JPH11240062A - Production equipment of foam thermoplastic resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a miniaturized production equipment by a method wherein at least a part of a wall part surrounding a vacuum chamber is made of a member having a plurality of vacuum vents so as to execute evacuation through this member. SOLUTION: The inner wall parts 14 of a movable upper wall part 12 and of a movable lower wall part 13 are made of members having evacuation vents such as porous electroformed shells. When a foaming agent and a thermoplastic resin are melted and kneaded in an extruder 1 and extruded through a die 3 in the form of a sheet-like expandable thermoplastic resinous body 6a, the distance between the wall surface 12a of the movable upper wall part 12 and the wall surface 13a of the movable lower wall part 13 is made narrower when the evacuation of a vacuum chamber is not yet started, and consequently the thickness of the resinous body 6a is thin, while the distance is made broader when its thickness becomes thick after the start of evacuation of the chamber and the expansion of the resinous body, resulting in preventing the situations such as the scratching of the surface of a sheet 6 and the crushing of bubbles from occurring. The edge parts of sealing materials 31 reach the surfaces of the resinous body 6a so as to cover the outlet of the vacuum chamber, resulting in evacuating the vacuum chamber 4 for expanding the resinous body and making the distance between the wall surfaces 12a and 13a broader until the desired thickness W2 of the resinous body is obtained. By passing through an expanding zone 7, the resinous body 6a expands more so as to obtain a foam thermoplastic resin sheet 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing a foamed thermoplastic resin sheet which performs foam molding under reduced pressure.

[0002]

2. Description of the Related Art As a conventional method for producing a foamed thermoplastic resin sheet (hereinafter, sometimes simply referred to as a sheet), a thermoplastic resin and a foaming agent are melted and kneaded by an extruder, and then a die is used. Methods of extruding into atmospheric pressure are known. However, in order to obtain a highly foamed sheet by this production method, a large amount of a foaming agent is required, and there is a problem that the foam becomes coarser as the foaming becomes higher, and the strength of the sheet decreases accordingly. Was.

In order to solve such a problem, the expandable thermoplastic resin body which has exited the extruder is passed through a decompression device, so that the expandable thermoplastic resin body is further foamed and highly foamed. A method has been implemented.

For example, Japanese Patent Publication No. 58-29328 (Patent No. 1199174) and Japanese Patent Publication No. 2-54215 (Patent No. 1639854) disclose a suction port provided in a partition wall constituting a decompression chamber. A configuration is described in which the port is connected to a vacuum pump and vacuum is drawn.

[0005] In the present specification, the thermoplastic resin in the primary foaming stage, which is further foamed under reduced pressure, is defined as "foamable thermoplastic resin", and this foamable thermoplastic resin is further foamed under reduced pressure. The final foamed state after and immediately before the solidification is defined as a “foamed thermoplastic resin”. Also,
The thermoplastic resin foamed under reduced pressure is included in the former “foamable thermoplastic resin”.

[0006]

However, in a configuration in which a suction port is provided in a partition wall and the suction port is connected to a vacuum pump to evacuate the vacuum, as in the above-described conventional manufacturing apparatus,
Even if the foamable thermoplastic resin foams, a large decompression chamber that does not contact the wall surface is required. This is because a desired degree of vacuum cannot be obtained if the expandable thermoplastic resin foams largely due to the reduced pressure and comes into contact with the inner wall to close the suction port provided in the inner wall.

Accordingly, the conventional apparatus for manufacturing a foamed thermoplastic resin sheet has a problem in that the size cannot be reduced.

[0008] Further, in a configuration in which the foamed thermoplastic resin body is not brought into contact with the wall surface, the cooling efficiency when cooling the foamed thermoplastic resin body is low, and it is necessary to take a long section for cooling in order to ensure cooling. Had to be enlarged.

An apparatus for producing a foamed thermoplastic resin sheet of the present invention has been made in view of the above problems, and an object thereof is to provide an apparatus for producing a foamed thermoplastic resin sheet which can be reduced in size.

[0010]

The apparatus for producing a foamed thermoplastic resin sheet of the present invention has the following objects.
An extruder for melting and kneading a thermoplastic resin and a foaming agent; a die provided at the extruder tip for processing a foamable thermoplastic resin body melted and kneaded by the extruder into a sheet; In the apparatus for manufacturing a foamed thermoplastic resin sheet having a decompression chamber for further foaming the extruded foamable thermoplastic resin body, at least a part of a wall surrounding the decompression chamber includes a plurality of vacuum holes. Consisting of members having
The evacuation is performed through the member.

According to the above configuration, the evacuation of the decompression chamber is performed through the porous member described in claim 2, which is a member having a plurality of evacuation holes. Even if the foaming thermoplastic resin body or foaming thermoplastic resin body comes into contact with the wall surface, it does not become impossible to draw a vacuum unlike the manufacturing equipment that was performed through the conventional suction port, and also has a cooling effect Go up. In addition, as a member having a plurality of vacuum holes, a member provided with a large number of slits having a fine slit width may be considered in addition to the porous member described above.

Therefore, the volume of the decompression chamber can be reduced to the limit according to the dimensions of the foamed thermoplastic resin sheet to be produced, and the production apparatus for the foamed thermoplastic resin sheet can be downsized.

In the apparatus for producing a foamed thermoplastic resin sheet according to the present invention, the diameter of the vacuum drawing hole of the porous member is
It is desirable that the thickness be 100 μm or less (the configuration according to claim 3). With such a configuration, an additive in a resin forming a foamable thermoplastic resin body in a vacuum drawing hole,
The desired degree of vacuum can be realized without causing a problem such as clogging of the molten resin and the decomposed resin. The diameter of the evacuation hole of the porous member is more preferably 5 mm.
It is 0 μm or less, and more preferably 30 μm or less.

Further, in the apparatus for producing a foamed thermoplastic resin sheet of the present invention, the porous member may be constituted by a porous electroformed shell.

In the apparatus for producing a foamed thermoplastic resin sheet according to the present invention, the porous member may be made of a sintered alloy.

A porous electroformed shell or a sintered alloy has a pore size of 1
Since it has a required strength of not more than 00 μm, the apparatus for producing a foamed thermoplastic resin sheet according to claim 2 or 3 can be easily realized by using such a material as a porous member. .

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the present invention will be described below with reference to FIGS.

As shown in FIG. 1A, the apparatus for manufacturing a foamed thermoplastic resin sheet according to the present embodiment includes an extruder 1, a head 2, a die 3, a decompression chamber 4, and a take-off machine 5. . The decompression chamber 4 is formed inside the molding section 9.

The extruder 1 melts and kneads the foaming agent and the thermoplastic resin at a temperature preset according to the thermoplastic resin and the foaming agent to be used, and extrudes the kneaded material in the direction of the head 2. It is. The extruder 1 preferably has a single screw structure when it is necessary to knead the foaming agent and the thermoplastic resin at a low temperature.

