JP5496636B2 - Agricultural containers - Google Patents

Description

  This invention has no stickiness of particles, facilitates particle transfer, and does not peel off chemicals coated on piping, as expandable styrene resin particles, pre-expanded particles using the same, and foamed molded articles thereof It relates to containers for agricultural products.

  Conventionally, expandable styrene resin particles obtained by impregnating a styrene resin particle with a physical foaming agent are pre-foamed by a pre-foaming machine to produce pre-foamed particles. After filling in the mold, it was heated and subjected to secondary foaming and fused together to produce a foam molded product having a desired shape.

  A characteristic required for such expandable styrene resin particles is that when the expandable styrene resin particles are pre-expanded by heating with steam or the like, a plurality of expandable styrene resin particles are pre-expanded. In other words, there is no so-called blocking, and the pre-expanded particles are sufficiently fused together when the pre-expanded particles are secondarily expanded.

  When the foaming styrenic resin particles are pre-foamed, if the above-mentioned blocking of the pre-foamed particles occurs, the pre-foamed particles are filled in the feeder when filling the pre-foamed particles into the mold of the foam molding machine. As a result, defective filling of the pre-expanded particles into the mold of the foam molding machine occurs, and a satisfactory foam molded product cannot be obtained. Further, when the pre-foamed particles are subjected to secondary foaming, if the pre-foamed particles are not sufficiently heat-sealed and integrated, there arises a problem that the mechanical strength of the resulting foam-molded product becomes insufficient.

  Therefore, in order to prevent blocking of the expandable styrene resin particles during the pre-expansion of the expandable styrene resin particles, a metal salt of a fatty acid such as zinc stearate or magnesium stearate is formed on the surface of the expandable styrene resin particles. An anti-blocking agent such as is attached.

  Furthermore, the surface of the expandable styrene resin particles is coated with fatty acid triglyceride for the purpose of improving the heat-fusibility between the pre-expanded particles during the secondary expansion of the pre-expanded particles, or the expandable styrene-based In order to prevent dust and the like from adhering to the surface of the resin particles due to static electricity, the surface of the expandable styrene resin particles is coated with a fatty acid monoglyceride.

Specifically, Patent Document 1 proposes expandable styrene polymer particles obtained by applying a predetermined glycerin fatty acid ester and zinc stearate and / or an inorganic substance on the surface of expandable styrene polymer particles. In addition, it is described that the coating agent applied to the surface of the expandable styrene polymer particles does not peel off.
Patent Document 2 proposes expandable styrene resin particles in which the surface of expandable styrene resin particles is coated with fatty acid glycerin ester particles having a predetermined diameter and a fatty acid metal salt.

  On the other hand, in the process of producing a foam molded product by foaming expandable styrene resin particles, the expandable styrene resin particles are disposed in an expandable particle distribution pipe (pipe) having one end connected to a preliminary foaming machine. The pre-foamed particles obtained by being pre-foamed by the pre-foaming machine as well as being supplied into the pre-foaming machine through so-called pneumatic transport through the foamable particle flow pipe sucked toward the pre-foaming machine are silo at one end. Alternatively, the pre-expanded particle distribution pipe connected to the foam molding machine is supplied to the silo or the foam molding machine through the pre-expanded particle distribution pipe by sucking the pre-expanded particle distribution pipe toward the silo or the foam molding machine. It is arranged in a partially or entirely curved state depending on the arrangement of the machine and the foam molding machine.

JP-A-4-320434 JP 2006-176602 A

  However, in the expandable styrenic polymer particles proposed in Patent Document 1, a glycerin fatty acid ester is preferably used in a liquid or paste form having a freezing point of 40 ° C. or less (paragraph number [0007]), When the expandable styrene polymer particles using such glycerin fatty acid ester were circulated in the particle distribution tube, the expandable styrene polymer particles collided with the curved portion of the particle distribution tube, in particular, the portion bent at a right angle. At this time, the glycerin fatty acid ester applied to the surface of the expandable styrene polymer particles easily adheres to the inner wall surface of the particle distribution tube in a wax shape.

  Furthermore, the glycerin fatty acid ester adhering to the inner wall surface of the particle distribution pipe helps exfoliation of the glycerin fatty acid ester and the metal salt of the fatty acid from the surface of the expandable styrenic polymer particles flowing through the particle distribution pipe. These stripped coatings gradually accumulate in the shape of a wax on the inner wall surface of the particle flow tube, resulting in a narrow flow space in the particle flow tube, and the flow rate of expandable styrene polymer particles and pre-expanded particles. There is a problem that the deposit is deposited in a wax shape on the inner wall surface of the particle distribution pipe and is detached from the inner wall surface, and the detached deposit is mixed into the foam molded product.

