JP2016016526A - Film drawing apparatus, and film drawing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transfer thermal energy of air efficiently and uniformly to the surface of a film to improve quality of the film to be produced.SOLUTION: A film drawing apparatus includes a duct 7 equipped with a plurality of injection holes 12 through which air is injected to a film conveyed in one direction and an injection surface 11 which is opposed to a film surface and on which a plurality of the injection holes are arranged. A plurality of the injection holes 12 are arranged at the same interval in a close-packed hexagonal lattice manner. All of arrangement lines 13 virtually connecting adjacent spray holes 12 are inclined with respect to an MD direction and a TD direction orthogonal to the MD direction.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an air injection device for blowing air onto a film, and a heat treatment method for heating and cooling by blowing air at a predetermined temperature onto the film.

Biaxially stretched films represented by biaxially stretched polypropylene films and biaxially stretched polyester films are known. In the production process of a biaxially stretched film, generally, a solid raw material is melt-plasticized by an extruder, a molten resin material is discharged from a T-die into a thin and wide sheet shape, and the resin material is cooled and solidified by a forming roll. After being cooled and solidified, the resin material is stretched using a longitudinal stretching apparatus and a lateral stretching apparatus, respectively.
The transverse stretching apparatus used in such a film manufacturing process is a film width direction (hereinafter referred to as TD (Transverse Direction) direction) perpendicular to the film transport direction (hereinafter referred to as MD (Machine Direction) direction). The film passes through the inside of a heat treatment apparatus (hereinafter referred to as a tenter oven) while holding both ends with clips. In the tenter oven, stretching in the TD direction is performed by expanding the distance between the opposing clips in the TD direction while blowing the hot air blown from the nozzle injection holes provided in the duct and heating the film.

The heat treatment apparatus has, for example, a plurality of temperature control zones that are partitioned for each region in which preheating, heating, heat retention, and cooling are performed, and a plurality of ducts for injecting air are MD in each temperature control zone. Arranged along the direction.
The duct is disposed so as to face up and down across the film, and a plurality of nozzle rows are provided on the surface facing the surface of the film. The injection hole of each nozzle is provided on an injection surface parallel to the surface of the film, and a configuration in which air is blown onto the film from a direction perpendicular to the film surface is standard.
In particular, a preheating zone in which the film is preheated before being stretched while being heated is required to increase heat transfer efficiency with respect to the surface of the film as compared with other temperature control zones. In order to increase the heat transfer efficiency, it is effective to increase the amount and speed of hot air jetted from the nozzle holes and to set the hot air temperature high. However, from the viewpoint of reducing energy consumption, energy consumption can be greatly reduced by effectively increasing the heat transfer efficiency of the duct and optimizing the arrangement of the injection holes without setting the hot air temperature high. Is possible.

FIG. 12 shows an arrangement example of the nozzle injection holes. In FIG. 12, (a) shows a single nozzle injection hole, (b) shows a tetragonal lattice arrangement, and (c) shows a close-packed hexagonal lattice arrangement. In FIG. 12, the diameter of the injection hole is D, the radius of the region for obtaining the Nusselt number of the collision jet against the film is r, and the parameter for estimating the heat transfer coefficient of the collision jet is g.
Here, the shape and arrangement of the nozzle injection holes for injecting air from the duct will be described in comparison with the heat transfer coefficient of the impinging jet in the injection hole alone, as shown in FIG.
When the injection holes are circular, the arrangement of the plurality of injection holes is arranged in the form of a square lattice in the vertical and horizontal directions, and the arrangement is made in a close-packed hexagonal lattice so that the adjacent injection holes form a regular triangle. When the case is compared with the case of the single injection hole, the ratio of the heat transfer coefficient of the impinging jet is as follows: simple substance: square lattice arrangement: close-packed hexagonal lattice arrangement = 1: 3.1: 3.6 Become. Accordingly, it is known that the heat transfer efficiency is highest with respect to the film surface when the plurality of injection holes are arranged in a close-packed hexagonal lattice pattern (Non-Patent Documents 1 and 2).