When the thermoplastic resin to be used is, for example, a polypropylene resin, the extruder 1 is set at a temperature close to the outlet of the extruder 1 by melting the polypropylene resin (kneaded product) which is a foamable thermoplastic resin body. The body temperature is set to be below 180 ° C. This is because outgassing occurs when the temperature of the melt of the polypropylene-based resin exceeds 180 ° C.

The head portion 2 is provided at the outlet of the extruder 1 and uses a screen mesh used for ordinary extrusion molding. However, when the thermoplastic resin to be used is a resin generating remarkable shear heat, a screen mesh is not used.

The die 3 is connected to the extruder 1 via the head 2.
This is a sheet die for processing the extruded foamable thermoplastic resin body into a sheet shape. Usually, the sheet die has a structure capable of adjusting the temperature and the pressure. The die 3 has a die lip 3a serving as a resin discharge port.

The take-off machine 5 is for taking out the foamed thermoplastic resin sheet 6 from the outlet side of the decompression chamber 4, and is disposed on the outlet side of the decompression chamber 4. The take-off machine 5 may be a belt or the like, but preferably a roll is used. When a roll is used, it is composed of a pair or more of rolls 5a facing each other which can nip the foamed thermoplastic resin sheet 6. The rolls 5a facing each other in pairs are movable in a direction in which the gap between them is reduced and in a direction in which they are widened. For example, these rolls 5a
Is configured to move with the movement of the movable upper wall portion 12 and the movable lower wall portion 13 described later. It is desirable that the roll 5a has a configuration in which the temperature can be adjusted by cooling water.

The take-up speed of the take-up machine 5 is appropriately set depending on the expansion ratio, thickness, resin composition and the like of the foamed thermoplastic resin sheet 6, but is usually 1 to 3 m / min.

The decompression chamber 4 is provided with a sheet-like foaming thermoplastic resin body extruded from the die 3 (hereinafter referred to as a sheet-like foaming thermoplastic resin sheet 6 in order to distinguish it from the foaming thermoplastic resin sheet 6 in the final foaming state). The resin body 6a), that is, the sheet-like foamable thermoplastic resin body 6a is exposed to a reduced pressure to further foam. The decompression chamber 4 has a structure capable of cooling the sheet-like foamable thermoplastic resin body 6a after further foaming the sheet-like foamable thermoplastic resin body 6a.

The inlet side of the decompression chamber 4 is a foaming zone 7 where the sheet-like foamable thermoplastic resin body 6a extruded from the die 3 is foamed under reduced pressure. The cooling zone 8 is a region where the sheet-like foamable thermoplastic resin body 6a foamed in the foaming zone 7 is cooled and solidified. The foaming zone 7 and the cooling zone 8
It is not necessary to strictly partition with a partition plate or the like. The pressure in the foaming zone 7 is preferably lower than that of the cooling zone 8, and also has a function of cooling the sheet-like foamable thermoplastic resin body 6a after highly foaming it. The cooling zone 8 is a zone for solidifying the sheet-like foamable thermoplastic resin body 6a.

The evacuation of the decompression chamber 4 is performed by an evacuation pump 17 connected to the bubbling zone 7 via an inner wall portion 14 having a below-described evacuation hole provided in each of the bubbling zone 7 and the cooling zone 8. Done. Adjustment of the degree of pressure reduction is performed by the pressure regulating valve 15 and the vacuum breaking valve 16. In addition,
In adjusting the degree of pressure reduction, both the pressure regulating valve 15 and the vacuum breaking valve 16 may be used in combination, or only one of them may be used. Further, here, the vacuum zone 17 and the cooling zone 8 are simultaneously evacuated by one vacuum pump 17, but a separate vacuum pump is also provided in the cooling zone 8, and the two zones 7.8 It is good also as a structure which can adjust a decompression degree each separately. Further, it is preferable that a pressure adjusting valve is provided in each of the evacuation lines so that the degree of pressure reduction can be adjusted. As the above-mentioned pressure adjusting valve, a commonly used one, for example, a type in which the suction pressure of the vacuum pump 17 is controlled while changing the opening degree of the valve via a pressure detector / transmitter, or a type in which a pressure gauge is monitored. A type that controls pressure by itself can be used.

The degree of decompression of the decompression chamber 4 is generally 100 mm
Hg or higher (differential pressure from atmospheric pressure), but when the thermoplastic resin used is, for example, a polypropylene resin, 200
A differential pressure of about mmHg (difference from atmospheric pressure) is required, preferably 300 mmHg or more, more preferably 350 to
That is, the differential pressure is set to 700 mmHg. However, the optimum degree of reduced pressure varies depending on the thermoplastic resin and the foaming agent used, and also varies depending on the desired expansion ratio of the foamed thermoplastic resin sheet 6.

Next, the molding section 9 and the decompression chamber 4 will be described in detail. FIG. 1A and FIG. 1B
As shown in FIG. 2 (a state in which the sheet-like foamable thermoplastic resin body 6a is omitted) which is a cross-sectional view taken along the line AA in FIG. It has an upper wall portion 12 and a movable lower wall portion 13. The space surrounded by the movable upper wall portion (wall portion) 12, the movable lower wall portion (wall portion) 13, and the outer wall portion (wall portion) 11 is the decompression chamber 4. In the present embodiment, the wall surface 12a as the lower surface of the movable upper wall portion 12 and the wall surface 13a as the upper surface of the movable lower wall portion 13 are flat surfaces. The movable upper wall portion 12 and the movable lower wall portion 13 have an inner wall portion 14 on the surface on the decompression chamber 4 side, and the inner wall portion 14 defines the wall surfaces 12a and 13a.

The forming section 9 includes a movable wall driving device 23 for moving the movable upper wall section 12 and the movable lower wall section 13. In order to configure the movable wall driving device 23, lower ends of a plurality of screws 24 provided vertically through the outer wall 11 are connected to the upper surface of the movable upper wall 12. The portions of the screws 24 protruding from the outer wall portion 11 are screwed to female screw portions (not shown) formed on the sprocket 25. These sprockets 25 are rotatably provided on the upper surface of the outer wall portion 11. A rotatable handle 26 is provided on the upper surface of the outer wall portion 11, and the sprocket 27 can be rotated by the handle 26. The above sprocket 25
As shown in FIG. 1B, for example, a toothed belt 28 is hung on the 27. Note that a chain may be used instead of the belt 28.

