JP2001277333A - Extrusion equipment for hydrating foaming resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a foamed resin product having uniform cells small in cell size and high in expansion ratio and excellent in appearance even from a resin high in water content by injecting inert gas in the resin. SOLUTION: A melting process A for kneading a resin while applying feeding force thereto to uniformly melt the resin at a low temperature, a dehydrating/ degassing process B for sucking air from first and second vent parts (c), (e) to remove moisture in the resin, a gas injection process C for injecting inert gas and applying stirring and diffusion action to the resin while suppressing shearing heat generating action to perfectly compatibilize the inert gas and the resin and a cooling and compatibilizing process D for cooling the resin while suppressing shearing heat generating action and preventing the separation of the resin and the inert gas by dispersing and mixing action are successively provided to the cylinder 11 of a unidirectional rotation type twin-screw extruder from the inlet 11i thereof to the outlet 11o thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extrusion equipment for a water-containing foamed resin for producing a foamed product such as a thermoplastic polyester resin having a particularly high water content among thermoplastic resins.

[0002]

2. Description of the Related Art As a conventional method for producing a foamed resin product, a foaming agent is added to a raw material of a resin, mixed and supplied to an extruder, heated to a temperature higher than the decomposition temperature of the foaming agent, melted, and melted at a high pressure. There is a chemical foaming method of obtaining foamed products by suppressing foaming in the cylinder by holding it underneath and releasing the pressure at the exit of the die.
29392 and the like. However, in this method, a high-magnification product cannot be obtained, and even if the amount of the foaming agent is increased, gas is released from the hopper or the gas cannot be retained in the molten resin, and is released from the surface, and the product becomes rough. Cause problems such as

A physical foaming method for injecting an organic compound such as butane and pentane into a resin of an extruder in a high-pressure liquid state, mixing and dispersing the resin into a resin, and extruding the resin from a die to form a foamed product. There is. In this method, a high-magnification product is easily obtained because the organic compound has high affinity and solubility for the resin. However, this organic compound is highly flammable and explosive, and is dangerous. Therefore, the extruder is required to have explosion-proof specifications to increase safety, increase equipment cost, and require careful attention to operation.

[0004]

Therefore, in recent years, a fluorocarbon gas has been injected into the resin in some cases. However, due to problems such as ozone destruction, an inert gas such as carbon dioxide gas or nitrogen gas is used. For example, see Japanese Patent No. 295580
No. 9 has been proposed.

However, inert gases such as carbon dioxide gas and nitrogen gas are inferior in affinity, diffusivity and solubility as compared with the above-mentioned organic compounds and chlorofluorocarbon-based gases, so that the bubble diameter of the foamed cells tends to increase. In addition, there is a problem that bubbles are likely to be non-uniform.

[0006] For example, thermoplastic polyester resin (PET) is a resin having high water content, low melt viscosity, and difficult to be a foamed product.
It has been said that a hydrolysis reaction causes a decrease in viscosity and a decrease in physical properties, so that fine foam cells cannot be maintained, and it is extremely difficult to obtain a good foam product.

The present invention relates to a highly water-containing resin such as a PET resin or a Niro resin, and a foaming agent that foams in the resin;
Injects an inert gas with high safety and low affinity, diffusivity and solubility into the resin of the extruder without using organic compounds such as butane and pentane. It is an object of the present invention to provide an extrusion equipment for a hydrous foamed resin, which can uniformly disperse the water and obtain a foamed product having an excellent appearance.

[0008]

According to one aspect of the present invention, there is provided an extruder for injecting an inert gas into a resin while being propelled by two screws,
In a water-containing foamed resin extruder equipped with a molding die for shaping the resin supplied from the extruder, the resin is kneaded while applying a conveying force to the resin in order from the inlet to the outlet of the cylinder of the extruder. Melting process to uniformly melt the resin in a low temperature state, dehydration and degassing process to remove moisture in the resin by suctioning from the vent port, and stirring and diffusing while injecting inert gas to suppress shear heating And a cooling compatibilizing step of cooling and suppressing the shear heat generation to prevent separation of the resin and the inert gas by the dispersive mixing action. It was done.

