JP4874586B2 - Biaxially stretched nylon film manufacturing method and biaxially stretched nylon film manufacturing apparatus - Google Patents

Description

The present invention relates to a biaxially stretched nylon film manufacturing method and a biaxially stretched nylon film manufacturing apparatus.

Biaxially stretched films are often used after being subjected to multicolor printing as a surface base material for various packaging materials. On the other hand, when manufacturing a biaxially stretched film, it is common to heat-process (heat-set) to the base film after extending | stretching. By this heat treatment, the heat resistance and the like of the biaxially stretched film are drastically improved, and a practically excellent film is obtained.
As a heat treatment method, a tenter method is generally used. Specifically, heat treatment is performed by running in a heat treatment apparatus while fixing both ends of the stretched base film with clips or the like. At this time, the force that the central part of the base film returns to the original due to the contraction stress acts, and as a result, a so-called bowing phenomenon occurs. That is, since both ends of the base film are fixed with clips or the like, the central part of the base film is relatively slow in progress compared to the both ends, so that it is deformed like a bow (boeing) from the heat treatment apparatus. Will be discharged.

When such a bowing phenomenon occurs, even if there is no difference in the film appearance between the end portion and the center portion of the heat-treated base film (biaxially stretched film), a difference in physical properties will occur. For example, in the case of a biaxially stretched nylon film, the end of the film is particularly prone to tarnish, which causes troubles during printing and laminating.
Therefore, in a heat treatment apparatus, a method of setting the heating temperature in the vicinity of the ear part (end part) of the base film higher than the other parts (for example, Patent Document 1) or two-step heat treatment is performed on the base film. A method (for example, Patent Document 2) has been proposed.

Japanese Patent Laid-Open No. 3-126523 Japanese Patent Laid-Open No. 3-106635

  However, in the method of Patent Document 1, it is difficult to control the heating temperature, and in the method of Patent Document 2, there is a problem in terms of operation and equipment, such as the need to make the first stage heat treatment apparatus very large. It was.

Then, the objective of this invention is providing the manufacturing method of the biaxially stretched nylon film which can manufacture stably the biaxially stretched nylon film with few bowing phenomena, and a biaxially stretched nylon film manufacturing apparatus.

The method for producing a biaxially stretched nylon film of the present invention is a method for producing a biaxially stretched nylon film including a biaxially stretched step and a subsequent heat treatment step, and the raw material of the biaxially stretched nylon film is nylon. 6 and applying a tension T shown in the following formula (1) from the downstream side to the base film that has been subjected to the heat treatment in the heat treatment step while gripping the end portion.
118 ≦ T ≦ 196 (1)
(In the formula, T represents the tension per 1 m width and 15 μm thickness of the base film. The unit is N.)

According to the method for producing a biaxially stretched nylon film of the present invention, in the heat treatment step, a specific range of tension is applied from the downstream side to the base film undergoing the heat treatment. Therefore, the base film is stretched in the direction opposite to the direction of shrinkage during the heat treatment, and as a result, the bowing phenomenon that occurs in the base film can be reduced. Here, when the tension T is less than 98 N, tarmi tends to occur at both ends of the film after heat setting, the smoothness of the film is lost, and troubles occur during printing and laminating. On the other hand, when the tension T exceeds 196 N, the film is easily broken in the tenter of the heat treatment apparatus (deterioration of heat treatment moldability). The tension T is preferably 118N or more and 176N or less.

In this invention, it is preferable that the said tension | tensile_strength is controlled by the tension control apparatus provided in the downstream of the said heat processing process.
According to the present invention, since the tension on the base film is controlled by the tension control device provided on the downstream side of the heat treatment step, the tension is applied to the base film that is passing through the heat treatment step in terms of equipment. It becomes easy. Moreover, the biaxially stretched nylon film manufacturing apparatus itself can be simplified.

In the present invention, it is preferable that the tension control device includes a dancer roll.
According to the present invention, the tension control device includes the dancer roll, and tension can be applied to the base film by a simple operation of the dancer roll moving up and down. That is, the tension control device itself does not require a complicated configuration.

