JPH05193018A - Manufacture of laminate - Google Patents

Abstract

PURPOSE:To manufacture a laminate having excellent strength simply at a low cost by a method wherein a polyolefin resin is melted and extruded at a specific temperature, treated with ozone under a molten state while being laminated on a laminating base material and matured only for a specific time at a specific temperature. CONSTITUTION:A polyolefin resin is extruded and laminated on a laminating base material, thus manufacturing a laminate. First, the polyolefin resin is melted and extruded at a temperature of 170-290 deg.C and treated with ozone under a molten state at that time. The ozone-treated polyolefin resin is laminated on the laminating base material, and matured for five min or more at a temperature from 50 deg.C to a temperature lower than the melting point in an olefin resin. Ozone treatment is conducted under conditions of 0.2g/hr.cm or more (conversion into ozone spray nozzle width). An oxygen impermeable laminating base material is used, and the polyolefin resin may also be matured for two hr or more. A metallized film or a metal foil is employed as the oxygen impermeable laminating base material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a laminate, and more specifically, it can be extrusion-laminated on a laminate base material without anchor coating, which simplifies the process and elutes the anchor coating agent. There is no danger, and a method that can produce a laminate suitable for food packaging, pharmaceutical packaging, etc., and extrusion lamination without anchor coating to an oxygen impermeable laminated base material, thus simplifying the process The present invention relates to a method for producing a laminated film suitable for boiling and retorting, which has no risk of the anchor coating agent being eluted at all.

[0002]

2. Description of the Related Art Conventionally, various laminates have been manufactured in order to utilize the characteristics of each resin or to reduce the defects, and further expect the synergistic effect thereof. There is. For example, a laminate is known which utilizes the properties of both a laminating substrate having an excellent gas barrier property and the like, and a polyolefin having an excellent chemical resistance and a low cost and excellent heat sealing property. Further, a method is also known in which a polyolefin is treated with ozone to enhance the adhesiveness when laminated. Furthermore, even after using such a laminated material, boil and retort treatment (bonding the contents of the laminated material into a container, heating the contents at 100 ° C. or more to heat and sterilize the contents), and then bond A material that retains the function as a laminated material such as the properties and gas barrier properties has also appeared.

Specifically, for example, since polyolefin is inactive and the adhesive strength is insufficient, the surface of the laminating substrate is treated with polyurethane, an isocyanate compound or the like.
A method has been proposed in which an anchor coat treatment is performed, and then the resultant is laminated with ozone-treated polyolefin (Japanese Patent Application Laid-Open No. 61-61160).
-283533). However, this method requires an anchor coat treatment facility, and there is a risk that the anchor coat agent may elute, which is a sanitary problem, so that the application is limited and the adhesive strength is insufficient. there were.

Therefore, there has been proposed a method for producing a laminate by subjecting it to ozone treatment under specific conditions without using an anchor coating agent (JP-A-63-49423).
However, in this case, there is a problem that the melt extrusion temperature is high and an odor is generated in the laminate, and it cannot be used for boiling and retorting.

[0005]

Means for Solving the Problems As a result of intensive research aimed at solving such problems as described above, the present inventors have conducted ozone treatment in a molten state on a polyolefin resin melt-extruded at a relatively low temperature, Then, after laminating on a laminating substrate (including an oxygen-impermeable laminating substrate) that has not been subjected to anchor coating treatment, the resulting laminated film (laminate) is aged (aged or aged) at an appropriate temperature and time. It was found that the bonding strength and heat sealing strength, or the bonding strength and heat sealing strength after boil or retort treatment, and oxygen impermeability are significantly improved by using annealing) without using an anchor coating agent. The present invention has been completed based on this finding.

That is, according to the present invention, when the polyolefin resin is extrusion-laminated on the laminated base material to produce a laminate, the polyolefin resin is 170 to 29.
After melt extrusion at a temperature of 0 ° C, ozone treatment in the molten state, then laminating on a laminating substrate, then 50 ° C
It is the above, and provides the manufacturing method of the laminated body characterized by ageing for 5 minutes or more at the temperature below the melting point of the said olefin resin.

