JPS62161843A - Production of colored expandable styrene resin bead - Google Patents

Abstract

PURPOSE:To obtain the titled resin particle capable of giving a molded article resistant to the falling off of dye and having freely adjustable color tone and color density, by coating a styrene resin with a dye, dispersing the coated resin in an aqueous medium and impregnating a highly volatile foaming agent in the resin. CONSTITUTION:A styrene resin particle is mixed together with 0.001-0.5(wt)% dye (e.g. monoazo dye). Prior to, during or after the above process, 0.01-1% plasticizer (e.g. dioctyl phthalate) is added to the system and stirred. The styrene resin particle coated with the dye is dispersed in an aqueous medium and added with a highly volatile foaming agent (e.g. propane, butane, etc.) to effect the impregnation of 3-10% foaming agent in the resin particle.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing bi-colored expandable styrenic resin particles.

(Prior Art) Conventionally, the methods for obtaining colored expandable polystyrene beads include 1) mixing dyes or pigments with expandable polystyrene beads, followed by subsequent foaming and molding, and 2) forming polystyrene beads into cores. As.

After impregnating this with an organic solvent containing a dye, or.

A known method is to impregnate this with a monomer containing a dye and then impregnate it with a blowing agent during or after polymerization to obtain colored expandable polystyrene peas.

(Problems to be solved by the invention) However, these methods have advantages and disadvantages.
Improvement is required.

For example, in method 1), dyes and pigments adhered poorly to expandable polystyrene beads, and were detached, contaminating the pre-foaming machine. A high concentration of dye has the disadvantage of inhibiting fusion during molding. In method 2), the dye is decolorized by a polymerization catalyst, so the number of dyes is limited, and when the dye is dissolved in a solvent and impregnated, there are restrictions on solubility and concentration, and it is possible to use any amount of any dye. The disadvantage is that it cannot be impregnated with. Due to these drawbacks, the commercial value of expanded polystyrene molded articles colored by conventional methods is reduced.

Also, it was not possible to develop freely.

Accordingly, one object of the present invention is to provide colored expandable polystyrene beads that can freely select the color tone and adjust the degree of a when molded into a molded product, and that do not cause detachment of the dye.

(Means for Solving the Problems) The present invention involves dispersing dye-coated styrenic resin particles in an aqueous medium, adding an easily volatile foaming agent,
The present invention relates to a method for producing colored expandable styrenic resin particles characterized by impregnation.

What are styrenic resin particles used in the present invention?

Polystyrene or a copolymer whose main component is styrene (preferably styrene is 50% by weight or more), which is in the form of particles such as bispheres or pellets, especially true spherical particles obtained by suspension polymerization. preferable. Examples of monomers to be copolymerized with styrene include acrylic esters such as acrylonitrile and butyl acrylate, and methacrylic esters such as methyl methacrylate and cetyl methacrylate.

There are styrene derivatives such as α-methylstyrene and t-butylstyrene. The styrenic resin particles may be manufactured in one step using a known method.

The above-mentioned dyes may be oil-based dyes2. For example, monoazo dyes, anthraquinone dyes, disazo dyes,
There are perinone dyes, phthalocyanine dyes, etc. The amount of dye used is from 0.001 to 0.001 to styrene resin particles.
0.5% by weight is preferred.

If the amount of dye used is too small, the coloring effect will be small.
If the amount is too large, it becomes difficult to fix the entire amount to the styrene resin particles.

Dye coating can be carried out by stirring the styrenic resin particles in the presence of the dye, and it is particularly preferable to use a high-speed rotary mixer such as a Henschel mixer and stir by mechanical force accompanied by frictional heat.

The dye-coated styrenic resin particles are preferably styrenic resin particles coated with a dye and a plasticizer. For this purpose, it is preferable to add a plasticizer before or during the stirring in coating the dye, or to add the plasticizer after coating the dye and stirring in the same manner.

The plasticizer is preferably a substance that is a poor solvent for both dyes and styrene resin particles, such as phthalate esters such as dioctyl phthalate and dibutyl phthalate, and adipic esters such as dioctyl adipate.
The amount used is 0.01 to 1 weight per styrene resin particle.
Jk chi is preferable.

If the amount of plasticizer used is too small, the effect of improving dye fixation will be small, and if it is too large, the beads will aggregate and become difficult to handle.

In the present invention, styrenic resin particles whose surfaces are coated with a dye are dispersed in an aqueous medium and impregnated with a blowing agent.

A water-soluble polymer colloid, a 1a-soluble phosphate, etc. are present in an aqueous medium. Examples of water-soluble polymer colloids include cellulose derivatives such as polyvinyl alcohol, alkyl cellulose, hydroxyalkyl cellulose, and carboxyalkyl cellulose. In addition, examples of poorly soluble phosphates include tricalcium phosphate, magnesium phosphate, and the like.