  Further, even in the expandable styrene resin particles proposed in Patent Document 2, the effect of reducing adhesion to the inner wall surface of the particle distribution pipe is not sufficient, and further reduction is required.

  The object of the present invention is to provide a foaming styrenic resin that suppresses the falling off of the coating material in the process of distribution to a pre-foaming machine, silo or foam molding machine, and has very little adhesion of the coating material to the inner wall surface of the particle distribution pipe (pipe). An object of the present invention is to provide a container for agricultural products using resin particles.

Thus, according to the agricultural product container of the present invention, a polystyrene foam molded article obtained by prefoaming expandable styrene resin particles obtained by impregnating a styrene resin particle with a foaming agent and molding the prefoamed particles. An agricultural container,
The foamable styrenic resin particles have the resin particle surface coated with a composition, and the composition comprises polyhydric alcohol A which is liquid at room temperature to coat the resin particle surface, and 100 parts by weight of the resin particles. 0.01 to 0.3 parts by weight of fatty acid monoglyceride, 0.03 to 0.3 parts by weight of fatty acid metal salt with respect to 100 parts by weight of the resin particles, and polyhydric alcohol B which is liquid at room temperature The polyhydric alcohols A and B contain 0.02 to 0.3 parts by weight with respect to 100 parts by weight of the resin particles, and are coated in two portions.
The polystyrene foamed molded is polystyrene resin particles having a particle diameter 600Myuemu～1400myuemu, the density of the polystyrene molded foam product is ^{0.01g / cm 3 ~0.033g / cm 3} , the polystyrene foam the average chord length of the molded body is 20Myuemu～150myuemu, agricultural containers, wherein the flexural strength of the polystyrene foamed molded is ^20N / cm ^{2 ~100N} / cm 2 is provided.

Thereby, there is no blocking at the time of pre-foaming, and further, the polyhydric alcohol is divided into two and coated as polyhydric alcohols A and B, so that the drug coated on the surface is difficult to peel off when the resin is transferred. The spreading effect can be improved.
In particular, even when the pre-foaming step or the flow process in the particle flow pipe (pipe), particularly when the particle flow pipe (pipe) is greatly bent, the coating agent is removed from the surface of the expandable styrene resin particles. Particle flow of expandable styrene resin particles and pre-expanded particles obtained by pre-expanding them can prevent accidental detachment or accumulation of waxy deposits on the inner wall of the particle distribution tube A smooth distribution in the pipe can be ensured, and an agricultural product container can be obtained as a foamed molded article having excellent antistatic properties.

It is the schematic which shows the suction conveyance apparatus of an expandable polystyrene resin particle. It is a numerical value which shows the particle size of an expandable polystyrene resin particle, and its distribution map.

Hereinafter, embodiments of the present invention will be described in more detail. In addition, the following description is applied to the expandable polystyrene resin particle which concerns on embodiment of this invention, and its manufacturing method.
(Styrene resin particles)
The styrene resin constituting the expandable styrene resin particles in the present invention is not particularly limited, but is a generally known styrene resin granule which is mainly composed of styrene, and is a homopolymer of styrene. However, styrene derivatives such as α-methylstyrene, paramethylstyrene, t-butylstyrene, chlorostyrene, esters of acrylic acid and methacrylic acid such as methyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, cetyl methacrylate, or dimethyl Copolymers with various monomers such as fumarate and ethyl fumarate may also be used. Moreover, you may use together polyfunctional monomers, such as divinylbenzene and alkylene glycol dimethacrylate. A weight average molecular weight of 150,000 to 400,000, preferably 250,000 to 350,000, which is generally usable as expanded polystyrene can be used.

  Here, as the method for producing the expandable styrene resin particles of the present invention, a general-purpose production method is used, and a foaming agent is contained in the aqueous suspension during suspension polymerization of the styrene resin, so that the styrene resin particles A method of producing expandable styrene resin particles by impregnating a foaming agent therein, a styrene resin particle is produced by a general-purpose method, and the styrene resin particles are impregnated with a foaming agent to produce expandable styrene resin particles. The manufacturing method etc. are mentioned. In addition, when impregnating a foaming agent at the time of suspension polymerization of a styrene-type resin, it is preferable to contain a foaming agent in aqueous suspension when the polymerization conversion rate of a monomer is 85 weight% or more.

