JPS5871902A - Preparation of vinyl polymer beads - Google Patents

Abstract

PURPOSE:To obtain titled beads with relatively uniform size by the suspension polymerization of a vinyl monomer in the presence of a sparingly soluble phosphate and an anionic surfactant and by adding, at specific points, an ethylenediamine tetraacetic acid chelate and the phosphate mentioned above respectively. CONSTITUTION:A suspension polymerization of a vinyl monomer (e.g., styrene) is carried out in the presence of (1) 0.01-1wt%, based on the amount of the total reaction system, of a sparingly soluble phosphate (e.g., calcium phosphate) and (2) 0.0002-0.02wt% of an anionic surfactant (e.g., sodium dodecylbenzenesulfonate) in such a way that either before the initiation of the polymerization or prior to reaching a conversion of 30%, at least 0.001wt%, based on the monomer, of an ethylenediamine tetraacetic acid chelate is added, and at a conversion between 30 and 70%, the phosphate mentioned above is incorporated in the system.

Description

[Detailed description of the invention] The present invention is based on suspension polymerization of vinyl monomers.

This invention relates to a method for obtaining vinyl polymer particles with a narrow particle size distribution.

Generally, polymer particles produced by suspension polymerization are dispersed in water by stirring and the action of a suspending agent (dispersing agent). It is produced by polymerizing at least one kind of vinyl monomer in the form of particles. The suspending agent has the function of preventing vinyl monomers or mixtures of monomers and polymers, that is, oil particles, from coalescing into lumps.

Conventionally, the use of vinyl monomers mainly based on styrene-1
It is well known that the suspending agent used in the above method uses a sparingly soluble phosphate as the main suspending agent and an anionic surfactant as the suspending agent.

specifically? i l) Tricalcium phosphate and sodium dodenrubensene sulfonate are the most common suspending agents.

The particle size of the polymer particles produced by suspension polymerization using this suspending agent was in the range of about 0.1 to 31 ran, and the particle size distribution was wide. Conventionally, it has been possible to arbitrarily control the particle diameter of the bipolymer particles by mechanical factors such as the degree of suspending agent and the stirring effect. However, it has been extremely difficult to narrow the particle size distribution of single polymer particles.

Polymer particles mainly composed of styrene obtained by hanging f@polymerization are treated with a blowing agent (e.g., propane, butane, peatane, etc.)
(Ill-impregnation, the desired expandable polystyrene resin is obtained. The use of expandable polystyrene resin is divided into three primary fields depending on the particle size. Namely, (1) particle size from about 300μ to Expandable polystyrene particles with a diameter of 700μ are used for cups such as instant foods, (2) particles with a particle size of about 700μ to 1800μ are used for various types of packaging and fish boxes, and (3) particles with a diameter of about 1500μ to 3
000μ is used for boards for building materials, etc. Ko'
7. Due to the different uses, the required properties of expandable polystyrene also differ.
However, if the particle size distribution of the polymer particles obtained by suspension polymerization is wide, it is difficult to achieve this purpose.

The present invention solves all of these problems.

That is, 1. the present invention provides a method for aqueous suspension polymerization of vinyl monomers in the presence of a sparingly soluble phosphate and an anionic surfactant, before the start of 2 polymerization or at a polymerization conversion rate of 30 ml,
%-1: 0.0 to the above vinyl monomer
01 mft % or more of ethylenediaminetetraacetic acid chelate is added, and after the addition of the ethylenediaminetetraacetic acid chelate, hardly soluble phosphorus is added to the polymerization system between the bundling conversion rate of the vinyl monomer of 20% by weight and 60% by weight. The present invention relates to a method for producing vinyl polymer particles characterized by adding an acid salt one or more times to advance polymerization.

Examples of the vinyl monomer in the present invention include styrene, α
-Methylstyrene, vinyltoluene.

Examples include styrene derivatives such as parachlorostyrene, acrylonitrile, acrylic esters, methacrylic esters, vinylhyridine, vinylcarbazole, butadiene, etc., and it is preferable to use 50 or more styrene derivatives in the styrene slurry.

Tricalcium phosphate is a poorly soluble phosphate.

Magnesium phosphate, etc., and those having a size of 0.2 to 0.05 μm, which is called a submicron unit, are useful. The total amount of sparingly soluble phosphate used is 0.01 or more based on the total amount of substances present in the polymerization system, although there is no particular upper limit.

If it exceeds 1 weight limit, it will be wasted as it will exceed the necessary effort. Preferably O, (15 to 0.5 cars 1 - used. 0.0
If the amount is less than 1% by weight, the particle size distribution of the produced polymer particles cannot be narrowed. What is the amount of poorly soluble phosphate initially present in the reaction system?

Although there is no particular restriction within the above range, it is preferably used from 1/4 to 3/4 of the total amount of poorly soluble phosphates.

Ionic surfactants include, for example, alkylbensene sulfonates such as sodium dodecylbensene sulfonate;
Alkyl sulfonate with S0sNa added directly to the alkyl group, β- with S UsNa added to naphthalene
Tetrahydronaphthalene sulfonic acid W, andosulfonic acids such as sodium N-isopropylene chlorohexyl acid sulfonate, higher fatty acids tM such as sodium oleate, dialkyl sulfosuccinic acids such as sulfosuccinic acid ff)-2-ethylhexyl=5-sodium, etc. Acid salts are used. The amount of these additions is not determined by the target particle size, mechanical conditions, suspending agent concentration, etc., but as a rough guide, it is 0.0002 to 0.02 to the total volume.
Weight support and flexibility range from 0.001 to 0.01 weight/density.

