JPH0791409B2 - Expandable styrene resin particle composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a foamable styrene resin particle composition, and more specifically, a molded article obtained by foam molding the particles is used as a container. And a suitable expandable styrene resin particle composition.

(Prior Art) The expandable styrenic resin particles are heated by steam or the like to be primary foamed, then filled in a mold having small holes, heated, secondary foamed and molded. Molded products are used in many fields as packing materials, heat insulating materials, containers, etc., because they are economical, heat insulating, lightweight, hygienic and the like.

Expandable styrenic resin particles are generally aliphatic hydrocarbons that are gaseous or liquid at room temperature, such as propane, butane,
It is manufactured by a method in which pentane, hexane and the like are dispersed together with polystyrene beads in an aqueous medium and heated.
The expandable styrenic resin particles obtained in this way are molded through the above-mentioned process, but the obtained molded product is made by stacking the expandable styrenic resin particles in the shape of a stone wall and melting them by foaming pressure and heat. Since they are deposited, the particles are not integrated so that when used as a container, their contents tend to penetrate the outer wall of the container. In order to prevent permeation, there is a method in which the fusibility of the particles is strengthened, the permeable voids are reduced, or the surface properties of the particles are made incompatible with the contents.

Generally, the former method is to increase the heating during molding. In order to obtain a molded product with fewer defects, it is necessary to set the molding temperature to a low temperature and to heat it for a long time. .

As the latter method, generally used metal soap is used in a larger amount than usual in order to prevent agglomeration of the particles in the primary foaming, but fusion of particles is inhibited in molding. Therefore, the molding time becomes long as in the above-mentioned method, and in any case, the molding cycle is long, and it is hard to say that this method is industrially useful.

Therefore, expandable styrenic resin particles have been proposed in the past with a shorter molding time and less penetration of the contents. For example, in JP-B-56-34172, the surface of expandable styrene-based resin particles is coated with sucrose ester, and in JP-B-56-51178, the surface of expandable styrene-based resin particles is coated with polyether or polyol and polyphosphate. In JP-A-59-24731, coating of the surface of expandable styrenic resin particles with fatty acid ester of polyalkylene glycol, JP-A-59-41
Japanese Patent No. 339 proposes coating the surface of expandable styrene resin particles with a perfluoroalkyl group-containing phosphate ester.

(Problems to be Solved by the Invention) Of the above-mentioned publications, except for JP-A-59-41339, it is intended to prevent a molded container from penetrating the intended contents to be stored. Yes, and different things were stored and showed different results. On the other hand,
Japanese Patent No. 59-41339 is characterized in that a perfluoroalkyl group-containing phosphate ester is coated on the surface of a foamable styrenic resin in an amount of 0.01 to 0.2% by weight, which is generally used as a water and oil repellent agent for fibers and paper. It has been used and is effective in repelling and preventing penetration of any of the items of the invention.

However, the perfluoroalkyl group-containing phosphate ester also has the function of inhibiting the heat fusion of the expanded particles,
As a result, the time required for heating at the time of molding became long and the initial purpose could not be achieved.

The present invention provides an expandable styrenic resin particle composition,
It is an object of the present invention to provide an expandable styrene resin particle composition in which the content stored does not penetrate into the outer wall of the container when it is used as a container and can be molded in a short molding time.

(Means for Solving the Problems) The present invention provides a compound of the general formula (I); (However, l is an integer of 4 to 10, m is 1 or 2, n is an integer of 2 to 10, R ₁ is H, an alkyl group having 1 to 18 carbons, or 1 carbon
To 18 hydroxyl group-containing alkyl groups) to a foamable styrenic resin particle composition having a coating layer as an essential component.

As the expandable styrenic resin particles in the present invention, conventionally known ones can be used, and homopolymers of styrene or styrene and acrylonitrile, methyl methacrylate, methacrylic acid esters such as butyl methacrylate, methyl acrylate, ethyl acrylate, Acrylic esters such as butyl acrylate, styrene derivatives such as α-methylstyrene, chlorostyrene, vinyltoluene, etc. 1
As a base resin of one kind or a copolymer of two or more kinds, and an aliphatic hydrocarbon such as propane, isobutane, n-butane, isopentane, and n-pentane, or Freon 11, Freon 1
It is preferably such that a foaming agent which is liquid or gaseous at room temperature, such as a CFC compound such as 2, is impregnated at 1 to 10% by weight. These expandable styrene resin particles can be produced by a known method.

The compound represented by the general formula (I) used for coating the expandable styrenic resin particles is a perfluoroalkylsulfonamide ammonium phosphate, which is a known compound.

Specific examples of the compound represented by formula (I) are shown below.

