JPH09150455A - Lateral stretching method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively obtain a stretched film high in thickness accuracy and having high function and high value added. SOLUTION: Hot air heated to predetermined temp. by a radiator 1 is injected to the upper and rear surfaces of a stretched film 7 and the injected hot air is returned to the rediator 1 by upper and lower return passages to be again heated to the predetermined temp. to be injected to the stretched film 7. When stretching is performed while this operation is repeated, in the respective upper and lower return passages, the hot air injected at a place relatively near to the radiator 1 and the hot air injected at a relatively remote place are mixed by first and second buffle plates 30, 30..., 40, 40.... The mixed hot air in the upper hot air return passage is guided to the lower part 1b of the radiator 1 by mixing ducts 10, 10 and the hot air mixed in the same way in the lower hot air return passage is guided to the upper part 1u of the radiator 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention injects hot air heated to a predetermined temperature by a radiator to the upper side and the lower side of a stretched film, heats the hot air blown again to a predetermined temperature with a radiator and jets it to the stretched film. The present invention relates to a lateral stretching method for stretching while repeating the above operation and a lateral stretching apparatus used for carrying out this method.

[0002]

2. Description of the Related Art When a stretched film formed of an oriented resin is stretched in an atmosphere at a temperature between the softening point and the melting point, a stretched film having a high tensile strength in the stretching direction can be obtained. A device for obtaining a large stretched film is conventionally known as a transverse stretching device and is constructed as shown in the schematic diagram of FIG. That is, a pair of upper and lower radiators 50, 50 'for heating hot air to a predetermined temperature between the softening point and the melting point of the stretched film, and a plurality of hot air heated by these radiators 50, 50' are arranged in parallel. The upper and lower nozzle chambers 52, 52 ', ...
Plenum boxes 51, 51 'for feeding to the two, two chains running while being spread in the hot air stove guided by a pair of rails, attached to these chains at predetermined intervals, and gripping both ears of the stretched film 60. A plurality of tenter clips 53, 53, ...
And so on.

Therefore, the upper and lower inverter motors 5
When the fans 54, 54 'are driven by 3, 53', the hot air heated to a predetermined temperature by the radiators 50, 50 'flows from the plenum boxes 51, 51' to the perforated plates 55, 5 '.
5 is equally supplied to the upper and lower nozzle chambers 52, 52 ', .... Then, from the upper nozzle chambers 52, 52, ... As shown by solid arrows, the stretched film 60 is drawn.
Is supplied to the upper side. The lower nozzle chambers 52 ', 5
From 2 '..., as indicated by the thick white arrows,
It is supplied to the lower side of the stretched film 60. In such a heated state, the tenter clips 5 are attached to both ears of the stretched film 60.
When it is gripped by 3, 53, ... And moved in the furnace, it is stretched as described above.

By the way, since the stretched film 60 is structurally divided into upper and lower parts in the hot air oven, the hot air injected from the upper nozzle chambers 52, 52, ... Is sucked by the upper fan 54. , And is heated again by the upper radiator 50 and supplied to the upper side of the stretched film 60 from the upper nozzle chambers 52, 52, ... As described above. Similarly, the hot air supplied to the lower side of the stretched film 60 is sucked by the lower fan 54 ', heated by the lower radiator 50', and then supplied from the plenum box 51 'to the nozzle chamber 52'. .

[0005]

As described above, in the hot air oven of the conventional transverse stretching apparatus, the hot air on the upper side circulates on the upper side and the hot air on the lower side circulates on the lower side with the stretching film 60 as a boundary. Therefore, the temperature of the hot air on the upper side of the stretched film 60 and the temperature of the hot air on the lower side may vary. Since this variation in temperature is generally small, it has little effect in stretch molding of ordinary resin, but when molding a stretched film of high function with high thickness accuracy and high added value,
Some variation in temperature is also a problem. It is considered that this variation in temperature can be solved to some extent by strictly controlling the temperatures of the radiators 50 and 50 ′, the amount of hot air, etc. However, such strict control causes a high cost and poses a practical problem. It is the actual situation that the horizontal stretching apparatus of (1) has a difficulty in dealing with this variation in temperature. Also, radiator 5
The hot air blown from a location relatively close to 0, 50 'returns to the radiators 50, 50' in a short circuit as shown by arrows a, a'in FIG. 8, and the hot air blown from a far location is short. , As shown by the arrows b and b ′, it makes a detour and returns to the radiators 50 and 50 ′. However, since there is a difference in the circulation path length, there is variation in temperature even in the circulation path. Has occurred. As a result, it is an obstacle to obtaining a high quality stretched film. Therefore, an object of the present invention is to provide a lateral stretching method capable of obtaining a highly functional, high-value-added stretched film with high thickness accuracy by an inexpensive method, and a transverse stretching apparatus used for carrying out this method. .

