JP2012067175A - Method for removing volatile organic compound, method for producing polystyrene-based resin foam sheet, and method for producing container for food - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide methods for removing a volatile organic compound effective in removing a volatile organic compound from resin particles containing a polyphenylene ether-based resin, to consequently provide a method for producing a polystyrene-based resin foam sheet containing a polyphenylene ether-based resin, and to improve problems of odors in a method for producing a container for foods using the polystyrene-based resin foam sheet.SOLUTION: There are provided the methods for removing the volatile organic compound including removing the volatile organic compound from the resin particles containing the polyphenylene ether-based resin. Furthermore, there are provided the methods etc., for removing the volatile organic compound including fluidizing the resin particles in a gas at a higher temperature than T-70(°C) when the glass transition temperature of the resin particles is T(°C), thereby releasing the volatile organic compound contained in the resin particles into the gas, and removing the volatile organic compound.

Description

  The present invention relates to a method for removing a volatile organic compound from a resin particle containing a polyphenylene ether resin, a polystyrene resin foam sheet for extruding and foaming a raw material containing a resin particle containing a polyphenylene ether resin. And a method for producing a food container for producing a food container by thermoforming a polystyrene-based resin foam sheet.

  Conventionally, a polystyrene-based resin pellet and a master batch containing an air conditioner are supplied to an extruder and melt-kneaded with a foaming agent such as a hydrocarbon in the extruder, and then the melt-kneaded product is extruded into the extruder. A polystyrene resin foam sheet is continuously produced by extrusion foaming from a flat die or a circular die attached to the end of the machine, and the resulting polystyrene resin foam sheet is thermoformed to produce containers such as food trays. It is widely done.

  The polystyrene-based resin foam sheet is used alone to form a food container, or is used to form a food container after a resin film is laminated on the surface. For example, instant noodles are accommodated. In applications where a certain level of strength is required, such as containers, it is difficult to satisfy the requirements for strength by forming a container shape with a single polystyrene resin foam sheet. It has been attempted to improve the strength of the container by laminating a polystyrene resin film or a polypropylene resin film.

In food containers and the like, there is a strong demand for heat resistance as well as strength, and it is required to improve the heat distortion temperature.
In response to such demands, it has been conventionally studied to improve the thermal deformation temperature of a product by adding a polyphenylene ether resin to the raw material of the polystyrene resin product (see Patent Document 1 below).
Although this polyphenylene ether resin itself is commercially available in a powder state, the polyphenylene ether resin itself has low fluidity even at temperatures above the melting point and is difficult to handle. In the manufacturer, a mixed resin pellet with a highly compatible resin such as a polystyrene resin is prepared in advance, and most of the polyphenylene ether resin is used in the state of the mixed resin pellet.
And when producing polystyrene-based resin foam sheets that require heat resistance, the blended resin pellets and polystyrene-based resin pellets are blended at a predetermined ratio, and the proportion of polyphenylene ether resin contained in the product is adjusted. It has been widely done in the past.

In addition, it is known that a polyphenylene ether resin contains a volatile organic compound and emits an odor by the volatile organic compound.
Such odor generation is observed not only in powdered resin particles made of a single polyphenylene ether resin but also in pelletized resin particles made of the mixed resin, and is common to resin particles containing polyphenylene ether resin. It can be seen.
Therefore, when producing a polystyrene resin foam sheet with improved heat resistance by adding a polyphenylene ether resin, odor is generated from the mixed resin pellet itself, and from the extruded polystyrene resin foam sheet. In addition, a strong odor derived from the volatile organic compound is generated and the working environment may be deteriorated as compared with the case of producing a general polystyrene resin foam sheet.
Furthermore, a molded product such as a food container in which a polystyrene resin foam sheet is thermoformed may be caused to emit odor.
In contrast, for example, in Patent Document 1 below, hydrophobic zeolite is deodorized when a polystyrene resin foam sheet is produced by extrusion foaming a raw material containing a polyphenylene ether resin and a polystyrene resin. It describes that a predetermined amount is contained in the raw material as an agent to suppress the odor of the polystyrene resin foam sheet.

