JPH0733448B2 - 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 and temporarily 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 resulting molded product is made by stacking the expandable styrene resin particles in a stone wall shape and fusing by foaming pressure and heat. Therefore, the particles are not integrated with each other, and as a result, when used as a container, the contents thereof easily penetrate into 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. , JP-A-59-24731
JP-A-59-
Japanese Patent No. 41339 proposes coating the surface of expandable styrene resin particles with a perfluoroalkyl group-containing phosphate ester.

(Problems to be Solved by the Invention) In the above-mentioned publications, except for JP-A-59-41339, it is possible to prevent a molded container from penetrating the contents to be stored, which is intended for the use of the container. It was prevented, and showed different results in different things contained.
On the other hand, JP-A-59-41339 discloses that a perfluoroalkyl group-containing phosphoric acid ester is added to the surface of a foamable styrene resin in an amount of 0.
It is characterized by being coated with 01 to 0.2% by weight, which is already commonly used as a water and oil repellent for fibers and papers, and is effective in repelling any of the contents of the present invention and preventing penetration. is there. However, the perfluoroalkyl group-containing phosphate ester also has a function of inhibiting the heat-sealing of the expanded particles, and as a result, the heating time required during molding becomes long and the initial purpose cannot be achieved. It was

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 Problem) The present invention is directed to the formation of expandable styrene-based resin particles in which the surface of the expandable styrene-based resin particles is 0.0001% by weight or more and less than 0.005% by weight of ammonium perfluoroalkyl phosphate and expandable styrene. 0.0001 to 0.01% by weight based on the resin particles
Of the expandable styrene-based resin particle composition, which is coated with a layer containing the cationic polyacrylamide resin 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 ammonium perfluoroalkyl phosphate used in the present invention has a general formula: (CmF ₂ m _{+ 1} · CnH ₂ nO) _Y PO (ONH ₄ ) _(3-Y) [wherein, m is 4 to 10; An integer, n is an integer of 1 to 11, m + n is 8 or more, and Y is 1 or 2.], and examples thereof include the following.

_{[F (CF 2) 6 CH 2} CH 2 O ] ₂ PO (ONH _{4) [F (CF 2) 4 (CH} 2) 4 O ] ₂ PO (ONH _{4) [F (CF 2) 3 (CH} 2) ₁₁ O] ₂ PO (ONH ₄ ) [F (CF ₂ ) ₈ CH ₂ CH ₂ O] PO (ONH ₄ ) ₂ [F (CF ₂ ) ₇ CH ₂ O] ₂ PO [ONH ₂ (CH ₂ CH ₂ OH ) ₂ ] [F (CF ₂ ) ₇ CH ₂ CH ₂ O] ₂ PO [ONH ₂ (CH ₂ CH ₂ OH) ₂ ] [F (CF ₂ ) ₁₁ CH ₂ CH ₂ O] PO [ONH ₂ (CH ₂ CH ₂ OH) ₂ ] ₂ These substances can be used alone or in combination.

As ammonium perfluoroalkyl phosphate, Surflon S-112, AG-530, AG-730, AG-710, AG-740, AG
-550 (all are trade names, manufactured by Asahi Glass Co., Ltd.), Zonir R
P (trade name, manufactured by Deyupon), Sumiretsu Resin FP-11
0, FP-15, FP-1910, FP-130 (all are trade names, manufactured by Sumitomo Chemical Co., Ltd.) and the like are commercially available.

The cationic polyacrylamide resin in the present invention is a resin obtained by cationically modifying a copolymer obtained by copolymerizing acrylamide monomer and one or more monomers copolymerizable with the acrylamide monomer.

Examples of the monomer copolymerizable with the acrylamide monomer include N-methylol acrylamide, methacrylamide, diacetone acrylamide, methyl acrylate, ethyl acrylate, butyl acrylate, propyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate and methacrylic acid. Examples include ethyl, butyl methacrylate, hydroxyethyl acrylate, and hydroxyethyl methacrylate. Other copolymerizable components may include vinyl acetate, styrene, α-methylstyrene, vinylidene chloride, maleic anhydride and the like.

As a cationization modification method of the polyacrylic acid amide resin, there are known methods such as Mannich reaction and Hoffmann decomposition. Alternatively, a cation-modified monomer may be copolymerized in advance.

