JP2014124947A - Biaxially stretched nylon film, laminate film, laminate packaging material, and method for manufacturing a biaxially stretched nylon film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxially stretched nylon film not only exhibiting an excellent deep draw moldability on a cold molding occasion but also having high strengths; a laminate film; a laminate packaging material; and a method for manufacturing a biaxially stretched nylon film.SOLUTION: The biaxially stretched nylon film of the present invention is a biaxially stretched nylon film using a nylon resin as a raw ingredient in which the degree of crystallization of the film is 34% or above and 39% or below and in which the piercing strength thereof is at least 17.0 N/25 μm.

Description

  In particular, the present invention relates to a biaxially stretched nylon film, a laminate film, a laminate packaging material, and a method for producing a biaxially stretched nylon film that can be suitably used as a packaging material for cold forming.

Biaxially stretched nylon film (hereinafter also referred to as ONy film) is excellent in strength, impact resistance, pinhole resistance, etc., and is therefore often used for applications that require heavy strength loads such as heavy weight packaging and water packaging. .
And as a packaging material for cold molding, the laminate packaging material containing this ONy film is superior to hot molding in safety and shape flexibility (deep drawing moldability), and can be made thinner and lighter. A biaxially stretched nylon film suitable for cold forming applications has been developed (for example, Patent Document 1). A laminate packaging material including such an ONy film can be suitably used for battery packaging or pharmaceutical packaging.

Japanese Patent Laid-Open No. 2008-4516

  However, in recent years, with further reduction in thickness and weight of laminate products, deep drawability and strength under more severe conditions are required. Therefore, the laminate packaging material including the biaxially stretched nylon film described in Patent Document 1 still has room for improvement from the viewpoint of obtaining better deep drawability.

  Accordingly, the present invention provides a biaxially stretched nylon film, a laminate film, a laminate packaging material, and a method for producing a biaxially stretched nylon film, which have excellent deep drawability at the time of cold molding and high strength. With the goal.

  In the present invention, cold molding refers to molding performed at room temperature without heating. One means of such cold forming is to use a cold forming machine used for forming aluminum foil or the like to push the sheet material into the female mold with a male mold and press it at high speed. According to such cold forming, plastic deformation such as molding, bending, shearing and drawing can be generated without heating.

  As a result of intensive studies to solve the above problems, the present inventors have found that there is a correlation between the degree of crystallinity and puncture strength of the film and the deep drawability, and have completed the present invention. It was.

That is, the gist of the present invention is as follows.
(1) A biaxially stretched nylon film containing nylon 6 as a raw material, wherein the film has a crystallinity of 34% or more and 39% or less and a puncture strength of 17.0 N / 25 μm or more. Biaxially stretched nylon film.
(2) The biaxially stretched nylon film as described in (1) above, which is for cold forming.
(3) A laminate film obtained by laminating the biaxially stretched nylon film described in (1) or (2) above.
(4) A laminate packaging material using the laminate film described in (3) above.
(5) A method for producing a biaxially stretched nylon film as described in (1) or (2) above, wherein a raw film production process for forming a raw film from the raw material, and an MD direction (film movement) Direction) and TD direction (film width direction) are each 2.8 times or more, and the maximum strain rate in the MD direction and TD direction is 2.5 s ⁻¹ or more, respectively. A biaxial stretching step of stretching the anti-film, and a heat fixing step of heat-setting the film after the biaxial stretching step by heat treatment at a heat treatment temperature of 170 ° C. or higher and 210 ° C. or lower. A method for producing an axially stretched nylon film.
(6) The biaxially stretched nylon film described in (5) above, wherein the biaxially stretched nylon is biaxially stretched by a tubular biaxial stretch method in the biaxially stretched step. A method for producing a film.

  According to the present invention, there are provided a biaxially stretched nylon film, a laminate film, a laminate packaging material, and a method for producing a biaxially stretched nylon film, which have excellent deep drawability during cold molding and high strength. Can do.