  In addition, a polymerization initiator is used at the time of suspension polymerization of the styrene resin. As the polymerization initiator, a general-purpose one is used, for example, benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, orthochloro. Benzoyl peroxide, orthomethoxybenzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, cumene hydroperoxide, cyclohexanone peroxide, t-butyl hydroperoxide, t-butyl peroxybenzoate, t-butyl peroxybivalate , T-butylperoxyisopropyl carbonate, t-butylperoxyacetate, 2,2-t-butylperoxybutane, diisopropylbenzene hydroperio Peroxide-based polymerization initiators such as side, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2,3- Dimethylbutyronitrile), 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,3,3-trimethylbutyronitrile), 2,2'-azobis (2-isopropyl) Butyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2- (carbamoylazo) isobutyronitrile 4,4′-azobis (4-cyanovaleric acid), dimethyl-2,2′-azobisisobutyrate and the like.

  The particle diameter of the expandable styrene resin particles in the present invention is preferably between 600 μm and 1400 μm. If the thickness is less than 600 μm, the strength of the resulting molded product is lowered, which is not preferable. Here, a particle diameter means the value calculated | required by JISZ8815. As a method for obtaining particles of 600 μm to 1400 μm, particles obtained by a normal suspension polymerization method may be classified, or a suspension seed polymerization method may be used. It is preferable to use a suspension seed polymerization method because a higher yield can be obtained.

(Foaming agent)
The blowing agent used in the present invention is not particularly limited as long as it is conventionally used for producing expandable styrene resin particles. For example, propane, normal butane, isobutane, normal pentane, isopentane, neopentane. And aliphatic hydrocarbons such as normal hexane, and alicyclic hydrocarbons such as cyclobutane, cyclopentane, and cyclohexane. These may be used alone or in combination of two or more. The amount of the readily volatile foaming agent used in the present invention is 2 to 7% by weight. Preferably it is 3 to 6% by weight. If it is less than 2% by weight, the fusion rate during molding tends to decrease, which is not preferred. If it exceeds 7% by weight, the particle gap of the molded product tends to increase, and the surface beauty tends to be impaired, and molding is also difficult. Since the cycle becomes long, it is not preferable. These foaming agents may be added during the polymerization process of the expandable styrene resin particles, or may be added after the polymerization process is completed.

(Fatty acid monoglyceride)
The fatty acid monoglyceride used in the present invention is not particularly limited, and examples thereof include stearic acid monoglyceride, palmitic acid monoglyceride, behenic acid monoglyceride, 12-hydroxystearic acid monoglyceride, oleic acid monoglyceride, capric acid monoglyceride, and lauric acid monoglyceride. Of these, stearic acid monoglyceride (66 ° C.), palmitic acid monoglyceride (65 ° C.), behenic acid monoglyceride (80 ° C.), 12-hydroxystearic acid monoglyceride (74 ° C.), lauric acid having a melting point of 50-80 ° C. Monoglyceride (57 ° C.) is preferably used. When the melting point is 50 ° C. or less, when the expandable styrene resin particles and the pre-expanded particles obtained by pre-expanding the particles are distributed in the particle distribution pipe (pipe), the inner wall surface of the particle distribution pipe (pipe) It is not preferable because a waxy deposit tends to adhere. On the other hand, if the melting point exceeds 80 ° C., it is not preferable because the coating agent is easily detached from the surface of the expandable styrene resin particles. The melting point of the fatty acid monoglyceride here is the endothermic peak in the DSC curve obtained when the fatty acid monoglyceride is heated from 0 ° C. to 150 ° C. at a heating rate of 10 ° C./min by a differential scanning calorimeter. The temperature measured as the peak temperature.

  The amount of fatty acid monoglyceride used is preferably 0.01 to 0.3 parts by weight, more preferably 0.01 to 0.2 parts by weight, per 100 parts by weight of expandable styrene resin particles. If the amount is less than 0.01 parts by weight, the resulting molded article has insufficient antistatic performance and dirt is easily noticeable due to adhesion of dust. On the other hand, if the amount exceeds 0.3 parts by weight, the effect of increasing the amount added is not desirable. When the expandable styrene resin particles and the pre-expanded particles obtained by pre-expanding the particles are circulated in the particle distribution pipe (pipe), a waxy shape is formed on the inner wall surface of the particle distribution pipe (pipe). This is not preferable because deposits are likely to be deposited.

