JP2020070022A - Method for manufacturing perforated resin film used for garden stuff freshness keeping container, method for manufacturing garden stuff freshness keeping container, and system for manufacturing perforated resin film used for garden stuff freshness keeping container - Google Patents

Abstract

To provide a method capable of stably providing a bore in a film in a method for manufacturing a perforated resin film used for a garden stuff freshness keeping packaging bag (in particular, a manufacturing method including a printing process using inks and a boring process by lasers).SOLUTION: A method for manufacturing a perforated resin film includes a printing process for printing inks including an organic solvent in at least part of a resin film, and a boring process for providing a bore by irradiating the resin film with laser light from a laser light source. Under an environment where an organic solvent concentration Cin an air near a portion where the printing process is performed is controlled to be different from an organic solvent concentration Cin the air near a portion where the boring process is performed. Also a system performing such the method is provided.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to a method for producing a perforated resin film used for a container for keeping freshness of fruits and vegetables, a method for manufacturing a container for keeping freshness of fruits and vegetables, and a system for manufacturing a resin film for perforation used for a container for keeping freshness of fruits and vegetables.

Vegetables, fruits and other fruits and vegetables continue to have a respiratory effect even after being harvested. Therefore, during storage, distribution or preservation after harvesting, energy is consumed by the respiration of the fruits and vegetables themselves, causing deterioration of freshness.
Therefore, studies have been conducted so far to suppress the deterioration of freshness of fruits and vegetables by wrapping the fruits and vegetables with an appropriate packaging material (for example, a synthetic resin film).

As an example, Patent Document 1 describes a moisture permeable / breathable packaging material in which a polyethylene terephthalate (PET) non-woven fabric having a basis weight of 30 to 70 g / m ² , a printing layer, and a polyolefin resin layer are sequentially laminated. Has been done. The characteristic of this packaging material is that a plurality of holes penetrating the polyolefin resin layer are formed in predetermined areas of the polyolefin resin layer.

  As another example, in the packaging bag for fruits and vegetables described in Patent Document 2, one or more openings having a total opening area of 0.02 to 3.5% with respect to the total film surface area of the bag are provided. It is specified that

JP, 2006-231723, A JP-A-63-119647

When a packaging bag for maintaining freshness of fruits and vegetables is formed by using a resin film, holes (typically through holes) may be provided in the resin film in order to adjust air permeability. That is, fruits and vegetables may be packaged using a perforated resin film (or a packaging bag made of the film).
Particularly, recently, in consideration of the respiration of fruits and vegetables, it is becoming widespread to wrap fruits and vegetables in a packaging bag provided with holes having an appropriate number, density and diameter.
Various methods such as laser and hot needle may be used to form the holes in the resin film. Among these, the method of perforating a resin film with a laser is advantageous in terms of productivity, maintainability of an apparatus, etc., since the resin film is not directly touched.

  In addition, characters and figures are often printed on the freshness-keeping packaging bag for fruits and vegetables (or the resin film constituting the bag). For example, the item, number, weight, producer, seller, trademark, logo mark, bar code, two-dimensional code, etc. of vegetables and fruits to be packaged are often printed with ink.

The present inventor tried to manufacture a perforated resin film used for a container for freshness of fruits and vegetables by performing both printing with an ink and perforation with a laser on the resin film. For some reason, in some cases, the intended perforation could not be performed in the attempt. Specifically, the present inventor has found that the following phenomenon occurs.
(1) When the resin film is not perforated and only the laser film is perforated, the holes can be provided without any particular problem.
(2) However, when both the printing process using the ink and the perforating process with the laser are performed in a short time, the conditions such as the laser intensity and the irradiation time are the same as those in (1). In some cases, the same hole as in (1) cannot be stably provided. That is, when both the printing using the ink and the perforation with the laser are performed in a short time, the intended perforation may not be stably performed.

  The present invention has been made in view of such circumstances. One of the objects of the present invention is to stabilize a film in a method for producing a perforated resin film used for a bag for keeping freshness of fruits and vegetables (particularly, a production method including a printing step using ink and a perforation step by laser). It is to provide a method by which holes can be provided.

  The present inventor examined the cause of the problem (2) from various angles. As a result of the study, it was found that the concentration of the organic solvent (the organic solvent is mainly volatilized from the ink) at the place where the printing process or the perforation process is performed seems to be related to stable perforation. Based on this finding, the inventor has completed the inventions provided below.

According to the invention,
A method for producing a perforated resin film used for a container for maintaining freshness of fruits and vegetables,
A printing step of printing an ink containing an organic solvent on at least a part of the resin film, and a perforation step of forming holes by irradiating the resin film with a laser beam from a laser light source,
In an environment controlled such that the organic solvent concentration C _{1 in} the air near the place where the printing process is performed and the organic solvent concentration C ₂ in the air near the place where the perforation process is performed are different, There is provided a method for manufacturing a perforated resin film, which comprises performing the printing step and the perforating step.

Further, according to the present invention,
Provided is a method for producing a container for freshness of fruits and vegetables, which includes a container making step of making a container using the resin film having a hole produced by the method for producing a resin film having a hole.

Further, according to the present invention,
A system for producing a perforated resin film used for a container for freshness of fruits and vegetables,
A printing device section that prints an ink containing an organic solvent on at least a part of the resin film,
A perforating device section which irradiates a laser beam from the laser light source to the resin film to provide a hole,
A system is provided, which comprises control means for controlling the organic solvent concentration C _{1 in the} vicinity of the printing unit and the organic solvent concentration C _{2 in} the air in the vicinity of the punching unit to be different.

  ADVANTAGE OF THE INVENTION According to this invention, in the manufacturing method of a perforated resin film used for a freshness-keeping packaging bag for fruits and vegetables (particularly, the manufacturing method including a printing process using ink and a perforation process by laser), the film is stably perforated. Is provided.

