JPS591179B2 - Extrusion die for multilayer film production - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides a multilayer film (
The present invention relates to an extrusion die for manufacturing (including sheets with a thickness of 0.25 mm or more).

An extrusion die for producing a multilayer film consisting of three layers includes a first distribution channel that vertically guides the first film raw material supplied from the first extruder downward, and a second film supplied from the second extruder. second and third distribution channels that guide the raw material to both sides of the first distribution channel in an opposing manner, the widths of the second and third distribution channels being different from the width of the first distribution channel; There is a known extrusion die with
(See Publication No. 59).

In the above-mentioned known extrusion die, in an unstretched multilayer film consisting of three layers, one of the front and back layers made of the same raw material and the middle layer made of another raw material is used as a wide base layer, and the other is used as a wide base layer. It is formed into a narrow composite layer (see Figures 8a and b), and stretched and heat-set by gripping either the front and back two layers at both ends in the width direction and the intermediate layer p with a chitta grip A during tenter stretching. When cutting both ends later, the first
The purpose is to obtain plant waste of a pure single synthetic resin consisting of either one of the second film raw material and the second film raw material, and to recover and utilize this plant waste. However, in the unstretched multilayer film F manufactured by the above-mentioned known extrusion die, both ends are composed of the front and back two layers q or only the intermediate layer p, and the intermediate part is composed of three layers. The thickness is different from the middle part, and the thickness changes rapidly at the boundary between both ends and the middle part, and during tenter stretching, stress is concentrated at the boundary and easily breaks, and near the boundary. However, the intermediate portion of the final product is insufficiently and non-uniformly stretched, making it difficult to obtain desired properties.

Therefore, when stretching with a tenter, it is actually necessary to grip the middle part of the three layers near the end with a chitta grip, and in this case, the cuttings are mixed into the mixture of the first and second film raw materials. As this is unavoidable, the original purpose of collecting and reusing crop waste cannot be fully achieved. In addition, since the extrusion die described above forms the width of the composite layer narrower than the base layer by narrowing the width of the distribution channel for the composite layer, the type of film raw material, the extrusion die and When changing the width of the composite layer depending on the draft ratio between the cooling roll and the tenter stretching ratio, etc., the extrusion die must be disassembled and parts replaced, making the above changes extremely time consuming. In addition to being cumbersome, it also had the disadvantage of requiring a large number of parts to be stored. ≦On the other hand, in the convergence conduit below the confluence point of the above distribution conduits, the film raw material for the base layer is flowed into both the left and right sides of the composite layer to make the thickness of the entire multilayer film uniform in the width direction, so that both ends are uniform. An extrusion die made of a single synthetic resin is known (see Japanese Utility Model Application No. 52-121460).

However, in this known extrusion die, the gap in the thickness direction of the upper half of the merging conduit is narrowed at both ends and widened in the middle, and the gap in the lower half is widened across the entire width of the upper half. Since the film material for the base layer is not newly supplied to both ends, the film material for the pace layer is not sufficiently distributed to the left and right sides of the composite layer, and as a result, the resulting multilayer film Similar to the multilayer film manufactured by the extrusion die described in the above-mentioned Japanese Utility Model Publication No. 52-37659, both ends are formed to be thinner than the middle part, and film breakage and uneven stretching occur during tenter stretching of the multilayer film. In some cases, it may become impossible to collect and reuse planting waste. When changing the width of the composite layer, the same difficulty as described above is encountered.This invention provides a method for removing crop waste by supplying film raw material for the base layer to both ends of a manifold for the composite layer. A multilayer film (see Fig. 8A, b) in which both ends are made of a single synthetic resin and has a uniform thickness over the entire width can be obtained, and the width of the composite layer can be easily changed. It is something.