Similarly, the screw 24, the sprocket 25, the sprocket 27, and the belt 28 are provided on the lower surface side of the movable lower wall portion 13. However, the handle 26 is not provided on the lower surface, and the handle 2 on the upper surface is not provided.
The rotation of No. 6 is transmitted to the lower surface side sprocket 27 by a drive transmission mechanism (not shown). An independent movable wall driving device 23 similar to the upper surface side is also provided on the lower surface side, and the movable upper wall portion 12 and the movable lower wall portion 13 are moved by individual handles 26, that is, the movable wall driving device 23. It may be.

With the above configuration, when the handle 26 is rotated, the movable upper wall portion 12 and the movable lower wall portion 13 can be moved up and down simultaneously. In this case, the movable upper wall 12
And the movable lower wall 13 move in the opposite direction. This allows
Wall surface 12a of movable upper wall portion 12 and wall surface 1 of movable lower wall portion 13
The height of the decompression chamber 4 corresponding to the distance from the pressure reducing chamber 3a, that is, the thickness of the foamed thermoplastic resin sheet 6, can be adjusted.

The movement of the movable upper wall portion 12 and the movable lower wall portion 13 is performed by moving the movable upper wall portion 12 and the movable lower wall portion 13.
Is not inclined in any of the extrusion direction and the width direction of the foamed thermoplastic resin sheet 6, and is preferably performed in a state where they are kept parallel to each other.

In the present embodiment, the moving distance between the wall surface 12a of the movable upper wall portion 12 and the wall surface 13a of the movable lower wall portion 13 with respect to the center position in the thickness direction of the foamed thermoplastic resin sheet 6 at the die lip 3a. Are generally substantially the same, but may be different depending on conditions.

The movable wall driving device 23 includes:
Not only the above-described screw type configuration but also a known configuration such as a configuration using a hydraulic cylinder can be used as appropriate. The screw-type movable wall driving device 23 is suitable for a small-sized manufacturing device,
The hydraulic cylinder type is suitable for a large-sized manufacturing device.

In this embodiment, the movable upper wall portion 12 and the movable lower wall portion 13 are provided, but only one of them is provided as being movable. Is also good.

A blade-shaped seal member 31 is provided at each of the movable upper wall portion 12 and the movable lower wall portion 13 at the outlet side end of the decompression chamber 4. These seal members 31 are provided, for example, from the left and right ends of the movable upper wall portion 12 and the movable lower wall portion 13 to the other end. These seal members 31
In a state where the sheet-like foamable thermoplastic resin body 6a or the foamed thermoplastic resin sheet 6 is interposed between the sheets 31, the sheet 31 is bent or bent in the transport direction thereof, and the decompression chamber 4 is sealed so that the pressure can be reduced. The seal member 31 is soft and flexible, and is preferably formed of, for example, rubber.

The seal members 31 may be provided in the thickness direction on both sides of the foamed thermoplastic resin sheet 6 in addition to the above range. The sealing member 31 in the thickness direction is the outer wall portion 11.
Is provided. Further, the seal member 31 may be provided corresponding to only one of the upper and lower width directions of the sheet-like foamable thermoplastic resin body 6 a or the foamed thermoplastic resin sheet 6.

In the decompression chamber 4, first, the foaming zone 7
Is a zone for highly foaming the sheet-like foamable thermoplastic resin body 6a adjusted to a temperature suitable for foaming from the die 3 and extruded. The pressure in this zone is reduced. During the production operation of the continuous foamed thermoplastic resin sheet 6, the foaming zone 7 has a thickness corresponding to the opening thickness of the die lip 3 a.
A state spread on the spacing W ₂ of stretch both walls 12a · 13a.

The evacuation of the foaming zone 7
This is performed through a member having a vacuum hole disposed on a part of or the entire surface of the surrounding wall.

The evacuation is performed by reducing the pressure in the thickness direction of the sheet-like foamable thermoplastic resin body 6a, reducing the pressure in the direction perpendicular to the thickness direction (width direction), and further reducing the pressure in both directions. The pressure may be reduced in the thickness direction.

More preferably, for example, the movable upper wall 12
In the above, vacuum evacuation holes having a diameter of 20 mm or less are provided at both ends in the width direction to reduce the pressure in the thickness direction. When the diameter of the vacuum drawing hole is 20 mm or more, the molten resin or the like is easily clogged, and in this case, the operation of taking the foamed thermoplastic resin sheet 6 by the take-up machine 5 is stopped.

In the present embodiment, the movable upper wall 12
The inner wall 14 of the movable lower wall 13 is formed of a member having a vacuum hole. As this member, a porous member such as a sintered alloy or a porous electroformed shell is particularly preferably used.

As a porous electroformed shell which is one of the porous members, there is porous electroformed (registered trademark), and FIG.
(B) schematically shows a cross section of the inner wall portion 14 made of porous electroforming. In the porous electroforming, the vent hole H has a structure that widens greatly on the back, and is characterized in that clogging hardly occurs and gas vent resistance is low. Porous electroforming is an electroforming mold that performs metal inversion by thickly plating a metal such as nickel on a model.

As shown in FIG. 5B, the front side is thicker than that shown in FIG. 5A, so that the surface processing becomes easier and the pressure resistance is increased. . The number of holes in the porous electroforming is usually 3 to 7 holes / cm ² , preferably 3 to 5 holes / cm ² . Above that, there will gradually be problems with strength.

A vacuum hole (not shown) in the inner wall portion 14
Should be at least 100 μm or less, preferably 50 μm or less, and more preferably 30 μm or less. If the evacuation hole is large, the additive, the molten resin and the decomposed resin in the thermoplastic resin to be used will
The vacuum pump 17 needs to be large in size in order to keep the desired degree of reduced pressure.

Further, the inner wall portion 14 located in the foaming zone 7
Is maintained at a predetermined temperature by the cooling water flowing through the cooling water channel 18 embedded in the inner wall portion 14. When a metal having high thermal conductivity is used as the material of the inner wall portion 14, the cooling effect is increased. The cooling water channel 18 may be one that cools the entire foaming zone 7 with one line. However, in order to favorably maintain the foaming state of the sheet-like foamable thermoplastic resin body 6a under reduced pressure, a plurality of lines extending in the width direction of the sheet-like foamable thermoplastic resin body 6a are each independently extended in the extrusion direction. The configuration provided so as to line up is preferable.

The means for adjusting the temperature of the foaming zone 7 is not particularly limited as long as the temperature can be adjusted. For example, a configuration in which air is blown into the foaming zone 7 is also possible. In the case of adopting this configuration, if a vacuum evacuation is performed in the foaming zone 7 which is superior to air blowing, the decompression chamber 4
The overall degree of decompression can be maintained.

Here, since the entire surface or almost the entire surface of the sheet-like foamable thermoplastic resin body 6a comes into contact with the inner wall portion 14 of the foaming zone 7, the temperature of the inner wall portion 14 becomes lower than the sheet-like foamable thermoplastic resin body 6a. And the temperature control effect is high.

