JP2018135114A - Packaging film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a packaging film allowing increase of a gas permeation amount according to the user's requirement, and having excellent MA packing effect.SOLUTION: A packaging film has a gas permeation part in a plastic film substrate 11, allowing permeation of gas. The gas permeation part comprises one slit row 12L formed by arranging multiple first slits 12A that are formed by recessing the film substrate 11 by a predetermined depth from one face to the other face to expand bottom parts outward from the other surface, and are formed to have the thinnest thickness at the bottom parts by gradually thinning from openings toward the bottom parts, and multiple second slits 12B having through-holes drilled on the bottom parts of the slits. On the slit row, the number of the first slits 12A is set larger than the number of the second slits 12B by dozens of times and mixedly arranged in the film substrate 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a packaging film, and more particularly, to a packaging film suitable for MA packaging (Modified Atmosphere Packaging), for example, for packaging fresh fruits and vegetables such as vegetables and fruits while maintaining freshness.

  The present applicant has developed a gas permeable film that can be used in a wide range of fields, for example, a packaging film suitable for MA packaging, and has already obtained a patent of Patent Document 1 below.

  Hereinafter, with reference to FIG. 8, the gas-permeable film described in Patent Document 1 below will be described. 8 shows a gas permeable film, FIG. 8 is a plan view, and FIG. 8B is a cross-sectional view taken along line VIIIB-VIIIB in FIG. 8A.

The gas permeable film described in Patent Document 1 below has the following characteristics.
(A) Configuration The gas permeable film 1 is a film in which a gas permeable portion 3L that allows gas (hereinafter also referred to as gas) to pass through a plastic film substrate 2 having a predetermined thickness is provided. The film base 2 is composed of an unpenetrated recess 3 that is recessed from the one surface to the other surface by a predetermined depth and the bottom is bulged outward from the other surface. The recess 3 is formed from the upper opening 3a. The thickness of the body 3b is gradually reduced toward the bottom 3c, and the bottom 3c is formed to be the thinnest.

  The recess 3 is a discontinuous slit row or a relatively long continuous slit in which a cross-sectional shape is formed by a U-shaped or V-shaped slit or a recessed hole, and a plurality of short slits are arranged at predetermined intervals. In addition, the slits of the discontinuous slit row are formed in a straight line shape, a curved shape, or a bent shape in plan view.

(A) Effect According to the gas permeable film 1, the bottom 3c of the dent portion 3 can be thinned from the thickness of the film base material to substantially the limit (for example, about 2.0 μm). The range of the degree is expanded, and it can be used for a wide range of applications, and is particularly useful as a packaging material. That is, it is useful for packaging materials such as vegetables and fermented foods, and containers for fermented foods and microwave oven heating. In addition, gas permeation can be satisfactorily permeated from one direction and difficult to permeate from the opposite direction due to pressure difference or concentration difference between the inside and outside, which is effective for MA packaging, double packaging, etc. .

  Patent Document 2 listed below describes a packaging bag suitable for MA packaging. This packaging bag is a packaging bag containing a film, and this packaging bag has one or more cuts, and the ratio of length L (mm) / film thickness T (mm) per cut (L / T). ) Is 16 or more and 250 or less, the thickness T is 0.01 mm or more and 0.1 mm or less, and the total length of cuts per 100 g of fruits and vegetables is 0.08 mm or more and 20 mm or less. The length per notch is in the range of 0.1 mm to 12 mm.

  According to the specification, it is described in the specification that the packaging bag having this configuration can be produced by easy processing, and the appearance of the film does not deteriorate after processing, and the freshness of fruits and vegetables can be maintained by the MA effect.

Japanese Patent No. 5705635 Japanese Patent No. 4777658

  Since the gas-permeable film described in Patent Document 1 has the above-described configuration (A), the gas-permeable film has the excellent effect (B). Therefore, it can be used in a wide range of fields, and is particularly suitable for MA packaging. It has become a thing.

  When this permeable film is used for MA packaging, the packaging film is in a low oxygen and high carbon dioxide state, so the effect of reducing the freshness of fruits and vegetables compared to those exposed to the atmosphere, the so-called CA (Controlled Atmosphere) effect is demonstrated and the freshness can be maintained for a longer time. In addition, since this permeable film has a non-penetrating recess, entry of unnecessary materials (such as dust, dust, bacteria, etc.) into the package can be prevented and contamination of fruits and vegetables can be prevented. Water never flows out.

  As described above, this permeable film is in widespread use because it has an excellent effect in MA packaging, but recently, according to users, there is a wider range of gas permeation amount depending on the fruits and vegetables. Therefore, there is a demand for an expanded gas permeation range that conforms to these types and amounts.

Since the gas permeation amount of currently sold gas permeable films is in the range of 2000 to 5000, the desired gas permeation amount is, for example, 2500, 3000, 5000 or more, and is finely divided. ing. The unit of the gas permeation amount is the permeation amount cc per m ² for 24 hours under 1 atm, and is expressed as “cc / m ² · 24 h · at”.

