JP2000141448A - Foamed sheet and film molding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a foamed sheet which is free from the generation of a trouble such as a curtain wall phenomenon and does not show a low magnification trend due to the dissipation of a foaming gas as well as a film molding device. SOLUTION: An extrusion die flow path A is formed inside an extrusion die 11 and the tip of the extrusion die flow path A is opened to the outside, and further, the extrusion die 11 is arranged in such a way that the tip of the extrusion die flow path A is set in close proximity to the outer peripheral face 13a of a cooling roll 13, leaving a gap between the tip and the outer peripheral face 13a. At the same time, a flow path between the die 11 and the roll 13 following the extrusion die flow path A is formed between the end part 24a (24b) of the extrusion die 11 and the cooling roll 13. Further the surface of a foam 16 discharged from the flow path between the die 11 and the roll 13 is cooled to form a skin layer 52a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a foamed sheet using a polypropylene resin as a raw material, which is excellent in surface smoothness (hereinafter, referred to as surface smoothness) and cell independence (hereinafter, referred to as closed cell). The present invention relates to a molding device for forming a foamed film. More specifically, the present invention provides a foam sheet in which an outlet portion of a molten resin in an extrusion die is disposed to face a cooling roll, and a resin passage having a large gap with the cooling roll surface is formed near the outlet portion. The present invention relates to a film forming apparatus.

[0002]

2. Description of the Related Art Generally, a foamed sheet and a foamed film of a polypropylene resin having an expansion ratio of about 1.5 to 5 times are lightweight and have a moderate buffering property. For this reason, the foamed sheet and the film are used as a core material or a building material for interior materials for automobiles, and are further subjected to secondary processing to form a box or a storage case.
Widely used for cutting materials, stationery, tableware, etc. Conventionally, a flat die called a T-die has been widely used for extrusion molding of a foamed sheet and a foamed film. Below, Figure 1
The structure and operation of the die 60 will be described with reference to FIGS. In these figures, a conduit 61 is formed on the upper part of the die 60, and communicates with the conduit 61 so that the manifold portion 62, the pre-land portion 63, and the lip land portion 6 are connected.
4 are formed respectively. As shown in FIG. 17, the dimension of the lower part of the pre-land portion 63 is suddenly reduced in the thickness direction, and the lip land portion 64 subsequent thereto has the minimum flow path thickness.

The operation of the conventional die 60 having the above configuration will be described below. First, when a molten resin is supplied to the conduit 61 from an extruder (not shown), the molten resin flows in the width direction of the die 60 in the manifold 62. Next, the molten resin is supplied from the manifold 62 to the pre-land 6.
3. The foam 16 is discharged from the die outlet 65 through the lip land portion 62. The pressure of the molten resin inside the die 60 is maximum at the extruder tip (not shown) corresponding to the inlet, and gradually decreases toward the downstream with the conduit 61 and the manifold 62. The internal pressure of 60 decreases to atmospheric pressure.
In this case, the ratio of the maximum flow channel thickness of the pre-land portion 63 to the minimum flow channel thickness of the lip land portion 64 is only several times, so that the pressure gradient is relatively gentle. Such a die 6
When performing foam sheet molding by the extrusion foaming method using 0,
There are two problems in obtaining a flat molded product such as a foamed sheet or film having an expansion ratio of 3 times or more. Here, the expansion ratio is a value obtained by dividing the density of the resin, for example, the polypropylene resin, by the apparent density of the foam,
Indicates a measure of lightness.

The first problem is that since the molten resin expands isotropically immediately after flowing out of the die outlet 65, as shown in FIG. Hereinafter, this phenomenon will be referred to as a curtain wall phenomenon or a corrugation phenomenon), and it is difficult to obtain a uniform molded product. The second problem is that when the molten resin flows inside the die 60 or flows out from the die outlet 65, the foaming gas is dissipated, and the foaming ratio of the foam 16 is reduced. This problem will be described with reference to FIG. 19 which is a graph showing the resin pressure along the flow direction. As can be seen from this graph, in the conventional die 60, since the length of the lip land portion 64 is long and the pressure drop in the flow direction is gentle, the resin pressure is equal to or less than the foaming pressure. Therefore, die 6
Air bubbles are generated inside the gas flow path 0, and a bubble breaking phenomenon occurs due to shearing with the flow path wall surface, and the foamed gas is dissipated. Further, after flowing out of the die outlet 65, the resin in the semi-molten state is rapidly reduced in pressure and expanded, so that the gas in the molten resin foams and dissipates, and the above-described problem occurs. In order to solve this problem, the following three countermeasures have been mainly attempted.