It is a schematic block diagram which shows an example of the apparatus which manufactures the biaxially stretched nylon film of this invention.

Hereinafter, an embodiment of the present invention will be described in detail.
[Configuration of biaxially stretched nylon film]
A biaxially stretched nylon film (hereinafter also referred to as “ONy film”) according to the present embodiment is obtained by biaxially stretching an unstretched raw film made of nylon 6 (hereinafter also referred to as “Ny6”) as a predetermined material. It was formed by heat treatment (heat setting) at a temperature of Thus, an ONy film excellent in impact resistance can be obtained by biaxially stretching an unstretched raw film.
Here, the chemical formula of Ny6 is shown in the following formula (1).

The number average molecular weight of the raw material nylon resin is preferably 15000 or more and 30000 or less, and more preferably 22000 or more and 24000 or less.
If the number average molecular weight of the nylon resin is less than 15000, impact strength and tensile strength may be insufficient. If it exceeds 30000, a load in extrusion molding is excessively applied and it is difficult to obtain an appropriate extrusion amount. Efficiency may be reduced.

  The ONy film according to this embodiment needs to have a crystallinity of 34% or more and 39% or less, preferably 35% or more and 38% or less, and the pin puncture strength of the film is 17.0 N / 25 μm. As mentioned above, Preferably, it needs to be 17.5N / 25micrometer or more. By setting the crystallinity and puncture strength of the film within the above predetermined ranges, it is possible to obtain an ONy film that has higher strength and better deep drawability than a normal ONy film. It is possible to prevent breakage of the ONy film and occurrence of pinholes. When the degree of crystallinity of the film is less than 34%, shrinkage and delamination (delamination within the layer) are likely to occur as compared with a normal ONy film, and there may be a problem during molding. On the other hand, if the crystallinity of the film exceeds 39%, cold drawability is lowered. Moreover, when the puncture strength of the film is less than 17.0 N / 25 μm, there arises a problem that deep drawing cannot be stably performed.

A method for measuring the crystallinity and the puncture strength will be described later.
In addition, it can implement | achieve by adjusting the draw ratio at the time of ONy film manufacture, the maximum strain rate, and the heat setting temperature after extending | stretching as a means which makes the crystallinity and puncture strength of an ONy film the above-mentioned range.

[Composition of laminate film]
The laminate film of this embodiment is configured by laminating one or two or more other laminate base materials on at least one surface of the above-described ONy film. Specifically, examples of other laminate base materials include an aluminum layer, a stainless steel layer, a film including these layers, and a polypropylene-based or polyethylene-based seal layer (sealant layer).
In addition, the laminate packaging material of the present embodiment is made of polyethylene terephthalate (PET), polyester resin, polyvinylidene chloride resin, polyvinylidene chloride copolymer resin, lubricant, on at least one surface of the above-mentioned ONy film, A laminate in which an antistatic agent or a coating layer of nitrified cotton amide resin is further laminated may be used.
By laminating such a laminate substrate, it is possible to improve manufacturing efficiency and conveyance efficiency, and functionality (chemical resistance, electrical insulation, moisture resistance, cold resistance, workability, etc.) Can be obtained.
As a lamination | stacking aspect of the said laminate film, ONy / Al (SUS) / PP, PET / ONy / Al (SUS) / PP, ONy / Al / PVC is mentioned, for example.

[Composition of laminate packaging material]
The laminate packaging material of this embodiment is comprised from the said laminate film. In general, a laminate packaging material including an aluminum layer is not suitable for cold forming because the aluminum layer is easily broken by necking during cold forming. In this regard, according to the laminate packaging material of the present embodiment, the above-described ONy film has excellent deep-drawing moldability, so that it is possible to suppress the breakage of the aluminum layer during cold-drawing, etc. Generation of pinholes in the material can be suppressed. Therefore, even when the total thickness of the packaging material is thin, a molded product having a sharp shape and high strength can be obtained.

