JPS5863426A - Manufacturing method and device for thermoplastic resin foaming substance - Google Patents

Abstract

PURPOSE:To enable an extruded product to be sufficiently foamed in a pressure reducing device and to continuously and efficiently obtain a high-foaming substance, by a method wherein an air shut-off means, being of a specified structure surrounding the extruded product, is attached to an outlet or an inlet of a pressure reducing chamber to close up the surroundings of the extruded product. CONSTITUTION:An air shut-off means 9 surrounding an extruded produt 10 is attached to an outlet or an inlet of a pressure reducing device 4. The surface, facing the extruded product, of the air shut-off means is formed of a flexible sheet 92 which is pressed against the surface of the extruded product 10 through injection of fluid into the shut-off means through a fluid pressure inlet 93. A wire net or a metallic foil is located between the flexible sheet 9a and the extruded product 10, enabling the sheet 92 to be prevented from wear and tear.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for producing a thermoplastic resin foam.

Thermoplastic resin foams can be manufactured continuously and efficiently by extrusion molding, so extrusion molding is preferably used for manufacturing resin foams. When producing foam by extrusion, in order to make the foam highly foamable, immediately after leaving the extruder, the extrudate is passed through a vacuum device connected to the die, and the extrudate is further heated under reduced pressure. It is known for foaming. In this case, since the extrudate continuously leaves the pressure reducing device, it is necessary to prevent air from entering from around the extrudate at the exit d of the pressure reducing device. For this purpose, it was carried out to attach a packing-like flat qEll sheet to the extrudate at the exit of the device, thereby blocking the air flow between the extrudate and the device.

As the flexible sheet, a flat sheet made of, for example, natural or synthetic rubber or soft resin was used. A flat sheet is placed f=J so as to span the outlet of the decompression device,
An opening was provided in the center for the extrudate to pass through, and the extrudate was forced to spread the opening and bend. but,
Simply attaching a flat sheet to the outlet of the decompression device to block the outlet is insufficient to restore airtightness at the outlet. This is because, in the case of foam production, the extrudate increases in volume during foaming, and the rate of volume increase varies greatly, and the cross-sectional shape and size of the extrudate are not fixed. Since it is not possible to keep up with these fluctuations by simply adding a sheet, it was necessary to make further improvements in order to maintain airtightness at the outlet of the pressure reducing device. This invention was born in response to this need.

In order to maintain airtightness at the outlet or inlet of a decompression chamber, the inventor formed a flexible sheet into a cylinder, arranged the sheet so as to surround the extrudate, and furthermore, part of the sheet surface The cylindrical sheet was positioned so as to face parallel to the surface of the extrudate, and was attached to the outlet or inlet of the vacuum chamber. Furthermore, the inventor provided a pressurized air chamber on the same side of the cylindrical sheet, and injected air into the chamber to cause the hook-shaped seeds to swell toward the extrudate. I tried to close the gap between me and things. As a result, it has been demonstrated that the extrudate can be kept airtight. This invention was made based on such confirmation.

The present invention involves extruding a melt-plasticized foamable thermoplastic resin composition from a die, passing the extrudate through a vacuum device connected to the die, and further foaming the extrudate in the vacuum device to wrinkle the foam. In this method, an air blocking device surrounding the extrudate is attached to the outlet or inlet of the pressure reducing device, the surface of the blocking device that goes around the extrudate is made of a flexible sheet, and fluid is press-fitted directly opposite the blocking device. This relates to a method for producing a thermoplastic penta-resin foam, characterized in that the flexible sheet F is pressed onto the surface of the extrudate to close the texture of the extrudate. In the invention, when the extrudate is slid along the surface of the flexible sheet, a sufficient vacuum can be maintained, but the flexible sheet is rubbed by the extrudate and is easily abraded. Therefore, it becomes necessary to replace the flexible sheet within a short period of time. When changing sheets, the vacuum device cannot be used and the continuously possible extrusion process must therefore be interrupted. Therefore, the flexible sea F
Frequent replacement of the parts becomes a new drawback. Therefore, it is necessary to devise ways to extend the life of the flexible sheet.

