JPH08208877A - Expandable styrene resin particle - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a novel expandable styrenic resin particle suitable for recycling without causing a bad odor or an offensive odor when the foamed molded product is recycled by a method such as melting and re-pelletizing. With the goal. A foamable styrene-based resin particle comprising a foamable styrene-based resin particle composed of a styrene-based resin and an easily volatile foaming agent and containing at least a terpene-based hydrocarbon as a foaming aid. be able to.

Description

Detailed Description of the Invention

The present invention relates to a novel expandable styrenic resin suitable for recycling, and particularly to a bad odor when a foamed molded product formed by using the expandable styrene resin particles is recycled by a method such as melting and re-pelletizing. The present invention relates to a novel expandable styrenic resin particle suitable for recycling, which does not cause a nasty smell.

[0002]

2. Description of the Related Art Expandable styrene resin particles (foam beads) obtained by impregnating a styrene resin with a foaming agent made of an easily volatile solvent are often used to heat foam to obtain a foam molded article. It is known that the foamed molded product obtained in this way has a cushioning property and a heat insulating property. Therefore, by utilizing this property, the foamable styrene-based molded product is widely used as a cushioning material, a heat insulating material, or various containers. Has been done.

However, in the production of expandable styrene resin particles, toluene, cyclohexane, which has an affinity with the styrene resin, together with the styrene resin and the foaming agent,
It is well known that the addition of an organic solvent such as ethylbenzene improves the foaming agent holding power and plasticizing effect of the expandable styrene resin particles to increase the foaming power (Japanese Patent Office, well-known conventional technique). See pages 23 to 24 (Foam molding), August 3, 1982, issued by the Japan Patent Office. Recently, it has been practiced to recycle foamed molded articles to form expandable particles again. But,
When a foamed molded product of styrene resin is melted, re-pelletized and recycled, there is a problem in that odors and bad odors are generated based on the solvent used as the foaming auxiliary, and thus the workability of recycling is reduced. It was

[0004]

Therefore, the inventor of the present invention
Upon recycling, as a result of various studies on foaming aids that do not generate such odors or odors, terpene hydrocarbons did not reduce the plasticity of the expandable styrene resin particles and the holding power of the foaming agent, and In addition to showing efficacy as an agent, it was found that no odor and no bad odor are generated when recycling a molded article molded with the expanded particles, and the present invention has been completed. An object of the present invention is to provide expanded styrenic resin particles that do not generate an offensive odor.

[0005]

That is, according to the present invention, expandable styrene resin particles composed of a styrene resin and an easily volatile foaming agent contain at least a terpene hydrocarbon as a foaming aid. The feature is expandable styrenic resin particles, by using a terpene hydrocarbon as a foaming aid, especially the amount of various organic solvents conventionally used as a foaming aid can be used. It is possible to obtain a foamed styrenic resin foamed product by a method similar to the conventional one, by reducing or without using the organic solvent at all. This is solved by providing expandable styrenic resin particles.

The present invention will be described in detail below. The styrene-based resin used in the present invention is a styrene-based monomer alone or a copolymer with another co-monomer.
Examples of the styrene-based monomer include styrene, paramethylstyrene, vinyltoluene, tertiary-butylstyrene and the like. Examples of copolymerizable comonomers include acrylonitrile, methylmethacrylate, maleic anhydride, acrylic acid, methacrylic acid and N-phenylmaleimide. These styrene resins are polymerized by a known method. Among them, styrene monomer
In the case of the homopolymer and the styrene-acrylonitrile copolymer resin of (1), it is easy to obtain a high-magnification foam by heating and foaming once, and therefore it can be suitably used. And, in the present invention, these homopolymers or copolymers are used in the form of particles, but the styrene resin particles are not particularly limited, and the shape thereof is a pallet shape (spherical shape), an elliptic shape. , And pellet-shaped (cylindrical) particles may be used.

The foaming agent used in the present invention includes:
Easily volatile blowing agents such as aliphatic hydrocarbons and halogenated hydrocarbons can be used alone or in combination of two or more. Specific examples of the aliphatic hydrocarbon include, for example, propane and n-
Examples include butane, isobutane, n-pentane, isopentane, cyclopentane and the like. Further, as specific examples of the halogenated hydrocarbon, for example, trichloromonofluoromethane, cyclodifluoromethane, monochlorotrifluoromethane, dichloromonofluoromethane, monochlorodifluoromethane, trichlorotrifluoroethane, dichlorotetrafluoroethane, dichlorotrifluoroethane. , Monochloropentanefluoroethane, monochlorotetrafluoroethane, monochlorotrifluoroethane, monochlorodifluoroethane, tetrafluoroethane, difluoroethane and the like.

The means for incorporating the foaming agent into the styrene resin particles is not particularly limited, and a conventionally used method may be used. For example, when a styrene-based resin is produced by an aqueous suspension polymerization method, a method in which a foaming agent is added during the polymerization to perform polymerization and impregnation at the same time, or styrene-based resin particles are brought into an aqueous suspension state, and a foaming agent is added thereto Addition, impregnation method, or extruded in an unfoamed state after impregnating a styrenic resin with a foaming agent in an extruder,
There is a method of pelletizing this. Styrene resin particles impregnated with a foaming agent obtained by these methods,
The foamable styrenic resin particles can be obtained after performing such means as dehydration, drying and aging.

