JP2018126893A - Extrusion film formation die head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress occurence of neck-in, and to suppress decrease in strength on an end part side of a film.SOLUTION: There is provided an extrusion film formation die head for forming a molten resin into a film via supplying of the molten resin, the die comprising: a first part possessing a passage for circulating the molten resin, which is provided at an upper stream end of the die head; a second part for circulating the molten resin in a passage whose width is wider than that of the passage in the first part, which is provided at a lower stream end of the die head; and a third part possessing a passage connecting the passage in the first part with the passage in the second part, which is provided between the first part and the second part, for circulating the molten resin from the first part to the second part. Passage widths of the first part and the second part each remain constant, and the passage in the third part continuously becomes wider in width as the foregoing the passage comes closer toward the lower stream end from the upper stream end.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a die head used for extrusion film formation.

  Generally, in extrusion film formation, a resin film is produced by extruding a molten resin from a die head in a state of being formed into a film and cooling it with a cooling roll. Patent Document 1 discloses a die head used for film formation. In this die head, molten resin is supplied to the manifold, passes through a slot provided in the downstream portion of the manifold, and is formed into a film shape. The die head has a first inner deckle and a first inner deckle that are in contact with and guide the molten resin passing through at both ends in the width direction of the manifold and the slot. The second inner deckle is disposed downstream of the first inner deckle. The surface in contact with the molten resin of the second inner deckle is inclined or curved so as to widen the dimension in the width direction of the lower end portion of the slot.

JP 2011-213083 A

  Here, in extrusion film formation, there is a phenomenon in which the film width called “neck-in” shrinks in the idle running section (gap) until the molten resin film extruded from the die head is cooled by the cooling roll. Occur. Patent Document 1 states that neck-in can be suppressed by inclining or curving the surface of the second inner deckle in contact with the molten resin so as to widen the widthwise dimension of the lower end of the slot. Yes. This is because the size in the width direction of the lower end of the slot is widened to suppress the difference in the flow rate (flow rate) of the molten resin between the end in the width direction and the center. It is considered that the difference in film thickness on the end side with respect to the film thickness can be reduced. However, even in the region widened by the inclination or curvature of the lower end portion of the slot, the flow rate of the molten resin becomes slower toward the end portion, so that the flow path decreases as the flow rate decreases, and the film thickness decreases. Thus, there is a problem that the strength on the end side of the film is lowered. Therefore, there is a demand for a technique that can suppress the occurrence of neck-in and can suppress a decrease in strength on the end side of the film.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) According to one aspect of the present invention, there is provided an extrusion film-forming die head that is supplied with a molten resin and molded into a film shape. This extrusion film-forming die head is provided at the upstream end of the die head and has a first part having a flow path for circulating the molten resin; provided at the downstream end of the die head, and more than the flow path of the first part. A second portion for allowing the molten resin to flow through a wide flow path; and provided between the first portion and the second portion, the flow path of the first portion and the flow path of the second portion. And a third portion that has a flow path to be connected and distributes the molten resin from the first portion to the second portion. The width of the flow path of the first part and the second part is constant, and the width of the flow path of the third part continuously increases from the upstream end toward the downstream end.
According to the extrusion film-forming die head of this aspect, in the portion of the flow passage of the second portion outside the width direction from the flow passage of the first portion, it extends from the central portion side to the end portion side in the width direction of the flow passage. Thus, the degree of decrease in the flow rate of the molten resin can be suppressed. Thereby, the difference of the film thickness from the center part side to the edge part side of the formed film can be suppressed, and a decrease in strength on the edge part side of the film can be suppressed. As a result, it is possible to suppress the occurrence of neck-in and to suppress the decrease in strength on the end side of the film.

  In addition, this invention can be implement | achieved in various aspects, for example, can be implement | achieved in aspects, such as a film forming apparatus using the die head for extrusion film formation, and the die head for extrusion film formation.