It is a figure for demonstrating the manufacturing method of the perforated resin film used for a freshness container for fruits and vegetables. It is a figure for demonstrating the aspect of a printing device part etc. (left half part in FIG. 1) when a printing process is performed by a gravure printing method. It is a figure for demonstrating the aspect of a printing device part etc. (left half part in FIG. 1) when a printing process is performed by an offset printing method. It is the figure which showed more concretely an example of the laser irradiation apparatus 13 and its periphery in the punching apparatus part of FIG. It is the figure which represented typically an example of the support roll 14 in FIG. It is a figure for explaining an example of control means which controls solvent concentration. It is a figure for explaining an example of control means which controls solvent concentration. It is a figure for explaining an example of control means which controls solvent concentration. It is a figure for explaining an example of control means which controls solvent concentration. It is a figure for explaining an example of control means which controls solvent concentration.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In all the drawings, the same constituents will be given the same reference numerals, and the description thereof will not be repeated.
In order to avoid complication, (i) when there are a plurality of the same constituent elements in the same drawing, only one of them is given a reference numeral and all are not given a reference numeral, or (ii) especially After 2, the same components as those in FIG. 1 may not be denoted by the reference numerals.
All drawings are for illustration purposes only. The shapes and dimensional ratios of the respective members in the drawings do not necessarily correspond to actual articles.

In this specification, the term “substantially” indicates that it includes a range in which manufacturing tolerances, assembly variations, and the like are taken into consideration, unless otherwise specified.
In the present specification, the notation “a to b” in the description of the numerical range indicates a or more and b or less, unless otherwise specified. For example, "1 to 5 mass%" means "1 mass% or more and 5 mass% or less".
The expression "(meth) acrylic" in the present specification represents a concept including both acrylic and methacrylic. The same applies to similar notations such as “(meth) acrylate”.

<Method of manufacturing perforated resin film>
FIG. 1 is a diagram for explaining a method of manufacturing a perforated resin film used for a freshness container for fruits and vegetables.
FIG. 1 includes a printing device unit and a punching device unit.
In FIG. 1, the resin film 1 is unwound from an unwinding roll 11, travels in the direction from left to right in the figure, and is finally wound up by a winding roll 12.
Ink from the organic solvent is applied to at least one surface of the resin film 1 in the printing device section between the time the resin film 1 is unwound and the time it is wound up. As a result, the ink portion 2 is formed. That is, a printing step of printing an ink containing an organic solvent on at least a part of the resin film is performed.
In addition, the laser irradiation device 13 irradiates the resin film 1 with laser light in the punching device section between the time the resin film 1 is unwound and the time it is wound up. As a result, holes are provided in the resin film 1 (holes are not shown in FIG. 1). That is, a perforation step of irradiating the resin film 1 with laser light from the laser irradiation device 13 to form holes is performed. In FIG. 1, the support roll 14 exists on the side of the resin film 1 opposite to the laser irradiation device 13.

In FIG. 1, the concentration of the organic solvent in the air in the vicinity of the portion where the printing process is performed (the portion indicated by reference symbol α) is C _1, and in the air in the vicinity of the portion where the perforation process is performed (the portion indicated by the reference symbol β) When the concentration of the organic solvent is C ₂ , C ₁ and C ₂ are controlled so as to be different by an appropriate control means (not shown in FIG. 1). The magnitude relationship between C ₁ and C ₂ is preferably C ₁ > C ₂ .

The control means for controlling so that C ₁ and C ₂ are different is not particularly limited. As a result of the presence of some artificial structure, mechanism or device, C ₁ and C ₂ need to be continuously different during the printing and punching steps.
A specific example of the mode of the control means will be described later.
It should be noted that a mode in which C ₁ and C ₂ are “naturally” different from each other without any artificial mechanism or device is not included in the present invention. For example, embodiments in which C ₁ and C ₂ are temporarily different as a result of natural gas convection or air conditioning normally performed in a printing plant are not included in the present invention.

As described above, the reason why the holes can be stably provided in the film by performing the printing process and the perforating process under the control that C ₁ and C ₂ are different from each other is explained as follows. can do. The following description does not limit the scope of the present invention.

Through various studies, the present inventor seems to be unable to perform stable perforation because the organic solvent that volatilizes or scatters from the ink and drifts in the air causes laser light to be scattered / absorbed. I found out that.
Based on this finding, the present inventor has performed the printing step and the punching step in a controlled environment in which C ₁ and C ₂ are different (preferably C ₁ > C ₂ ). As a result, holes can be stably provided in the film (resin film 1).

In addition, as described above, the magnitude relationship between C ₁ and C ₂ is preferably C ₁ > C ₂ . However, the case where C ₁ <C ₂ is not necessarily excluded. For example, even though a C 1 _{<C 2,} (smaller variation of C ₂ is sufficiently) C ₂ is a constant if it is controlled within the numerical ranges, believed to be the stable drilling.

C ₁ and C ₂ can be measured using, for example, a commercially available measuring instrument. For example, a device used for measuring the work environment based on the Industrial Safety and Health Act can be used.
More specifically, C ₁ and C ₂ can be measured using a detector tube type measuring instrument. That is, C ₁ and C ₂ can be measured using a detector tube suitable for the type of the organic solvent that volatilizes or scatters from the ink containing the organic solvent.
Measuring instruments using a detector tube system are available from, for example, Gastec Co., Ltd., Komei Rikagaku Kogyo Co., Ltd., Idec Co.
Of course, the measuring method is not limited to the detector tube method. The value of C ₁ and C _2, measured at least C ₁ and C ₂ of the magnitude relationship of the degree to which apparent accuracy if possible, may be measured by any measurement method.

The place where C ₁ is measured is not particularly limited as long as it is in the vicinity of the place where the printing process is performed, but the concentration of the organic solvent at the place as close as possible to the place where the ink containing the organic solvent is applied to the resin film 1 in the printing device section It is preferably measured.

For example, C ₁ is the organic solvent concentration at an arbitrary position within 1 m from the position where the ink containing the organic solvent is applied to the resin film 1 in the printing device section, more specifically, at a position of 50 cm, and C _{1 is} Can be adopted as
The "location where the ink containing the organic solvent is applied to the resin film 1 in the printing device section" means, for example, when the printing process is performed by a gravure printing method as shown in FIG. It can be a place where 23 contacts the resin film 1. Further, when the printing process is an offset printing method as shown in FIG. 3 described later, it can be a place where the blanket cylinder 34 comes into contact with the resin film 1.