JP 2008-094919 A

As described in Patent Document 1, the method of adsorbing a volatile organic compound on a hydrophobic zeolite can obtain a certain deodorizing effect, but when an inorganic powder such as a hydrophobic zeolite is added, the hydrophobic zeolite It may function like a bubble regulator and may affect the foamed state of the polystyrene resin foam sheet.
Even when a non-foamed molded product is formed, the hydrophobic zeolite may affect the physical properties of the molded product.
For these reasons, it has been difficult to incorporate a hydrophobic zeolite into the raw material of a polystyrene resin foam sheet with a certain amount or more, and the deodorizing effect on the polystyrene resin foam sheet is also limited. Is caused.
In addition, the method of adding hydrophobic zeolite is expected to have a certain effect on deodorization of mixed resin pellets and polystyrene resin foam sheets, but there are powdered resin particles consisting only of polyphenylene ether resin particles. It cannot be used to suppress odors.

Here, if it is possible to remove the volatile organic compound directly from the resin particles containing the polyphenylene ether resin, it is possible to improve the production work environment of the polystyrene resin foam sheet and to obtain a product obtained in the past. It can be expected that the above deodorizing effect is exhibited.
However, an effective method for removing a volatile organic compound from a resin particle containing a polyphenylene ether resin has not been found so far, and it is difficult to expect such an effect.
Therefore, conventionally, it is difficult to improve the working environment for producing a polystyrene resin foam sheet containing a polyphenylene ether resin and a food container obtained by thermoforming such a polystyrene resin foam sheet. It has become.

  In view of the above problems, the present invention provides a method for removing a volatile organic compound that is effective for removing a volatile organic compound from a resin particle containing a polyphenylene ether-based resin. It is an object to improve the problem of odor in a method for producing a polystyrene-based resin foam sheet containing a resin and a method for producing a food container using such a polystyrene-based resin foam sheet.

  As a result of intensive investigations on a method for removing volatile organic compounds from resin particles containing a polyphenylene ether resin, the present inventor has made the resin particles flow to make them volatile from the resin particles into the surrounding gas. The present inventors have found that organic compounds are emitted and that the emission of volatile organic compounds can be further promoted by increasing the temperature of the gas to a predetermined level or higher, thereby completing the present invention.

  That is, the present invention related to a method for removing a volatile organic compound is a method for removing a volatile organic compound from a resin particle containing a polyphenylene ether resin, the glass transition temperature of the resin particle. When T is set to T (° C.), the resin particles are caused to flow in a gas at a temperature higher than T-70 (° C.) to release volatile organic compounds contained in the resin particles into the gas. It is characterized by being removed.

  In addition, the present invention relating to a method for producing a polystyrene resin foam sheet performs a reduction process of a volatile organic compound on a resin particle containing a polyphenylene ether resin by the method for removing a volatile organic compound as described above. The polystyrene resin foam sheet is produced by extruding and foaming the raw material containing the obtained resin particles, and the present invention relating to the method for producing a food container is characterized in that the polystyrene resin foam sheet is as described above. It is characterized by producing a food container by thermoforming a polystyrene-based resin foam sheet produced by the production method.

According to the method for removing a volatile organic compound of the present invention, since many volatile organic compounds are removed from the resin particles containing the polyphenylene ether resin, the odor emitted by the resin particles can be reduced.
Therefore, the working environment when producing a polystyrene-based resin foam sheet by extruding and foaming the raw material containing the resin particles, and the generation of odor when producing the food container by thermoforming the polystyrene-based resin foam sheet Can be suppressed.

The schematic block diagram of the removal equipment of a volatile organic compound.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
In general, a polyphenylene ether resin is generally represented by the following general formula.

Here, R ¹ and R ² represent an alkyl group having 1 to 4 carbon atoms or a halogen atom, and n is a positive integer representing the degree of polymerization.
For example, poly (2,6-dimethylphenylene-1,4-ether), poly (2,6-diethylphenylene-1,4-ether), poly (2,6-dichlorophenylene-1,4-ether) Ether) and the like are known.
The degree of polymerization n is usually in the range of 10 to 5000.

Such resin particles consisting only of polyphenylene ether resins contain volatile organic compounds such as toluene and ethylbenzene, and are decomposed by thermal decomposition or the like, butylamine, butanenitrile, butylmethylamine, butyldimethylamine, normal. It may generate volatile organic compounds such as butyric acid and dibutylamine.
Also, for example, if the resin particles are mixed resin pellets in which a polyphenylene ether resin and a polystyrene resin are previously melt-kneaded, the resin particles usually have a volatile property such as a styrene monomer derived from a polystyrene resin. An organic compound will be further contained.

