JPS58204034A - Method for coloring expanded polystyrene particle - Google Patents

Abstract

PURPOSE:To obtain the titled particles for molding, which are uniformly colored without using any coating adhesives, by using a mixture of an alcohol and an org. solvent compatible with the alcohol and capable of dissolving polystyrene and a dye soluble in said mixture. CONSTITUTION:A mixture of 100pts.wt. alcohol which does not dissolve polystyrene, such as methanol, and 10-100pts.wt. org. solvent compatible with said alcohol and capable of dissolving polystyrene, such as toluene, is prepd. Expanded polystyrene particles are colored by using a dye bath consisting of said mixture and a dye soluble in said mixture, such as oil-soluble azo dye.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for coloring expanded polystyrene particles, and an object of the present invention is to provide a method for obtaining expanded polystyrene particles for molding whose surfaces are uniformly colored with a dye.

Expanded polystyrene particles are usually used to manufacture molded articles made of expanded polystyrene, and the expanded polystyrene particles contain a chemical foaming agent or hydrocarbon gas as a blowing agent. When producing colored foam-resistant molded products using these expanded polystyrene particles, first, the polystyrene is heated and melted, a coloring agent is kneaded into it to color it, and then the expanded polystyrene particles are mixed and molded. There is a method, but this method is complicated and expensive, and if a foaming agent with a low foaming temperature or foamed polystyrene particles containing gas is used, too much gas leaks out, making it impossible to obtain a good foamed molded product.

Another method is to apply a layer of pigment or dye to the surface of the expanded polystyrene particles using an adhesive, but this method prevents the adhesion layer on the particle surface from fusing the expanded polystyrene particles together during molding. This tends to result in brittle molded products.

The present inventors discovered that in order to achieve uniform coloring in a short time by simply immersing at room temperature without using any coating adhesives such as pigments or dyes, a combination of water and an organic solvent was used. A dye solution (hereinafter simply referred to as a dye bath) in which a dye is dissolved in a mixed solution (
! - I was inventive after knowing that the method used would solve the above-mentioned drawbacks (Patent No. 911153).

After further investigation, we found that the dye that had been dissolved in the previous invention precipitated or precipitated in some cases, forming an unrestricted layer, and as a result, it was difficult to dye with a strong # degree, which caused slight poor dyeability. I found out that sometimes. While proceeding with this improvement study, the present inventors found that by using a mixture of alcohol and an organic solvent in place of the mixture of water and organic solvent in the previous invention, precipitation and precipitation of the dye occurred. The inventors of the present invention have discovered that a uniform solution can be obtained without any problems, and a dye bath with a considerably high am. I was able to complete it.

That is, the gist of the present invention is to color expanded polystyrene grains by using a mixed solution consisting of alcohol and an organic solvent that is compatible with the alcohol and dissolves polystyrene, and a dye that is soluble in the mixed solution. The method of coloring expanded polystyrene particles is characterized by using a dye bath of:

The alcohol used in the present invention usually has 1 to 1 carbon atoms.
6, preferably 2 to 5, more preferably aliphatic alcohols. Specific examples include u, mer'/-l, ethanol, propa/-/l/, impropatol, butanol, imbutanol, tertiary butanol, alcohol, methyl cellosolve, methyl cellosolve, butyl cellosolve, etc. be able to.

In addition, examples of organic solvents that are compatible with alcohol and dissolve styrene include aromatic and aliphatic hydrocarbons and mixed liquids containing these as main components, such as badruene, xylene, benzene, gasoline, kerosene, ligroin, Tetralin,
Alkylbenzene, TV/oil, pine oil, liquid paraffin, etc., halogenated hydrocarbons, such as methylene chloride, chlorobenzene, chlorotoluene, fromhensen, chlorinated liquid paraffin, etc., ketones, such as methyl isobutyl ketone, methyl -〇-amyl ketone, methyl-〇-hexyl ketone, ethyl-〇-butyl ketone,
C-n-furovir ketone, acetophenone, etc., ethers such as inflovir ether, methyl phenyl ether, ethylpengel ether, furan, etc., and esters such as isopropyl acetate, butyl acetate, butyl propionate, citric acid ester, ricinol. In addition to acid esters, various phthalate esters, various oleate esters, various stearate esters, various adipate esters, various phosphate esters, various abietic acid esters, various benzoic esters, etc. can be mentioned.

These various solvents may be used alone or in combination.

Dyes soluble in the mixture of alcohol and organic solvent used in the present invention include azo oil-soluble dyes, anthraquinone oil-soluble dyes, amiazo dyes, aminoanthraquinone dyes, phthalocyanine dyes, etc. , these may be used alone or in combination of two or more.

In order to color foamed Boristyre/granules using these colorants, usually 0.1 to 10 parts (by weight, the same shall apply hereinafter) of the above dyes are mixed with 100 parts of alcohol, and A dyebath is prepared by dissolving 10 to 100 parts, preferably 20 to 60 parts, of the above-mentioned organic solvent for dissolving polystyrene in a mixed solution.

The obtained tomo dye bath is maintained at 10 to 40C, for example, the dye bath 10
Add 50 to 100 parts of expanded polystyrene grains to 0 parts.
After stirring for ~30 minutes, one expanded polystyrene granule is taken out of the dye bath and air-dried to easily obtain uniformly colored expanded polystyrene granules.

As described above, since the method of the present invention involves room-temperature treatment, there is no risk of foaming of the expanded polystyrene particles during the treatment, and since there is no adhesive for pigments or dyes on the surface of the expanded polystyrene particles, molding is possible. At this time, excellent colored molded products can be easily obtained without inhibiting the fusion between polystyrene particles.