In such a configuration of the foaming zone 7, the sheet-like foamable thermoplastic resin body 6a is dragged while being in contact with the inner wall portion 14 located in the foaming zone 7. The surface of the thermoplastic resin body 6a is scratched or hardly flows.

Therefore, the inner wall portion 1 located in the foaming zone 7
4, that is, on the wall surfaces 12 a and 13 a, FIG.
As shown in (b), many small protrusions 21 are formed. The projections 21 shown in FIGS. 7A and 7B have curved surfaces and independent shapes. As a result of providing such a convex portion 21, the wall surfaces 12a and 13a
Has an uneven structure. By providing irregularities on the wall surfaces 12a and 13a by this uneven structure, the wall surfaces 12a and 13a and the sheet-like foamable thermoplastic resin body 6a are formed.
(For example, a sheet-like foamable polypropylene resin body) to reduce the contact area with the sheet-like foamable thermoplastic resin body 6.
makes a slippery. That is, the wall surfaces 12a and 13a
In order to reduce the contact area with the sheet-like foamable thermoplastic resin body 6a (for example, the sheet-like foamable polypropylene-based resin body), it is sufficient that the surface is not a flat surface but a surface having an uneven height.

Due to the irregularities, the contact area between the wall surfaces 12a and 13a and the sheet-like foamable thermoplastic resin body 6a is preferably 10% or more and 80% or less in the case where there is no irregularity. If the contact area is less than 10%, the contact area between the sheet-like foamable thermoplastic resin body 6a and the wall surfaces 12a and 13a is too small, so that it is difficult to sufficiently cool the sheet-like foamable thermoplastic resin body 6a. If the contact area is larger than 80%, it may be difficult to take off the sheet-like foamable thermoplastic resin body 6a.

More desirably, the above-mentioned convex portion 21 or the wall surfaces 12a and 13a having the convex portion 21 are subjected to plating treatment, for example, Teflon plating. Thereby, the flow of the sheet-like foamable thermoplastic resin body 6a is further improved, and the possibility of damaging the surface thereof is further reduced.

The uneven pattern formed by the convex portions 21 shown in FIGS. 3A and 3B is an example, and there is no particular limitation on the pattern. For example, a grain pattern or a satin pattern is preferably used. It is more preferable that the formation and plating of the concavo-convex pattern be performed not only on the wall surfaces 12a and 13a of the foaming zone 7 but also on the side wall surface of the outer wall portion 11 (see FIG. 2) surrounding the foaming zone 7. You may go only to. When a porous member is used for evacuation, the foaming zone 7
Although it is preferable to perform the formation and plating of the uneven pattern on both the metal surface and the porous member forming the inner wall of the
Either one may be formed.

FIGS. 3 (a) and 3 (b) show a configuration having convex portions 21 of different sizes, but the convex portions 21 are the same as shown in FIGS. 4 (a) and 4 (b). May be arranged in parallel. Further, the shape of the convex portion 21 is curved (FIG. 3A, FIG.
Although (a) is preferable, the shape is not limited to this, and it may be substantially pyramidal or conical (FIG. 4B).

The apparent coefficient of friction k between the sheet-like foamable thermoplastic resin body 6a and the wall surfaces 12a and 13a is 0.4 or less by forming an uneven pattern on the wall surfaces 12a and 13a and performing, for example, Teflon plating. It is preferable that Here, the apparent friction coefficient k is a value defined by the following equation.

(Differential pressure between pressure in decompression chamber 4 and atmospheric pressure) ×
(Area of wall surface 12a (or wall surface 13a)) × apparent friction coefficient k = tensile force The apparent friction coefficient k is preferably 0.35
Or less, more preferably 0.32 or less. this is,
If the apparent coefficient of friction k is larger than 0.4, the take-up of the foamed thermoplastic resin sheet 6 by the take-off machine 5 may stop.

On the other hand, the cooling zone 8 is a zone for cooling and solidifying the foamed thermoplastic resin sheet 6 foamed in the thickness direction in the foaming zone 7. The structure for evacuating the cooling zone 8 is the same as that of the foaming zone 7, and evacuating is performed via a member having an evacuated hole. As the member having the evacuation hole, a porous member is also desirable, and in this case, the conditions and arrangement conditions of the evacuation hole diameter, the materials preferably used are the same as those described in the foaming zone 7. is there. However, in the cooling zone 8, the number of vacuum holes may be smaller than in the foaming zone 7. When porous electroforming is used as the porous member, the number of holes in the porous electroforming may be any, but preferably 3
Pieces / cm ² or less.

It is preferable that the degree of pressure reduction in the cooling zone 8 is lower than that in the foaming zone 7 (a pressure close to the atmospheric pressure). In this case, there is an advantage that the take-up machine 5 can easily take out the foamed thermoplastic resin sheet 6.

In the cooling zone 8 as well, the entire or almost the entire surface of the foamed thermoplastic resin sheet 6 is covered with the cooling zone 8.
, The temperature of the inner wall portion 14 is sufficiently transmitted to the foamed thermoplastic resin sheet 6 and the cooling effect is enhanced.

Also in the cooling zone 8, similarly to the foaming zone 7, the foamed thermoplastic resin sheet 6 is to be dragged, so that the inner wall thereof is formed with, for example, projections and depressions 21. And more preferably,
This is plated.

The means for adjusting the temperature of the cooling zone 8 is not particularly limited as long as the temperature can be adjusted. For example, a configuration in which air is blown into the cooling zone 8 is also possible. In the case of adopting this configuration, if a vacuum is applied in the cooling zone 8 that is superior to blowing air, the decompression chamber 4
The overall degree of decompression can be maintained. In particular, when this configuration is employed, there is an advantage that the contact between the foamed thermoplastic resin sheet 6 and the inner wall is reduced, and the take-up of the foamed thermoplastic resin sheet 6 becomes easier.

At the outlet of the cooling zone 8, the center temperature of the foamed thermoplastic resin sheet 6 is preferably lower than the center temperature of the sheet-shaped foamable thermoplastic resin body 6 a at the outlet of the die 3 by 50 ° C. or more. This makes it possible to maintain the bubbles that have grown in the thickness direction of the foamed thermoplastic resin sheet 6 under reduced pressure.

When the apparatus for manufacturing a foamed thermoplastic resin sheet having the above-described structure is used, the foamed thermoplastic resin sheet 6 can be obtained by the following method.

First, after the foaming agent and the thermoplastic resin are melted and kneaded by the extruder 1, the kneaded material is extruded from the die 3 into a sheet-like foamable thermoplastic resin body 6a. At this time, as shown in FIG. 5 (a), the manufacturing apparatus sets the movable upper wall portion 12 and the movable upper wall portion 12 in a state where the movable upper wall portion 12 is moved up by the movable wall driving device 23 and the movable lower wall portion 13 is lowered. The movable lower wall portion 13 is disposed, and the wall surfaces 12a and 13
The interval a is set to be larger than the thickness of the sheet-like foamable thermoplastic resin body 6a.

