JPH07119315B2 - Method for pre-expanding thermoplastic resin particles and apparatus used therefor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for pre-expanding thermoplastic resin particles and an apparatus used therefor. More specifically, thermoplastic resin particles (hereinafter, also referred to as foaming agent-containing particles) containing a volatile foaming agent (hereinafter, also referred to as foaming agent) dispersed in an aqueous liquid under pressure / heating are applied in a low pressure range. The present invention relates to a method for continuously producing pre-expanded particles having a good fusion property while washing the particles to produce pre-expanded particles, and an apparatus used therefor.

[Problems to be Solved by Conventional Techniques and Inventions] Conventionally, by releasing the foaming agent-containing particles under high temperature and high pressure, which are dispersed in an aqueous liquid in a pressure vessel such as an autoclave, into a low pressure region, thermoplasticity is improved. A method of pre-expanding resin particles is known, for example, West German Patent Application Publication No.
No. 2107683, Japanese Patent Publication No. 56-1344, and the like.

However, although the above-mentioned document discloses obtaining a pre-expanded thermoplastic resin, when pre-expanded particles are obtained on an industrial scale, the pre-expanded particles are simultaneously washed to reduce the amount of the dispersant attached. Regarding the reduction, etc., the description is not even suggested, let alone the description, and naturally there is no description about the device used for it.

In addition, JP-A-60-56514 and JP-A-60-105503 describe that the pre-expanded particles are submerged in water to remove the deposits (mainly tricalcium phosphate) on the surface of the pre-expanded particles.

However, this method is effective when the amount of the dispersant used is small, but there is a limit to the reduction of the amount of adhesion in a system having a large amount of the dispersant. If the amount of surface deposits is large, the pre-expanded particles are filled into the mold during molding and the fusion of the pre-expanded particles during steam heating is hindered, resulting in a decrease in the mechanical strength of the molded product. To wake up. When the steam heating time is increased or the steam pressure is increased in order to fuse the pre-expanded particles together, the surface of the molded product is melted and the appearance of the molded product is significantly deteriorated, and the amount of steam used is It will increase and become less economical.

[Means for Solving the Problems] The present invention has been made to solve the above problems, and obtains thermoplastic resin particles containing a volatile foaming agent dispersed in an aqueous liquid and heated under pressure. For pressure resistance, a discharge line in which one end communicates with the lower part of the pressure resistance container and a discharge port is provided at the other end, and a thermoplastic containing a volatile foaming agent in the water dispersion discharged from the discharge port. A low-pressure container sealed with water so that the resin particles are pre-foamed and the volatile foaming agent generated at that time is collected, and the internal space of the low-pressure container is maintained so that the internal pressure of the low-pressure container is maintained at a predetermined pressure. A recovery line for the volatile foaming agent provided in a part of the container, and at least from the outlet to the water-existing portion for sealing in the low-pressure container for cleaning the thermoplastic resin particles released in the low-pressure container. Multiple small hole nozzles provided in part At least from the discharge port to the water-existing portion for sealing in the low-pressure container in order to separate and discharge the sewage produced during cleaning and the thermoplastic resin particles containing the foaming agent to the outside of the low-pressure container. Separation / discharging means provided in part and pre-expanded thermoplastic resin particles are submerged in water in a low-pressure container communicating with the outside, and take-out provided in the low-pressure container to take out through the water to the outside. A thermoplastic resin particle containing a volatile foaming agent, which is dispersed in an aqueous liquid and heated under pressure in a pressure vessel, is sealed with water from one end of the pressure vessel lower portion by using a pre-foaming device including means. The pressure in the space inside the low-pressure container is maintained at a predetermined pressure by discharging the foaming agent into the space inside the low-pressure container to cause pre-foaming and allowing the volatilized foaming agent to flow out from a part of the space inside the low-pressure container. Along with recovering the foaming agent, the discharged thermoplastic resin particles are washed from a plurality of small hole nozzles provided in at least a part from the discharge port in the low-pressure container to the water-existing portion for sealing in the low-pressure container. The presence of sealing water in the low-pressure container from the outlet so as not to mix the cleaning sewage and the aqueous liquid discharged together with the thermoplastic resin particles containing the blowing agent with the water for sealing the low-pressure container. The thermoplastic resin is characterized in that it is separated / discharged by the separation / discharge means provided in at least a part of the section, and the pre-expanded thermoplastic resin particles are submerged by the extracting means, and then taken out through the communicating water to the outside of the low-pressure container. Regarding pre-expansion method of resin particles and pre-expansion device used for the method [Operation] In the present invention, the low-pressure container is sealed with water communicating with the outside and discharged from the discharge port. The thermoplastic resin particles are washed with washing water from a plurality of small-hole nozzles provided in the low-pressure container, the washing wastewater and the aqueous liquid discharged together with the thermoplastic resin particles are separated and discharged, and further manufactured. The pre-expanded particles on the surface of the pre-expanded particles are submerged in water for sealing the low-pressure container by a take-out means such as a rotary impeller attached to the low-pressure container and sequentially taken out to obtain the amount of the deposits on the surface of the pre-foamed particles. The product with a significantly reduced amount is manufactured continuously. In addition, the volatile foaming agent is recovered from the recovery line.