The place where C ₂ is measured is not particularly limited as long as it is near the place where the perforation process is performed, but it is preferable to measure the organic solvent concentration at a place as close as possible to the laser irradiation device 13.
For example, C ₂ is an arbitrary location within 1 m from the line connecting the tip of the laser irradiation device 13 (where the laser light is emitted) and the point where the laser light hits the resin film 1, more specifically, 50 cm. The local organic solvent concentration can be taken as C ₂ .

As a reminder, if it is obvious that C ₁ and C ₂ are sufficiently different as a result of the control means described later, (if C ₁ and C ₂ are different or C ₂ is C It is not necessary to specify the place for measuring C ₁ and the place for measuring C ₂ so strictly as long as it is confirmed to be sufficiently smaller than ₁ .

From the viewpoint of more stable perforation, C ₂ is preferably 5 vol% or less, more preferably 0 to 5 vol%, further preferably 0 to 3 vol%, and 0 to 0.5 vol. % Is particularly preferable.
Reducing C ₂ is preferable in terms of improving the working environment and safety (reducing the risk of ignition, explosion, etc.) as well as enabling stable drilling.

The value of C ₁ is not particularly limited, but when C ₁ > C ₂ , the value of C ₂ / C ₁ is preferably 0 to 0.5, and 0 to 0.1. More preferably, it is more preferably 0 to 0.01.
It is considered that when the value of C ₂ / C ₁ is 0.5 or less, more stable drilling can be performed.

The value of C ₁ itself is preferably ₁ vol% or less. The value of C ₁ is equal to or less than 1 vol% (C ₁ is not so large) is preferable from the viewpoint of good working environment, reduced risk (reduction potential of fire or explosion).

In FIG. 1, the punching process is performed after the printing process. However, this order is not particularly limited. A printing process may be performed after the punching process.
However, it is preferable to perform the perforation step after the printing step from the viewpoint that the holes are not covered with ink.

In FIG. 1, from the viewpoint of productivity, it is preferable that the printing step and the perforation step be continuously performed while the resin film 1 is running. In other words, it is preferable that the resin film 1 is continuously unwound and wound, while the printing step and the perforating step are performed during that period.
Of course, as long as the perforation is appropriately performed, even if the resin film is temporarily stopped between the printing process and the perforating process, there is no particular problem other than productivity.
The traveling speed of the resin film 1 may be appropriately set within a range of, for example, 0.001 to 50 m / s, preferably 0.02 to 20 m / s. Higher running speed is preferable in terms of productivity.
The traveling speed may be appropriately changed depending on the number (density) of the holes provided in the resin film 1, the pulse frequency of the laser light emitted from the laser irradiation device 13, and the like.

  The time between the printing step and the punching step is, for example, 0.1 to 600 seconds, preferably 0.2 to 60 seconds. The shorter this time is, the more preferable from the viewpoint of productivity.

  The description relating to FIG. 1 will be continued.

(Printer unit / Printing process)
Although the specific mechanism of the printing device unit is not shown in FIG. 1, the printing device unit may have any form as long as the ink unit 2 can be provided on the resin film 1.
In other words, the printing process can be performed by any method. For example, any printing method such as a gravure printing method, an offset printing method, a flexographic printing method, an inkjet printing method, a screen printing method, and a pad printing method can be used.

FIG. 2 schematically shows an aspect of a printing device unit and the like (the left half portion in FIG. 1) when the printing process is performed by the gravure printing method.
In FIG. 2, a part of the gravure roll 23 is in contact with the ink composition 2A contained in the ink pan 22.
A concave portion is provided on the surface of the gravure roll 23 (not shown in FIG. 2). Ink composition 2A collects in this recess. The concave portion is typically formed by a method of engraving a copper plating applied on the gravure roll 23 with a diamond needle or a method of laser exposure, development and corrosion.
The gravure roll 23 is usually accompanied by a doctor blade for removing the excess ink composition 2A (not shown in FIG. 2).

In FIG. 2, the resin film 1 unwound from the unwinding roll 11 is turned by the guide roll 21. After that, the resin film 1 passes between the gravure roll 23 and the impression cylinder 24 installed so as to face the gravure roll 23. During this passage, the ink composition 2A accumulated in the concave portion on the surface of the gravure roll 23 is transferred to the resin film 1. Then, the ink unit 2 is provided.
The resin film 1 provided with the ink portion 2 is conveyed while being turned by the guide roll 21, and heads toward the punching device portion.

  Various conditions for gravure printing may be appropriately set based on common technical knowledge in the gravure printing field.

FIG. 3 schematically shows an aspect of a printing device unit and the like (the left half portion in FIG. 1) when the printing process is performed by the offset printing method.
In FIG. 3, a plate cylinder 33, an ink supply device 32 for supplying an ink composition to the plate cylinder 33, a water supply device 31 for supplying dampening water (not shown) to the surface of the plate cylinder 33, and a plate cylinder 33 are provided. The blanket cylinder 34 is disposed so as to face each other, and the ink composition adhered to the plate cylinder 33 is pressed by the plate cylinder 33 to be transferred to the surface, and the impression cylinder 35 disposed so as to face the blanket cylinder 34. There is.
The plate cylinder 33, the blanket cylinder 34, and the impression cylinder 35 are adapted to rotate in the directions indicated by arrows in the figure.

In one aspect, the plate cylinder 33 has a lipophilic part of its surface and a hydrophilic part of the other surface so that the ink composition selectively adheres to the lipophilic part. .. A known PS plate (Pre-Sensitized Plate) technique can be applied as a means for providing the lipophilic / hydrophilic region.
The surface of the blanket cylinder 34 is typically made of a rubber material so that the ink composition attached to the plate cylinder 33 is transferred.