The following improved invention was created in response to this need: By applying a wire mesh to the surface of a flexible sheet and interposing the wire mesh between the flexible sheet and the extrudate, the entire The company discovered that it was possible to maintain airtightness as well as prevent wear of the seams. The present invention is also based on the discovery that similar effects can be obtained by using metal foil instead of wire mesh.

The improved invention involves extruding the f# melt-plasticized foamable thermal iJ plastic resin composition from a die, passing the extrudate through a vacuum device connected to the die, and further foaming the extrudate in the vacuum device. In the method for producing a foam, an air blocking device surrounding the extrudate is attached to the outlet or inlet of the pressure reducing device, a flexible sheet is placed on the surface of the blocking device facing the extrudate, and a flexible sheet is provided. By drawing a wire mesh or metal foil on the surface of the flexible sheet and pressurizing fluid into the barrier, the flexible sheet is pressed against the surface of the extrudate together with the wire mesh or gold Jsj4 foil, and the flexible sheet is The gist of the present invention is a method for producing a thermoplastic resin foam, which is characterized by having narrow openings.

Further, an invention of an apparatus related to the above invention includes an extruder,
It consists of a device in which a cap and a pressure reducing device are arranged in this order, and the pressure reducing device flit consists of a cylindrical body and an air blocking device attached to at least one end of the cylindrical body, and the blocking device has an annular shape. The annular inner wall surface is made of 1" flexible sheet, and 1lI
The gist of the J-arm sheet is an apparatus for producing thermoplastic resin foam that can be expanded around the center by a fluid that is press-fitted into a block.

Further, the device invention related to the improved invention consists of a device in which an extruder, a mouthpiece, a pressure reducing device, and a device are arranged in this order, and the pressure reducing device 11 includes a cylindrical body and at least one end of the cylindrical body. The air blocking device has an annular shape, and the annular inner wall surface is made of a flexible sheet, and a flexible wire mesh or metal foil is attached on top of the sheet. The gist of the SEED is a thermoplastic resin foam manufacturing device that can be expanded toward the center along with a wire mesh or gold foil by means of a fluid that is press-fitted into a barrier.

The above-mentioned invention method and apparatus will be explained based on the drawings.
It is as follows. FIG. 7 shows one of the methods of this invention.
FIG. 1 is a cross-sectional view showing 1k. Figure 2 is 1, Figure 1 -
It is an enlarged view of the L-line cross section. FIG. 3 is a sectional view of the vicinity of the air blocking device in the method of this invention. FIG. V is a y-IIA#ITm diagram of FIG.

Figure 5 and gb! J/I′i is a sectional view of a flexible sheet used in the present invention.

In Figures 7 to V, / is the base, C is the sizing die, 3 is the connecting plate, yFi pressure reducing device, j is the vacuum suction port, 6#'i foam support, 2-piece pressure reduction adjustment valve, 1f' is a connecting phase plate, ri is an air blocker, /
θ is the extrudate. Among the air blocking devices, the frame is
2-tI′i, flexible sheet, riJ is fluid pressure inlet, //
is wire mesh.

In the apparatus shown in Fig. 7, a sizing die is attached to the tip of the die, and a decompression device is attached beyond that. Since a known extruder can be used as is, illustration is omitted. In the illustrated example, the pressure reducing device is separated and connected to the sizing die via the connecting plate 3, so air is shut off. It is not necessary. However, since the outlet of the vacuum chamber W1 is separated and the extrudate exits as a foam, it must be left open. ◇Therefore, the outlet must be separated and the air must be always shut off. be.

For this purpose, an air shutoff device is provided on the outlet side of the vacuum device WIt.