In the present invention, it is preferable that the heat treatment step includes a preliminary heat treatment step and a main heat treatment step performed thereafter.
According to the present invention, since the substrate film passes through the preliminary heat treatment step, the crystallinity of the substrate film is increased, and the heat treatment in the subsequent heat treatment step performed smoothly proceeds. Note that this heat treatment step is also simply referred to as a heat treatment step when it can be distinguished from the preliminary heat treatment step.

In the present invention, the biaxial stretching is preferably a tubular system.
If tubular method, it is possible to carry out simultaneous biaxial stretching in MD direction and TD direction (movement direction of the film) (the direction perpendicular to the moving direction of the film), biaxially oriented nylon films obtained are MD Excellent in strength balance between direction and TD.

The biaxially stretched nylon film manufacturing apparatus of the present invention is a biaxially stretched nylon film manufacturing apparatus including a biaxially stretched apparatus and a heat treatment apparatus, and the raw material of the biaxially stretched nylon film is nylon 6, and tension control An apparatus is provided on the downstream side of the heat treatment apparatus, and the tension control device is shown in the following formula (1) from the downstream side with respect to the base film that is subjected to the heat treatment while the end portion is held inside the heat treatment apparatus. It is characterized by applying a tension T.
118 ≦ T ≦ 196 (1)
(In the formula, T represents the tension per 1 m width and 15 μm thickness of the base film. The unit is N.)

  According to this invention, the tension | tensile_strength of a specific range is applied with respect to the base film which has received heat processing inside the heat processing apparatus from the tension control apparatus located downstream. Therefore, the base film is stretched in the direction opposite to the direction of shrinkage during the heat treatment, and as a result, the bowing phenomenon that occurs in the base film can be reduced.

In the present invention, it is preferable that the tension control device includes a dancer roll.
According to the present invention, the tension control device includes the dancer roll, and tension can be applied to the base film by a simple mechanism of the dancer roll moving up and down. Therefore, the biaxially stretched nylon film manufacturing apparatus itself can be simplified.

Below, the best form for implementing the manufacturing method of the biaxially stretched film which is this invention is explained in full detail based on drawing. Specifically, the apparatus which comprises each process of biaxially stretched film manufacture, and its operation | movement are demonstrated in detail.
[Outline of biaxially stretched film production equipment]
FIG. 1 is a schematic view showing a tubular biaxially stretched film manufacturing apparatus 100 as an example of the present invention.

  The biaxially stretched film manufacturing apparatus 100 includes a biaxial stretching apparatus (tubular stretching apparatus) 10 that stretches an unstretched original fabric film 1 (hereinafter also referred to as the original fabric film 1), and a base film 2 that is folded after stretching. (Hereinafter, also simply referred to as film 2) a preheating apparatus (preheating furnace) 20 for preheating, a separating apparatus 30 for separating the preheated film 2 into two upper and lower sheets, and a heat treatment (heat setting) for the separated film 2 A heat treatment device 40 for performing heat treatment, a tension control device 50 for applying tension to the film 2 from the downstream side when the film 2 is heat-fixed, and a biaxially stretched film 3 (hereinafter simply referred to as film 3). And a winding device 60 that winds up the material.

  The tubular stretching apparatus 10 is an apparatus for producing a film 2 by biaxially stretching a tubular raw film 1 produced by an extruder (not shown) by the pressure of internal air. And the guide plate 11 and the pinch roll 12 are provided as a means which folds this film 2 flatly and sends it to the downstream preheating furnace 20.

  The preheating furnace 20 is an apparatus for preliminarily heat-treating the flat film 2. The film 2 is heat-treated in advance at a temperature not lower than the shrinkage start temperature of the film 2 and about 30 ° C. lower than the melting point of the film 2 or lower. By this preliminary heat treatment, the degree of crystallinity of the film 2 increases, and the slipping property between the overlapping films becomes good.