That is, this invention includes two or more distribution channels each consisting of a manifold and a narrow passage following the manifold, and the lower ends of the distribution channels are respectively connected to the upper ends of the merging channel, so that the lower end of the merging channel is discharged. In an extrusion die for producing a multilayer film in which the multilayer film is extruded through a slit, the distribution channel and the merging channel are formed to have substantially the same width, and the intermediate portion of the manifold for the composite layer is This is an extrusion die for producing a multilayer film, characterized in that a raw material introduction channel for the composite layer is opened, and auxiliary introduction channels are opened at both ends, through which film raw materials for the base layer are supplied.
A first embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

In this first embodiment, as shown in FIG. 7a, the intermediate layer p is a base layer, the surface layer q and the back layer r are composite layers made of the same film raw material, and both ends are the layers of the intermediate layer p. This is an extrusion die for producing a multilayer film Pa formed only from film raw materials. In FIGS. 1 and 2, the extrusion die 1 includes a coupling adapter 2, a front body 3 and a rear body 4 in contact with the lower surface of the coupling adapter 2, a fixing lip 5 in contact with the lower surface of the front body 3, and the rear body 4. The L-shaped coupling fitting 6 is in contact with the lower surface, the beam-shaped coupling fitting 7 is in contact with the inside of the L-shaped coupling fitting 6, the adjustment lip 8 is in contact with the lower surface of the beam-shaped coupling fitting 7, and a large number of left and right side plates 9, 9 are connected. are integrally connected with bolts (not shown),
A heater (not shown) for heat retention is installed around it.

At the respective joints of the members of the front main body 3 or the adjustment lip 8, excluding the above-mentioned coupling adapter 2 and side plates 9, 9,
A first distribution conduit 10 consisting of a first manifold 10a and a first slit passage 10b, a second distribution conduit 11 consisting of a second manifold 11a and a second slit passage 11b, a third manifold 12a and a third slit passage 11b; A third distribution conduit 12 consisting of a gap passage 12b, a confluence gap passage 13a1 and a pressure equalization chamber 1
3b and a discharge slit 13c at the lower end.
are cut across the entire width, and the opening ends in the width direction are closed by the side plates 9, 9. As shown in FIG. 3, the above-mentioned coupling adapter 2, front body 3, etc. are connected to a first introduction path 14 that communicates the central part of the first manifold 10a with a first extruder (not shown) K. and the first
Auxiliary introduction paths 14a, 14b, and 14c branch from the introduction path 14 and communicate with both ends of the second manifold 11a and third manifold 12a, and the central portions of the second manifold 11a and third manifold 12a are connected to the second extruder. A communicating second introduction path 15 is formed respectively. The above-mentioned auxiliary introduction path 14 communicating with the third manifold 12a
b and 14c are bored in the rear main body 4 and side plate 9, as shown in FIG.
, 14c is connected to the valve body 1 buried in the rear body 4.
6 and a valve rod 17 passing through a side plate 9.
8 is provided. The threaded portion 17a at the outer end of the valve stem 17 is screwed into a screw hole in the outer plate 19 fixed to the side plate 9, and its rotation causes the flow control valve 18 to open. The opening degree is adjusted. Note that the same flow rate control valve 18 as described above is also provided in the auxiliary introduction passages 14b and 14c communicating with the second manifold 11a. On the other hand, as shown in FIG. 1, a widthwise long chain yoke 20 is provided in the merging conduit 13 so as to be able to slide back and forth. Converging slit passage 1
Further, the tip of an adjustment bolt 22 is threaded into the adjustment lip 8, and the rotation of the adjustment bolt 22 adjusts the gap between the discharge slots 13c. In the above structure, when the first film raw material is supplied to the first introduction passage 14 and the second film raw material is supplied to the second introduction passage 15, the first film raw material is supplied to the first manifold 10.
a, and both ends of the second manifold 11a and the third manifold 12a, respectively, and the second film raw material is introduced into the second manifold 11a and the third manifold 1.
2a, so the discharge slit 13
The multilayer film Pa shown in FIG. 7a is discharged from c. By adjusting the discharge amount of the first extruder and the second extruder and the opening degree of the flow rate control valve 18, the width T of the surface layer q and the back surface layer r forming the composite layer, in other words, the width of the multilayer film Pa is adjusted.
The width t of both ends made of only the first film material for the base layer can be set arbitrarily. Next, the seventh
A second embodiment for manufacturing the multilayer film Pb shown in FIG. 4 will be described with reference to FIG.