  The laminate packaging material of this embodiment preferably has an overall thickness of the ONy film and other laminate base material of 200 μm or less. When the total thickness exceeds 200 μm, it becomes difficult to form the corner portion by cold forming, and it tends to be difficult to obtain a molded product having a sharp shape.

  The thickness of the ONy film in the laminate packaging material of this embodiment is preferably 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 30 μm or less. Here, if the thickness of the ONy film is less than 5 μm, the impact resistance of the laminate packaging material tends to be low, and the cold formability tends to be insufficient. On the other hand, when the thickness of the ONy film exceeds 50 μm, it is difficult to obtain an effect of further improving the impact resistance of the laminate packaging material, which is not preferable because the total thickness of the packaging material is increased.

[Production equipment for biaxially stretched nylon film]
Next, a method for producing the biaxially stretched nylon film of the present embodiment will be described based on the drawings.
First, an apparatus for producing the biaxially stretched nylon film of this embodiment will be described with an example.
As shown in FIG. 1, the film manufacturing apparatus 100 includes an original fabric manufacturing apparatus 90 for manufacturing the original fabric film 1, a biaxial stretching apparatus (tubular stretching apparatus) 10 that stretches the original fabric film 1, and stretching. A first heat treatment device 20 (preheating furnace) that preheats a base film 2 that is folded later (hereinafter also simply referred to as “film 2”), a separation device 30 that separates the preheated film 2 into two upper and lower sheets, A second heat treatment device 40 that heat-treats (heat-set) the separated film 2, a tension control device 50 that applies tension to the film 2 from the downstream side when the film 2 is heat-set, and the film 2 is heat-set. And a winding device 60 for winding the biaxially stretched nylon film 3 (hereinafter also simply referred to as “film 3”).

As shown in FIG. 1, the raw fabric manufacturing apparatus 90 includes an extruder 91, a circular die 92, a water cooling ring 93, a stabilizer plate 94, and a pinch roll 95.
The tubular stretching device 10 is a device for producing a film 2 by biaxially stretching (bubble stretching) a tubular raw film 1 with the pressure of internal air. As shown in FIG. 1, the tubular stretching device 10 includes a pinch roll 11, a heating unit 12, a guide plate 13, and a pinch roll 14.
The first heat treatment apparatus 20 is an apparatus for preliminarily heat-treating the flat film 2. As shown in FIG. 1, the first heat treatment apparatus 20 includes a tenter 21 and a heating furnace 22.
As shown in FIG. 1, the separating device 30 includes a guide roll 31, a trimming device 32, separating rolls 33A and 33B, and grooved rolls 34A to 34C. Further, the trimming device 32 has a blade 321.

The second heat treatment apparatus 40 includes a tenter 41 and a heating furnace 42 as shown in FIG.
As shown in FIG. 1, the tension controller 50 includes guide rolls 51 </ b> A and 51 </ b> B and a tension roll 52.
As shown in FIG. 1, the winding device 60 includes a guide roll 61 and a winding roll 62.

[Production method of biaxially stretched nylon film]
Next, each process which manufactures a biaxially-stretched nylon film using this film manufacturing apparatus 100 is demonstrated in detail.

(Raw film production process)
As shown in FIG. 1, the raw material nylon resin is melt-kneaded by an extruder 91 and extruded into a tube shape by a circular die 92. The tubular molten resin is cooled by a water cooling ring 93. The raw film 1 is molded by rapidly cooling a molten nylon resin as a raw material by a water cooling ring 93. The cooled original film 1 is folded by the stabilizer 94. The folded original fabric film 1 is sent to the next biaxial stretching process by a pinch roll 95 as a flat film.

(Biaxial stretching process)
As shown in FIG. 1, the original film 1 manufactured by the original film manufacturing process is introduced into the apparatus as a flat film by a pinch roll 11. The introduced raw film 1 is bubble-stretched by being heated with infrared rays at the heating unit 12. Thereafter, the film 2 after being bubble-stretched is folded by the guide plate 13. The folded film 2 is pinched by the pinch roll 14 and sent to the next first heat treatment step as a flat film 2.

