JPH02247234A - Production of expandable colored thermoplastic resin particle and colored expanded article - Google Patents

Abstract

PURPOSE:To obtain the subject particle giving a uniformly colored expansion- molded article having excellently finished surface, etc., by dispersing thermoplastic resin particles in an aqueous medium and adding a uniformly dispersed dye emulsion liquid and a highly volatile foaming agent to the dispersion to impregnate said dye and foaming agent into the particles. CONSTITUTION:The objective particle can be produced by dispersing thermoplastic resin particles in an aqueous medium and adding a uniformly dispersed dye emulsion liquid containing at least a part of the dye in a state dissolved in 0.1-5.0wt.% (based on the thermoplastic particle) of a solvent and a highly volatile foaming agent (e.g. propane or butane), thereby impregnating the dye and the foaming agent into the particles. The amount of the dye is preferably 0.001-0.5wt.% based on the thermoplastic resin particle. A colored expansion- molded article can be produced by pre-expanding and then molding the particles.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing expandable thermoplastic resin particles and a colored foamed molded article.

(Prior Art) Conventional methods for obtaining two colored expandable thermoplastic resin particles include (1) a method of mixing dyes or pigments into expandable thermoplastic resin particles;

(2) After impregnating thermoplastic resin particles with a dye-containing organic solvent, or impregnating them with a dye-containing monomer and impregnating them with a blowing agent during or after polymerization. 1. A method for producing colored expandable thermoplastic resin particles.

(3) A method is known in which the surface of thermoplastic resin particles is coated with a dye and then impregnated with a blowing agent to obtain colored expandable thermoplastic resin particles.

(Problem to be solved by the invention) However, 5. These methods have advantages and disadvantages,
Improvement is required.

For example, in method (1) above, the dye or pigment adheres poorly to the expandable polystyrene beads and comes off, contaminating the pre-expanding machine. It has the disadvantage of being a hindrance. In method (2), the dye is decolorized by a polymerization catalyst, so the dye is limited, and when dye is dissolved in a solvent and impregnated, there are restrictions on solubility and concentration, and any dye can be It has the disadvantage that it cannot be impregnated in large quantities. Although method (3) allows any material to be impregnated in any amount, it requires an additional step of coating the thermoplastic resin surface with dye.
It had the disadvantage of being less economical.

Therefore, due to these drawbacks, molded products obtained from colored expandable thermoplastic resin particles produced by conventional methods have problems such as reduced commercial value and inability to develop freely. Ta.

Therefore, the present invention is directed to colored foamable thermoplastic resin particles that can freely select the color tone and adjust the density when molded into a molded product, and that do not cause dye desorption, and colored foamed resin particles obtained using the same. Molded products.

The purpose is to provide it more economically.

(Means for Solving the Problems) The present invention involves dispersing thermoplastic resin particles in an aqueous medium, and then dispersing at least a portion of the dye with a solvent of 0.1 to 5.0% by weight relative to the thermoplastic resin particles. A method for producing colored expandable thermoplastic resin particles, which comprises adding a dissolved, nine-dimensional dye-dispersed emulsion and an easily volatile blowing agent to impregnate the dye and easily volatile blowing agent into the thermoplastic resin particles. , and a method for producing a colored foam molded article using the obtained colored expandable thermoplastic resin particles.

The thermoplastic resin particles used in the present invention are particles of thermoplastic resin such as spheres, pellets, etc.
Particularly preferred are true spherical particles obtained by suspension polymerization.

The thermoplastic resin cage is mainly composed of polystyrene or styrene (preferably 50% by weight of styrene).
Copolymers containing the above are preferred. Monomers to be copolymerized with styrene include acrylic esters such as acrylonitrile and butyl acrylate, methacrylic esters such as methyl methacrylate and cetyl methacrylate,
Examples include styrene derivatives such as α-methylstyrene and t-7'' tylstyrene, and maleic anhydride.In addition, thermoplastic resins include homopolymers and copolymers containing methacrylic acid ester as a product, polyethylene, and polypropylene as main components. Polyolefins and the like can also be used.

In the present invention, the dye that is the coloring agent is preferably an oil-based dye. Examples include monoazo dyes, anthraquinone dyes, disazo dyes, perinone dyes, and thalocyanine dyes.

The amount of dye used is from 0.001 to thermoplastic resin particles.
0.5% by weight is preferred. If the amount of dye used is too small, the coloring effect will be small, and if it is too large, it will be difficult to completely impregnate the resin particles with the dye. Not only can it not be used effectively, but wastewater treatment requires a large amount of cost.

