JPH0488036A - Production of molded article of expanded polystyrene and production device therefor - Google Patents

Abstract

PURPOSE:To obtain the title molded article having a few pinholes in a shortened molding time by transferring pre-expanded polystyrene particles in an aging hopper to a service hopper, blowing hot air upon the particles, retaining, packing into a molding machine, expanding by heating and molding. CONSTITUTION:Steam is supplied to a pre-expanding machine 1 charged with expandable polystyrene particles containing a blowing agent, the particles are expanded to give pre-expanded particles, which are then sent through a transfer pipe 3 to an aging hopper 4 by air pressure fed from a blower 2. The blowing agent in the pre-expanded particles in the aging hopper 4 is replaced with air, the particles are aged, a given amount of the particles is transferred to a service hopper 7 by a blower 5, hot air is blown from a hot air feeder 9 on the pre- expanded particles in the hopper 7, the particles are retained, then the pre- expanded particles in the service hopper 7 are packed into a molding chamber 17 of a molding machine and expanded under heating to give the objective expanded molded article.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for producing a foamed polystyrene molded article.

[Conventional technology and Problems that the invention attempts to solve]

Conventionally, as a method for manufacturing expanded polystyrene molded bodies,
The pre-expanded particles obtained by steam-heating and foaming expandable polystyrene particles containing a blowing agent in a pre-expanding machine are held in an aging popper for a predetermined period of time, and are then molded in a predetermined amount (usually 2 to 3 times) from an aging popper. The amount required for one molding is transferred to the service hopper, and the amount required for one molding is filled from the service hopper into the molding chamber of the molding machine, and the pre-expanded particles in the molding chamber are heated with steam etc. to foam and melt. This method of dressing is widely used. However, when producing pre-expanded particles, steam is usually supplied directly to the expandable polystyrene particles to cause foaming, so a large amount of water droplets adhere to the surface of the resulting pre-expanded particles. When pre-expanded particles are filled into a molding chamber and molded, there are problems such as pinholes being formed in areas where water droplets have adhered, and particles not adhering to each other. When trying to obtain a molded body, problems such as the need for a large amount of heating steam during molding occurred.

For this reason, it is necessary to dry the pre-expanded particles to be filled into the molding chamber as much as possible. Particularly in recent years, particles with a small particle size are preferred as pre-expanded particles for molding due to their appearance, but the smaller the particle size, the higher the incidence of pinholes etc. and poor fusion. There is a problem.

For this reason, conventionally, when the pre-expanded particles obtained by supplying steam to the expandable polystyrene particles in a pre-expanding machine to heat and foam them are transferred to a ripening popper, a method has also been adopted in which the particles are transferred while blowing hot air. However, with this method, it is difficult to completely remove water droplets adhering to the pre-expanded particles, especially when an antistatic agent is added or when condensate tends to accumulate, such as in the winter. There is a problem in that the rate of occurrence of pinholes and poor fusion increases due to the increased adhesion of water droplets to the surface.

The present invention has been developed in view of the above points, and it is possible to reduce the amount of water adhering to the surface of pre-expanded particles, and it is possible to obtain a molded product without pinholes or poor fusion. It is an object of the present invention to provide a method and apparatus for manufacturing a foamed polystyrene molded body that can reduce the amount of steam required and shorten the molding cycle.

[Means to solve the problem]

That is, in the method for producing a foamed polystyrene molded article of the present invention, a predetermined amount of polystyrene pre-expanded particles in an aged popper is transferred to a service hopper, the pre-expanded particles are held in the popper by being blown with warm air, and then the pre-expanded particles are held in the popper. The method is characterized in that the pre-expanded particles in the service hopper are filled into the molding chamber of the molding machine and heated and foamed. The molding apparatus of the present invention also includes a service hopper which has a warm air blowing hole inside and holds a predetermined amount of polystyrene pre-expanded particles transferred from the aging popper while blowing hot air thereinto, and It consists of a molding machine having a molding chamber for heating and foaming supplied pre-expanded particles to mold them.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 1, reference numeral 1 denotes a pre-foaming machine. In the pre-foaming machine 1, pre-foamed particles are produced by supplying steam to expandable polystyrene particles containing a blowing agent to cause them to foam. Usually, expandable particles contain 6 to 8% by weight of a blowing agent such as butane, propane, pentane, etc., and foaming behavior changes depending on the type of blowing agent. It foams depending on the conditions.

The pre-expanded particles produced in the "pre-expander" are transferred to the ripening hopper 4 through the transfer pipe 3 by the pressure of air supplied from the blower 7-2. Air at room temperature may be supplied from the blower 2, but warm air may also be supplied to accelerate drying of the pre-expanded particles.

y) The foaming agent in the pre-expanded particles is replaced with air in the forming hopper 4, and as the replacement of the foaming agent with air progresses, the compression modulus of the particles increases. Aging in the aging hopper 4 is performed until the recovery rate reaches 60 to 75% when the particles are compressed to 60%. At this time, if there is a large amount of moisture adhering to the particles or if the aging hopper 4 has a large capacity, stirring tends to be poor and the aging time tends to be long. For this reason, as the ripening hopper 4, a cloth popper or the like with a large porosity is often used.