In FIG. 13, the perspective view of the shape of the conventional common duct is shown. On the other hand, as shown in FIG. 13, the general duct 107 itself has a shape that is elongated in the TD direction and short in the MD direction. For this reason, on the ejection surface 111 of the duct 107, the hole rows of the nozzle holes 112 of the plurality of nozzles are arranged in 2 to 5 rows in the MD direction and in several tens rows in the TD direction. . Therefore, even when the injection holes are arranged in a square lattice pattern or a close-packed hexagonal lattice pattern, generally, each hole array arranged at intervals in the MD direction is defined as the TD direction. It extends in parallel. Therefore, in each hole row parallel to the TD direction, a plurality of injection holes are necessarily arranged on a straight line parallel to the MD direction, or the injection holes are arranged in a staggered manner along the TD direction. (See FIGS. 3 and 4). Thus, by arranging a plurality of injection holes in a line in parallel with the MD direction, when hot air is blown onto the film transported in the MD direction, the surface of the film has a sufficient amount of heat from the hot air in the TD direction. The area | region provided and the area | region where heat quantity is not fully provided from a hot air will generate | occur | produce. As a result, the thermal energy transmitted to the film is uneven at each position in the TD direction of the film being conveyed.
Patent Documents 1 and 2 propose an arrangement of injection holes for eliminating unevenness in the amount of heat that the film receives from hot air in the TD direction of the film. In this arrangement, in the plurality of hole rows arranged along the TD direction, the injection holes of each hole row are arranged so as to be shifted from each other with respect to the TD direction. They are arranged side by side at a uniform interval with respect to the direction. That is, the injection holes of each hole row are arranged in a cyclic order across each hole row from one end side to the other end side in the TD direction, and are arranged so that the phase differences in the TD direction are equal. ing. This arrangement makes it possible to make the thermal energy transmitted to the film uniform in the TD direction of the film being conveyed.

JP 2009-255511 A International Publication No. 2008/114586

Martin, H., "Heat and Mass Transfer Between Impinging Gas Jets and Solid Surfaces", Advances in Heat Transfer, Academic Press, New York, Vol. 13, pp.1-60 The Japan Society of Mechanical Engineers, Heat Transfer Handbook, First Edition, First Print, P.55

However, in the techniques described in Patent Documents 1 and 2 described above, the arrangement of the injection holes of the plurality of nozzles on the injection surface of the duct is not the above-described square lattice or close-packed hexagonal lattice arrangement. As described above, there is a problem that the heat transfer efficiency imparted to the surface of the film is lowered as compared with the close-packed hexagonal lattice arrangement having the highest heat transfer efficiency.
Therefore, in the TD direction of the film transported in the MD direction, it is necessary to make both heat energy transmitted to the film uniform and increase heat transfer efficiency imparted to the surface of the film.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an air jet apparatus and a heat treatment method that can efficiently transfer heat energy of air to the surface of a film without unevenness and can improve the quality of a film to be manufactured. And

In order to achieve the above-described object, an air injection device according to the present invention includes a plurality of injection holes for blowing air to a film conveyed in one direction, and an injection in which a plurality of injection holes are arranged facing the surface of the film. And an injection member having a surface. The plurality of injection holes are arranged at equal intervals in a close-packed hexagonal lattice, and all of the array lines that virtually connect the adjacent injection holes are perpendicular to the film transport direction and the film transport direction. Each is inclined with respect to the direction.
In the present invention, being arranged at regular intervals in the form of a close-packed hexagonal lattice means that it is arranged at each vertex and center (intersection of each array line) of a regular hexagon forming a close-packed hexagonal lattice projected on a plane. Pointing to be. In other words, this means that it is arranged at each vertex of an equilateral triangle arranged in combination with each other on a plane.

  According to the air injection device according to the present invention configured as described above, the heat transfer efficiency of the heat energy applied to the surface of the film is enhanced by arranging the injection holes in a close-packed hexagonal lattice shape. In addition, all of the array lines that virtually connect the adjacent injection holes to each other are inclined with respect to the transport direction and the width direction of the film, so that the injection holes adjacent in the width direction of the film are arranged. Since the interval is made uniform, the heat transfer efficiency in the width direction of the film is made uniform. Therefore, according to this invention, the heat transfer efficiency with respect to the conveyance direction and width direction of the surface of a film is each improved.