The first countermeasure is a technique of performing roll forming and immersion in water on a foamed sheet extruded before bubble breakage occurs. For example, JP-A-7-276472 or JP-A-9-109234 discloses the technique. No. 6,009,036. The second countermeasure is to set the tip of the extrusion die 60 to 5 to 3
This is a technique of mounting a cooling plate which is opened at an angle of 5 ° and whose temperature is adjusted to 20 to 100 ° C., and cools an extruded foam sheet. For example, JP-A-9-216273 and JP-A-8-142156 Etc. A third countermeasure is a technique for bringing the tip of the die 60 closer to the cooling roll to improve the adhesion of the molten resin to the cooling roll.
No. 7 discloses this.

[0006] However, in the first countermeasure, since an air gap exists between the tip of the extrusion die and the cooling roll, a curtain wall phenomenon is easily generated between the air gap and the foaming gas is dissipated to increase the foaming ratio. There was a risk of lowering. In the second countermeasure, when the molten resin expands at the enlarged portion at the tip of the die, a bubble breaking phenomenon occurs due to shearing, and the foaming gas may be dissipated to lower the foaming ratio. In the third countermeasure, it is difficult to overcome the above two problems because the flow path formed inside the extrusion die is not in a shape suitable for foam molding.

[0007]

DISCLOSURE OF THE INVENTION The present invention has solved the above-mentioned problems, and has no curtain wall phenomenon.
An object of the present invention is to provide a foamed sheet and a film forming apparatus in which a foaming gas does not dissipate and a foaming ratio does not decrease.

[0008]

Aspect 1) In order to achieve the above object, a foam sheet and a film forming apparatus according to the present invention form an extrusion die flow path inside an extrusion die, and the extrusion die flow path is formed. The extrusion die is disposed in a state where the tip is close to the outer peripheral surface of the cooling roll with a gap therebetween, and a die / roll between the end of the extrusion die and the cooling roll, which follows the extrusion die flow path. An inter-channel is formed. The gap is preferably such that the end of the extrusion die channel does not contact the cooling roll, and is appropriately selected according to the type of the foam. The end of the extrusion die is preferably, for example, a movable block formed integrally with the extrusion die or formed separately from the extrusion die. According to the above-described molding apparatus, a resin flow path when the molten resin foams is formed by the die-roll flow path formed between the outer peripheral surface of the cooling roll and the end of the extrusion die. That is, the molten resin supplied to the extrusion die flow path is foamed while being restricted in the die-to-roll flow path, so that problems such as the conventional curtain wall phenomenon are eliminated.

Aspect 2) In another aspect of the present invention, the thickness of the die-to-roll flow path is set such that the thickness of the extrusion die flow path extends from the grounding portion where the extension of the extrusion die flow path intersects the outer peripheral surface of the cooling roll. It is formed larger than the channel width of the die channel. According to the molding apparatus, the upstream side of the die-roll flow path forms a grounding point with respect to the cooling roll, and this grounding point is minute along the generatrix direction (direction along the outer peripheral surface) of the cooling roll. The structure extends through the gap to suppress air from being caught downstream. A die extending in the rotation direction of the cooling roll between the extrusion die and the cooling roll downstream of the contact point.
A flow path between the rolls is formed, where the resin foams, the foaming in the width direction is restrained by side flow path walls provided on both sides of the flow path between the die and the roll, and at least one surface of the resin is cooled during the foaming process. Since it is cooled by the roll, the corrugation phenomenon can be prevented.

Aspect 3) In another aspect of the present invention, the pressure loss inside the extrusion die is reduced by moving the lower end on one side of the extrusion die in the thickness direction of the flow path and adjusting the thickness of the flow path in the extrusion die. It is configured to be adjustable. Aspect 4) In another aspect of the present invention, a flow path wall facing the cooling roll of the flow path between the die and the roll is constituted by a movable block, and the movable block is adjusted to change the thickness of the flow path between the die and the roll. Thus, the sheet thickness and the expansion ratio can be adjusted. The movable block may be formed separately from the extrusion die, or may be integrally formed with the extrusion die. A die-roll flow path is formed between the movable block and the outer peripheral surface of the cooling roll. I do. This movable block is a linear movement type in which the movable block is moved by a linear guide, a swing type in which the end of the extrusion die is elastically deformed,
Further, the extrusion die end may be pivotally supported by a pin or the like so as to be swingable. According to this molding apparatus, the thickness of the die-roll flow path can be adjusted, and in particular, if the fulcrum is supported so as to be elastically displaceable, it is also possible to change the thickness dimension of the ground part, which is the supporting part. In this case, in the case of simple rotation support, there is an effect that a portion having a fixed thickness and a neck cross section is variable. Further, according to the molding device, by moving the movable block,
Since the thickness of the die-roll channel at the extrusion die outlet can be adjusted, the expansion ratio and foam sheet thickness can be adjusted,
By changing the resistance of the outlet, the internal pressure of the extrusion die also changes, and the required pressure is secured.

