JPS62240525A - Co-extrusion feed block - Google Patents

Abstract

PURPOSE:To make it possible to easily change the constitution of thicknesses and distribution of thickness by a structure wherein a feed block is divided into three parts to unitize a straightening part. CONSTITUTION:A first block 1 distributes portions of resin delivered from a plurality of extruders 6 to the respective block units. A second block 2 realizes the function to control the constitution of thicknesses of respective layers and distribution of thickness by straightening every layer through the vesting of flow resistance between the influx port and efflux port of each layer. In addition, the second block 2 is formed by combining block units for every layer 21, 22 and 23 with one another. The control of flow resistance is possible by connecting the influx port and the efflux port with a large number of through holes. A third block 3 meets respective resin layers delivered from the second block 2 so as to fusion-weld the interfaces among the layers in order to supply them to a die 5 in the form of a multi-laminar flow. The supplied double laminar flow is spread in width in the die 5 to the predetermined extrusion width and then delivered.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to coextrusion and a feed block for merging molten resin discharged from a plurality of extruders and supplying the molten resin to a coextrusion die.

(Prior art) Conventionally, a typical method for manufacturing coextruded sheets is to provide a manifold spanning the entire width of the die for each layer of resin to be supplied, expand the resin to the extrusion width, and then merge each layer. There was a multi-manifold method in which the film was discharged from the die lip, but the die structure was complicated and expensive.
There were drawbacks such as the difficulty of changing the configuration of the die when changing the number of layers or the arrangement of the resin. On the other hand, as a relatively inexpensive manufacturing method, the so-called feedblock method is widely used, in which each layer is merged in a feedblock to form a composite layer before entering the die body, and then expanded to the desired width in the die and discharged. It is being

(Problems to be Solved by the Invention) The feedblock method described above takes advantage of the property that high viscosity fluids such as molten plastic do not easily interact with each other even in multilayer flow. In order to widen the feed block, there were problems such as: - Thickness distribution in the width direction was uneven. - It was difficult to build the thickness ratio of each layer to 7210 or more.

(Another means to solve the problem) The present invention divides the feed block into three parts, and furthermore, the rectifier part (
The idea is to solve the above problems by unitizing the second block), and its gist is a coextrusion feed block installed between a plurality of extruders and a coextrusion die, (1) A first block that receives the resin discharged from each extruder, turns it into a skin shape, and supplies it to the next first block separately for each layer; (2) A seventh block that combines the block units for each layer; The resin supplied from the block is rectified for each layer, and the first block supplied to the next third block and (3) the resin supplied from the first block are merged to completely fuse each interface. A coextrusion feedblock characterized in that it consists of three blocks, a third block feeding the coextrusion die as a composite laminar flow.

The present invention will be explained below based on the accompanying drawings.

Fig. 1 is a plan sectional view showing an example of the coextrusion feedblock of the present invention in a state of one change, Fig. 2 is a side sectional view, Fig. 3 is a 1ll-Iff sectional view of Fig. 2, and gz diagram is It is a schematic perspective view which shows an example of a 2nd block.

/ is the first block, ko is '1JI2 block, 2/, 2
2.23 is each block unit, 3 is the third block, and! is a die, and 6 is an extruder.

The first block / is for distributing the resin discharged from the mantissa extruder 6 to each block unit of the first block, as shown in FIG. 1.2.

At this time, it is preferable to make the width of the outlet wider than the inlet so that the width of the resin discharged from the extruder is expanded in the first block, and the width is adjusted so that it can be easily rectified in the second block.

It functions to adjust the distribution. In addition, this second block is a block unit 2/2 for each layer as shown in Fig.
, 22, and 23, it is easy to handle when replacing. In the example shown in FIG. 3, the flow resistance is adjusted by providing a large number of through holes between the inlet and the outlet.

By changing the diameter, number, and arrangement of the through holes, the thickness of each layer can be adjusted and the thickness distribution in the width direction can be freely adjusted. For example, in the example shown in FIG. 3, the resin passing through the block unit 2/ tends to be thick at the center, the block unit 22 tends to be thin at the center, and the block unit 23 has a uniform thickness. By adjusting these tendencies, it is also easy to make the thickness distribution in the width direction uniform. Alternatively, by actively changing the thickness distribution in the width direction, a laminated sheet having two types of thickness configurations can be obtained.

It is also possible to adjust the length of the resin passage by partially bundling each through-hole. In addition, by making the through hole one wide one,
It is also possible to achieve smooth flow and prevent resins with low heat resistance from stagnation. Furthermore, as shown in the second diagram, the overlapping portion on the outlet side of the unit may be sharply finished to prevent stagnation.

As shown in Fig. 7, this second block can be constructed by fixing a loading chamber between the seventh block and the third block into which the block units 2/22 and 23 can be taken in and out individually. This is preferable because it can be replaced extremely easily.

Next, as shown in Fig. 1.2, the third block 3 has an inlet that matches the outlet of the second block λ and an outlet that matches the inlet of the die j. The discharged I fat layers merge and fuse at the interface to form a multilayer flow and are supplied to die J. The cross-sectional shape of the exit is die! It only needs to fit the inlet of the inlet, and may be circular, square, or flat. In the example shown in FIG. 1, it is preferable that the width of the resin flow is narrowed or that the angle A is within a range of 500, which causes disturbances in the thickness distribution and the like.

As the extrusion die j, a normal single layer die may be used. The multilayer flow supplied from the third block 3 is expanded to a predetermined extrusion width in the die and discharged. Then, it is cooled by a chill roll or the like, and a laminated sheet is formed.

Incidentally, if the cross-sectional area of the flow path from the extruder to the die becomes large, resin tends to stagnate, so it is preferable to suppress the rate of change in the cross-sectional area to within 10%, for example.

Further, it is preferable that the average linear velocity of each layer be made uniform in the portion where each layer joins.

(Effects of the Invention) As described above, the present invention divides the feed block into three blocks, and combines the first block for expanding the molten resin to a width that facilitates rectification, and the block units for each layer. The second one to adjust the thickness by rectifying each layer.
The block consists of a block and a third block for combining each layer to form a multilayer and supplying it to the die. It is possible to vary the thickness of each layer, and also to produce large laminated sheets with a thickness ratio of /:10.

(2) When changing the thickness configuration, thickness distribution, etc.! This can be easily done by exchanging the 8@2 blocks for each block unit.

It has a similar effect.

[Brief explanation of drawings]

FIG. 7 is a plan sectional view showing an example of a usage state of the coextrusion feedblock of the present invention, FIG. 2 is a side sectional view,
FIG. 3 is a sectional view taken along line 11-1 in FIG. 1, and FIG. Z is a schematic perspective view showing an example of the second block.

Claims (1)

[Scope of Claims] A coextrusion feed block installed between a plurality of extruders and a coextrusion die, comprising: (1) receiving and layering resin discharged from each extruder; (2) A second block that is composed of a combination of block units for each layer, rectifies the resin supplied from the first block for each layer, and supplies the resin to the next third block. (3) The resin supplied from the second block is merged to completely fuse each interface, and then the third block is supplied to the coextrusion die as a composite laminar flow. Extrusion feedblock.