The separation device 30 includes a guide roll 31, a trimming device 32, separation rolls 33A and 33B, and grooved rolls 34A to 34C.
The trimming device 32 has a blade 321 and cuts off both ends of the flat film 2 fed through the guide roll 31 to separate it into two films 2A and 2B. And these are isolate | separated by interposing air between both film 2A, 2B sent via the guide roll 31 by a pair of separation roll 33A, 33B located up and down. The incision of the flat film 2 may be performed so that a part of the ear is generated by positioning the blade 321 slightly inward from both ends, or by positioning the blade 321 in the fold portion of the film 2, You may carry out so that an ear | edge part may not arise.
Next, the two films 2A and 2B are overlapped again by the three grooved rolls 34A to 34C which are sequentially positioned in the traveling direction of the two films 2A and 2B. In addition, these rolls 34A-34C with a groove | channel carry out the plating process on the surface after a grooved process. A good contact state between the films 2A and 2B and the air can be obtained through the grooves.

The heat treatment apparatus 40 includes a tenter 41 that is a means for gripping both ends of the two films 2A and 2B, and a heating furnace 42 that is a heating means for heat-treating the two films 2A and 2B gripped at both ends. And. The heating furnace 42 is a hot air furnace, for example.
The overlapped films 2A and 2B are heat-treated at a temperature equal to or lower than the melting point of the resin constituting the film 2 and about 30 ° C. lower than the melting point while being gripped at both ends by clips (not shown) of the tenter 41. A biaxially stretched film 3 (hereinafter also referred to as film 3) having a stable physical property is obtained.
Further, a strong tension is applied to the films 2A and 2B in the heating furnace 42 by a tension control device 50 (described later) located on the downstream side.

  The winding device 60 includes a guide roll 61 and a winding roll 62. The heat-fixed film 3 is wound as two films 3 </ b> A and 3 </ b> B on two winding rolls 62 via a guide roll 61 via a tension control device 50.

[Outline of tension control device]
In FIG. 2, the schematic which looked at the tension control apparatus 50 from the side is shown.
The tension control device 50 includes two free rolls 51A and 51B and a dancer roll 52 that is positioned between them and can be displaced (moved) up and down.
The film 3 sent from the heat treatment apparatus 40 passes through the free roll 51A and the dancer roll 52, and is then sent from the free roll 51B to the winding apparatus 60.
The free rolls 51A and 51B only rotate freely in accordance with the progress of the film 3 from the heat treatment apparatus 40, but the dancer roll 52 can be displaced up and down. Therefore, when the dancer roll 52 is displaced downward, the tension of the film 3 increases, and conversely, when the dancer roll 52 is displaced upward, the tension of the film 3 decreases. That is, the tension of the film 2 that has been heat-treated in the heat treatment apparatus 40 located upstream can be controlled by the vertical displacement of the dancer roll 52.

Specifically, a tension T shown in the following formula (1) is applied to the film 2 that has been heat-treated inside the heat treatment apparatus 40 by the dancer roll 52 of the tension control apparatus 50 from the downstream side.
98 ≦ T ≦ 196 (1)
(In the formula, T represents the tension per 1 m width and 15 μm thickness of the film substrate. The unit is N.)
Here, when T is less than 98 N, the effect of preventing the bowing phenomenon is not sufficient, and tarmi tends to occur at both ends of the film 3 after heat setting. As a result, the smoothness of the film 3 is lost, and troubles are likely to occur during printing and laminating.
On the other hand, when T exceeds 196N, the film 2 is likely to break in the tenter 41 (near the clip) of the heat treatment apparatus 40 (deterioration of heat treatment moldability). The tension T is preferably 118N or more and 176N or less.

Moreover, it is preferable that the tension | tensile_strength T added from the downstream side with respect to the film 2 currently heat-processed inside the heat processing apparatus satisfy | fills the relationship shown in following formula (2).
0.025 ≦ T / K ≦ 0.06 (2)
(In the formula, K is the breaking strength in the MD direction of the film 3 and the unit is MPa. The breaking strength is measured in accordance with ASTM D882.)
Here, when T / K is less than 0.025, the effect of preventing the bowing phenomenon is not sufficient, and tarmi tends to occur at both ends of the film 3 after heat setting. As a result, the smoothness of the film 3 is lost, and troubles are likely to occur during printing and laminating. On the other hand, when T / K exceeds 0.06, breakage of the film 2 tends to occur in the tenter 41 (near the clip) of the heat treatment apparatus 40 (deterioration of heat treatment formability). T / K is preferably 0.027 or more and 0.053 or less.