Aspect 5) In another aspect of the present invention, means for preventing foamed gas from dissipating is provided near the exit of the die-roll passage. According to the above molding apparatus, a high-viscosity skin layer is formed on the surface layer of the foam, and the skin layer prevents the foamed gas from dissipating due to diffusion. A synergistic effect with the cooling by the cooling roll is obtained. The thickness of the skin layer varies depending on the type of foam, molding conditions, and the like, but is preferably, for example, 5 to 30% of the total thickness of the sheet. Aspect 6) In another aspect of the present invention, the foaming gas dissipation preventing means may be a cooling air knife disposed along the outer peripheral surface of the cooling roll toward the cooling roll. According to the above molding apparatus, a high-viscosity skin layer is formed on the surface layer of the foam, and the skin layer prevents the foamed gas from dissipating due to diffusion. A synergistic effect with the cooling by the cooling roll is obtained. The functions and effects of the embodiments 7) to 15) described below also prevent the dissipation due to the diffusion of the foaming gas by forming the skin layer.

Aspect 7) In another aspect of the present invention, the means for preventing foamed gas from escaping can be a cooling air chamber disposed toward a cooling roll. Aspect 8) Further, the foamed gas dissipation preventing means may be a water-cooled nozzle disposed along the outer peripheral surface of the cooling roll toward the cooling roll. Aspect 9) The above-mentioned foaming gas dissipation prevention means can be a spray device provided along the outer peripheral surface of the cooling roll toward the cooling roll. As the spray liquid used in this spray device, for example, water is preferable in consideration of the cooling effect and the post-treatment of the liquid. Aspect 10) The foamed gas dissipation prevention means can be a small roll capable of adjusting the temperature and arranged along the outer peripheral surface of the cooling roll in the rotation direction of the cooling roll. It is preferable that a plurality of the small rolls are provided at a fixed gap from the cooling roll. Aspect 11) The gas dissipation preventing means can be a temperature-adjustable belt disposed along the outer peripheral surface of the cooling roll. Aspect 12) The gas dissipation preventing means may be gas blowing means for blowing a cooling gas toward the foam. The cooling gas is preferably liquid nitrogen gas or carbon dioxide gas. Aspect 13) The foam gas dissipation preventing means may be a water tank in which the foam is immersed in cooling water. Aspect 14) The foamed gas dissipation preventing means can be constituted by a multilayer molding die in which a non-foamable molten resin is laminated on the front and / or back surface of the foamable molten resin. Aspect 15) The foaming gas dissipation preventing means may be a thermal laminator for performing thermal laminating on the foam discharged from the extrusion die. This thermal lamination is a heat bonding type lamination, and is for bonding a sheet-like member to the surface of the foam.

Aspect 16) In another aspect of the present invention, a surface roughness preventing means for improving the releasability from resin can be provided on the flow path wall surface of the movable block. According to this molding apparatus, the releasability of the foam from the movable wall surface forming the die-to-roll flow path is improved, and the phenomenon of foam breakage due to shearing can be prevented. Aspect 17) In another aspect of the present invention, the surface roughening prevention means adjusts the temperature of the outflow portion of the movable block so as to be lower than the resin temperature to improve the releasability between the movable block and the resin. Can be. According to this molding device,
Since the resin discharged from the extrusion die comes into contact with the flow path wall forming the die-roll flow path with low friction characteristics, the releasability of the flow path wall from the foam is improved, and the foam is broken by shearing of the foam. The phenomenon can be prevented. Aspect 18) In another aspect of the present invention, the surface roughening prevention means may be a Teflon coating treatment applied to the flow path wall surface of the movable block to reduce the frictional force. Since this Teflon has a high heat resistance temperature and a small coefficient of friction, the surface on which the Teflon film is formed by the Teflon coating treatment has good releasability from the foam on the wall surface of the flow path, and the foam breaks due to shearing of the foam. The phenomenon can be prevented. Aspect 19) In another aspect of the present invention, the surface roughness preventing means may be a satin finish applied to the flow path wall surface of the movable block to reduce the frictional force. The surface subjected to this treatment is filled with a gas foamed from a resin in the satin-like concave portion to form a gas film. The gas film acts as a gas bearing, so that the releasability of the flow path wall surface from the foam is improved, and the foam breaking phenomenon due to shearing of the foam can be prevented.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A foam sheet and a film forming apparatus according to the present invention will be specifically described below with reference to FIGS. In the following embodiments, a case where a foamable resin sheet is formed will be described. However, the present invention has versatility and can be applied to a foamable resin film.