In addition to the styrene homopolymer, the polystyrene resin includes, for example, styrene-based monomers such as methylstyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, paramethylstyrene, chlorostyrene, bromostyrene, vinyltoluene, and vinylxylene. A homopolymer of a monomer is known, and a copolymer of such a styrene monomer and another monomer is widely used as a polystyrene resin.
Therefore, if it is a mixed resin particle of these polystyrene resin and polyphenylene ether resin, the above-mentioned monomer and components such as dimer and trimer by the monomer are also contained in the resin particle as a volatile organic compound. May be.
The method for removing a volatile organic compound in the present embodiment is performed to remove the above-described components and to debromide the resin particles with respect to resin particles containing a polyphenylene ether resin. .

In addition, generation | occurrence | production of the odor component derived from a polyphenylene ether resin by applying the removal method of the volatile organic compound of this embodiment with respect to the resin particle which consists only of a polyphenylene ether resin among the above components Can be reduced more effectively.
In addition, since resin particles composed of a mixed resin of a polyphenylene ether resin and a polystyrene resin contain a large amount of components such as a styrene monomer, the volatile organic compound of the present embodiment with respect to the mixed resin particles. By applying the removal method, not only the volatile organic compound derived from the polyphenylene ether resin but also the volatile organic compound derived from the polystyrene resin can be removed together.

First, an example of deodorizing equipment for performing a reduction process of a volatile organic compound on the resin particles containing the above polyphenylene ether resin will be described.
FIG. 1 is a schematic configuration diagram showing a deodorizing facility used for removing a volatile organic compound, and reference numeral 1 in the drawing contains resin particles containing a polyphenylene ether resin, and the resin particles contained therein. 2 represents a chamber for removing volatile organic compounds from
Reference numeral 2 represents a blower for sending air into the chamber 1, and reference numeral 3 represents a heat exchanger for heating the air sent from the blower 2 to the chamber 1.
In the following description, “resin particles” means “resin particles containing a polyphenylene ether-based resin” unless otherwise specified.

The chamber 1 has a main body made of a cylindrical container placed vertically, and a partition plate 10 for partitioning an internal space up and down is provided inside the container.
The partition plate 10 is made of a breathable member such as punching metal or wire mesh so that air can travel between the upper space 1a and the lower space 1b partitioned by the partition plate 10. Is provided.
The upper space 1a is a space for accommodating the resin particles A, and the lower space 1b is used as a space for sending air sucked from the atmosphere by the blower 2.

  The upper space 1a has an inner diameter substantially the same as that of the lower space 1b in a fixed region near the partition plate 10, but is enlarged in the middle in the vertical direction, and the lower space 1b A larger-diameter region is formed above a region having substantially the same inner diameter (hereinafter, the smaller-diameter portion on the lower side is referred to as “small-diameter region (1a ′)”, and the larger-diameter portion on the upper side. Is also referred to as “large diameter region (1a ″)”).

  The deodorizing equipment in this embodiment is further provided with an intake path L1 for allowing the blower 2 to suck air and an air supply path L2 leading from the air outlet of the blower 2 to the lower space 1b. The heat exchanger 3 is installed in the middle of the air supply path L2, and is provided so as to heat the air supplied to the lower space 1b through the air supply path L2.

Further, the deodorization equipment in the present embodiment is further provided with an exhaust path L3 for releasing the air in the upper space 1a from the large-diameter region 1a ″ at the upper end thereof to the outside of the system.
That is, the chamber 1 in the present embodiment is formed so that air introduced into the lower space 1b can form an upward flow in the upper space 1a and can be exhausted outside the system through the exhaust path L3. By making the upper side of the diameter larger, even if the resin particles are swung up by the upward flow, the flow velocity of the air can be lowered in this large diameter region 1a ″ so that the resin particles can be dropped. Is formed.

As a method for deodorizing the resin particles using such a deodorizing equipment, for example, a fine mesh screen that does not allow the resin particles A to pass therethrough is used as a constituent member of the partition plate 10, and the upper space Resin particles can be accommodated in the small-diameter region 1a ′ in 1a, and the blower 2 can generate an air flow F that is an upward flow in the chamber 1 for the implementation.
At this time, the resin particles A are lifted from the lower side by the wind pressure of the air flow F and stirred to form a so-called fluidized bed, and the temperature of the air passing between the resin particles in the fluidized bed is configured to form the resin particles A. From the resin particles A, the temperature of the heat exchanger 3 can be adjusted to be higher than T-70 (° C.) when the glass transition temperature of the resin composition is T (° C.). This is important for efficiently removing volatile organic compounds.