The schematic perspective view which shows the structure of the die head used for extrusion film forming. II-II arrow sectional drawing of the die head of FIG. The front view which shows the flow path of a manifold, and the flow path of an opening part. The enlarged view of the structure of the part of FIG. The enlarged view which shows the structure of the comparative example corresponding to the part of FIG. The graph which shows an example which compared the relationship between the neck-in amount of a resin film, and the thickness of the edge part of a resin film with embodiment and the comparative example, 2. FIG. Explanatory drawing which shows a problem when the thickness of the edge part of a resin film becomes thin. The graph which shows an example which compared the relationship between the position of the width direction of an opening end, and the flow velocity of molten resin with embodiment and the comparative example. The enlarged view which shows the comparative example of a structure different from the comparative example of FIG. Explanatory drawing which shows the setting effect of a breadth. Explanatory drawing which shows the setting effect of an inclination angle. Explanatory drawing which shows the setting effect of opening edge height.

A. Embodiment:
FIG. 1 is a schematic perspective view showing a configuration of a die head 10 used for extrusion film formation. FIG. 2 is a cross-sectional view of the die head 10 of FIG. X, Y, and Z shown in FIGS. 1 and 2 indicate directions orthogonal to each other. Y indicates the vertical direction, and X and Z indicate the horizontal direction. Below, the width direction of the die head 10 corresponding to the width direction of the resin film molded by the die head 10 will be described as the X direction, the height direction as the Y direction, and the depth direction as the Z direction.

  As shown in FIGS. 1 and 2, the die head 10 includes a first die 110, a second die 120 disposed to face the first die 110 along the Z direction, and the first die 110 and the second die. And a shim 130 sandwiched between 120 and 120. As shown in FIG. 2, the facing surface 112 of the first die 110, the facing surface 122 of the second die 120, and the shim 130 include the manifold 11 and the opening 12 provided on the lower end side in the Y direction of the manifold 11. Configure.

  As shown in FIG. 2, molten resin MR is supplied to the manifold 11 from an extruder (not shown) through a supply port 115 and a supply hole 116 provided in the first die 110. The molten resin MR is obtained by melting a resin for film formation. The first die 110 and the second die 120 are provided with a heater (not shown), and the temperature is kept by the heater so that the molten resin MR supplied to the manifold 11 is kept in a molten state. ing.

  The molten resin MR supplied to the manifold 11 flows through the flow path of the manifold 11 and is supplied to the opening 12. The molten resin MR supplied to the opening 12 flows through the flow path of the opening 12 and is pushed downward (Y direction) in a state of being formed into a film shape from the opening end 13 that is the downstream end of the opening 12. It is. That is, the die head 10 is an apparatus that molds and melts the molten resin MR supplied from the extruder into a film shape. In addition, the thickness of the opening of the opening end 13, that is, the thickness of the shim 130 is set to an appropriate thickness according to the thickness of the resin film formed by the extruded molten resin MR. However, since the pressure inside the manifold 11 increases as the thickness of the shim 130 decreases, and the pressure tends to decrease as the thickness of the shim 130 increases, an optimum thickness is selected based on the characteristics of the molten resin MR, the die temperature, and the like. Is preferred.

  As shown in FIG. 1, a cooling roll 20 is disposed below the die head 10. In the die head 10, the molten resin MR in a state of being formed into a film is pushed out from the opening end 13 (FIG. 2) and flows down toward the cooling roll 20. The molten resin MR that has flowed down contacts the roll surface of the cooling roll 20, moves in accordance with the rotation of the cooling roll 20, and is cooled and solidified until it leaves the roll surface and is carried out in the transport direction. Thereby, the resin film WS is produced. A broken line portion in FIG. 1 indicates a portion where the molten resin MR contacts the cooling roll 20. The die head 10 can be used for extrusion film formation of various resin films such as electrolyte film formation.

  FIG. 3 is a front view showing the flow path of the manifold 11 and the flow path of the opening 12. FIG. 3 shows a state in which the inside of the die head 10 is transmitted from the second die 120 side and the shim 130 and the facing surface 112 of the first die 110 are shown.