  At this time, the draw ratios in the MD direction and the TD direction must be 2.8 times or more, respectively. When either the MD direction or TD direction draw ratio is less than 2.8 times, the strength of the resulting film is lowered, causing a problem in practicality.

Further, it is necessary that the maximum strain rates in the MD direction and the TD direction are 2.5 s ⁻¹ or more, respectively. When either the maximum strain rate in the MD direction or the TD direction is less than 2.5 s ⁻¹ , the desired film crystallinity and puncture strength cannot be imparted to the resulting film, and the film strength or deep drawability Is lacking. Further, from the viewpoint of further improving deep drawability, the maximum strain rate is more preferably 3.0 s ⁻¹ or more.
The strain rate refers to the rate of increase in magnification per time.

The maximum strain rate can be obtained by the following method.
First, a film sample in the middle of stretching is collected. Then, a change in the folding diameter (width) of the sample with respect to the moving distance in the moving direction of the sample is measured, and a curve indicating the relationship between the moving distance and the folding diameter (width) of the sample is created. Here, the time from the start of stretching can be calculated from the moving distance. Moreover, the relationship between the folding diameter of the sample, the folding diameter (width) of the raw film (unstretched film), and the stretching ratio in the TD direction is expressed by the following formula:
(Folded diameter of sample (width)) / (Folded diameter of raw film (width)) = (Stretch ratio in TD direction)
Therefore, by dividing the folding diameter (width) of the sample by the folding diameter (width) of the original film, the stretching ratio in the TD direction can be calculated. Therefore, a curve indicating the relationship between the time from the start of stretching and the stretching ratio in the TD direction can be created from a curve indicating the relationship between the moving distance and the folding diameter of the sample.
Next, for the sample described above, a change in the thickness of the sample with respect to the moving distance in the moving direction of the sample is measured, and a curve indicating the relationship between the moving distance and the thickness of the sample is created. Here, the time from the start of stretching can be calculated from the moving distance. Moreover, the relationship between the thickness of the sample, the thickness of the raw film, and the overall draw ratio of MD × TD is expressed by the following formula:
(Thickness of original film) / (Thickness of sample) = (Total draw ratio of MD × TD)
Therefore, the total draw ratio of MD × TD can be calculated by dividing the thickness of the sample from the thickness of the raw film. Moreover, the relationship between the MD × TD total draw ratio, the TD direction draw ratio, and the MD direction draw ratio is given by the following formula:
(MD × TD total draw ratio) / (TD direction draw ratio) = (MD direction draw ratio)
Therefore, by dividing the TD-direction stretch ratio calculated from the MD × TD total stretch ratio, the MD-direction stretch ratio can be calculated. Therefore, a curve indicating the relationship between the time from the start of stretching and the stretching ratio in the MD direction can be created from the curve indicating the relationship between the moving distance and the thickness of the sample.
With the two curves that can be created as described above, the change state of the draw ratio in the MD direction and the TD direction with respect to the time from the start of drawing can be quantified. In these curves, the maximum strain rate in the MD direction and the TD direction can be obtained by obtaining the slope of the portion where the slope of the curve is maximum.

  Furthermore, it is preferable that the stretching ratio in the TD direction is larger than the stretching ratio in the MD direction at the end of stretching. Further, the difference (TD-MD) obtained by subtracting the draw ratio in the MD direction from the draw ratio in the TD direction is preferably 0.1 to 0.8 times, and more preferably 0.2 to 0.8 times. It is more preferable that it is 0.3 times or more and 0.8 times or less. If the value of TD-MD is less than the above lower limit, the deep drawability of the resulting film tends to be insufficient, and the thickness accuracy of the film tends to be lowered. In particular, when the value of TD-MD is 0.1 times or less, the stretching stability is inferior and the thickness accuracy of the film tends to be lowered. On the other hand, when the value of TD-MD exceeds the upper limit, the deep drawability of the resulting film tends to be insufficient, and the stretching stability is lowered.

