JPH04189841A - Fcamed styrene resin particle and its production - Google Patents

Abstract

PURPOSE:To obtain the subject particle having excellent surface property, weldable under low steam pressure and giving a formed article such as fish box, agricultural crop container, cushioning material and heat-insulation material by impregnating a foaming agent and a polycyclic aromatic hydrocarbon as a foaming assistant into a styrene resin. CONSTITUTION:The objective resin particle is produced by impregnating a foaming agent (e.g. propane or monochloroethane) and a polycyclic aromatic hydrocarbon [preferably 1-phenyl-1-xylylethane, bis(alpha-methylbenzyl)xylene, 1- xylyl-1-(3-alpha-methylbenzylphenyl) ethane or 1-xylyl-1,3-diphenylbutane] as a foaming assistant into a styrene resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to novel and useful expandable styrenic resin particles and a method for producing the same.

More specifically, the present invention relates to a method for producing expandable resin particles having excellent surface properties and low steam pressure fusion properties by using a specific polycyclic aromatic hydrocarbon.

[Conventional technology]

1 to 20% by weight of a hydrocarbon blowing agent such as a hydrocarbon such as propane, butane, pentane, hexane, or cyclohexane, or a low boiling point halogenated hydrocarbon such as monochloroethane, dichloroethane, or dichlorodifluoromethane to the styrene resin. Expandable styrenic resin compositions are already known.

Expandable resin particles having such a composition are generally heated with water vapor or the like to form particulates having air bubbles inside.
These uniformly expanded particles are then heated further in a mold with small holes or slits, and these expanded particles fuse together to form various molded objects. give.

Therefore, in order to industrially obtain such porous molded products, so-called pre-expanded particles are prepared by directly exposing expandable styrenic resin particles that also contain these foaming aids to steam and foaming them. Next, the pre-expanded particles are placed in a mold to form the desired molded product.

As foaming aids, JP-A No. 50-53487 describes sepatic acid diesters such as dibutyl sepatate and dimethyl sepatate, phthalic acids such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, and dioctyl phthalate. Organic compounds such as diesters, and edible oils such as coconut oil, cornstarch oil, cottonseed oil, olive oil, palm oil, palm kernel oil, peanut oil, rapeseed oil, sesame oil, pork oil, beef oil, sheep oil, and fish oil are particularly important. 1977-121671, JP-A-52-121
672, JP-A-52-147669, JP-A-52-16
576 etc. are listed.

(Problems to be Solved by the Invention) However, since the above-mentioned organic compounds and edible oils do not have sufficient compatibility with styrene resins, foamable styrenic resins containing them as foaming aids The particles had poor low steam pressure fusion properties, and the surface properties of molded products obtained by molding them were also poor.

[Means for Solving Problem 1] Therefore, as a result of intensive studies to improve these drawbacks, the present inventors discovered expandable styrenic resin particles that have an overwhelmingly low steam molding temperature range, and completed the present invention. It's arrived.

That is, the present invention relates to expandable styrenic resin particles characterized by containing a polycyclic aromatic hydrocarbon, and a method for producing expandable styrenic resin particles in which the styrenic resin is impregnated with a blowing agent and a blowing aid. The present invention provides a method for producing expandable styrenic resin particles, characterized in that a polycyclic aromatic hydrocarbon is used as a foaming aid.

The expandable styrenic resin particles of the present invention may contain a blowing agent for foaming the styrenic resin particles and a polycyclic aromatic hydrocarbon, and the method for producing expandable styrenic resin particles is not particularly limited.

Any known and commonly used styrene resin particles can be used, including styrene homopolymers (polystyrene), alkylstyrene homopolymers such as methylstyrene, copolymers of styrene and alkylstyrene; Copolymers of styrene and acrylic esters or methacrylic esters; copolymers of styrene and acrylonitrile, and blends of the above styrene polymers and polyolefins; Particularly preferred are bead-like polymers obtained by a method.

As the blowing agent, any known and commonly used blowing agent can be used, including chain hydrocarbons such as propane, butane, pentane, hexane, heptane, and their isomers; halogenated blowing agents such as monochloroethane, dichloroethane, and dichlorofluoromethane. Examples include hydrocarbons. These blowing agents may be used alone or in combination. The content of the blowing agent contained in the styrene resin particles is not particularly limited, but is suitably within the range of 1 to 15 parts by weight based on 100 parts by weight of the styrene resin particles.