  The shim 130 (shown with hatching in the figure) has a frame shape with an open lower end, and an area inside the frame is an upper area 131 corresponding to the manifold 11 and a lower area corresponding to the opening 12. 132. The upper region 131 forms a flow path of the manifold 11 together with the groove portion 124 (FIG. 2) provided on the facing surface 122 of the second die 120. The lower region 132 constitutes the flow path of the opening 12. The molten resin MR supplied to the manifold 11 (lower region 132) from the supply hole 116 flows through the flow path of the manifold and the flow path of the opening 12 (lower region 132), and the open end 13 (see FIG. From 2), it is extruded in a state of being formed into a film.

  The width of the upper region 131 corresponds to the width of the flow path of the manifold 11 and is constant. The width Wm of the upper region 131 is a distance (a distance along the X direction) between the inner side walls 138 of the frame of the shim 130. The width of the upstream end of the lower region 132, that is, the width of the upstream end of the flow path of the opening 12 is equal to the width Wm of the upper region 131. The flow path of the opening 12 is connected to the flow path of the manifold 11. On the other hand, the width Wo of the downstream end of the lower region 132, that is, the downstream end of the flow path of the opening 12, that is, the width of the open end 13 (FIG. 2) is the width Wm of the upstream end of the lower region 132. Is wider than. Specifically, the positions of the side walls 138 on both sides in the width direction at the downstream end of the lower region 132 are respectively wider than the positions of the side walls 138 on both sides at the upstream end of the lower region 132 by Wo = (Wm + 2 · Wc). ).

  FIG. 4 is an enlarged view of the structure of the portion Ae in FIG. The lower region 132 is divided into an opening end region 134 and an opening inclined region 133 on the downstream side. The opening 12 uses the upstream inclined region 133 as a flow path, the open inclined portion 12a connected to the flow path of the manifold 11 and the downstream open end region 134 as a flow path, and the flow of the open inclined portion 12a. It is divided into an open end 12b connected to the road. In the following, the inclination angle of the side walls 138 on both sides in the width direction of the opening inclined region 133 is θc, the spread width in the width direction (X direction) of the region due to the inclination is Wc, and the direction perpendicular to the width direction of the opening inclined region ( The height in the Y direction (hereinafter also referred to as “inclination height”) is defined as Hc. Further, the flow path of the opening end portion 12b, that is, the height (hereinafter also referred to as “opening end height”) in the direction (Y direction) perpendicular to the width direction (X direction) of the opening end region 134 is referred to as Hs. .

  FIG. 5 is an enlarged view showing the structure of a comparative example corresponding to the portion Ae of FIG. The opening portion 12Ra of the comparative example has a structure in which the opening end portion 12b of the opening portion 12 in FIG.

Below, the result of comparing the embodiment of FIG. 4 with Comparative Examples 1, 2, and 3 based on FIG. 5 will be described. However, the inclination angle θc, the spreading width Wc, the inclination height Hc and the opening end height Hs of the embodiment, and the inclination angle θc, the spreading width Wc, and the inclination height Hc of Comparative Examples 1, 2, and 3, respectively, Assume that the settings are as follows.
Embodiment: θc = θ0 (> 0) [°], Wc = W0 [mm], Hc = hc0 (= W0 / tan θ0) [mm], Hs = hs0 [mm]
Comparative example 1: θc = 0 °, Wc = 0 mm
Comparative Example 2: θc = θ0 [°], Wc = W0 / 2 [mm], Hc = hc0 / 2 [mm]
Comparative Example 3: θc = θ0 [°], Wc = W0 [mm], Hc = hc0 [mm]
Comparative Example 1 shows a case where the flow path of the opening 12Ra is equal to the width of the flow path of the manifold 11. Comparative Example 2 shows a case where the spread width Wc and the inclination height Hc are ½ as compared with the embodiment and Comparative Example 3.