In the present invention, these dyes are used as a uniform dye dispersion emulsion by dispersing them in a small amount of a solvent that dissolves at least a portion of the dyes, forming a dye dispersion, and emulsifying this. If the dye dispersion emulsion is not uniform, color unevenness will occur in the colored beads obtained. In addition, the homogeneous dye dispersion emulsion means that the emulsion dispersed particles in the liquid are preferably 1 μm to 10 μm.
The liquid has a particle size of 0 μm. Particle size is 100μm
If it exceeds, it becomes difficult to obtain a uniform dye dispersion emulsion. The solvent is fine as long as it has the property of dissolving the dye, but benzene, toluene, and xylene are particularly suitable.

Preferably, one or more aromatic hydrocarbons are selected from aromatic hydrocarbons such as styrene and benzyl alcohol.

The amount of solvent is based on the thermoplastic resin particles.

0.1 to 5.0% by weight. If it is less than 1ite, the uniformity of dye dispersion when making a dye dispersion emulsion will be poor.

If the amount exceeds &O by weight, the quality of the colored expandable thermoplastic resin particles will be adversely affected, and therefore it cannot be used.

Emulsification of dye dispersion involves an aqueous solution containing an emulsifier.

It can be prepared by adding the dye dispersion while dispersing it, preferably with a homomixer.

Dispersion and emulsification using a homomixer has the function of crushing insoluble dyes, and makes a uniform emulsion, especially when using dyes that are not in fine powder form or when toning colors using several types of dyes. becomes possible.

As a result, it becomes useful for uniformly coloring the thermoplastic resin particles. In addition, even if it is something other than a homo mixer.

Any material that can produce a similar uniform dye dispersion emulsion can be used.

As an emulsifier for preparing an emulsion, a polymer compound that easily forms a protective colloid is preferable. For example, polyvinyl alcohol, polyvinylpyrrolidone.

Hydroxyethyl cellulose, carboxymethyl cellulose, and the like may be used alone or in combination of two or more. Other ionic surfactants can also be used. The amount of emulsifier used is preferably 10 to 500 more by weight than the dye. If it is less than 10% by weight, it becomes difficult to maintain the dye dispersed, and if it exceeds 500% by weight, it is meaningless.

In the present invention, thermoplastic resin particles are dispersed in an aqueous medium, and a uniform dye dispersion emulsion obtained by the above method and an easily volatile blowing agent are added and impregnated. Polymeric colloid, 11-soluble phosphate, etc. are present in the aqueous medium. Examples of water-soluble polymer colloids include cellulose derivatives such as polyvinyl alcohol, alkyl cellulose, hydroxyalkyl cellulose, and carboxyalkyl cellulose.

In addition, poorly soluble phosphates include tricalcium phosphate,
Examples include magnesium phosphate.

The dispersant is 0.1 to 1% by weight based on the thermoplastic resin particles.
It is preferable to use When a sparingly soluble phosphate is used as a dispersant, it is preferable to simultaneously use an anionic surfactant such as sodium dodecylbenzenesulfonate in an amount of o, oos to 0.5% by weight based on the thermoplastic resin particles.

Easily volatile foaming agents used in the present invention include:

Aliphatic hydrocarbons 2 having a boiling point lower than the softening point of the thermoplastic resin particles, such as propane, butane, pentane, hexane, etc., or fluorocarbons such as Freon 11 and 7 Leon 12 can be used. Furthermore, alicyclic hydrocarbons such as cyclohexane can also be used as blowing aids.

The easily volatile blowing agent is 3 to 10% per thermoplastic resin particle.
Preferably, it is used so that it is impregnated in weight percent. Also 9
When a foaming aid is used, it is added in an amount of 0.1 to 3% by weight based on the thermoplastic resin particles in an aqueous medium.

Alternatively, it is preferable to add it to a dye dispersion emulsion.

Impregnation with a readily volatile foaming agent and a dye can be carried out by adding or pressurizing an easily volatile foaming agent and the dye dispersion emulsion into an aqueous medium in which thermoplastic resin particles are dispersed. The blowing agent and dye impregnation is preferably carried out at room temperature to 120°C.

After the impregnation of easily volatile blowing agents and dyes is completed.

The desired colored expandable thermoplastic resin particles are separated from the aqueous medium, optionally washed with water, dried, and then used.

Before use, apply an anti-blocking agent such as metal soap.

It may also be coated with colored expandable thermoplastic resin particles.

The colored expandable thermoplastic resin particles obtained as described above are pre-foamed by a conventional method and then filled into a mold for forming a colored foamed molded article.

The colored foamed molded product obtained is uniformly colored.

Fusion 9 has a good surface finish.

(Function) In the present invention, at the time of impregnation with a blowing agent, the dye uniformly dispersed in the aqueous medium is accompanied by the blowing agent, adsorbed onto the particle surface, and further penetrated into the inside. 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 described above, the dye has a high concentration near the surface and penetrates into the interior, so it is possible to color the material in a deeper color with less dye.