Moreover, the heat processing method which concerns on this invention has the heat processing process of spraying the air of predetermined temperature on the film conveyed by one direction from the several injection hole arranged in the injection surface facing the surface of a film. In the heat treatment step, all of the arrangement lines that are arranged at equal intervals in a close-packed hexagonal lattice and that virtually connect mutually adjacent injection holes are the film transport direction and the film width direction perpendicular to the transport direction. The air is blown onto the film from a plurality of injection holes arranged so as to be inclined with respect to each other.
In addition, the heat processing in this invention has pointed out including the heating of a film, heat retention, and cooling.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to transmit efficiently the thermal energy of the air sprayed on the surface of a film without unevenness, and the quality of the film manufactured can be improved.

It is sectional drawing which shows typically the tenter oven provided with the air injection apparatus of this embodiment. It is a perspective view which shows the principal part of the air injection apparatus of this embodiment. It is a top view which shows the example of arrangement | positioning with which 3 rows of hole rows are arranged with respect to MD direction regarding the arrangement of a close-packed hexagonal lattice. It is a top view which shows the example of arrangement | positioning with which the hole array of 5 rows is located in a line with respect to MD direction regarding arrangement | positioning of a close-packed hexagonal lattice shape. It is a top view which shows the close-packed hexagonal lattice-like arrangement | sequence in this embodiment. In FIG. 5, it is a top view which shows each hole row | line | column arranged at intervals with respect to MD direction. It is a top view which shows the arrangement | sequence of the injection hole in the duct of a 1st comparative example. It is a top view which shows the arrangement | sequence of the injection hole in the duct of a 2nd comparative example. It is a top view which shows the arrangement | sequence of the injection hole in the duct of an Example. It is a figure which shows the comparison result of the surface average heat transfer coefficient in MD direction of the film which passed the injection surface of one duct. It is a figure which shows the comparison result of the surface average heat transfer coefficient in the TD direction of the film which passed the injection surface of one duct. It is a figure which shows the example of arrangement | positioning of the injection hole of a nozzle. It is a perspective view which shows the shape of the conventional common duct.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a cross-sectional view of a tenter oven provided with the air injection device of the present embodiment, parallel to the TD direction. In FIG. 2, the perspective view of the principal part of the air injection apparatus of this embodiment is shown.
As shown in FIG. 1, a tenter oven that heat-treats a film in the film manufacturing process includes an air injection device 1 that blows air onto the surface of a film 3 that is conveyed in the MD direction, which is one direction, and a film that is conveyed. And a clip 6 for stretching the film 3 in the TD direction by gripping both sides in the TD direction.

The air injection device 1 according to the embodiment includes a plurality of pairs of ducts 7 serving as injection members for blowing air to both surfaces of a film 3 to be conveyed, a flow path 8 for supplying air of a predetermined temperature to each duct 7, And a fan 9 arranged in the path 8 for sending air to each duct 7. The pair of upper and lower ducts 7 are disposed at positions facing each other with the film 3 interposed therebetween, and are disposed at a predetermined interval in the MD direction of the film 3.
In the pair of ducts 7 arranged above and below the film 3, the positions of the plurality of injection holes 12 in the pair of ducts 7 are set so that the pressing force by the air blown onto the surface of the film 3 is equal on both surfaces of the film 3. Are the same.

  As shown in FIG. 2, the air injection device 1 includes a plurality of injection holes 12 for blowing air to the film 3 conveyed in the MD direction, and an injection in which the plurality of injection holes 12 are arranged facing the surface of the film 3. And a duct 7 having a surface 11. The plurality of injection holes 12 are arranged on the injection surface 11 in a close-packed hexagonal lattice at equal intervals, and all of the array lines 13 that virtually connect the centers of the adjacent injection holes 12 are film. The MD direction of 3 and the TD direction of the film 3 perpendicular to the MD direction are respectively inclined and arranged.

An operation of heating the film 3 in the air injection device 1 provided in the tenter oven configured as described above will be described.
The film 3 supplied to the air ejection device 1 is conveyed in the MD direction while being gripped by the clips 6 at both ends in the TD direction. The air injection device 1 injects hot air from the injection holes 12 of the pair of ducts 7 arranged above and below across the film 3 conveyed in the MD direction, and the hot air is blown onto the surface of the film 3 to thereby cause the film 3 to be blown. Heated.