By causing the resin particles to flow in this manner, the surface of the resin particles is exposed to the air containing almost no volatile organic compound, and the volatile organic compound contained in the resin particles causes the resin particles to be removed. It will be released into the surrounding gas.
Moreover, the diffusion rate of the volatile organic compound in the resin particle can be improved by setting the temperature of the air passing between the particles of the resin particle as described above, and the volatile organic compound can be more efficiently converted into the resin particle. It can be released outside.

At this time, the volatile organic compound can be removed in a shorter time when the temperature is higher, and the volatile organic compound can be efficiently removed. On the other hand, if the temperature is excessively high, especially in the case of mixed resin pellets, resin particles There is a risk of sticking to each other.
From such a viewpoint, it is preferable that the temperature of the air passing between the resin particles is lower than the softening temperature of the resin particles.
That is, when the softening temperature of the resin particles is T ₁ (° C.) and the temperature of the air passing between the resin particles is T ₀ (° C.), the temperature of the air (T ₀ ) is expressed by the following relational expression ( It is preferable to satisfy 1).

(T-70 ° C.) <T ₀ <T ₁ (1)

In addition, about the glass transition temperature (T) of this resin particle, it can obtain | require based on JISK7121 9.3 (1), and can obtain | require it by measuring "mid-point glass transition temperature (Tmg)".
For example, a sample of about 6.5 ± 0.5 mg is collected from resin particles, and the sample is set in a differential scanning calorimeter device, model name “DSC6220” manufactured by SII NanoTechnology Co., Ltd. The differential based on JIS K7121 It can be determined by performing a scanning calorimetric analysis.

The softening temperature (T ₁ ) can be determined by thermomechanical analysis (TMA), and is determined according to the method described in JIS K7196 “Softening temperature test method by thermomechanical analysis of thermoplastic film and sheet”. be able to.
For example, a plate-shaped molded product having a thickness of 3 mm is produced by hot pressing resin particles, and then a test piece having a length of 5 mm × width of 5 mm × thickness of 3 mm is cut out, and a heat / stress / strain measuring device (SII Nano Using the product name "EXSTRAR TMA / SS6100" manufactured by Technology Co., Ltd., in the needle-insertion test mode (needle tip 1 mmφ), with a load of 500 mN, the needle is applied to the test piece and the temperature is increased at a heating rate of 5 ° C / min. In the TMA curve, the straight line portion that is recognized on the low temperature side from the indenter (needle) starts to penetrate is extended to the high temperature side, and the intersection point of the tangent line where the penetration speed is maximum and the extension line to the low temperature side is the needle. The penetration temperature can be determined as the softening temperature of the resin particles.
When there are two softening temperatures, the temperature of the air passing between the resin particles is preferably at least the softening temperature on the high temperature side, more preferably the softening temperature on the low temperature side or less.

The temperature (T ₀ ) of the air passing between the resin particles can be obtained directly by setting a temperature sensor in the small-diameter region 1a ′ of the chamber 1, but the temperature of the lower space 1b If there is no substantial temperature difference from the temperature of the large-diameter region 1a ″, the temperature of the air passing between the resin particles can be regarded as the same as these temperatures.

The flow rate of air in the chamber can be appropriately selected from flow rates at which the resin particles can flow, and can usually be adjusted depending on the shape, particle diameter, and amount of the resin particles in the container.
The flow rate of air in the chamber for causing the resin particles to flow is usually about 0.1 to 5.0 m / sec.
Although the volatile organic compound can be removed in a shorter time as the flow rate of the air passing through the chamber is increased, the energy required for the operation of the blower 2 becomes excessive and the resin particles become excessive when the flow rate is increased excessively. Alternatively, the resin particles and the inner wall surface of the chamber 1 may collide violently to generate resin powder fine powder.
For this reason, the flow rate of air passing through the chamber is preferably 0.2 to 2.5 m / sec.
The flow rate of this air can be obtained by dividing the flow rate of air in normal pressure passing through the chamber per unit time by the cross-sectional area of the chamber internal space where the resin particles A are accommodated.

In addition, about the quantity of the air which passes the inside of a chamber, optimization can be aimed at by the pressure loss which arises when passing through the area | region in which the resin particle is accommodated.
For example, the differential pressure (pressure loss when passing through the resin particles) between the lower space 1b in the chamber and the upper space 1a above the region where the resin particles are accommodated is in the range of 1 to 500 kPa. It is preferable to adjust, and it is more preferable to adjust so that it may become in the range of 100-400 kPa.