(Fatty acid metal salt)
Examples of the fatty acid metal salt include zinc stearate, calcium stearate, magnesium stearate, aluminum stearate, zinc laurate, and calcium laurate. Among these, zinc stearate is preferably used. Normally, the fatty acid constituting the commercially available zinc stearate is a mixture of stearic acid as a main component and palmitic acid, myristic acid, lauric acid, arachidic acid, behenic acid, etc., and zinc stearate in the present invention Also, such a commercial product can be used.
The amount of fatty acid metal salt used is preferably 0.03 to 0.3 parts by weight, more preferably 0.05 to 0.2 parts by weight, based on 100 parts by weight of expandable styrene resin particles. When the amount is less than 0.03 parts by weight, blocking between the resin particles at the time of pre-expansion of the expandable styrene resin particles may occur, or the heat-fusibility between the expanded particles may be deteriorated. On the other hand, when the amount exceeds 0.3 parts by weight, the effect of increasing the addition amount is not so much seen, and when the expandable styrene resin particles and the pre-expanded particles obtained by pre-expanding the particles are circulated in the particle distribution pipe This is not preferable because waxy deposits are easily deposited on the inner wall surface of the particle distribution tube.

(Polyhydric alcohol)
In the present invention, a spreading effect is imparted by using fatty acid monoglyceride and using a polyhydric alcohol that is liquid at room temperature as polyhydric alcohols A and B twice.
The polyhydric alcohol is not particularly limited as long as it is liquid at room temperature. For example, ethylene glycol, diethylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, higher polyethylene glycols, propylene glycol, di-ethylene Examples include propylene glycol, higher polypropylene glycols, glycerin, diglycerin, and higher polyglycerins, among which inexpensive polyethylene glycol is particularly preferable.

  Furthermore, it is preferable to use a polyhydric alcohol having a viscosity of 30 to 80 cp, more preferably 40 to 70 cp. When the viscosity is less than 30 cp, the adhesion effect is weak and much of the coated drug is peeled off during the transfer. On the other hand, when the viscosity exceeds 80 cp, the viscosity becomes too high, so that the particles are sticky, and a large amount of the coated drug is peeled off during transport. Here, the viscosity of the polyhydric alcohol means a value measured at 25 ° C. with a B-type viscometer (BL type, rotor No. 2, rotation speed 60 rpm, after 30 seconds).

  The polyhydric alcohol is contained in an amount of 0.02 to 0.3 parts by weight with respect to 100 parts by weight of the resin particles, and is coated as polyhydric alcohols A and B in two portions. That is, the amount of polyhydric alcohol used is preferably 0.01 to 0.15 parts by weight with respect to 100 parts by weight of expandable styrene resin particles in the first coating (polyhydric alcohol A), and 0.02 to 0 0.08 parts by weight is more preferable. If it is less than 0.01 parts by weight, the antistatic effect is low and there is a risk of ignition due to static electricity or the like during use. On the other hand, adding more than 0.15 parts by weight is not preferable because an effect commensurate with the addition is not seen and the powder coating tends to be non-uniform due to the stickiness of the particles. The second coating (polyhydric alcohol B) is preferably from 0.01 to 0.15 parts by weight, more preferably from 0.02 to 0.08 parts by weight, based on 100 parts by weight of the expandable styrene resin particles. If the amount is less than 0.01 parts by weight, the spreading effect is weak and the coated drug may be peeled off during the transfer. On the other hand, if the amount is more than 0.15 parts by weight, the particles are sticky and the coated drug is transferred. It is not preferable because a large amount of peeling occurs inside.

  The first coating with polyhydric alcohol (polyhydric alcohol A) may be mixed for a fixed time in a mixer such as a Laedige mixer or sprayed in a line from immediately after dehydration to the mixer. Thereafter, a fatty acid monoglyceride or a fatty acid metal salt is mixed and coated. The fatty acid monoglyceride and the fatty acid metal salt may be coated by mixing them both as described in JP-A-2006-176602 or separately. When coating separately, it is preferable to coat the fatty acid metal salt after coating the fatty acid monoglyceride. Finally, it is preferable that the second coating with polyhydric alcohol (polyhydric alcohol B) is mixed and coated for a certain period of time in a mixer.

  In addition, a general-purpose mixing apparatus can be used as the mixer, for example, a container-fixing type mixing apparatus such as a Henschel mixer, a super mixer, a Ladige mixer, or a ribbon blender, or a container such as a tumbler mixer or a V-type blender. Examples include a rotary mixing device.

(Pre-foaming method for expandable styrene resin particles)
As the pre-foaming method for the expandable styrene resin particles in the present invention, a conventionally known method can be used. For example, pre-expanded particles having a bulk density of about 0.01 to 0.05 g / cm ³ can be obtained by heating with water vapor in a rotary stirring pre-foaming apparatus. Moreover, the obtained pre-expanded particles are filled in a mold having a desired shape and heated with water vapor or the like to obtain a foam-molded product.