The close-packed hexagonal lattice-like arrangement of the injection holes 12 in this embodiment described above will be described in detail.
First, when the nozzle injection holes 12 are arranged in a close-packed hexagonal lattice, as an example of the arrangement pattern of the injection holes 12, as shown in FIG. 3, three hole rows are arranged side by side in the MD direction. As shown in FIG. 4, a configuration in which five hole arrays are arranged side by side in the MD direction is conceivable.
As shown in FIGS. 3 and 4, in these configurations, when the film 3 is conveyed in the MD direction, hot air is continuously blown to the same position of the film 3 in the TD direction (same coordinates in the TD direction). The thermal energy is accumulated at the same position. For this reason, in the coordinate with respect to the TD direction of the film 3, the coordinate where heat energy is easy to be stored (easy to be applied) from hot air and the coordinate where heat energy is hard to be stored are distributed. As a result, in the TD direction of the film 3, there is an inconvenience that unevenness of heat energy transmitted to the film 3 is likely to occur.

Here, by rotating the close-packed hexagonal lattice-like arrangement pattern shown in FIG. 4 counterclockwise in FIG. 4, the arrangement line 13 connecting the adjacent injection holes 12 is formed on the injection surface 11. Tilt against the MD direction. As shown in FIG. 5, the smallest angle among the angles formed by the straight line L passing through one arbitrary injection hole 12 and parallel to the MD direction and the array line 13A passing through the one injection hole 12 is θ. To do. At this time, when the minimum angle θ (hereinafter referred to as the inclination angle θ of the closest-packed hexagonal lattice) forms a predetermined angle, as shown in FIG. 5, all the injection holes 12 are predetermined with respect to the TD direction. Are evenly arranged with an interval x. That is, the interval x corresponds to the pitch of the injection holes 12 with respect to the TD direction.
In other words, when the inclination angle θ of the close-packed hexagonal lattice is a predetermined angle, the plurality of injection holes 12 are arranged so as to periodically change positions in the MD direction, and each injection hole with respect to the TD direction Twelve phase differences are evenly arranged. Moreover, in the some injection hole 12 arrange | positioned in the injection surface 11 from the one end side in the TD direction to the other end side, the injection hole 12 located in the same coordinate in the TD direction does not exist.
At this time, all of the array lines 13 that connect the adjacent injection holes 12 are respectively inclined with respect to the MD direction and the TD direction of the film 3. That is, the injection holes 12 are arranged so that all the array lines 13 on the injection surface 11 are not parallel to the MD direction and the TD direction, respectively.

FIG. 6 shows each row of holes arranged at intervals in the MD direction in the same arrangement as the arrangement of the injection holes 12 shown in FIG. In FIG. 6, in one duct 7, the length of the array line 13 connecting adjacent injection holes 12 is W, and the length between two injection holes 12 arranged at both ends in the MD direction is WL.
In the arrangement example shown in FIG. 6, the injection hole 12i and the injection hole 12j are respectively arranged at the same coordinate in the TD direction. Such an arrangement needs to avoid the presence of the injection holes 12 at the same coordinates in the TD direction from the viewpoint of the problem in the present invention. For this reason, since the injection hole 12i and the injection hole 12j cannot substantially exist at the same time, only one of the injection hole 12i and the injection hole 12j exists. In this way, the first hole row (1) and the first 'hole row (1') shown in FIG. 6 can be regarded as the same hole row in the periodic arrangement pattern. For this reason, it can be considered that the arrangement example of the hole row shown in FIG. 6 is substantially a four-row arrangement including the first hole row (1) to the fourth hole row (4).

