JPH06155605A - Manufacture of thermoplastic form board having internal void - Google Patents

Abstract

PURPOSE:To make it possible to prevent wooden house from sweating by enhancing the water vapor permeability of the board concerned by a method wherein voids are produced among beads by filling and thermoforming the mixture of two or more of foaming beads, the prefoamed beads of which are different from each other in a mold. CONSTITUTION:When deformed foams 2 different in bead form from each other are mixed and formed, the fused portion is locally bonded one, resulting in leaving much voids 4. And, even when blowing gas dissipating spherical foams, the gas percentages of which are adjusted, are mixed, much voids 4 are produced, since only blowing gas holding beads expand. However, since poor fusion tends to occur among the above-mentioned beads, mixture must be prepared under the condition that foaming beads having the gas percentage of 2% or less are expanded up to the comparatively larger size of abut 5-8mm and prefoaming beads having the gas percentage of 3% or more are expanded up to the size of about 3-5mm. By producing thermoplastic resin having much voids therein as mentioned above, the water vapor on the indoor side can be discharged on the open air side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thermoplastic foamed resin plate having internal voids, and more particularly to a moisture permeable heat insulating building material such as a wooden base material or a civil engineering member requiring water permeability. The present invention relates to a method for producing a thermoplastic foamed resin plate suitable for use in.

[0002]

2. Description of the Related Art Conventionally, a thermoplastic foamed resin plate having a good heat insulating property has been used as a base material outside a fibrous heat insulating material such as glass wool as a heat insulating base building material for a wooden house. This thermoplastic foamed resin plate has a poor water vapor permeability, causing dew condensation in the fibrous heat insulating material portion and causing wood and the like to be damaged. In order to prevent this, a moisture-proof sheet such as a polyethylene sheet is put on the indoor side to make the inside airtight, but it is difficult to stretch the sheet seamlessly and it is impossible to prevent dew condensation. Is.

Such thermoplastic foam resin plates are roughly classified and are manufactured by the following two methods. A method called extrusion foaming method in which a thermoplastic resin melted under high pressure is mixed with a compressible liquefied gas such as methyl chloride or hydrocarbon and extruded under normal pressure from an extruder die to form a plate, A beaded or pelletized raw material in which a foaming gas is injected by a suspension polymerization method or an impregnation method of a thermoplastic resin called an internal foaming method (bead foaming method) is steam-foamed by a prefoaming machine into prefoamed particles having a predetermined bulk density. Then, after aging and curing, it is filled in the mold cavity, and then steam is blown to make the pre-expanded particles in a softened state, and the pre-expanded particles are fusion-molded by the secondary expansion expansion pressure, and then cooled.・
There is a method of taking out the product through cooling.

[0004]

The problems described in the prior art have the following problems. Thermoplastic foam resin plate molded by conventional in-mold foaming method,
It is required to have good heat insulation performance, high moisture vapor resistance (small water vapor permeability), high compressive strength, and low water absorption. In order to satisfy these requirements, grades, types of foaming agents, additives, bead diameters, cell structures, etc. have been studied in raw materials. Also, in the manufacturing method, expansion ratio, aging time, structure of molding machine, molding conditions, etc. have been studied,
Often set empirically.

An object of the present invention is to produce a thermoplastic foamed resin plate having a predetermined water vapor permeability by focusing on the voids between the thermoplastic foamed particles and adjusting the void ratio. Further, in order to produce a product with many voids by the conventional molding method, it is necessary to suppress the secondary foaming pressure at the time of mold molding, and it is possible to reduce the heating pressure or shorten the heating time. It's worn badly and tattered.

The present application has been made in view of the above problems of the prior art, and an object of the present application is to provide the following things. The present invention is an in-mold foam molding method for producing a thermoplastic foam resin plate having many voids to improve water vapor permeability and prevent dew condensation in a wooden house.

[0007]

In order to achieve the above object, the present invention is as follows. The present invention is
Two or more types of expanded particles having different pre-expanded particles are mixed, filled in a mold, and heat-molded to form voids between the particles to adjust the water vapor permeability.

More specifically, a method of using raw materials having different particle diameters or shapes of raw material particles or different kinds of volatile gas and mixing pre-expanded pre-expanded particles separately, different pre-expanded bulk densities (expansion ratio of the same raw material) ) And mixing these pre-expanded particles, pre-expanded with the same raw material, and pre-expanded particles with one pre-expanded particle having a gas ratio of 2% or less and a gas ratio of 3% or more There is a method of mixing particles, a method of pre-foaming different pre-expanded bulk densities of different raw materials, and adjusting the gas ratio of one pre-expanded particle to 2% or less and mixing the pre-expanded particles.

The size of the pre-expanded particles must be determined in consideration of the porosity and the apparent density. Further, the gas ratio can be adjusted in a short time by raising the temperature of the curing chamber, since the secondary foaming hardly occurs if it is 2% or less in the aging curing stage after the pre-foaming. The mixing ratio of the pre-expanded particles is particularly closely related to the porosity, but if the amount of the pre-expanded particles having a gas ratio of 2% or less is 50% or less in terms of the total volume%, defective fusion occurs. Also, the molding conditions are usually 0.2 to 0.5 k from the heating pressure.
The higher the g / cm ² , the better the fusion.

The block manufactured in this manner was cut into slices and the cut edges were viewed as shown in the following figure. FIG. 1 shows the case where a spherical bead raw material is used, FIG. 2 shows the case where odd-shaped particles are mixed and molded, and FIG. 3 shows the case where the gas ratio of pre-expanded particles is adjusted with the spherical bead raw material. When the mold is densely packed with uniform spherical bodies, the void volume is 40% of the total volume, and normal conditions (heating pressure 0.5-1.0 kg / cm
² , the cut surface of the spherical foam 1 molded with a heating time of 60 to 90 seconds has a structure of 6 to 8 tetrahedra, and the particles are strongly fused into a planar body.