(Molding)
Since the molded product obtained by pre-foaming and molding the expandable styrene resin particles of the present invention is excellent in antistatic properties, it can be used in agricultural products containers as molded products that are resistant to contamination.
In addition, 20-150 micrometers is preferable and, as for the average chord length of the said foaming molding, 50-120 micrometers is more preferable. This is because when the average chord length of bubbles in the foamed molded product is small, the number of the bubble walls in the foamed molded product, that is, the surface area of the cell walls increases too much, and the thickness of each cell wall becomes thin. Although the number increases and the number of times of heat blocking increases, the degree of decrease in the heat blocking effect by the cell walls increases, and as a result, shrinkage of the foamed molded body increases. On the other hand, when the average chord length of the foamed molded product is large, the total number of bubbles in the thickness direction of the foamed molded product decreases, and as a result, the strength of the foamed molded product decreases.
When the density of the foamed molded product is low, the closed cell ratio of the polystyrene resin foam molded product is lowered, and the thermal insulation and mechanical strength of the polystyrene resin foam molded product may be lowered, Since the time required for one cycle in the in-mold foam molding becomes long and the production efficiency of the polystyrene-based resin foam molding may be lowered, 0.01 to 0.033 g / cm ³ is preferable.
When the bending strength of the foamed molded product is low, there is a risk of deformation when the polystyrene-based resin foamed molded product is stacked and used, while when it is high, the production efficiency of the polystyrene-based resin foamed molded product may be reduced. Therefore, it is not preferable. Therefore, the bending strength of the foamed molded product ^{is 20N / cm 2 ~100N / cm 2} .

Hereinafter, although an example and a comparative example explain the present invention, the present invention is not limited to this.
(Particle size measurement)
A JIS standard sieve opening of 1.7 mm, 1.4 mm, 1.18 mm, 1.0 mm, 0.85 mm, 0.71 mm, 0.6 mm, and 0.5 mm was classified to obtain a cumulative weight distribution curve.

(Viscosity measurement)
The polyhydric alcohol was transferred to the shoulder of a 200 ml standard bottle and measured at 25 ° C. using the B-type viscometer (BL type, rotor No. 2, rotation speed 60 rpm, after 30 seconds) manufactured by Tokyo Keiki. .

Example 1
8 kg of expandable polystyrene particles having a particle size of 0.6 to 1.2 mm containing 5.5% by weight of butane as a foaming agent and 0.5% by weight of diisobutyl adipate as a foaming aid were added to a Ladige mixer (Matsuda Giken Co., Ltd.). The product name “M20” manufactured by the company was added to 100 parts by weight of expandable polystyrene particles, and polyethylene glycol (trade name “PEG-300” manufactured by Sanyo Chemical Industries, Ltd., viscosity 62 0.5 cp) 0.04 part by weight was added and stirred at 230 rpm for 2 minutes, and then 0.05 part by weight of stearic acid monoglyceride (trade name “Riquemar S-100P” manufactured by Riken Vitamin Co., Ltd.) shown in Table 1 was added. , And stirred for 3 minutes at 230 rpm, and further zinc stearate shown in Table 1 (trade name “Dye Wax ZF” manufactured by Dainichi Chemical Industry Co., Ltd.) 0.1 weight Then, the mixture was stirred at 230 rpm for 3 minutes, and then 0.04 part by weight of polyethylene glycol (trade name “PEG-300”, viscosity 62.5 cp, manufactured by Sanyo Chemical Industries, Ltd.) as the polyhydric alcohol B shown in Table 1 again. And stirring at 230 rpm for 5 minutes to obtain coated expandable polystyrene particles.
When the particle diameter (particle size distribution) of the coated expandable polystyrene particles was measured, the average particle diameter D _50% was 0.9042 mm and the 1.180 mm (fifth) was 0.02 as shown in FIG. %, 1.000 mm (third) is 4.78%, 0.850 mm (max) is 70.80%, 0.710 mm (second) is 24.32%, and 0.600 mm (fourth) is 0.8. A particle size (particle size distribution) of 08% was obtained.

(Example 2)
Foam coated in the same manner as in Example 1, except that the polyethylene glycols of the polyhydric alcohols A and B were replaced with propylene glycol (trade name “propylene glycol” manufactured by Asahi Glass Co., Ltd., viscosity 42.7 cp) in Example 1. Polystyrene particles were obtained.

(Example 3)
In Example 1, the polyethylene glycols of the polyhydric alcohols A and B were the same as in Example 1 except that the low viscosity polyethylene glycol (trade name “PEG-200”, viscosity 46.9 cp, manufactured by Sanyo Chemical Industries, Ltd.) was changed. Thus, expandable polystyrene particles coated were obtained.