(First heat treatment process)
The film 2 sent from the biaxial stretching step is at or above the shrinkage start temperature of the film 2 and about 30 ° C. higher than the melting point of the film 2 while being gripped at both ends by clips (not shown) of the tenter 21. The film 2 is preheated at a low temperature or lower and sent to the next separation step.
The heat treatment temperature in the first heat treatment is preferably 120 ° C. or higher and 190 ° C. or lower, and the relaxation rate is preferably 15% or lower.
By this first heat treatment step, the crystallinity of the film 2 is increased, and the slipping property between the overlapping films is improved.

(Separation process)
As shown in FIG. 1, the flat film 2 sent through the guide roll 31 is cut into both ends by a blade 321 of a trimming device 32 and separated into two films 2A and 2B. And film 2A, 2B is isolate | separated, interposing air between film 2A, 2B by a pair of separation roll 33A, 33B located up and down apart. 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. , It may be performed so that the ear does not occur.
These films 2A and 2B are overlapped again by three grooved rolls 34A to 34C positioned in order in the film flow direction, and sent to the next second heat treatment step. In addition, these grooved rolls 34A to 34C are obtained by plating the surface after the grooved processing. A good contact state between the films 2A and 2B and the air can be obtained through the grooves.

(Second heat treatment process (heat setting process))
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. It is (heat-set) and becomes a biaxially stretched nylon film 3 (hereinafter also referred to as film 3) having stable physical properties, and is sent to the next winding step.
The heat treatment temperature in the second heat treatment (heat setting) needs to be 170 ° C. or higher and 210 ° C. or lower. When the heat treatment temperature is less than the lower limit, the film shrinkage rate is increased, and the risk of delamination is increased.On the other hand, when the upper limit is exceeded, the bowing phenomenon at the time of heat setting increases, and the distortion of the film increases. The density becomes too high, the crystallinity becomes too high, and the film is difficult to deform.
In addition, the relaxation rate at this time is preferably 15% or less.
A strong tension is applied to the films 2A and 2B in the heating furnace 42 by the tension control device 50 located on the downstream side.

(Winding process)
The film 3 heat-set in the second heat treatment step is wound as films 3A and 3B on the two winding rolls 62 via the guide roll 61 via the tension control device 50.

[Modification of Embodiment]
The aspect described above shows one aspect of the present invention, and the present invention is not limited to the above-described embodiment, and has the configuration of the present invention and can achieve the object and effect. It goes without saying that modifications and improvements within the scope are included in the content of the present invention. In addition, the specific structure and shape in carrying out the present invention may be used as other structures and shapes within the scope of achieving the object and effect of the present invention.

  For example, in this embodiment, the tubular method is adopted as the biaxial stretching method, but a tenter method 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.

[Example 1]
(Raw film production process)
As shown in FIG. 1, after Ny6 pellets were melt-kneaded at 270 ° C. in an extruder 91, the melt was extruded as a tubular film from a circular die 92, and then rapidly cooled with water (15 ° C.). Film 1 was produced.
What was used as Ny6 is Ube Industries, Ltd. nylon 6 [UBE nylon 1022FD (trade name), relative viscosity ηr = 3.5].
(Biaxial stretching process)
Next, as shown in FIG. 1, the raw film 1 is inserted between a pair of pinch rolls 11, and then heated by the heating unit 12 while a gas is being pressed into the film 1, and blown to the stretching start point to form bubbles. The biaxial stretching in the MD direction and the TD direction was performed by the tubular method by expanding and taking up with a pair of downstream pinch rolls 14. The magnification during this stretching was 3.0 times in the MD direction and 3.4 times in the TD direction. The maximum strain rate during the stretching was ^{5.0 s} -1, 4.0 s ^-1 at TD direction MD direction.
(First heat treatment step and second heat treatment step)
Next, as shown in FIG. 1, the film 2 is subjected to heat treatment at a temperature of 170 ° C. by the first heat treatment apparatus 20, and then passed through the separation apparatus 30 and then heat treated at a temperature of 203 ° C. by the second heat treatment apparatus 40. And heat fixed.
In Example 1, the puncture strength was 17.9 N / 25 μm, the crystallinity was 34.2%, and the film thickness was 25 μm.
(Winding process)
Next, as shown in FIG. 1, the film 3 heat-set in the second heat treatment step 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. A biaxially stretched nylon film was produced. The thickness of the obtained biaxially stretched nylon film was 25 μm.
(Production of laminate film)
The obtained biaxially stretched nylon film was used as a front substrate film, an aluminum foil having a thickness of 40 μm was used as an intermediate substrate, and a CPP film having a thickness of 60 μm was used as a sealant film to obtain a laminate film. The laminated film after dry lamination was aged at 40 ° C. for 3 days.