Furthermore, by combining two various dyes, the 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 Preparation of uniform dye dispersion emulsion> Sumiplast Blue OA (trademark, Sumitomo Chemical) was used as the dye.
) 39 was dispersed and dissolved in 7 g of toluene. This was placed in 200 g of a double 8% polyviny/I7 flucol aqueous solution being stirred with a homomixer, and stirring was continued for 10 minutes to prepare a uniform dye dispersion emulsion in which each dispersed particle had a particle size of about 10 to 100 μm. Note that the particle diameter of the two-dispersed particles was observed using a stereomicroscope.

<Impregnation of dye and blowing agent into resin particles> In an autoclave with an inner volume of 4E and equipped with a stirring blade, 1000 g of 0.3 weight tricalcium phosphate and 0.01 weight tS sodium dodecylbenzenesulfonate aqueous solution were placed.

10 polystyrene beads with a particle size of 0.7-1.0 am
I put in 009. Next, the above uniform dye dispersion emulsion was added while stirring.

Furthermore, after the cyclohexane 209 was pressurized, the temperature was raised to 80 °C for - minutes, and 30 minutes after the completion of heating, butane (iso/n -
4/6) 140cc was press-fitted. Further, after 30 minutes, the temperature was raised to 115°C over 60 minutes.

After holding for 5 hours, it was cooled to 40°C.

After removing from the autoclave at 40°C, they were dehydrated, washed and dried to produce expandable polystyrene beads uniformly colored deep blue (butane and cyclohexane content 7.
．． 3% by weight). At this time, the waste liquid was milky white and it was found that all the dye was impregnated into the expandable polystyrene beads. To this, 0.1% by weight of zinc stearate and 0.1% by weight of stearic acid triglyceride were sprinkled on the surface to obtain colored expandable polystyrene beads.

The obtained colored expandable polystyrene beads were pre-foamed to 50 mg/ml and then molded to give a uniformly colored foamed molded product with good surface finish and internal fusion.

Also, there was no desorption of dye into the pre-foaming machine or molding mold.

Example 2 The dye is Dyren Blue FSN-0488 (trademark).

Manufactured by Dainippon Ink Chemical ■) 0.49. Plast yellow 8
040 (trademark, manufactured by Arimoto Chemical ■) o, ag, and Sumiplast Black H3B (trademark, manufactured by Sumitomo Chemical ■) were changed to 0.1 g, but in the same manner as in Example 1.

Expandable polystyrene beads colored green were obtained.

The obtained green expandable polystyrene beads were heated at 40 m1/s.
When the product was pre-foamed and then molded, a uniformly colored foamed molded product was obtained with good surface finish and internal fusion.

Comparative Example 1 For uncolored expanded polystyrene beads (Hi-Beads 5SB-TK manufactured by Hitachi Chemical Co., Ltd.).

0.3% by weight of Sumiplast Blue OAt was coated with a Henschel mixer to obtain two colored expandable polystyrene beads. When this was pre-foamed at 50 g/g and then molded, the pre-foaming machine and the mold were significantly stained with blue color, and the foamed molded product had a pale blue color compared to Example 1.

Comparative Example 2 When making a dye dispersion emulsion in Example 2, a homomixer was not used and the dye and blowing agent were impregnated by mixing with a normal propeller blade.
00μm, it is impossible to make a uniform dye dispersion emulsion. The foamed molded product obtained using this product had color unevenness with scattered dark blue colors and was inferior in commercial value.

(Effects) As is clear from the above examples, according to the method of the present invention, when a foam molded product is made, it is uniformly colored, has a good surface finish, and has good internal fusion.

The color tone can be freely selected and the density can be adjusted, and colored expandable thermoplastic resin particles and colored expanded molded articles that do not cause detachment of dyes can be obtained more economically.

Claims (1)

[Claims] 1. After the thermoplastic resin particles are dispersed in an aqueous medium, at least a portion of the dye is dissolved by a solvent of 0.1 to 5.0% by weight based on the thermoplastic resin particles. A method for producing colored expandable thermoplastic resin particles, which comprises adding a uniform dye dispersion emulsion and an easily volatile blowing agent to impregnate the thermoplastic resin particles with the dye and the easily volatile blowing agent. 2. Add dye to thermoplastic resin particles by 0.001 to 0.5
The method for producing colored expandable thermoplastic resin particles according to claim 1, wherein the colored expandable thermoplastic resin particles are used in an amount of % by weight. 3. The method for producing colored expandable thermoplastic resin particles according to claim 1 or 2, wherein the uniform dye dispersion emulsion is prepared using a homomixer. 4. A method for producing a colored foam molded article, which comprises pre-foaming the colored expandable thermoplastic resin particles obtained by the production method according to claim 1, 2 or 3, and then molding.