According to the above construction, in the dehydration / degassing step after the initial melting step, the water content in the resin is quickly removed from the vent port at a low temperature to prevent the resin viscosity from lowering. No inert gas is injected into the resin in the gas injection step and stirred and diffused to achieve complete compatibilization of the inert gas and the resin. Separation of the inert gas can be prevented, and even if the affinity gas, the diffusivity, and the solubility of the inert gas are inferior, the foam cells are small and air bubbles can be uniformly dispersed in the resin.
Further, a foamed product having an excellent appearance can be obtained.

Further, the invention according to claim 2 is characterized in that the gas injection step is provided with a gas injection nozzle into which an inert gas of a predetermined pressure is injected, and the stirring / diffusion operation with a small propulsion force while suppressing the shear heat generation effect. And a diffusion mixing section in which a mixing segment and a mixing segment are attached to the axis of the screw to provide complete compatibility between the inert gas and the resin.

According to the above configuration, the kneading disk and the mixing segment can effectively stir and diffuse the inert gas into the resin while suppressing the heat generation due to the shearing, thereby achieving perfect compatibilization.

Further, according to the third aspect of the present invention, in the above structure, a cooling structure is provided between the extruder and the die, and the separation of the resin and the gas is prevented by the dispersing and mixing action due to the engagement of the delivery gear. And a gear pump for maintaining the resin pressure at the extruder outlet at a low pressure.

[0013] According to the above construction, the heat generation of the resin due to the resin back pressure due to the resin pressure at the tip of the screw of the extruder is reduced, and while the heating of the cylinder and the screw is suppressed, the engagement of the delivery gear and the fixed discharge effect are achieved. The outlet pressure can be kept constant by eliminating the influence of the cylinder outlet pressure,
High extrusion stability can be ensured. And
Due to the dispersion and mixing effect of the engagement of the delivery gears, the cooling compatibilizing function of the extruder is shared with the inside of the cylinder by forced cooling while preventing separation of the inert gas and the resin, thereby achieving compactness.

A fourth aspect of the present invention provides a co-rotating extruder for producing a foamed resin by injecting an inert gas into the resin during propulsion by two screws arranged in a cylinder. In a water-containing foamed resin extruder equipped with a molding die for molding the resin supplied from the extruder, a lead flight mounted on a screw shaft in order from an inlet to an outlet of a cylinder of the extruder. A transport unit that kneads and melts the resin uniformly in a low temperature state while applying a transport force to the resin by the block, and a plurality of sets of kneading discs mounted on the screw shaft are combined to weaken the resin A melting process having a kneading melting section that melts the resin while preventing shear heat generation and prevents backflow of the inert gas, and is transported by a lead flight block. A first vent port for sucking and dehydrating moisture from the molten resin to be formed, a kneading seal block for applying a weak resistance to the molten resin by a group of kneading disks downstream of the first vent port to form a resin seal, A dewatering / degassing step having a second vent port for sucking and dehydrating moisture from the molten resin whose surface has been renewed while shutting off the first vent port by a kneading seal block, and injecting an inert gas into the molten resin. A gas injection nozzle was provided, and a kneading disk and a mixing segment were attached to the screw shaft to provide a stirring-diffusion effect with a small propulsion force while suppressing the shear heating effect and to achieve complete compatibility between the inert gas and the resin. A gas injection process having a diffusion mixing section, a lead flight block having a cooling means and providing a propulsion to the resin, and a weak propulsion A cooling compatibilizing step having a compatibilizing holding part mounted on a screw shaft, wherein kneading disks that prevent separation of resin and inert gas by dispersing and mixing while suppressing shear heat generation are alternately combined. A gear pump provided with a cooling structure between the extruder and the die to maintain a low resin pressure at the outlet of the extruder while preventing separation of the resin and the gas by a dispersive mixing action due to engagement of a delivery gear. Is provided.