  FIG. 6 is a graph showing an example in which the relationship between the neck-in amount of the resin film and the thickness (end height) of the end of the resin film is compared between the embodiment and Comparative Examples 1, 2, and 3. The neck-in amount is represented by the contraction amount of the end portion in the width direction on one side with respect to the width of the opening end 13. As compared with Comparative Example 1, as shown in Comparative Examples 2 and 3, the effect of reducing the neck-in amount can be obtained by increasing the spreading width Wc. However, since the thickness (end height) of the end portion of the resin film is reduced by increasing the spreading width Wc, the problem described below may occur in the comparative example 3.

  FIG. 7 is an explanatory diagram showing a problem when the thickness of the end portion of the resin film is reduced. Since the end portion of the resin film at the time of being pushed out from the opening end 13 is thinned, the end portion in the width direction of the resin film is weakened in strength. Therefore, the manufactured resin film WS has the portion AR. The part which tears and cuts like this occurs.

  FIG. 8 is a graph showing an example in which the relationship between the position in the width direction of the opening end 13 (opening end position) and the flow velocity of the molten resin MR is compared between the embodiment and Comparative Examples 1, 2, and 3. As shown in FIG. 8, in the case of the comparative example 1, the flow rate corresponding to the flow rate of the molten resin MR rapidly decreases at the end in the width direction (position indicated by the alternate long and short dash line). (Film thickness) is substantially uniform up to the position where the flow velocity (flow rate) suddenly decreases, and becomes thinner on the end side than that.

  On the other hand, in the case of Comparative Examples 2 and 3, the molten resin MR is supplied to the outside of the end portion in the case of Comparative Example 1 according to the expansion of the flow path according to the inclination angle θc (= θ0). And flows out from the open end 13 (FIG. 3). However, in the case of Comparative Examples 2 and 3, the flow velocity (flow rate) of the molten resin MR at the opening end 13 is directed toward the end side according to the spread of the flow path according to the inclination angle θc (= θ0). It will fall slowly. As the flow rate (flow rate) changes, the film thickness decreases toward the end.

  Here, the change in the flow velocity (flow rate) is gentler in Comparative Example 3 than in Comparative Example 2. For this reason, as shown in FIG. 6, the flow rate (flow rate) is larger in the same position in the width direction of the opening end 13 in the comparative example 3 than in the comparative example 2, that is, the wider spreading width Wc. The neck-in amount becomes smaller. However, since the spread width Wc is larger in the comparative example 3 than in the comparative example 2, it is considered that the width in which the film thickness becomes thinner becomes wider and the end portion becomes weak in strength as described above.

  Therefore, in the embodiment (FIGS. 3 and 4), the flow path has an opening end portion 12b having a constant width Wo downstream of the opening inclined portion 12a extending from the width Wm to the width Wo. Accordingly, in the embodiment, as shown in FIG. 8, it is possible to suppress the decrease in the flow rate (flow rate) of the molten resin MR up to the end in the width direction of the opening end 13, and thus suppress the decrease in the film thickness. be able to. As a result, in the embodiment, as shown in FIG. 6, the neck-in amount is suppressed to be equal to that in Comparative Example 3, and the decrease in the film thickness at the end is suppressed, so that the strength on the end side of the resin film is reduced. The decrease can be suppressed. Moreover, in this embodiment, it is the structure which expands only the width | variety of the flow path of the opening part 12, without changing the external shape of the shim 130. FIG. For this reason, it can be easily realized only by changing the shape inside the shim without changing the size of the die head composed of a pair of dies and shims.

  As the shape of the shim 130, the interval between the side walls 138 on both sides is expanded to a uniform size, and the widths of all the flow paths of the manifold 11 and the opening 12 are expanded uniformly, as in the embodiment. In addition to suppressing the neck-in amount, it is possible to suppress a decrease in the film thickness at the end portion, thereby suppressing a decrease in strength on the end portion side of the resin film. However, in this case, it is inconvenient because the width of the groove portion 124 of the second die 120 of the pair of dies 110 and 120 sandwiching the shim 130 needs to be changed along with the change of the shape of the shim 130. Moreover, the sealing property of the molten resin MR in the manifold 11 may be reduced. On the other hand, in the embodiment, it is possible to realize it by changing only the inner shape of the shim 130 without changing the structure of the pair of dies 110 and 120.