The dispersant is preferably used in an amount of 0.1 to 1% by weight based on the styrene resin particles.
It is preferable to use os to 0.5% by weight.

Before dispersing the above-mentioned styrene-based resin particles whose surfaces are coated with a dye in an aqueous medium and impregnating them with a blowing agent, a styrene-based resin solvent such as toluene, ethylbenzene, xylene, or styrene is added to the aqueous medium. Preferably, the mixture is added and stirred.

This can promote adsorption or absorption of the dye onto the styrene resin particles. The solvent is preferably used in an amount of 0.1 to 2.0% by weight based on the styrene resin particles.

If the amount of the solvent is too small, the above effects will not be obtained, and if the amount is too large, the foaming properties will be likely to be impaired. Also, at this time, 70 to 130
It is preferable to carry out heating to ℃ in order to ensure the above-mentioned effect.

Easily volatile blowing agents include aliphatic hydrocarbons having a boiling point lower than the softening point of styrene resin particles.

For example, propane, butane, pentane, hexane, etc. can be used. In addition, 2 as a foaming aid.

Solvents for styrenic resin particles can also be used, such as alicyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as toluene, ethylbenzene, xylene, and styrene. As a foaming aid.

A solvent for dye adsorption or absorption can be used subsequently in the two-blowing agent impregnation step.

Impregnation with a readily volatile foaming agent 2 An easily volatile foaming agent can be added to an aqueous medium in which styrene resin particles whose surfaces are coated with a dye are dispersed, preferably by being press-injected. Impregnation with the blowing agent.

Preferably, the temperature is 65 to 110°C.

The easily volatile blowing agent is 3 to 10% of the styrene resin particles.
Preferably it is impregnated with 3ii%. Also 1
When the foaming aid is used, it is preferably added to the aqueous medium in an amount of 0.1 to 3]ii% based on the styrene resin particles.

After the impregnation with the easily volatile blowing agent is completed, the desired colored expandable styrenic resin particles are separated from the aqueous medium, optionally washed with water, dried, and used.

The bi-colored expandable styrenic resin particles may be coated with an antiblocking agent (eg, metallic soap, etc.) before use.

(Function) In the present invention, at the time of impregnation with the blowing agent 9, the dye present near the surface of the styrenic resin particles is accompanied by the blowing agent and penetrates into the inside of the particles. As a result, the white density of the dye particle has a concentration gradient such that it is high on one surface and becomes thin at the center.

As mentioned above, the dye has a high concentration near the surface and also penetrates into the interior, so it is possible to color the material in a deeper color with a smaller amount of dye.

Furthermore, by combining two various dyes, color tone can be easily selected.

(Example) Next, the present invention will be explained in detail based on examples.

The present invention is not limited to this.

Example 1 Internal volume 101! Henschel mixer with a particle size of 0.7
Polystyrene beads 50009 obtained by suspension polymerization with ~1.2 cylinders and a molecular weight of about 3.0 x 10 and Diamond Resin Blue P (trademark, manufactured by Mitsubishi Kasei Corporation) 20 as a dye.
9 and mixed at 2000 fpm for 1 minute, then 5 g of dioctyl adipate was added.

Mix again for 2 minutes to produce blue colored polystyrene beads.

Next, in an autoclave with an internal volume of 12 J and equipped with stirring blades,
．． Add 3% polyvinyl alcohol sooog and the polystyrene beads 50009 mentioned above.

Stirring was performed. At room temperature, add 30g of toluene.

The temperature was raised to 120°C in 120 minutes. After raising the temperature, the temperature was maintained for 120 minutes to allow the dye to be adsorbed onto the surface of the polystyrene beads. After that, it was cooled to 100°C, and 100 g of W-gocyclohexane and 600 m of butane gas were introduced under pressure.
After keeping the temperature for 4 hours, it was cooled to 40°C.

After removal from the autoclave at 40° C., 7.5% by weight of dehydration was obtained. To this, 0.1% by weight of zinc stearate and 0.1% by weight of stearic acid triglyceride were mixed in a blender and adhered to the bead surface to obtain colored expandable polystyrene beads.

After pre-foaming the obtained colored expandable polystyrene beads,
When foam molding was carried out at a magnification of 50 times, a uniformly colored molded product was obtained with good surface finish and internal fusion. Note that there was no desorption of the dye after the pre-foaming step.

Example 2 The mixer used in Example 1 had a particle size of 0.4 to 0.6
5,000 g of polystyrene beads and Sumiplast Orange HRP (manufactured by Sumitomo Chemical Co., Ltd.) o959 as a dye were added and stirred at 2,000 rpm for 2 minutes to obtain orange-colored polystyrene beads.