The inlet of the pressure reducing device is not always connected in an airtight manner to the mouthpiece. After the extrudate leaves the die, it may be temporarily exposed to the atmosphere and then placed in a vacuum chamber. In this case, it is necessary to attach an air blocker to the sunrise side of the decompression equipment & In Figure 7, a flexible sheet octopus is attached to the air blocker, Furthermore, it has a structure in which a fluid pressure inlet J is attached. The frame has an annular shape as a whole, and the extrudate can be passed through it.

The outer shape of the frame is such that it can close the entrance and exit of the pressure reducing device. Further, in the frame body/, the cross section of the ring is U-shaped, and the surface facing the inside of the ring, that is, the inner wall surface of the ring is cut out. The annular inner wall surface is the surface facing the extrudate when the extrudate is passed through the ring. An iJ flexible tacho is attached to this surface. Further, a fluid pressure inlet 3 is provided at a suitable location on the outer surface of the frame 2/. Frame repair/ke,
It may be made of any material as long as it has -I properties, but it is preferably made of gold.

When the side surface of the frame body is fixed in contact with the entrance/exit of the cylindrical body of the pressure reducing device, the entrance/exit communicates with the outside world through an opening surrounded by a flexible sheet octopus.

Therefore, when pressurized fluid, for example pressurized air, is introduced through the fluid pressure inlet 3, the flexible sheet octopus expands and protrudes around the center, thus narrowing the opening. Therefore, when the extrudate 10 is passed through the opening, the inside of the flexible sheet octopus comes into close contact with the surface of the extrudate θ.

If you look at the state at this time in cross section, it looks like Figure 2. That is, the surface of the flexible sheeter 2 is covered with extrudates/
Although it is in close contact with the surface of θ, at the corner of the extrudate/θ, the flexible sheet octopus is folded back to form a double thread. However, the folded flexible sheeter 2#
-i They are so close together that almost no air can escape from the darkness.

As the flexible sheet octopus, various materials such as natural or synthetic rubber or soft synthetic resin can be used. As the synthetic rubber, chloroprene rubber, ethylene propylene rubber, styrene butadiene rubber, urethane rubber, silicone rubber, fluorine rubber, etc. can be used.

As the soft synthetic tung fat, soft vinyl chloride resin is used. be able to.

The cross-sectional shape of the flexible sheet is not limited to that shown in FIGS. 7 and 3. It is also possible to have a shape as shown in FIG.

The method shown in FIGS. 1 and 2 is performed as follows. The melt-plasticized foamable thermoplastic resin composition is extruded from the die and enters the sizing die where it is foamed. In this way, the foamed extrudate/θ
I will enter the decompression device in my second year @decompression device lol! Since the T-gu is equipped with an air barrier at the outlet or inlet, the extrudate/
Air circulation is blocked around θ. Furthermore, air is discharged from the pressure reduction device through the vacuum suction port j, so that the pressure is reduced, and at the same time, the interior of the pressure reduction device is cooled by a mechanism not shown. Therefore, the extrudate /θ is further foamed to increase its volume in the vacuum device, and is cooled in this state to become a highly foamed product and exit the vacuum device W.

The air blocking device y#'i is arranged so as to cover the outlet or inlet of the pressure reducing device, and an opening is formed in the center of the blocking device. The extrudate 10/ri is then passed through the opening into the vacuum device y or allowed to exit the vacuum device wIt. At this time, pressurized fluid is forced into the air blocking device from the fluid pressure inlet 3, so that the readable sheet octopus swells and the opening is narrowed.

The extent to which the flexible sheeter 2 swells can be freely adjusted by adjusting the amount of pressurized fluid injected.

Therefore, the tip of the TIIj flexible sheet clasp can always be brought into close contact with the surface of the extrudate/θ, and air is prevented from flowing in through the opening. In spite of the fact that the extrudate /θ is continuously passed through the depressurizing device y, the depressurized state is well maintained. Therefore, the extrudate/θ can be further foamed in the vacuum neck, and then the extrudate 10 can be cooled to form a good foam.