[First Embodiment] A molding apparatus 10 according to a first embodiment includes an extrusion die 1 as shown in FIG.
1, a cooling air knife 12a, 12b, 12c, a cooling roll 13, and a take-up roll 14. Inside the extrusion die 11, an extrusion die flow path A for the molten resin is disposed along the vertical direction with a certain gap from 3a. The cooling roll 13 is rotatably supported in a counterclockwise direction, and is arranged to cool the foamable molten resin 15 discharged from the extrusion die 11. On the left side of the cooling roll 13, a cooling air knife 12a, 1
2b and 12c are provided, and a skin layer 52a described later is formed by blowing air on the surface of the foam 16 extruded on the outer peripheral surface 13a of the cooling roll 13. A take-up roll 14 is supported obliquely above the cooling roll 13 so as to be rotatable clockwise, and supplies the foam 16 sent from the cooling roll 13 to a next step (not shown). Next, the structure near the extrusion die 11 will be described with reference to FIG.

As shown in FIG. 2, the extrusion die 11 includes two extrusion die fixing blocks 11a and 11
b, a storage section 53 for vertically storing the foamable molten resin 15 therein and an extrusion die flow path A communicating with the storage section 53 are formed inside the storage section 53. The storage section 5
3 is a manifold portion 53a formed in a substantially spherical upper portion.
And a pre-land portion 53b which is provided in communication with the lower portion of the manifold portion 53a and whose diameter is sharply reduced at the center in the height direction. Further, the lower end portions 54a and 54b of the extrusion die flow path A are opened downward, so that the foamable molten resin 15 is discharged, and are formed integrally with the extrusion die fixing block 11a. The lower end portion 54a is elastically deformable in a substantially horizontal direction. Hereinafter, the vicinity of the lower end of the extrusion die flow path A is referred to as a grounding part B.
That. A movable block 24a is attached to the lower end of the extrusion die fixing block 11b substantially in parallel with the outer peripheral surface 13a of the cooling roll 13, and the movable block 24a depends on the thickness of the foam 16 to be molded. Can be replaced with various sizes. The movable block 24a has a lower surface formed on a low friction surface, and is movable up and down while rotating in a state substantially parallel to the outer peripheral surface 13a of the cooling roll 13 by rotating a die-roll gap adjusting bolt 23. Can be done. Therefore, when the movable block 24a is moved diagonally upward, the die-to-roll flow path thickness F increases, and when the movable block 24a is moved diagonally downward, the die-to-roll flow path thickness F decreases.

A ground contact gap adjusting bolt 25 is fixed to the lower end 54a of the extrusion die fixing block 11a. The ground contact gap adjusting bolt 25 is rotated to move the lower end 54a to the right in FIG. By elastically deforming in the direction, the extrusion die channel thickness E of the extrusion die channel A can be increased. Also, the extrusion die channel thickness E and the die
The relationship with the inter-roll channel thickness F is E <F, and the grounding portion B
In, the flow channel thickness suddenly increases from E to F, and the enlargement ratio F / E can be appropriately adjusted according to the expansion ratio of the foam.
That is, the relationship between the extrusion die channel thickness E and the straightening portion die-to-roll channel thickness F is expressed by expansion ratio = F / E. Further, in order to cool the foamable molten resin 15 housed in the extrusion die flow path A, the refrigerant passages 22a, 22b, 22c are formed.
Is formed on the extrusion die 11. This refrigerant passage 22a
Is formed at an upper position of the extrusion die channel A, and the refrigerant passage 2
2b is formed near the ground portion B, and the refrigerant passage 22c is
It is formed inside the movable block 24a. Therefore,
The refrigerant passage 22a cools the foaming molten resin 15 stored inside the extrusion die 11, and the refrigerant passage 22b communicates with the foaming molten resin stored inside the extrusion die fixing blocks 11a and 11b near the grounding portion B. 15 to cool the refrigerant passage 22
c is a die of the movable block 24a and the cooling roll 13;
The surface side of the foam 16 in the inter-roll passage C, that is, the surface on the movable block 24a side is cooled. The operation of the molding apparatus 10 according to the first embodiment having the above configuration will be described below.

Under the required molding conditions, the foamable molten resin 15 passes through the extrusion die channel A from the storage part 53 of the extrusion die 11, and is extruded from the grounding portion B to the die-roll channel C. When the extruded foamable molten resin 15 comes into contact with the outer peripheral surface 13a of the cooling roll 13, the back surface on the cooling roll 13 side is cooled to form a high-viscosity skin layer 52b. As described above, the foam 16 in the die-roll passage C is cooled by flowing the refrigerant through the refrigerant passage 22c, and the lower surface of the movable block 24a is formed on the low friction surface H having low friction characteristics. Since it is formed, the releasability of the expandable molten resin 15 from the movable block 24a in the die-to-roll flow path C is improved, and the bubble breaking phenomenon due to the shearing of the resin can be prevented.

