JPS5848577B2 - Method for manufacturing expandable styrenic resin particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing colored expandable styrenic resin particles.

Conventionally, in order to color expandable styrenic resin particles, a method has been used in which the particles are mixed with a dye or pigment, and the surfaces of the particles are coated with the dye or pigment.

However, this method had the following drawbacks.

1) The adhesion of dyes and pigments to resin is incomplete, and they come off and contaminate the pre-foaming machine, etc.

2) It is not possible to color the inside of the resin.

3) Inhibits fusion.

4) Coloring tends to be uneven.

Due to these drawbacks, expandable styrenic resin particles colored by conventional methods have low commercial value.

The present invention solves these problems.

That is, in the present invention, styrene resin particles are dispersed in an aqueous medium, a dye is dissolved or dispersed in a vinyl monomer, and the vinyl monomer is polymerized, and foaming is performed during or after the polymerization. The present invention relates to a method for producing expandable styrenic resin particles, which is characterized by impregnating them with an agent.

In the present invention, first, styrenic resin particles are dispersed in an aqueous medium.

This can be achieved by dispersing already produced styrene resin particles in an aqueous medium.

The styrenic monomer may also be polymerized in suspension in an aqueous medium, in which case the weight does not have to be complete.

In the present invention, the dye is dissolved or dispersed in a vinyl monomer and added to an aqueous medium.

The dye should be added when the polymerization amount, including the styrene resin already present, is 50% by weight based on the total of the styrene resin and styrene monomer existing in the aqueous medium and the newly added vinyl monomer. % or more.

When the amount is less than 50% by weight, the dye inhibits polymerization, which is not preferable.

When the dye is added at 50% by weight or more, there is no practical problem even if polymerization is inhibited.

In the present invention, styrene resin refers to styrene or α
- Homopolymers or copolymers of styrene derivatives such as methylstyrene, chlorostyrene, vinyltoluene, acrylic acid esters such as ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, methacrylic acid Examples include copolymers of one or more monomers such as methacrylic esters such as cetyl, acrylonitrile, vinyl chloride, and divinylbenzene, and styrene or styrene derivatives.

The styrene resin preferably contains 50% by weight or more of styrene or a styrene derivative.

In the present invention, the styrenic resin particles are particles such as spherical particles and pellets of the above-mentioned styrene resin, and spherical particles obtained by suspension polymerization are preferable.

In the present invention, the dyes include monoazo dyes, pericyclic dyes,
All dyes such as perinone, anthraquinone, disazo, thioindigo, and phthalocyanine dyes can be used.

As the vinyl monomer for dissolving or dispersing the dye, any material that can be used as a raw material for the above-mentioned styrene resin can be used, but it is preferable to use 50% by weight or more of styrene or a styrene derivative as the vinyl monomer.

A portion of the vinyl monomer may be added without dissolving or dispersing the dye.

The dye is preferably used in an amount of 0.001 to 1% by weight based on the resin component in the finally obtained expandable styrenic resin particles.

If it is less than 0.001% by weight, the coloring effect will be reduced, and if it exceeds 1% by weight, dispersion during suspension polymerization will become unstable.

In the above suspension polymerization, a sparingly soluble phosphate as a dispersant,
Water-soluble polymeric protective colloids and the like can be added to the polymerization system.

Examples of sparingly soluble phosphates include tricalcium phosphate and magnesium phosphate.

As a polymeric protective colloid, polyvinylalconotz
, water-soluble cellulose derivatives such as alkylcellulose, hydroxyalkylcellulose, and carboxyalkylcellulose, and sodium polyacrylate.

The amount of poorly soluble phosphate is 0 based on the total amount of substances present in the polymerization system.
．． 01% by weight or more, water-soluble polymer protective colloid is 1 to 0
．． It is preferably used in a range of 0.001% by weight.

In addition, anionic surfactants and water-soluble inorganic salts can be added to the polymerization system.

Polymerization initiators suitable for use in the process of the invention include benzoyl peroxide, dichlorobenzoinole peroxide, dicumyl peroxide, di-tertiary butyl peroxide, 2,5-di(beroxybenzoate)hexyne- 3, 1. 3-bis(tert-butylpert-t-cyisopropyl)benzene, lauroyl peroxide, tert-butylperacetate, 2,5-dimethyl-2,5-(tert-butylperacetate)
organic peroxides such as 3,2,5-dimethyl-2,5-di(tertiary butylperoxy)hexane and tertiary butylperbenzoate, methyl ethyl ketone peroxide, methyl cyclohexanone peroxide, azo There are ab-based compounds such as bisisobutyronitrile and dimethylazodiisobutyrate, and one or more of these can be used.