The sheet-like foamable thermoplastic resin body 6 a extruded from the die 3 reaches the take-up machine 5 through the decompression chamber 4, and is brought into a state where it can be taken out by the take-up machine 5. At this time, the distance between the opposing rolls 5a is reduced in accordance with the thickness of the sheet-like foamable thermoplastic resin body 6a.

Next, the sheet-like foamable thermoplastic resin body 6a
While the continuous extrusion, the movable wall driving device 23, FIG. 5 (b), the on movable in such a manner as to narrow the interval between the wall surface 12a · 13a until W ₁ wall 12 and the movable lower wall portion 13 is moved. The above-mentioned interval W ₁ corresponds to the thickness of the sheet-like foamable thermoplastic resin body 6 a extruded from the die 3 in a state where the pressure in the decompression chamber 4 is not reduced. In this state, the end of the seal member 31 reaches the surface of the sheet-like foamable thermoplastic resin body 6a sufficiently and covers the outlet of the decompression chamber 4, so that the decompression chamber 4 can be decompressed. At this time, the seal member 31 can be in contact with the surface of the sheet-shaped foamable thermoplastic resin body 6a in a state where the seal member 31 is bent or bent toward the moving direction side of the sheet-shaped foamable thermoplastic resin body 6a.

Thereafter, the pressure reducing chamber 4 is set at 100
As shown in FIG. 1A, the pressure is reduced by a reduced pressure of not less than mmHg, and the movable wall driving device 23
· 13a interval between moves the movable upper wall 12 and the movable lower wall portion 13 to extend up to W _2. The above interval W
_2, which corresponds to the desired thickness of the foamed thermoplastic resin sheet 6 to be produced, the interval W ₂ can be arbitrarily changed. The upper limit of the reduced pressure amount is 700 mmHg.
It is preferable to set the following. With such a setting, the foaming thermoplastic resin sheet 6 can be smoothly taken out of the decompression chamber 4.

By the above-described depressurizing operation, the sheet-like foamable thermoplastic resin body 6 a further foams by passing through the foaming zone 7, and becomes the foamed thermoplastic resin sheet 6. The foamed thermoplastic resin sheet 6 is cooled and solidified by passing through the subsequent cooling zone 8, and then is taken by the take-up machine 5. In the case where continuously producing foamed thermoplastic resin sheet 6, a vacuum chamber 4 as well as vacuum as described above, manufacturing operation is continuously in a state where the distance between the wall surfaces 12a · 13a is fixed to W ₂ Done.

As described above, in the present manufacturing apparatus, the distance W ₂ between the wall surfaces 12a and 13a during the continuous production of the foamed thermoplastic resin sheet 6 can be arbitrarily set by the movable wall driving device 23. Expanded thermoplastic resin sheet 6
Can be manufactured. Therefore, it is possible to cope with the production of the foamed thermoplastic resin sheet 6 having various thicknesses, and it has high versatility.

The distance between the wall surface 12a of the movable upper wall portion 12 and the wall surface 13a of the movable lower wall portion 13 is set by the movable wall driving device 23 before the decompression of the decompression chamber 4 is started and the sheet-like foaming thermoplastic resin is formed. When the resin body 6a is not foamed by the reduced pressure and has a small thickness, it is narrowed. When the sheet-like foamable thermoplastic resin body 6a is foamed by the reduced pressure and becomes thicker after the start of the decompression of the decompression chamber 4, that is, the foaming is performed. It can be expanded when it becomes the thermoplastic resin sheet 6. Therefore, before and after the start of depressurization of the decompression chamber 4, the distance between the wall surfaces 12a and 13a and the sheet-like foamable thermoplastic resin body 6a or the foamed thermoplastic resin sheet 6, that is, the seal member 31 and the sheet-like foamable heat The positional relationship in the thickness direction of the sheet-like foamable thermoplastic resin body 6a (sheet 6) with the thermoplastic resin body 6a or the foamed thermoplastic resin sheet 6 can be kept substantially constant.

As a result, the surface of the foamed thermoplastic resin sheet 6 is damaged by the pressing force of the seal member 31 while maintaining the sealed state in which the pressure can be reduced by the seal member 31 in the decompression chamber 4, or the foamed thermoplastic resin sheet 6 Can be prevented from being crushed. As a result, it is possible to easily obtain the foamed thermoplastic resin sheet 6 in which the surface condition is good, the effect of bubble growth by the reduced pressure is sufficiently obtained, and the cells are sufficiently grown in the thickness direction.

In this manufacturing apparatus, the die lip 3a of the die 3 may be configured to protrude from the inlet of the decompression chamber 4 as shown in FIG. With such a structure, as shown in FIG.
In a state in which the distance between a and the die 3, that is, a part of the sheet-like foamable thermoplastic resin body 6 a extruded from the die lip 3 a is, for example, the movable upper wall portion 12 or the movable lower wall portion 13 and the die 3. It is possible to prevent a situation in which the sheet-like foamable thermoplastic resin body 6a is disturbed by being drawn into the gap between the sheet-like foamable thermoplastic resin bodies 6a.

The thermoplastic resin usable as the material of the foamed thermoplastic resin sheet 6 is not particularly limited.
Generally, resins used for extrusion molding and injection molding are applied. Examples thereof include polyolefin resins such as polyethylene and polypropylene, polystyrene, polyvinyl chloride, polyamide, acrylic resin, polyester, polycarbonate, and copolymers of these resins. In particular, it is preferable to use a polypropylene resin. The polypropylene resin may be any of a homopolymer, a block copolymer, and a random copolymer. Further, a mixture of these and another olefin resin may be used. In this case, the polyolefin resin to be mixed is preferably a polyolefin having 10 or less carbon atoms, such as polyethylene or polybutene, and more preferably a polyethylene resin. When a polypropylene resin is mixed with another polyolefin resin, the ratio of the polypropylene is 5%.
0 wt% or more.

As a more preferred polypropylene resin, a propylene polymer having improved melt strength can be used. Such a propylene-based polymer can be obtained by, for example, a method of polymerizing components having different molecular weights in multiple stages, a method of using a specific catalyst system, or a method of performing post-treatment such as crosslinking on the propylene-based polymer. Among them, a method of polymerizing components having different molecular weights in multiple stages is preferable from the viewpoint of productivity.

The above-mentioned thermoplastic resin may contain various commonly used additives such as a filler such as talc, a pigment, an antistatic agent and an antioxidant. The foaming agent applied to the present invention is not particularly limited, and various foaming agents such as a physical foaming agent and a chemical foaming agent can be used.