  Moreover, when this gas permeable film is used for fruits and vegetables, the following thing is requested | required besides the said CA effect. For example, there is no wilting due to the transpiration of fruits and vegetables, condensation does not occur on the surface of fruits and vegetables due to temperature fluctuations, and the film does not tear or tear when handled in various ways, and the appearance is good. For example, the merchantability of the packaged product should not be reduced.

  In order to meet these demands and the like, the present inventors first examined the correspondence with a packaging bag that has already been proposed, for example, the packaging bag described in Patent Document 2 above. However, this packaging bag has many manufacturing conditions. For example, the ratio (L / T) of the length L (mm) per cut / the thickness T (mm) of the film is 16 or more and 250 or less. T should be 0.01 mm or more and 0.1 mm or less, the total length of cuts per 100 g of fruits and vegetables should be 0.08 mm or more and 20 mm or less, and the length should be 0.1 mm or more and 12 mm or less. For this reason, when trying to make a packaging bag that matches these conditions, the selection and dimension setting of the film material becomes cumbersome or complicated, the degree of freedom in designing the packaging bag is limited, and the cut length L is set to 12 mm. Then, the incision becomes long, and there are problems such as tearing, tearing, or running out of water from the part.

  In place of this, if a packaging bag without such conditions is simply provided with a cut, it is difficult to obtain the CA effect, and there are problems such as tearing, tearing, outflow of water, and poor appearance. is there.

  Fruit and vegetable film packaging has a low oxygen and high carbon dioxide concentration inside the packaging due to the breathing action of the fruits and vegetables, and if these gases are well balanced within the packaging, an excellent freshness maintaining effect can be obtained. On the other hand, if this balance is lost, the quality of fruits and vegetables may be impaired due to overhumidity damage, respiratory problems and microbial damage. Therefore, the packaging film must be designed so that such a gas balance can be taken.

  Then, the present inventors examined based on the gas-permeable film of the patent invention (the said patent document 1) which has already earned. That is, this permeable flum has a track record that has been widely used for a long time, and the gas balance is guaranteed through this track record.

  The plurality of slits constituting the slit row in this permeable film are all non-penetrating, but in order to widen the range of gas permeation amount with only the non-penetrating slit row, the number of slits is increased, It is necessary to add slit rows. If it does so, a slit and a slit row will increase, manufacture will be troublesome, and it will be inferior in appearance.

  Therefore, if you select several slits from among the multiple slits that make up the slit row, and penetrate the bottoms of the slits, and also penetrate them with fine holes, you can increase the amount of gas permeation and easily expand the range. On the other hand, if the number is reduced as much as possible, the risk of tearing and tearing can be almost avoided even when compared with the “cut” in the prior art (Patent Document 2), and the intrusion of unnecessary objects can be substantially suppressed. In addition, the production of packaging films can be done by simply expanding part of the gas permeation amount and setting it simply by changing a part of the gear shape that forms the slits without significantly modifying the conventional production equipment. I found out that it could be made.

  The present invention has been completed based on the above examination results. The present invention improves the patented invention obtained by the applicant, exhibits the effects of the patented invention, and further responds to user requests. An object of the present invention is to provide a packaging film capable of arbitrarily expanding the range of gas permeation amount. That is, an object of the present invention is to provide a packaging film capable of expanding the range of gas permeation amount according to user requirements and exhibiting an excellent MA packaging effect.

In order to achieve the above object, the packaging film according to the first aspect of the present invention is a packaging film provided with a gas permeable portion for allowing gas to permeate a plastic film substrate having a predetermined thickness.
The gas permeable portion is recessed by a predetermined depth from one surface to the other surface of the plastic film substrate, and the bottom portion bulges outward from the other surface, and the thickness gradually decreases from the recessed opening toward the bottom portion. And at least one row of slits in which a plurality of first slits having the thinnest bottom portion and a plurality of second slits having at least one through hole formed in the bottom portion of the first slit are arranged. The slit row is characterized in that the number of the first slits is larger than the number of the second slits and is mixedly arranged in the plastic film substrate.

  The packaging film of the second aspect is characterized in that in the packaging film of the first aspect, the number of the first slits is several tens of times the number of the second slits.

  The packaging film according to a third aspect is the packaging film according to the first or second aspect, wherein the gas permeable portion, the gas permeable portion is a first slit row by the first slit, and the second The second slit row by the slits is separated and disposed on the plastic film substrate.

  The packaging film according to a fourth aspect is the packaging film according to any one of the first to third aspects, wherein the second slit is formed by a plurality of through holes.

  The packaging film according to a fifth aspect is characterized in that, in the packaging film according to the first to fourth aspects, the second slit is wider than the first slit.

  According to the packaging film of the first aspect of the present invention, the effect of the patented invention obtained by the present applicant (the above-mentioned Patent Document 1) can be obtained, and the gas permeation amount requested by the user of this patented product can be obtained. A packaging film that can be enlarged can be provided.

