JP2502479B2 - Porous organic film, method for producing the same, and freshness maintaining film for fruits and vegetables - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous organic film having a large number of fine unpenetrated pores, a method for producing the same, and a fresh fruit and fruit keeping film.

[0002]

2. Description of the Related Art Conventionally, a general-purpose olefin resin (for example, polyethylene) is filled with a large amount of fine inorganic powder (usually 50% by volume or more with respect to the resin), then formed into a film, and further uniaxial or biaxial It is known that a porous polyethylene film is formed by forming a fracture hole at the interface with the inorganic powder by stretching at a high draw ratio and opening microscopic holes that are continuous in a labyrinth. However, the porous film produced by such a method has a problem in that the inherent properties (eg, strength, softness, transparency, etc.) of the resin constituting the film are significantly reduced because a large amount of inorganic powder is added.

Further, there is known a method of punching an olefin resin film by a mechanical punching method such as a needle punching method or a hot-melt punching method. The needle punching method is a method in which a heated needle is pressed against a thermoplastic resin film to form a hole. The hot-melt perforation method is a method of perforating a thermoplastic resin film by melting it with a heated embossing roll.

However, according to the mechanical perforation method, the size of the holes is as large as about 100 μm, and it is difficult to perforate finer holes, and the density of the holes is high (for example, 500 or more per 1 cm ² ). Therefore, it is difficult to perforate and it is difficult to apply to various functional films.

An object of the present invention is to provide a porous organic film having a large number of fine unpenetrated pores having uniform pore diameters and useful as various functional films, packaging materials and the like. Another object of the present invention is to provide a method capable of producing the porous organic film in a simple and mass-production manner. Still another object of the present invention is to provide a freshness-keeping film for fruits and vegetables having an increased permeation amount of oxygen gas and water vapor.

[0006]

The porous organic film according to the present invention has a large number of non-through holes in the organic film.
It is characterized by being uniformly perforated at a density of 00 / cm ² or more.

Examples of the organic film include general-purpose polymer films such as polyethylene, polypropylene, polyethylene terephthalate, polyester, polyvinyl chloride, polyester, fluororesin and polyamide, engineering plastic films such as polycarbonate and polyimide, or polyether ether. Super engineering plastic film such as ketone or polyether ketone, or elastomer film,
In addition, a heat-fusible resin film, foamed paper, or the like can be used.

The pore size of the non-penetrating pores formed in the organic film is arbitrarily selected depending on the application. It is desirable that the diameter of the unpenetrated hole is, for example, 80 μm or less. The density of the non-penetrating holes perforated in the organic film needs to be 500 holes / cm ² or more. The density of the non-penetrating pores in the organic film depends on the diameter of the pores, but can be up to 20,000 by the method described later.
It is possible to increase the number to 0 / cm ² . Therefore, the density of the non-penetrating pores in the organic film is 500 / cm depending on the relationship with the pore diameter of the non-penetrating pores and the application.
It is possible to arbitrarily select in the range of ^{2 to} 200,000 pieces / cm ² .

Such a porous organic film is a long organic film between a first roll having a large number of particles having a Mohs hardness of 5 or more having sharp corners attached to the surface and a second roll having a smooth surface. The first roll by allowing the system film to pass through and adjusting the pressing force to the long organic film passing between the rolls to be uniform over the entire film surface in contact with the rolls. It is manufactured by biting sharp corners of a large number of particles on the surface into the long organic film to uniformly perforate a large number of fine unpenetrated holes at a density of 500 / cm ² or more.

The first roll has a structure in which a large number of particles having a Mohs hardness of 5 or more having sharp corners on the surface of a metal roll body are electrodeposited or attached by an organic or inorganic binder. Examples of the particles having a Mohs hardness of 5 or more include cemented carbide particles such as tung ten carbide, silicon carbide particles, boron carbide particles, sapphire particles, cubic boron nitride (CBN) particles, natural or synthetic diamond particles, and the like. Can be mentioned. In particular,
Synthetic diamond particles having high hardness and strength are desirable. It is desirable to use particles having a particle diameter of 10 to 100 μm and a variation in particle diameter of 5% or less. It is desirable that 50% or more of the large number of particles adhere to the surface of the roll body from the viewpoint of forming unpenetrated holes in the long organic film at a density of 500 / cm ² or more.