According to the above construction, the resin is melted at a low temperature while suppressing shear heat generation by the combination of the lead flight block and the kneading disk in the melting step, and the molten resin is formed by the kneading disk group in the dewatering / deaeration step. By imparting a weak resistance, the dewatering and degassing effect from the second vent port is improved, and water is quickly removed to prevent a decrease in the viscosity of the resin. Then, in the gas injection step, an inert gas having no explosive property is injected from the gas injection nozzle, and the inert gas is effectively agitated and diffused into the resin while suppressing the shearing heat generation effect by the kneading disk and the mixing segment. Complete compatibilization can be achieved. Further, in the cooling compatibilizing step, the separation of the resin and the inert gas is prevented by the dispersion mixing action while suppressing the shear heat generation by the lead flight block and the kneading disk group. In addition, the gear pump reduces the shear heat generated by the resin back pressure flow due to the resin pressure at the screw tip of the extruder, while suppressing the heat generated by the cylinder and screw. The outlet pressure can be kept constant without any influence, and high extrusion stability can be ensured. By dispersing and mixing effects due to meshing of the delivery gears, the cooling compatibilizing function of the extruder is shared with the inside of the cylinder by forced cooling while preventing separation of the inert gas and the resin, thereby achieving compactness. . Thereby, even if the inert gas is inferior in affinity, diffusivity, and solubility, the foam cells are fine and bubbles can be uniformly dispersed in the resin, and a foamed product having an excellent appearance can be obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, an embodiment of an extrusion equipment for hydrous foamed resin according to the present invention will be described with reference to FIGS.

As shown in FIG. 1, this foaming resin extrusion equipment is for producing, for example, a foaming resin sheet S. In order from an upstream side, a twin-screw extruder 1, a gear pump 2, a sheet forming die 3, a cooling A mandrel 4, a take-up machine 5, and a take-up machine 6 are arranged. The twin-screw extruder 1 is a co-rotating type completely meshing type. As shown in FIG. 2, the shafts 12a of two screws 12 are arranged in a cylinder 11 in parallel with each other, and an extrusion driving device (shown in FIG. 2), the screw shaft 12 is driven to rotate in the same direction via the reduction distribution gear box 8. While the resin material supplied from the material supply feeder 9 is kneaded and melted, an inert gas, for example, carbon dioxide gas is supplied from the foaming gas supply device 10 to the cylinder 1.
1, kneaded, compatibilized, and sent out. Further, the resin is extruded from the sheet forming die 3 via the gear pump 2 to be foamed and formed into a sheet shape.
After being expanded by the cooling mandrel 4 to cool the inner and outer surfaces, it is taken up by the take-up machine 6 via the take-up machine 5.

As shown in FIG. 2, in the twin-screw extruder 1, the total length L of the cylinder 11 is set to be 30 times or more the cylinder diameter (short diameter) D. From the entrance 11i to the exit 11o,
A melting step A having a conveying section a and a kneading melting section b, a first vent section c, a mixing seal block d, and a second
A dehydration / deaeration step b having a vent portion e, and a diffusion mixing portion f
And a cooling compatibilizing step D having a compatibilizing holding part g.

(Melting Step A) Conveying Section a in Melting Step A
As shown in FIGS. 3A and 3B, a lead flight block 21 having two spiral ridges 21a is connected to a shaft 12a.
To form a completely meshing type screw 12. In addition, this lead flight block 21
The first vent portion c, the second vent portion e, and the compatibilizing holding portion g are also provided. Also, the kneading and melting part b is the
(A) As shown in (b), a plurality of sets of kneading disks 22 mounted on the screw shaft 12a are combined to apply a weak conveying force to the resin and to knead and melt the resin while suppressing shear heat generation. In addition, the transport portion a and the first vent portion c, which are at substantially atmospheric pressure, are shut off by sealing the molten resin.