  That is, the gas permeation part of the packaging film is composed of slit rows in which a plurality of first and second slits of different types, each of which is recessed by a predetermined depth from one surface to the other surface of the plastic film substrate, The number of the first slit is larger than the second slit of the other, and the through-hole is formed only in the second slit having a smaller number. The effect of the invention, that is, the bottom of the dent (slit) can be thinned from the thickness of the film substrate to substantially the limit (for example, about 2.0 μm), and the gas is permeated by this thinning, so it is wide. It can be used in the field.

  On the other hand, since the number of the second slits is extremely small compared to the first slits, the intrusion of unnecessary materials is suppressed or eliminated, and the through holes are not “cuts”. As a result, the fear of tearing and tearing can be avoided. This packaging film can be easily manufactured simply by exchanging the gears of the manufacturing apparatus described in Patent Document 1. The second slit may be penetrated entirely. Further, the number of first slits may be appropriately selected within a range larger than the number of second slits so that desired gas permeation characteristics can be obtained.

  Further, according to the packaging film of the second aspect, the number of the first slits is several tens of times the number of the second slits, so that the tearing due to “cutting” as in the prior art can be achieved. You can avoid the fear of tearing. The number of first slits varies depending on the desired gas permeation characteristics. However, the closer to the number of second slits, the greater the gas permeability. Therefore, the number of first slits is preferably 30. What is necessary is just to select so that a desired gas permeation characteristic may be acquired in the range of -60 times.

  Moreover, according to the packaging film of the third aspect, since the first and second slits arranged in the slit row are separated and disposed on the plastic film base material, The slit can be freely changed without being restricted by the state of the first slit, the degree of freedom of design is increased, and the range of the gas permeation amount can be further expanded.

  Further, according to the packaging film of the fourth aspect, since the second slit is formed by a plurality of through holes, the range of the gas permeation amount is not limited by the manufacturing method of the first slit. It becomes possible to expand.

  Furthermore, according to the packaging film of the fifth aspect, the second slit can be easily formed only by increasing the width of the first slit forming means.

1 shows a packaging film according to Embodiment 1 of the present invention, FIG. 1A is a plan view, FIG. 1B is an enlarged view of an IB portion of FIG. 1A, and FIG. 1C is an enlarged view of an IC portion of FIG. 2A is an enlarged sectional view taken along the line IIA-IIA in FIG. 1A, and FIG. 2B is an enlarged sectional view taken along the line IIB-IIB. 3A and 3B are diagrams for explaining the gas permeation action of one slit, FIG. 3A is a cross-sectional view of one slit, FIG. 3B is a cross-sectional view of the slit shape during gas permeation, and FIG. 3C is a gas permeation from the opposite direction. It is sectional drawing of the slit shape at the time. 4A and 4B are diagrams for explaining the gas permeation action of the other slit. FIG. 4A is a cross-sectional view of the other slit B, FIG. 4B is a cross-sectional view of the slit shape during gas permeation, and FIG. It is sectional drawing of the slit shape at the time of permeation | transmission. 5A is a schematic view of a manufacturing apparatus for manufacturing the packaging film of FIG. 1, FIG. 5B is an enlarged view of the VB portion of FIG. 5A, and FIG. 5C is an enlarged view of the VC portion of FIG. 6 shows a packaging film according to Embodiment 2 of the present invention, FIG. 6A is a plan view, FIG. 6B is an enlarged view of a VIB portion of FIG. 6A, and FIG. 6C is an enlarged view of a VIC portion of FIG. 7 shows a packaging film according to Embodiment 3 of the present invention, FIG. 7A is a plan view, and FIG. 7B is an enlarged view of a VIIB portion of FIG. 7A. 8 shows a gas permeable film of the prior art, FIG. 8A is a plan view, and FIG. 8B is a cross-sectional view taken along line VIIIB-VIIIB in FIG. 8A.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment shown below is illustrative of a packaging film for embodying the technical idea of the present invention, and is not intended to specify the present invention. It is equally applicable to those of other embodiments included in.

[Embodiment 1]
With reference to FIG. 1, the outline | summary of the film for packaging which concerns on Embodiment 1 of this invention is demonstrated. A packaging film 10 according to Embodiment 1 of the present invention is a packaging film provided with a gas permeable portion that allows gas to permeate a plastic film substrate 11 having a predetermined thickness, and the gas permeable portion is a plastic film substrate. The first part 11 is recessed by a predetermined depth from one surface to the other surface, the bottom part is bulged outward from the other surface, and the thickness is gradually reduced from the recessed opening toward the bottom part to make the bottom part the thinnest. The slit row 12L includes at least one slit row 12L in which a plurality of slits 12A and a plurality of second slits 12B each having at least one through hole formed in the bottom of the first slit are arranged. The number of first slits 12 </ b> A is larger than the number of second slits 12 </ b> B, for example, several tens of times, and is disposed in the plastic film substrate 11 in a mixed manner.