The foamable molten resin 15 is extruded from the extrusion die 11 through the grounding portion B under required molding conditions. Immediately thereafter, the molten resin 15 on the cooling roll 13 side
3 and cooled, and a high-viscosity skin layer 52b is formed on the surface layer. In the grounding portion B, the thickness of the flow channel is suddenly increased, and the foamable molten resin 15 expands and starts to foam. In the die-to-roll flow path C, rapid expansion of the foam is suppressed. Also, as shown in FIG. 4, the side face of the die-to-roll flow path C is provided with a side flow path wall 24c. Expansion is restrained, and the corrugation phenomenon can be prevented.

As described above, the cooling roll 13 of the foam 16
Since the high-viscosity skin layers 52a and 52b are formed on both sides (the back side) and the extrusion die 11 side (the front side), it is possible to prevent foam gas from being dissipated due to the foam gas diffusion phenomenon. The length G of the die-to-roll flow path needs to be set to a length that does not cause a bubble breaking phenomenon due to shearing in the straightening part die-to-roll flow path C. The movable block 24a
Has a separate structure from the extrusion die fixing block 11b.
As shown in FIG. 3, the movable block 24b may be formed integrally with the extrusion die fixing block 11b. The movable block 24b is flexed in the vertical direction with its root I as a center axis by the die-to-roll gap adjusting bolt 23, so that no step is generated in the grounding portion B and the foamable molten resin 15 Flow can be achieved.

[Second Embodiment] Next, FIGS.
A second embodiment relating to means for cooling the front side of the foam 16 discharged from the outflow portion D located at the end of the movable blocks 24a and 24b will be described using FIG. As shown in FIG. 5, the molding apparatus 10 has an air chamber 31 whose tip is directed toward the cooling roll 13.
The upper end of the air chamber 31 is disposed at a position substantially at the same height as the outflow portion D, and the amount of the blown air 31a can be appropriately changed by an adjusting mechanism (not shown).

According to the molding apparatus 10 having the above configuration,
By cooling the foam 16 flowing out of the outflow portion D by the air 31a sent from the air chamber 31, a high-viscosity skin layer 52a is formed on the surface layer of the foam 16 on the air chamber 31 side. This has the effect of preventing gas dissipation due to the gas diffusion phenomenon.
In the forming apparatus 10 shown in FIG. 6, the tip of the water-cooled nozzle 3
2 are arranged. The water cooling nozzle 32 is also configured such that the discharge amount of the cooling water 32a can be adjusted by a common means (not shown).

According to the molding apparatus 10 having the above configuration,
By spraying cooling water 32a from a plurality of water cooling nozzles 32 on the foam 16 flowing out from the outflow portion D and cooling it, a high-viscosity skin layer 52a is formed on the surface layer of the foam 16, and as a result, It has the effect of preventing gas dissipation due to the diffusion phenomenon. Forming device 10 shown in FIG.
In the vicinity of the extrusion die 11, a plurality of spray nozzles 33 are provided with their tip portions facing the cooling roll 13.
The spray nozzle 33 is capable of spraying a spray liquid 33a, for example, cooling water whose temperature has been adjusted, onto the foam 16, and is configured such that the spray amount can be appropriately adjusted by conventional means (not shown).

According to the molding apparatus 10 having the above configuration,
By spraying the spray liquid 33a from the plurality of spray nozzles 33 onto the foam 16 flowing out from the outlet portion D and cooling it, a high-viscosity skin layer 52a is formed on the surface layer of the foam 16, and as a result, the foaming gas This has the effect of preventing gas from being dissipated due to the diffusion phenomenon. Forming apparatus 10 shown in FIG.
A plurality of small roll groups 34 are rotatably arranged along the outer circumference of the cooling roll 13 at a constant gap from the outer peripheral surface 13a. These small roll groups 34
The surface temperature of the cooling roll 13 can be appropriately adjusted by means not shown, and rotates in a direction opposite to the rotation direction of the cooling roll 13. According to the molding apparatus 10 having the above-described configuration, the plurality of temperature-controlled small roll groups 34 are rotated and abut against the surface side of the foam 16 flowing out from the outflow portion D, and the foam 16 is removed. Cooling. Therefore, a high-viscosity skin layer 52a is formed on the surface layer of the foam 16,
As a result, an effect of preventing gas dissipation due to the diffusion phenomenon of the foaming gas is exerted.