The second roll is, for example, an iron roll, an iron-based alloy roll, an iron roll whose surface is plated with Ni or Cr, a stainless roll, or a relatively soft metal such as brass, aluminum or copper. It is possible to use a roll made of, or a metal roll body having a surface coated with a polymer resin layer. As the polymer resin, various resins can be used, but urethane resin, silicone rubber and the like, which have a high buffering effect on the long organic film, are particularly preferable.

The perforation of the non-penetrating holes in the long organic film adjusts the pressing force to the long organic film passing between the first and second rolls, and the second roll is used. This is achieved by forming the surface from a soft one.

The freshness keeping film for fruits and vegetables according to the present invention comprises an organic film and a large number of fine unperforated holes uniformly perforated at a density of 500 pieces / cm ² or more.
A through hole, wherein the bottom of the non-through hole is located
Check that the remaining film thickness of the organic film is 10 μm or less
It is a feature .

Examples of the organic film include polypropylene films such as biaxial centrifugal polypropylene film and casting polypropylene film, polyethylene film and polyethylene terephthalate film. The freshness keeping film for fruits and vegetables according to the present invention has an oxygen transmission amount of 6000 to 20000 cc / m ² ·
It is preferably 24 hours · 23 ° C.

[0015]

The porous organic film according to the present invention has a large number of fine unpenetrated pores of 500 per cm ^{2 in the} organic film.
Since the organic film is formed of a polymer such as polyethylene because it is uniformly perforated with the above density and the pore diameters of the large number of non-penetrating pores are uniform, the non-penetrating pores have no liquid permeability. It is possible to obtain a functional film having oxygen gas permeability, carbon dioxide gas permeability, and water vapor permeability due to the remaining ultrathin film portion corresponding to the holes.

Specifically, it can be used as a functional packaging material for maintaining freshness of fruits and vegetables. That is, when the fruits and vegetables are hermetically packed, the oxygen concentration in the packaging material decreases due to the breathing action of the fruits and vegetables and the carbon dioxide concentration increases, and the respiration is suppressed by the addition of low oxygen and high carbon dioxide conditions. Freshness is maintained. In this case, the gas permeability of the film, which is the material of the packaging material, is that the minimum amount of oxygen that allows individual fruits and vegetables to breathe normally and maintain life forms, and the concentration of carbon dioxide gas generated by breathing does not become excessive. Controlled, that there is no condensation that causes bacterial growth,
Etc. are required. The porous organic film according to the present invention is formed with a large number of fine non-through holes in the organic film evenly, and by dissolving and diffusing gas of the film material in the remaining ultra-thin film portion corresponding to the non-through holes. Since the amount of permeation of oxygen, carbon dioxide and water vapor is greatly increased, the packaging material made from such a film has an excellent freshness-maintaining action for fruits and vegetables.

According to the method of the present invention, a long organic system is provided between a first roll having a large number of particles having a Mohs hardness of 5 or more having sharp corners attached to the surface and a second roll having a smooth surface. While passing the film, by adjusting the pressing force to the long organic film passing between the rolls to be uniform over the entire film surface in contact with the rolls, the long organic The sharp corners of a large number of particles on the surface of the first roll are made to bite into the long organic film to form a large number of fine unpenetrated holes at 500 / cm ² without substantially impairing the original characteristics of the system film. It is possible to uniformly perforate with the above density, and it is possible to mass-produce the porous organic film useful as the above-mentioned functional film and the like.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 is a front view showing an apparatus for manufacturing a porous film used in the present embodiment, FIG. 2 is a side view showing a main part of the apparatus shown in FIG. 1, and FIG. 3 is a cross section taken along line III-III in FIG. FIG.