  According to this packaging film, there is provided a packaging film capable of achieving the effects of the patented invention obtained by the present applicant (the above-mentioned Patent Document 1) and capable of expanding the gas permeation amount requested by the user of this patent product. Can be provided.

  That is, the gas permeation part of the packaging film is composed of slit rows in which a plurality of first and second slits of different types, each of which is recessed by a predetermined depth from one surface to the other surface of the plastic film substrate, The number of the first slit is several tens of times larger than the second slit of the other, and through holes are formed only in the second slit having a small number. The effect of the above-mentioned patent invention can be achieved by the slit, that is, the bottom of the recess (slit) can be thinned from the thickness of the film base material to almost the limit (for example, about 2.0 μm), and gas is permeated by this thinning. Therefore, it can be used in a wide range of fields.

  On the other hand, since the number of the second slits is extremely small compared to the first slits, the intrusion of unnecessary materials is suppressed or eliminated, and the through holes are not “cuts”. The risk of tearing and tearing can be avoided. Moreover, this packaging film can be easily manufactured only by changing the gear of the manufacturing apparatus described in Patent Document 1. The number of the first slits 12A varies depending on the desired gas permeation characteristics, but the greater the number of the second slits 12B, the greater the gas permeability. Therefore, the number of the first slits 12A is greater than the number of the second slits 12B. It is sufficient that the number of the second slits 12B is several tens of times, for example, 30 to 60 times, so that a desired gas permeation characteristic can be obtained.

  Hereinafter, with reference to FIGS. 1-4, the detailed structure of the film 10 for packaging is explained in full detail. First, a film base material and a slit row will be described with reference to FIG. 1 shows a packaging film, FIG. 1A is a plan view, and FIG. 1B is an enlarged view of a portion 1B of FIG. 1A.

The film base material 11 is not limited to a specific film material, and any film base material 11 can be used. In this embodiment, an OPP (biaxially oriented polypropylene) film is preferable. The film base 11 is provided with a slit row 12L, which is a gas permeable portion. The gas permeable portion, i.e., the slit matrix 12L is configured by arranging in a line a plurality of slits 12 ₁ ~12n a predetermined interval. In the following description, the plurality of slits 12 _{1 to} 12 _n may be collectively referred to as slit 12, and these slits 12 are a mixture of two types of slits 12 A and 12 B of different types. Yes.

In FIG. 1A, one type of slit 12A is _denoted by reference numerals 12 _{2 to} 12 ₄ , 12 _{m + 1} , 12 _{m + 2} and 12 _n−1 , and the other type of slit 12B is identified by reference numerals 12 ₁ , 12 _m and 12 _n. is there. Moreover, in description of a claim, among the two types of slits 12A and 12B having different types, the former is described as a first slit, and the latter is described as a second slit.

  In this slit row 12L, the number of slits 12A and 12B is such that one slit 12A is larger than the other slit 12B, for example, several tens of times, and preferably 30 to 60 slits 12A. In other words, 30 to 60 slits 12A are arranged, and then one slit 12B is arranged so that the number of slits 12B is extremely small with respect to the slit 12A. Details of this point will be described later.

  Next, the two types of slits 12A and 12B will be described with reference to FIG. 2A is an enlarged sectional view of the IIA-IIA portion of FIG. 1A, and FIG. 2B is an enlarged sectional view of the IIB-IIB portion.

  The two types of slits 12A and 12B have substantially the same configuration. In the different configuration, one slit 12A does not penetrate the bottom and does not penetrate, whereas the slit 12B has a through hole 13 formed in the bottom. It differs in that it is installed and penetrates. As shown in FIG. 2, the structure common to both the slits 12A and 12B is such that the thickness of the body portion 12b gradually swells in a mountain shape from the upper opening groove 12a toward the bottom portion 12c, and the bottom portion 12c. Is bulged outwardly from the other surface, and the bottom 12c is thinnest so that the cross-sectional shape is substantially U-shaped.

  That is, as shown in FIG. 1B and FIG. 2, the film base 11 has a width W in the longitudinal direction and a length L and a predetermined depth in a direction perpendicular to the longitudinal direction. Although the width length, length, and depth are not particularly limited, the width length W is preferably, for example, 100 to 500 μm (0.1 mm to 0.5 mm), and the length L is preferably 1.2 to 2.6 mm. Further, the depth is about 1.2 to 2.2 times as measured from the film surface, and even with these magnifications, the depth is preferably 1.2 to 2.2 times the thickness. Furthermore, it is preferable that the thinnest wall thickness of the bottom 12c is 2 μm to 70 μm.

  Of the two slits 12A and 12B, the slit 12B is different in that a through hole 13 is formed in and penetrates the slit 12A and the bottom 12c, as shown in FIG. 2B. That is, the thickness of the body portion 112b gradually swells in a mountain shape from the upper opening 12a toward the bottom portion 12c, and the bottom portion 12c bulges outward from the other surface. The cross-sectional shape is formed in a substantially U shape so as to be thin, and one fine through hole 13 is formed in and penetrated through the bottom. The size and number of the through holes 13 are not limited, but the size is several μm to several tens of μm, the number is at least one, and one to several are formed at the bottom. These sizes and numbers are determined by the design of the gas permeation amount. The slit 12B may be penetrated entirely. Among the slits 12A and 12B, the slit 12B has a larger gas permeation amount than the slit 12A.