[Example 2]
The stretch ratio, 3.0 times in MD direction and 3.2 times in TD direction, ^{3.5 s} the maximum strain rate in the MD direction -1, and 3.0 s ^-1 at TD direction, and 207 ° C. The heat treatment temperature The same production as in Example 1 was carried out except that. In Example 2, the puncture strength was 17.5 N / 25 μm, the crystallinity was 36.3%, and the film thickness was 25 μm.

Example 3
The stretch ratio, 3.0 times in MD direction and 3.3 times in TD direction, ^5.3S the maximum strain rate in the MD direction -1, and 4.2 s ^-1 at TD direction, and 205 ° C. The heat treatment temperature The same production as in Example 1 was carried out except that. In Example 3, the puncture strength was 17.7 N / 25 μm, the crystallinity was 35.3%, and the film thickness was 25 μm.

Example 4
The stretch ratio, 3.0 times in MD direction and 3.5 times in TD direction, ^3.8S the maximum strain rate in the MD direction -1, and 3.5 s ^-1 at TD direction, and 208 ° C. The heat treatment temperature The same production as in Example 1 was carried out except that. In Example 4, the puncture strength was 18.1 N / 25 μm, the crystallinity was 37.2%, and the film thickness was 25 μm.

Example 5
The stretch ratio, 3.1 times in MD direction and 3.4 times in TD direction, ^{4.0 s} the maximum strain rate in the MD direction -1, and 4.1S ^-1 in the TD direction, and 210 ° C. The heat treatment temperature The same production as in Example 1 was carried out except that. In Example 5, the puncture strength was 17.2 N / 25 μm, the crystallinity was 38.4%, and the film thickness was 25 μm.
[Comparative Examples 1-6]
As Comparative Examples 1 and 2, with the production method shown in Example 1, the production conditions (stretch ratio, maximum strain strength, heat setting temperature, thickness) were appropriately adjusted as shown in Table 1 below, and biaxially oriented nylon Films and laminate films were prepared.
On the other hand, as Comparative Examples 3 to 6, with the production methods shown in Table 1 below, the production conditions (stretch ratio, maximum strain strength, heat setting temperature, thickness) were appropriately adjusted as shown in Table 1 below. A stretched nylon film and a laminate film were produced.

〔Evaluation method〕
In the above examples and comparative examples, the obtained biaxially stretched nylon film and laminate film were evaluated for density, crystallinity, puncture strength, stretch moldability, thickness accuracy, and drawability, and the results Are shown in Table 1.

(density)
The density was measured by measuring the obtained film with a dry automatic densimeter “Acupic 1330” (manufactured by Shimadzu Corporation).

(Crystallinity)
The crystallinity χc is measured from the density of the obtained film according to the following equation.
χc (%) = dc (d−da) / d (dc−da) × 100
d: film density (measured value)
dc: density of crystal region (reference value 1212)
da: density of amorphous region (reference value 1113)

(Puncture strength)
The puncture strength was measured by piercing a 1 mmφ needle at a piercing speed of 200 mm / min on the obtained film and measuring the strength (N) required for the needle to penetrate the film. .