In FIG. 1, reference numeral 101 denotes a bed. A table 102 is provided on the upper surface of the bed 101 except near the right end. Two key-shaped frames 103 are installed on the table 102 at predetermined intervals in the width direction of the table 102. The frame 103 includes a lower plate 103a, side plates 103b and an upper plate 1.
It is formed from 03c. First bearings 104 are built in the middle of the side plates 103b of each frame 103.
The boxes 105 are fixed. A first roll 106 is arranged between the frames 103. As shown in FIG. 2, the first roll 106 has a large number of particles with a Mohs hardness of 5 or more (for example, synthetic diamond particles) 10 having a grain size of 70 to 85 μm and sharp corners, for example.
7 comprises an iron roll body 108 electrodeposited on the surface thereof at an area ratio of 70% or more, and shafts 109 penetrating the center of the body 108 and projecting from both end faces of the body 108. Both protruding ends of the shaft 109 are respectively supported by bearings 104 in the first box 105. One end side of the first roll 106 (for example, the left end side)
The shaft 109 passes through the box 105, and a gear 111 that meshes with a gear of a drive shaft of a motor (not shown) is mounted on a protruding portion of the shaft 109. Therefore, the first roll 106 is driven by driving the motor.
Is rotated, for example, clockwise.
A protruding portion of the shaft 109 located between the gear 111 and the left side surface of the box 105 includes a gear 110
Is pivoted.

Rails 112 and 113 are formed on the side plates 103b of the frames 103 located below and above the first box 105, respectively.
As shown in FIG. 3, sliders 114 (the other slider is not shown) are vertically movably arranged on the lower rails 112, respectively. Each slider 11
Second boxes 116 each having a bearing 115 built therein are fixed to the shafts 4, and can be vertically moved along the rails 112. A second roll 117 is disposed between the frames 103 so as to face the first roll 106 below the first roll 106. The second roll 117 is composed of a roll main body 118 having a hard surface made of, for example, stainless steel, and a shaft 119 penetrating the center of the main body 118 and protruding from both end surfaces of the main body 118. Both protruding ends of the shaft 119 are axially supported by bearings 115 in the second box 116. One end side of the second roll 117 (for example, the left end side)
A shaft 119 portion projects through the second box 116, and a gear 120 meshing with the gear 110 of the shaft 109 of the first roll 106 is mounted on the projecting portion of the shaft 119. . Therefore, the second roll 117 is connected to the second box 116 and the slider 1.
By means of 14, it is arranged movably up and down along the rail 112. Further, the first roll 106 is driven by the motor.
By rotating the shaft 109 clockwise, the shaft 119 having the gear 120 meshing with the gear 110 of the shaft 109 rotates counterclockwise, and as a result, the second roll 117 rotates counterclockwise. It is designed to rotate clockwise.

As shown in FIG. 3, a slider 121 (the other slider is not shown) is disposed on each of the upper rails 113 so as to be vertically movable. A third box 123 having a bearing 122 built therein is fixed to each of the sliders 121, and can be moved up and down along the rails 113. In addition, a third roll 124 is provided between the respective frames 103 by the first roll 10.
6 are arranged so as to face each other. The third roll 124 is, for example, an iron roll body 1 having a surface coated with a polymer resin layer 125 such as urethane resin.
26 and the main body 12 through the center of the main body 126.
6 and shafts 127 projecting from both end surfaces thereof. Both protruding ends of the shaft 127 are axially supported by the bearings 122 in the third box 123. The shaft 12 on one end side (for example, the left end side) of the third roll 124
The seven parts protrude through the third box 123, and a gear 128 that meshes with the gear 110 of the shaft 109 of the first roll 106 is mounted on the protruding part of the shaft 127. Therefore, the third roll 124 is vertically movably arranged along the rail 113 by the third box 123 and the slider 121. Further, the shaft 109 of the first roll 106 is driven by the motor.
By rotating clockwise, the shaft 109 is rotated.
Shaft 127 having said gear 128 meshing with said gear 110 rotates counterclockwise, resulting in said third gear
The roll 124 is adapted to rotate counterclockwise.

The two frames 103, the two first boxes 105, the first roll 106, the two sliders 112 and 113, the two second boxes 116, the second roll 117, and the two The three boxes 123 and the third roll 124 constitute a perforation unit 129.