The time for which such a gas is circulated can be appropriately changed depending on the temperature and flow rate of the gas, the removal effect of the volatile organic compound to be obtained, etc., but is usually about several hours.
For example, the time for circulating the gas, that is, the treatment time for removing the volatile organic compound can be appropriately selected from the range of 0.5 to 12 hours.

  Note that the exhaust containing the volatile organic compound is exhausted from the chamber 1 through the exhaust path L3 by performing the treatment for reducing the volatile organic compound on the resin particles containing the polyphenylene ether resin. However, for this exhaust, the volatile organic compound contained can be removed using a separate scrubber or the like.

Thus, the reduction | restoration process of a volatile organic compound is implemented with respect to the resin particle containing polyphenylene ether-type resin, The odor which the said resin particle emits is reduced before the use.
Therefore, the working environment for handling such resin particles can be improved.

In the above embodiment, a case where an upward flow is formed with heated air and a fluidized bed is formed by stirring the resin particles with the upward flow is illustrated, but other than air, for example, nitrogen or the like Even if this gas is used, the same effect as in the above embodiment can be obtained.
In addition, it is not always necessary to stir the resin particles by the upward flow of gas, and a gas higher than the glass transition temperature (T) -70 ° C. passes between the resin particles while stirring the resin particles with a propeller stirring blade or the like. The volatile organic compound contained in the resin particles may be removed from the resin particles.
In that case, the gas flow need not be an upward flow, and may be a downward flow.

  Moreover, in the said embodiment, although the method of the batch type (batch type) is mentioned as a removal method of the volatile organic compound from the resin particle containing a polyphenylene resin, For example, it is used for fractionation of particle size etc. It is possible to adopt a continuous method by adopting equipment such as a trommel type rotary sieve.

  That is, in the trommel type rotary sieve, the horizontally placed cylindrical sieve is rotated, the separated material is introduced from one end side of the sieve, and the separated material is lifted in the rotation direction of the sieve by the rotation of the sieve. Is moved to the other end side while being naturally dropped, and is used for applications such as separation between those that pass through the sieve eyes and those that do not pass during the movement, for example, containing polyphenylene resin The resin particles are continuously supplied to one end side of the trommel type rotary sieve having finer openings than the resin particles, and moved to the other end side while flowing the resin particles by rotation of the trommel type rotary sieve, Reduction of the volatile organic compound relative to the resin particles by removing the volatile organic compound by circulating a gas higher than the glass transition temperature (T) -70 ° C. of the resin particle inside the trommel type rotary sieve. It can be carried out continuously.

Subsequently, the manufacturing method of a polystyrene-type resin foam sheet is demonstrated using the resin particle in which the reduction process of such a volatile organic compound was performed.
In this embodiment, the method conventionally employ | adopted as a manufacturing method of a polystyrene-type resin foam sheet can be employ | adopted except the point which performs the reduction process of a volatile organic compound to a resin particle.
For example, a blended resin pellet made by melting and kneading a polyphenylene ether resin and a polystyrene resin and a polystyrene resin pellet are blended at a predetermined ratio, and a masterbatch containing an air conditioner such as talc is added to this. In addition, if necessary, a deodorant master batch containing a deodorant such as hydrophobic zeolite is added to adjust the composition of the raw materials, and the raw materials are supplied to the extruder and hydrocarbons etc. in the extruder It is possible to employ a method in which the foaming agent is further added and melt-kneaded, and the melt-kneaded kneaded product is ejected from an annular die slit of a circular die provided at the tip of the extruder and extruded and foamed. is there.

  And when blending mixed resin pellets, polystyrene resin pellets, cell conditioner masterbatch, and deodorant masterbatch containing polyphenylene ether resin, these resin particles can be mixed with tumbler mixer or ribbon blender. A step of uniformly mixing with a mixing apparatus will be adopted, but by performing reduction processing of volatile organic compounds by the method for removing volatile organic compounds according to the present embodiment on the mixed resin pellets, Odor generation in such a blending process can be suppressed.