[0006]

In order to achieve the above object, the present invention jets hot air heated to a predetermined temperature by a radiator to the upper side and the lower side of a stretched film, and the jetted hot air is directed to the radiator. Reheated to a predetermined temperature and jetted to the stretched film, when stretching while repeating the above operation, the hot air jetted to the upper side of the stretched film is guided to the lower part of the radiator, and the hot air jetted to the lower side of the stretched film is It is arranged to lead to the upper part of the radiator. According to a second aspect of the present invention, hot air heated to a predetermined temperature by a radiator is jetted to the upper side and the lower side of the stretched film, and the jetted hot air is returned to the radiator by the upper and lower hot air return passages and is again set to the predetermined temperature. When heated to, and jetted to a stretched film, while stretching while repeating the above operation, in each of the upper and lower hot air return paths, hot air jetted relatively near the radiator and hot air jetted relatively far away are provided. While being mixed, the mixed hot air in the upper hot air return path is guided to the lower part of the radiator, and the mixed hot air in the lower hot air return path is guided to the upper part of the radiator. And Claim 3
According to the invention described in claim 1 or 2, the predetermined amount of hot air jetted to the upper side of the stretched film is guided to the lower part of the radiator, and the predetermined amount of hot air jetted to the lower side is guided to the upper part of the radiator. Composed. The invention according to claim 4 is provided with a radiator and a nozzle box arranged at a predetermined interval in a vertical direction so as to constitute a hot air oven in which a stretched film runs, and hot air heated by the radiator. Is jetted from the upper and lower nozzle boxes,
A horizontal stretching device in which jetted hot air is returned to a radiator through a hot air return passage to be heated, and is injected from the upper nozzle box into each of the upper and lower hot air return passages. A mixing duct is provided that guides hot air to a lower portion of the radiator and guides hot air injected from the lower nozzle box to an upper portion of the radiator. The invention according to claim 5 is a radiator,
It comprises a nozzle box arranged at a predetermined interval in the vertical direction so that a hot-air stove in which a stretched film runs is configured, and hot air heated by the radiator is jetted from the upper and lower nozzle boxes, and jetted. In the transverse stretching device, the generated hot air is heated by the radiator again through the upper and lower hot air return passages, and the hot air return passages at the upper and lower sides are relatively close to the radiator. First and second baffle plates that mix the hot air that has been jetted and the hot air that has been jetted relatively far are provided, and the hot air that has been jetted is jetted from the upper nozzle box on the downstream side. A mixing duct is provided for guiding the hot air to the lower part of the radiator and guiding the hot air injected from the lower nozzle box to the upper part of the radiator.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION First, a first embodiment of the present invention will be described with reference to FIGS. The transverse stretching apparatus according to the present embodiment is also generally configured in the same manner as the conventional transverse stretching apparatus described above, but according to the present embodiment, the hot air return passage near the radiator 1 is schematically illustrated in FIG. A mixing duct 10 is provided as shown in FIG. Thereby, as described later, the hot air jetted from the upper nozzle is guided to the lower radiator 1, and the hot air jetted from the lower nozzle is guided to the upper radiator 1,
The hot air will be mixed. A mixing duct 10 'is also provided on the right side of the radiator 1 in the figure, but it is not shown in the figure.