  Returning to FIG. 1, the arrangement of the slits 12A and 12B in the slit row 12L will be described. In the slit row 12L, two types of slits 12A and 12B of different types are respectively arranged in a row with a predetermined interval dispersed in a direction perpendicular to the longitudinal direction of the film substrate 11. Although the space | interval between adjacent slits is not specifically limited, About 1.5-3.0 mm is preferable. In this slit row 12L, among the two types of slits, the number of one slit 12A is increased and the number of the other slit 12B is decreased, so that a small number of slits 12B are dispersed between the larger number of slits 12. It is arranged.

  Below, the dispersion | distribution state of the slit 12B is illustrated. The width W and length L of each slit 12A, 12B are exemplified above. The width W is 100 to 500 μm (0.1 mm to 0.5 mm), the length L is 1.2 to 2.6 mm, and When the interval between adjacent slits is 1.5 to 3.0 mm, the slit unit 12L has a predetermined unit length, for example, 10 cm, and the slits 12B are disposed at both ends of this length, The number arranged in the slit 12A is estimated.

First, when each slit 12 has a width W of 100 μm (0.1 mm) and an interval between adjacent slits of 1.5 mm, the number is about 60.
In addition, when the width W of each slit 12 is 500 μm (0.5 mm) and the interval between the slits 12 is 1.5 mm, the number is about 30.

  From these calculations, in the slit row 12L having this length, the number of slits 12A and 12B is larger by several tens of times, for example, 30 to 60 times, in one slit 12A than in the other slit 12B. That is, one slit 12B is assigned to 30 to 60 slits 12A. In other words, after 30 to 60 slits 12A are arranged or one slit 12B is arranged in the number of slits 12A, The number of the slits 12B is extremely reduced with respect to the slits 12A.

  With this arrangement, the slits 12 provided with the through holes are distributed substantially equally without being unevenly distributed, so that the gas permeation and the like of the respective slits 12A and 12B acts in a balanced manner, and a desired gas permeation effect is obtained. In addition, each slit 12A, 12B is not limited to the said arrangement | sequence, It can change arbitrarily. Also by this, gas permeation etc. of each slit 12A, 12B acts with sufficient balance.

  Next, the gas permeation effect of the packaging film will be described with reference to FIGS. 3A and 3B are diagrams for explaining the gas permeation action of the slit 12A. FIG. 3A is a cross-sectional view of the slit 12A, FIG. 3B is a cross-sectional view of the slit shape during gas permeation, and FIG. FIG. 4 is a diagram for explaining the gas permeation action of the slit 12B, FIG. 4A is a sectional view of the slit 12B, FIG. 4B is a sectional view of the slit shape during gas permeation, and FIG. It is sectional drawing of the slit shape at the time of gas permeation from a reverse direction.

  A packaging bag of a predetermined size is produced using the packaging film 10, and fruits and vegetables are filled into the bag from the opening, and the opening is closed and sealed. The fruits and vegetables in the bag breathe, that is, consume oxygen and release carbon dioxide, so that the bag is in a state of low oxygen and high carbon dioxide, and the internal pressure changes. Due to the change in the internal pressure, gas is transmitted through the two types of slits 12A and 12B of the slit row 12L.

First, in the slit 12A, when an internal pressure is applied to the slit 12A from the direction of the arrow A in FIG. 3A, as shown in FIG. 3B, the pressure causes the body 12b and the bottom 12c to extend from the opening 12a and the bottom 12c It bulges and becomes thin. Gas passes through the thin portion 3c _1. The slit 12A has gas permeation that makes it easier to adjust the amount of permeation than the slits of the prior art and provides other effects. Specifically, when the thickness of the bottom of the slit of the prior art is substantially uniform, it cannot be made as thin as possible, and the current processing technique has a limit of about 8 μm. Since the thickness can be reduced to the limit (about 2.0 μm), the amount of permeation can be easily adjusted.

Further, when an external pressure is applied from the reverse direction (arrow A ′), as shown in FIG. 3C, the bottom 12c _{2 of the} slit is pressed in the reverse direction, but the gas permeation amount is markedly higher than that in the direction of FIG. 3B. Less. This phenomenon occurs due to an internal / external pressure difference or concentration difference, and has been confirmed by experiments. When the transmission amount from the opening side is 10, the transmission amount from the reverse direction is about 1-2. As a result, this packaging fill 10 has good gas permeability from one direction due to pressure difference or concentration difference between the inside and outside, and it is difficult to make gas permeability from the opposite direction. When used for heavy packaging, etc., there are significant effects.