Further, the volatile organic compound may cause another volatile organic compound such as a decomposition product or a reaction product of the volatile organic compound to be formed in a high temperature environment such as an extruder. In the method for producing a polystyrene-based resin foam sheet, since volatile organic compound reduction treatment is performed on the resin particles in advance, generation of odor due to decomposition products of the volatile organic compound during extrusion can be suppressed. The effect which suppresses generation | occurrence | production of the odor from the polystyrene-type resin foam sheet obtained can be anticipated.
That is, in such a method for producing a polystyrene resin foam sheet, the reduction of the volatile organic compound by the method for removing the volatile organic compound as described above is performed on the resin particles containing the polyphenylene ether resin. Thereafter, the resin particles can be extruded and foamed together with other raw materials to provide an improved working environment compared to the conventional method for producing a polystyrene resin foam sheet.

  For such effects, powder resin particles consisting only of polyphenylene ether resin are supplied directly to the extruder by a quantitative feeder or the like separately from other raw materials without previously blending with polystyrene resin pellets. In the case of producing a polystyrene-based resin foam sheet, it can be obtained in the same manner, and such a case is also within the range intended by the present invention.

Next, a method for producing a food container using such a polystyrene resin foam sheet will be described.
In a conventional method for manufacturing a food container, a resin film or the like is laminated on a polystyrene resin foam sheet as necessary, and then thermoforming such as press molding, vacuum molding, pressure molding, vacuum / pressure molding, etc. Is widely adopted.
In this embodiment, a conventional food container, except that a polystyrene-based resin foam sheet prepared by performing a reduction treatment of a volatile organic compound in advance on the resin particles used as described above is used. A method similar to the manufacturing method can be employed.
That is, as a manufacturing method of the food container in the present embodiment, a method of manufacturing the food container by performing the thermoforming on the polystyrene resin foam sheet obtained by the above manufacturing method can be employed.
At this time, the said polystyrene-type resin foam sheet can also implement the said thermoforming only by the said polystyrene-type resin foam sheet, and can also implement the said thermoforming in the state of the laminated foam sheet which laminated | stacked the resin film etc.
In the method for producing a food container of the present embodiment, since the polystyrene resin foam sheet obtained by the above production method is used, the odor emitted from the polystyrene resin foam sheet before thermoforming, and thermoforming The odor generated in the food container can be reduced as well as the reduction of the odor generated in the process.
Note that such effects are not necessarily limited to food containers, but can be expected in general molded products obtained by thermoforming polystyrene resin foam sheets. Since the presence or absence of odor in the container itself is particularly important as compared with the molded product, it can be said that such an effect is exhibited more remarkably.

In particular, a range-up container for cooking cooked food in a microwave oven is required to have excellent heat resistance, but the container itself is also heated in a range-up container containing a volatile organic compound. If so, it may be difficult to add heat resistance by adding a polyphenylene ether-based resin to the raw materials, since odor may be generated during cooking.
On the other hand, it is suitable as a material for forming the above-mentioned range-up container while containing a polyphenylene ether resin by performing a reduction process of the volatile organic compound on the resin particles by the method of removing a volatile organic compound in the present embodiment. A polystyrene-based resin foam sheet can be produced.
That is, by producing a range-up container by thermoforming a polystyrene-based resin foam sheet containing resin particles subjected to a reduction treatment of volatile organic compounds, the generation of odor is suppressed while having excellent heat resistance. Product can be made.

  In addition, this invention is not limited to the aspect illustrated so far, A conventionally well-known event in the removal method of a volatile organic compound, the manufacturing method of a polystyrene-type resin foam sheet, and the manufacturing method of a food container Can be further employed in the specific method illustrated above.

  EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.

(experimental method)
Powdered resin particles consisting only of polyphenylene resin (Sabic, “Noryl PP0646”: glass transition temperature = 210 ° C.), mixed resin of polyphenylene ether resin (PPE) and polystyrene resin (PS) (Savic) In order to remove volatile organic compounds from two types of resin particles, pelletized resin particles made of product name “Noryl EFN4230”, PPE / PS = 70/30: glass transition temperature = 170 ° C. The experiment was conducted using a fluidized bed drying apparatus having the configuration as shown.