The polycyclic aromatic hydrocarbon of the present invention is not particularly limited as long as it is non-polymerizable. Examples of such polycyclic aromatic hydrocarbons include fused polycyclic aromatic hydrocarbons such as naphthalene, fluorene, anthracene, phenanthrene, acenaphthylene, and naphthacene, diphenylmethane,
Diaryl such as triphenyldimethane, 1-phenyl-1-xylylethane, bis(α-methylhensyl)xylene, ■-xylyl-1-(3-α-methylbenzylphenyl)ethane, 1-xylyl-1,3-diphenylbutane, etc. Examples include ethane and triallyldiethane, among which diallylethane and triallyldiethane are preferred. These polycyclic aromatic hydrocarbons may be used alone or in combination.

The amount of polycyclic aromatic hydrocarbon used is not particularly limited, but is usually 0.05 to 1.0 parts by weight, particularly 0.2 to 0.6 parts by weight, per 100 parts by weight of styrene resin particles. It is preferable that

The particle diameter of the expandable styrenic resin particles according to the present invention is not particularly limited, but is usually 0.5 to 1.5 mm.

Although the method for producing expandable styrenic resin particles according to the present invention is not particularly limited, for example, styrenic monomers are added in the presence of a suspension stabilizer, a surfactant, and a polymerization initiator as necessary. , a method of carrying out suspension polymerization in an aqueous medium. In this method, the blowing agent can be added at any stage of the suspension polymerization, or only styrene resin particles can be obtained by suspension polymerization, swollen in a solvent, and the blowing agent can be added. One method is to add it just before the completion of the process.

In addition, in the above production method, a polycyclic aromatic hydrocarbon as a foaming aid can be added at any stage of the suspension polymerization, for example, a method in which a system premixed with a styrene monomer is polymerized, Examples include a method in which the styrene monomer is added spot-wise or continuously during the polymerization of the styrenic monomer, and a method in which the styrenic monomer is added immediately before the completion of the polymerization reaction of the styrenic monomer.

The order of adding the blowing agent and the polycyclic aromatic hydrocarbon is also not particularly limited. Alternatively, a blowing agent may be added to a system in which a styrene monomer is polymerized in the presence of a polycyclic aromatic hydrocarbon, or a blowing agent and a polycyclic aromatic hydrocarbon may be added to a styrene monomer polymerization system. It may also be added to the system where the polymer is being polymerized.

The conditions for suspension polymerization are also not particularly limited, but usually 70 to 13
30 minutes to 24 hours at 0°C. Of course, since this is suspension polymerization, when polymerization is carried out at a temperature exceeding 100°C, it is preferable to carry out the polymerization in a pressure-resistant polymerization container such as an autoclave. When polymerization is carried out in a pressure-resistant container, an inert gas may be introduced as necessary to carry out the polymerization under pressurized conditions.

The expandable styrenic resin particles thus obtained contain a blowing agent and a polycyclic aromatic hydrocarbon impregnated therein.

When obtaining or molding the expandable styrenic resin particles according to the present invention, various additives can be used as appropriate.

When using propane, butane, penta/or cyclohexane, etc. alone or as a mixture as a blowing agent, aromatic hydrocarbons such as toluene, xylene, and ethylhenzene, esters such as ethyl acetate, butyl acetate, etc. A small amount of a known and commonly used solvent may be used in combination, and a nucleating agent such as ethylene bissteramide, clay, or talc may be added.

In addition, as coating agents, glycerin esters of higher fatty acids, higher fatty acid amides, metal soaps, talc,
Known and commonly used materials such as inorganic compound powder such as calcium carbonate, silicone oil, etc. can be used.

The method of molding the expandable styrenic resin particles according to the present invention is not particularly limited, but
After heating and foaming to an expansion ratio of 20 to 100 times by applying water vapor (pre-expanding step), the pre-expanded particles are exposed to the atmosphere to allow air to penetrate into the particles and remove moisture attached to the particles (aging step). A common method is then to fill the pre-expanded particles into a predetermined mold, heat them again with steam, and re-foam them to fuse and integrate the individual particles.