In the forming apparatus 10 shown in FIG. 9, two belt guide rolls 36a and 36c separated from the outer peripheral surface 13a of the cooling roll 13 by a fixed gap, and substantially the same distance from these belt guide rolls 36a and 36c. One belt guide roll 36b is disposed at a distance, and the belt 35 is configured such that the temperature can be adjusted by means (not shown) on these three belt guide rolls 36a, 36b, and 36c.
Is wound. According to the molding apparatus 10 having the above configuration, the foam 16 is cooled by bringing the belt 35 whose temperature has been adjusted into contact with the surface of the foam 16 flowing out of the outflow portion D. Therefore, a high-viscosity skin layer 52a is formed on the surface layer of the foam 16, and as a result, an effect of preventing gas dissipation due to a diffusion phenomenon of the foaming gas is exerted. The extrusion device 1 shown in FIG.
A gas blowing device 37 is disposed below the cooling roll 1 at a constant distance from the outer peripheral surface 13 a of the cooling roll 13. The gas spraying device 37 can blow liquefied nitrogen gas or carbon dioxide gas 37a, and these liquefied nitrogen gas or carbon dioxide gas 37a are configured so that temperature adjustment and wind pressure to be blown can be adjusted by means not shown. I have. According to the molding apparatus 10 having the above configuration, the foam 16 is cooled by spraying the liquefied nitrogen gas or the carbon dioxide gas 37a on the surface side of the foam 16 flowing out of the outflow portion D. Therefore, a high-viscosity skin layer 52a is formed on the surface layer of the foam 16, and as a result, an effect of preventing gas dissipation due to a diffusion phenomenon of the foaming gas is exerted.

The cooling device 3 shown in FIG.
The cooling roll 13 is immersed in a water tank 39 containing the cooling water 8, and the cooling water 38 is configured so that the temperature can be adjusted by means (not shown). According to the molding apparatus 10 having the above configuration, the foam 16 flowing out of the outflow portion D is immersed in the cooling water 38 and allowed to pass through, thereby cooling the foam 16. For this reason, a high-viscosity skin layer 52a is formed on the surface layer of the foam 16, and as a result,
This has the effect of preventing gas dissipation due to the foaming gas diffusion phenomenon. According to the plurality of means described above, according to the molding apparatus 10 of the second embodiment, it is possible to prevent gas dissipation due to the foaming gas diffusion phenomenon, and to obtain a foam sheet having a predetermined foaming ratio.

[Third Embodiment] Next, a third embodiment will be described with reference to FIGS. The molding apparatus 10 shown in FIG. 12 has two inflow paths 56 inside a multilayer mechanism 42 disposed upstream of the extrusion die 11.
a, 56b, and an introduction path 57 is formed between the inflow paths 56a, 56b. These inflow paths 56a, 56
The b and the introduction path 57 join at the lower part of the multilayer mechanism 42 and communicate with the storage section 53 of the extrusion die 11. The operation of the molding apparatus 10 having the above configuration will be described. First, the foamable molten resin 15 flows into the introduction path 57 and the non-foamable molten resin 41 flows into the flow paths 56a and 56b. The non-foamable molten resin 41 is laminated on both the front and back sides of the foamable molten resin 15 before flowing out of the extrusion die 11 to form a multilayer structure. Thereby, the foamed gas dissipation prevention layer 52c is formed on the surface layer of the foam body 16,
This has the effect of preventing gas dissipation due to the foaming gas diffusion phenomenon.

The molding apparatus 10 shown in FIG. 13 includes the belt guide rolls 36a, 36b, and 36c shown in FIG. 9 and a belt 35 wound around these roll groups 36, and uses these to form a non-foaming resin. The sheet 45 is subjected to thermal lamination on the foamable resin sheet surface. In the forming apparatus 10 shown in FIG. 14, a guide roll 36a is pivotally supported at a lower portion of the extrusion die 11 with a gap from the cooling roll 13, and a roll 36d is rotatable beside the guide roll 36a. It is pivoted. A non-foamable resin sheet 45 is wound around the guide roll 36d, and is formed so as to be subjected to thermal lamination on the surface of the foam 16 via the guide roll 36a. Here, the thermal lamination means that the non-foamable resin sheet 45 is brought into contact with the outer peripheral surface 13a of the cooling roll 13 and the belt 35
Is caused to adhere to the surface of the foam 16 by the heat.
Thereby, the foamed gas dissipation prevention layer 5 is formed on the surface of the foam 16.
2c is formed to prevent the gas from dissipating due to the diffusion of the foaming gas.

[Fourth Embodiment] FIGS. 2 and 3
The fourth embodiment will be described with reference to FIG. As is apparent from these figures, a refrigerant passage 22c is formed in the movable blocks 24a and 24b, and the refrigerant flows through the refrigerant passage 22c. With this configuration, the movable block 24a,
24b is cooled below the resin temperature, the releasability of the foam 16 from the surface of the flow path is improved, and the phenomenon of foam breakage due to shearing is prevented. As a result, the drawback of the foam 16 being reduced in magnification is eliminated. Table 1 shows the surface state and expansion ratio of the foam 16 when the temperature of the movable blocks 24a and 24b is changed with respect to the resin temperature of 170 ° C. In this table, ◎ indicates good surface properties, O indicates almost good, and × indicates poor.