[Examples] In the present invention, generally, the thermoplastic resin particles are first dispersed in an aqueous liquid in a pressure-resistant container, and a volatile foaming agent is added to bring the mixture into a pressurized state, followed by heating. Thermoplastic resin particles containing the agent are prepared.

As the thermoplastic resin forming the thermoplastic resin particles, a foaming agent may be contained, and any thermoplastic resin may be used without particular limitation as long as it is in a viscoelastic state suitable for foaming by heating. . Specific examples of such a thermoplastic resin include polystyrene, high-impact polystyrene, poly-α-methylstyrene,
Styrene-maleic anhydride copolymer, styrene graft polymer of polyphenylene oxide, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene terpolymer, polystyrene polymer such as styrene-butadiene copolymer; low density polyethylene ,
Medium density polyethylene, high density polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer and other polyolefin polymers; vinyl chloride polymers; methyl methacrylate polymers And so on.
These thermoplastic resins may be used alone or in combination of two or more. The polyolefin-based polymer may be used as it is, or may be used after being crosslinked with peroxide or radiation.

The thermoplastic resin can be used as it is, for example, if it is obtained as particles by separating and drying the one obtained by the suspension polymerization method, but a pelletized sheet obtained by an extruder or a calender roll, or In the case of a stick or the like, it is used as a particle after being obtained as a particle by a usual method such as crushing.

The shape of the thermoplastic resin particles used for the production of the foaming agent-containing particles may be any shape such as spherical, elliptical, cylindrical, cubical, rectangular parallelepiped, etc. It is preferable to have a complete set of
The size is preferably 0.5 to 6 mm.

Examples of the foaming agent include hydrocarbons having a boiling point of −50 to 100 ° C. and halogenated hydrocarbons. Specific examples of such a foaming agent include, for example, propane,
Examples thereof include butane, pentane, hexane, heptane, cyclopentane, cyclohexane, monochloromethane, dichloromethane, monochloroethane, trichloromonofluoromethane, dichlorodifluoromethane, dichloromonofluoromethane, trichlorotrifluoroethane, dichlorotetrafluoroethane and the like. These may be used alone or in combination of two or more.

As a use ratio of the thermoplastic resin particles and the foaming agent when the foaming agent is contained in the thermoplastic resin particles, the foaming agent is preferably 2 to 50 parts with respect to 100 parts of the resin particles (parts by weight, the same applies hereinafter). . When the use ratio of the foaming agent is less than 2 parts, the economical meaning of recovering the foaming agent is lost, and when it exceeds 50 parts, the foaming agent is used beyond the limit contained in the thermoplastic resin particles. Only a rise will be wasted.

There are no particular restrictions on the pressure and heating conditions during the production of the foaming agent-containing particles, and they may be appropriately selected depending on the type of thermoplastic resin used, the type of foaming agent, the amount used, and the like.

Dispersion of the thermoplastic resin particles containing a foaming agent in an aqueous liquid (usually water with a dispersant added) is usually carried out in a pressure vessel because the foaming agent-containing particles are produced as described above. Done.

The ratio of the aqueous liquid and the thermoplastic resin particles containing the foaming agent is preferably 15 to 100 parts of the particles to 100 parts of the aqueous liquid. If the proportion of the particles is less than 15 parts, the productivity will decrease and the energy cost will increase. On the other hand, if it exceeds 100 parts, the thermoplastic resin particles are likely to be fused.

