JP3782595B2 - Flat die for extrusion molding - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flat die for extrusion molding, and more particularly, to a flat die used for coextrusion molding by an in-die lamination method.
[0002]
[Prior art]
In general, a flat die 1 used for co-extrusion molding by an in-die lamination method is provided with a plurality of manifolds 2a, 2b, 2c for accumulating molten resin inside the die, as shown in FIG. 6 (a). These manifolds 2a, 2b, and 2c are places where the molten resin that is extruded from the extruder and passes through the resin introduction paths 7a, 7b, and 7c is temporarily stored. The manifolds 2a, 2b, and 2c communicate with the resin layer forming paths 3a, 3b, and 3c, and the molten resin is formed into a sheet shape through the resin layer forming paths 3a, 3b, and 3c. And each said resin sheet is laminated | stacked by the laminated part 4 where the said resin layer formation path 3a, 3b, 3c merges. The obtained laminated sheet is sent out through the laminated body extrusion path 5.
[0003]
As shown in FIG. 6B, the cross-sectional shapes of the resin forming paths 3a, 3b, and 3c at this time have the same rectangular shape, and the obtained laminated sheet has a cross-sectional shape from the same rectangular shape. It becomes what laminated | stacked the resin sheet which becomes.
[0004]
[Problems to be solved by the invention]
By the way, after the obtained laminated sheet is stretched, both side portions thereof are cut off, and only the central portion is wound and used. This is because the both sides are gripped by the grip when stretched, and this portion is not easily stretched.
[0005]
Since both side portions of the cut laminated sheet contain a plurality of resin components, it is difficult to recycle as it is. Moreover, it is difficult to separate each resin component.
[0006]
Then, the subject of this invention is improving the recyclability of the both sides of the extending | stretching laminated sheet with low recyclability.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a plurality of manifolds for retaining molten resin, and joins the resin layer formation paths communicating with the respective manifolds at the laminated portions, and from the laminated portions toward the outside. In a flat die for extrusion molding provided with a laminate extrusion path, the cross-sectional shape of at least one resin layer formation path among the plurality of stages of resin layer formation paths is such that both side portions are both sides of other resin layer formation paths A bulging part protruding from the part is formed.
[0008]
Since both side portions of at least one resin layer forming path form a bulging portion that protrudes from both side portions of the other resin layer forming path, both sides of the resulting laminated sheet are mainly composed of a resin that forms the bulging portion. Become. For this reason, after extending | stretching, one resin component becomes a main component in the both sides cut off. For this reason, the recyclability of both sides can be enhanced.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS.
[0010]
As shown in FIG. 1, the flat die 11 for extrusion molding according to the present invention continuously forms a molten resin extruded from a plurality of extrusion molding machines 12a, 12b, and 12c into a sheet shape therein, and A die to be laminated. That is, it is a die used for coextrusion molding by an in-die lamination method.
[0011]
As shown in FIG. 2A, the flat die 11 is provided with a plurality of stages of manifolds 13a, 13b, and 13c, and resin layer forming paths 15a, 15b, and 15c communicating with the manifolds 13a, 13b, and 13c are stacked. 16, the laminated body extrusion path 17 is provided from the laminated portion 16 to the outside.
[0012]
A plurality of stages of manifolds 13a, 13b, and 13c are provided inside the flat die 11. The number of stages is not limited to the three stages as shown in FIG. 2 (a), but may be at least two stages from the viewpoint of producing a laminated sheet, and preferably 3 to 5 stages. Hereinafter, the case where the three-stage manifolds 13a, 13b, and 13c are provided will be described.
[0013]
As shown in FIG. 2B, the manifolds 13a, 13b, and 13c have a shape that is long in the width direction, and are for temporarily retaining the molten resin. These manifolds 13a, 13b, and 13c are provided so that their length directions are parallel to each other. In these manifolds 13a, 13b, and 13c, as shown in FIG. 2A, a resin introduction path 14a for introducing the resin extruded from the extruders 12a, 12b, and 12c into the manifolds 13a, 13b, and 13c. , 14b, 14c are connected.
[0014]
As shown in FIGS. 2A and 2B, outlets having the same width as the longitudinal directions of the manifolds 13a, 13b, and 13c, that is, die slits 18a, 18b, and 18c are provided. It is done. These die slits 18a, 18b, 18c communicate with the resin forming paths 15a, 15b, 15c. Since these resin formation paths 15a, 15b, and 15c have the same width and predetermined height as the manifolds 13a, 13b, and 13c, the molten resin passing through the resin formation paths 15a, 15b, and 15c is formed into a sheet shape. Molded. And in the lamination | stacking part 16, each resin sheet of the molten state which passes each resin formation path 15a, 15b, 15c is laminated | stacked. At this time, since each resin sheet is still in a molten state, the bondability between the layers is good. The laminated sheets thus laminated are pushed out from the laminated body extrusion path 17.