In the method shown in FIGS. 1 and 2, a flexible sheet octopus is brought into direct contact with the extrudate /θ.

Therefore, it is rubbed by the flexible sheeter JFi extrusion 10. This, as already mentioned, caused wear of the flexible sheet octopus, shortened the lifespan of the flexible sheet, and therefore made it necessary to interrupt the production of the foam in order to replace the flexible sheet. . Another invented method is an improvement on this.

The method of the improved invention is carried out in the same manner as shown in Fig. 1, but Fig. 3 mainly shows the air blocking method or the air blocking device. .

The air blocking device shown in FIG. 3 differs from the air blocking device shown in FIG. 1 in that in FIG. 3, an extra wire mesh or metal foil is provided. To be more specific, in FIG. 3, at the outlet of the decompression device WIy, the cylindrical body and the connecting plate! One end of the wire mesh // is sandwiched between the wire mesh // and the other end of the wire mesh // covers the surface of the flexible sheeter 2 and extends outside the air blocking device.

Money //#i, Like the flexible sheet octopus, it has flexibility, and -J#l' than the flexible sheeter.
lJ is highly flexible. Therefore, wire mesh //iji+
This means that the deformation of the J-challenging sheet octopus can be easily followed. Therefore, as the wire mesh //, one whose metal wire constituting it is thin and has fine mesh is used. Stainless steel wire is suitable as the metal wire.

The wire mesh described above can be replaced with metal foil. As the metal foil, aluminum foil, lead foil, copper foil, etc. can be used. Since the metal foil must be able to easily follow the deformation of the 1" brittle sheet octopus, it is desirable that it be extremely thin and more flexible than the μ1 flexible sheet octopus.

In other words, the flexible sheet octopus is better than metal foil.This is the same as in the case of wire mesh.

The wire mesh//or metal foil is divided into several parts V'i in its cross section. For example, as shown in FIG. 7, it is divided into two parts. In FIG. 7, the wire mesh 777 warp //3 is in contact with the top and bottom surfaces of the extrudate, and the wire mesh //ko and //da are in contact with the left and right sides of the extrudate. It is divided into. Among them, the wire mesh /゛// and //JFi are generally flat, or the wire mesh //, 2 and //41 are bent in a U-shaped cross section, and the adjacent wire mesh /// and //3°
The overlapping parts are made up of the darkness. Since there is an overlapping portion, by adjusting the width of the overlapping portion, even if the cross-sectional shape and size of the extrudate 10 changes, the surface of the extrudate can always be covered with the same wire mesh.

According to the method of the improved invention, in addition to having the same advantages as the method of the specific invention, since a wire mesh or metal foil is interposed between the flexible sheet and the extrudate, there is less wear and tear on the flexible sheet. This has the advantage that manufacturing operations can be carried out efficiently and continuously for a long time. To further explain the latter advantage, since the wire mesh or metal foil has a high density, when the flexible sheet is inflated by fluid pressure, the wire mesh or metal foil can be used to expand the flexible sheet. It follows easily and can thus maintain the extrudate's consistency airtight. Moreover, the wire mesh or gold foil is attached to the pressure reducing device and is only rubbed against the extrudate, but not between the flexible sheet and the flexible sheet, thereby preventing the flexible sheet from being worn out. It will be done. Therefore, according to this method, frequent replacement of the flexible sheet is avoided, and the foam can be manufactured continuously and efficiently.