This cationic polyacrylamide resin acts on the above-mentioned ammonium perfluoroalkylphosphate to increase the water / oil repellency of ammonium perfluoroalkylphosphate. Commercially available cationic polyacrylamide resin manufactured by Meisei Chemical Co., Ltd.
AG-Fix S-45, AG-Fix M-15, Meirup 75
There is 1 mag.

The amount of ammonium perfluoroalkyl phosphate used in the present invention is 0.0001 with respect to the expandable styrene resin particles.
% Or more and less than 0.005% by weight, preferably 0.001
~ 0.004% by weight. If it is less than 0.0001% by weight, sufficient water repellency and oil repellency cannot be obtained, and if it is more than 0.005% by weight, heat fusion of the expandable styrenic resin particles during molding is hindered.

The amount of cationic polyacrylamide resin used is
0.0001 to 0.01% by weight based on expandable styrene resin particles
Is. When it is less than 0.0001% by weight, the function of increasing the water / oil repellency of ammonium perfluoroalkylphosphate is not sufficient, and when it exceeds 0.01% by weight, the heat fusion of the expandable styrene resin particles in molding is inhibited. .

The ratio of ammonium perfluoroalkylphosphate to cationic polyacrylamide resin is 3: 1 to 1: 2 for ammonium perfluoroalkylphosphate: cationic polyacrylamide resin, which means that sufficient oil / water repellency is obtained. It is preferable to have it.

In the present invention, conventionally known coating agent components can be used in combination with the above-mentioned two components. For example, zinc stearate used to prevent agglomeration in primary foaming,
Metal soap such as calcium stearate, 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, it is also possible to use nonionic surfactants such as glycerin, sorbit, polyhydric alcohols such as polyethylene glycol and polypropylene glycol, sorbitan esters, and higher aliphatic ethylene oxide adducts that are used as antistatic agents for primary expanded resin particles. It is possible. These antistatic agents are preferably used in an amount of 0.005 to 0.2% by weight based on the expandable styrenic resin particles.

In the present invention, the coating layer on the surface of the expandable styrene resin particles can be formed 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, in the case of a conventional molded product, the contact angle with soybean oil is around 40 °, whereas it becomes difficult to get wet at 50-60 °. Therefore, the composition of the present invention comprises a donut, a hamburger,
Even if you directly package oily or fatty foods such as fried chicken, instant noodles, curry roux, lard, mayonnaise,
It is a material for making a container that can prevent penetration of the container through the wall.

(Examples) The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto.

Examples 1-2 and Comparative Examples 1-4 Diameter containing 5.3% by weight of n-pentane as blowing agent
The cationic polyacrylamide resin shown in Table 1 was added to 1000 g of expandable polystyrene resin particles (5SG, manufactured by Hitachi Chemical Co., Ltd.) having a size of 0.35 to 0.59 mm, and the mixture was mixed with Henschel mixer. Ammonium fluoroalkyl phosphate, zinc stearate 1.5g and glycerin 0.5g
Were sequentially added and mixed, and the expandable polystyrene resin particles were coated and coated to obtain an expandable 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 was expanded to 10 times (volume) to obtain primary expanded particles.

After aging the primary expanded particles for 16 hours in air, the internal volume was 500c
It was filled in a mold for obtaining a cup-shaped molded product having a thickness of 2.0 mm and heated for the time shown in Table 1 to obtain a molded product.

350 cc of salad oil was put into the obtained cup, a permeability test was conducted, and the time until exudation is shown in Table 1.

Further, the obtained cups were 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.

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

Claims (2)

[Claims] 1. The surface of the expandable styrene resin particles is 0.0001% by weight or more and 0.005% by weight or more with respect to the expandable styrene resin particles.
Expandable styrenic resin particle composition coated with a layer containing 0.0001 to 0.01% by weight of a cationic polyacrylamide resin as an essential component with respect to less than 1% by weight of ammonium perfluoroalkyl phosphate and expandable styrene resin particles. . 2. Ammonium perfluoroalkyl phosphate has the general formula: (CmF ₂ m _{+ 1} · CnH ₂ nO) _Y PO (ONH ₄ ) _(3-Y) [wherein m is an integer of 4 to 10] , n is an integer of 1 to 11, m + n is 8 or more, and Y is 1 or 2.], The expandable styrenic resin particle composition according to claim 1.