The other In the slit 12B, the pressure in the direction of arrow A in FIG. 4A to the slit 12B is applied, as shown in FIG. 4B, by the pressure, body portion 12b from the opening 12a _'1 and the bottom portion 12c ' ₁ extends a little, and the gas permeates through the through-hole 13 where the thinned portion 12c' ₁ is formed at the bottom. Incidentally, the elongation of the trunk portion 12b _'1 and the bottom 12c' ₁ is trunk portion 12b ₁ and the bottom 12c ₁ is smaller than the slit 12A. Since the gas is transmitted through the through hole 13 in the slit 12B, the amount thereof is larger than that of the slit 12A. Reverse (arrow A ') when the external pressure is applied, as shown in FIG. 4C, the bottom 12c of the slit' ₂ is slightly pressed in the opposite direction the gas is transmitted.

  The two types of slits 12 </ b> A and 12 </ b> B provide the gas permeation as described above, but these shapes are not limited to the above shapes. That is, the slits 12A and 12B have a substantially U-shaped cross section, but are not limited to this, and may have other shapes, for example, a V-shaped cross section or other shapes. Moreover, although the slit row | line 12L was made into linear form, it can be made into another line, for example, a broken line form, a curved line form, etc. The slit row 12L is not limited to one row and may be two or more rows. Therefore, the amount of gas permeation of the slits and slit rows can be appropriately adjusted to a desired value by changing the shape and thickness of the bottom.

  Next, with reference to FIG. 5, the manufacturing method of the packaging film is demonstrated. 5A is a schematic view of a manufacturing apparatus for manufacturing the packaging film of FIG. 1, FIG. 5B is an enlarged view of IIIB in FIG. 5A, and FIG. 5C is an enlarged view of IIIC in FIG.

  As shown in FIG. 5A, the manufacturing apparatus 14 includes a pretreatment device 15 that pretreats the film base material 11 and a slit forming device 16 that forms two types of slits 12 </ b> A and 12 </ b> B in the film base material 11. . The pretreatment device 15 is a temperature adjustment device that treats the film substrate 11 so that the temperature exceeds the glass transition point of the substrate and is lower than the melting point.

  The temperature adjustment in the pretreatment device 15 is important for forming the slits 12 in the film substrate 11. The film substrate 11 is made of a plastic film material, that is, a polymer material. The polymer material is in a state where a crystalline portion and an amorphous portion coexist at a low temperature, and is in a glass state with a small molecular motion. ing. When heated from this state and the temperature rises, the molecular motion becomes large and becomes a rubber state, and when further heated, it enters a molten state.

  The boundary from the glass state to the rubber state is the glass transition point, and the boundary from the rubber state to the molten state is the melting point. Therefore, by heating the film substrate to a temperature exceeding the glass transition point and softening, the slit can be rolled up and the bottom can be rolled thinnest. Further, at this temperature, rolling can be performed while maintaining gas barrier properties, so that a thin slit can be formed without impairing the characteristics of the film, and a slit having no pinholes can be formed.

  The glass transition point and melting point vary depending on the material of the film substrate. When PP (polypropylene) is used for the film substrate, the glass transition point of PP is −18 ° C. and the melting point is 163 ° C. Therefore, the temperature is adjusted to 40 to 120 ° C., which is higher than normal temperature. Hereinafter, in the same manner, PET (polyethylene terephthalate) has a glass transition point of 81 ° C. and a melting point of 264 ° C. Therefore, the temperature is about 85 to 200 ° C., and LDPE (low density polyethylene) has a glass transition point. Is −125 ° C. and the melting point is 115 ° C., the temperature is adjusted to 20 to 100 ° C., which is higher than normal temperature. Moreover, in the multilayer structure film which laminated PET and LDPE mentioned later, it adjusts to the range of 85-100 degreeC of temperature.

  PP and PE already exceed the glass transition point at room temperature, but the melting point is 130 ° C., so the degree of processing is adjusted within that range. Even in the same base material, the softness of the film varies depending on the temperature in the range exceeding the glass transition point and less than the melting point. Therefore, in the next slit forming apparatus, the slit can be easily formed by raising the temperature even with light pressing.

The slit forming device 16 is a disc-shaped pressing roll 16A in which a plurality of slit forming teeth 17 are arranged at a predetermined interval on the outer periphery, and a receiving roll for sandwiching the film substrate 11 between the pressing rolls. 16B. The pressing roll 16A is formed of a metallic disk-shaped gear having a predetermined diameter, thickness, and hardness. This gear forms two types of slits 12A and 12B with a single gear, and the plurality of teeth 17 are provided with teeth that form the slits 12B. That is, this tooth is provided with slits 12 ₁ , 12 _2, and 12 n shown in FIG. 1A provided with through holes, for example, small protrusion teeth or sawtooth teeth (not shown). It has become. These teeth can be formed by simple machining of the teeth 17.

  The pressing roll 16A rotates about the shaft 16a and feeds the film base 11 in the X direction while forming the slit 12. As shown in FIG. 5B, the plurality of slit forming teeth 17 are substantially serrated teeth having a predetermined pitch p and a height h. The slit forming teeth 17 are provided with a predetermined R2 at the top end 17a and an R of R1 at the bottom 17b.