The transverse stretching apparatus of the first embodiment also has a radiator 1 as is well known. This radiator 1
Although it can be divided into upper and lower parts by a partition member or the like, it is shown in FIG. 1 as a radiator 1 consisting of only an upper part 1u and a lower part 1b. A plenum box 2 is provided on the downstream side of the radiator 1, that is, on the left side in the drawing. And in this plenum box 2,
A plurality of upper nozzle boxes 3, 3, ... And a plurality of lower nozzle boxes 4, 4, ... Are connected at a predetermined interval in the vertical direction. Each of these nozzle boxes 3, 3, ... 4, 4, ... Is provided with a plurality of hot air jet nozzles as is well known in the art. As a result, hot air stoves are formed between the upper and lower nozzle boxes 3, 3 ,. Although not shown in the figure, a perforated plate is provided at the outlet of the plenum box 2, and the upper and lower nozzle boxes 3, 3, ..., 4, 4, ... Are connected via this perforated plate. There is. Therefore, the hot air in the plenum box 2 is supplied to the nozzle boxes 3, 3, ...

In the hot-air stove between the upper nozzle boxes 3, 3, ... And the lower nozzle boxes 4, 4 ,. Chains are provided, and a plurality of tenter clips 8, 8, ... Which grip the two ears of the stretched film 7 and run in the hot air stove are attached to these chains.

The mixing duct 10 is schematically shown in FIG.
As shown in detail in FIG. 2, the first duct 11 is located above and the second duct 111 'is located below. And the first of these,
The two ducts 11 and 11 ′ are installed in the hot air return passage on the side of the radiator 1 or the plenum box 2.
The first duct 11 includes a pair of triangular side plates 12,
12 and a swash plate 13 that closes the hypotenuses of these side plates 12, 12 and is formed in a substantially prismatic shape so as to have a rectangular inlet opening 14 and a similarly rectangular outlet opening 15. ing. And the first duct 11
Are supported by the frames 20, 20, so that the inlet opening 14 thereof is horizontal and is located below the stretching film 7, and the outlet opening 15 is vertical and faces the upper portion 1u of the radiator 1.

A first hot air partition plate 21 is attached to the right side of the outlet opening 15 of the first duct 11. By this first hot air partition plate 21, substantially the entire amount of the hot air at the upper side is guided to the lower portion 1b of the radiator 1 as described later. When the first hot air partition plate 21 is not provided, about half the amount of hot air is guided to the lower portion 1b of the radiator 1. Therefore, the amount of hot air to be mixed can be adjusted by the first hot air partition plate 21. First hot air partition plate 21
In the present embodiment, is made of a plate material bent in an angle and is attached to the channel steel of the frame 20.

The second duct 11 'also has the same shape as the first duct 11. That is, a pair of side plates 12 'and 12' having a triangular shape opposite to the side plates 12 and 12 of the first duct 11 and a swash plate 13 'which closes the hypotenuses of these side plates 12' and 12 ' It has a substantially prismatic shape so as to have an entrance opening 14 'having a rectangular shape and an exit opening 15' having a rectangular shape. The second duct 11 ′ has frames 20, 20, so that its inlet opening 14 ′ is horizontal and is located above the stretching film 7, and the outlet opening 15 ′ is vertical and faces the lower portion 1 b of the radiator 1. It is supported by. Second duct 1
A second hot air partition plate 22 is also attached to the left side of the outlet opening 15 'of 1'. This second hot air partition plate 22
As a result, almost all of the hot air in the lower part is in the upper part 1
will be guided by u. The second hot-air partition plate 22 has the shape of channel steel in the present embodiment, and its flange portion is attached to the frames 20, 20, .... Note that reference numeral 23 in FIG. 2 indicates a side plate that constitutes a side wall of the hot air return passage. As described above, according to the present embodiment, the first,
Since the two ducts 11, 11 'are attached to the frames 20, 20, ..., the frames 20, 20, ... can be easily installed in the hot air return path of the conventional transverse stretching apparatus.

Next, the operation will be described. A fan (not shown) is driven to rotate. Then, the hot air heated to the predetermined temperature by the radiator 1 is equally divided by the perforated plate from the plenum box 2 into the upper and lower nozzle boxes 3,
3, ..., 4, 4, ... The upper nozzle boxes 3, 3, ... Are supplied to the upper side of the stretched film 7 as indicated by the hatched arrows. Further, the lower nozzle boxes 4, 4, ... Are supplied to the lower side of the stretched film 7 as indicated by thick arrows. In the hot-air oven in which hot air is blown in this way, the stretching film 7
The two ears are gripped by the tenter clips 8, 8, ... And stretched by running as is well known.