  The resin film 1 is sandwiched between the impression cylinder 35 and the blanket cylinder 34. The sandwiched resin film 1 is conveyed from the left side to the right side in FIG. Then, the ink composition transferred to the surface of the blanket cylinder 34 is transferred to the surface of the resin film 1. The ink portion 2 is provided on the surface of the resin film 1 by this series of flows.

  Various conditions regarding offset printing may be appropriately set based on common technical knowledge in the field of offset printing.

(Resin film 1)
The resin forming the resin film 1 is not particularly limited as long as it can be used for packaging fruits and vegetables. It can be appropriately selected from the viewpoints of the type of fruits and vegetables to be packaged, processability (for example, ease of bag making), cost, and the like.

Specific examples of the resin include polyethylene or ethylene copolymer, polypropylene, polyvinyl chloride, polystyrene, (meth) acrylic resin, polyester resin such as polyethylene terephthalate and polylactic acid, and polyamide resin such as 6 nylon. These may be homopolymers or copolymers containing two or more types of structural units.
The resin film 1 may include two or more kinds of resins.

  Specific examples of polyethylene or ethylene copolymer include ethylene / vinyl alcohol copolymer, high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, metallocene-linear low density polyethylene, ethylene- Examples thereof include vinyl acetate copolymers, ethylene- (meth) acrylic acid copolymers, ethylene-propylene copolymers, ethylene-α-olefin copolymers, and other ionomers.

  The resin film 1 may have a single layer structure or a multilayer structure of two or more layers.

  The manufacturing method (film forming method) of the resin film 1 is not particularly limited. Known methods such as extrusion, inflation, and calendering can be applied. Even when the resin film 1 has a multi-layer structure, known methods such as coextrusion (extrusion using a multi-die) and various laminating methods can be appropriately applied.

When manufacturing the resin film 1, additives such as an antifogging agent may be kneaded or applied as necessary. Further, two or more kinds of resins may be blended. Further, during film formation, stretching treatment, annealing treatment or the like may be performed.
The surface of the resin film 1 may be provided with an additional layer such as a sealant layer, or may be coated or surface-treated to impart some function.
The resin film 1 may be transparent or opaque. It is preferable that the contents are transparent in terms of visibility.

As one aspect, it is preferable that the contact angles of water on the front surface and the back surface of the resin film 1 (which is not printed or perforated) are different. By using such a resin film 1, it is considered that, for example, the effect of improving the adhesion and scratch resistance of the ink portion 2 to the resin film 1 can be obtained.
Specifically, the two principal surfaces of the resin film 1 on which printing and perforation are not performed are the first surface and the second surface, the contact angle of water on the first surface is θ ₁ , and the contact angle of water on the second surface. when was the theta _2, the value of theta _{1 /} theta ₂ is preferably greater than 1 and less than 9. Then, the printing step is preferably performed by applying an ink containing an organic solvent to the first surface of the resin film 1.

Further, as an additional merit, when the resin film 1 having a value of θ ₁ / θ ₂ of more than 1 and less than 9 is used, it is considered that there is an effect of reducing dew condensation and mold when the fruits and vegetables are packaged.
Specifically, using the resin film 1 having a value of θ ₁ / θ ₂ of more than 1 and less than 9 as a material, the second surface having a large contact angle of water is manufactured so that the inner surface is the freshness preservation of fruits and vegetables. Due to the size of the contact angle of water on the inner surface side of the container, dew condensation is unlikely to adhere. If the condensation does not easily adhere, the growth of the mold tends to be suppressed.

The value of θ ₁ / θ ₂ is preferably more than 1 and 8 or less, and more preferably 1.3 or more and 7 or less. When the value of θ ₁ / θ ₂ is within the above numerical range, it is possible to improve the balance between the ink printability on the outer surface and the dew condensation prevention property on the inner surface when the resin film 1 is used as a packaging container. it can.

The value of θ ₁ is preferably 30 to 100 °, more preferably 40 to 90 °, and further preferably 50 to 90 ° from the viewpoint of improving printability.
The value of θ ₂ is preferably 3 to 60 °, more preferably 5 to 55 °, and further preferably 10 to 50 ° from the viewpoint of highly suppressing the generation of dew condensation and mold.

As a method of adjusting the values of θ ₁ and θ ₂ (and the value of θ ₁ / θ ₂ ), for example, there is a method of performing an appropriate surface treatment (for example, corona treatment) on at least one side of the resin film 1.
The values of θ ₁ and θ ₂ (and the value of θ ₁ / θ ₂ ) may be adjusted by forming the resin film 1 into a multi-layered structure. For example, one surface can be made of a resin material containing an ethylene / vinyl alcohol copolymer, and the other surface can be made of a resin material containing a polyamide resin. By doing so, when the resin film 1 is used as a packaging container, both the printability of the outer surface and the dew condensation prevention property on the inner surface are compatible, and the conditions suitable for storing fruits and vegetables are provided in the inner space of the packaging container. It can be stably constructed.
Further, a method in which the resin film 1 has a multi-layered structure and one surface layer contains an antifogging agent can be used. Specific examples of the antifogging agent include glycerin laurate, diglycerin laurate, decaglycerin laurate, glycerin monostearate and sorbitan stearate.

The smaller the contact angle of water, the easier the surface of the object is to get wet with water, and the higher the contact angle of water, the more easily the surface of the object repels water.
As a method for measuring the contact angle of water, for example, a commercially available contact angle meter such as DROPMASTER-501 manufactured by Kyowa Interface Science Co., Ltd. is used, and 2 μL of purified water is dropped on the surface to be measured and water contact is made 7 seconds later. A method of measuring the corner by the droplet method can be used.

The thickness of the resin film 1 is, for example, 3 to 500 μm, preferably 10 to 200 μm.
When the thickness of the resin film 1 is 10 μm or more, it becomes easy to obtain sufficient strength.
In addition, when the thickness of the resin film 1 is 200 μm or less, reduction of manufacturing cost and improvement of handling property can be expected.