The amount used is determined by the type of vinyl monomer and the desired molecular weight of the resulting polymer;
It is preferably used in an amount of 0.1 to 4.0% by weight based on the vinyl monomer.

The polymerization initiator is preferably added dissolved in the vinyl monomer.

The blowing agent used in the present invention has a boiling point lower than the softening point of the resin to be produced, and has the property of not dissolving vinyl resin particles or causing them to swell slightly.

Examples of such blowing agents include aliphatic hydrocarbons such as propane, butane, and pentane, cyclic aliphatic hydrocarbons such as cyclobutane and cyclopenkune, and halogenated hydrocarbons such as methyl chloride and dichlorodifluoromethane. Can be done.

The amount of the blowing agent used is 1 to 20% by weight based on the weight of the expandable vinyl polymer particles.

Among the above blowing agents, when propane and butane are used alone or in combination, it is preferable to use a small amount of an organic solvent that dissolves the vinyl polymer during impregnation with the blowing agent.

Examples of such solvents include ethylene dichloride, trichloroethylene, tetrachloroethylene, benzene, toluene, xylene, ethylbenzene and the like.

Impregnation with a blowing agent can be carried out by adding a blowing agent to an aqueous medium during polymerization, or by adding a blowing agent to a state in which the polymer particles are suspended in an aqueous medium after polymerization.

When adding a blowing agent during the polymerization, it is preferable to add the blowing agent after the conversion of the vinyl monomer reaches 50% by weight or more, from the viewpoint of stability of the polymerization system.

Example 1 0.4% polyvinyl alcohol aqueous solution was placed in an autoclave with an internal volume of 12 liters and equipped with a stirring blade. IO. 5～
3000 g of polystyrene particles with a diameter of 0.7 mm were added, and the temperature was raised to 90°C while stirring.

After impregnating 1,500 g of styrene monomer into polystyrene particles in three parts, 8 g of benzoyl peroxide and 2.5 g of tert-butyl perbenzoate were added to 30 g of styrene monomer.
(After it was dissolved in Bi' and added, it was kept warm for 3 hours, and the polymerization rate was 93%.

Dyren Blue FSNO488 (Inu Nippon Ink Chemical Industry ■ trade name, anthraquinone type) was selected as the dye 2.5
g was dissolved in 20 (l) of styrene monomer and added.

After keeping the temperature for another 1 hour, 100 g of cyclohexane and 401 g of butane were injected under pressure.

In order to complete the polymerization, the mixture was kept at 115° C. for 4 hours and then cooled to separate water and obtain expandable polystyrene uniformly colored blue.

The resulting expandable polystyrene was uniformly colored with the dye throughout, and there was no detachment of the dye.

Further, when pre-foaming was performed to form a molded product, there was no color unevenness and good fusion properties were exhibited.

Example 2 1.5 g of tricalcium phosphate and 0.0 g of sodium dodecylbenzenesulfonate were placed in an autoclave with a stirring blade having an internal volume of 4 liters.
Styrene monomer 80 (L9) in which 2.5 g of benzoyl peroxide and 0.5 g of perhexacyclopropane were dissolved was added. At this time, the polymerization rate was 60%.As a dye, 0.5 g of Plast Yellow 8040 (trade name of Arimoto Chemical) was dissolved in styrene monomer 201 and added.

After keeping warm for 4 hours, 20 g of cyclohexane and 80 g of butane were added. ? was press-fitted, kept at 110° C. for 2 hours, and then cooled.

The expandable styrenic resin particles thus obtained were uniformly colored yellow, and there was no desorption of the dye.

Further, when pre-foaming was performed and molding was performed, there was no color unevenness and good fusion properties were exhibited.

According to the present invention, expandable styrenic resin particles can be obtained that can be foamed into a uniformly colored molded article without detachment of the colorant.

Claims (1)

[Claims] 1 Dispersing styrene resin particles in an aqueous medium, adding a dye dissolved or dispersed in a vinyl monomer, polymerizing the vinyl monomer, and impregnating it with a blowing agent during or after polymerization. Production island of expandable styrenic resin particles characterized by