As the polymerization initiator, polymerization initiators that are generally used for radical polymerization of vinyl monomers can be used, such as organic peroxides such as benzoyl peroxide and butyl perbenzoate, and azo compounds such as azobisisobutylnitrile. . Furthermore, various additives used in radical polymerization, such as chain transfer agents such as other mercaptans, can also be added as necessary.

Ethylenediaminetetraacetic acid chelate is neutral in aqueous systems and contains zinc ethylenediaminetetraacetate, calcium ethylenediaminetetraacetate, iron ethylenediaminetetraacetate, copper ethylenediaminetetraacetate, lead ethylenediaminetetraacetate, cobalt ethylenediaminetetraacetate, bismuth ethylenediaminetetraacetate, and ethylenediaminetetraacetate. Examples include nickel diaminetetraacetate, barium ethylenediaminetetraacetate, magnesium ethylenediaminetetraacetate, manganese ethylenediaminetetraacetate, and the like. These ethylene diamine tetraacid chelates may be used alone or in combination.

These usage amounts (~0.00 for the single j unit)
01 City amount section or above. If the weight ratio is less than 0.0001, the particle size distribution of the produced polymer particles cannot be narrowed. I cut it. Even if it exceeds 0.055 parts by weight, no increase in the effect can be expected, so 0.05 parts by weight or less is sufficient.

It is preferable to add the ethylenediaminetetraacetic acid chelate before the start of suspension polymerization and at the beginning of shaking.

In particular, to narrow the width of the particle size distribution, the polymerization conversion rate is 30% by weight.
This can be achieved by adding it at the time of cutting.

A poorly soluble phosphate salt, an anionic surfactant, and ethylenediaminetetraacetic acid chelate-1 initially present in the reaction system.
The accumulation of carbon dioxide is an important factor for the vinyl polymer particles obtained, and the cap is appropriately determined within the above range depending on the particle size of the target vinyl polymer particles. For example, in order to increase the desired particle size, the amount of poorly soluble phosphate initially present in the reaction system is reduced by 1°, or the amount of anionic surfactant is increased. In order to reduce the target particle size, the opposite may be used. The poorly soluble phosphate salt added during the reaction is added once or in two or more portions. The timing of addition is such that the polymerization conversion rate of the vinyl monomer is between 20*#% and 60%, preferably 255%.
The weight part is between 60 and f%. This is because the final particle size of the vinyl polymer particles is determined at this stage, so sparingly soluble phosphate is added.

The beads are prevented from growing beyond the target particle size. Furthermore, the sparingly soluble phosphate salt added during the above reaction is added after the ethylenediaminetetraacetic acid chelate is added.

Note that the polymerization conversion rate can be measured by, for example, gas chromatography, specific gravity liquid method, or the like.

Examples of the present invention are shown below. In the example.

"Part" means 1 part by weight.

Example 1 1.5 tertiary calcium phosphate in a 3t separable flask
m, 5 parts of an aqueous solution of sodium dodecylbenzenesulfonate and 0.02 parts of iron ethylenediaminetetraacetate.
1 part was dispersed and dissolved in 1000 parts of distilled water. A solution of 2.5 parts of benzoyl peroxide dissolved in 1000 parts of styrene was added to this with stirring, and the temperature was raised to 90°C to initiate polymerization. Then, when the polymerization rate reached 40 to 50% by weight, 0.5 parts of tribasic calcium phosphate was added, and the mixture was directly reacted at 90 DEG C. for 8 hours to obtain 9 polymer particles.

Example 2 2M combined particles were obtained in the same manner as in Example 1, except that the amount of iron ethylenediaminetetraacetate was changed to 0.1 part.

Example 3 Example 1 except that 0.2 part of ethylenediaminetetraacetic acid calcium/um was used as the ethylenediaminetetraacetic acid chelate.
Polymer particles were obtained in the same manner as above.

9- Comparative Example 1 Example 1 except that iron ethylenediaminetetraacetate was not used.
In the same manner as above, 9 polymer particles were obtained.

Comparative Example 2 Polymer particles were obtained in the same manner as in Example 1, except that benzoyl peroxide was changed to 3 parts and iron ethylenediaminetetraacetate was not used.

The particle size distribution of the polymer particles obtained in each of the above Examples and Comparative Examples is shown in the following table.

Table 1 Particle size distribution (coefficient 1) i! I) Cut A: Pass through 5 meshes (4,00 meters), pass 78 meshes (238 meters), and pass 10-10-mm. C cut: Passes through 12 meshes (1.41 mm) and 20
D-cut = 20 without passing mesh (0, 84m) passing mesh (o, s4) and 28
Particles that do not pass through a mesh (0,59mm) E: 28 meshes (0,59mm) F that do not pass through a 42 mesh (o, a 5rran) Fine particles: Those that pass through a 42 mesh (0,35+nm) According to the invention, flexible vinyl polymer particles having a particle size distribution of 9 can be obtained by subjecting a vinyl polymer to aqueous suspension polymerization. Therefore 1 example.

When used as expandable particles, the utilization rate of beads is improved.

10-

Claims (1)

[Claims] 1. When carrying out suspension polymerization of a vinyl monomer in the presence of a sparingly soluble phosphate and an anionic surfactant, the vinyl monomer is 0,001 heavy weights of ethylenediaminetetraacetic acid chelate was added to the compound I, and after the addition of the ethylenediaminetetraacetic acid chelate, the polymerization conversion rate of the vinyl monomer was 20 times 1%. A method for producing vinyl spinning wheel combined particles, which comprises adding a sparingly soluble phosphate to the polymerization system at least once to 60% by weight to advance the polymerization.