Further, in the present invention, when a polyolefin resin is extrusion-laminated on an oxygen-impermeable laminated base material to produce a laminated film, the polyolefin resin is melt-extruded at a temperature of 170 to 260 ° C. and then melted. Laminated film for boil and retort, characterized by being subjected to ozone treatment in the state, then laminated on a laminating substrate, and then aged for 2 hours or more at a temperature of 80 ° C. or higher and below the melting point of the olefin resin. The present invention also provides a method of manufacturing the same.

There are various types of laminating substrates used in the method of the present invention. For example, various metal vapor deposition films such as silicon oxide vapor deposited polyethylene terephthalate (PET) film (GT film) and various metals such as aluminum foil. Examples include various stretched plastic films such as foils and biaxially stretched nylon films, unstretched plastic films, papers and nonwoven fabrics. Among these, as the laminating substrate used in the method of the present invention, various metal vapor deposition films such as silicon oxide vapor deposition PET film and various metal foils such as aluminum foil are particularly preferable. The thickness of these laminating substrates is not particularly limited and may be appropriately selected depending on the purpose and the like, but is usually about 5 to 50 μm. These laminating substrates may be subjected to surface treatment such as corona discharge treatment or flame treatment, if necessary, in order to improve the adhesiveness with the polyolefin resin to be laminated. However, no anchor coat treatment is performed in the method of the present invention.

In the case of producing a laminated film for boil and retort, an oxygen-impermeable one of the above-mentioned laminating substrates is used as the laminating substrate. Specifically, for example, silicon oxide vapor deposition PET
Various metal vapor deposition films such as films (GT films),
Examples include various metal foils such as aluminum foil, various stretched films such as ethylene / vinyl alcohol resin film and polyvinylidene chloride film, and unstretched films. Among these, various metal vapor deposition films such as silicon oxide vapor deposition PET film and various metal foils such as aluminum foil are particularly preferable.

The polyolefin resin used in the method of the present invention is not particularly limited, and examples thereof include polyethylene resins and polypropylene resins, which may be homopolymers or copolymers. It may be.
Further, it may be a blend of these. Among these, low density polyethylene is preferable as the polyolefin resin used in the method of the present invention, and linear low density polyethylene (LLDPE) is particularly preferable because it has excellent heat-sealing properties and heat resistance. The thickness of the polyolefin resin is not particularly limited and may be appropriately selected depending on the purpose and the like, but is usually about 10 to 200 μm.

In the method of the present invention, the above-mentioned polyolefin resin is melt-extruded at a temperature of 170 to 290 ° C., further subjected to ozone treatment in a molten state, then pressure-bonded to the above-mentioned laminated base material, and laminated (extrusion laminate). )
To do. As described above, according to the method of the present invention, a laminate is manufactured by the extrusion lamination method, but as described above, extrusion lamination is performed without subjecting the laminating substrate to the anchor coat treatment.

In the method of the present invention, the polyolefin resin is heated to a temperature of 170 to 290 ° C., preferably 230 to 290 ° C.
Melt extrude at a temperature of 290 ° C. If the temperature of the melt-extruded polyolefin-based resin exceeds 290 ° C, the polyolefin-based resin is decomposed and an odor is produced in the laminate, which is not preferable. On the other hand, if the temperature of the melt-extruded polyolefin-based resin is lower than 170 ° C., the adhesive strength of the laminate is lowered, which is not preferable.

In the case of producing a laminated film for boil and retort, the polyolefin resin as described above is melt extruded at a temperature of 170 to 260 ° C., further ozone-treated in a molten state, and then the above-mentioned laminated base material. It is pressure-bonded to and laminated (extrusion lamination). In the case of producing a laminated film for boil and retort, the polyolefin resin is melt extruded at a temperature of 170 to 260 ° C, preferably 230 to 260 ° C. If the temperature of the melt-extruded polyolefin-based resin exceeds 260 ° C., odor is generated in the laminated film and the oxygen barrier property is deteriorated, which is not preferable. On the other hand, when the temperature of the melt-extruded polyolefin resin is lower than 170 ° C., the adhesive strength of the laminated film is lowered, which is not preferable.