  Further, by enlarging the entire die head and uniformly widening the entire flow path of the manifold 11 and the opening 12, the sealing performance of the molten resin MR in the manifold 11 is not lowered, and the same as in the embodiment. In addition, the neck-in amount can be suppressed, and the decrease in the film thickness at the end can be suppressed to suppress the decrease in the strength on the end side of the resin film. However, this is inconvenient because the structure of the entire die head must be changed. In addition, when the die head is large, the size of the opening at the opening end becomes thicker at the center than at the end due to the pressure of the molten resin MR flowing in the flow path, and the film thickness at the center tends to increase. In order to solve this problem, an adjustment bolt that adjusts the size of the opening at the opening end of the die head for each position in the width direction is generally used to make the film thickness uniform. In the present embodiment, this problem can be suppressed, and the labor for adjusting the film thickness can be reduced. Further, the adjustment can be omitted when the tolerance range of the dimension required for the film thickness is large.

  FIG. 9 is an enlarged view showing a comparative example having a structure different from that of the comparative example of FIG. FIG. 9 shows a structure corresponding to the portion Ae of FIG. The comparative example 5 has an opening 12Rb having a structure corresponding to the die head described in the prior art. Whereas the portion of the side wall 138 of the opening inclined portion 12a constituting the opening 12Ra of Comparative Examples 2 and 3 (FIG. 5) is a plane inclined at a constant inclination angle θc, the opening 12Rb of Comparative Example 5 is The portion of the side wall 138 corresponding to the opening inclined portion 12a is a curved surface. Also in the opening 12Rb of the curved surface, the characteristics of the flow rate of the molten resin MR at the opening end 13 (FIG. 8) and the relationship between the film thickness on the end side of the opening end 13 and the neck-in amount (FIG. 7) are compared. This is considered to be the same as in the case of the opening inclined portion 12a of the opening 12Ra in Examples 2 and 3. Therefore, the embodiment can suppress the decrease in the flow rate (flow rate) of the molten resin MR up to the end portion in the width direction of the opening end 13 as compared with the comparative example 5, while suppressing the neck-in amount and the end. It is possible to suppress a decrease in strength at the end portion side of the resin film by suppressing a decrease in the film thickness of the portion.

  Further, Comparative Example 5 has a structure in which the molten resin MR tends to stay in the recessed corner portion Pc. On the other hand, the embodiment is advantageous in comparison with Comparative Example 5 in that it has a shape without the recessed corner portion Pc as in Comparative Example 5 (FIG. 4) and has a structure in which the molten resin MR hardly stays. is there.

  In the embodiment, the inclination angle θc of the opening inclined portion 12a, the spreading width Wc, the inclination height Hc, and the opening end height Hs (FIG. 4) of the opening end portion 12b are described below. Can be set.

  FIG. 10 is an explanatory diagram showing the effect of setting the spread width Wc. FIG. 10 is a graph showing changes in the flow rate of the molten resin MR at the opening end 13 due to changes in the spreading width Wc. However, the inclination angle θc is constant and the opening end height Hs = 0 (FIGS. 4 and 5). As shown in FIG. 10, the flow rate (flow velocity) of the molten resin MR gradually decreases smoothly toward the end. However, as the spreading width Wc increases, the position of the end of the opening end 13 (the position indicated by the alternate long and short dash line) increases accordingly, the width of the opening end 13 increases, and the width of the region through which the molten resin MR flows increases. In addition, as the spread width Wc increases, the inclination height Hc (= Wc / tan θc) increases, so that the flow rate flowing into the flow path on the end side corresponding to the spread width Wc increases, and the flow rate on the central portion side increases. Decrease. Thereby, the resin film before the neck-in which is pushed out from the opening end 13 is generated has a thin film thickness at the central portion and can widen the film width. That is, by adjusting the spread width Wc, the film thickness and the film width can be adjusted. However, as described in Comparative Examples 2 and 3 above (FIGS. 6, 7, and 8), as the spread width Wc is increased, the film thickness on the end side becomes thinner and the end side of the film is weaker in strength. There is a problem of becoming.