The method of this invention can be widely used when adding a pre-foamed material to a thermoplastic resin and molding a foam by an extrusion method. That is, as the resin, polystyrene, polyethylene, polyvinyl chloride, polypropylene, etc. can be used, and most other thermoplastic resins can be used. Departure I? ! There are no particular restrictions on the chlorine, and aliphatic hydrocarbons such as ethane, propane, butane, butane, methyl chloride, methylene chloride, ethyl chloride, fluoride, ethyl chloride, chlorodifluoromethane, dichlorodifluoromethane, etc. The method of the present invention can be carried out using halidanized hydrocarbons, bioactive gases such as carbon dioxide, nitrogen, etc. as blowing agents. A heat-melted resin containing such Foaming-1 is a foamable heat-plastic resin composition that is melted and plasticized.

Further, in the method of the present invention, not only a flat die such as a T-die but also a circular die, a rod die, etc. can be used as the die.

Although FIG. 1 shows an example in which a sizing die is interposed between the base / and the pressure reduction table By, the sizing die may be omitted and the pressure reducing device D may be directly connected to the base /. This results in 10 times better foaming of the extrudate.

Further, the apparatus according to the present invention is composed of a known extruder (not shown in FIG. 7), a mouthpiece, and a vacuum-made lid arranged in this order. an air blocking device attached to at least one end of the shaped body;
The blocking device has an annular shape, and the annular inner wall surface is a flexible sheet 5P.
, 2, the gist of which is a flexible sheet 7 and 2, which is capable of expanding toward the center by a fluid pressurized into a blocking device. It is something.

Further, in the arrangement according to the present invention, in the above-mentioned device,
Flexible gold@//or metal foil is attached on top of the flexible sheet, and the flexible sheet can bulge toward the center along with the wire mesh or metal foil by the fluid that is press-fitted into the barrier. This includes equipment for manufacturing thermoplastic resin foams.

According to the device according to the present invention, as described above, a pressure reducing device! Since the flexible sheet octopus alone or together with the wire mesh or metal foil comes into close contact with the extrudate /θ progressing inside the pressure reduction device, the extrudate /θ advances in the decompression device.
The area around θ can be kept airtight. Therefore, the extrudate can be sufficiently foamed within the pressure reducing device, and there is an advantage that four highly foamed foams can be produced continuously and efficiently. In addition, if wire mesh or metal foil is attached,
Because the flexible sheet octopus does not come into direct contact with the extruded material 10K,
Abrasion of the flexible sheet can be prevented. Therefore, the life of the flexible sheet octopus is extended, and extrusion operations can be performed continuously for a long time without replacing the visible sheet octopus 2, which is an advantage.

Next, the details of the method of this invention will be specifically explained with reference to Examples. Hereinafter, when we simply say %, we mean multiple arcs.

Example/-\ Folystyrene was used as the resin, to which butane was added as a foaming agent, talc/% was added as a foam control agent, and extrusion was carried out at a resin temperature of 722°C.

For the cap, the thickness of the tip/, the width of the con n1, 2.5txt
A flat die with a slit was used, and a sizing die was used, and the thickness at the exit of the sizing die was set to /, 21111, and the width was set to JOtm.

A cylindrical body with an inner diameter of θθ and a length of 3 m was used as the pressure reducing device. An air blocking device as shown in Fig. 3 was attached to the exit side of the pressure reducing device. Air blocking device frame/Vi
It was made of iron, and the flexible sheet 2 was made of rubber with a certain thickness. The opening through which the extrudate 10 passes had a width of Owg and a thickness of 30 cm, and the corners were curved to /θR. A stainless steel wire mesh with a thickness of 0.1 m and a 30θ mesh was attached between the sheet octopus and the extrudate 10.