[0015]
Among the three-stage resin layer forming paths 15a, 15b, and 15c, the cross-sectional shape of the resin forming path 15b located inside is different from the other resin layer forming paths 15a and 15c. That is, as shown in FIG. 2C, the cross-sectional shape of the resin formation path 15b forms a bulging portion 19 that protrudes from both side portions of the other resin layer formation paths 15a and 15c at both side portions. Since the bulging portion 19 protrudes from both side portions of the other resin layer forming paths 15a and 15c, when the three layers are stacked, the bulging portion 19 does not disturb the stacking. Moreover, since the thickness of the bulging portion 19 is provided in both directions of the resin layer forming paths 15a and 15c and by the thickness of the resin layer forming paths 15a and 15c, after the lamination, the above other resins The bulging part 19 of the resin formation path 15b is arranged on the outer side of the both ends of the resin sheet from the layer formation paths 15a and 15c, and a substantially uniform thickness can be obtained as the whole laminate.
[0016]
The resin layer forming path having the bulging portions 19 on both sides is provided with at least three resin layer forming paths, and at least one resin layer forming path located on the inner side of the plurality of resin layer forming paths. Although it is preferable to provide a bulging part, it is not limited to this. That is, there may be a plurality of stages, that is, at least two stages of resin layer forming paths, and at least one resin layer forming path of which the bulging portions 19 are provided on both sides.
[0017]
As an example of this, there is a case where there are a plurality of resin layer forming paths and the resin layer forming paths having the bulging portions 19 on both sides are arranged on the outside. As a specific example, a flat die 11 ′ having three stages of resin layer forming paths 15a ′, 15b ′, 15c ′ as shown in FIG. In this case, the cross-sectional shape of the resin forming path 15c ′ located outside forms a bulging part 19 ′ protruding from both side parts of the other resin layer forming paths 15a ′ and 15b ′. Since this bulging portion 19 ′ protrudes from both side portions of the other resin layer forming paths 15 a ′ and 15 b ′, when the three layers are stacked, the bulging portion 19 does not disturb the stacking. Moreover, since the thickness of the bulging portion 19 ′ is provided in the direction of the resin layer forming paths 15a ′ and 15b ′ and the total thickness of the resin layer forming paths 15a ′ and 15b ′, after lamination, The bulging portions 19 ′ of the resin forming path 15c ′ are arranged outside the both ends of the resin sheet formed from the other resin layer forming paths 15a ′ and 15b ′, and the entire laminate has a substantially uniform thickness. Obtainable.
[0018]
Next, a method for producing a biaxially stretched laminated film using the flat die 11 according to the present invention will be described.
[0019]
As shown in FIG. 1, each resin is put into a predetermined number (three in FIG. 1) of extruders 12a to 12c, and melted and kneaded. Then, these molten resins are introduced into the flat die 11 and molded and laminated. The laminated sheet 21 is extruded from the exit of the laminated body extrusion path 17 and sent to the cooling process (process X in FIG. 1). In this process X, it cools by the press by the rolls 22 and 23, and standing to cool.
[0020]
Then, in the longitudinal stretching step (step Y in FIG. 1), the rotational speed of the roll 25 is made faster than the rotational speed of the roll 23 while the laminated sheet 21 is heated by the heater 24. Thereby, in the process Y, extending | stretching is applied to the advancing direction of the lamination sheet 21, ie, the vertical direction. This draw ratio can be set by the rotational speed ratio between the roll 25 and the roll 23.
[0021]
Next, in the transverse stretching step (step Z in FIG. 1), both side portions of the laminated sheet 21 are sequentially held by a large number of clips 26. The clips 26 are connected to endless conveyors 27 provided on both sides of the laminated sheet 21, and the two endless conveyors 27 are spread outward in the direction perpendicular to the traveling direction of the laminated sheet 21. .
[0022]
For this reason, in this process Z, first, the clip 26 is moved according to the movement of the endless conveyor 27 with the both ends of the laminated sheet 21 stretched longitudinally interposed therebetween. Since the endless conveyor 27 spreads outward in the direction perpendicular to the traveling direction of the laminated sheet 21, the clip 26 moves accordingly, and the laminated sheet 21 extends in a direction perpendicular to the traveling direction, that is, in the lateral direction. Is done.