Next, the extruded polyolefin resin is subjected to ozone treatment in a molten state. That is, the surface of the polyolefin resin which is still in a molten state immediately after extrusion is subjected to ozone treatment to improve the adhesive strength. Here, the ozone treatment is 0.2 g / hr · in terms of ozone spray nozzle width conversion.
cm or more, preferably 0.5 to 3.0 g / hr · cm. Here, the ozone treatment amount is 0.2 g / h
If it is less than r · cm, sufficient adhesive force cannot be obtained. It is sufficient that the ozone treatment amount is 0.2 g / hr · cm or more, and even if it is 3 g / hr · cm or more, higher adhesiveness cannot be obtained.

In the method of the present invention, the polyolefin resin melt-extruded as described above is subjected to ozone treatment in a molten state, and then pressure-bonded to the above-mentioned laminated base material to laminate (extrusion lamination). Specifically, for example, pressure bonding lamination is performed between a metal roll and a rubber roll. Here, the metal roll has a role as a cooling roll, and is usually kept at a temperature of 5 to 70 ° C., preferably 15 to 50 ° C. The rubber roll may be made of silicone rubber or chloroprene rubber. The crimping linear pressure may be usually 5 to 40 kg / cm.

In the method of the present invention, extrusion lamination as described above is followed by aging (aging or annealing).
It is necessary to do. Here, the aging is performed at a temperature of 50 ° C. or higher and a temperature not higher than the melting point of the olefin resin for 5 minutes or longer, preferably at a temperature of 60 to 100 ° C.
It may be carried out for 30 minutes to 1 day. Here, if the treatment temperature during aging is lower than 50 ° C., sufficient adhesive force cannot be obtained, while if the treatment temperature is higher than the melting point, the laminate is deformed, which is not preferable. Further, if the treatment time is less than 5 minutes, the aging effect is insufficient and the adhesive strength is insufficient.

When producing a laminated film for boil and retort, aging is performed at 80 ° C. or higher, and
It may be carried out at a temperature not higher than the melting point of the olefin resin for 2 hours or longer, preferably at 90 to 120 ° C. for 3 hours to 1 day. Here, the processing temperature during aging is 80 ° C.
If it is lower than this, sufficient adhesive force cannot be obtained after boil or retort treatment. On the other hand, if the melting point is higher than the melting point, the laminated film is deformed. Also, the processing time is 2
If it is less than the time, the aging effect is not sufficient, and the adhesive strength after boil or retort treatment is insufficient.

In this way, the desired laminate (laminated film) can be obtained. The thickness of this laminate is usually about 15 to 250 μm.

[0019]

EXAMPLES Next, the present invention will be described in detail with reference to Examples.

Examples 1 to 16 and Comparative Examples 1 to 3 As a substrate for laminating, GT manufactured by Toyo Ink Mfg. Co., Ltd.
A film [a silicon oxide-deposited PET film (a film in which Si _x O _y was vacuum-deposited on one side of the PET film), grade: 1000R, thickness 12 μm] was used. On the other hand, LLDPE (ethylene / octene-1 copolymer, MI = 2 g / 10 minutes, manufactured by Idemitsu Petrochemical Co., Ltd., density is shown in Table 1) was used as the polyolefin resin. A diameter of the laminating substrate and the polyolefin resin is 5
Using a 0 mm extrusion laminator, the base material for lamination was laminated so as to sandwich the vacuum vapor deposition surface to obtain a laminate. The laminating speed (film feed speed) is 15
It was m / min, and the film thickness of the obtained laminate (laminate film thickness) was 100 μm. At this time, regarding the polyolefin resin in a molten state immediately after extrusion, before the above-mentioned lamination, at the resin temperature shown in Table 1 (however, this temperature shows the surface temperature of the polyolefin resin at the time of extrusion). The ozone treatment amount is 2 in terms of the ozone spray nozzle width.
The ozone treatment was performed under the condition of g / hr · cm.