As described above, according to the biaxially stretched film manufacturing apparatus 100 of the present invention, the tension controller 50 is installed on the downstream side with respect to the film 2 that has undergone the heat treatment inside the heat treatment apparatus 40, and the specific tension Since the control is performed, it becomes difficult for tarmi to occur at both ends of the film 3 after heat setting, and as a result, no trouble occurs during printing or laminating.
Further, the tension control device 50 controls the tension on the film 2 by a simple mechanism of the up and down movement of the dancer roll 52, and does not complicate the entire biaxially stretched film manufacturing apparatus. It is.

Although the best configuration for carrying out the present invention has been disclosed in the above description, the present invention is not limited to this. That is, although the present invention has been described primarily with reference to specific embodiments, the material, structure, and other details of the above-described embodiments have been described without departing from the scope of the technical idea and purpose of the present invention. In this configuration, those skilled in the art can make various modifications.
Therefore, the descriptions of the materials and structures disclosed above are exemplary for ease of understanding of the present invention, and do not limit the present invention. Descriptions with names excluding some or all of the limitations are included in the present invention.

For example, in this embodiment, the tension control by the tension control device 50 is performed by the vertical movement of the dancer roll 52, but the tension control method is not limited thereto. For example, it may be performed by controlling the winding speed (winding force) of the film 3 by the winding device 60.
Moreover, in this embodiment, although the tubular system was employ | adopted as a biaxial stretching method, a tenter system may be used. Furthermore, the stretching method may be simultaneous biaxial stretching or sequential biaxial stretching.

Next, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to these examples. In addition, the same code | symbol as the code | symbol of the figure in embodiment was used for the location which is common as an apparatus.
[Examples 1-5, Comparative Examples 1-6]
In the above-described embodiment (FIG. 1), the biaxially stretched nylon film 3 was manufactured by setting specific conditions.
As a crystalline thermoplastic resin, polyamide-based nylon 6 (relative viscosity 3.7) is used, melt-extruded from an annular die having a diameter of 60 mm, and then rapidly cooled in cooling water at 15 ° C. to obtain a diameter of 90 mm and a thickness of 120 μm or A 200 μm original fabric film 1 (tubular nylon film, shrinkage starting temperature 45 ° C., melting point 215 ° C.) was produced. While the original film 1 is heated using an infrared heater in the tubular stretching apparatus 10, simultaneous biaxial stretching is performed at a stretching ratio MD (film moving direction) / TD (orthogonal direction) = 3.0 / 3.2. Thus, a film 2 was obtained.
Next, the film 2 was continuously supplied to the guide plate 11 and the pinch roll 12 and folded to obtain a flat tube-like film 2.

Next, this flattened film 2 was sent to a preliminary heat treatment apparatus (preheating furnace) 20, where the film 2 was preheated at 60 ° C. for 5 seconds, and preliminarily processed. Inside the preheating furnace 20 are disposed clips (not shown) that run while gripping the ends of the film 2 on the left and right.
Next, after incising both ends of the flat film 2 with a trimming device 32 attached to the separation device 30 to separate the two films 2A and 2B, the films 2A and 2B are separated with separation rollers 33A and 33B. The inner surfaces were separated from each other and brought into contact with air, and then overlapped again by passing between the grooved rolls 34A to 34C.

Next, the films 2A and 2B were introduced into the heat treatment apparatus 40. Specifically, while holding both ends of the films 2A and 2B with a tenter 41 provided with a clip, heat treatment (heat setting) is performed at 210 ° C. for 10 seconds, and the biaxially stretched nylon film 3 (having stable physical properties) Films 3A and 3B) were obtained. During this heat setting, the tension T shown in Table 1 is applied to the films 2 and 3 by the tension control device 50 located downstream.
Next, the heat-fixed film 3 was wound up into two pieces (films 3A and 3B) using a winding device 60.
Two types of films 3 having a thickness of 15 μm (Examples 1 to 3 and Comparative Examples 1 to 4) and 25 μm (Examples 4 and 5 and Comparative Examples 5 and 6) were produced.
Here, the tension T described in Table 1 is a value converted per film width of 1 m and film thickness of 15 μm.