[Examples] Next, the present invention will be specifically explained with reference to Examples and Comparative Examples. In the following, all parts and percentages are based on weight unless otherwise specified.

Example 1 Tertiary phosphoric acid power/l/ as a suspension stabilizer in an autoclave
A mixture of 1 eM3, 0.05 part of sodium hydrodecyl henzene sulfonate, and 100 parts of pure water, 0.25 part of hensyl peroxide as a catalyst, and tert
- 0.05 part of butyl perhenzoate to 100 parts of styrene
The solution dissolved in the solution and the bicyclic aromatic hydrocarbon (bis
methylbenzyl]xylene, 1-xylyl-1-(3-
α-Methylhensylphenyl)ethane, 1-xylyl-
0.5 part of 1,3 diphenylbutane (a mixture having a composition ratio of 20:5 to 5) was charged, polymerization was carried out at 85°C, and when the polymerization rate reached 90%, tricalcium phosphate 2
After adding 1.5 parts of cyclohexane to 8.5 parts of butane as a blowing agent, the temperature was raised to 115 parts.
After completing the polymerization at ℃ and then cooling, the produced beads were taken out, dehydrated, dried, and classified to a particle size of 0.9±0.
Polystyrene beads of 1 mm were obtained.

After coating the beads to prevent agglomeration during pre-foaming, the beads were pre-foamed to a bulk specific gravity of 65 times, and the pre-foamed particles were
After aging for a period of time, it was filled into a mold and molded using a steam molding machine under certain conditions. The results are shown in Table-1.

(◎OΔ× in the table indicates the surface condition. ◎~Excellent, ○~Good, Δ~Slightly poor, Percentage of particles torn inside the foamed particles relative to the total particles when the molded product is torn
It is expressed as Example 2 Polystyrene beads were obtained by carrying out the same operation as in Example 1, except that the bicyclic aromatic hydrocarbon was replaced with the same amount of 1-xylyl-1,3-diphenylbutane, followed by pre-foaming and aging. I did the molding. The obtained molded article was evaluated in the same manner as in Example 1. Two results are shown in the table.

Comparative Example 1 Polystyrene beads were obtained by performing the same operation as in Example 1 except that the same amount of soybean oil was substituted for the bicyclic aromatic hydrocarbon,
After preliminary foaming and aging, molding was performed. The obtained molded article was evaluated in the same manner as in Example 1. The results are shown in Table-1.

Comparative Example 2 Polystyrene beads were obtained in the same manner as in Example 1, except that no two-ring aromatic hydrocarbon was used, and the beads were pre-foamed, aged, and then molded. The obtained molded article was evaluated in the same manner as in Example 1. The results are shown in Table-1.

As can be seen from Table 1, it is clear that the expandable styrenic resin of the present invention allows molded products with approximately the same fusion rate as conventional molded products even at low steam pressure, and also has excellent surface properties.

[Effects of the Invention] Since the expandable styrenic resin particles of the present invention contain polycyclic aromatic hydrocarbons, during molding, cycle-up is possible due to excellent low steam pressure fusion properties,
Moreover, it has the particularly remarkable effect that a molded article with excellent surface properties can be obtained.

Molded products obtained by molding the expandable styrene resin particles of the present invention can be used as containers for fish boxes and agricultural products, as cushioning materials for storing and transporting electrical parts and appliances, or for construction purposes. Can be used as insulation material.

Agent: Patent attorney Katsutoshi Takahashi

Claims (1)

[Scope of Claims] 1. Expandable styrenic resin particles characterized by containing a polycyclic aromatic hydrocarbon. 2. The expandable styrenic resin particles according to claim 1, wherein the polycyclic aromatic hydrocarbon has two or three benzene rings. 3. The polycyclic aromatic hydrocarbon is 1-phenyl-1-xylylethane, bis(α-methylbenzyl)xylene, 1-
The expandable styrenic resin particles according to claim 1, which are at least one hydrocarbon selected from the group consisting of xylyl-1-(3-α-methylbenzylphenyl)ethane and 1-xylyl-1,3-diphenylbutane. . 4. A method for producing expandable styrenic resin particles in which a styrene resin is impregnated with a blowing agent and a foaming aid, characterized in that a polycyclic aromatic hydrocarbon is used as the foaming aid. Method of manufacturing particles.