[0030]

[Table 1]

As shown in Table 1, the movable block 2
By lowering the temperature of the outlet portions of 4a and 24b below the resin temperature, the adhesiveness is reduced, so that the resin separation is improved,
The surface condition of the foam 16 becomes good. In addition, the foam 16
The surface layer has a high viscosity, and a foaming gas dissipation prevention layer 52c is formed, which has an effect of preventing gas dissipation due to a foaming gas diffusion phenomenon. [Fifth Embodiment] FIG.
The fifth embodiment will be described with reference to FIG. This figure is an enlarged sectional view of the vicinity of the ground contact portion B in FIG. 2 or FIG. 3, and is an enlarged sectional view of the low friction surface H in FIG. 2 and FIG. The low friction layer 46 can be formed on the flow path surface 47 of the movable blocks 24a and 24b by using, for example, a Teflon coating process or a satin finish. According to the above configuration, since the flow path surface 47 has been subjected to the low friction treatment, the shearing force of the foam 16 in the die-roll flow path C can be reduced to prevent the foam breaking phenomenon. The problem of reducing the magnification is eliminated.

[0032]

According to the present invention, it is possible to obtain a foamed sheet or film in which the curtain wall phenomenon does not occur, the foaming gas is dissipated, and the expansion ratio does not decrease.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an entire molding apparatus according to a first embodiment.

FIG. 2 is a sectional view showing the vicinity of an extrusion die in FIG.

FIG. 3 is a sectional view showing the vicinity of an extrusion die in FIG.

FIG. 4 is a sectional view taken along line XX in FIG.

FIG. 5 is a cross-sectional view showing the entire molding apparatus provided with an air chamber according to a second embodiment.

FIG. 6 is a cross-sectional view illustrating an entire molding apparatus provided with a water-cooling nozzle according to a second embodiment.

FIG. 7 is a cross-sectional view showing the entire molding apparatus provided with a spray nozzle according to a second embodiment.

FIG. 8 is a cross-sectional view showing the entire forming apparatus provided with a group of small rolls according to the second embodiment.

FIG. 9 is a cross-sectional view illustrating an entire forming apparatus provided with a belt and guide rolls according to a second embodiment.

FIG. 10 is a cross-sectional view showing an entire molding apparatus provided with a gas blowing device according to a second embodiment.

FIG. 11 is a cross-sectional view showing the entire molding apparatus according to a second embodiment for allowing a foam to pass through a cooling water tank.

FIG. 12 is a cross-sectional view showing an entire molding apparatus provided with a multilayer mechanism according to a third embodiment.

FIG. 13 is a cross-sectional view showing the entire molding apparatus provided with a belt-type thermal laminating mechanism according to a third embodiment.

FIG. 14 is a cross-sectional view illustrating an entire molding apparatus provided with a roll-type thermal laminating mechanism according to a third embodiment.

FIG. 15 is a sectional view showing a movable block having a low friction layer according to a fifth embodiment.

FIG. 16 is a cross-sectional view illustrating a conventional T die for sheet extrusion.

17 is a sectional view taken along line YY in FIG.

18 is a sectional view taken along line ZZ in FIG.

FIG. 19 is a graph showing a resin pressure inside a conventional T-die for sheet extrusion molding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Forming apparatus 11 Extrusion die 11a, 11b Extrusion die fixing block 12a, 12b, 12c Cooling air knife 13 Cooling roll 13a Outer peripheral surface 14 Take-off roll 15 Foamable molten resin 16 Foam 22a, 22b, 22c Refrigerant passage 23 Die-roll gap Adjusting bolts 24a, 24b Movable block 24c Side passage wall 25 Ground clearance adjusting bolt 31 Air chamber 32 Water cooling nozzle 32a, 38 Cooling water 33 Spray nozzle 33a Spray liquid 34 Small roll group 35 Belts 36a, 36b, 36c Belt guide roll 37 Gas spraying device 37a Liquefied nitrogen gas or carbon dioxide gas 39 Water tank 41a, 41b Non-foamable molten resin 42 Multi-layer mechanism 43 Thermal laminating mechanism 45 Non-foamable resin sheet 46 Low friction layer 47 Channel surface 52a, 52b Layer 53 Storage part 53a Manifold part 53b Preland part 54 Lower end part 54a Lower end part of extrusion die fixing block 11a 54b Lower end part of extrusion die fixing block 11b A Extrusion die flow path B Grounding part C Die-roll flow path D Outflow part E Extrusion die channel thickness F Die-roll channel thickness G Straightener die-roll channel length H Low friction surface I Root