(Example 4)
In Example 1, the addition amount of polyhydric alcohol A is 0.02 parts by weight, the addition amount of stearic acid monoglyceride is 0.03 parts by weight, the addition amount of zinc stearate is 0.05 parts by weight, Exfoliated polystyrene particles coated were obtained in the same manner as in Example 1 except that the amount added was changed to 0.02 parts by weight.

(Example 5)
In Example 1, the addition amount of polyhydric alcohol A is 0.1 parts by weight, the addition amount of stearic acid monoglyceride is 0.15 parts by weight, the addition amount of zinc stearate is 0.25 parts by weight, Exfoliated polystyrene particles coated were obtained in the same manner as in Example 1 except that the amount added was changed to 0.1 parts by weight.

(Example 6)
In the same manner as in Example 1 described in JP-A-2006-176602, a coating agent (coating agent A) in which zinc stearate was adhered to the surface of stearic acid monoglyceride was produced.
Next, 5.5% by weight of butane as a foaming agent and 0.2% of diisobutyl adipate as a foaming aid. 8 kg of expandable polystyrene particles containing 5% by weight and having a particle diameter of 0.6 to 1.2 mm are put into a Laedige mixer (trade name “M20” manufactured by Matsuda Giken Co., Ltd.), and further expandable polystyrene particles 100 0.04 part by weight of polyethylene glycol (trade name “PEG-300” manufactured by Sanyo Chemical Industries, Ltd., viscosity 62.5 cp) manufactured by Sanyo Chemical Industries, Ltd.) is added as the polyhydric alcohol A shown in Table 1 with respect to parts by weight and stirred at 230 rpm for 2 minutes did. Thereafter, 0.1 part by weight of coating agent A and zinc stearate (trade name “Die Wax ZF” manufactured by Dainichi Chemical Industry Co., Ltd., 0.05 part by weight) were sequentially added and stirred at 230 rpm for 5 minutes. Polyethylene glycol (trade name “PEG-300” manufactured by Sanyo Chemical Industries, Ltd., viscosity 62.5 cp) 0.04 part by weight is added as the polyhydric alcohol B shown, and the mixture is stirred at 230 rpm for 5 minutes, and coated expandable polystyrene particles Got.

(Example 7)
In Example 1, expandable polystyrene particles coated in the same manner as in Example 1 except that stearic acid monoglyceride was replaced with 12-hydroxystearic acid monoglyceride (trade name “Riquemar HC-100” manufactured by Riken Vitamin Co., Ltd.). Obtained.

(Example 8)
In Example 1, the addition amount of polyhydric alcohol A is 0.01 parts by weight, the addition amount of stearic acid monoglyceride is 0.01 parts by weight, the addition amount of zinc stearate is 0.03 parts by weight, Exfoliated polystyrene particles coated were obtained in the same manner as in Example 1 except that the amount added was changed to 0.01 parts by weight.

Example 9
In Example 1, the amount of polyhydric alcohol A added was 0.15 parts by weight, the amount of stearic acid monoglyceride added was 0.3 parts by weight, the amount of zinc stearate added was 0.3 parts by weight, and the amount of polyhydric alcohol B Expanded polystyrene particles coated in the same manner as in Example 1 were obtained except that the addition amount was changed to 0.15 parts by weight.

(Comparative Example 1)
In Example 1, expandable polystyrene particles coated in the same manner as Example 1 were obtained except that polyhydric alcohols A and B were not added.

(Comparative Example 2)
In Example 1, expandable polystyrene particles coated in the same manner as in Example 1 were obtained except that polyhydric alcohol A was not added and the amount of polyhydric alcohol B added was changed to 0.08 parts by weight. .

(Comparative Example 3)
In Example 1, expandable polystyrene particles coated in the same manner as in Example 1 were obtained except that the amount of polyhydric alcohol A added was 0.08 parts by weight and polyhydric alcohol B was not added. .

(Comparative Example 4)
In Example 1, expandable polystyrene particles coated were obtained in the same manner as in Example 1 except that the addition amount of polyhydric alcohols A and B was changed to 0.2 parts by weight.

(Comparative Example 5)
In Example 1, expandable polystyrene particles coated in the same manner as in Example 1 were obtained except that the addition amount of the polyhydric alcohols A and B was changed to 0.004 parts by weight.

(Comparative Example 6)
In Example 1, the polyethylene glycols of the polyhydric alcohols A and B were the same as in Example 1 except that the polyethylene glycol of high viscosity was changed to a high viscosity polyethylene glycol (trade name “PEG-600”, viscosity: 120.2 cp manufactured by Sanyo Chemical Industries, Ltd.) Thus, expandable polystyrene particles coated were obtained.