(Reduction treatment of volatile organic compounds for powdered resin particles)
The powdered resin particles (“Noryl PP0646”) 4.8 kg was accommodated in a fluidized bed drying apparatus “FBS-0.5 type” manufactured by Okawara Kogyo Co., Ltd.
In addition, the deposition height of the resin particles in the apparatus at this time was 200 mm.
In this state, when the temperature of the resin particles reaches 160 ° C. by circulating air at a temperature of about 200 ° C., the temperature of the air is maintained at 160 ° C., and an upward flow with a wind speed of 0.56 m / s is generated in the apparatus. The resin particles were caused to flow by the upward flow to form a fluidized bed.
In addition, the pressure loss of the fluidized bed at this time was 165 kPa.
The process of allowing the air at 160 ° C. to pass between the resin particles and causing the resin particles to flow with the air was performed for 6 hours.
Then, the resin particles for 1 hour, 3 hours, and 6 hours (at the end of the treatment) after the start of the treatment were extracted as samples for seeing the change with time.

(Reducing treatment of volatile organic compounds for pellet resin particles)
The pelletized resin particles (“Noryl EFN4230”) (6.0 kg) were accommodated in a fluidized bed drying apparatus “FB-0.5 type” manufactured by Okawara Kogyo Co., Ltd.
In addition, the deposition height of the resin particles in the apparatus at this time was 200 mm.
In this state, when the temperature of the resin particles reaches 160 ° C. by circulating air at a temperature of 160 ° C. to 167 ° C., the temperature of the air is maintained at 160 ° C., and an upward flow with a wind speed of 2.3 m / s is generated. Formed in the apparatus, the resin particles were caused to flow by the upward flow to form a fluidized bed.
In addition, the pressure loss of the fluidized bed at this time was 365 kPa.
The process of allowing the air at 160 ° C. to pass between the resin particles and causing the resin particles to flow with the air was performed for 6 hours.
Then, resin particles 3 hours and 6 hours (at the end of the treatment) after the start of the treatment were extracted as a sample for observing a change with time.

(Investigation of content of volatile organic compounds from resin particles)
In order to investigate about the volatile organic compound which may generate | occur | produce a resin particle, the gas chromatograph mass spectrometry by the following head space methods was implemented.

About 0.1 mg of the sample is precisely weighed and sealed in a 20 ml glass vial, dissolved in 1 mL of N, N-dimethylformamide containing diethylbenzene (DEB), heated at 90 ° C. for 1 hour, and sampled from the air layer The content of volatile organic compounds in the sampled gas was investigated.
More specifically, the headspace autosampler “HT200H” manufactured by HTA was set in a gas chromatograph “GC-18A” manufactured by Shimadzu Corporation, and the components in the sampled gas were quantified by an internal standard method (DEB). .
Note that a flame ionization detector (FID) was used as the detector, and the column was “ZB-WAX” (0.25 μm × 0.25 mmφ × 30 m) manufactured by Shimadzu Corporation.
The measurement conditions were as follows.
・ Column temperature:
Hold at 60 ° C. for 3 minutes, heat up to 100 ° C. at 20 ° C./minute, hold at 100 ° C. for 3 minutes, heat up to 40 ° C./minute to 220 ° C., hold at 220 ° C. for 0.5 minutes. Carrier gas: helium ( (Flow rate 1.6mL / min)
・ Inlet temperature: 150 ° C
-Detector temperature: 250 ° C
・ Injection volume: 2mL
-Split ratio: 1/70
・ Gas pressure: 122kPa

(Investigation of the amount of volatile organic compounds generated by thermal decomposition)
In extrusion foaming or the like, a volatile organic compound may be newly formed by thermal decomposition in addition to the volatile organic compound originally contained by heat applied to the resin particles.
Here, the gas chromatograph mass spectrometry by the following purge and trap (P & T) method was implemented, and the volatile organic compound generated when the resin particles were heated at a temperature of 250 ° C. was evaluated.

First, the powdered resin particles were left as they were, and the pelletized resin particles were sliced thinly. Then, about 10 mg of a sample was precisely weighed, wrapped in aluminum foil, and set in a glass-lined stainless steel tube (GLT tube).
In this state, the GLT tube is heated at a temperature of 250 ° C. for 5 minutes, the generated gas is cold trapped in the cryofocus section, and then thermally desorbed to introduce volatile components into the gas chromatograph mass spectrometer (GC / MAS). Measurements were made.
For measurement, GC / MAS (model name “JMS-Q1000GC”) manufactured by JEOL Datum is combined with P & T autosampler (model name “TD-4J”) manufactured by Liquid Chloroscience, and Phenomenex is used. Column (ZB-1 (10 μm × 0.25 mmφ × 60 m)).