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) B29L 7:00 (72) Inventor Ryoji Mohri 1 Takamichi Iwazuka-cho, Nakamura-ku, Nagoya-shi, Aichi Prefecture Mitsubishi Heavy Industries, Ltd. (72) Inventor Masahiro Tsuboi, Nagoya Aichi, Nagoya-shi, Iwatsuka-cho, Takamichi 1, Mitsubishi Heavy Industries, Ltd.Nagoya Equipment Works (72) Inventor Hideo Yoneya, Ichizuka, Nakamura-ku, Aichi, Japan No. 1 F-term in Nagoya Machinery Works, Mitsubishi Heavy Industries, Ltd. (reference) 4F207 AA11 AG01 AG20 AH26 AH46 AJ03 AK00 AM32 AR06 KA01 KA11 KA17 KK55 KK56 KK64 KL49 KL62 KL84 KL86 KL91

Claims (19)

[Claims] 1. A cooling roll rotatably supported, an extrusion die disposed close to an outer peripheral surface of the cooling roll,
An extrusion die channel formed inside the extrusion die, the tip of which extends to the outer peripheral surface of the cooling roll, and is formed between the end of the extrusion die and the cooling roll following the extrusion die channel. A foamed sheet and film forming apparatus, comprising: a die-to-roll flow path. 2. The flow path thickness of the die-roll flow path,
2. The foamed sheet according to claim 1, wherein an extension of the extrusion die flow path is formed to be larger than a flow path thickness of the extrusion die flow path with respect to a ground portion intersecting an outer peripheral surface of the cooling roll. And film forming equipment. 3. The resin pressure loss can be adjusted by changing the thickness of the flow path in the extrusion die.
The foamed sheet and film forming apparatus according to 1. 4. A flow path wall of the flow path between the die and the roll facing the cooling roll is composed of a movable block, and the thickness of the sheet is increased by adjusting the movable block to change the thickness of the flow path between the die and the roll. The foam sheet and film forming apparatus according to claim 3, wherein the magnification is adjustable. 5. The foamed sheet and film forming apparatus according to claim 1, further comprising means for preventing foamed gas from dissipating near an outlet of the die-to-roll flow path. 6. The foamed sheet and film forming apparatus according to claim 5, wherein said foaming gas dissipation preventing means is a cooling knife disposed along an outer peripheral surface of the cooling roll toward the cooling roll. apparatus. 7. The foamed sheet and film forming apparatus according to claim 5, wherein said foamed gas dissipation prevention means is a cooling air chamber provided toward a cooling roll. 8. The foamed sheet and film according to claim 5, wherein the foamed gas dissipation preventing means is a water-cooled nozzle disposed along an outer peripheral surface of the cooling roll toward the cooling roll. Molding equipment. 9. The foamed sheet according to claim 5, wherein the foamed gas dissipation prevention means is a spray device disposed along an outer peripheral surface of the cooling roll toward a cooling roll. Film forming equipment. 10. The foamed sheet and film forming apparatus according to claim 5, wherein said foamed gas dissipation preventing means is a small temperature-adjustable roll disposed along the outer peripheral surface of the cooling roll. apparatus. 11. The foamed sheet and film forming apparatus according to claim 5, wherein the foamed gas dissipation prevention means is a temperature-adjustable belt disposed along the outer peripheral surface of the cooling roll. . 12. The foamed sheet and film forming apparatus according to claim 5, wherein said foamed gas dissipation preventing means is a gas blowing means for blowing a cooling gas toward said foam. 13. The foamed sheet and film forming apparatus according to claim 5, wherein the foamed gas dissipation preventing means is a water tank for immersing the foamed body in cooling water. 14. The foam sheet according to claim 5, wherein the foaming gas dissipation preventing means is a multilayer molding die for laminating a non-foamable molten resin on the front surface and / or the back surface of the foamable molten resin. And film forming equipment. 15. The foamed sheet and film forming apparatus according to claim 5, wherein the foamed gas dissipation preventing means is a thermal laminating apparatus for performing thermal laminating on the foam discharged from the extrusion die. 16. The foam sheet and film forming apparatus according to claim 4, wherein a surface roughness preventing means for improving releasability from resin is provided on a flow path wall surface of the movable block. 17. The surface roughening prevention means adjusts a temperature of an outflow portion of the movable block to be lower than a resin temperature,
17. The foam sheet and film forming apparatus according to claim 16, wherein the releasability between the movable block and the resin is improved. 18. The foam sheet and film forming apparatus according to claim 16, wherein the surface roughening prevention means is a Teflon coating process performed on a flow path wall surface of the movable block to reduce a frictional force. 19. The foam sheet and film forming apparatus according to claim 16, wherein the surface roughening prevention means is a matte finish processing performed on a flow path wall surface of the movable block to reduce a frictional force.