(Ink containing organic solvent / ink part 2)
The ink printed on the surface of the resin film 1 in the printing step is not particularly limited as long as it contains an organic solvent. Any ink can be used as long as desired characters or figures can be printed. For example, among the commercially available gravure inks and offset inks, those suitable for resin film printing can be appropriately selected.
The ink typically contains, in addition to an organic solvent, a colorant such as a pigment, a resin, oils and fats (drying oil, etc.), various additives (anti-friction material, dryer, viscosity modifier, rheology modifier), etc. be able to.

The organic solvent contained in the ink may be, for example, at least one solvent selected from the group consisting of alcohol solvents, ketone solvents and ester solvents.
Specific examples thereof include ester solvents such as ethyl acetate and butyl acetate, alcohol solvents such as isopropyl alcohol and n-butanol, and ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone. Of course, the organic solvent is not limited to these. Further, the ink may contain two or more kinds of organic solvents (volatile organic solvents).

  When the ink contains a plurality of types of organic solvents, the concentration of at least one type of organic solvent in the air near the place where the printing process is performed and the concentration in the air near the place where the perforation process is performed Are preferably different. More preferably, for all kinds of organic solvents contained in the ink, the concentration in the air near the place where the printing process is performed and the concentration in the air near the place where the perforation process are different are different. preferable.

  The ink unit 2 can represent arbitrary characters and figures. For example, the inking unit 2 may be an item of fruit and vegetables to be packaged, the number, weight, producer, seller, trademark, logo mark, bar code, two-dimensional code, or the like.

(Punching device section: laser irradiation device 13, support roll 14, etc.)
The punching device section includes at least a laser irradiation device 13.
The type and output of the laser light source are not particularly limited so that the resin film 1 can be perforated. For example, a ruby laser, neodymium YAG laser, neodymium glass laser, carbon dioxide laser, etc. can be mentioned. Among these, the carbon dioxide gas laser is preferable because it has high energy efficiency, is easy to obtain a high output, and is advantageous in forming a hole by heating and melting the resin film.
The laser irradiation device 13 preferably includes a pulse laser. The pitch of the holes can be adjusted by appropriately adjusting the traveling speed of the resin film 1 and the pulse frequency of the pulse laser.

More specifically, the punching device section can be configured as shown in FIG.
FIG. 4 is a diagram more specifically showing an example of the laser irradiation device 13 and its periphery in the punching device portion of FIG. 1 (the support roll 14 is not shown in FIG. 4).
In FIG. 4, the resin film 1 is running below the nozzle tip 45 of the laser irradiation device 13.

In FIG. 4, the pulse laser 40 passes through the light guide path 41 and is focused by the emission optical section (lens) 42. Therefore, the laser beam becomes a conical beam 43 and is irradiated onto the resin film 1 from the nozzle tip 45.
At this time, the inner diameter of the nozzle tip 45 is made larger than the beam diameter of the passing pulse laser 40. Further, it is preferable that the focal position of the pulse laser 40 focused by the emitting optical unit (lens) 42 is a position slightly outside the film from the surface of the resin film 1 opposite to the laser incident surface. By making the focal position intentionally out of the film, it is easy to obtain a hole suitable for keeping the freshness of fruits and vegetables.

  By irradiating with the conical beam 43, the portion of the resin film 1 where the beam hits is melted, decomposed, volatilized, or the like. Thereby, the hole 5 is formed. In addition, usually, at this time, a “hump” is formed around the hole due to melting of the resin film 1 or the like (the “hump” is not clearly shown in FIG. 4).

The pitch of the holes 5 drilled in the resin film 1 can be adjusted by the traveling speed of the resin film 1 and the pulse frequency of the pulse laser 40.
Normally, 20 to 1000 holes 5 can be formed in one second by one laser irradiation device. High productivity can also be achieved by increasing the running speed of the resin film 1.

The hole 5 formed in the resin film 1 has substantially the same shape as the conical beam 43 passing through the resin film 1. In the present embodiment, by appropriately controlling so that C ₁ and C ₂ are different, it is possible to continuously provide holes of a substantially constant shape.
The conical trapezoidal hole can be made closer to a cylindrical shape by increasing the focal length of the emission optical unit (lens) 42.
By appropriately moving the laser irradiation device 13 during laser irradiation, the shape of the hole can be made substantially elliptic instead of being substantially circular.

  A compressed gas introduction path 44 can be provided near the nozzle tip 45 of the light guide path 41 in the laser irradiation device 13. By doing so, compressed gas can be blown to the resin film 1 along the laser beam during laser irradiation.

  The blowing speed of the compressed gas is preferably moderately high. This is to prevent the decomposed product generated by perforation from entering from the nozzle tip 45 and contaminating the emission optical unit (lens) 42. As an example, the wind speed at the nozzle tip 45 is preferably set to 2 to 10 m / s, more preferably 3 to 6 m / s.

  The compressed gas that can be used is not particularly limited. For example, in addition to compressed air, an inert gas such as nitrogen gas or carbon dioxide gas can be used. Compressed air has no handling risk and is advantageous in terms of cost. The inert gas can suppress the oxidation of the decomposition products of the resin film 1 and reduce soot, charring, black matter, and the like.

FIG. 5 schematically shows an example of the support roll 14 in FIG.
The support roll 14 is preferably provided with, for example, a groove 46 corresponding to the laser irradiation position. Thereby, the decomposed material of the resin film 1 can be volatilized or removed from the side opposite to the laser incident surface.
The support roll 14 in FIG. 5 has five grooves 46. When five laser irradiation devices 13 are used together with such a support roll 14, the resin film 1 can be provided with five rows of holes.

  According to the drilling method described here, the diameter of the hole and the position of the hole can be highly controlled. The selection of film materials, laser processing conditions, etc. will be described in the examples described later.

The diameter and density of the holes may be appropriately adjusted according to desired air permeability and the like.
The diameter of the holes can be, for example, 1 to 2000 μm, preferably 10 to 1000 μm, and more preferably 20 to 500 μm. When the final container for freshness of fruits and vegetables has a plurality of holes, it is preferable that the diameters of all the holes are within these numerical ranges.
The density of the holes can be, for example, 0.1 to 100,000 holes / m ² , preferably 1 to 10,000 holes / m ² , and more preferably 5 to 5000 holes / m ² .