[Evaluation methods]
In the above Examples and Comparative Examples, the moldability during film 3 production (formability during heat treatment) was evaluated, and the degree of bowing phenomenon (Boeing rate) and the degree of tarmi (the disappearance of tarmi) in the obtained film 3 Tension), smoothness, and printability were evaluated, and the results are shown in Table 1.

(Formability during heat treatment)
The film 2 when subjected to heat treatment in the heat treatment apparatus 40 of FIG. 1 was observed, and the formability was evaluated as follows.
○: Even when the time (operation time) during which the film 2 is continuously subjected to heat treatment passes 12 hours, the film 2 is not broken or detached from the clip in the heat treatment apparatus 40.
Δ: The operation time is about 12 hours, and the film 2 is broken or detached from the clip (operation stop).
X: The film 2 is broken or detached from the clip after an operation time of about 2 to 3 hours (operation stop).

(Boeing rate)
As shown in FIG. 3, a marked line S having a predetermined width is drawn on the original film 1 in a direction perpendicular to the moving direction, and a delay amount ΔB at the center of the marked line S of the film 3 after stretching and heat treatment The width L was measured, and the value obtained by the following formula (3) was taken as the bowing rate (%).
Boeing rate (%) = ΔB / L × 100 (3)

(Tarmi disappearance tension)
About 500 m was sampled while slitting the 1 m wide film 3 from the end of the wide film 3 wound up by the winding device 60. Then, the tarmi disappearance tension (N) was measured in the following manner while rewinding using a tarmi amount measuring device (small slitter) 70 as shown in FIG.
The roll-rolled film 3 set on the feed roll 71 was rewinded by the take-up roll 73 via the intermediate rolls 72A and 72B while being fed at about 20 m / min. At that time, the tension applied to the film 3 was controlled by applying a brake to the feeding roll 71.
If there is a tarmi at the end of the film 3, the end will flutter while running, but the fluttering will subside as the tension is increased. Therefore, the tension when the fluttering at the end of the film 3 is reduced is defined as the tarmi disappearance tension. Specifically, the flapping of the end SAG between the feeding roll 71 and the intermediate roll 72A (about 50 cm) was observed. The tarmi disappearance tension was shown as a value (N) converted per 1 m width and 15 μm thickness of the film 3.

(Smoothness)
In Example 1, it was used by Examples 1-5 and Comparative Examples 1-6 by using the talmi disappearance tension (64.7 N / 1m width and 15 μm thickness) measured by the above-described talmi amount measuring device 70 as a reference tension. The smoothness of each film 3 was measured. Specifically, using the tarmi amount measuring device 70, each of the roll-wrapped films 3 of Examples 1 to 5 and Comparative Examples 1 to 6 is subjected to a rewinding operation for about 1 minute while applying a reference tension. The smoothness was judged on the basis of
○: No fluttering can be confirmed on the end SAG of the film 3 Δ: Some fluttering can be confirmed on the end SAG of the film 3 ×: The fluttering can be clearly confirmed on the end SAG of the film 3

(Printability)
The film 3 after biaxial stretching and heat treatment was printed (5 colors) on a commercial multicolor printing machine under normal operating conditions. Printing suitability was judged according to the following criteria depending on whether or not a so-called pitch shift occurred during printing due to fluttering due to tarmi at the film edge during running.
○: Print pitch deviation within 0.5 mm, no problem in practical use Δ: Print pitch deviation of about 1 mm was recognized, but could be accommodated by adjustment of printing press ×: Print pitch deviation of 1 mm or more Yes, it was difficult to adjust the printing press

[Evaluation results]
As shown in Table 1, in the examples, since the tension by the tension control device is within a predetermined range, the moldability of the film 2 in the heat treatment is good, and the bowing rate of the film 3 after the heat treatment is also low. Also, tarmi disappearance tension is low. As a result, the film 3 is excellent in smoothness and has no problem in printability. In addition, although the thickness of the film 3 was 15 micrometers in Examples 1-3 and 25 micrometers in Examples 4, 5, all obtained a favorable result.