すなわち、本実施形態のエア噴射装置１は、複数の噴射孔１２が、式（１）を満たすように配列されている。
なお、本実施形態では、一例として最密六方格子を反時計回りに回転させて配置している。このため、最密六方格子の傾斜角θは、図６に示すように、噴射孔１２ｉと噴射孔１２ｊとを結ぶ直線に平行な方向、すなわちＭＤ方向に平行な直線（基準線）と、この直線の図６中左側に隣接する配列線１３とがなす角度として定義されている。しかし、最密六方格子を反時計回りに回転させて配置する構成に限定するものではなく、時計回りに回転させて配置してもよく、本実施形態と同一の効果を得ることができる。最密六方格子を時計回りに回転させて配置する場合、最密六方格子の傾斜角θは、ＭＤ方向に平行な直線と、この直線の右側に隣接する配列線１３とがなす角度として定義される。 Here, when the number of the plurality of hole rows in which the injection holes 12 are arranged in a row and are arranged at an interval in the MD direction is n, the inclination angle θ of the close-packed hexagonal lattice is defined by the equation (1). Is done.

That is, in the air injection device 1 of the present embodiment, the plurality of injection holes 12 are arranged so as to satisfy the formula (1).
In this embodiment, as an example, the close-packed hexagonal lattice is rotated counterclockwise. Therefore, the inclination angle θ of the close-packed hexagonal lattice is, as shown in FIG. 6, a direction parallel to the straight line connecting the injection holes 12i and 12j, that is, a straight line (reference line) parallel to the MD direction. It is defined as the angle formed by the adjacent array line 13 on the left side in FIG. However, the present invention is not limited to the configuration in which the close-packed hexagonal lattice is arranged by rotating counterclockwise, and may be arranged by rotating clockwise to obtain the same effect as that of the present embodiment. When a close-packed hexagonal lattice is rotated and arranged clockwise, the inclination angle θ of the close-packed hexagonal lattice is defined as an angle formed by a straight line parallel to the MD direction and an array line 13 adjacent to the right side of the straight line. The

  By using the formula (1), when a plurality of hole rows arranged on the injection surface 11 of the duct 7 with a gap in the MD direction are arranged in three rows, n = 3 and θ = 19. Once. Further, when the number of hole rows arranged at intervals in the MD direction is four, n = 4 and θ = 13.9 degrees. Further, when the number of hole rows arranged at intervals in the MD direction is five, n = 5 and θ = 10.9 degrees. That is, as the number n of hole rows arranged at intervals in the MD direction increases, the inclination angle θ gradually decreases.

すなわち、本実施形態のエア噴射装置１は、複数の噴射孔１２が、式（２）を満たすように配列されている。 Furthermore, using the number n of the hole rows, the inclination angle θ, and the length W of the array line 13, the interval x between the injection holes 12 in the TD direction is defined by Expression (2).

That is, in the air injection device 1 of the present embodiment, the plurality of injection holes 12 are arranged so as to satisfy the formula (2).

By using Equation (2), when the number n of hole rows is three, n = 3 and x = 0.327W. When the number n of the hole rows is three, n = 3 and x = 0.327W. In addition, when the number n of the hole rows is four, n = 4 and x = 0.240W. In addition, when the number n of the hole rows is five, n = 5 and x = 0.189W.
Therefore, when the length W of the array line 13 is constant, the interval x between the injection holes 12 in the TD direction becomes smaller as the number n of the hole rows arranged at intervals with respect to the MD direction increases. .

Here, regarding the arrangement example of the injection holes 12 shown in FIG. 6, using the formula (1) and the formula (2), for example, when the length of the array line is W = 40 mm, the MD direction is When the number n of the hole rows arranged at intervals is four, x = 9.6 mm. In this case, if the diameter of the injection hole 12 is formed to be φ9.6 mm or more, the hot air from the injection hole 12 is blown over the entire region facing the injection surface 11 in the TD direction of the surface of the film 3. . Therefore, the film 3 passing through the ejection surface 11 of one duct 7 is substantially given thermal energy from the hot air over the entire area in the TD direction, and the injection holes 12 are formed in a close-packed hexagonal lattice shape. By arranging in the above, the effect of increasing the heat transfer efficiency of the heat energy applied to the surface of the film 3 is also obtained. That is, the film 3 can be efficiently heated without unevenness.
In addition, when the space | interval x of the injection hole 12 in TD direction is too large rather than the diameter of the injection hole 12, distribution of the amount of heat provided with the hot air sprayed on the film 3 conveyed in MD direction is TD direction. It tends to occur. Therefore, in order to heat the film uniformly in the TD direction, it is desirable to set the diameter of the injection holes 12 to be equal to or larger than the interval x between the injection holes 12 as described above.