The aqueous liquid dispersion obtained as described above is pressurized in a pressure vessel so that the pressure after heating is 5 to 50 kg / cm ² -G, and the mixture is heated with stirring. If the pressure is less than 5 kg / cm ² -G, it takes a long time to discharge, and if it exceeds 50 kg / cm ² -G, the pressure vessel cost becomes high. Although the heating depends on the MI (melt index) of the resin used and the like, it is usually carried out until the temperature of the aqueous dispersion reaches or exceeds the softening point of the resin, and then maintained at that temperature.

Examples of the dispersant used for the preparation of the aqueous liquid include polyvinyl alcohol, methyl cellulose, water-soluble polymers such as polyvinylpyrrolidone, calcium phosphate, magnesium pyrophosphate, inorganic substances hardly soluble in water such as zinc carbonate, or inorganic substances thereof. Examples include a combination of a small amount of anionic surfactant such as sodium dodecylbenzene sulfonate and sodium α-olefin sulfonate.

Then, the aqueous liquid dispersion heated under pressure is discharged from the pressure container through a discharge line having one end communicating with the lower part of the pressure container and a discharge port provided at the other end, for example, an orifice plate, a nozzle. And the like are released into the space inside the low-pressure container sealed with water. At that time, the pressure in the pressure resistant container is maintained by discharging the aqueous liquid dispersion into the low pressure region while introducing nitrogen gas, a foaming agent or the like into the pressure resistant container.

The released blowing agent-containing particles are pre-expanded by volatilization of the blowing agent contained in the particles due to the pressure change.

The expansion ratio is usually about 5 to 50 times.

The foaming agent that volatilizes during foaming is recovered from a recovery line provided in a part of the space inside the low-pressure container, and the internal pressure of the low-pressure container is maintained at a predetermined pressure.

The foaming agent may be recovered, for example, by utilizing the pressure increase generated by the discharge of the aqueous liquid dispersion, or by suction using a means such as a pump. At this time, what is required is to maintain the inside of the low-pressure container at a predetermined pressure, set the expansion ratio of the particles to a predetermined ratio, and collect the volatilized foaming agent from the inside of the low-pressure container.

As a method of maintaining the pressure in the low-pressure container at a predetermined pressure, for example, a container sealed with water is automatically adjusted by using a pressure sensor, a pump, a microcomputer, or the like. A method of providing a valve in the foaming agent recovery line that automatically opens when the pressure exceeds a certain level can be mentioned.

The foaming agent that has flowed out from the low-pressure container for recovery may be used as a raw material for the next foaming after being introduced to a device used for gas purification, separation, and collection and recovered. After liquefying using a compressor, etc.,
May be stored.

The foaming agent-containing particles discharged from the discharge port are foaming or after being foamed, and then the upper part or the side surface of the bonding portion of the low pressure container leading to the water-existing portion for sealing to be submerged in order to take out the pre-expanded particles from the discharge port. The adhering substances on the surface are washed with the washing water ejected from a plurality of small hole nozzles provided in the.

The amount of washing water is preferably about 10 to 50 times the weight of the pre-expanded particles in terms of washing efficiency and cost.

Most of the cleaning wastewater used for cleaning and the aqueous liquid containing the dispersant that is released together with the blowing agent-containing particles are mostly discharged from the discharge port of the low-pressure container up to the water-existing portion for sealing to be submerged in order to remove the pre-expanded particles. It is separated and discharged by the separating / discharging means provided below the binding site. A part of it flows into the water for sealing the low-pressure container together with the pre-expanded particles, but it is preferable to reduce this amount as much as possible in order to remove the deposits adhering to the surface of the pre-expanded particles. When the amount of water that has flowed in is large, for example, when the concentration of the dispersant in the water for sealing is about 100 ppm or more, when the pre-expanded particles are submerged and taken out to the outside, they are washed and the deposits are reduced. It is not preferable because the amount of the reattached substances on the pre-expanded particles increases, and in such a case, when a valve is provided in the lower part of the low pressure container, operation of the valve or water communication with the inside of the low pressure container is performed. It is preferable that the overflow water provided outside the low-pressure container near the water surface is discharged to the outside of the low-pressure container and fresh water is supplied to replace the sealing water.