The P & T conditions were as follows.
ChargeTime (10s), InjectionTime (20s), DesorbTime (300s), DelayStartTime (10s), Desheater (250 ° C), CryoTemperating (200 ° C), CryoTemp Cooling (-40 ° C)

Furthermore, the measurement conditions were as follows.
・ Column temperature:
Hold at 40 ° C. for 3 minutes, heat up to 200 ° C. at 15 ° C./min, heat up to 250 ° C. at 25 ° C./min, hold for 6.33 minutes at 250 ° C. ・ Carrier gas: helium (flow rate: 1 mL / min)
・ Inlet temperature: 250 ° C
・ Interface temperature: 250 ℃
・ Detector voltage: -1146V
・ Split ratio: 1/10
-Ion source temperature: 250 ° C
・ Ionization current: 300 μA
・ Ionization energy: 70 eV

  The results of the above investigation are shown in Table 1 and Table 2, respectively.

In the above evaluation results, in Table 1, in the case of pellet-like resin particles, toluene, styrene, ethylbenzene, etc. before the reduction treatment of volatile organic compounds (hereinafter also referred to as “initial stage”) as compared with powdered resin particles. A large amount of is observed.
This is based on the point that the pellet resin particles are formed of a mixed resin of a polyphenylene ether resin and a polystyrene resin, whereas the powder resin particles are made of only a polyphenylene ether resin. It is believed that there is.
That is, it is considered that many of the pellet-like resin particles such as toluene, styrene, and ethylbenzene are derived from the polystyrene resin.

  In addition, after the reduction process of a volatile organic compound, compared with the initial stage, these components are reduced significantly, and according to this invention, it turns out that the odor from a resin particle can be suppressed.

Further, when Table 1 and Table 2 are compared, the amount of toluene, styrene, and ethylbenzene generated from the resin particles in the initial stage is much lower in Table 2 than in Table 1.
This is because, in the evaluation shown in Table 2, since heating was performed at a temperature of 250 ° C., these components reacted with other components or decomposed to change their molecular structures. it is conceivable that.
As described above, the amount of toluene, styrene, and ethylbenzene contained in the resin particles is reduced by carrying out the method for removing a volatile organic compound of the present invention.
Therefore, by carrying out the method for removing a volatile organic compound of the present invention, for example, when resin particles are extruded and foamed, toluene, styrene, and ethylbenzene contained in the resin particles are reacted and decomposed. It becomes suppressed that it becomes another odor component.
In fact, in Table 2, it is shown that many components reduce the generation amount by the reduction treatment of the volatile organic compound. According to the present invention, only the generation of odor from the resin particles is shown. It can be seen that the generation of odor when the resin is processed at a high temperature such as during extrusion can be suppressed.
That is, according to the present invention, it can be seen from the above results that the working environment can be improved in the method for producing a polystyrene resin foam sheet.

1: chamber, 2: blower, 3: heat exchanger, A: resin particles, F: airflow

Claims (7)

A method for removing a volatile organic compound that removes a volatile organic compound from a resin particle containing a polyphenylene ether resin,
When the glass transition temperature of the resin particles is T (° C.), the volatile organic compound contained in the resin particles is caused to flow by flowing the resin particles in a gas at a temperature higher than T-70 (° C.). A method for removing a volatile organic compound, wherein the volatile organic compound is removed by being discharged into the gas.   The method for removing a volatile organic compound according to claim 1, wherein the resin particles are resin particles made of only a polyphenylene ether resin.   The method for removing a volatile organic compound according to claim 1, wherein the resin particles are resin particles made of a mixed resin of a polyphenylene ether resin and a polystyrene resin.   The resin particles are accommodated in the container, and an upward flow is formed in the container so that the gas passes from the lower side to the upper side of the resin particles, and the resin particles are caused to flow by the upward flow. The method for removing a volatile organic compound according to any one of claims 1 to 3.   A resin particle containing a polyphenylene ether resin is subjected to a reduction process of a volatile organic compound by the method for removing a volatile organic compound according to any one of claims 1 to 4, and the obtained resin particles A method for producing a polystyrene-based resin foamed sheet, comprising producing a polystyrene-based resin foamed sheet by extruding and foaming a raw material to be contained.   A method for producing a food container, comprising: thermoforming a polystyrene resin foam sheet produced by the method for producing a polystyrene resin foam sheet according to claim 5 to produce a food container.   The method for producing a food container according to claim 6, wherein the food container is a range-up container for cooking the contained food with a microwave oven.

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