A cylindrical body 13 having upper and lower flanges 130 and 131 is provided on the lower wall of the two second boxes 116.
2 are arranged respectively. Each of the cylindrical bodies 132 is
As shown in FIG. 3, from the upper flange 130 to the second
A plurality of screws 133 screwed to the lower wall of the box 116 are fixed to the second box 116. A disc 135 having a hole 134 in the center thereof is disposed on the lower flange 131 of each of the cylindrical bodies 132,
Each of the disks 135 is fixed to each of the disks 135 by a plurality of screws 136 screwed to the lower flange 131. A coil spring 137 is housed in each of the cylindrical bodies 132 so as to apply an elastic force in the vertical direction. A rod 139 having a pressure sensor 138 attached to the upper end thereof is inserted into each of the cylindrical bodies 132 through a hole 134 of the disc 135.
Each of the pressure sensors 138 is in contact with the lower end of each of the coil springs 137, and can detect a pressing force on the coil spring 137 due to the rise of each of the rods 139. A disk-shaped guide 140 for smoothly moving the rod 139 up and down is attached to the rod 139 portion below each sensor 138. A ball screw 14 is attached to the lower end of each rod 139.
1 are respectively inserted. Each ball screw 1
41 penetrates the lower plate 103a of the frame 103 and projects into the recesses (not shown) of the bed 102. A casing (the other casing is not shown) 142 having a threaded engagement plate (not shown) is provided in each of the recesses. A lower end protruding portion of the ball screw 141 is screwed into the engagement plate in each casing 142. Worm shafts (not shown) that engage with the lower end protrusions of the ball screws 141 are respectively inserted in the casings 142 from the horizontal direction, and a handle is provided at one end of each worm shaft (the other handle is a (Not shown) 143 are provided respectively. Therefore, when the handle 143 is rotated, the ball screw 141 engaging with the worm shaft of the handle 143 is rotated, and the rod 139 having the ball screw 141 inserted therein is moved up (or down). ing. In this case, when the rod 139 is lowered by a certain distance or more, the disc-shaped guide 140 attached to the rod 139 comes into contact with the inner surface of the disc 135 below the cylindrical body 132 to lower the cylindrical body 132 itself. Let Therefore, the second box 116 fixed to the upper end of the cylindrical body 132 is lowered by the slider 114 along the lower portion 112 of the rail.

The two cylindrical bodies 132, the two disks 135, the two coil springs 137, the two pressure sensors 138, the two rods 139, the two disk guides 140, and the two ball screws 14
1, a first pressure adjusting the pressing force to the film passing between the first and second rolls 106 and 117 by the two casings 142, the two worm shafts (not shown) and the two handles 143. The adjusting means 144 is configured.

On the upper wall of the two third boxes 123, a cylindrical body 14 having upper and lower flanges 145 and 146 is provided.
7 are arranged respectively. Each of the cylindrical bodies 147 is
As shown in FIG. 3, from the lower flange 146 to the third
The plurality of screws 148 screwed to the upper wall of the box 123 are fixed to the third box 123. On the upper flange 145 of each of the cylinders 147, there is arranged a disc 150 having a hole 149 in the center,
In addition, each of the disks 150 is fixed by a plurality of screws 151 screwed from the disks 150 to the upper flange 145. A coil spring 152 is housed in each of the cylindrical bodies 147 so as to apply an elastic force in the vertical direction, and the lower end of each coil spring 152 is brought into contact with the upper wall of the third box 123. There is. A rod 154 having a pressure sensor 153 attached to the lower end thereof is provided in each of the cylindrical bodies 147.
It is inserted through 50 holes 149. The pressure sensors 153 are in contact with the upper ends of the coil springs 152, and the coil springs 152 are moved by lowering the rods 154.
It is possible to detect the pressing force to. A disc-shaped guide 155 for smoothly moving the rod 154 up and down is provided on the rod 154 above the sensors 153.
Are attached respectively. Ball screws 156 are inserted into the upper ends of the rods 154, respectively. Each of the ball screws 156 penetrates the upper plate 103c of the frame 103 and passes through the upper plate 103c.
Projecting above. On the upper surface of each of the upper plates 103c, a casing (the other casing is not shown) 157 in which a threaded engagement plate (not shown) is incorporated is provided. The upper end protruding portion of the ball screw 156 is screwed into the engagement plate in each casing 157. Worm shafts (not shown) that engage with the upper end protrusions of the ball screws 156 are respectively inserted into the casings 157 from the horizontal direction, and a handle is provided at one end of each worm shaft (the other handle is a (Not shown) 158 are provided respectively. Therefore, when the handle 158 is rotated, the ball screw 156 engaging with the worm shaft of the handle 158 is rotated, and the ball screw 15 is rotated.
6 descends (or ascends) the rod 154 with the inserted 6
It is supposed to do. In this case, when the rod 154 is raised above a certain distance, the disc-shaped guide 155 attached to the rod 154 causes the cylindrical body 147 to move.
The cylindrical body 147 itself is raised by contacting the inner surface of the upper disk 150. Therefore, the third box 123 fixed to the lower end of the cylindrical body 147 is attached to the slider 12.
1 raises along the rail 113.