The above-mentioned coupling adapter 2, front body 3, etc. are provided with a first introduction path 14 that communicates the center portion of the first manifold 10a with the first extruder, and a second introduction path 14 that communicates the center portion of the second manifold 11a and the third manifold 12a with the first extruder. Second introduction path 1 communicating with the extruder
5, and auxiliary introduction passages 15a and 15 that branch from the second introduction passage 15 and communicate with both ends of the first manifold 10a.
b is formed, and a flow control valve 18 is provided at the connection portion of the auxiliary introduction passages 15a and 15b as in the first embodiment.
In the above structure, when the first film raw material is supplied to the first introduction passage 14 and the second film raw material is supplied to the second introduction passage 15, the first film raw material is supplied to the first manifold 1.
0a, and the second film raw material is introduced into both ends of the first manifold 10a and the middle parts of the second manifold 11a and the third manifold 12a, so that the second film material is introduced from the discharge slit 13c into the second film material. A multilayer film Pb shown in FIG. 7b having the film raw material as a base layer is discharged. Next, a third embodiment in which the position of the auxiliary introduction path of the first embodiment is changed will be described with reference to FIGS. 5 and 6. Fifth
In the figure, a first introduction path 14 communicating the center part of the first manifold 10a with the first extruder, and a second manifold 1
1a and a second introduction path 15 that communicates the central portions of the third manifold 12a with the second extruder are formed in the same manner as in the first and second embodiments. On the other hand, the first to third manifolds 10
The end faces of a, 11a, and 12a are communicated with each other through auxiliary introduction passages 20a, 20b, and 20c cut into the side plate 9,
A flow control valve 18 is provided at the connection between the auxiliary introduction passages 20b and 20c.
will be provided. As shown in FIG. 6, the flow rate control valve 18 consists of a valve body 16 embedded in the inner surface of the side plate 9 and a valve stem 17 protruding outward from the side plate 9. The valve stem 17 has a threaded portion 17a. is screwed into a screw hole in the outer plate 19 fixed to the outer surface of the side plate 9. Note that the auxiliary introduction passage 20c in FIG. 5 is provided inside the valve body 16. In the above structure, the first film material is introduced into the first introduction path 14 and the second film material is introduced into the second introduction path 1.
When the second film raw materials are respectively introduced into the first manifold 10a and the discharge amounts of the first and second extruders and the opening degree of the flow rate control valve 18 are set appropriately, the second film raw materials introduced into the center of the first manifold 10a are One film raw material is passed from both ends of the first manifold 10a to auxiliary introduction passages 20a, 20b1 flow rate control valve 18
, the second and third manifolds 11 through the auxiliary introduction path 20c.
The multilayer film Pa shown in FIG. 7a is introduced into both ends of the film a and 12a and is discharged from the discharge slit 13c. In this third embodiment, when the discharge rate of the first extruder is decreased and the discharge rate of the second extruder is increased, the auxiliary introduction passages 20a, 20b, 2
The flow direction of the film raw material at 0c is reversed, and the second film raw material is introduced from both ends of the second manifold 11a and the third manifold 12a to both ends of the first manifold 10a, so that the multilayer film Pb of FIG. 7b is manufactured. In the first to third embodiments described above, the intermediate layer p is the first film raw material, and the surface layer p and the back layer r are the second film raw material.
This is an extrusion die for manufacturing a three-layer film made of film raw materials, but when the width of the intermediate layer p is widened and the intermediate layer p is used as a base layer as shown in FIG. 7a, the second manifold 11a and the third manifold The surface layer q and the back layer r can be formed using different film raw materials by communicating a second extruder with one of the extruders 12a and a third extruder with the other.