The hot air sprayed on the lower surface of the stretched film 7 is provided with the second hot air partition plate 22, so that
Is guided upward from the inlet opening 14 of the duct 11 and is guided from the outlet opening 15 to the upper portion 1u of the radiator 1.
Then, this time, it is heated by the upper portion 1u of the radiator 1. On the other hand, the hot air sprayed on the upper surface of the stretched film 7 is guided downward from the inlet opening 14 'of the second duct 11' and the outlet opening 15 because the first hot air partition plate 21 is provided. 'To the lower part 1b of the radiator 1. And this time, the lower part 1b of the radiator 1
Heated. As described above, according to the present embodiment,
The hot air sprayed above and below the stretched film 7 is alternately heated in the lower and upper portions 1b and 1u of the radiator 1, so that the temperature inside the hot air stove becomes uniform.

Next, a second embodiment of the present invention will be described with reference to FIG. The same members as those in the first embodiment shown in FIGS. 1 and 2 are designated by the same reference numerals and will not be described repeatedly. According to the present embodiment, the first baffle plates 30, 30, between the upper nozzle boxes 3, 3 ,.
, And second baffle plates 40, 40 ,. The first baffle plates 30, 30, ...
Is formed from a plate member having a substantially rectangular shape, and is provided farther from the radiator 1, and the second baffle plates 40, 40, ... Also having a rectangular shape are provided closer to the radiator 1.

The first baffle plates 30, 30, ...
, The left end portions 32, 32, ... Are located near the stretched film 7, and the right end portions 33, 33, ... Are located near the upper wall of the upper nozzle box 3, 3 ,. It is installed diagonally to the uphill. On the other hand, the second baffle plates 40, 40,
The left end portions 43, 43, ... Of the nozzle box 3 on the upper side,
The right end portions 42, 42, ... Are located near the upper wall 3, and are located near the stretched film 7, and are obliquely provided as a whole on a downward slope. Then, the right end portions 33, 33, ... Of the first baffle plates 30, 30, ... And the left end portions 42, 42, ... Of the second baffle plates 40, 40 ,.
There is a predetermined space between the mixing chamber C and
C, ... In addition, the lower nozzle box 4,
Baffle plates of the same shape as the above-mentioned first and second baffle plates 30, ..., 40, ... Are provided in the same positional relationship between the four, ..., Not shown in FIG.

It is possible to stretch in the same manner also in the second embodiment. That is, in the hot air blown from the upper nozzle boxes 3, 3, ..., a part of the hot air blown to a portion far from the radiator 1 is guided to the first baffle plates 30, 30 ,. Flow toward the mixing chambers C, C, ... As indicated by A, A, .... On the other hand, a part of the hot air injected to the portion close to the radiator 1 is guided by the second baffle plates 40, 40, ... And flows backward as shown by arrows B, B ,. And flows toward the mixing chambers C, C, .... In these mixing chambers C, C, ...
B), (AB), ..., Directed towards the mixing ducts 10, 10 '. The subsequent stretching is performed in the same manner as in the first embodiment.

According to the second embodiment, the first baffle plate 30, between the upper nozzle boxes 3, 3 ,.
, And the second baffle plates 40, 40, ... Are provided, so that hot air that is jetted from a portion relatively close to the radiator 1 and tends to be short-circuited, and hot air that is jetted from a far portion and makes a detour. And are mixed and guided towards the mixing ducts 10, 10 '. Therefore,
Variations in temperature are eliminated even during hot air circulation.

[0019]

【Example】

Example 1: FIG. 4 is a side view schematically showing the transverse stretching apparatus according to the first and second embodiments. In order to test the temperature distribution of the transverse stretching apparatus according to the first embodiment, , Temperature points were attached to the points as shown in FIG. 4, that is, the left end portion, the center portion and the right end portion of the upper and lower nozzle boxes 3, 4, ..., respectively, and the temperature was measured after operating for 30 minutes. . The results are shown in Table 1. The results are shown in a graph in FIG.

