JPH0159900B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention is used in the technical field of multilayer dies connected to synthetic resin extruders.

BACKGROUND OF THE INVENTION Multilayer dies such as those described above are well known in the art.
For example, a four-layer die is disclosed in Japanese Patent Publication No. 49-1628. In this case, two layers each were stacked in the flow direction of the resin to make four layers. Furthermore, there is also one disclosed in Japanese Patent Publication No. 50-6860.

(Problems to be Solved by the Invention) However, among the conventional multilayer dies described above, the former has disadvantages in that the die size is large, the structure is complex, and the die is expensive. In the latter case, although the structure is simple, the thickness accuracy of each layer of the manufactured multilayer film is poor. That is, even if the thickness accuracy of the entire multilayer film is good, there is a problem in that the thickness accuracy of each layer (the ratio of the thickness of each layer) is not necessarily uniform as will be described later.

In other words, if we explain the dynamics of a multiphase flow that includes layers of molten plastics with different viscosities, molten plastics with low viscosity generally tend to emerge near the outer wall surface during flow, and molten plastics with high viscosity tend to They tend to gather at the center of the channel. Therefore, when the cross-sectional shape of the flow path for the multiphase flow of molten plastic is rectangular, as in the multilayer die of the present invention, for example, there is a molten plastic layer a with a low viscosity on the outside, and a molten plastic layer with a low viscosity sandwiched therebetween. In cases where high melting plastic layers b overlap, even if the thickness of each layer is initially uniform, the sixth
As shown in the figure (cross-sectional view in the direction perpendicular to the flow), layer a wraps around each side of the rectangular cross section of the flow path, and the thickness of layer a becomes thicker at both ends. Even when layer a is on the inside and layer b is on the outside, the thickness of each layer differs between the center and both ends, as shown in FIG. Of course 3
When the thickness is more than 1 layer, the motion is even more complicated, and it is more complicated than when the thickness is uneven.

In this way, when extruding molten synthetic resins with different viscosities in layers, the thickness of each layer is not necessarily uniform in the width direction. In this invention, the thickness ratio of each layer is made equal, that is, as shown in FIG. 8, for example, X:X':
The object is to make it possible to adjust the widthwise distribution of the thickness of at least the outermost layer so that X″=Y:Y′:Y″=Z:Z′:Z″.

(Means for Solving the Problems) Means for solving the above problems in the present invention will be explained with reference to FIG.

The multilayer die of this invention includes a plurality of widening plates 1
a, 1b, 1c are stacked so that the stacking thickness is constant, and each widening plate 1a, 1
It is a multilayer die in which parts b and 1c can be replaced, and the die body 3 has a cavity 3f recessed therein, and a flat flow path 6 is provided between the cavity 3f and the die outlet 3e, and each widening plate has both sides 1 ', 1'' are substantially parallel planes, and each widening plate 1
Molten resin flow paths 2 are provided in a, 1b, and 1c,
After passing through the inlet channel 2a, this molten resin channel 2 is opened and widened on one side 1' of the widening plates 1a, 1b, 1c, and connected to the flat channel 6 at the outlet 2b with the same width. The formed and stacked plurality of widening plates 1
a, 1b, and 1c, at least the widening plates 1a, 1b, and 1c at both ends thereof have one side 1' facing outside to form an assembly of widening plates, forming a cavity 3f.
The width plate 1 is inserted into the widening plate 1.
A choker 15 supported in the width direction (direction perpendicular to the plane of the paper in FIG. 1) is provided in the cavity 3f facing the widened flow path on one side 1' of the tubes a and 1c. The widening plates 1a, 1b,
Converter 8 communicating with each inlet flow path 2a of 1c
will be established.

(effect) Next, the operation of the above means will be described.

First, the multilayer die of the present invention has widening plates 1a, 1b, 1 between the cavity 3f of the die body 3.
Even if the thickness dimensional accuracy of these widening plates is somewhat poor, as long as the flatness of both surfaces 1' and 1'' is good, these contact surfaces will come into close contact with each other without any gaps.

In order to manufacture a multilayer film using the multilayer die of the present invention assembled in this way, various molten synthetic resins are first passed through the converter 8,
Each widening plate 1a, 1b, 1c separately.
into the inlet channel 2a of the channel 2. These various types of molten synthetic resins are widened at the outlet 2b on the downstream side of the flow path 2, that is, become a flat flow spread laterally. This flat flow is laminated in a flat channel 6 formed in the die body 3 and extruded as a multilayer film. At this time, as mentioned above, since the widening plates are assembled without any gaps between them, the molten synthetic resin pumped through each channel 2 will not leak or mix, and the quality of the resulting multilayer film will be high. Very good condition.