The lead flight block 21 is different from the lead flight screw of an ordinary single screw extruder in that
It is characterized by a large transport promoting action of the resin raw material, a large kneading and dispersing action, and a large screw surface area.Since it is a co-rotating type, the reaction force of the screw is not applied to the cylinder as compared with the counter-rotating type, In addition, the structure is such that the resin is hardly moved into the minute space of the screw by moving spirally in a cocoon shape. The fully meshing and co-rotating twin-screw extruder ensures that the transport of resin material is promoted, the kneading and dispersing action at low temperatures is high, and the inert gas and the resin make use of the large screw surface area. Complete compatibilization by diffusion mixing and low temperature cooling using a long screw cylinder are indispensable for obtaining good resin products.

The shaft 12a of the screw 12 of the kneading and melting portion b
3 (a) and 3 (b)
As shown in the figure, a plurality of sets (four sets in the figure) assembled so as to have a weak propulsion action by being shifted by a predetermined phase difference (45 degrees in the figure) in the same direction as the lead flight block 21.
And a disk group (or a plurality of disk groups) in which five substantially elliptical disk plates 22a are combined so as to have a weak reverse propulsion action with a predetermined reverse phase difference (45 ° in the figure) on the downstream side thereof. (One set in the figure). As a result, low-temperature extrusion is enabled by suppressing the shear heat generation effect while melting the resin. In addition, in order to suppress shear heat generation while measuring the kneading and melting of the resin and the resin seal,
It is preferable to combine a disk group having a weak kneading action, and the length L1 of the kneading and melting portion b is a cylinder diameter (short diameter) D × 3 to
It is set to about 4. Depending on the characteristics of the resin and the allowable temperature, a disk group having a phase difference of 90 ° without propelling action,
A group of disks having opposite phases may be increased.

(Venting Step B) The kneading seal block d in the venting step B hermetically seals off the space between the first vent section c and the second vent section e having the lead flight block 21 and kneads the resin to form a resin film. And the function of enhancing the dewatering / deaeration effect in the second vent portion e is performed. For this reason, a plurality of sets (two sets in the figure) of a group of disks assembled so as to have a weak propulsion action with a predetermined phase difference (45 ° in the figure) shifted in the same direction as the lead flight block 21 are attached, and the kneading seal block is attached. The sealing effect and the kneading cost are exhibited with a small propulsion force while suppressing the shear heat generation effect of the resin in d. In addition, a vacuum pump 1 is connected to the first vent c and the second vent e through piping.
5 connected, high vacuum (less than 5 torr, at least 10 torr)
Below). Here, the case of two vents has been described, but it may be increased or decreased depending on the resin properties and the water content. In particular, in the case of PET resin, a hydrolysis reaction occurs. The distance between the first vent portion c and the second vent portion e is a cylinder diameter (short diameter) D × 6 to
About 8 is good.

(Gas Injecting Step C) In the diffusion mixing section f in the gas injecting step C, a gas injection nozzle 14 for injecting an inert gas of a predetermined pressure into the cylinder 11 is provided. The loading disk 22 and the mixing segment 23 are mounted so as to impart a stirring and diffusing action with a small propulsive force while suppressing the shear heat generating action of the resin, thereby achieving complete compatibility between the inert gas and the resin.