The irregularly shaped foam 2 having different grain shapes as in the present invention
When mixed and molded, the fusion-bonded portion is partially adhered and the voids 4 increase. Also, when the foaming gas diffusion spherical foam 3 having the adjusted gas ratio is mixed, only the particles having the foaming gas expand, so that the voids 4 can be similarly increased. However, since the fusion tends to be insufficient, expanded particles with a gas ratio of 2% or less are expanded into a relatively large shape of 5 to 8 mm, and pre-expanded particles with a gas ratio of 3% or more are expanded to about 3 to 5 mm and mixed. Must.

The thermoplastic foaming raw material used in the present invention is a thermoplastic resin such as polystyrene resin, polyethylene resin or polymethylmethane acrylate resin mixed with a foaming agent of volatile liquid such as propane, butane, pentane or methyl chloride. It is a thing. Polystyrene resin is the most excellent in improving the water vapor permeability, and is most effective in the present invention because it has a transmittance of 1000 times that of air. Although the mechanism of foam fusion is complicated and has not been clarified, it is considered that water vapor easily enters the air bubbles through the cell membrane and produces a foaming effect by the partial pressure of water vapor. Further, the expanded beads are softened by being heated above the glass transition point, go through a rubber-like state and become a fluidized state to be fused. It was found that the polystyrene foam plate manufactured in this manner has a moisture vapor transmission resistance of 3 to 10 m ² hmmHg / g, which is 10 times or more the water vapor permeability of conventional products.

[0013]

【Example】

(Example 1) Oval pellets having a gas ratio of 6%, a diameter of 2 mm and a length of 5 mm and spherical beads having a gas ratio of 6% and a diameter of 2 mm were pre-expanded 30 times, and then aged for 24 hours. Next, the pre-expanded particles were mixed in a volume ratio of 50:50 and filled in a block mold molding machine. After preheating, the heating pressure is 0.5 kg / cm ² , the heating time is 70 seconds, and the length is 1820 mm and the width is 920 mm under the conditions of cooling for 40 minutes.
A block foam molding having a thickness of 425 mm was manufactured. This block was cut into slices having a thickness of 25 mm, and the physical properties were measured. As a result, the density was 30 kg / m ³ , the compressive strength was 2.4 kg / cm ² , and the thermal conductivity was 0.034 Kcal / m.
The fusion was also good at h ° C. and moisture permeability resistance of 3.5 m ² hmmHg / g.

(Example 2) Pre-expanded particles having a diameter of 2 mm and a diameter of 2 mm were pre-expanded 60 times, and then pre-expanded particles having a diameter of 5 mm were aged and cured in a drying chamber until the volatile content was reduced to 2% or less. After pre-foaming 25 times with the same raw material,
Pre-expanded particles having a diameter of 3 mm and aged for 24 hours and 30:
The mixture was mixed at a volume ratio of 70 and filled in a block mold molding machine. After preheating, heating pressure 0.7kg / c
m ^2, the heating time of 70 seconds, the length under the conditions of cooling 30 minutes of 18
A block foam molding having a size of 20 mm, a width of 920 mm and a thickness of 425 mm was manufactured. This block was cut into slices having a thickness of 25 mm, and the physical properties were measured. Product physical density is 3
2 kg / m ³ , compressive strength 2.5 kg / cm ² , thermal conductivity 0.031 Kcal / mh ° C., moisture permeability resistance 4.0 m ² hm
The fusion was also good at mHg / g.

The operation will be described together with the effect.

[0016]

Since the present invention is configured as described above, it has the following effects. As is clear from the above description, by manufacturing the thermoplastic foamed resin plate having many voids, it is possible to release the water vapor inside the room to the outside air without deteriorating the heat insulation performance of the wooden house. Further, since the water permeability is improved, it can be applied to civil engineering members that require drainage.

[Brief description of drawings]

FIG. 1 is a cut sectional view of a foam obtained by a conventional molding method using spherical pre-expanded particles.

FIG. 2 is a cut sectional view of a foam molded by mixing two types of pre-expanded particles using a deformed raw material.

FIG. 3 is a cross-sectional cutaway view of a foam formed by mixing spherical pre-expanded particles of the pre-expanded particles diffused with foaming gas and conventional pre-expanded particles aged and cured.

[Explanation of symbols]

 1 Spherical foam 2 Deformed foam 3 Foam gas diffusion Spherical foam 4 Void

Claims (5)

[Claims] 1. An in-mold foaming method, wherein two or more different types of pre-foamed particles are mixed and filled before molding with a mold to form voids between the particles to adjust water vapor permeability. A method for producing a thermoplastic foamed resin plate having internal voids, comprising: 2. The thermoplastic foamed resin plate with internal voids according to claim 1, wherein raw materials having different particle diameters or shapes of raw material particles or kinds of volatile gas are used, and the prefoamed particles which are prefoamed separately are mixed. Manufacturing method. 3. The method for producing a thermoplastic foamed resin plate having internal voids according to claim 1, wherein the same raw material is prefoamed to have different prefoaming bulk densities and these prefoamed particles are mixed. 4. The internal voids according to claim 1, wherein the pre-expanded particles obtained by pre-expanding the same raw material and adjusting the gas ratio of one of the pre-expanded particles to 2% or less and the pre-expanded particles having a gas ratio of 3% or more. A method for producing a thermoplastic resin foam plate. 5. The pre-expanded particles are mixed by pre-foaming different pre-expanded bulk densities of different raw materials and adjusting the gas ratio of one pre-expanded particle to 2% or less.
A method for producing a thermoplastic foamed resin plate having internal voids as described above.