The two cylindrical bodies 147, the two disks 150, the two coil springs 152, the two pressure sensors 153, the two rods 154, the two disk guides 155, and the two ball screws Fifteen
6. The second pressure for adjusting the pressing force on the film passing between the first and third rolls 106 and 124 by the two casings 157, the two worm shafts (not shown), and the two handles 158. The adjusting means 159 is constituted.

In front of the perforating unit 129, a winding roll (not shown) of a long film is disposed.
61, between the first and second rolls 106 and 117 of the unit 129 and the first and third rolls 10
6, 124. An electrostatic removing unit 162 is arranged at the subsequent stage of the unit 129. The static electricity removing means 162 is installed on the table 102,
It comprises a container 163 containing pure water and an ultrasonic wave generating member (not shown) for applying ultrasonic waves to the pure water. The unit 129 and the static elimination means 162
During the operation, five feed rolls 161 for transporting the long film that has passed between the first and third rolls 106 and 124 are arranged in the container 163 and at a subsequent stage of the container 163, respectively. I have. In addition, the container 16
The contact rolls 164 are respectively disposed on the two feed rolls 161 located at the front and rear stages of No. 3. A plurality of hot-air jetting members and a take-up roll (all not shown) for drying the film that has passed between the feed roll 161 and the abutment roll 164 are sequentially disposed at a stage subsequent to the static electricity removing unit 162. Have been.

Example 1 The first and third rolls 106, 12 of the perforating unit 129 in the porous film manufacturing apparatus having the above-described structure.
A method for producing a porous polyester film by perforating a long film made of polyester between 4 will be described with reference to FIGS.

First, as shown in FIG. 4, by rotating the two handles 143 of the first pressure adjusting means 144 in, for example, a counterclockwise direction, each of the drilling units 129 connected to the upper end of each cylindrical body 132 is rotated. The second box 116 is moved by the slider 114 to each rail 1 of each frame 103.
12 and lower each second box 1
The second roll 117 supported by the bearing 115 in the roller 16 is separated from the first roll 106 thereon by a sufficient distance. Also, the two handles 1 of the second pressure adjusting means 159
Each third box 123 connected to the lower end of each cylindrical body 147 by rotating
Is raised by the slider 121 along each rail 113 of each frame 103, and the third roll 124 supported by the bearing 122 in each of the third boxes 123 is separated from the first roll 106 thereunder by a sufficient distance. Open and release. In such a state, a long film 16 made of polyester having a thickness of 25 μm is wound from a winding roll (not shown).
After passing the tip of 0 between the first and second rolls 106 and 117 of the unit 129 and between the feed roll 161 and the first and third rolls 106 and 124 by the two feed rolls 161, the four feeds are performed. The leading end of the long film 160 is wound around a winding roll (not shown) by passing through the inside of the container 163 of the static electricity removing means 162 by the roll 161. When passing the long film 160 between the first and second rolls 106 and 117, as shown in FIG.
6 Avoid contact with the surface.

Next, after winding the leading end of the long film 160 on a winding roll, the second pressure adjusting means 15 is used.
9 by rotating the two handles 158 in the counterclockwise direction, the third boxes 123 connected to the lower ends of the respective cylindrical bodies 147 are respectively lowered by the sliders 121 along the respective rails 113 of the respective frames 103, The third roll 124 supported by the bearing 122 in each of the third boxes 123 is brought into contact with the first roll 106 thereunder. Further, by rotating each of the handles 158 in the same direction, each sensor 152 at the lower end of each rod 154 compresses each coil spring 152 therebelow. Due to the compression of each coil spring 152, a pressing force is applied to the upper wall of each third box 124, and the third roll 12 pivotally supported by the bearing 122 in the third box 123.
4 and the pressing force between the first roll 106 increases. At this time, the pressure sensor 152 causes the third roll 12 to move.
4 and the first roll 106 are detected and the rotation of each handle 158 is adjusted in the forward and reverse directions to detect the pressing force (compressive force) between the third and first rolls 124 and 106.
The pressing force on the long film 160 located between them is adjusted. Due to the adjustment of the pressure applied to the unit 129 by the second pressure adjusting means 159, uniform pressing is performed over the entire width direction of the long film 160 located between the third and first rolls 124 and 106. The pressure is applied and the preparation for the drilling operation is completed.