The pre-expanded particles accumulated in the low-pressure container are submerged by the extracting means provided in the low-pressure container and taken out through the sealing water communicating with the outside.

Next, the first example of the method of the present invention and the apparatus used therefor will be described.
2 to 2 and will be described.

FIG. 1 is an explanatory view of a pre-foaming method using a pre-foaming device whose take-out means is a rotary impeller. In FIG. 1, (1) is a pressure resistant container, which comprises a gas line (4) having a valve for maintaining an internal pressure at a high pressure, foaming agent-containing particles (2) and an aqueous liquid (3). A stirrer (5) for stirring the aqueous liquid dispersion, a heater (6) for heating the aqueous liquid dispersion, and a valve (7) for discharging the aqueous liquid dispersion are provided. In the pressure vessel (1), the foaming agent-containing particles (2) and the aqueous liquid (3) are mixed to prepare an aqueous liquid dispersion, and nitrogen gas or the like is introduced from the gas line (4) as necessary. After being pressurized and pressurized, it is heated under stirring and set to a predetermined pressure and temperature. The aqueous liquid dispersion set to a predetermined pressure and temperature is released from the pressure resistant container (1) through the release line (8) by opening the valve (7).
To the discharge port (9) provided at the other end of the. The discharge port (9) communicates with the low-pressure container (10), and the low-pressure container is sealed with the water existing below it. The water communicates with the inside and outside of the low-pressure container, and a valve (17) is provided so that it can be replaced with fresh water.

The high temperature and high pressure aqueous liquid dispersion introduced to the discharge port (9) is discharged from the discharge port (9) to the space in the low pressure container (10).
From the foaming agent-containing particles (2) in the water dispersion discharged into the low-pressure container (10), the volatile foaming agent contained volatilizes along with the pressure change, and at this time, the volatile foaming agent is heated up to the softening point or higher. The foaming agent-containing particles are foamed. On the other hand, a recovery line (11) is provided so that the volatile foaming agent is recovered and the internal pressure of the low-pressure container (10) is maintained at a predetermined pressure.
In order to maintain the internal pressure of the low-pressure container (10) at a predetermined pressure, as described above, for example, a container sealed with water is automatically adjusted by using a pressure sensor, a pump, a microcomputer, etc. Alternatively, a valve (12) that automatically opens when the pressure in the low-pressure container exceeds a certain pressure may be provided in the foaming agent recovery line.

On the other hand, the volatilized foaming agent is recovered from the recovery line (11), but in this case, it may be absorbed by using a Nash pump, and the foaming agent may be collected in the collector (15) and the low-pressure container. A pressure difference may be generated between the two. The collector (15)
As the collector, any commonly used collector can be used without particular limitation.

The foaming agent-containing particles (2) discharged from the discharge port (9) are pre-foamed and after being pre-foamed, a plurality of small hole nozzles (1) provided at the other end of the washing water line (13).
4) After being washed with water sprayed from it, it falls.

The position where the plurality of small-hole nozzles are present is such that the cleaning wastewater does not flow into the sealing water as much as possible, and the discharge port (9) and the sealing water-existing part are located closest to the discharge port. It is preferable to be located between and. Also, the distance to be washed varies depending on the amount of jet of washing water,
The distance from the discharge port to the separating / discharging means is preferably about the same.

The position where the pre-expanded particles fall is in a low pressure container (1
0) It is preferable from the viewpoint of separation and discharge of the aqueous liquid or the cleaning wastewater that it is the portion where the internal discharge port (9) and the portion where the sealing water is present are connected.

Aqueous liquid (3) released with blowing agent-containing particles (2)
And the cleaning wastewater ejected from a plurality of small hole nozzles (14) provided at the other end of the cleaning water line (13) and used for cleaning is discharged into the discharge port (9) and a portion where sealing water exists. Most of them are separated by the separating / discharging means (16) provided in at least a part of the lower part of the joining portion of the low-pressure container between and are discharged to the outside. In order to prevent the discharged aqueous liquid (3) and cleaning wastewater from flowing into the water for sealing in the separation part (25) of the separation / discharge means (16) of the low-pressure container, for example, a net is used. It is provided so that the pre-expanded particles do not pass through this net or the like and can reach the portion of the container to be submerged in order to take out the pre-expanded particles. The separation part (25) is for preventing washing sewage or an aqueous liquid discharged together with the blowing agent-containing particles from the discharge port from being mixed with sealing water to be submerged for taking out the pre-expanded particles. Therefore, it is preferable to provide as close to the container as possible. Since some cleaning sewage inevitably flows into the sealing water below the low-pressure container, it gradually becomes contaminated. Therefore, it is preferable to replace with fresh water by adjusting the valve (17). At this time, for example, fresh water is supplied by adjusting the valve (17), and the contaminated water is overflowed from the overflow groove (24) provided near the water surface (22) outside the low-pressure container to a suitable height. The liquid level may be adjusted.