The apparatus for producing the foamed thermoplastic resin sheet 6 may have the structure shown in FIGS. In this manufacturing apparatus, the upper wall and the lower wall forming the decompression chamber 4 of the molding unit 9 are formed by a fixed upper wall 41 and a fixed lower wall 42 on the front side.
And a movable upper wall portion 12 and a movable lower wall portion 13 on the rear side. A foaming zone 7 is formed between opposing wall surfaces 41a and 42a of the fixed upper wall portion 41 and the fixed lower wall portion 42. The wall surfaces 41a and 42a are gently curved or inclined so that the interval gradually increases from the entrance to the exit of the foaming zone 7. Spacing wall 41a · 42a, the inlet side is set to W _1, the outlet side is set to W _3. The interval W ₃ being for example of the foam manufacturing frequent some thickness thermoplastic resin sheet 6, which corresponds to the thickness of the thinnest ones. Therefore, in this case, when manufacturing a foamed thermoplastic resin sheet 6 of the thinnest thickness, spacing W ₃ being equal to the distance W _2. As described previously, the spacing W ₂ are those corresponding to the desired thickness of the foamed thermoplastic resin sheet 6 to be produced.

The sheet-like foamable thermoplastic resin body 6a extruded from the die 3 is foamed gently in the thickness direction along the shape of the wall surfaces 41a and 42a when exposed to reduced pressure in the foaming zone 7. . And foaming zone 7
Of it with the thickness of the spacing W ₃ at the end portion, the thickness of the spacing W ₂ of the above at the inlet of the cooling zone 8.

The opposing wall surfaces 12 a and 13 a of the movable upper wall portion 12 and the movable lower wall portion 13 form a cooling zone 8. These wall surfaces 12a and 13a are, as described above,
A flat surface, and driven by the movable wall driving device 23,
It can move in the approaching direction and the separating direction from each other.

The operation of the movable upper wall portion 12 and the movable lower wall portion 13 during the production of the foamed thermoplastic resin sheet 6, the sealing member 31
And the pressure reduction operation are the same as those of the manufacturing apparatus shown in FIGS. 1A and 1B, and the state of FIG.
8 (a) and 8 (b) correspond to the states of FIGS. 5 (a) and 5 (b), respectively.

In the present manufacturing apparatus, the sheet-shaped foamable thermoplastic resin body 6a extruded from the die 3 is smoothly guided by the gradually widening structure of the wall surfaces 41a and 42a, so that the take-up machine 5 can take the sheet-like foamable thermoplastic resin body smoothly. Can be. In addition, the functions and the like due to the movable wall surfaces 12a and 13a and the provision of the seal member 31 are as described above.

Further, the apparatus for producing the foamed thermoplastic resin sheet 6 may have the structure shown in FIGS. 9 and 10. As shown in FIG. 9, the manufacturing apparatus includes a temperature adjustment zone 51 inside the forming section 9 and before the decompression chamber 4. Fixed upper wall portion 52 forming temperature adjustment zone 51
The fixed lower wall portion 53 has an inner wall portion 57 made of a metal having high thermal conductivity. A temperature adjusting medium flow passage 54 through which a temperature adjusting fluid flows is provided inside or outside the inner wall portion 57.

The temperature adjustment zone 51 is a zone for adjusting the surface temperature of the sheet-like foamable thermoplastic resin body 6a extruded from the die 3 within a predetermined temperature range. That is, the sheet-shaped foamable thermoplastic resin body 6a is heated to a predetermined set temperature by the heat from the temperature adjusting medium flow path 54. With the temperature adjustment zone 51, the temperature at the time of foaming in the foaming zone 7 can be adjusted, and the foamed thermoplastic resin sheet 6 can be manufactured more stably.

The above set temperature is determined according to the thermoplastic resin and the foaming agent to be used. When the thermoplastic resin is, for example, a crystalline resin, the temperature of the sheet-like foam at the exit of the die 3 is higher than the crystallization temperature of the resin to be used. The temperature is set to be equal to or lower than the temperature of the thermoplastic resin body 6a.

For example, when a polypropylene resin is used as the thermoplastic resin, the temperature adjustment zone 51
C. to 180 ° C., and the sheet-like foamable thermoplastic resin body 6 is set to fall within a range of about ± 2 ° C. of the set temperature.
Adjust the surface temperature of a.

The means for heating the inner wall portion 57 is not limited to the above-mentioned temperature adjusting medium flow passage 54,
Generally, there is no particular limitation as long as the temperature can be adjusted and the inner wall portion 57 can be maintained at the set temperature.

The sheet-like foamable thermoplastic resin body 6a
When the entire surface of the inner wall portion 57 is in contact with the inner wall portion 57, the surface temperature of the sheet-like foamable thermoplastic resin body 6a can be accurately adjusted.
Spacing 53a is that it is desirable, and with adjustable spacing of the wall 52a · 53a configuration if the thickness of the sheet-like expandable thermoplastic resin material 6a extruded from the die 3 is substantially the same as W ₁ of about Is desirable. However, it is not necessary that the entire surface of the sheet-like foamable thermoplastic resin body 6a be in contact with the inner wall of the temperature adjustment zone 51.

Further, the above-mentioned manufacturing apparatus is shown in FIG.
As shown in (b), the forming part 9 having the temperature adjustment zone 51 and the die 3 are provided separately, and at least one pair of rolls 55 is provided at the entrance of the temperature adjustment zone 51.
And the sheet-like foamable thermoplastic resin body 6 a extruded from the die 3 may be taken into the temperature adjustment zone 51 via the rolls 55. Also,
In this manufacturing apparatus, as shown in FIG.
A pair of cutters 56 for adjusting the width of the sheet-like foamable thermoplastic resin body 6a may be provided on both sides of the inlet of the temperature adjustment zone 51 in the sheet width direction.

In the configuration in which the rolls 55 are provided, the thickness of the sheet-like foamable thermoplastic resin body 6a before entering the decompression chamber 4 can be adjusted. Body 6a in temperature adjustment zone 5
It becomes easy to draw into 1.

It is desirable that the pair of rolls 55 is capable of adjusting the temperature, and the set temperature is appropriately set according to the thermoplastic resin or foaming agent to be used, the thickness of the foamed thermoplastic resin sheet 6, and the like. is there. However, the temperature is preferably equal to or lower than the temperature of the sheet-shaped foamable thermoplastic resin body 6a at the exit of the die 3, and equal to or higher than the temperature set in the temperature adjustment zone 51.

The cutters 56 need not always be provided, but are preferably provided from the following points. That is, by cutting the sheet width of the sheet-shaped foamable thermoplastic resin body 6a according to the width of the passage in the temperature adjustment zone 51 by the cutters 56, the sheet-shaped foamable thermoplastic resin body 6a is cut into the temperature adjustment zone. It becomes easy to be pulled into the inside of 51.