(Example)
About the effect of the air injection device 1 of embodiment mentioned above, the result compared with the comparative example is demonstrated.
FIG. 7 shows a plan view of the arrangement of the injection holes 12 in the duct 7 of the first comparative example. FIG. 8 shows a plan view of the arrangement of the injection holes 12 in the duct 7 of the second comparative example. In FIG. 9, the top view of the arrangement | sequence of the injection hole 12 in the duct 7 of an Example is shown.
In the first and second comparative examples and examples, the temperature of the air supplied from the fan 9 to the duct 7 is 160 ° C., the flow rate of the air supplied to the duct 7 is 93 [m ³ / min], and the duct 7 is The initial temperature of the passing film 3 (temperature before passing through the duct 7) was set to 20 ° C. The film 3 had a width dimension in the TD direction of 900 mm and a conveyance speed of 240 [m / min].
As for the external dimensions of the duct 7, the injection hole 12 is arranged over a region of 1100 mm in the TD direction so that the length in the TD direction is 1600 mm, the length in the MD direction is 300 mm, and air is blown over the entire width of the film 3. Moreover, the distance (distance H shown in FIG. 2) between the surface of the film 3 and the ejection surface 11 of the duct 7 was set to 140 mm.
As shown in FIG. 7, in the first comparative example, the first hole row (1) and the third hole row (3) have the injection holes 12 arranged in parallel with the TD direction at a pitch of 60 mm, and the arrangement is the same. I made it. In the second hole row (2), the injection holes 12 are arranged at a pitch of 60 mm in parallel with the TD direction, and the injection holes 12 are located at the center between the adjacent injection holes 12 in the first hole row (1). As described above, the positions are shifted from the TD direction.
As shown in FIG. 8, in the second comparative example, the first hole row (1), the second hole row (2), and the third hole row (3) have the injection holes 12 parallel to the TD direction at a pitch of 72 mm. Arranged by. Further, the positions of the injection holes 12 in the second hole row (2) are shifted from the positions of the injection holes 12 in the first hole row (1) by 1/3 pitch. Similarly, the positions of the injection holes 12 in the third hole row (3) are shifted by 1/3 pitch with respect to the positions of the injection holes 12 in the second hole row (2). Therefore, the injection holes 12 of the second hole row (2) and the injection holes 12 of the third hole row (3) are shifted from each other by 1/3 pitch with respect to the injection holes 12 of the first hole row (1). Are arranged.

As shown in FIG. 9, in the embodiment, the injection holes 12 are arranged in a close-packed hexagonal lattice, the length W of the array line 13 is 82 mm, and the number n of the hole rows of the injection holes 12 is 4. The injection holes 12 were arranged so as to satisfy 1). The inclination angle θ of the close-packed hexagonal lattice in the example was 13.9 degrees.
Moreover, in each arrangement of the first comparative example, the second comparative example, and the example, since the total number of the injection holes 12 arranged on the injection surface 11 is different, the flow rate of air from the injection holes 12 is set to a constant value. Therefore, the diameters of the injection holes 12 are set so that the flow rates are equal to each other. In the first comparative example, the second comparative example, and the example, the diameter of the injection hole 12 in the first comparative example is set to φ25 mm so that the flow rate from the injection hole 12 is 30 [m / s]. The diameter of the injection hole 12 in the comparative example 2 was set to φ22 mm, and the diameter of the injection hole 12 in the example was set to φ22 mm.