After the preparation for the boring operation is completed, ultrasonic waves are applied to the pure water contained in the container 163 of the static electricity removing means 162 by an ultrasonic generating member (not shown). Continuing,
By rotating the take-up roll and the drive shaft of a motor (not shown) at the same time, the gear of the drive shaft and the gear 11 of the shaft 109 of the first roll 106 are rotated.
By the rotation transmission of 1, the first roll 106 is rotated in the clockwise direction. When the first roll 106 rotates,
The third roll 124 is rotated in the counterclockwise direction by the rotation transmission of the gear 110 of the shaft 109 and the gear 128 of the shaft 127 of the third roll 124. in this case,
Since the second roll 117 is sufficiently spaced above the first roll 106, the second roll 117
The gear 120 of the shaft 119 and the first roll 106
The meshing of the gear 110 of the shaft 109 is released, and the second roll 117 is not driven by the rotation of the motor and becomes free rotation. By thus rotating the first and third rolls 106 and 124, the long film 160 passing between the rolls 106 and 124.
Is perforated.

That is, as shown in FIG. 2, the first roll 106 has an iron roll body 108 on which a large number of synthetic diamond particles 107 having sharp corners are electrodeposited on the surface at an area ratio of 70% or more. The third roll 124 has a structure, and has a roll main body 126 whose surface is coated with a polymer resin layer 125 such as urethane resin. Further, by adjusting the pressure applied to the unit 129 by the second pressure adjusting means 159,
A uniform pressing force is applied over the entire contact surface between the long film 160 and the rolls 106 and 124 passing between the first and third rolls 106 and 124. For this reason,
When the long film 160 made of the polyester passes between the first and third rolls 106 and 124, a large number of synthetic diamond particles 107 on the surface of the first roll 106 push the film 160 onto the film 160. The pressure is relieved by the polymer resin layer 125 and bites in, and the non-through holes are uniformly formed without substantially impairing the original properties of the polyester film.

Next, the long porous polyester film 167 perforated by the unit 129 is passed and conveyed into the container 163 of the perforated dust removing means 162 by the five feed rolls 161 and the two contact rolls 164. Since the perforation of the long porous polyester film 167 by the unit 129 is mainly based on the friction of the first and second rolls 106 and 117, the long porous polyester film after the perforation treatment. A large amount of static electricity is generated on the surface of 167, and surrounding dust is attached. The perforated porous polyester film 167 is passed through a container 163 containing pure water of the static electricity removing means 162, and ultrasonic waves are applied to the pure water by an ultrasonic wave generation member (not shown). Thus, the dust attached to the long porous polyester film 167 is washed away. Subsequently, the long porous polyester film 167 is passed through a plurality of hot air jetting members (not shown) to volatilize and remove water on the surface, and then wound on a winding roll (not shown).

The long porous polyester film 167 manufactured by the method of the first embodiment as described above is shown in FIG.
As shown in (4), a large number of unperforated holes 168 having a fine size with an opening diameter of 35 to 40 μm were perforated uniformly at a density of 5000 holes / cm ² .

It was confirmed that the long porous polyester film of Example 1 is useful as a clothing material and other functional films because it has excellent water pressure resistance and moisture permeability.

In Example 1, the organic film was made of polyester, but fluororesin, polyamide,
Even if a film made of another polymer such as an elastomer is used, it is possible to obtain a porous organic film having excellent properties similar to those in Examples 1 and 2.