Kneading disk 22 of diffusion mixing section f
In the same manner as the kneading / melting portion b upstream kneading disk 22, a plurality of (five in the figure) disk plates 22a are combined with a phase difference of 45 ° in the same direction as the lead flight block 21 to provide a weak propulsion effect. It is configured to have. Further, the mixing segment 23 arranged on the downstream side to face the gas injection nozzle 14 has a structure shown in FIG.
(A) As shown in (b), a mixing disk 23a having approximately 12 to 16 kneading teeth 23b protruding at regular intervals in a circumferential direction of a ring-shaped main body 23a and a spacer ring 2
3c is constituted by a plurality of (about 4 to 10) diffusion / mixing units alternately combined. in this way,
Kneading disc 22 and mixing segment 23
By reducing the shear heating effect, by increasing the surface area of the screw, further reducing the propulsion force and increasing the residence time of the resin, by combining
The inert gas is uniformly dissolved in the resin by enhancing the stirring / diffusion effect, thereby realizing complete compatibility between the molten resin and the inert gas. Here, the length L2 of the cylinder 11 in the gas injection process C
Is desirably about 2 to 3 cylinder bores (short diameter) D.

In this case, the kneading disk 22 is used.
And the mixing segment 23 are combined, but depending on the resin characteristics, only one of them may be used, or another block or a combination of blocks having a small shearing heat action and a small propulsive force and a high stirring action may be used.

(Cooling Compatibilizing Step D) In the cooling compatibilizing step D, the molten resin and the inert gas are in a completely compatibilized state. The dispersing / mixing unit 24 combining a plurality of (five in the figure) kneading discs 22a of the kneading discs 22 having different thicknesses is arranged at predetermined intervals at two intermediate portions while maintaining the compatibilization while giving propulsive force. Section g is configured. Thereby, separation of the inert gas from the molten resin is prevented by the dispersion mixing function while suppressing and reducing the shear heat generation function. With this, even if the carbon dioxide gas is inferior in affinity, diffusivity, and solubility, the bubble diameter is small at high magnification, and the bubbles are uniformly dispersed in the resin.
A foam product having an excellent appearance can be obtained.

(Gear pump 2) As shown in FIGS. 6 and 7, the gear pump 2 is connected to the cylinder outlet 11o via a conduit, and in order to keep the inlet pressure Pg1 constant, the rotation speed of the screw 12 of the twin screw extruder 1 is changed. Transmission gear 2 of gear pump 2
The rotation speeds of a and 2b are controlled, and the resin pressure at the tip of the screw 12 is maintained at a low pressure. Thereby, heat generation due to the back pressure flow of the resin is reduced, and heat generation of the cylinder 11 and the screw 12 can be effectively suppressed. Further, by the dispersing, mixing and quantitative transfer functions of the resin due to the engagement of the delivery gears 2a and 2b of the gear pump 2, the inlet pressure Pg1 and the outlet pressure Pg2 of the gear pump 2 are cut off, and the outlet pressure Pg2 is kept constant. The resin is sent to the die 3.
Further, the dispersing and mixing of the resin due to the engagement of the delivery gears 2a and 2b prevents separation of the resin and the inert gas.

The casing 31 of the gear pump 2 includes a pump chamber 32 for accommodating the delivery gears 2a and 2b, a main body 31a having an inlet 33a and an outlet 33b connected thereto, and a casing 31 for the delivery gears 2a and 2b. The cooling structure includes side covers 31b and 31c that support the shaft portion, and cooling holes 34a, 34b and 34c for circulating cooling oil as a cooling medium are formed in the main body 31a and the side covers 31b and 31c, respectively. ing. Note that cooling holes 34d may be formed in the shafts of the delivery gears 2a and 2b.

The resin introduced from the inlet 33a into the pump chamber 32 is connected to the delivery gears 2a and 2b which mesh with each other.
And is fixedly transferred to the outlet 33b, and is forcibly cooled by the cooling oil sent to the cooling holes 34a, 34b, 34c and maintained at a predetermined temperature.
For most of the foamed resin, cooling from the cooling holes 34a, 34b, 34c formed in the casing 31 is sufficient, but if insufficient, the cooling formed on the shafts of the delivery gears 2a, 2b. Cooling may be performed from the hole 34d.