On the other hand, since the comparative examples do not satisfy the above-described conditions, both have problems. Specifically, Comparative Examples 1, 3, and 5 have a high bowing rate of the film 3 after heat setting because the tension T is very low on the film 2 during heat treatment. Therefore, the tarmi disappearance tension is high and the printability is poor. In Comparative Example 6, the tension T is set to be relatively high, but it is still less than 98N and out of the scope of the present invention, so that the smoothness and printability of the film 3 are insufficient.
In Comparative Examples 2 and 4, on the contrary, the tension T is very high and the bowing rate is low, so the tarmi disappearance tension is low and the printability is excellent. However, the tension T exceeds the range of the present invention, and during the heat treatment, breakage tends to occur in the vicinity of the clip inside the tenter 41, and there is a problem in formability.

INDUSTRIAL APPLICABILITY The present invention can be used as a method for producing a biaxially stretched nylon film with little talmi at the end and a biaxially stretched nylon film production apparatus therefor.

Schematic of the biaxially stretched film manufacturing apparatus which concerns on embodiment of this invention. Schematic of the tension control device in the embodiment. The schematic diagram which shows the bowing rate measuring method which concerns on the Example of this invention. The perspective view of the amount measurement apparatus of the talmi in the said Example.

Explanation of symbols

1 Unstretched film 2 Base film 3 Biaxially stretched film (biaxially stretched nylon film)
10 Biaxial stretching equipment (tubular biaxial stretching equipment)
20 Pre-heat treatment equipment (pre-heating furnace)
30 Separation apparatus 40 Heat treatment apparatus 50 Tension control apparatus 60 Winding apparatus 70 Tarmi amount measuring apparatus 100 Biaxially stretched film manufacturing apparatus

Claims (7)

A biaxially stretched nylon film production method comprising a biaxially stretched step and a heat treatment step performed thereafter,
The raw material of the biaxially stretched nylon film is nylon 6,
A method for producing a biaxially stretched nylon film, wherein a tension T shown in the following formula (1) is applied to a base film that has been subjected to a heat treatment in the heat treatment step from the downstream side while gripping an end thereof.
118 ≦ T ≦ 196 (1)
(In the formula, T represents the tension per 1 m width and 15 μm thickness of the base film. The unit is N.) In the manufacturing method of the biaxially stretched nylon film of Claim 1,
The method for producing a biaxially stretched nylon film, wherein the tension is controlled by a tension control device provided downstream of the heat treatment step. In the manufacturing method of the biaxially stretched nylon film of Claim 2,
The method for producing a biaxially stretched nylon film, wherein the tension control device includes a dancer roll. In the manufacturing method of the biaxially stretched nylon film in any one of Claims 1-3,
The method for producing a biaxially stretched nylon film, wherein the heat treatment step includes a preliminary heat treatment step and a subsequent heat treatment step. In the manufacturing method of the biaxially stretched nylon film in any one of Claims 1-4,
A method for producing a biaxially stretched nylon film, wherein the biaxial stretching is a tubular system. A biaxially stretched nylon film manufacturing device including a biaxially stretched device and a heat treatment device,
The raw material of the biaxially stretched nylon film is nylon 6,
A tension control device is provided downstream of the heat treatment device,
The tension control device applies a tension represented by the following formula (1) from the downstream side to the base film that is subjected to the heat treatment while being gripped at the end inside the heat treatment device. Nylon film manufacturing equipment.
118 ≦ T ≦ 196 (1)
(In the formula, T represents the tension per 1 m width and 15 μm thickness of the base film. The unit is N.) In the biaxially stretched nylon film manufacturing apparatus according to claim 6,
The biaxially stretched nylon film manufacturing apparatus, wherein the tension control device includes a dancer roll.

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