On the other hand, the pre-expanded particles are taken out from the low-pressure container (10) while keeping the low-pressure container in a hermetically sealed state and collecting the foaming agent by using an apparatus as described below.

That is, the low-pressure container (10) is sealed and filled with water that communicates with the inside and the outside of the container, so that the pre-expanded particles are submerged and taken out through the communicating water.
A take-out means by a rotary impeller (18) is provided in the low-pressure container.

In order for the low-pressure container (10) to be sealed with water, the partition (1
The water surface (21), (22) must be above the lower end (20) of 9), and the line forming the separating / discharging means (16) is also filled with water up to the rising portion of the curved pipe. There is a need. For the rotary impeller (18), it is preferable to use a plate or a steel plate having a hole through which water can pass but pre-foamed particles cannot pass. The rotary impeller (18) is configured to rotate along a partition wall (19) provided so as to form the circumference of a rotary shaft (23), as shown in FIG. 1, for example. .

Therefore, the rotary impeller (18) has a lower end of the partition wall (19) so that the pre-expanded particles to be submerged by the water are increased as much as possible, and when the sub-expanded pre-expanded particles are taken out of the low pressure container. (20) The distance between the outermost part of the rotary impeller (18) and the lower end (20) of the partition wall (19) is small so that the floating pre-expanded particles are inside the low pressure container of the partition wall so as to float to the outside. The shape is preferably such that it does not float, but the number of blades and the like are not particularly limited. The pre-expanded particles floating on the water surface (21) are submerged in the rotary impeller (18) and passed through the water communicating between the inside and the outside of the low pressure container (10) to the external water surface (22) by the buoyancy of the pre-expanded particles. Surface.

The floated pre-expanded particles naturally overflow, but they can also be taken out by a means such as a suction blower (28).

FIG. 2 is a schematic explanatory view of a pre-foaming method using a pressing plate take-out means.

In this method, the foaming agent-containing particles discharged from the discharge port (9) are pre-foamed and washed in the same manner as in the case of FIG. 1, and the cleaning wastewater and the aqueous liquid are separated and discharged by the separating / discharging means (16). It can be separated and discharged.

In the figure, (27a), (27b), (27c), (27d), (27e)
Shows a state in which the holding plate is lowered by means of a cylinder (26) or the like with the passage of time. The holding plate is made so as to rotate at the lower end of the cylinder, as shown in FIG. 2, about the spindle of the vertically moving cylinder (26). The holding plate descends from the state of (27a), becomes horizontal at the position (27c) where it comes into contact with the pre-expanded particles, and reaches the lower end (20) of the partition wall (19) of the low pressure container (10) sealed with water. After submerged in water, it is rotated from (27d) to (27e), and almost all of the submerged pre-expanded particles are floated on the water surface (22) outside the low pressure container, and can be taken out by means such as a suction blower.

By using the above apparatus, extremely small amount of particles such as a dispersant attached to the surface of the pre-expanded particles can be continuously obtained.

Next, the present invention will be described based on examples, but the present invention is not limited thereto.

Example 1 This example was carried out using the apparatus whose outline is shown in FIG.

300 parts of water (75 parts) in a pressure vessel (internal volume 150) with a stirrer
100 parts (25 kg) of ethylene-propylene random copolymer pellets (density 0.90 g / cm ³ , MI = 9, ethylene content 4.5% (weight%, the same below)) as a dispersant. 15 parts iso-butane (3.75 kg) dispersed with stirring using 3 parts of basic calcium phosphate tribasic and 0.12 parts of sodium n-paraffin sulfonate with stirring
It was pressed into and heated to 133 ° C. At this time, the pressure is 15 kg / cm
It was ^2- G.

