JPS6052165B2 - Manufacturing method of vinyl polymer particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for obtaining vinyl polymer particles with a narrow particle size distribution by suspension polymerization of vinyl monomers.

Generally, polymer particles produced by suspension polymerization are polymerized particles of at least one type of vinyl monomer that are dispersed in water by stirring and the action of a suspending agent (dispersing agent). Generated by.

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, with vinyl monomers mainly composed of styrene, L4-
It is known that the i-portion τ, ε--5-.1111-.--■-' is a sparingly soluble phosphate salt, and an anionic surfactant is used as a suspension aid.

Specifically, calcium kingate phosphate and sodium dodecylbenzenesulfonate 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 3 wgn, and the particle size distribution was wide. Conventionally, it has been possible to arbitrarily control the particle diameter of polymer particles by mechanical factors such as suspending agent concentration and stirring effect. However, it has been extremely difficult to narrow the particle size distribution of polymer particles. The polymer particles mainly composed of styrene obtained by suspension polymerization are impregnated with a blowing agent (eg, propane, butane, pentane, etc.) to obtain the desired expandable polystyrene resin. The uses of expandable polystyrene resin can be divided into the following three fields depending on the particle size. That is, (
1) Expandable polystyrene particles with a particle size of approximately 300p to 700μ are suitable for cups such as in-stat foods, (2) particles with a particle size of approximately 700μ to 1800μ are used for various types of packaging and fish boxes, (3) particles Diameter approximately 1500μ to 300
0μ ones are used for ports for building materials, etc. Due to these differences in use, the required properties of expandable polystyrene also differ, so it is necessary to manufacture expandable polystyrene for each purpose, but the polymer particles obtained by suspension polymerization have a wide particle size distribution. and it is difficult to achieve that goal. The present invention solves these problems.

That is, the present invention provides styrene or its derivatives (
4) When carrying out aqueous suspension polymerization of vinyl monomers containing at least 0.001% by weight of the vinyl monomers, before the start of polymerization or until the polymerization conversion rate is 3% by weight, Ethylenediaminetetraacetic acid chelate is added, and after the addition of ethylenediaminetetraacetic acid chelate, a sparingly soluble phosphate is added to the polymerization system between the polymerization conversion rate of the vinyl monomer of 2% by volume and 6% by volume. This invention relates to a method for producing vinyl polymer particles, which is characterized by adding the particles one or more times to advance polymerization.

Examples of the vinyl monomer in the present invention include styrene, α
- Styrene derivatives such as methylstyrene, vinyltoluene, valachlorstyrene, acrylonitrile, acrylic acid ester, methacrylic acid ester, vinylpyridine, vinylcarbazyl, butadiene, etc. Among these vinyl monomers, styrene or styrene derivatives are 5% or more of saliva is used.

Slightly soluble phosphates include tricalcium phosphate, magnesium phosphate, etc., and have a submicron size of 0.
Sizes between 2 and 0.05 microns are useful.

The total amount of poorly soluble phosphate used is 0.01% by weight or more based on the total amount of substances present in the polymerization system, and there is no particular upper limit, but if it exceeds 1% by weight, it exceeds the necessary amount. It will be wasted. Preferably 0.05-0.5% by weight
used. If the amount is less than 0.01% by weight, the particle size distribution of the produced polymer particles cannot be narrowed.

The amount of the sparingly soluble phosphate initially present in the reaction system is not particularly limited within the above range, but it is preferably used from 1 to 3 of the total amount of the sparingly soluble phosphate. Examples of anionic surfactants include alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, alkyl sulfonates in which SO3Na is added directly to an alkyl group, β-tetrahydronaphthalene sulfonates in which SO3Na is added to naphthalene, and N-isopropyl. Acid sulfonates such as sodium cyclohexyl acid sulfonate,
Higher fatty acid salts such as sodium oleate, dialkyl sulfosuccinates such as di-2-ethylhexyl sodium sulfosuccinate, and the like 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 0.0% by volume based on the total volume, It is preferably in the range of 0.001 to 0.01% by weight. 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 ethylenediaminetetraacetic acid. Nickel, barium ethylenediaminetetraacetate, magnesium ethylenediaminetetraacetate, manganese ethylenediaminetetraacetate, etc.

These ethylenediaminetetraacetic acid chelates may be used alone or in combination. The amount of these used is 0.0001% by weight or more based on the monomer.

If the amount is less than 0.0001% by weight, the particle size distribution of the produced polymer particles cannot be narrowed.

Further, even if it is used in an amount exceeding 0.05% by weight, no increase in the effect can be expected, so 0.05% by weight or less is sufficient.The timing of addition of ethylenediaminetetraacetic acid chelate is before the start of suspension polymerization; Or early stage is preferable.

In particular, narrowing the width of the particle size distribution can be achieved by adding it when the polymerization conversion rate is 3% or less. The amounts of poorly soluble phosphate, anionic surfactant and ethylenediaminetetraacetic acid chelate initially present in the reaction system are important factors for the resulting vinyl polymer particles.
The amount is appropriately determined within the above range C depending on the particle size of the target vinyl polymer particles. For example, in order to increase the desired particle size, first reduce the amount of poorly soluble phosphate present in the reaction system or increase the amount of anionic surfactant. 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 2% by weight and 6% by weight, preferably between 25% by weight and 6% by weight. This is because the final particle size of the vinyl polymer particles is determined at this stage, so a sparingly soluble phosphate is added to prevent the beads from growing beyond the desired particle size. Furthermore, the sparingly soluble phosphate salt added during the above reaction is added after the ethylenediaminetetraacetic acid chelate is added. The polymerization conversion rate can be measured, for example, by gas chromatography, specific gravity liquid method, or the like.

Examples of the present invention are shown below.

In the examples, 1 part means 1 part by weight.

Example 1 31 tertiary calcium phosphate in a separable flask 1. 5 parts of a 1% aqueous solution of sodium dodecylbenzenesulfonate and 0.0 parts of iron ethylenediaminetetraacetate. The ingredients were dispersed and dissolved in 10(1) parts of distilled water.

To this, add 2.5 parts of benzoyl peroxide to 10(4) parts of styrene.
The solution was added with stirring, and the temperature was raised to 90°C to start polymerization. Then, when the polymerization rate reached 40 to 5%, 0.5 part of tribasic calcium phosphate was added,
Polymerization was continued at 90°C for 8 hours to obtain polymerized particles.
Example 2 Polymer 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 Polymer particles were obtained in the same manner as in Example 1, except that 01 part of calcium ethylenediaminetetraacetate was used as the ethylenediaminetetraacetic acid chelate.

Comparative Example 1 Polymer particles were obtained in the same manner as in Example 1 except that iron ethylenediaminetetraacetate was not used.

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.

According to the present invention, vinyl polymer particles with a narrow particle size distribution can be obtained by subjecting vinyl monomers to aqueous suspension polymerization.

Claims (1)

[Claims] 1. When carrying out suspension polymerization of a vinyl monomer containing 50% by weight or less of styrene or its derivatives in the presence of a poorly soluble phosphate and an anionic surfactant, before the start of polymerization or at a polymerization conversion rate of up to 30% by weight. During this period, 0.001% by weight or more of ethylenediaminetetraacetic acid chelate is added to the vinyl monomer, and after the addition of the ethylenediaminetetraacetic acid chelate, the polymerization conversion rate of the vinyl monomer is 20
Between 1% and 60% by weight, 1% of poorly soluble phosphate is added to the polymerization system.
A method for producing vinyl polymer particles, which comprises adding the particles more than once to advance polymerization.