Next, a predetermined amount of the pre-expanded particles (N usually used for 2 to 3 moldings) in the aging hopper 4 is passed through a transport vibro by air supplied from the blower 7-5 or by suction. and transferred to the service hopper 7. For example, as shown in FIG. 1, the service hopper 7 has a bottom plate 8 made of wire mesh, punched metal, etc. near the bottom, and the hot air supplied into the service hopper 7 from the hot air supply device 9 through the blowing port 10 is After heating the pre-foamed particles that are introduced into the particle storage space 11 in the hopper 7 through the hole in the bottom plate 8 and held there, a large number of particles made of wire mesh, punched metal, etc. provided on the ceiling of the hopper 7 are heated. It is configured to be discharged to the outside of the hopper 7 through a through hole in a ceiling plate 12 having a through hole. 13 is a hot air diffusion plate provided to uniformly supply hot air.

The temperature of the hot air supplied into the service hopper 7 is usually 3
The temperature is 6-80°C. Also, the retention time of the pre-expanded particles in the service hopper 7 (heating retention time with warm air)
is 5 to 30 minutes. The pre-expanded particles held in the service hopper 7 while blowing hot air are sent by air from a blower or compressor 14 to a filling machine 15 of a molding machine consisting of a filling m15 and a mold 16, and the filling machine 15 After being filled into the molding chamber 17 of the mold 16, it is heated by steam and molded.

While the pre-expanded particles filled in the molding chamber 17 as described above are being molded, the amount corresponding to the pre-expanded particles that has decreased in the service holster 7 is transferred from the maturing holster 4 and replenished; In the same manner as above, the blowing of hot air is kept downward.

In the above example, the service hopper 7 is configured such that the hot air supplied into the service hopper 7 from the blowing port 10 is supplied to the pre-expanded particles through the hole in the bottom plate 8. It can have any shape and structure as long as it can blow warm air onto the pre-expanded particles in the hopper 7.

Hereinafter, the present invention will be explained in more detail by giving specific examples.

Example 1 Pre-expanded particles obtained by heating and foaming polystyrene particles (average particle size 1.0 mm) containing 6% by weight of n-pentane as a blowing agent with steam were held in an aging homper for 4 hours and then aged. , pre-expanded particles in the aging hopper 0.
After transferring 35 rd to a service hopper and supplying 50°C warm air into the service hopper for 10 minutes,
It was filled and molded into a mold having a molding chamber of 0x300x50 mm. The moisture content of the molded product was reduced from 5% to 3% compared to a molded product obtained using pre-expanded particles held in a service hopper without blowing hot air. Furthermore, the molding cycle could be shortened from 120 seconds to 100 seconds.

Furthermore, the aging time in the aging hopper could be shortened by 1.5 hours.

Example 2 Pre-expanded particles similar to those in Example 1 were blown with warm air at 40°C in a service hopper and held for 10 minutes.
It was filled into a molding chamber measuring 0 x 425 x 1820 mm and molded. The moisture content of the obtained molded product was reduced from 4% to 2.5% compared to one that was not blown with hot air, and a good molded product could be obtained even if the amount of steam required for molding was reduced by 15%. was completed. In addition, the obtained molded product showed a 10% improvement in the shredding speed during hot wire cutting, had a beautiful appearance, and had few pinholes inside.

〔Effect of the invention〕

According to the method of the present invention, it is possible to reduce the amount of water adhering to the pre-expanded particles supplied to the mold, thereby making it possible to obtain a molded body with few pinholes and good mutual fusion of particles, and the amount of steam required for molding. It can also contribute to reducing the amount of water and shortening the molding cycle. Moreover, even if the aging time is shortened, a good molded product can be obtained.

Furthermore, the apparatus of the present invention has the advantage that the method of the present invention can be carried out reliably.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic cutaway view of essential parts of an apparatus related to carrying out the method of the present invention. 4...Aging hopper 7...Service hopper-8.
...Bottom plate 10...Blowing port 15...Filling machine 1
6...Molding mold 17...Molding chamber 7...Service hopper 8...Bottom plate 15...Filling machine 16...Molding mold 17...Molding chamber

Claims (2)

[Claims] (1) Transfer a predetermined amount of polystyrene pre-expanded particles in the aging hopper to a service hopper, blow warm air onto the pre-expanded particles in the hopper to hold them, and then transfer the pre-expanded particles in the service hopper to a molding machine. 1. A method for producing a foamed polystyrene molded article, which comprises filling a molding chamber with the foamed polystyrene and heating and foaming it. (2) a service hopper having a hot air blowing hole inside and holding a predetermined amount of polystyrene pre-expanded particles transferred from the aging hopper while blowing warm air;
1. An expanded polystyrene molded product manufacturing apparatus comprising a molding machine having a molding chamber for heating and foaming pre-expanded particles supplied from the service hopper.