(Control means for organic solvent concentration)
As described above, in this embodiment, proper control is performed so that C ₁ and C ₂ are different from each other, so that holes having a substantially constant shape can be continuously provided. Hereinafter, some specific modes of the control means will be described. The control means is not limited to the following.

・ Exhaust (Fig. 6)
As an example, as shown in FIG. 6, an exhaust device 6 that exhausts at least a part of the ink or the organic solvent volatilized from the ink unit 2 is provided near the printing unit. This makes it possible to control so that C ₁ and C ₂ are different.

・ Ventilation (Figs. 7 and 8)
As another example, as shown in FIG. 7, a blowing device 7 is installed near the printing device unit, and air is blown from around the printing device unit to ventilate air near the place where the printing process is performed. This makes it possible to control so that C ₁ and C ₂ are different.
Alternatively, as shown in FIG. 8, a blower 7 is installed near the laser irradiation device 13, and air is blown from the vicinity of the laser irradiation device 13 to the vicinity of the laser irradiation device 13 to ventilate the air in the vicinity of the location where the perforation step is performed. Thereby, C ₁ and C ₂ may be controlled so as to be different from each other.

・ Printing and punching in another section (Fig. 9)
As another example, as shown in FIG. 9, the periphery of the printing device unit and the periphery of the punching device unit are physically separated as first partition 8A and second partition 8B, respectively.
Thereby, movement of air is restricted between the first section 8A and the second section 8B (for opening and closing the resin film 1 that is vacant on the side surfaces of the first section 8A and the second section 8B). The air is prevented from moving except through a small gap), and C ₁ and C ₂ are controlled to be different.
More specifically, the first compartment 8A and the second compartment 8B can be separate rooms. Alternatively, when the printing apparatus section and the punching apparatus section are provided in one room, the first section 8A and the second section 8B may be provided by an appropriate cover, enclosure, partition or the like.
It is preferable that the first section 8A and the second section 8B be separately air-conditioned.

・ Protection around the laser irradiation device 13 (Fig. 10)
As another example, as shown in FIG. 10, in order to limit contact of air containing the organic solvent evaporated from the ink with the laser light source around the laser irradiation device 13 (that is, the laser light source or its vicinity). A member (cover 9) is provided. This makes it possible to control so that C ₁ and C ₂ are different.

  In this embodiment, the number of organic solvent concentration control means is not limited to one. For example, two or more of the above control means may be used in combination. More specifically, (1) the exhaust means as shown in FIG. 6 and the ventilation means as shown in FIGS. 7 and 8 are combined (2) the exhaust means as shown in FIG. 6 and / or the ventilation as shown in FIG. (3) The first section 8A and the second section 8B are provided as shown in FIG. 9, and the exhaust as shown in FIG. 6 is further provided in the first section 8A. It is conceivable to provide means.

(Other processes)
In this embodiment, in addition to the printing process and the punching process, there may be other processes.
For example, there may be a drying step of drying the organic solvent contained in the ink portion 2. As a result, the ink dries quickly and workability and productivity can be improved.
As a specific method of drying, there is a method of applying hot air or warm air.
The drying step may be performed between the printing step and the punching step, or may be performed between the punching steps. However, from the viewpoint of controlling the concentration of the organic solvent in the air and stable perforation, it is preferably performed between the printing step and the perforation step.

<Method of manufacturing container for freshness of fruits and vegetables>
A container for freshness of fruits and vegetables can be manufactured by using the resin film having a hole manufactured by the above-described method for manufacturing a resin film having a hole. That is, the fruit and fruit freshness-keeping container can be manufactured by the container making step (and other steps as necessary) of making a container using the perforated resin film produced by the above-mentioned method for producing a perforated resin film. ..

As a concrete method for producing the container, a known method regarding bag making may be appropriately applied.
For example, as described in Examples below, two sheets of perforated synthetic resin film cut into a square having an appropriate size are prepared, and they are stacked, and three of the four sides of the square are heated. By sealing, a bag-shaped packaging container can be manufactured. The seal width of the heat seal is, for example, about 10 mm. Of course, the method of making the container may be another method.
During bag making, usually, the printed surface of the perforated synthetic resin film (the surface of the resin film 1 where the ink portion 2 is present) is located on the outer surface side of the bag.

The shape and size of the packaging container are not particularly limited as long as the fruits and vegetables can be packed. The shape of the packaging container is typically a bag shape, and more specifically, a rectangular (rectangular, square, etc.) bag shape.
This is just an example, but the size of the packaging container can be about 50 mm × 50 mm to 600 mm × 800 mm for the purpose of packaging fruits and vegetables for general consumers.

<Package with fruits and vegetables>
A package containing fruits and vegetables can be produced by packaging (sealing) the fruits and vegetables with the obtained container for keeping freshness of fruits and vegetables. For example, first, a packaging container for freshness of fruits and vegetables is prepared, and an appropriate amount of fruits and vegetables is housed in the inner space thereof. Then, the opening of the packaging container is heat-sealed (heat-sealed) to form a heat-sealed portion (sealing width is typically about 10 mm). By the procedure described above, it is possible to obtain a package containing fruits and vegetables in which fruits and vegetables are packaged. In this way, by packaging the fruits and vegetables in the freshness and packaging container for keeping fruits and vegetables, the freshness of the fruits and vegetables can be maintained (deterioration of the fruits and vegetables can be suppressed).
The opening may be closed by an adhesive tape, a rubber band, a string, a lid that can be closed, etc., instead of heat sealing. In short, any closing method may be used as long as the opening and closing of gas is sufficiently restricted.

