particle diameter of 1 μm can be easily produced, and in particular, resin particles with an extremely narrow particle size distribution in the average particle diameter range of 2 to 8 μm can be produced. Thus, the present invention was completed.

[Means to solve the problem]

The method for producing polymethacrylic acid Hensyl resin particles of the present invention (hereinafter referred to as the present invention method) comprises dispersing and polymerizing polymethacrylic acid Hensyl monomers in a hydrophilic solvent containing a polymeric dispersion stabilizer dissolved therein. In the method for producing Henshil resin particles (hereinafter referred to as PMB resin particles), the hydrophilic solvent includes (a) 60 to 100% by weight of methyl alcohol, and (b) 40 to 0% by weight of N,N-dimethylformamide. It is characterized by using a solvent having the following composition.

The method of the present invention having the above configuration uses methyl alcohol or a mixed solvent of methyl alcohol and N,N-dimethylformamide as a dispersion solvent during dispersion polymerization, and dispersion polymerizes henzyl methacrylate monomer in the solvent. The most important feature is that the particle size can be controlled without using any special dispersion stabilizer by simply changing the amount of N,N-dimethylformamide mixed with methyl alcohol within the above range of 0 to 40% by weight. It is possible to easily produce true spherical PMB resin particles with an average particle diameter of 1 to 15 μm, and to produce PMB resin particles with an extremely narrow particle size distribution of 2 to 8 μm in average particle diameter.

Therefore, in the method of the present invention, the hydrophilic solvent used as the dispersion solvent has a composition range of (a) 60 to 100% by weight of methyl alcohol, and (b) 40 to 0% by weight of N,N-dimethylformamide. It is particularly important that the hydrophilic solvent contains less than 60% by weight of methyl alcohol, N, N
- more than 40% by weight of dimethylformamide;
Since the dispersion solvent easily dissolves polybenzyl methacrylate, the PMB resin particles produced by polymerization also swell in the polymerization system, causing welding of the particles or cracking of the particles, and the particles are removed from the polymerization system. The disadvantage is that it is often difficult to do so.

In addition, in the method of the present invention, true spherical PMB resin particles can be obtained even when the hydrophilic solvent is only methyl alcohol, but methyl alcohol has no affinity for polybenzyl methacrylate produced by polymerization. ,
Hensyl methacrylate monomer tends to turn into particles at the same time as it polymerizes, producing microparticles of 1 μm or less. In some cases, the microparticles cannot be stabilized by themselves, and the particles coalesce and become larger. There is a risk that the particles will be of irregular size and shape and have a wide particle size distribution.
The hydrophilic solvent used in the method of the present invention is preferably a mixed solvent having a composition of 65 to 80% by weight of methyl alcohol and 35 to 201% by weight of N,N-dimethylformamide.

The amount of the benzyl methacrylate monomer used is not particularly limited, but it is generally preferable to use it in the range of 2 to 50% by weight of the entire polymerization system including the dispersion solvent, and the amount of the monomer used is within this range. If the amount is outside the range, the influence of solution polymerization that occurs concurrently in the dispersion polymerization system will be significant. It is difficult to precipitate and take out as particles. Furthermore, when the amount of benzyl methacrylate monomer used exceeds 50% by weight, this monomer also acts as a good solvent for the polymer, so that relatively 1! ! A state with a large amount of solvent is formed, and at the beginning of polymerization, the produced polymer may dissolve in the parent solvent and not form particles, but as the polymerization progresses, the solubility of the polymer in the polymerization system decreases rapidly. , a large amount of polymer rapidly precipitates, and the precipitated polymer does not form a true spherical shape and tends to become amorphous polymer particles, and furthermore, the particles tend to aggregate and destabilize the polymerization system.

The polymeric dispersion stabilizer that can be used in the method of the present invention exists on the particle surface and prevents agglomeration of particles and stabilizes the dispersion state, so it has affinity for both the polymerization solvent and the polymer. It is necessary that the polymer is amphiphilic, and it is desirable that it is bulky in the polymerization solvent. You can, but
It is preferable to use a water-soluble polymer dispersion stabilizer because it can be easily removed from the surface of the resulting polymer particles.
Furthermore, polyvinylpyrrolidone, polyvinyl alcohol, and the like are preferred from the viewpoint of dispersion stability, ease of handling, economy, availability, and the like.

The amount of the polymeric dispersion stabilizer used is generally preferably in the range of 0.1 to 10% by weight, particularly in the range of 0.3 to 3% by weight, based on the total amount of monomer and dispersion solvent. If the amount of the dispersion stabilizer used is less than 0.1% by weight, the dispersion stability performance will be insufficient, and the particles will aggregate during polymerization, making it impossible to obtain individual polymer particles. On the other hand, if the amount exceeds 10% by weight, the viscosity of the polymerization system becomes too high and the polymerization system cannot be stirred sufficiently, causing agglomeration easily, and the particles obtained by polymerization are Cleaning becomes too time consuming.

