JPS5923733B2 - Coloring method for expanded polystyrene particles - Google Patents

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.

In the production of molded articles made of expanded polystyrene, expanded polystyrene particles are usually used, and the expanded polystyrene particles contain a chemical blowing agent or a hydrocarbon gas as a blowing agent.

When producing a colored foamed molded product 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. However, this process 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. Next, there is a method of attaching pigments or dyes 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, resulting in brittleness. It can easily become a molded product.

The present inventors discovered that in order to achieve uniform coloring in a short time without using any coating adhesives such as pigments or dyes, and simply by immersing at room temperature, the inventors discovered that a mixture of water and an organic solvent was used. The inventor discovered that a method using a dye solution (hereinafter simply referred to as a dye bath) in which a dye is dissolved in a liquid solves the above-mentioned drawbacks and invented the invention (Japanese Patent No. 911153). After further investigation, we found that the dye that had been dissolved in the previous invention sometimes precipitated and settled, creating an uneven layer, resulting in slight areas with poor dyeability and difficulty in dyeing with a deep density. I found out that there are some things.

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. We have discovered that it is possible to form a homogeneous solution without any problems, and to make a considerably highly concentrated dye bath possible, and there is no welding of polystyrene grains together or a decrease in foaming properties, resulting in an effect exceeding that of the previous invention, and we have developed the present invention. I was able to complete it. That is, the gist of the present invention is that when coloring expanded polystyrene particles,
A method for coloring expanded polystyrene granules, characterized by using a mixed liquid comprising alcohol and an organic solvent that is compatible with the alcohol and dissolves polystyrene, and a dye bath comprising a dye soluble in the mixed liquid. Exists.

The alcohol used in the present invention usually has 1 to 1 carbon atoms.
6, preferably 2 to 5, more preferably aliphatic alcohols.

Specifically, methanol, ethanol, propanol,
Isopropanol, butanol, isobutanol, tertiary
grade butanol, amyl alcohol, methyl cellosolve,
Examples include ethyl cellosolve, butyl cellosolve, and the like. 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 toluene, xylene, benzene, gasoline, kerosene, ligroin, and tetralin. , alkylbenzene, turpentine oil, pine oil,
Liquid paraffin, etc., logenated hydrocarbons such as methylene chloride, chlorobenzene, chlorotoluene, bromobenzene, chlorinated liquid paraffin, etc., ketones,
For example, methyl isobutyl ketone, methyl-n-amyl ketone, methyl-n-hexyl ketone, ethyl-n-butyl ketone, cy-n-propyl ketone, acetophenone, etc., and ethers such as isopropyl ether, methyl phenyl ether, ethyl pen shell. In addition to ethers, furans, etc., esters such as isopropyl acetate, butyl acetate, butyl propionate, citric acid esters, ricinoleic esters, various phthalic esters, various oleic esters, various stearic esters, and various adipic acids. Examples include esters, various phosphoric acid esters, various abietic acid esters, various benzoic acid esters, and the like.

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 expanded polystyrene particles using these colorants, usually 0.1 to 10 parts (by weight, the same applies hereinafter) of the above dyes are dissolved in 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 dye bath is kept at 10 to 40°C, for example, the dye bath 10
Add 50 to 100 parts of expanded polystyrene grains to 0 parts.
After stirring for ~30 minutes, the expanded polystyrene granules are taken out from 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 poistyrene grains and a solvent that does dissolve the poistyrene grains in 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 the surface can be dyed uniformly and strongly, and in varying shades.

If expanded polystyrene grains are immersed in a dye solution containing only a solvent that easily dissolves polystyrene, the surface of the grains 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 expanded polystyrene grains is exposed, which not only makes foam molding difficult, but also causes problems such as welding of the polystyrene grains to each other and a portion of the polystyrene grains dissolving and flowing out. Its shortcomings make it impossible to put it into practical use. Therefore, if a solvent that is a mixture of 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 surface of polystyrene grains will be less likely to occur.
Since the ability of the dye to penetrate into polystyrene, that is, the ability to dye it, resulted in the same effect as the previous invention,
What should be noted is that in the previous invention, water was used as a solvent that does not dissolve the dye in the dye solvent, so depending on the dye concentration, the dye could precipitate and precipitate, but the dye of the present invention Since there are no dye-insoluble components in the solvent, no matter what the dye concentration, dye precipitation will never occur, and this invention has better effects than the previous invention in terms of dyeing unevenness and density. Now it is possible to obtain it.

As the mixed solvent used as a dye solvent in the present invention, alcohol is dissolved in 100 parts of alcohol, and
A solvent mixed with 10 to 100 parts, preferably 20 to 60 parts of an organic solvent that dissolves polystyrene may be used.

If the organic solvent is less than the above ratio, the dyeing effect will be reduced and it will be difficult to achieve the desired coloring, while if it is too much, the polystyrene particles will begin to weld together and the blowing agent will start to release, resulting in poor molding. It is.

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

Example 1 Monoazo dye SudanYellOwGG
4 parts of N (Solvent.YellOw56.BASF) were mixed with 150 parts of methanol and 50 parts of tetrahydrofuran.
A dyebath is prepared by dissolving it in a mixed solution.

The obtained dyebath was maintained at 35°C, and 100 parts of expanded polystyrene grains (Kaneru GM manufactured by Kanebuchi Kagaku Co., Ltd.) were added thereto.
After stirring for 5 minutes, 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 1 mm thick press plates and foam-molded using a heated press adjusted to 150°C.The color density is judged to be extremely uniform, so the dyeability is good. It was judged. In addition, colored expanded polystyrene particles were sandwiched between white sheets and rubbed strongly by hand to observe the transfer of color to the white paper. Since no color was formed at all, the dyeability was evaluated to be good. Example 2 Uniformly colored expanded polystyrene particles were obtained in the same manner as in Example 1, except that ethanol was used instead of methanol, and very good results were obtained in terms of dyeability and dyeability.

Example 3 Uniformly colored expanded polystyrene particles 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 MacrOlexBlueFR (
SolventBlve78. Bayer) 0,5
The same test as in Example 1 was carried out except that a dye bath was prepared by dissolving 150 parts of methanol and 50 parts of tetrahydrofuran in a mixture of 150 parts of methanol and 50 parts of tetrahydrofuran. Very good results were obtained with regard to stainability and dyeability.

Comparative Example 1 The same procedure as in Example 1 was carried out except that water was used instead of methanol in Example 1 to obtain colored expanded polystyrene particles. Comparative Example 2 The dyeing degree was about + (measured from the residual dye concentration in the dye bath) Comparative Example 2 All procedures were carried out in the same manner as in Example 4 except that water was used instead of methanol in Example 4, but foaming The polystyrene grains could only be slightly colored, and compared to Example 4, only about + degree of dyeing was obtained.

Comparative Example 3 Expanded polystyrene particles were colored in the same manner as in Example 1 except that a solution of 200 parts of methanol was used instead of the tetrahydrofuran in Example 1.
The concentration was extremely low, and compared to Example 1, only about + 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 used in Example 1, but each particle of expanded polystyrene was fused to each other. The beads became blocky and colored beads could not be obtained.

Claims (1)

[Claims] 1. For coloring expanded polystyrene grains, a mixed solution 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; and this mixed solution. A method for coloring expanded polystyrene granules, which is characterized by using a dye bath consisting of a dye soluble in .