In the expandable styrenic resin particles of the present invention, the amount of the foaming agent is 1 part with respect to 100 parts by weight of the styrene resin.
The amount of the foaming agent is preferably 2.0 to 6.0 parts by weight with respect to 100 parts by weight of the styrene resin. When the amount of the foaming agent is more than 8 parts by weight, it is difficult to uniformly disperse the foaming agent in the resin particles, which tends to result in a non-uniform foam, which is not preferable, and when the amount of the foaming agent is less than 1 part by weight. ,
It is not preferable because it is difficult to foam sufficiently high.

In the present invention, the expandable styrene resin particles impregnated with the above-mentioned foaming agent contain terpene hydrocarbon as a foaming aid. Terpene hydrocarbons are contained in many plant oils (orange peel oil, lemon oil, bergamot oil, saltwater oil, peppermint oil, etc.), and among these terpene compounds, especially monoterpenes have a lemon-like aroma. Therefore, it is most preferable for use. Even when a terpell hydrocarbon having such an aroma is used together with an organic solvent which is a conventional foaming aid, the offensive odor can be significantly suppressed.

Specific examples of monoterpenes that can be used include limonene, terpinene, myrcene, karen ocimene,
Examples include camphene, terpinole, tricyclen, fenchen, ferrandrene, sylvestrene, sapinen and the like. The amount of the terpene hydrocarbon that can be used is 0.1 to 3.0 parts by weight, preferably 0.5 to 100 parts by weight of the styrene resin.
˜2.0 parts by weight is preferable. Further, in the present invention, a conventional flame retardant, an antistatic agent or the like may be added to the expandable styrenic resin particles as needed. The means for adding the terpene hydrocarbon is not particularly limited, and may be added before adding the foaming agent, simultaneously with the foaming agent, or added to the expandable styrene resin impregnated with the foaming agent.

[0012]

EXAMPLES AND COMPARATIVE EXAMPLES Next, the method of the present invention will be described in more detail with reference to Examples. Example 1 Polystyrene resin particles (KS-141C polymer manufactured by Sekisui Plastics Co., Ltd.) were placed on an autoclave equipped with a rotary stirrer.
100 parts of water was added, and 0.3 parts of magnesium pyrophosphate and sodium dodecylbenzene sulfonate were previously added to 100 parts of water.
A solution in which 0.04 parts and 1.9 parts of limonene were sufficiently emulsified and dispersed was added to the autoclave, the autoclave was closed, and 7 parts of butane as a foaming agent was press-fitted, and the agitator was used. While rotating, it was left at 90 ° C. for 4 hours. After that, the polystyrene resin particles (expandable polystyrene resin particles) were cooled to room temperature, taken out of the system, washed with water and dried, and then stored in a closed container for 2 days. The expandable polystyrene resin particles obtained are heated with steam to pre-expand to a bulk factor of 60, left for one day and then filled in a closed mold, and heated with steam to give 400 m / m × 300 m / m × A foamed molded article having a beautiful appearance of 100 m / m and good fusion bonding was obtained. This foamed molded product was crushed into pieces of approximately 10 m / mφ, charged into a 500 cc Erlenmeyer flask, and then the flask was heated to 125 ° C. with a mantle heater to melt the foamed product therein,
When the odor generated from the flask was confirmed, there was no bad odor such as toluene odor, and only a scent similar to orange was felt.

Example 2 Polystyrene resin particles (KS-141C polymer manufactured by Sekisui Plastics Co., Ltd.) were added to an autoclave equipped with a rotary stirrer.
100 parts of water was added, and 0.3 parts of magnesium pyrophosphate and sodium dodecylbenzene sulfonate were previously added to 100 parts of water.
A solution in which 0.04 parts, 1.6 parts of toluene and 0.3 parts of limonene were sufficiently emulsified and dispersed was added to the autoclave, and then the autoclave was closed to form butane 7 as a foaming agent.
The parts were press-fitted, and the mixture was left at 90 ° C. for 4 hours while rotating the stirrer. After that, the polystyrene resin particles (expandable polystyrene resin particles) were cooled to room temperature, taken out of the system, washed with water and dried, and then stored in a closed container for 2 days. The expandable polystyrene resin particles thus obtained are heated with steam to pre-expand to a bulk factor of 60, left standing for one day and then filled in a closed mold, and heated with steam to 400 m / m × 300 m / m.
A foamed molded product having a beautiful appearance of × 100 m / m and good fusion bonding was obtained. This foamed molded product was crushed into pieces of approximately 10 m / mφ, charged into a 500 cc Erlenmeyer flask, and then the flask was heated to 125 ° C. with a mantle heater to melt the foamed product therein, When the generated odor was confirmed, no odor such as toluene odor was found.

[0014]

As described above, in the present invention, by adding terpene hydrocarbon as a foaming aid,
Even when the molded product molded from the expanded styrene resin particles was recycled, melted, and re-pelletized, the workability of recycling could be improved without generating an odor or a bad odor.

Claims (1)

[Claims] 1. A foamable styrene-based resin particle comprising a foamable styrene-based resin particle comprising a styrene-based resin and an easily volatile foaming agent, and containing at least a terpene-based hydrocarbon as a foaming aid.