  FIG. 11 is an explanatory diagram showing the effect of setting the inclination angle θc. FIG. 11 is a graph showing changes in the flow rate of the molten resin MR at the opening end 13 due to changes in the inclination angle θc. However, the spread width Wc is constant and the opening end height Hs = 0. As shown in FIG. 11, as the inclination angle θc decreases, the inclination height Hc (= Wc / tan θc) increases, so that the flow rate flowing into the end-side flow path corresponding to the spread width Wc increases, The flow rate on the part side decreases. Thus, the film thickness on the end side can be increased by reducing the inclination angle θc. However, reducing the inclination angle θc while keeping the spread width Wc constant leads to an increase in the outer dimension of the shim, resulting in an increase in the size of the entire die head.

  FIG. 12 is an explanatory diagram showing the effect of setting the opening end height Hs. FIG. 12 is a graph showing changes in the flow rate of the molten resin MR at the opening end 13 due to changes in the opening end height Hs. However, the spreading width Wc and the inclination height Hc are constant. As shown in FIG. 12, when the opening end height Hs is provided, the flow rate to the end of the opening end 13 is compared with the case where the opening end height Hs is not provided (FIGS. 11 and 12). It is possible to suppress the decrease of the abruptly and abruptly decrease at the end. As the opening end height Hs increases, the flow rate on the end side can be increased and the film thickness on the end side can be increased.

  Therefore, in the embodiment, the spread width Wc, the inclination angle θc, the inclination height Hc, and the opening end height Hs are set in consideration of the above merits and demerits. Each dimension may be set as appropriate so as to obtain a quantity or the like.

  In the embodiment described above, the manifold 11 corresponds to the “first portion”, the opening end portion 12b corresponds to the “second portion”, and the opening inclined portion 12a corresponds to the “third portion”.

B. Variations:
The present invention is not limited to the above-described embodiments and modifications, and can be carried out in various modes without departing from the gist thereof. For example, the following modifications are possible.

  In the above-described embodiment, the case where the third portion is the opening inclined portion 12a in which the side wall of the flow path is configured by a plane having a constant inclination angle θc has been described as an example, but the third portion is not limited thereto. For example, the side wall of the flow path may be configured with a smooth curved surface. That is, it is only necessary that the width of the flow path is continuously increased from the upstream end toward the downstream end.

  In the above embodiment, a die head having a structure in which a shim is sandwiched between a pair of dies has been described as an example. However, the present invention is not limited to this, and the structure of the opening of the embodiment is applied to the slot of the slot die head. It may be.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above-described effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Die head 11 ... Manifold 12 ... Opening part 12Ra ... Opening part 12Rb ... Opening part 12a ... Opening inclined part 12b ... Opening end part 13 ... Opening end 20 ... Cooling roll 110 ... 1st die | dye 112 ... Opposite surface 115 ... Supply port 116 ... Supply hole 120 ... Second die 122 ... Opposing surface 124 ... Groove part 130 ... Shim 131 ... Upper area 132 ... Lower area 133 ... Opening inclined area 134 ... Opening end area 138 ... Side wall Ae ... Part AR ... Part Hc ... Inclination height Hs ... Opening end height MR ... Molten resin Pc ... Corner Wc ... Spreading width Wm ... Width Wo ... Width WS ... Resin film θc ... Inclination angle

Claims (1)

A die head for extrusion film formation in which a molten resin is supplied and molded into a film shape,
A first portion provided at the upstream end of the die head and having a flow path for circulating the molten resin;
A second part that is provided at a downstream end of the die head and distributes the molten resin through a flow path wider than the flow path of the first part;
Provided between the first part and the second part, and having a flow path connecting the flow path of the first part and the flow path of the second part, the molten resin from the first part A third part to be distributed to the second part;
With
The widths of the flow paths of the first part and the second part are constant,
The extrusion film-forming die head, wherein the flow path of the third portion continuously increases in width from the upstream end toward the downstream end.

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