As is clear from Table 1, according to the first embodiment, the maximum value is 131.1 ° C and the minimum value is 129.
At 3 ° C, temperature variation is plus / minus 0.9 °
It was C. For comparison, the first and second ducts 11, 1
1'is removed and tested in the same position. The results are shown in Table 2 and FIG. As shown in Table 2 above, the first and second ducts 1
When there is no 1 or 11 ', the maximum value is 131.7 ° C, the minimum value is 127.7 ° C, and the temperature variation is plus or minus 2.0 ° C. As is clear from the above test results, the first with the mixing ducts 10 and 10 '
According to the embodiment, it can be seen that the temperature inside the hot-air stove is equalized.

Example 2: A temperature sensor was similarly attached to each of the left end portion, the central portion and the right end portion of the upper and lower nozzle boxes 3, 4, ... Of the lateral stretching apparatus according to the second embodiment, and 30 minutes The temperature was measured after running. Table 3 shows the results. Further, it is shown in a graph in FIG.

As is apparent from Table 3 above, according to the second embodiment, the variation in the vertical direction is plus / minus 0.6 ° C, and the variation in the horizontal direction is plus / minus 0.4 °. It is C. On the other hand, the first and second ducts 11 and 11 'and the first and second baffle plates 30 and
As shown in Table 2, the results of the test after removing 30, 40, 40, ... are +/- 2 ° C in the vertical direction and +/- 0 in the horizontal direction. Since it is 0.8 ° C, the remarkable effectiveness of the mixing ducts 10 and 10 'and the first and second baffle plates 30, 30, 40, 40, ... is recognized in the temperature equalization in the hot air stove. In addition, as shown in Table 1,
The first and second baffle plates 30, 30, 40, 40,
When there is no ..., the variation in the left-right direction is plus or minus 0.6 ° C, so the mixing ducts 10 and 1
0'first and second baffle plates 30, 30, 40,
It is understood that the effect of soaking is further enhanced by adding 40, .... From this, it can be seen that even if only the first and second baffle plates 30, 30, 40, 40, ... Are attached, a certain degree of temperature equalization is achieved as compared with the conventional one.

[0023]

As described above, according to the present invention, the hot air heated to a predetermined temperature by the radiator is jetted to the upper side and the lower side of the stretching film, and the jetted hot air is heated again by the radiator to stretch the film. When drawing while repeating the above operation, the hot air injected to the upper side of the drawing film is heated in the lower part of the radiator, and the hot air injected to the lower side of the drawing film is heated in the upper part of the radiator and drawn. Therefore, variations in temperature above and below the stretched film are reduced. Therefore, according to the present invention, it is possible to obtain a stretched film having high thickness accuracy, high function, and high added value. Moreover, according to the present invention, the hot air blown to the upper side of the stretched film is heated only in the lower part of the radiator and the hot air blown to the lower side is heated in the upper part, that is, the hot air return path is provided with the mixing duct. The temperature difference between the upper and lower sides of the stretched film is small even if the radiator accuracy is poor and there is a partial temperature difference, so it is highly functional with high thickness and high added value. The stretched film can be obtained at low cost. In addition, according to another invention, hot air heated to a predetermined temperature by a radiator is jetted to the upper side and the lower side of the stretched film,
The jetted hot air is returned to the radiator by the upper and lower hot air return paths and heated again to a predetermined temperature to be jetted to the stretching film.When stretching is repeated while repeating the above operation, even in each of the upper and lower hot air return paths, Since the hot air injected relatively close and the hot air injected relatively far are mixed, the variation in the temperature in the hot stove can be further suppressed. Therefore, it is possible to obtain a highly functional and high-value-added stretched film having higher thickness accuracy. At this time, the cost is not increased because only the first and second baffle plates are provided.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view schematically showing a transverse stretching apparatus according to a first embodiment of the present invention.

FIG. 2 is an enlarged perspective view of a main part shown in FIG.

FIG. 3 is a partially cutaway perspective view schematically showing a transverse stretching apparatus according to a second embodiment of the present invention.

FIG. 4 is a side view schematically showing a transverse stretching device and a temperature measurement point according to the embodiment of the present invention.

FIG. 5 is a graph showing a temperature measurement result of the transverse stretching device according to the first embodiment of the present invention.