(Comparative Example 7)
In Example 1, expandable polystyrene particles coated were obtained in the same manner as in Example 1 except that the amount of zinc stearate added was changed to 0.01 parts by weight.

(Comparative Example 8)
In Example 1, expandable polystyrene particles coated were obtained in the same manner as in Example 1 except that the amount of stearic acid monoglyceride added was changed to 0.001 part by weight.

(Comparative Example 9)
In Example 1, expandable polystyrene particles coated were obtained in the same manner as in Example 1 except that the addition amount of stearic acid monoglyceride was changed to 0.35 parts by weight.

(Comparative Example 10)
In Example 1, expandable polystyrene particles coated were obtained in the same manner as in Example 1 except that the amount of zinc stearate added was changed to 0.35 parts by weight.

  Pipe adhesion of the obtained expandable polystyrene particles, blocking property during preliminary foaming, and chargeability of the molded product were measured as described below. The results are shown in Table 1.

(Piping adhesion)
Pipe adhesion of expandable polystyrene resin particles was evaluated using a suction transport device ML-5500CB manufactured by MEL Engineering.

  FIG. 1 is a schematic diagram showing a suction transport device ML-5500CB manufactured by MEL Engineering. In FIG. 1, 1 is a hopper, 2 is a suction part provided in the upper part. The hopper 1 is provided with a discharge pipe 11, and the suction part 2 is provided with an introduction pipe 21 having an inner diameter of 46 mm. Reference numeral 5 denotes a blower that sucks air from the suction portion 2 through the suction tube 3 through the bag filter 4 with suction air. Reference numeral 6 denotes a tank provided directly below the discharge pipe 11. The tank 6 is provided with a suction pipe 61 having an inner diameter of 46 mm. 7 is a metal pipe having an inner diameter of 46 mm and a length of 1.4 m arranged perpendicular to the ground. A resin hose having an inner diameter of 50 mm and a length of 1 m is attached to both ends of the metal pipe 7, and the other of the resin hoses is attached to the introduction pipe 21 and the suction pipe 61, respectively. In this state, 8 kg of expandable polystyrene resin particles A coated in the tank 6 were charged and sucked for 30 seconds at a flow rate of 200 g / second. While the suction was stopped for 15 seconds, 8 m of the expandable polystyrene resin particles A filled in the hopper 1 were dropped and received in the tank 6. After repeating this suction circulation 80 times, the resin hose 8 was removed and the weight was measured, and the amount of resin hose attached was determined from the weight difference before and after the evaluation. Also, the deposit on the introduction pipe 21 was scraped off and the weight was measured to determine the amount of metal pipe deposited. About each, pipe | tube adhesiveness was evaluated based on the following reference | standard.

(Blocking property)
Using a pre-foaming machine having an internal volume of 25 liters equipped with a stirrer, the foamable polystyrene particles after pipe adhesion evaluation were pre-foamed to a bulk magnification of 60 times with 0.05 MPa water vapor, and the obtained pre-foamed particles were Sieve using a sieve with an opening of 10 mm specified in JIS, measure the weight of the binding particles formed by joining the pre-expanded particles remaining on the sieve, and the amount of the binding particles relative to the total amount of the pre-expanded particles The weight percentage was calculated, and the blocking property was evaluated based on the following criteria.
○ ・ ・ ・ less than 1% by weight × ・ ・ ・ 1% by weight or more

(Antistatic property)
Using expandable polystyrene particles after pipe adhesion evaluation, expandable polystyrene particles were pre-expanded to a bulk magnification of 60 times with water vapor of 0.05 MPa using a pre-expanding machine equipped with a stirrer and having an internal volume of 25 liters. . The obtained pre-expanded particles were sieved using a sieve having an opening of 10 mm specified in JIS, and the pre-expanded particles that passed through the sieve were allowed to stand and dry at 23 ° C. under atmospheric pressure for 24 hours. . Next, the pre-expanded particles are filled into a mold for forming agricultural products containers, and the pre-expanded particles are heated and foamed with water vapor at a pressure of 0.07 MPa for 30 seconds to secondary-expand the pre-expanded particles. The foamed particles obtained by secondary foaming of the foamed particles are heat-fused and integrated, and then cooled to form a foamed molded product having a length of 340 mm × width of 670 × height of 250 mm and a wall thickness of about 20 mm, and at 30 ° C. for 24 hours Dried. The same operation was repeated to produce five agricultural product containers.