  The fruits and vegetables that can be packaged are not particularly limited. Specific examples of fruits and vegetables include oba, spinach, komatsuna, mizuna, mibuna, asparagus, kushinsai, lettuce, thyme, sage, parsley, italian parsley, rosemary, oregano, lemon balm, chives, lavender, salad barnet, rum's ear, rocket. , Dandy lion, nastatum, basil, arugula, watercress, moloheiya, celery, kale, leeks, cabbage, Chinese cabbage, shungiku, sardana, sanchu, butterbur, nabana, bok choy, honeywort, seri, cabbages, broccoli, cauliflower, myoga, radish, Carrot, Burdock, Radish, Turnip, Sweet potato, Potato, Chinese yam, Yam, Taro, Ginenjo, Yamato, Bell pepper, Paprika, Shishitou, Cucumber, Eggplant, To Door, mini tomatoes, pumpkin, bitter gourd, okra, sweet corn, green soybean, peas, green beans, broad beans, Kinkinokorui, and the like. It is also effective on fruits such as citrus fruits, apples, pears, grapes, blueberries, persimmons, strawberries, and cut flowers.

<System>
In the above, the embodiment of the present invention has been described from the side of the “method for producing a perforated resin film”.
On the other hand, the present invention can be understood as the following "system".

"A system for producing a perforated resin film used for a container for freshness of fruits and vegetables,
A printing device section that prints an ink containing an organic solvent on at least a part of the resin film,
A perforation device section that irradiates a resin film with a laser beam from a laser light source to form a hole,
A system comprising: a control unit that controls the organic solvent concentration C ₁ near the printing device unit and the organic solvent concentration C _{2 in} the air near the punching device unit to be different. "

In the above system, the specific mode of the printing device unit has already been described with reference to FIGS. Further, since the specific mode of the punching device section has been described with reference to FIGS. 1, 4 and 5, etc., a further description will be omitted. Further, the control means for controlling so that C ₁ and C ₂ are different from each other has already been described with reference to FIGS.

  The embodiments of the present invention have been described above, but these are examples of the present invention, and various configurations other than the above can be adopted. Further, the present invention is not limited to the above-described embodiments, and modifications, improvements, etc. within the scope of achieving the object of the present invention are included in the present invention.

  Embodiments of the present invention will be described in detail based on examples and comparative examples. The present invention is not limited to the embodiments.

<Example 1>
With a system including an exhaust device 6 as shown in FIG. 6, printing by a gravure printing method and perforation using a laser irradiation device are performed in this order on a resin film while controlling the solvent concentration in the air. It was Thereby, a perforated resin film was obtained. The details will be described below.

First, as a resin film, an anti-fog biaxially oriented polypropylene film manufactured by Gunze Co., Ltd., a trade name “Silfan MV2” (thickness 40 μm) was prepared.
In addition, a commercially available gravure ink for packaging was prepared. This ink contained butyl acetate as a solvent.

  The above ink was printed on a part of one side of the resin film by using a gravure printing machine. At the time of this printing, by operating the exhaust device, a constant air flow was generated to prevent the organic solvent (butyl acetate) volatilized from the ink from moving to the vicinity of the laser irradiation device.

After printing the ink, holes were provided by irradiating the resin film with a CO ₂ pulse laser (maximum output 150 watts) using a laser irradiation device. The time between printing and laser irradiation was about 6 seconds.
Here, as the rotation support roll (reference numeral 14 in FIGS. 5 and 6), a roll having a diameter of 318 mm and a width of 725 mm has five grooves with a width of 5 mm and a depth of 5 mm at 100 mm intervals from positions 150 mm from both ends. A rotating support roll was used.
Further, regarding the laser irradiation device, the positions of laser irradiation of the five CO ₂ pulse lasers respectively correspond to the positions of the grooves of the rotation supporting roll, and the distance from the synthetic resin film is 10 to 15 mm. installed. At this time, the focus of the laser was set at a position slightly outside the film from the surface of the resin film opposite to the laser incident surface.
While rotating the rotation supporting roll, the film was run on the rotation supporting roll at a constant traveling speed, and pulse laser was irradiated from each laser irradiation device at constant intervals. At this time, nitrogen gas pressure was applied to the compressed gas introduction path, and nitrogen gas was blown from the nozzle tip along the laser beam during laser irradiation. Thereby, the film melted by laser irradiation was blown off.

  In Example 1, the concentration of butyl acetate at a location 50 cm from the location where the gravure roll was in contact with the resin film was measured by a detector tube method and found to be 0.01 vol%. The concentration of butyl acetate at a position 50 cm from the line connecting the tip of the laser irradiation device (where the laser light is emitted) and the point where the laser light hits the resin film was also measured in the same manner, and was 0 vol%. These values were almost constant during printing and punching.

<Comparative Example 1>
A perforated resin film was obtained in the same manner as in Example 1 except that the exhaust device 6 was not operated (that is, exhaust was not performed).
In Comparative Example 1, as a result of not controlling the organic solvent concentration, the concentration of butyl acetate at a location 50 cm from the location where the gravure roll contacts the resin film, and the tip of the laser irradiation device (where laser light is emitted) The concentration of butyl acetate at 50 cm from the line connecting the points where the laser light hits the resin film fluctuated drastically during the time of printing and perforation.

<Example 2>
A perforated resin film was obtained in the same manner as in Example 1 except that the resin film produced in the following manner was used as the resin film.
In the printing step, ink was printed on the resin outer layer side described below.

Nylon 6 (UBE Nylon (registered trademark) 1022B manufactured by Ube Industries, Ltd.) was prepared as a material for forming the resin outer layer constituting the outer surface of the packaging bag. Further, as a material for forming the resin inner layer constituting the inner surface of the packaging bag, an antifogging agent prepared by mixing glycerin laurate and decaglycerin laurate in a ratio of 97 parts by weight: 3 parts by weight is used as a material for ethylene / vinyl alcohol. The thing added so that it might be 2.5 weight% with respect to the polymer resin whole quantity was prepared.
These materials were put into a T-die extruder, and a resin film having a two-layer structure was produced by the co-extrusion T-die method.
The thickness of each layer of the obtained resin film was 12 μm for the layer made of nylon 6 and 18 μm for the layer containing the ethylene / vinyl alcohol copolymer resin.
Moreover, the contact angle of water on both surfaces of this resin film was measured. The contact angle on the outer resin layer side was 62 °, and the contact angle on the inner resin layer side was 25 °.