[0023]
As shown in FIG. 4, the biaxially stretched laminated sheet 21 ′ occupies most of one resin on both sides.
[0024]
The obtained biaxially stretched laminated sheet 21 ′ is used after being wound with its both sides cut. When the layer components on both sides of the cut are present almost evenly, when this is recycled, only a few percent can be mixed with one of the raw material resins for producing the laminated sheet, but this invention was used. Since both sides of the resulting biaxially stretched sheet 21 ′ are mainly composed of one resin, it can be mixed with at least 15% of the raw material resin for producing the laminated sheet, and the recycling rate can be increased. Can be improved.
[0025]
Further, the flat die 11 according to the present invention is not limited to the case of the above-described sequential stretching method, and can also be used in the case of the simultaneous biaxial stretching method as shown in FIG. As shown in FIG. 5, this is the same method as the sequential stretching method except for the following points. That is, the step Y and the step Z of the sequential stretching method are the simultaneous biaxial stretching steps (step W in FIG. 5). In this process W, the laminated sheet heated by the heater 24 is longitudinally stretched by changing the rotation speeds of the rolls 23 and 28, and the lateral stretching is performed by the belt conveyor 27 and the clip 26 according to the above method. To do.
[0026]
Also by this method, the obtained biaxially stretched laminated sheet has a cross section as shown in FIG. 4 and can increase the recycling rate of both sides to be cut.
[0027]
【The invention's effect】
According to this invention, since the specific one resin is a main component in both sides of the obtained biaxially stretched laminated sheet, the rate of addition of the biaxially stretched laminated sheet to the production raw material can be improved. it can. That is, it is possible to improve the recycling rate on both sides and improve the recyclability. Furthermore, the amount of raw material resin used can be reduced, and the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of an apparatus for producing a stretched sheet by a sequential stretching method. FIG. 2A is a cross-sectional view showing an example of a flat die of the present invention. ) (A) BB sectional view [FIG. 3] FIG. 4 is a sectional view showing an example of another flat die of the present invention. [FIG. 4] FIG. 5 is a sectional view of a laminated sheet obtained by the apparatus shown in FIG. Schematic diagram illustrating an example of a stretched sheet manufacturing apparatus using the simultaneous stretching method. FIG. 6A is a cross-sectional view illustrating an example of a conventional flat die. FIG. 6B is a cross-sectional view of FIG.
DESCRIPTION OF SYMBOLS 1 Flat die 2a, 2b, 2c Manifold 3a, 3b, 3c Resin formation path 4 Lamination | stacking part 5 Laminated body extrusion path 7a, 7b, 7c Resin introduction path 11, 11 'Flat die 12a, 12b, 12c Extruders 13a, 13b , 13c Manifold 14a, 14b, 14c Resin introduction path 15a, 15b, 15c, 15a ', 15b', 15c 'Resin layer forming path 16 Laminating part 17 Laminate extrusion path 18a, 18b, 18c Die slit 19, 19' Swelling part 21 Laminated sheet 21 ′ Biaxially stretched laminated sheet 22 Roll 23 Roll 24 Heater 25 Roll 26 Clip 27 Belt conveyor 28 Roll

Claims (2)

A flat die for extrusion molding in which a plurality of manifolds for retaining molten resin are provided, resin layer formation paths communicating with the respective manifolds are joined at the lamination section, and a laminate extrusion path is provided from the lamination section to the outside. In
The manifold and the resin layer forming path are provided in at least three stages,
Of the plurality of resin layer forming paths, the cross-sectional shape of at least one resin layer forming path located inside forms a bulge portion that protrudes from both side parts of the other resin layer forming path ,
The bulging portion is provided toward both sides of the other resin layer forming path, and has a thickness corresponding to the thickness of the other resin layer forming path, and has a thickness corresponding to the thickness of the other resin layer forming path. Die. A flat die for extrusion molding in which a plurality of manifolds for retaining molten resin are provided, resin layer formation paths communicating with the respective manifolds are joined at the lamination section, and a laminate extrusion path is provided from the lamination section to the outside. In
The manifold and the resin layer forming path are provided in at least three stages,
Of the plurality of resin layer forming paths, the cross-sectional shape of at least one resin layer forming path arranged outside forms a bulge portion that protrudes from both side parts of the other resin layer forming paths on both sides thereof. ,
The bulge portion is provided toward the other resin layer forming path, and has a thickness corresponding to the total thickness of the other resin layer forming path. .

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