As described above, since the gear pump 2 having the forced cooling structure is employed, heat generation is suppressed while the resin back pressure is kept low, and separation of the inert gas and the resin is prevented while enhancing extrusion stability. Rather, an excellent cooling compatibilizing effect is realized by effective cooling. Further, by adopting the gear pump 2, functions such as reduction of back pressure, suppression of heat generation, and suppression of separation of inert gas at the outlet 11o of the cylinder 11 necessary for extrusion of the foamed resin can be enhanced. The length L can be shortened, and the twin-screw extruder 1 can be made compact.

Example A PET foamed resin sheet was extruded using the twin-screw extruder having the above configuration. This twin-screw extruder is equipped with a fixed feeder and has a screw diameter of 5 mm.
After venting suction at two intermediate portions of the cylinder with a 7 mm screw / cylinder length of L / D = 40 in the same direction, a carbon dioxide gas was supplied into the resin to obtain a foamed product by a die. The resin material is water-containing P containing about 0.4% water.
With ET resin, the main operating conditions are as follows.

Screw rotation speed: 70 rpm, gear pump rotation speed: 5 rpm, extrusion rate: 75 N / H, cylinder temperature 260-280 ° C., gear pump temperature: 260 ° C., first
Vent section vacuum: 10 Torr, second vent section vacuum: 5 To
rr, supply amount of carbon dioxide: 0.2 N / min, supply pressure of carbon dioxide: 20 MPa.

Further, a molded foam sheet (IV: 0.85)
Was composed of fine cells having a thickness of 1.1 mm and a magnification of 1.7, and was able to be molded stably with good appearance. According to the above-described embodiment, the first and second vent portions c and e can be effectively utilized by utilizing the transport propulsion action, the kneading dispersion action, and the large screw area, which are the basic characteristics of the co-rotating twin-screw extruder 1. Degassing and dehydration, and furthermore, it is possible to reliably prevent the inert gas supplied into the molten resin from the gas injection nozzle 14 from being released at the intermediate portion of the cylinder 11 and completely compatibilize the molten resin and the inert gas, It is possible to produce a good foamed product having a small cell diameter, high magnification, and uniformly dispersed cells.

In addition, by using, for example, carbon dioxide as an inert gas to be used, the gas is injected into the cylinder 11 in a state of being vaporized at a constant pressure from the gas cylinder, so that the handling is safe and the safety is high.

Further, in the melting step A, the resin is melted while suppressing shear heat generation by the combination of the lead flight block 21 of the kneading and melting portion b and the kneading disk 22 of the kneading and melting portion b. Next, in the venting step B, the first vent portion c and the second vent portion e are cut off by the kneading seal block d having a weak propulsion action by shifting the predetermined phase difference in the same direction as the lead flight block 21 and the second vent portion e. The deaeration effect in the vent portion e is enhanced, and the sealing effect and the kneading effect can be exhibited with a small propulsion force while suppressing the shear heat generation effect of the resin. Further, in the resin, an inert gas is injected into the resin from the gas injection nozzle 14 in the gas injection step C, so that the kneading disk 22 and the mixing segment 23 suppress the shear heat generation effect, thereby reducing the inert gas in the resin. Completely compatibilized by stirring and diffusing. Further, in the cooling compatibilizing step D, the lead flight block 21 and the kneading disk 22
This prevents the separation of resin and inert gas by the dispersing and mixing action while suppressing the shear heat generation, so that even if the inert gas has poor affinity, diffusibility, and solubility, the bubble diameter is small at high magnification. As a result, air bubbles are uniformly dispersed in the resin, and a foamed product having an excellent appearance can be obtained.

In the above embodiment, the inert gas supplied into the molten resin is carbon dioxide gas, but nitrogen gas or argon gas can also be used.