10 and 11 show the results of evaluating the surface average heat transfer coefficient with respect to the film 3 for the arrangement of the injection holes in the first comparative example, the second comparative example, and the examples configured as described above.
In FIG. 10, the comparison result of the surface average heat transfer coefficient [W / m < ² > K] in the MD direction of the film 3 which passed the injection surface 11 of the one duct 7 is shown. In FIG. 11, the comparison result of the surface average heat transfer coefficient [W / m < ² > K] in the TD direction of the film 3 which passed the injection surface 11 of the one duct 7 is shown.
In the arrangement of the first comparative example, since the pitch of the injection holes 12 in the TD direction is relatively narrow 60 mm, the air injected from the injection holes 12 adjacent to each other in the TD direction interferes with each other, and the film 3 The heat transfer efficiency to the surface of the steel was reduced. As a result, in the first comparative example, as shown in FIGS. 10 and 11, the surface average heat transfer coefficient in the MD direction and the TD direction was about 53.2 [W / m ² K].
In the arrangement of the second comparative example, since the pitch of the injection holes 12 in the TD direction is 74 mm wider than that of the first comparative example, the air injected from the injection holes 12 adjacent to each other in the TD direction interferes with each other. The heat transfer efficiency in the TD direction was higher than that in the first comparative example. As a result, as shown in FIG. 11, in the second comparative example, the surface average heat transfer coefficient in the TD direction is 61.4 [W / m ² K], which is 15.2% compared to the first comparative example. Improved. Further, in the arrangement of the second comparative example, the injection holes 12 of the first hole row (1) to the third hole row (3) are arranged by shifting the position by 1/3 pitch with respect to the TD direction. Thus, the heat transfer efficiency in the MD direction was increased. As a result, as shown in FIG. 10, in the second comparative example, the surface average heat transfer coefficient in the MD direction is 61.0 [W / m ² K], which is 14.7% compared with the first comparative example. Improved.

In the arrangement of the present embodiment, they are arranged in a close-packed hexagonal lattice pattern, and are arranged evenly at intervals x in the TD direction, that is, at a predetermined pitch in the TD direction. As shown, the surface average heat transfer coefficient in the MD direction is 67.0 [W / m ² K], which is 26% higher than that of the first comparative example, and 9.8 higher than that of the second comparative example. % Improved. In the arrangement of the example, as shown in FIG. 11, the surface average heat transfer coefficient in the TD direction is 67.1 [W / m ² K], which is 25.9% higher than that of the first comparative example. Compared to the second comparative example, it was improved by 9.3%.

As described above, according to the air injection device 1 of the embodiment, the injection holes 12 are arranged in a close-packed hexagonal lattice, and the injection holes 12 are arranged so as to satisfy the formula (1). In the entire surface 11, the intervals x between the injection holes 12 arranged side by side in the TD direction are evenly arranged (the phase difference of the injection holes 12 with respect to the TD direction is evenly arranged). Thereby, the surface average heat transfer coefficient with respect to the surface of the film 3 can be enhanced by the close-packed hexagonal lattice arrangement, and the thermal energy applied to the film 3 is made uniform in the TD direction of the film 3 being conveyed. be able to.
Therefore, the air injection device 1 according to the embodiment can efficiently transmit the thermal energy of air to the surface of the film 3 without unevenness, and can improve the quality of the film 3. As a result, according to the present embodiment, the arrangement of the injection holes 12 can be optimized, the film 3 can be efficiently heated, and the energy consumption can be reduced.
In addition, this invention is not limited to the heating of a film, Of course, it may be used for heat processing, such as cooling and heat retention.

DESCRIPTION OF SYMBOLS 1 Air injection apparatus 3 Film 7 Duct 11 Injection surface 12 Injection hole 13 Array line

The present invention relates to a film stretching apparatus including an air injection device for spraying air onto a film, and a film stretching method in which air at a predetermined temperature is sprayed on the film for heating and cooling.

Therefore, the present invention provides a film stretching apparatus and a film stretching method that can efficiently transfer the thermal energy of air to the surface of the film without unevenness and can improve the quality of the produced film. Objective.

In order to achieve the above-described object, a film stretching apparatus according to the present invention includes an air ejecting apparatus , and the air ejecting apparatus includes a plurality of ejection holes for blowing air to a film conveyed in one direction while stretching , An injection member having an injection surface facing the surface and in which a plurality of injection holes are arranged. The plurality of injection holes are arranged at equal intervals in a close-packed hexagonal lattice, and all of the array lines that virtually connect the adjacent injection holes are perpendicular to the film transport direction and the film transport direction. Each is inclined with respect to the direction.
In the present invention, being arranged at regular intervals in the form of a close-packed hexagonal lattice means that it is arranged at each vertex and center (intersection of each array line) of a regular hexagon forming a close-packed hexagonal lattice projected on a plane. Pointing to be. In other words, this means that it is arranged at each vertex of an equilateral triangle arranged in combination with each other on a plane.