The apparatus for producing the foamed thermoplastic resin sheet 6 may have the structure shown in FIGS. 11 (a) and 11 (b).
The manufacturing apparatus includes a die 3 for processing the expandable thermoplastic resin body extruded from the extruder 1 through the head portion 2 into a sheet-like expandable thermoplastic resin body 6a, that is, a circular die 61 instead of the sheet die. It has. The circular die 61 is connected to the extruder 1 via the head 2.
The extruded foamable thermoplastic resin body is processed into a tubular foamable thermoplastic resin body 6b.

In the subsequent stage of the circular die 61,
The tubular foamable thermoplastic resin body 6b extruded into the atmosphere via the circular die 61 is cut in the extrusion direction, and is expanded into a sheet-shaped foamable thermoplastic resin body 6a.
Is provided with a cutter 62 that cuts through. Accordingly, the tubular foamable thermoplastic resin body 6b is cut open by the cutter 62 to form a sheet-like foamable thermoplastic resin body 6a.
Rolls 55 are taken into the decompression chamber 4.

The means for cutting the tubular foamable thermoplastic resin body 6b is not limited to the cutter 62, but may be any means capable of performing the above-described cutting processing.

Further, the present manufacturing apparatus is provided with the temperature adjustment zone 51 in the preceding stage of the decompression chamber 4. The function of the temperature adjustment zone 51 is as described above. Further, the above-mentioned roll 55 and cutter 56 are provided at the entrance of the temperature control zone 51, and the sheet-like foamable thermoplastic resin body 6a is provided.
Are preferable for taking the gas into the decompression chamber 4, but these are not essential.

Each of the above-described manufacturing apparatuses has a configuration in which the extruder 1, the die 3, and the decompression chamber 4 are arranged in a straight line in the horizontal direction. A configuration in which the pressure reducing chamber 4 is disposed so as to face downward and an extension line in the extrusion direction may be adopted.

Here, the results of observing the bubble shape of the foamed thermoplastic resin sheet 6 manufactured using each of the above manufacturing apparatuses are shown. As a result of this observation, the expansion ratio was 2.5 times or more, and in the cross section in the thickness direction of the obtained foamed thermoplastic resin sheet 6, the ratio exceeded 20% of the total thickness from both surfaces of the sheet 6, It was found that the shape of the bubbles existing at an inner position exceeding 15% of the sheet width from both side surfaces satisfied the following conditional expressions (1) and (2).

0.5 ≦ D / C ≦ 0.9 (1) 0.5 ≦ E / C ≦ 0.9 (2) where C is a value in the thickness direction of the foamed thermoplastic resin sheet 6. The average cell diameter, D, is the average cell diameter of the expanded thermoplastic resin sheet 6 in the extrusion direction, and E is the average cell diameter of the expanded thermoplastic resin sheet 6, in the sheet width direction.

[0099]

An embodiment of the present invention will be described below with reference to FIG. In the present embodiment, a mixture of polypropylene and polyethylene is used as the thermoplastic resin, and the mixing ratio is polypropylene: polyethylene = 70: 30 wt%.
And As a foaming agent and a foaming aid, the weight ratio of baking soda / azodicarboxylic acid amide / zinc oxide is 9 / 0.5.
3.5 parts by weight of a 30 wt% masterbatch (polyethylene base) of a composite blowing agent having a ratio of /0.5 was added.

The apparatus shown in FIG. 1 was used for producing the foamed thermoplastic resin sheet 6 here. Table 1 shows the settings of each unit in this device.

[0101]

[Table 1]

The cross section of the foamed thermoplastic resin sheet 6 manufactured using such a foamed thermoplastic resin sheet manufacturing apparatus was observed, and the cell diameter was measured. As a result, the above conditions (conditional expressions (1) and (2)) were obtained. )). Table 2 shows the results. For the comparative example, the same resin composition, foaming agent, extruder 1 and die 3 as in the example were used,
The result of cross-sectional observation of the foamed thermoplastic resin sheet extruded into the atmosphere is shown.

As the value of each cell diameter, as shown in FIG. 12, the maximum tangent interval of the tangent to each cell in the thickness direction, extrusion direction and width direction of the foamed thermoplastic resin sheet was adopted.

Further, (average cell diameter in the extrusion direction of the foamed thermoplastic resin sheet) / (average cell diameter in the thickness direction of the foamed thermoplastic resin sheet), that is, D / C was measured by the following method.

First, at an inner position exceeding 15% of the sheet width from both side surfaces of the foamed thermoplastic resin sheet,
An area of (sheet width direction) cm × 20 (extrusion direction) cm is selected, and a cross section parallel to the sheet extrusion direction and the thickness direction and a cross section parallel to the sheet width direction and the thickness direction are formed at three points in this area. Was cut out. Next, for each of these samples, a microscope enlarged photograph of a cross section parallel to the sheet extrusion direction in a region corresponding to an internal position exceeding 20% of the total thickness from both surfaces (front and back surfaces) of the foamed thermoplastic resin sheet was taken. From this photograph, c (diameter in the thickness direction) and d (diameter in the extrusion direction) are shown in FIG. 12 for each half or more of the bubbles existing in the 1 mm ² square area of the foamed thermoplastic resin sheet. Was measured by the following method. C ₁ , c ₂ ,
..., c _n and d _1, d _2, ..., from the value of d _n, c, d
C and D, which are average values, were obtained, and D / C was further obtained. Here, n ≧ 30.

Further, (average cell diameter in the width direction of the foamed thermoplastic resin sheet) / (average cell diameter in the thickness direction of the foamed thermoplastic resin sheet), that is, E / C was measured by the following method.

First, with respect to the above three samples, a microscope enlarged photograph of a cross section parallel to the sheet width direction in a region corresponding to an internal position exceeding 20% of the total thickness from both surfaces (front and back surfaces) of the foamed thermoplastic resin sheet. Taken. From this photograph, c (diameter in the thickness direction) and e (diameter in the width direction) are shown in FIG. 12 for more than half of the air bubbles existing in the square area of 1 mm ² of the foamed thermoplastic resin sheet. Was measured by the following method. C _1, c ₂ of all each region thus obtained, ..., c _n and e _1, e _2, ..., obtained from the value of e _n, c, is the average value of e C, the E, further E /
C was obtained. Here, n ≧ 30.

When the inside of the sheet exceeding 15% of the sheet width from both sides is less than 20 cm in length, sampling is performed so that the above-mentioned area becomes 400 cm ² , and the same as above. To obtain D / C and E / C.

The surface smoothness of the foamed thermoplastic resin sheet 6 was evaluated by the center line average surface roughness Ra. The center line average surface roughness Ra was measured according to JIS B0601. However, the measurement conditions are a cutoff value of 0.8 mm, a measurement length of 10 mm, a drive speed of 0.3 mm / S, and an average value of the measured values at five points.