[0037]

As described above, according to the first aspect of the present invention, in the dewatering / degassing step after the initial melting step, the water in the resin is quickly removed from the vent port at a low temperature. Inert gas that does not explode is injected into the resin in the gas injection process to stir and diffuse, and complete insolubilization of the inert gas and the resin is performed. Since the dispersing and mixing action is imparted to the resin, separation of the resin and the inert gas can be prevented, and even if the inert gas has poor affinity, diffusivity, and solubility, the foam cells are small and bubbles are generated in the resin. A foam product that can be uniformly dispersed and has an excellent appearance can be obtained.

According to the second aspect of the present invention, the kneading disk and the mixing segment provide:
The inert gas can be effectively agitated and diffused into the resin while suppressing the heat generation due to the shearing, thereby achieving complete compatibilization.

Further, according to the third aspect of the present invention, the heat generation of the resin due to the resin back pressure due to the resin pressure at the tip of the screw of the extruder is reduced, and while the heating of the cylinder and the screw is suppressed, the engagement of the delivery gear with the screw is reduced. Due to the constant discharge effect, the pressure at the cylinder outlet can be kept constant without the influence of the pressure at the outlet, and high extrusion stability can be ensured. By dispersing and mixing effects due to meshing of the delivery gears, the cooling compatibilizing function of the extruder is shared with the inside of the cylinder by forced cooling while preventing separation of the inert gas and the resin, thereby achieving compactness. .

According to the fourth aspect of the present invention, the resin is melted at a low temperature while suppressing shear heat generation by the combination of the lead flight block and the kneading disk in the melting step, and the kneading disk is melted in the dewatering / deaeration step. The group imparts a low resistance to the molten resin to improve the dewatering and degassing effect from the second vent port, and quickly removes water to prevent a decrease in the viscosity of the resin. Then, in the gas injection step, an inert gas having no explosive property is injected from the gas injection nozzle, and the inert gas is effectively agitated and diffused into the resin while suppressing the shearing heat generation effect by the kneading disk and the mixing segment. Complete compatibilization can be achieved.
Further, in the cooling compatibilizing step, the separation of the resin and the inert gas is prevented by the dispersion mixing action while suppressing the shear heat generation by the lead flight block and the kneading disk group. In addition, the gear pump reduces shear heat generation due to resin back pressure flow due to resin pressure at the screw tip of the extruder,
By suppressing the heat generated by the cylinder and screw, the engagement of the delivery gear and the constant discharge effect eliminates the effect of the cylinder outlet pressure, thereby keeping the outlet pressure constant and ensuring high extrusion stability. it can. And, due to the dispersion mixing effect due to the engagement of the sending gear,
By making the cooling compatibilizing function of the extruder shared with the inside of the cylinder by forced cooling while preventing separation of the inert gas and the resin, compactness can be achieved. Thereby, even if the inert gas is inferior in affinity, diffusivity, and solubility, the foam cells are fine and bubbles can be uniformly dispersed in the resin, and a foamed product having an excellent appearance can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a foamed resin extrusion facility according to the present invention.

FIG. 2 is a cutaway perspective view of a cylinder showing the twin-screw extruder.

FIGS. 3A and 3B show a lead flight block of the twin-screw extruder, wherein FIG. 3A is a side view and FIG. 3B is a cross-sectional view.

FIGS. 4A and 4B show a kneading disk of the twin-screw extruder, wherein FIG. 4A is a side view and FIG. 4B is a cross-sectional view.

FIGS. 5A and 5B show a mixing segment of the twin-screw extruder, wherein FIG. 5A is a side view and FIG. 5B is a cross-sectional view.

FIG. 6 is a side sectional view showing the gear pump.

FIG. 7 is a perspective view showing the gear pump.