According to the film stretching apparatus according to the present invention configured as described above, the heat transfer efficiency of the heat energy applied to the film surface is increased by arranging the injection holes of the air injection apparatus in a close-packed hexagonal lattice shape. It is done. In addition, all of the array lines that virtually connect the adjacent injection holes to each other are inclined with respect to the transport direction and the width direction of the film, so that the injection holes adjacent in the width direction of the film are arranged. Since the interval is made uniform, the heat transfer efficiency in the width direction of the film is made uniform. Therefore, according to this invention, the heat transfer efficiency with respect to the conveyance direction and width direction of the surface of a film is each improved.

Moreover, the film stretching method according to the present invention includes a heat treatment step of blowing air at a predetermined temperature from a plurality of spray holes arranged on a spray surface facing a film surface onto a film that is conveyed in one direction while stretching. Have. In the heat treatment step, all of the arrangement lines that are arranged at equal intervals in a close-packed hexagonal lattice and that virtually connect mutually adjacent injection holes are the film transport direction and the film width direction perpendicular to the transport direction. The air is blown onto the film from a plurality of injection holes arranged so as to be inclined with respect to each other.
In addition, the heat processing in this invention has pointed out including the heating of a film, heat retention, and cooling.

Claims (9)

An injection member having a plurality of injection holes for blowing air to the film conveyed in one direction, and an injection surface facing the surface of the film and in which the plurality of injection holes are arranged;
The plurality of injection holes are arranged at equal intervals in a close-packed hexagonal lattice pattern on the injection surface, and all of the array lines that virtually connect the injection holes adjacent to each other are transported by the film. An air injection device that is inclined with respect to the width direction of the film perpendicular to the direction and the transport direction. On the ejection surface, θ is the smallest angle among the angles formed by the straight line passing through the one ejection hole and parallel to the transport direction and the array line passing through the one ejection hole, and the ejection hole Are arranged in a row and the number of a plurality of hole rows arranged at intervals with respect to the transport direction is n,

The air injection device according to claim 1, wherein the plurality of injection holes are arranged so as to satisfy. On the ejection surface, θ is the smallest angle among the angles formed by the straight line passing through the one ejection hole and parallel to the transport direction and the array line passing through the one ejection hole, and the ejection hole Are arranged in a row and the number of a plurality of hole rows arranged at intervals in the transport direction is n, and the length of the array line is W, the interval between the injection holes adjacent in the width direction x is

The air injection device according to claim 1, wherein the plurality of injection holes are arranged so as to satisfy.   The diameter of the said injection hole is an air injection apparatus of Claim 3 which is more than the said space | interval x.   5. The air injection device according to claim 1, wherein the plurality of injection holes are arranged at positions facing each other with the film conveyed in the conveyance direction interposed therebetween. The film conveyed in one direction has a heat treatment step of blowing air at a predetermined temperature from a plurality of injection holes arranged on the injection surface facing the surface of the film,
In the heat treatment step, all of the array lines that are arranged at equal intervals in a close-packed hexagonal lattice and that virtually connect the spray holes adjacent to each other are orthogonal to the transport direction and the transport direction of the film. A heat treatment method, wherein air is blown onto the film from the plurality of injection holes arranged to be inclined with respect to the width direction of the film. In the heat treatment step, the minimum angle among the angles formed by the straight line passing through the one injection hole and parallel to the transport direction and the array line passing through the one injection hole on the injection surface is θ. And when the number of the plurality of hole rows arranged in a row and spaced apart with respect to the transport direction is n,

The heat treatment method according to claim 6, wherein air is blown onto the film from the plurality of injection holes arranged so as to satisfy the conditions. In the heat treatment step, the minimum angle among the angles formed by the straight line passing through the one injection hole and parallel to the transport direction and the array line passing through the one injection hole on the injection surface is θ. And when the number of the plurality of hole rows arranged in a row and spaced apart from each other in the transport direction is n and the length of the array line is W, they are adjacent in the width direction. The injection hole interval x is

The heat treatment method according to claim 6, wherein air is blown onto the film from the plurality of injection holes arranged so as to satisfy the conditions.   The heat treatment method according to claim 8, wherein a diameter of the injection hole is set to be not less than the interval x.

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