(Stretch formability)
The stretch moldability was evaluated based on the following evaluation criteria by measuring the film folding width continuously during film formation, and the variation rate.
In addition, the definition of bubble rupture folding diameter fluctuation rate was as follows.
{(Maximum film folding diameter-film minimum folding diameter) / 2 / film average folding diameter} × 100%
A: The film folding diameter fluctuation rate is 2.0% or less.
X: Film folding diameter fluctuation rate exceeds 2.0%.

(Thickness accuracy)
The thickness accuracy was measured based on the following evaluation criteria by measuring the thickness every 1 cm in the width direction of the obtained film and measuring the thickness accuracy (%).
In addition, the definition of thickness accuracy was as follows.
{(Maximum film thickness-minimum film thickness) / 2 / average film thickness} × 100%
A: Thickness accuracy is less than 4.5%.
X: Thickness accuracy is 4.5% or more.

(Drawing formability)
The drawability is determined by first cutting the laminate wrapping material to prepare a 120 × 80 mm strip and using it as a sample and pressing it with a surface pressure of 0.1 MPa using a 33 × 55 mm rectangular mold. The molding depth was changed in units of 0.5 mm from the molding depth of 0.5 mm, and cold molding (retraction one-stage molding) was performed on each of 10 samples. The molding depth at which no pinhole was generated in the aluminum foil in any of the 10 samples was defined as the limit molding depth, and the molding depth was shown as an evaluation value.
In addition, confirmation of the pinhole confirmed the transmitted light visually.
A: The limit molding depth is 5 mm or more.
X: The limit molding depth is less than 5 mm.

As is clear from the results shown in Table 1, when the crystallinity and puncture strength of the biaxially stretched nylon film satisfy the above conditions (Examples 1 to 5), the film has high film strength and is cold-molded. Sometimes it has been found to have good deep drawability. Moreover, it was confirmed that these biaxially stretched nylon films have good stretch moldability and excellent film thickness accuracy.
On the other hand, in the case where the crystallinity and puncture strength of the biaxially stretched nylon film do not satisfy the above conditions (Comparative Examples 1 to 6), good deep drawing moldability is insufficient at the time of cold molding and the film strength is insufficient. It was confirmed that there was. Furthermore, these biaxially stretched nylon films have insufficient stretch moldability and film thickness accuracy, and the deep drawability of the laminate film is also insufficient.

  The biaxially stretched nylon film of the present invention is, for example, for industrial fields (such as lithium battery packaging materials mounted on electric vehicles, tablet-type terminal devices, smartphones, etc.), pharmaceutical fields (PTP packaging materials, etc.), household goods. It can be suitably used as a packaging material that particularly requires pinhole resistance, such as packaging materials in the field (such as refill packaging for liquid detergents) and foods. The laminate packaging material of the present invention can be suitably used as a packaging material for cold molding that requires particularly excellent deep drawability.

    3, 3A, 3B ... Biaxially stretched nylon film

Claims (6)

A biaxially stretched nylon film containing nylon 6 as a raw material,
A biaxially stretched nylon film, wherein the film has a crystallinity of 34% or more and 39% or less and a puncture strength of 17.0 N / 25 μm or more. In the biaxially stretched nylon film according to claim 1,
A biaxially stretched nylon film characterized by being for cold forming.   A laminate film comprising the biaxially stretched nylon film according to claim 1 or 2 laminated.   A laminate packaging material using the laminate film according to claim 3. A method for producing the biaxially stretched nylon film according to claim 1 or 2,
A raw film manufacturing process for forming a raw film from the raw material,
The stretching ratio in the MD direction (film movement direction) and TD direction (film width direction) is 2.8 times or more, respectively, and the maximum strain rate in the MD direction and TD direction is 2.5 s ⁻¹ or more, respectively. Under certain conditions, a biaxial stretching step of stretching the raw film,
A heat setting step of heat-setting the film after the biaxial drawing step at a heat treatment temperature of 170 ° C. or higher and 210 ° C. or lower. In the manufacturing method of the biaxially stretched nylon film of Claim 5,
In the biaxial stretching step, biaxial stretching is performed by a tubular biaxial stretching method. A method for producing a biaxially stretched nylon film.