<Evaluation of whether or not holes can be stably formed>
Fifty holes of the perforated resin film obtained in Example 1 were randomly selected, and the shapes (contours) of these holes were enlarged and observed. All the holes observed were perfect circles with almost the same diameter.
The same applies to the holes of the perforated resin film obtained in Example 2.

  On the other hand, when 50 holes of the perforated resin film obtained in Comparative Example 1 were randomly selected and observed, it was found that the holes were substantially perfect circles, elliptical holes, and distorted shapes that were neither perfect circles nor ellipses. The holes were mixed and the sizes of the holes were different.

<Evaluation of freshness retention of fruits and vegetables>
Two sheets of the perforated synthetic resin film obtained in Example 1 cut into squares of appropriate size were prepared, and these were stacked. A bag-shaped packaging container was created by heat-sealing three sides of the four sides of the quadrangle.
Broccoli was placed in the prepared packaging container, and the opening was heat-sealed and closed to obtain a package containing fruits and vegetables.
This was left at 20 ° C. for 3 days, and the degree of deterioration was compared with that of unpackaged fruits and vegetables.
It was confirmed that the broccoli in the package was sufficiently suppressed in deterioration of fruits and vegetables as compared with unwrapped fruits and vegetables.
Also with the perforated synthetic resin film obtained in Example 2, the bag-shaped packaging container was prepared and the freshness retention of the fruits and vegetables (broccoli) was evaluated in the same manner as above. Also in this case, deterioration of fruits and vegetables was sufficiently suppressed.

<Other evaluations>
In the above evaluation of freshness retention of fruits and vegetables, when the degree of dew / cloudiness on the inner surface of the container after standing for 3 days at 20 ° C. was visually evaluated, Example 2 had less dew / cloudiness than Example 1.
Further, when the print quality was evaluated in Examples 1 and 2, sufficient print quality (no problem in practical use) was obtained in both Examples. However, in Example 1, with a lapse of time of about one month, peeling of the ink was recognized although it was very slight. On the other hand, in Example 2, such peeling was not observed.

DESCRIPTION OF SYMBOLS 1 Resin film 2 Ink part 2A Ink composition 5 Hole 6 Exhaust device 7 Air blower 8A First section 8B Second section 9 Cover 11 Unwinding roll 12 Winding roll 13 Laser irradiation device 14 Support roll 21 Guide roll 22 Ink pan 23 gravure roll 24 impression cylinder 24 hole 31 water supply device 32 ink supply device 33 plate cylinder 34 blanket cylinder 35 impression cylinder 40 pulse laser 41 light guide path 43 conical beam 44 compressed gas introduction path 45 nozzle tip 46 groove

Claims (14)

A method for producing a perforated resin film used for a container for maintaining freshness of fruits and vegetables,
A printing step of printing an ink containing an organic solvent on at least a part of the resin film, and a perforation step of forming holes by irradiating the resin film with a laser beam from a laser light source,
In an environment controlled such that the organic solvent concentration C _{1 in} the air near the place where the printing process is performed and the organic solvent concentration C ₂ in the air near the place where the perforation process is performed are different, A method for producing a perforated resin film, wherein the printing step and the perforating step are performed. It is a manufacturing method of the perforated resin film according to claim 1,
The method of manufacturing a perforated resin film, wherein the printing step and the perforating step are performed in this order. The method for producing a perforated resin film according to claim 1 or 2, wherein
The method for producing a perforated resin film, wherein the printing step and the perforation step are continuously performed while the resin film is running. It is a manufacturing method of the perforated resin film according to any one of claims 1 to 3,
The method for producing a perforated resin film, wherein the time between the printing step and the perforating step is 0.1 to 600 seconds. It is a manufacturing method of the perforated resin film according to any one of claims 1 to 4,
The method for producing a perforated resin film, wherein the control is performed by exhausting at least a part of the organic solvent volatilized from the ink. It is a manufacturing method of the perforated resin film according to any one of claims 1 to 4,
The method for producing a perforated resin film, wherein the control is performed by ventilating the air near the location where the printing step is performed and / or the air near the location where the perforation step is performed. It is a manufacturing method of the perforated resin film according to any one of claims 1 to 6,
The printing process is performed in the first section,
The punching step is performed in a second compartment different from the first compartment,
The method for producing a perforated resin film, wherein the control is performed by restricting movement of air between the first compartment and the second compartment. It is a manufacturing method of the perforated resin film according to any one of claims 1 to 7,
The perforated resin film, which is controlled by providing a member for restricting contact of air containing an organic solvent evaporated from the ink with the laser light source at or near the laser light source. Manufacturing method. It is a manufacturing method of the perforated resin film according to any one of claims 1 to 8,
The method for producing a perforated resin film, wherein the organic solvent contained in the ink contains at least one solvent selected from the group consisting of alcohol solvents, ketone solvents and ester solvents. It is a manufacturing method of the perforated resin film according to any one of claims 1 to 9,
Of the resin film which is printed and perforated not been made, ₁ and the contact angle of water theta in the first _surface, when the contact angle of water on the second surface and theta _2, the value of theta _{1 /} theta ₂ is greater than 1 Less than 9,
In the printing step, a method for producing a perforated resin film, wherein ink is printed on the first surface of the resin film. It is a manufacturing method of the perforated resin film according to any one of claims 1 to 10,
The method for producing a perforated resin film, wherein the C ₂ is smaller than the C ₁ . It is a manufacturing method of the perforated resin film according to any one of claims 1 to 11,
The method for producing a perforated resin film, wherein the C ₂ is 5 vol% or less.   A method of manufacturing a container for freshness of fruits and vegetables, which comprises a container making step of making a container using the resin film having a hole produced by the method for producing a resin film having a hole according to any one of claims 1 to 12. A system for producing a perforated resin film used for a container for freshness of fruits and vegetables,
A printing device section that prints an ink containing an organic solvent on at least a part of the resin film,
A perforating device section which irradiates a laser beam from the laser light source to the resin film to provide a hole,
A system comprising: a control unit that controls the organic solvent concentration C ₁ near the printing device unit and the organic solvent concentration C _{2 in} the air near the punching device unit to be different.

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