Further, among the widening plates 1a, 1b, and 1c, at least the widening plates 1a and 1c at both ends thereof
By adjusting the width in the thickness direction of the widened channel by adjusting the curvature of the choker 15 supported in the width direction (see Fig. 3). , at least the flow resistance of the flow path in the outermost layer is changed at the center and at the ends,
By changing the flow rate accordingly, less film is extruded from this multilayer die, and the thickness accuracy in the lateral direction of the outer layer can be improved, and the thickness accuracy of the inner layer can also be improved.

(Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

1a, 1b, and 1c are widening plates that are each formed to have the same shape (the outer dimensions are the same, and the shapes and dimensions of the flow paths described later are also substantially the same). Plate 1 below
Although a will be explained, it should be understood that the same applies to the other 1b and 1c. A flow path 2 is bored in the plate 1a. The cross-sectional shape of the inlet side (left side in FIGS. 1 and 2) 2a of the flow path 2 is circular.
The downstream side (right side in FIGS. 1 and 2) 2b of the flow path 2 is formed as an open groove-like recess on one side 1' (top surface in FIG. 1) of the plate 1a. The downstream side 2b is as shown in FIG.
It is expanded in the width direction (vertical direction in FIG. 2) and formed flat.

3 is a die body. The die body 3 includes an upper side (upper side in FIG. 1) 3a, a lower side (lower side in FIG. 1) 3b, and a side lid 3c. The plates 1a and 1b are stacked with the open side 2b of the downstream side 2b, that is, the surface 1' facing upward in FIG. 3b and is inserted into the cavity 3f. Then, it is fastened by means of bolts 4, 4, 4, 4. Note that a dowel pin 5 is fitted between the plates for mutual positioning. Although the details are not shown, the two side covers 3c are attached to the upper side 3 by known fastening means.
The lateral sides of a and the lower side 3b are each covered.

The die body 3 has each plate 1a to 1c.
The outlet on the downstream side 2b of the flow path 2 (Figs. 1 and 2)
In the figure, a flat channel 6 that joins the right ends of each plate is bored at the joint between the upper side 3a and the lower side 3b. A flexible lip 7 is formed on the outlet side (right end in FIG. 1) of the channel 6 on the upper side 3a, and the thickness of the outlet of the channel 6 (S shown in the figure) is adjusted by a screw means 7a to form a multilayer lip. The overall thickness of the film is adjustable.

8 is a converter, plates 1a to 1
Attach each plate to c with two bolts 9, 9, and then tighten bolts 10, 1.
These plates and converter 8 are assembled to body 3 by means 0, 10, 10.

The converter 8 has resin injection ports 11a and 11b.
is opened. Then, the uppermost and the lowermost plates 1 in FIG. 1 are branched from the injection port 11a.
an outlet 12 communicating with each inlet side 2a of a and 1c;
A flow path leading to a, 12a is bored. 13,1
3 is from the middle of the pressure inlet 11a to the outlets 12a, 12a.
This is a flow control valve installed at the branch point.
From the pressure inlet 11b, there is an outlet 12b connected to the inlet side 2a of the middle plate 1b in FIG.
A flow path is drilled leading to.

The order of explanation of each structure described above is from the important parts of the present invention, and the order of assembling this die is to attach each plate 1a to 1c to the converter 8, and then tighten both of them to the body 3. I want to be understood as something.

14 are the upper side 3a and lower side 3b of the die body 3
This is the support means provided for the yoke. The support means 14 includes a bracket 14b fixed to the die body 3 by means of a bolt 14a, a nut 14c integrally held between the bracket 14b and the die body 3, and a female screw 15a provided on the nut 14c and the choker 15, which are screwed together. It consists of a male screw 14d.

The choker 15 is fitted into widthwise grooves 3d bored inside the upper side 3a and lower side 3b of the die body 3, respectively, so as to face the recesses on the downstream side 2b of the plates 1a and 1c over the entire width. and its both ends are supported by the side lid 3c.

and the male thread 14d of the yawker support means 14.
are provided at five locations in the longitudinal direction of the choker 15 (in the width direction of the multilayer die), and the external thread 14e and internal thread 14f of the male thread 14d are slightly different in pitch. Therefore, the nut 14c is threadedly engaged with the outer thread 14e, and the female thread 15a of the choker 15 is threaded with the inner thread 1.
4f to form a known differential screw means.