  In addition, the small protrusion-shaped tooth | gear or the sawtooth-shaped tooth | gear is provided in the top part front end 17a. The pitch p is not particularly limited, but is 2.094 mm and the height h is 2.0 mm. R2 is in the range of 0.05 to 1.0 mm, and even in this range, 0.1 to 0.2 mm is preferable. If the thickness is 0.1 mm or less, if the mechanical wear is severe, the film base material is damaged and pinholes are easily formed. If it is 1.0 mm or more, the pressing area can be widened. R1 is 0.5 mm. Note that the teeth may be continuous with a pitch of zero. In this case, the width is further reduced in order to ensure a sufficient pressing force. That is, when the number of teeth is increased, the number of teeth increases, and as a result, the unit area increases and the overall pressing force decreases. Therefore, the desired pressing force is ensured by reducing the width and reducing the area.

  The pressing roll 16A is a disc-shaped gear in the present embodiment, but may be a roll, that is, a cylindrical body or a columnar body. By making it into a roll shape, a long slit and a continuous slit can be formed. Although the gear provided with the slit forming teeth is not particularly limited, for example, it is preferable to use a gear provided with spur teeth. The flat teeth are rectangular in a plan view, have a length of 1.5 to 2.6 mm, a width of 30 to 500 μm, and 1.2 to 2.4 times the film thickness in an elevation view. Use the ones. When this flat tooth is used, if the total thickness of the film substrate is 50 μm, the thickness from the bottom of the film substrate is 60 to 120 μm up to the top of the mountain. This degree is determined by the amount of gas to be permeated. Further, depending on the shape of the slit, a gear having another shape, for example, a gear provided with helical teeth is used. For example, a slit as shown in FIG. 5B is formed using such a gear.

  Similarly to the pressing roll 6A, the receiving roll 6B receives pressure when the slit 12 is formed in the film base 11 by the pressing roll 16A while rotating around the shaft 6b, and moves the film base 11 in the X direction. Send it out. The pressure roll 16A has a hardness of 60 to 63 and is formed of a metal material having a hardness lower than that of the receiving roll 16B. The receiving roll 6B is formed of a metallic cylindrical body or cylindrical body having a predetermined diameter and hardness, and the hardness is set to 63 to 67. The pressing roll 16A is not scraped even if it is processed by, for example, 1 million m when the receiving roll 16B is pressed by the pressing roll 16A by making the hardness lower than that of the roll 6B.

  The manufacturing apparatus 14 processes the film substrate 11 to a temperature exceeding the glass transition point by the pretreatment device 15 and sends the film substrate 11 to the slit forming device 16, and the film substrate 11 that has reached a predetermined temperature by the slit forming device 16. A film is sandwiched between the pressing roll 16A and the receiving roll 16B, and a predetermined pressing force is applied to the pressing roll 16A to roll the film base 2 to form a slit (see FIG. 5C). The slit is formed by adjusting the pretreatment temperature of the substrate and the pressing force of the pressing roll according to the type and thickness of the film substrate.

  When the bottom of the slit is thinned, the gas permeability increases as the thickness is reduced, but the strength decreases. The degree is determined by adjusting at least one of the pretreatment temperature and the pressing force. For example, if the glass transition point of the film substrate is 50 ° C. and the melting point is 215 ° C., if the pretreatment temperature is 60 ° C. or 120 ° C., the latter is softer than the former, while the pressing force is lower than the former. Can be formed with a light pressing force. The degree of pressing is adjusted, for example, between 0 and 0.5 MPa, and is preferably around 0.2 MPa. In addition, 0.5 MPa is 5 kg / square centimeter.

  In this manufacturing apparatus 14, the pre-processing temperature of the film base material 11 and the pressing force of a pressing roll are adjusted according to a use, and the slit suitable for each use is formed. For example, in vegetable packaging, a single film of an OPP antifogging film having a thickness of 25 μm is used, and a slit is formed in the film from the inside of the bag. The minimum thickness of the recess (slit) is about 2.0 μm. Depending on the vegetables, the degree of pressing differs, for example, with Komatsuna, pressing at 0.2 MPa, and the shape of the portion pressed with flat teeth with a pitch of 2 mm is rectangular, 2 mm long × 200 μm wide. For a bag size of 200 mm × 320 mm, the slit row is only one horizontal row.

  According to this manufacturing apparatus 14, the range of the gas permeation amount can be arbitrarily changed simply by replacing the gear with a part of the gear shape forming the slit without changing the conventional manufacturing apparatus. Can make things.

  As described above, according to the packaging film 10, the effect of the patented invention obtained by the present applicant (the above-mentioned Patent Document 1) is exhibited, and the range of the gas permeation amount is adjusted to the user's request. The film for packaging which can be expanded and has the outstanding MA packaging effect can be provided. That is, the gas permeation part is composed of a slit row 12L in which a plurality of different types of slits 12A and 12B having a predetermined depth recessed from one surface to the other surface of the film substrate 11 are arranged, and the number thereof is Since one side is larger than the other, for example, several tens of times, and the through holes 13 are provided only in a small number of slits 12B, the effect of the above-described patented invention, that is, the depressions (slits) of the above-described patent invention is achieved by the large number of slits 12A. The bottom portion can be thinned from the thickness of the film substrate 11 to a substantially limit (for example, about 2.0 μm), and this thinning can achieve a desired gas permeability range.