The dispersion polymerization method used in the method of the present invention itself is not as special as it is, and conventionally known methods can be used as they are; for example,
A desired amount of a hydrophilic solvent, a dispersion stabilizer, a benzyl methacrylate monomer, and a polymerization initiator are added to a suitable reaction vessel, mixed uniformly, and the inside of the reaction vessel is purged with nitrogen, followed by heating and polymerization with stirring. True spherical PMB resin particles with an average particle diameter of 1 to 15 μm are produced. In addition, the generated PM
The particle size and particle size distribution of the B resin particles are influenced by the composition of the dispersion solvent used, the type of dispersion stabilizer, and their amount, as well as the stirring speed during the polymerization reaction, polymerization temperature, and the type and amount of the polymerization initiator. Generally, it is preferable to carry out the polymerization under conditions such as a stirring speed of 100 to 500 rpm, a polymerization temperature of 45 to 110° C., and an amount of polymerization initiator of 0.2 to 5% by weight based on the monomer.

The PMB resin particles obtained as described above are then removed from the polymerization system by methods such as filtration and centrifugation, and impurities such as dispersion stabilizers adhering to the resin particles are removed using an appropriate solvent such as water or methanol. After washing at , drying at a temperature below the glass transition point of the obtained resin (for example, drying under reduced pressure, etc.),
If necessary, crush the P with a homogenizer etc.
MB resin particles are obtained.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example-1 In a glass bottle with a capacity of 300 cc, 90 g of methyl alcohol and 1 g of polyvinylpicolidone were added as a dispersion solvent.
10 g of Hensyl methacrylate and 0.2 g of azobisisobutyronitrile as a polymerization initiator were charged, and after purging the inside of the glass bottle with nitrogen, the glass bottle was sealed.

After shaking the glass bottle at room temperature to uniformly dissolve the contents, the glass bottle was transferred to a shaking polymerization tank and incubated at 50°C for 8 hours.
Polymerization was carried out by adding shaking at 160 times/min.

The resin particles produced by polymerization are separated from the dispersion solvent by centrifugation, redispersed in methanol at room temperature to wash the dispersion stabilizer and residual monomer, and then centrifuged again to remove the supernatant. When the wet powder of the particles was dried under reduced pressure at a temperature below the glass transition point of the resin, and the dried particles were crushed using a homogenizer, perfectly spherical PMB resin particles were obtained.

The particle size of the PMB resin particles obtained as above is
When measured with Coulter Counter FA-1 manufactured by Coulter Electronics, the average particle diameter was 1.64.
μm, and the coefficient of variation of the particle size distribution, which indicates the spread of the particle size distribution, was 50.3%.

Incidentally, the coefficient of variation of the particle size distribution was calculated from the measured value of the average particle diameter using the following formula.

Examples 2 to 8 PMB resin particles were produced in exactly the same manner as in Example 1, except that the composition of the dispersion solvent in Example 1 was changed to the composition shown in Table 1 below.

All of the obtained PMB resin particles were perfectly spherical, and the average particle size and particle size distribution were measured in the same manner as in the example above, and the results were as shown in Table 1.

(The following is a blank space) Table [Effects of the Invention] The method of the present invention is a simple method that only uses the above-mentioned specific hydrophilic solvent as a dispersion solvent when producing polymethacrylic acid Henssil resin particles by dispersion polymerization. Regardless of the particle size distribution of the resulting resin particles, especially 2 to 8μ
For particles with a size of m, the particle size distribution is extremely narrow, with a coefficient of variation of about 10% or less, and the average particle size can be controlled extremely easily. Since there is no need to use a chemical agent, particles free of impurities can be obtained, making it an extremely practical method.

Patent applicant: Fujikura Kasei Co., Ltd.

Claims (3)

[Claims] (1) In a method for producing polybenzyl methacrylate resin particles by dispersion polymerizing a benzyl methacrylate monomer in a hydrophilic solvent containing a dissolved polymer dispersion stabilizer, as the hydrophilic solvent: (a) methyl alcohol; 60 to 100% by weight, and (b) 40 to 0% by weight of N,N-dimethylformamide. A method for producing benzyl polymethacrylate resin particles. (2) The hydrophilic solvent is methyl alcohol 65-80%
Weight % and N,N-dimethylformamide 35-20
The method for producing benzyl polymethacrylate resin particles according to claim 1, which is a mixed solvent of % by weight. (3) The method for producing polybenzyl methacrylate resin particles according to claim 1, wherein the polymer dispersion stabilizer is polyvinylpyrrolidone or polyvinyl alcohol.