Note that the choker support means 14 may be replaced with screw means other than the differential screw means or other known means.

The operation of the above embodiment will be described below.

When a certain type of molten resin is pressurized through the injection port 11a, this resin branches from the injection port 11a and flows into the valve 1.
3, 13, the flow rate is adjusted by the outlets 12a,
12a, and reach the inlet sides 2a, 2a of the top and bottom plates 1a and 1c in FIG. Further each plate 1a and 1c
It reaches the flow path 6 via the flow path 2 and the recessed portion on the downstream side 2b.

On the other hand, a different type of molten resin is press-fitted through the injection port 11b. The resin press-fitted from the injection port 11b is
It reaches the inlet side 2a of the channel 2 of the middle plate 1b in FIG. 1 via the outlet 12b, and further reaches the channel 6 via the downstream side 2b.

Thus, the resin in the flow path 6 has three layers in FIG. 1: the uppermost layer and the lowermost layer are the resin from the injection port 11a, and the resin from the injection port 11b is in between.

In this case, various resins are used for each plate 1.
Since the resin has already been expanded and flattened in the width direction in the channels 2 from a to 1c, and these flattened resins are stacked on top of each other in the body 3, the resin layer extruded from the channel 6 has good thickness accuracy. becomes.

Furthermore, adjustment of the thickness accuracy of each layer in the width direction will be explained. That is, when each male screw 14d of the choker support means 14 is turned from the outside, the choker 15 is pushed or pulled by the difference in pitch between the outer screw 14e and the inner screw 14f for each rotation of the male screw 14d, and is bent. The flow path resistance is adjusted by adjusting the width in the thickness direction at the outside in the width direction and the center part in the concave flow path on the downstream side 2b of the flow path 2, and the resin is supplied through the plate 1b. By adjusting the thickness of the resin layer fed through the plates 1a and 1c relative to the thickness of the layers, the uniformity of the thickness ratio of each layer can be adjusted during use of this multilayer die. It is.

That is, if the viscosity of the molten resin coming from the injection port 11a is low and the viscosity of the molten resin coming from the injection port 11b is high, the resin that normally passes through the widening plates 1a and 1c with a uniform thickness as described above will The layer is thick at both ends of its width at the die exit 3e, and the layer of resin that has passed through the widening plate 1b with a uniform thickness becomes thick at the center of its width at the die exit 3e.

Therefore, in this case, the central portion of the choker 15 facing the widening plates 1a and 1c is left as is, and the both end portions are given flexure by adjusting the choker support means 14, so that substantially the downstream side of the plates 1a and 1c is The passage on side 2b is made narrower in the thickness direction at both end portions in the width direction, and the lower resistance when the molten resin passes is made larger at both end portions than at the center portion in the width direction (see Figure 3). The amount of molten resin passing through the passage 2b is smaller at both ends and larger at the center, thereby making the thickness ratio of each layer uniform at the die exit 3e. Regarding the plate 1b, the amount of recess on the downstream side 2b may be made uniform, or the resin may be made uniform in the width direction by making the center part in the width direction shallower than the outer part. It will be appreciated that in any case, at least some adjustment of the thickness of the co-outer layers is necessary, and adjustment of the thickness of the inner layer is not necessarily necessary.

In the above embodiment, a three-layer die was explained.
Similarly, if the plates are stacked in multiple layers, 4
Dies with more than one layer can also be easily formed.

Furthermore, the second embodiment shown in FIG. 5 has a total of five plates. The differences between this second embodiment and the first embodiment described above will be mainly described below.

There are five plates 1d to 1h, and the outermost plates 1d and 1h are supported by a choker 15 supported by a choker support means 14 provided on the die body 3, as in the first embodiment. , the thickness of the passage in the recess on the downstream side 2b of the flow path 2 is adjustable. and plate 1
Similarly to the first embodiment, the resins d and 1h are supplied from the pressure inlet 11a, branched off, and regulated by the control valve 13. And for plates 1e and 1g, the recesses on the downstream side 2b of these channels 2 are similar to those on plates 1d and 1g.
The choker 17 is located rearward (to the left in FIG. 5) with respect to the recess on the downstream side 2b of plates 1e and 1g, and the choker 17 is also supported by the choker support means 16 in the recess on the downstream side 2b of plates 1e and 1g. being faced face to face. Of course, the choker support means 16 penetrate through the plates 1d and 1h (however, avoiding the flow path 2) and are provided at multiple locations in the width direction, and the choker support means 17 are provided in the widthwise direction perforated in the plates 1d and 1h. It is fitted into the groove 1i, and both ends are supported on the upper side 3a or lower side 3b of the die body 3.