Next, 0.4% by weight of tricalcium phosphate and dodecylbenzene were added to the autoclave used in Example 1, and the temperature was raised to 90° C. over 60 minutes while stirring.

After holding for 10 minutes, normal pentane 2009゜LPG4
00ml! was press-fitted, kept warm for 4 hours, and then cooled to 40°C.

After taking it out from the autoclave at 40°C, it was dehydrated, washed, and dried to obtain expandable polystyrene beads colored orange. In contrast, zinc stearate 0.1
When 5% by weight was mixed, and after pre-foaming, foam molding was carried out into a cup at a magnification of 10 times, a uniformly colored molded product was obtained, and the molded product had good surface finish and internal fusion.

Further, there was no desorption of the dye after pre-foaming.

Example 3 Polystyrene beads 50009 with a particle size of 1.0 to 1.4 circles were added to the mixer used in Example 1. and Plast Yellowna 8040 (Arimoto Kagaku) as a dye 2.09. Guillen Blue FSNO488 (manufactured by Inu Nippon Ink) t, s
After stirring for 2 minutes, 4 green colored polystyrene beads were added.

Next, in the autoclave used in Example 1, dispersion 50009 containing 0.1% by weight of tricalcium phosphate, 0.3% by weight of calcium carbonate, and 0.012% by weight of dodecylbenzenesulfonic acid sorter and the colored polystyrene beads so
Add ethylbenzene 159 at room temperature while stirring.
was added and the temperature was raised to 100°C in 90 minutes. 30 at 100℃
After keeping warm for 1 minute, normal hexane 1009. Butane 600
rnl was press-fitted, and the mixture was further kept warm for 5 hours and then cooled to 40°C.

After pouring out the autoclave at 40°C, the beads were dehydrated, washed and dried, and the beads were treated with 0.0% zinc stearate.
1% by weight of stearamide, 0.1% by weight of stearic acid triglyceride, and 0.05% of stearic acid triglyceride were coated to obtain green expandable polystyrene beads.

After pre-foaming the obtained green expandable polystyrene beads,
When foam molding was performed at a magnification of 5 times, a molded product was obtained which was uniformly colored, had a good surface finish, and had good internal fusion.

Moreover, there was no desorption of the dye.

Example 4 Into the mixer used in Example 1, polystyrene beads 50009 with a particle size of 0.7 to 1.2 mm and Sumiplast Black H3B (manufactured by Sumitomo Chemical) 59 as a dye were added and mixed for 1 minute, followed by 2.5 g of dioctyl phthalate. was added and mixed again for 1 minute to obtain gray colored polystyrene beads.

Next, 5000gt of 0.4wt polyvinyl alcohol aqueous solution was placed in the autoclave used in Example 1.
The temperature was raised to 100°C in 0 minutes. After keeping the temperature at 100°C for 10 minutes, 500 cc of butane was injected, and after keeping the temperature for an additional 4 hours, it was cooled to 40°C.

After removing the beads from the autoclave at 40°C, they were dehydrated, washed and dried, and the beads were treated with 0.0% zinc stearate.
1% by weight of stearic acid triglyceride and 0.08% by weight of stearic acid triglyceride were sprinkled thereon to obtain expandable polystyrene beads colored gray. When this was foam-molded at a magnification of 15 times, a uniformly colored molded product was obtained with good surface finish and internal fusion.

Moreover, there was no desorption of the dye.

Comparative Example Uncolored expandable polystyrene beads (HiBeads 5SB-TK manufactured by Hitachi Chemical Co., Ltd.) were sprinkled with 0.07% by weight of Dyren Blue FSN 0488 to obtain blue expandable polystyrene beads. After pre-foaming this, 50
When foam molding was carried out at a double magnification, some of the dye was removed during the pre-foaming process, and the pre-foamer was stained blue.

Moreover, the obtained molded product had some color unevenness and was inferior in commercial value.

(Effects of the Invention) By using the colored expandable styrenic resin particles obtained by the present invention, a molded product with good surface finish and internal fusion can be obtained, and its color tone and density can be freely selected from a wide range. A molded article with high commercial value can be obtained.

Agent Patent Attorney Kuni Wakabayashi Aji (,”’:,’

Claims (1)

[Claims] 1. Production of colored expandable styrenic resin particles characterized by dispersing dye-coated styrenic resin particles in an aqueous medium and adding and impregnating them with an easily volatile foaming agent. Law. 2. Styrenic resin particles coated with dye,
The method for producing colored expandable styrenic resin particles according to claim 1, wherein the styrenic resin particles are coated with a dye and a plasticizer. 3. Production of colored expandable styrenic resin particles according to claim 1 or 2, in which a styrenic resin solvent is added to an aqueous medium and stirred before adding the easily volatile blowing agent. Law.