FIG. 6 is a graph showing a temperature measurement result of a transverse stretching device according to a second embodiment of the present invention.

FIG. 7 is a graph showing a temperature measurement result of a conventional transverse stretching device.

FIG. 8 is a side view schematically showing a conventional transverse stretching device and a flow of hot air.

[Explanation of symbols]

1 radiator 1u upper part (radiator) 1b lower part (radiator) 3 upper nozzle box 4 lower nozzle box 7 stretched film 10, 10 'mixing duct 11 first duct (lower duct for guiding hot air to upper side) 11 '2nd duct (gu duct which guide | induces the hot air of an upper side to the lower side) 30,30 ... 1st baffle plate 40, 40 ... 2nd baffle plate

Claims (5)

[Claims] 1. Hot air heated to a predetermined temperature by a radiator (1) is jetted to the upper side and the lower side of a stretched film (7), and the jetted hot air is heated to a predetermined temperature again by the radiator (1). When the film is stretched while repeating the above-mentioned operation, which is sprayed on the stretched film (7), the hot air sprayed on the upper side of the stretched film (7) is guided to the lower part (1b) of the radiator (1) and stretched film (7). The horizontal stretching method, characterized in that the hot air jetted to the lower side of the radiator is guided to the upper portion (1u) of the radiator (1). 2. Hot air heated to a predetermined temperature by a radiator (1) is jetted to the upper side and the lower side of a stretched film (7), and the jetted hot air is returned to the radiator (1) through upper and lower hot air return paths. When the film is stretched while repeating the above-mentioned operation, it is heated to a predetermined temperature again and is jetted to the stretched film (7). In each of the upper and lower hot air return paths, the jet is performed relatively close to the radiator (1). The hot air and the hot air jetted relatively far away are mixed, and the mixed hot air in the upper hot air return path is mixed with the lower part (1) of the radiator (1).
b), and the similarly mixed hot air in the lower hot air return path is led to the upper part (1u) of the radiator (1). 3. A predetermined amount of hot air injected to the lower side (1b) of the radiator (1) by guiding a predetermined amount of hot air injected to the upper side of the stretched film (7) according to claim 1 or 2. A horizontal stretching method for guiding the resin to the upper portion (1u) of the radiator (1). 4. Nozzle boxes (3, 3, ..., 4) arranged at predetermined intervals in the vertical direction so that a radiator (1) and a hot air stove in which a stretched film (7) runs are constructed. , ..., and hot air heated by the radiator (1) is jetted from the upper and lower nozzle boxes (3, 3, ..., 4, 4, ...) And the hot air jetted is returned to the hot air return path. A horizontal stretching device adapted to be heated by being returned to a radiator (1) through a nozzle, and jetted from the upper nozzle box (3, 3, ...) Into the upper and lower hot air return paths, respectively. The generated hot air is guided to the lower part (1b) of the radiator (1), and the hot air injected from the lower nozzle box (4, 4, ...) Is guided to the upper part (1u) of the radiator (1). Mixing ducts (10, 10 ') are provided Transverse stretching device, characterized in that. 5. Nozzle boxes (3, 3, ..., 4) arranged at predetermined intervals in the vertical direction so that a radiator (1) and a hot air stove in which a stretched film (7) travels are constructed. , ..., and hot air heated by the radiator (1) is jetted from the upper and lower nozzle boxes (3, 3, ..., 4, 4, ...), and the jetted hot air is directed upward and downward. A lateral stretching device adapted to be heated again by a radiator (1) through a side hot air return passage, wherein the upper and lower hot air return passages are jetted relatively close to the radiator (1). First and second baffle plates (30, 30, ..., 40, 40, ...) for mixing the mixed hot air with the hot air sprayed at a relatively long distance are provided, and the downstream of the mixed hot air is provided. On the side, the upper nozzle box (3, 3, ...) The hot air injected from the radiator (1) is guided to the lower part (1b) of the radiator (1), and the hot air injected from the lower nozzle box (4, 4, ...) Is applied to the upper part (1u) of the radiator (1). 1. A transverse stretching device, characterized in that a mixing duct (10, 10 ') for guiding to is provided.