Although the resin supply channels to the plates 1e and 1g are not shown in detail, the channels have the same structure as the pressure inlets 11a and the control valves 13 provided in the branched channels for the plates 1d and 1h. They are provided in the converter 8 at different positions in the width direction.

The structure of the recess on the downstream side 2b of the flow path 2 of the plate 1f and the resin supply flow path to the plate 1f are the same as those for the plate 1b in the first embodiment.

In this second embodiment, five layers of resin film made of three types of resin are extruded, and the thickness of the resin extruded through the plate 1f is used as a reference, and even during the extrusion operation, the thickness of the resin film is By manipulating the support means 14 and 16, the thickness of each layer, particularly the thickness distribution in the width direction, can be uniformly controlled.

In this second embodiment, of course, only for the outermost widening plates 1d and 1h,
Although a choker 15 may be provided, a choker 17 is also provided for the widening plates 1e and 1g on the inner side thereof to ensure uniform thickness of each layer.

In each of the above two embodiments of this invention,
By preparing and assembling plates with various shapes and dimensions of the flow path 2 to the cavity 3f of the die body 3 of the same size, it is possible to produce a product with uniform thickness of each layer according to the characteristics of the synthetic resin to be supplied. Moreover, by preparing plates of various thicknesses and also preparing various converters 8, products with an arbitrary number of layers can be produced. Furthermore, the plate disposed at the center may also be provided with a choker and means for supporting it.

(Effects of the Invention) The multilayer die of the present invention has the following effects.

(1) Since multiple widening plates with substantially parallel surfaces on both sides are stacked and held in the cavity space formed in the die body, the machining dimensions of the die body and widening plates, especially in the thickness direction, do not have to be very precise. In both cases, the resins in the channels formed in each widening plate do not leak and mix.

(2) Thereby, a multilayer die capable of producing a multilayer film of good quality can be provided easily and inexpensively.

(3) Furthermore, since fewer chokers are provided in the width direction facing the widened channels of the widening plates at both ends, the thickness ratio of each layer can be made uniform, and the quality of the multilayer film can be improved.

[Brief explanation of drawings]

Figures 1 to 4 all show one embodiment of the present invention, with Figure 1 being a longitudinal side view and Figure 2 being a side view of the first embodiment.
The - cross-sectional view of the figure, Figure 3 is the - of Figure 2.
The cross-sectional view and FIG. 4 are partially cross-sectional side views. FIG. 5 is a longitudinal sectional side view of another embodiment. 6 and 7 are cross-sectional views showing the flow characteristics of the multilayer resin, and FIG. 8 is a cross-sectional view for explaining the thickness ratio of the multilayer resin. 1a, 1b, 1c, 1d, 1e, 1f, 1g,
1h... widening plate, 1', 1''... both sides, 2...
... Molten resin channel, 2a... Inlet channel, 2b... Outlet, 3... Die body, 3e... Die outlet, 3f
...Cavity, 6...Flat channel, 8...Converter, 15, 17...Chiyoker.

Claims (1)

[Scope of Claims] 1. A multilayer die in which a plurality of widening plates are stacked so that the thickness is constant and each widening plate can be replaced, and a flat flow path is provided between a cavity and the die outlet. Both surfaces of the die body and each of the widening plates are substantially parallel planes, and the molten resin flow path is opened and widened on one side of the widening plate after passing through the inlet flow path, and has the same width as the flat flow path at the outlet thereof. an assembly of widening plates formed so as to be connected to the flow path, and in which the plurality of stacked widening plates are inserted into the cavity with at least the widening plates at both ends thereof having the one side facing outward; A choker supported in the width direction by the cavity facing the widened channel on one side of the widening plate at both ends; a converter communicating with the inlet channel of the plate. 2. The multilayer die according to claim 1, wherein the choker supporting means of the die body comprises a nut integral with the die body, and a male thread that is screwed into the nut and curves the choker at its tip.