After that, the pressure in the container is 20 kg / cm ² -G with iso-butane.
While maintaining the above condition, the aqueous liquid dispersion was discharged into a low pressure vessel sealed with water through a hole having a diameter of 4 mmφ opened in an orifice plate to foam pellets to obtain pre-expanded particles. At that time, since the internal pressure of the low-pressure container rises due to iso-butane volatilized from the pellets, the foaming agent generated by opening the valve of the recovery line was allowed to flow out of the recovery line, and the internal pressure of the low-pressure container was maintained at about atmospheric pressure. .

The foaming agent that flowed out was collected in a bowl-type collector.

On the other hand, the discharged particles are 40% of the weight of the resin ejected from a plurality of small hole nozzles provided at the end of the washing water line.
Washed with double wash water. The generated cleaning wastewater was separated and discharged from the separating and discharging means together with the discharged aqueous liquid.

The pre-expanded particles dropped on the water for sealing in the low-pressure container were submerged by a rotary impeller and taken out to the outside.

The amount of deposits (mainly tricalcium phosphate) on the surface of the obtained pre-expanded particles was 900 ppm. When a molded body was molded using the pre-expanded particles, the fusion rate was 90.
%, A good molded product was obtained. It should be noted that the fusion rate is the total number of spare parts of the fractured surface of the molded product, which is the number of fractured parts inside the pre-expanded particles appearing on the fracture surface when the molded product is broken (not the number of fractures at the interface of the pre-expanded particles). The ratio (%) to the number of expanded particles.

Example 2 Pre-expanded particles were obtained in the same manner as in Example 1 except that the pre-expanded particles in the low-pressure container were taken out by the holding plate take-out means.

The amount of deposits (primarily calcium tertiary phosphate) on the surface of the obtained pre-expanded particles was 1000 ppm.

When a molded product was molded using the pre-expanded particles, a good molded product with a fusion rate of 80% was obtained.

Comparative Example 1 The sewage water from which the pre-expanded particles were washed and the discharged aqueous liquid were allowed to flow directly to the sealing water below the low-pressure container without being separated / discharged by the separation / discharge means, and the pre-expanded particles were taken out by the rotary impeller. Pre-expanded particles were obtained in the same manner as in Example 1 except for the above. The amount of deposits (mainly tricalcium phosphate) on the surface of the obtained pre-expanded particles was 3300 ppm, and a pre-formed particle was formed using this pre-expanded particle. I couldn't get it.

Comparative Example 2 The sewage water from which the pre-expanded particles were washed and the discharged aqueous liquid were allowed to flow directly to the sealing water below the low-pressure container without being separated / discharged from the separating / discharging means, and the pre-expanded particles were taken out by the holding plate take-out means. Pre-expanded particles were obtained in the same manner as in Example 2 except for the above. The amount of deposits (mainly tricalcium phosphate) on the surface of the obtained pre-expanded particles was 3700 ppm. A molded body was molded using the pre-expanded particles,
No satisfactory molded product was obtained at a fusion rate of 0%.

[Effects of the Invention] In the present invention, the low-pressure container is sealed with water communicating with the outside, and while the foaming agent-containing particles discharged from the pressure-resistant container are pre-expanded, or after the pre-expansion, a plurality of particles are provided in the low-pressure container. Washing with washing water from the small-hole nozzle, separating and discharging the washing wastewater and the aqueous liquid discharged together with the foaming agent-containing particles, and further submerging them by using the take-out means attached to the low-pressure container, and sequentially to the outside. By taking out
The amount of deposits on the surface of the pre-expanded particles can be remarkably reduced while continuously and while collecting the blowing agent, and pre-expanded particles with improved fusion properties can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view of an example of the pre-foaming device of the present invention in which the take-out means is a rotary impeller, and FIG. 2 is an explanation of an example of the pre-foaming device of the present invention in which the take-out means is a holding plate take-out means. It is a figure. (Main symbols in the drawing) (1): Pressure resistant container (2): Foaming agent-containing particles (3): Aqueous liquid (8): Release line (9): Release port (10): Low pressure container (11): Recovery line (14): Small hole nozzle (16): Separation / discharge means

Claims (6)