It is extremely important to use a mixture of a solvent that does not dissolve the polystyrene particles and a solvent that dissolves them as the dyebath of the present invention.

The rationale for this is not clear, but only when the type and ratio of the solvent that dissolves the styrene grains and the solvent that does not dissolve the styrene grains meet certain conditions, the styrene grains can be dissolved without welding together. Experiments have confirmed that it is possible to dye the surface uniformly, strongly, and in varying shades.

If expanded polystyrene particles are immersed in a dye solution containing only a solvent that easily dissolves polystyrene, the surface of the particles will first soften and swell, and then the polystyrene will begin to dissolve and fall off.

As a result, the chemical blowing agent or hydrocarbon gas in the foamed polystyrene grains is exposed, which not only makes foam molding difficult, but also causes the polystyrene grains to weld together and some of the polystyrene grains to dissolve and flow out. Practical use is impossible due to these drawbacks.

Therefore, if a solvent that is a mixture of an alcohol that does not dissolve polystyrene and an organic solvent that dissolves polystyrene in a specific ratio is used as a dye solvent, dissolution and falling off of the polystyrene grain surface will be less likely to occur, and the dye will penetrate into the polystyrene. As a result, the same effect as the previous invention was obtained because the dyeing force, that is, the dyeing force, was generated. However, what is noteworthy is that in the previous invention, water was used as a solvent that did not dissolve the dye in a part of the dye solvent. Therefore, depending on the dye concentration, the dye may precipitate and precipitate, but since there are no dye-insoluble components in the dye solvent of the present invention, no matter what the dye concentration, the dye never precipitates. Sedimentation no longer occurs, and it has become possible to obtain better effects than the previous invention in terms of dyeing unevenness and density.

As a mixed solvent used as a dye solvent in the present invention, per 100 parts of alcohol, 10 to 100 parts of an organic solvent that is compatible with alcohol and dissolves polystyrene;
Preferably, a mixture of 20 to 60 parts of the solvent may be used.

If the organic solvent is less than the above ratio, the adhesion effect will be reduced and the desired coloration will not be achieved.On the other hand, if it is too much, the polystyrene particles may be welded together, the blowing agent may be released, the casing may be molded, etc. It becomes defective.

Next, the present invention will be further explained by examples, but the present invention is not limited thereto.

Example 1 Monoazo dye 5udan Yet low G G
N (5olvent.

A dye bath is prepared by dissolving 4 parts of Yel low 56.13 A SP g) in a mixture of 150 parts of methanol A and 50 parts of tetrahydrofuran. The obtained dye bath was heated to 35C
100. and stir for 15 minutes.

Thereafter, the expanded polystyrene particles were taken out from the dye bath and air-dried to obtain uniformly colored expanded polystyrene particles. The color density of these expanded polystyrene particles is extremely high, and the colored particles are sandwiched between 11 ml thick press plates.
It was foam-molded using a hot press adjusted to 50C, and the coloring density was judged to be extremely uniform, so the dyeability was judged to be good.

I sandwiched colored polystyrene foam 8 between white papers and rubbed it strongly with my hands to observe the transfer of the color to the white paper, and as there was no coloration at all, the dyeability was rated as good.

Example 2 Uniformly colored expanded polystyrene particles were obtained in the same manner as in Example 1 except that methanol was replaced with ethanol, and very good results were obtained in terms of dyeability and dyeability.

Example 3 Uniformly colored expanded polystyrene granules were obtained in the same manner as in Example 1 except that toluene was used instead of tetrahydrofuran, and very good results were obtained in terms of dyeability and dyeability.

Example 4 Anthraquinone dye MacroIex Blue F
Solve-nt Blve 78. Bayer
The same test as in Example 1 was carried out, except that a dye bath was prepared by dissolving 0.5 parts (manufactured by MITSUMI Co., Ltd.) in a mixture of 15 parts methanol and 50 parts tetrahydrofuran. Granules were obtained, and the dyeability and dyeability of the particles were very good.

Comparative Example 1 All procedures were carried out except for using water instead of methanol in Example 1. Colored expanded polystyrene particles were obtained in the same manner as in Example 1, but the dyeing concentration was extremely low compared to Example 1, and the degree of dyeing was approximately poor (
Comparative Example 2 The same procedure as in Example 4 was carried out except that water was used instead of methanol in the dye bath, but the foamed polystyrene particles could only be slightly colored, O Ratio Softness Example 3 The dyeing degree of only about ■ was obtained compared to Example 4. All the procedures were the same as Example 1 except that a solution of 200 parts of methanol was used instead of the tetrahydrofuran of Example 1. Expanded polystyrene particles were colored in the same manner, but the concentration was extremely low, and compared to Example 1, only about 1 degree of dyeing was obtained.

Comparative Example 4 Everything was carried out in the same manner as in Example 1 except that a solution of 200 parts of tetrahydrofuran was used instead of the methanol in Example 1, but each particle of expanded polystyrene was mutually fused and blocked. As a result, colored beads could not be obtained.

Claims (1)

[Claims] 1. When coloring expanded polystyrene grains, a liquid mixture consisting of 100 parts by weight of alcohol that does not dissolve polystyrene and 10 to 100 parts by weight of an organic solvent that is compatible with alcohol and dissolves polystyrene; A method for coloring expanded polystyrene granules, characterized by using a dye bath consisting of a dye soluble in a liquid.