When the intermediate layer p, the surface layer q, and the back layer r are formed using different film raw materials, one of the film raw materials for the front layer q and the back layer r is supplied to the end of each manifold to form a multilayer layer. The end portion of the film can be formed using only one of the above film raw materials. Further, in the above embodiment, the auxiliary introduction paths 14c, 15b, 20a, 20c
is provided on the side plate 9 and opened at the end face of the manifold, but it may also be provided on the front main body 3, rear main body 4, etc. and opened perpendicular to the manifold. Furthermore, in each of the above embodiments, by increasing or decreasing the number of distribution channels, it is possible to manufacture a multilayer film having two or more layers.
A choke cover similar to the choke cover 20 of the confluence narrow passage 13a can be provided in the third narrow passage 12b. It goes without saying that other design changes can be made as appropriate within the scope of the present invention. As explained above, in this invention, the film raw material for the base layer is supplied to both ends of the manifold for the composite layer through the auxiliary introduction passage, so that the total thickness is uniform in the width direction. , it is possible to produce a multilayer film with both ends made of a single film raw material, and when changing the width of both ends, it is only necessary to adjust the flow rate of the film raw material, and the extrusion die can be disassembled and parts replaced. Therefore, when the film raw material is changed, the optimum width of both ends can be easily set.
In the multilayer film manufactured by the extrusion die of this invention, both ends are made of a single film raw material and the total thickness is uniform, so there is no possibility of uneven stretching or film breakage during tenter stretching. Therefore, a high-quality stretched film can be obtained, and the waste from both ends can be recovered and used as a film raw material for the base layer.

[Brief explanation of drawings]

FIG. 1 is a vertically sectioned side view of the first embodiment of the present invention;
The figures are a front view cut perpendicularly to the - line in Fig. 1, Fig. 3 is a perspective view of the channel through which the film raw material passes in the first embodiment, Fig. 4 is a perspective view of the channel in the second embodiment, and Fig. 5. is a perspective view of the flow path of the third embodiment, FIG. 6 is a plan view of the main part of the third embodiment, which corresponds to the plan view cut horizontally along the - line in FIG. 1, and FIG. 7 is a diagram showing the extrusion die of the present invention. A vertical sectional view in the width direction of the multilayer film thus produced, and FIG. 8 is a vertical sectional view of a conventional multilayer film. 10a, 11a, 12a... Manifold, 1
0b, 11b, 12b... Slit passage, 10, 1
1, 12... Distribution guideway, 13... Merging guideway, 13c... Discharge slit, 14...
First introduction path, 15...Second introduction path, 14a, 1
4b, 14c, 15a, 15b, 20a, 20b, 20
c...Auxiliary introduction path.

Claims (1)

[Scope of Claims] 1. Two or more distribution channels each consisting of a manifold and a narrow passageway following the manifold, the lower ends of the distribution channels being connected to the upper ends of the merging channel, respectively, so that the lower end of the merging channel is connected to the lower end of the merging channel. In an extrusion die for producing a multilayer film in which the multilayer film is extruded from the discharge slit of An extrusion die for producing a multilayer film, characterized in that a raw material introduction passage for the composite layer is opened at the opening, and auxiliary introduction passages for supplying the film raw material for the base layer are opened at both ends. 2. The extrusion die for producing a multilayer film according to claim 1, wherein the auxiliary introduction path is branched from the base layer introduction path connected to the center of the base layer manifold. 3. The extrusion die for producing a multilayer film according to claim 1, wherein the auxiliary introduction path connects both ends of the base layer manifold and the composite layer manifold. 4. The extrusion die for producing a multilayer film according to any one of claims 1 to 3, wherein the auxiliary introduction path is equipped with a flow rate control valve.