The equipment was carried out as shown in Figure 1, except that an extra wire mesh was attached. First, a foam was obtained without reducing the pressure (without pressurizing air into the air blocker). Take-up speed FiJ j at 9:11 g/min, thickness/j cod,
Width IJtm, foaming ratio? "i72 times.Next, while flowing this foam, from fluid pressure inlet J to o, 1jK
tt/d of air was introduced to inflate the flexible sheet octopus, press the wire mesh // against the extrudate 10, and while increasing the take-up speed, the degree of vacuum in the pressure reducing device was set to JOOmHI. After that, the pressure of the injected air is θ, jK11I/aI
By reducing lIK, it was possible to obtain a foamed product approximately 32 times the size with a thickness of 7 Jvm and a width of 7 Jvm at a take-up speed of 3.1 m and 7 min. Thereafter, the degree of pressure reduction in the pressure reduction device was set to θθM~, and the take-up speed was lowered to 10 m/min. In this way, we were able to obtain a button foam with a thickness of 20 m and a width of 7 J, jm, which was expanded approximately 37 times. Even in the case of 〇, a foam was obtained in a constant stable state,
Even when the degree of vacuum was changed from the j00tg floor to the gθom floor, there was no need to change the air pressure injected from the fluid pressure inlet. Also, the flexible sheet was not worn out at all.

[Brief explanation of the drawing]

FIG. 1 is a side view showing one embodiment of the method of this invention. 2 is an enlarged cross-sectional view taken along the line u--■ in FIG. 7. No. JPiJFi is a sectional view of the vicinity of the air blocking device in another real m gland type according to the method of this invention. FIG. 7 is a sectional view taken along the line IV-IV in FIG. 3. Figure 5 and zb! J is a sectional view of a flexible sheet used in this invention. Explanation of symbols /: Base, C: Sizing end A, Tick pressure reducing device, J: @
4 openings, Ri: Air blocker, Ri/: Frame, Ri 2: Control sheet, Ri 3. Fluid pressure inlet, /δ: extrudate, //: wire mesh. Applicant Sekisui Plastics Co., Ltd. Representative Patent Attorney Masami Sakai Figure F Figure 2 Figure U (A) Figure 10

Claims (1)

[Claims] / A melt-plasticized foamable thermoplastic resin composition is extruded from a die, the extrudate is passed through a pressure reduction device connected to the die, and the extrudate is further removed in the pressure reduction device. In a method of manufacturing a foam by foaming, an air blocking device surrounding the extrudate is attached to the outlet or inlet of a pressure reducing device, a flexible sheet is placed on the surface of the blocking device facing the extrudate, and a flexible sheet is placed inside the blocking device. 1. A method for producing a thermoplastic resin foam, comprising: pressing a flexible sheet onto the surface of an extrudate to close the circumference of the extrudate by pressurizing a fluid into the extrudate. The decompression device consists of a hook-shaped body and an air blocker attached to at least one end of the hook-shaped body, The blocker has an annular shape with an annular inner wall made of a flexible sheet,
A device for manufacturing thermoplastic resin foam, in which a flexible sheet can be expanded toward the center by fluid that is press-fitted into a blocker. J', m extrude the plasticized thermoplastic resin composition capable of foaming from the die, pass the extrudate through a pressure reduction device connected to the die, and further foam the extrudate in the pressure reduction device. , in a method for producing a foam, an air barrier surrounding the extrudate is provided at the outlet or inlet of a pressure reducing device, a flexible sheet is arranged on the surface of the barrier facing the extrudate, and the surface of the flexible sheet is By placing a wire mesh or gold I14 foil on top and pressurizing fluid into the barrier, the flexible sheet is pressed together with the wire mesh or metal foil onto the surface of the extrudate, so as to close around the extrudate. A method for producing a thermoplastic resin foam, characterized by: It consists of a device in which an extruder, a mouthpiece, and a pressure reducing device are arranged in this order, and the pressure reducing device #i consists of a barbed body and an air shut-off device attached to at least one end of the hook-shaped body. The tool has an annular shape with a disc-shaped inner wall surface made of a flexible sheet,
A flexible wire mesh or metal foil wire is attached on top of the sheet, and the flexible sheet has an opening that expands toward the center together with the wire mesh or metal foil by the fluid that is press-fitted directly opposite the shield. Thermoplastic resin foam manufacturing equipment.