[Explanation of symbols]

 A melting step B dehydration / deaeration step C gas injection step D cooling compatibilizing step a transport section b kneading and melting section c first vent section d mixing seal block e second vent section f diffusion mixing section g compatibilization holding section 1 2 Shaft extruder 9 Raw material supply feeder 10 Foaming gas supply device 11 Cylinder 12 Screw 12a Screw shaft 14 Gas inlet 21 Lead flight block 22 Kneading disc 23 Mixing segment

Continuing from the front page (72) Inventor Ken Kimura 1-7-89 Minami Kohoku, Suminoe-ku, Osaka-shi, Osaka F-term in Hitachi Zosen Corporation 4F207 AA24 AA29 KA01 KA11 KF02 KF12 KJ06 KK04 KK13 KK41 KK48 KL05

Claims (4)

[Claims] An extruder for injecting an inert gas into a resin while being propelled by two screws, and a molding die for shaping the resin supplied from the extruder. In the extrusion equipment, a melting step of kneading while applying a conveying force to the resin and melting the resin uniformly in a low temperature state in order from the inlet to the outlet of the cylinder of the extruder; A dewatering / degassing process to remove the moisture of the gas; a gas injecting process to inject the inert gas to suppress the shear heat generation effect and to impart a stirring / diffusion effect to completely compatibilize the inert gas and the resin; An extruder for a water-containing foamed resin, comprising: a cooling compatibilizing step of cooling while suppressing heat generation and preventing separation of the resin and the inert gas by a dispersion mixing action. 2. A gas injection step for injecting an inert gas of a predetermined pressure in a gas injection step, and a stirring and diffusing action is imparted with a small propulsion force while suppressing a shearing heat action, thereby forming an inert gas and a resin. 2. A kneading disk for achieving complete compatibilization and a diffusion mixing section provided with a mixing segment mounted on a screw shaft.
The extrusion equipment for water-containing foamed resin according to the above. 3. A cooling structure is provided between the extruder and the die,
A water pump according to claim 1 or 2, further comprising a gear pump for keeping the resin pressure at the outlet of the extruder at a low pressure while preventing separation of the resin and the gas by a dispersive mixing action caused by meshing of the delivery gears. Extrusion equipment for foamed resin. 4. A co-rotating extruder for producing a foamed resin by injecting an inert gas into the resin while being propelled by two screws arranged in parallel in a cylinder, and supplied from the extruder. In the extrusion equipment for a hydrous foamed resin equipped with a molding die for molding the resin, in order from the inlet to the outlet of the cylinder of the extruder, a conveying force is applied to the resin by a lead flight block mounted on a screw shaft. Combination of multiple transport units that knead while applying and melts the resin uniformly at low temperature, and multiple sets of kneading discs mounted on the screw shaft, apply a weak transport force to the resin and suppress shear heat generation A melting step having a kneading and melting section for melting the resin while preventing the backflow of the inert gas, and removing water from the molten resin conveyed by the lead flight block. A first vent port for drawing and dewatering, a kneading seal block that forms a resin seal by applying a weak resistance to the molten resin by a kneading disk group downstream of the first vent port, and a first vent formed by the kneading seal block. A dewatering / degassing step having a second vent port for sucking and dehydrating moisture from the molten resin whose surface has been renewed while shutting off the molten resin surface, and a gas injection nozzle for injecting an inert gas into the molten resin, and A gas injection with a diffusion mixing section in which a kneading disk and a mixing segment are attached to the axis of a screw to provide a stirring and diffusing action with a small propulsion force while suppressing the shear heating effect and to achieve complete compatibility between the inert gas and the resin. Process and a lead flight block that has cooling means and gives propulsion to the resin. A cooling compatibilizing step having a compatibilizing holding section mounted on a screw shaft in which resin and a kneading disk group for preventing separation of an inert gas by a dispersing action is provided alternately, and the extruder and A gear pump is provided between the die and the cooling pump to keep the resin pressure at the outlet of the extruder low while preventing the resin and gas from being separated by the dispersive mixing action by the engagement of the delivery gears. Extrusion equipment for hydrous foamed resin.