[0110]

[Table 2]

Center line average surface roughness Ra (mm) ：: Ra ≦ 0.4 Δ: 0.4 <Ra ≦ 0.8 ×: 0.8 <Ra C: Average cell diameter in thickness direction D: Extrusion direction E: Average cell diameter in the width direction The foamed thermoplastic resin sheet 6 of the present example having the cell shape as described above was confirmed to have a high expansion ratio and a large thickness.

[0112]

As described above, in the apparatus for producing a foamed thermoplastic resin sheet according to the first aspect of the present invention, at least a part of the wall surrounding the decompression chamber is formed of a member having a plurality of vacuum holes. In this configuration, evacuation is performed via the member.

According to a second aspect of the present invention, there is provided an apparatus for producing a foamed thermoplastic resin sheet according to the first aspect, wherein the member having a plurality of vacuum holes is a porous member.

Thus, even if the foamable thermoplastic resin body or the foamed thermoplastic resin body (foamed thermoplastic resin sheet) comes into contact with the wall surface of the decompression chamber, it can be used as in the case of a manufacturing apparatus that has been performed through a conventional suction port. In addition, there is no possibility that vacuum cannot be drawn.

As a result, it is possible to reduce the size of the apparatus for manufacturing the foamed thermoplastic resin sheet.

According to a third aspect of the present invention, there is provided an apparatus for producing a foamed thermoplastic resin sheet according to the second aspect, wherein the diameter of the vacuum hole of the porous member is 100 μm or less.

As a result, the effect described in claim 1 can be obtained without causing a drawback that the additive in the resin forming the foamed thermoplastic resin body, the molten resin and the decomposed resin are clogged in the vacuum drawing hole. be able to.

Further, in the apparatus for producing a foamed thermoplastic resin sheet of the present invention, the porous member can be constituted by a porous electroformed shell (the structure described in claim 4).

Further, in the apparatus for producing a foamed thermoplastic resin sheet of the present invention, the porous member can be made of a sintered alloy.

As a result, there is an effect that the apparatus for manufacturing a foamed thermoplastic resin sheet according to claim 2 or 3 can be easily realized.

[Brief description of the drawings]

FIG. 1A is a schematic longitudinal sectional view showing an apparatus for producing a foamed thermoplastic resin sheet according to an embodiment of the present invention, and FIG. 1B is a plan view thereof.

FIG. 2 is a schematic sectional view taken along line AA in FIG. 1 (b).

FIG. 3 (a) is a schematic longitudinal sectional view showing the shape of porous electroforming usable as a porous member in the foaming zone and cooling zone shown in FIG. FIG. 3B is a schematic longitudinal sectional view showing another example of the structure shown in FIG.

4 (a) is a schematic longitudinal sectional view showing another example of the unevenness processing shown in FIG. 3 (a), and FIG.
It is a schematic longitudinal cross-sectional view which shows another example of the uneven | corrugated process shown in (a).

5 (a) is a schematic longitudinal sectional view showing a state at the start of extrusion of a sheet-like foamable thermoplastic resin body in the manufacturing apparatus shown in FIG. 1 (a), and FIG. 5 (b). Figure 5
FIG. 3 is a schematic longitudinal sectional view showing a state after the state shown in FIG.

FIG. 6 is a schematic longitudinal sectional view showing an example in which the die shown in FIG. 1A includes a die in which a die lip projects into a decompression chamber.

FIG. 7 is a schematic longitudinal sectional view showing another example of the apparatus for manufacturing a foamed thermoplastic resin sheet shown in FIG. 1 (a).

8A is a schematic longitudinal sectional view showing a state at the time of starting extrusion of a sheet-like foamable thermoplastic resin body in the manufacturing apparatus shown in FIG. 7, and FIG. FIG. 8 is a schematic longitudinal sectional view showing a state after the state shown in FIG.

9 is a schematic longitudinal sectional view showing still another example of the apparatus for producing a foamed thermoplastic resin sheet shown in FIG. 1 (a).

10 (a) is a schematic longitudinal sectional view showing still another example of the apparatus for manufacturing a foamed thermoplastic resin sheet shown in FIG. 1 (a), and FIG. 10 (b) is a plan view thereof. It is.

11A is a schematic longitudinal sectional view showing still another example of the apparatus for manufacturing a foamed thermoplastic resin sheet shown in FIG. 1A, and FIG. 11B is a plan view thereof. It is.

12 is an explanatory diagram of a method for measuring the cell diameter of a foamed thermoplastic resin sheet manufactured by the manufacturing apparatus shown in FIG. 1 according to one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Extruder 2 Head part 3 Dice 3a Die lip 4 Decompression chamber 5 Take-off machine 6 Expandable thermoplastic resin sheet 6a Sheet-like expandable thermoplastic resin body (expandable thermoplastic resin body) 6b Cylindrical expandable thermoplastic resin body (foam) 7 foaming zone 8 cooling zone 9 molding part 11 outer wall part (wall part) 12 movable upper wall part (wall part) 12a wall surface 13 movable lower wall part (wall part) 13a wall surface 14 inner wall part (wall part) ) 18 cooling water flow path 21 convex part 23 movable wall driving device 31 seal member 61 circular die 62 cutter

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 7:00 (72) Inventor Tatsuhiro Nagamatsu 2-1-1 Tsukahara, Takatsuki-shi, Osaka Sumitomo Chemical Co., Ltd.

Claims (5)

[Claims] 1. An extruder for melting and kneading a thermoplastic resin and a foaming agent, and an extruder provided at the tip of the extruder for melting and kneading.
An apparatus for producing a foamed thermoplastic resin sheet, comprising: a die for processing the kneaded foamable thermoplastic resin body into a sheet shape; and a decompression chamber for further foaming the foamable thermoplastic resin body extruded from the die. 3. The apparatus for producing a foamed thermoplastic resin sheet according to claim 1, wherein at least a part of the wall surrounding the decompression chamber is formed of a member having a plurality of vacuum holes, and the member is evacuated through the member. 2. The member having a plurality of vacuum holes,
The apparatus for producing a foamed thermoplastic resin sheet according to claim 1, wherein the apparatus is a porous member. 3. The method according to claim 1, wherein the diameter of the evacuation hole of the porous member is 10 or less.
The apparatus for producing a foamed thermoplastic resin sheet according to claim 2, wherein the thickness is 0 μm or less. 4. The apparatus for producing a foamed thermoplastic resin sheet according to claim 2, wherein said porous member is made of a porous electroformed shell. 5. An apparatus for producing a foamed thermoplastic resin sheet according to claim 2, wherein said porous member is made of a sintered alloy.