  Further, the gas permeation amount is further expanded from the slit 12B provided with the through-hole, and the gas permeation amount of the slit 12A can be matched, that is, the gas permeation amount can be expanded to meet the user's request. Since the number of slits 12B is extremely small compared to other slits 12A having no through-holes, the intrusion of unnecessary materials is suppressed or almost eliminated, and the through-holes are different from “cuts”. There is no danger of tearing, tearing, or water falling outside like a “cut”. Moreover, what can change the range of gas permeation | transmission amount arbitrarily can be produced simply by replacing | exchanging with the gear which changed a part of gear shape which forms a slit, without remodeling the conventional manufacturing apparatus.

  With reference to FIG. 6, the packaging film which concerns on Embodiment 2 of this invention is demonstrated. 6 shows a packaging film according to Embodiment 2 of the present invention, FIG. 6A is a plan view, FIG. 6B is an enlarged view of a VIB portion of FIG. 6A, and FIG. 6C is an enlarged view of a VIC portion of FIG. .

As shown in FIG. 6A, the packaging film 10 </ b> A according to the second embodiment is obtained by providing the film base 11 with two slit rows, that is, the first slit row 12 </ b> L ₁ and the second slit row 12 </ _b > L _2. It is. That is, one of the two types of slits 12A and 12B mixed in the slit row 12L of the packaging film 10 of Embodiment 1 is separated from the slit row 12L, and this is used as the slit 12C. it is obtained by a slit rows 12L ₂ by disposing the slit 12C in the film substrate 11 in a row.

  According to this packaging film 10A, the slit 12A has the same effect as the slit 12A of the first embodiment, and the other slit 12C also has the same effect as the slit 1B. The slit 12C is a second slit. On the other hand, the slit 12C can be formed into an arbitrary shape by being different from the slit 12B.

  The slit 12C shown in FIG. 6 is formed by a through hole group composed of a plurality of fine holes. According to this, in the slit row 12L of the packaging film 10, the slits 12A and 12B had to have substantially the same shape, but by separation, the slit row 12L can be changed to an arbitrary one without being restricted by the manufacturing method of the slit 12A, This facilitates expansion of the range of gas permeation. The packaging film 10 </ b> A can be manufactured using the manufacturing apparatus 14. In addition, the slit 12C may penetrate the whole.

  With reference to FIG. 7, the packaging film which concerns on Embodiment 3 of this invention is demonstrated. 7 shows a packaging film according to Embodiment 3 of the present invention, FIG. 7A is a plan view, and FIG. 7B is an enlarged view of a VllB portion of FIG. 7A.

In the packaging film 10B according to the third embodiment, two slits 12C of the packaging film 10A of the second embodiment are crossed to form slits 12D. As shown in FIG. two rows, i.e. is provided with a first slit rows 12L ₁ and second slit rows 12L _3. Note that the slit 12D is not limited to the one provided with the through-hole as in the slit 12C, but may be of another shape, or may be the whole penetrating through.

  According to this packaging film 10B, since the second slit 12D is formed by at least two slits, it can be made different from the first slit 12A to further expand the range of the gas permeation amount. .

10, 10A, 10B Packaging film 11 Plastic film substrate 12 Slit 12A Slit (first slit)
12B, 12C, 12D Slit (second slit)
12a opening 12b barrel 12c bottom _{12L, 12L 1, 12L 2,} 12L 3 slit matrix 13, 13A, 13B through holes 14 manufacturing apparatus 15 pretreatment device 16 slits forming apparatus 17 slits formed teeth

Claims (5)

A packaging film provided with a gas permeable portion that allows gas to permeate a plastic film substrate of a predetermined thickness,
The gas permeable portion is recessed by a predetermined depth from one surface to the other surface of the plastic film substrate, and the bottom portion bulges outward from the other surface, and the thickness gradually decreases from the recessed opening toward the bottom portion. And at least one row of slits in which a plurality of first slits having the thinnest bottom portion and a plurality of second slits having at least one through hole formed in the bottom portion of the first slit are arranged. Consist of columns
The slit film is a packaging film characterized in that the number of the first slits is larger than the number of the second slits and is mixed and disposed in the plastic film substrate.   The packaging film according to claim 1, wherein the number of the first slits is several tens of times the number of the second slits.   The gas permeation part is disposed on the plastic film substrate by separating a first slit row by the first slit and a second slit row by the second slit. The packaging film according to claim 1 or 2.   The packaging film according to claim 1, wherein the second slit is formed of a plurality of through holes.   The packaging film according to claim 1, wherein the second slit is wider than the first slit.

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