The amount of the compound represented by the general formula (I) used is preferably 0.0001 to 0.05% by weight, more preferably 0.001 to 0.02% by weight, based on the expandable styrenic resin particles. If the amount of this compound used is too small, it becomes difficult to obtain a sufficient water / oil repellency effect, and if it is too large, not only does the effect not improve so much, but also heat fusion between resin particles is hindered in the molding process. Resulting in.

In coating the expandable styrenic resin particles, in addition to the compound represented by the general formula (I), conventionally known coating agent components can be used in combination. Examples thereof include metal soaps such as zinc stearate and calcium stearate used for preventing agglomeration in temporary foaming, and fatty acid amides such as ethylene bisamide and stearic acid amide. These agglomeration inhibitors are preferably used in an amount of 0.05 to 0.5% by weight based on the expandable styrenic resin particles. In addition, glycerin, sorbit, polyhydric alcohols such as polyethylene glycol and polypropylene glycol, which are used as antistatic agents for expanded resin particles, sorbitan esters, and nonionic surfactants such as higher aliphatic ethylene oxide adducts can be used in combination. It is possible. These antistatic agents are added to expandable styrenic resin particles at 0.
It is preferably used from 005 to 0.2% by weight.

In the present invention, the formation of the coating layer on the surface of the expandable styrenic resin particles can be performed by a conventionally known means. For example, it can be carried out by mixing the expandable styrenic resin particles and the above-mentioned respective coating agent components in a mixer such as a ribbon blender, a V blender, a Hensiel mixer, and a Redige mixer.

By using the expandable styrenic resin particle composition thus obtained, the particles are well fused even with a short molding heating.
In addition, a molded product having water-repellent and oil-repellent properties at its particle interface can be obtained. For example, the contact angle of soybean oil in the conventional molded product is around 40 °, whereas it becomes difficult to wet at 50-60 °.

Therefore, the composition of the present invention is a container which can prevent the penetration of the oily or fatty food such as donut, hamburger, fried chicken, instant noodles, curry roux, lard and mayonnaise through the wall to the outside of the container. It becomes the material for making.

Examples Examples 1-2 5.5% by weight of pentane (i-pentane / n-as a blowing agent)
1000 g of expandable polystyrene particles (5SG manufactured by Hitachi Chemical Co., Ltd.) containing 0.35 to 0.59 mm in diameter containing pentane = 1/9) were placed in a Hensiel mixer, and ammonium bis (N-ethyl-2-perfluoro) was added thereto. Octylsulfonamidoethyl) phosphate Table 1 shows the amount (in terms of solid content) of zinc stearate 1.
5 g and 0.5 g of glycerin were sequentially added and mixed for coating to obtain a foamable polystyrene resin particle composition. This was heated in a batch type primary foaming device using a mixture of hot air and steam as a heating medium, and foamed to a bulk density of 0.1 g / ml to obtain primary expanded particles. After aging this for 16 hours at room temperature and normal pressure, it was filled in a mold for obtaining a cup-shaped molded product with an internal volume of 500cc and a wall thickness of 2.0mm, heated for the time shown in Table 1, and then cooled for 4 hours,
A foam polystyrene cup was obtained.

350 cc of salad oil was put in the obtained cup and a permeability test was conducted, and the time until oozing is shown in Table 1. Further, the obtained cup was broken and the ratio of the particles that did not separate at the interface between the particles and cracked themselves was examined, and the fusion degree is shown in Table 1.

Comparative Examples 1-2 A foamed styrene cup was obtained and tested in the same manner as in Example 1 except that ammonium bis (N-ethyl-2-perfluorooctylsulfonamidoethyl) phosphate was not used. The results are shown in Table 1.

Comparative Examples 3 to 4 In Example 2, ammonium bis (N ethyl-2-
Instead of using perfluorooctylsulfonamidoethyl) phosphate, ammonium perfluoroalkyl phosphate (Surflon S-112, manufactured by Asahi Glass Co., Ltd.) was used, and a styrofoam cup was obtained and tested in the same manner. The results are shown in Table 1.

(Effects of the Invention) The expandable styrenic resin particle composition of the present invention can be molded in a short molding time, and when formed as a container, the stored contents are less likely to penetrate the wall of the container.

Claims (2)

[Claims] 1. The surface of the expandable styrenic resin particles has the general formula (I); (However, l is an integer of 4 to 10, m is 1 or 2, n is an integer of 2 to 10, R ₁ is H, an alkyl group having 1 to 18 carbons, or 1 carbon
To 18 is a hydroxyl group-containing alkyl group), and an expandable styrene resin particle composition having a coating layer containing a compound represented by the formula (1) as an essential component. 2. The amount of the compound represented by the general formula (I) is
0.0001 to 0.05% by weight based on expandable styrene resin particles
The expandable styrene resin particle composition according to claim 1.