[Claims] 1. A pressure-resistant container for obtaining thermoplastic resin particles containing a volatile foaming agent dispersed in an aqueous liquid and heated under pressure, one end of which communicates with a lower portion of the pressure-resistant container and the other end of which is released. A discharge line provided with an outlet, the thermoplastic resin particles containing the volatile foaming agent in the water dispersion discharged from the outlet are pre-foamed, and the volatile foaming agent generated at that time is recovered As described above, a low-pressure container sealed with water, a volatile foaming agent recovery line provided in a part of the internal space of the low-pressure container so that the internal pressure of the low-pressure container is maintained at a predetermined pressure, and the inside of the low-pressure container In order to wash the thermoplastic resin particles discharged to the, a plurality of small hole nozzles provided in at least a part from the discharge port to the water-existing portion for sealing in the low-pressure container, sewage produced during cleaning, and Release with thermoplastic resin particles containing blowing agent In order to separate and discharge the aqueous liquid to the outside of the low-pressure container, a separating / discharging means and a pre-foamed thermoplastic resin provided in at least a part from the discharge port to the water-existing portion for sealing in the low-pressure container. Particles are submerged in water in a low-pressure container communicating with the outside, and dispersed in an aqueous liquid in a pressure-resistant container by using a pre-foaming device consisting of a take-out means provided in the low-pressure container to take out through the water to the outside. The thermoplastic resin particles containing a volatile foaming agent that are heated under pressure are discharged from one end of the lower part of the pressure-resistant container into the space inside the low-pressure container that is sealed with water for pre-foaming, and the foam that volatilizes at that time. By allowing the agent to flow out from a part of the low-pressure container internal space, the pressure of the low-pressure container internal space is maintained at a predetermined pressure to recover the foaming agent, and the released thermoplastic resin particles are discharged into the low-pressure container. Wash with wash water from a plurality of small hole nozzles provided at least in part from the discharge port to the water-existing part for sealing in the low-pressure container, and discharge with the wash wastewater and thermoplastic resin particles containing a foaming agent. The aqueous liquid to be separated and discharged by the separation and discharge means provided at least in part from the discharge port to the water-existing portion for sealing in the low-pressure container so as not to mix with the water for sealing the low-pressure container, A method for pre-expanding thermoplastic resin particles, characterized in that the pre-expanded thermoplastic resin particles are submerged by an extracting means and taken out through a communicating water to the outside of the low-pressure container. 2. The pre-foaming method according to claim 1, wherein the take-out means is a rotary impeller provided in a low-pressure container for submerging the pre-foamed particles in water and taking them out through the communicating water. 3. The holding plate taking-out means provided so as to go up and down along the partition wall in the low-pressure container in order to submerge the pre-expanded particles in water and take them out through the communicating water to the outside. Pre-foaming method. 4. A pressure vessel for obtaining thermoplastic resin particles containing a volatile foaming agent dispersed in an aqueous liquid and heated under pressure, one end of which communicates with a lower portion of the pressure vessel and the other end of which is released. A discharge line provided with an outlet, the thermoplastic resin particles containing the volatile foaming agent in the water dispersion discharged from the outlet are pre-foamed, and the volatile foaming agent generated at that time is recovered As described above, a low-pressure container sealed with water, a volatile foaming agent recovery line provided in a part of the internal space of the low-pressure container so that the internal pressure of the low-pressure container is maintained at a predetermined pressure, and the inside of the low-pressure container In order to wash the thermoplastic resin particles discharged to the, a plurality of small hole noise provided in at least a part from the discharge port to the water-existing portion for sealing in the low-pressure container, sewage generated during cleaning, and Release with thermoplastic resin particles containing blowing agent In order to separate and discharge the aqueous liquid to the outside of the low-pressure container, a separating / discharging means and a pre-foamed thermoplastic resin provided in at least a part from the discharge port to the water-existing portion for sealing in the low-pressure container. A pre-foaming device comprising a take-out means provided in a low-pressure container for submerging particles in water in a low-pressure container communicating with the outside and taking the water through the water to the outside. 5. The pre-foaming device according to claim 4, wherein said take-out means is a rotary impeller provided in a low-pressure container for submerging the pre-foamed particles in water and taking out the communicating water to the outside. 6. The holding plate take-out means provided so as to go up and down along a partition wall in the low-pressure container for submerging the pre-expanded particles and taking them out through the communicating water to the outside. Pre-foaming device.