Next, at 25 ° C. and 50% RH, the amount of charge on the side portions of the five agricultural product containers was measured using a static electricity meter (FMX-003 manufactured by Simco Japan). The maximum value is shown in Table 1, and the antistatic property was evaluated based on the following criteria.
○ ・ ・ ・ Maximum value is less than 0.1 kV × ・ ・ ・ Maximum value is 0.1 kV or more

(Molded body density)
The density of the foamed molded product was calculated by the following equation by measuring the weight of the agricultural product container, then immersing the agricultural product container in water, and taking the volume difference of water before and after immersion as the test piece volume.
Density (g / cm ³ ) = Test specimen weight (g) / Test specimen volume (cm ³ )

(Average chord length of molded body)
The average chord length of a container for agricultural products refers to that measured according to the test method of ASTM D2842-69. Specifically, the foamed molded body is cut into approximately equal halves, and the cut surface is photographed at a magnification of 100 times using a scanning electron microscope (trade name “S-3000N” manufactured by Hitachi, Ltd.). To do. The photographed image is printed on A4 paper, and a straight line with a length of 60 mm is drawn at an arbitrary position. From the number of bubbles existing on this straight line, the average chord length (t) of the bubbles is calculated by the following equation.
Average string length t = 60 / (number of bubbles × photo magnification)
When drawing a straight line, if the straight line would make point contact with the bubble as much as possible, this bubble was included in the number of bubbles, and both ends of the straight line were positioned within the bubble without penetrating the bubble. In the case of the state, the bubble in which both ends of the straight line are located is included in the bubble number. Further, the average chord length is calculated in the same manner as described above at any five locations in the photographed image, and the arithmetic average value of these average chord lengths is set as the average chord length of the agricultural product container.

(Bending strength of molded body)
The bending strength was measured according to the method described in JIS A9511: 1995 “Foamed plastic heat insulating material”. Specifically, using Tensilon universal testing machine UCT-10T (Orientec Co., Ltd.), the container for agricultural products after antistatic property evaluation was cut into a rectangular parallelepiped of 75 × 300 × 20 mm in thickness to obtain a test piece. Was measured at 10 mm / min.

  The container for agricultural products of the present invention is a surface of the expandable styrenic resin particles, especially in the pre-foaming step and the distribution process in the particle distribution pipe, particularly when the particle distribution pipe is greatly bent. Can be prevented from unexpectedly detaching or depositing wax-like deposits on the inner wall surface of the particle distribution pipe. The expandable styrenic resin particles and the pre-expanded particles obtained by pre-expanding the particles can be prevented. A smooth distribution in the particle distribution pipe can be ensured, and an agricultural product container can be obtained as a foamed molded article having excellent antistatic properties.

DESCRIPTION OF SYMBOLS 1 Hopper 11 Release pipe 2 Suction part 3 Suction pipe 4 Bag filter 5 Blower 6 Tank 7 Metal piping 8 Resin hose

Claims (3)

A pre-expanded expandable styrene-based resin particle obtained by impregnating a styrene-based resin particle with a foaming agent, and a polystyrene-based foam molded product obtained by molding the pre-expanded particle,
The foamable styrenic resin particles have the resin particle surface coated with a composition, and the composition comprises polyhydric alcohol A which is liquid at room temperature to coat the resin particle surface, and 100 parts by weight of the resin particles. 0.01 to 0.3 parts by weight of fatty acid monoglyceride, 0.03 to 0.3 parts by weight of fatty acid metal salt with respect to 100 parts by weight of the resin particles, and polyhydric alcohol B which is liquid at room temperature The polyhydric alcohols A and B are contained in an amount of 0.02 to 0.3 parts by weight based on 100 parts by weight of the resin particles, and after coating the liquid polyhydric alcohol A at room temperature, the resin particles 100 weights. 0.01 to 0.3 parts by weight of fatty acid monoglyceride with respect to 100 parts by weight, and 0.03 to 0.3 parts by weight of fatty acid metal salt with respect to 100 parts by weight of the resin particles, and a liquid polyvalent at room temperature Covered with alcohol B It has been,
The polystyrene foamed molded is polystyrene resin particles having a particle diameter 600Myuemu～1400myuemu, the density of the polystyrene molded foam product is ^{0.01g / cm 3 ~0.033g / cm 3} , the polystyrene foam the average chord length of the molded body is 20Myuemu～150myuemu, agricultural containers flexural strength of the polystyrene foamed molded is ^{20N / cm 2 ~100N / cm 2} .   2. The agricultural product container according to claim 1, wherein the polyhydric alcohol that is liquid at room temperature is polyethylene glycol. The container for agricultural products according to claim 1 or 2, wherein the fatty acid metal salt is zinc stearate.

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