Examples 2 to 4 A biaxial centrifugal polypropylene (OPP) film having a thickness of 20 μm was used as a long organic film, and a large number of synthetic diamond particles having a particle size of 50 to 60 μm and sharp corners were used as a first roll. Having a metal-made iron roll main body on the surface of which the pressing force against the long organic film passing between the first and third rolls is 500 kg, 20
By the same method as in Example 1 except that the pressure was 0 kg and 50 kg, approximately 1000 through holes having a fine size with an opening diameter of 20 μm were formed.
Three kinds of long porous OPP films were manufactured by perforating a large number and uniformly at a density of 0 pieces / cm ² .

With respect to each of the long porous OPP films obtained, the thickness of the remaining ultrathin film portion corresponding to the non-penetrating pores, the amount of oxygen permeation and the amount of water vapor permeation were measured. The results are shown in Table 1 below.

[0039] Table 1 remaining ultra-thin section an oxygen permeability of ^{1 *} water vapor permeability of ^{2 *} thickness ([mu] m) Example 2 2 1.0 ~2.0 × 10 ⁵ 8~10 Example 3 5 1.0 ~2.0 × 10 ⁴ 5~ 7 Example 4 10 2.0 × 10 ³ 3-4 The unit of oxygen permeation rate ^{1 *} is cc / m ² · 24 hr · 23 ° C The unit of water vapor permeation rate ^{2 *} is g / m ² · 24 hr · 40 ° C · 90 % RH As is clear from Table 1, it is understood that the oxygen permeation amount and the water vapor permeation amount can be controlled by adjusting the thickness of the remaining ultra-thin film portion corresponding to the non-through holes. Particularly, the porous OPP film of Example 4 has an oxygen transmission amount of 6000 to 200.
It is suitable as a packaging material for maintaining freshness of fruits and vegetables, which is required to have a temperature of 00 cc / m ² · 24 hr · 23 ° C.

[0040]

As described in detail above, according to the present invention, a porous organic film having a large number of non-penetrating pores of uniform pore size and useful for various functional films, etc. It is possible to provide a method that can be produced simply and in a mass-produced manner, and a freshness-maintaining film for fruits and vegetables whose oxygen transmission rate and water vapor transmission rate are controlled.

[Brief description of drawings]

FIG. 1 is a front view showing an apparatus for producing a porous film used in an example of the present invention.

FIG. 2 is a side view showing a main part of the manufacturing apparatus of FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG.

FIG. 4 is a front view for explaining the manufacturing process of the first embodiment.

FIG. 5 is a cross-sectional view showing a long porous polyester film manufactured according to Example 1.

[Explanation of symbols]

101: bed, 102: table, 103: frame, 105: first box, 106: first roll, 11
6 ... 2nd box, 117 ... 2nd roll, 123 ... 3rd
Box, 124: Third roll, 129: Perforating unit, 132, 147: Cylindrical body, 137, 152: Coil spring, 151, 143, 158, 175: Handle, 1
44, 159 ... Pressure adjusting means, 160 ... Long film, 162 ... Electrostatic removing means, 165, 167 ... Long porous polyester film, 168 ... Unpenetrated hole.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B29L 7:00 B29L 7:00 C08L 23:02 C08L 23:02

Claims (4)

(57) [Claims] 1. A porous organic film formed by uniformly perforating an organic film with a large number of fine unpenetrated holes at a density of 500 / cm ² or more. 2. A long organic film is passed between a first roll having a large number of particles having a Mohs hardness of 5 or more having sharp corners attached to the surface and a second roll having a smooth surface, and The pressing force on the long organic film passing between the rolls is adjusted to be uniform over the entire film surface in contact with the rolls.
It is characterized in that sharp corners of a large number of particles on the roll surface are bitten into the long organic film to form a large number of fine unpenetrated holes uniformly at a density of 500 / cm ² or more. Item 2. A method for producing a porous organic film according to item 1. 3. An organic film and this organic film
A large number of holes uniformly perforated at a density of 500 / cm ² or more
Of the fine non-penetrating holes of the
The thickness of the remaining thin film portion of the organic film to be placed is 10 μm or less.
A fruit and vegetables freshness-keeping film characterized by being below . 4. uniformly perforated a number of minute non-through hole in a biaxially oriented polypropylene film at 500 / cm ² or more densities, and the oxygen permeation amount 6000~20000cc
/ M ² · 24 hr · 23 ℃, freshness preservation film for fruits and vegetables, characterized in that.