The laminate (film) thus obtained was aged in air under the conditions shown in Table 1. Table 1 shows the adhesive strength and heat seal strength of the laminate after aging. The test methods for the adhesive strength and heat seal strength are as follows. Adhesive strength: A test piece having a width of 15 mm and a length of 100 mm was prepared, and the test piece was peeled by hand for 50 mm in the length direction, and then 300 m in a 180 degree direction with a tensile tester.
The strength when peeled at a tensile speed of m / min was measured. In addition, when it cannot be peeled by hand, it is defined as “not peelable”. Heat-sealing strength: Two test pieces having a width of 40 mm and a length of 100 mm were prepared, and the test pieces were heat-sealed so that the polyolefin resins were in contact with each other to prepare a test piece having a heat-seal width of 15 mm. Then, the strength when the test piece was peeled in a 180 ° direction at a tensile speed of 300 mm / min was measured by a tensile tester. The heat-sealing temperature was 200 ° C. except for 170 ° C. in Example 16.

[0022]

[Table 1]

Examples 17 to 24 and Comparative Examples 4 and 5 In Example 1, instead of the GT film manufactured by Toyo Ink Mfg. Co., Ltd. as the base material for laminating, an aluminum foil (manufactured by Sun Aluminum Co., Ltd., grade: 1100, thickness 20μ
m, a layer on which a polyolefin resin was laminated was subjected to corona discharge treatment at 30 w / m ² / min (watt density). )
Was used, the resin temperature was 280 ° C., and the laminate was produced in the same manner as in Example 1 except that the conditions were as shown in Table 2, and the adhesive strength and heat seal of the laminate after aging were produced. The strength was measured. The results are shown in Table 2.

[0024]

[Table 2]

Examples 25 to 34 and Comparative Examples 6 to 9 In Example 1, the biaxially stretched nylon (manufactured by Idemitsu Petrochemical Co., Ltd.) was used as the laminating substrate instead of the GT film manufactured by Toyo Ink Mfg. Co., Ltd. ， Grade: Unilon G10
0, thickness 15 μm) and used as a polyolefin resin LLDPE (ethylene / octene-1 copolymer, MI = 8 g / 10 min, density 0.910 g / c)
m ³ manufactured by Idemitsu Petrochemical Co., Ltd., the same as in Example 1 except that the laminating speed (film feed speed) was 80 m / min and the conditions shown in Table 3 were used. Then, a laminate having a film thickness of 30 μm was produced, and the adhesive strength and heat seal strength of the aged laminate were measured. The results are shown in Table 3.

[0026]

[Table 3]

Examples 35 to 40 and Comparative Examples 10 to 12 As a laminating substrate, GT manufactured by Toyo Ink Mfg. Co., Ltd.
A film [a silicon oxide-deposited PET film (a film in which Si _x O _y was vacuum-deposited on one side of the PET film), grade: 1000R, thickness 12 μm] was used. On the other hand, LLDPE (ethylene / octene-1 copolymer, MI = 2 g / 10 min, manufactured by Idemitsu Petrochemical Co., Ltd., density 0.928 g / cm ³ ) was used as the polyolefin resin. The laminating substrate and the polyolefin resin were laminated using an extrusion laminator having a diameter of 50 mm so as to sandwich the vacuum vapor deposition surface of the laminating substrate to obtain a laminated film. The laminating speed (film feeding speed) was 15 m / min, and the film thickness (laminating film thickness) of the obtained laminated film was 100 μm. At this time, regarding the polyolefin resin in the molten state immediately after extrusion, before the above-mentioned lamination, at the resin temperature shown in Table 4 (however, this temperature shows the surface temperature of the polyolefin resin at the time of extrusion). The ozone treatment was performed under the condition that the ozone treatment amount was 2 g / hr · cm in terms of ozone spray nozzle width conversion.

The laminated film thus obtained is
It was aged in the air under the conditions shown in Table 4, and further boiled as described below. The boil treatment was performed as follows. First, three sides of the laminated film (width 160 mm × length 300 mm) obtained as described above were heat-sealed over a width of 10 mm from 10 mm from each film end so that LLDPE was on the inside. Then, 1 liter of pure water was filled in the inside, and then top sealing was performed to prepare an evaluation sample (water-filled bag). The heat seal is 1k
It was performed at g / cm ² (contact pressure) for 1 second. As the heat seal temperature, a seal temperature having a high seal strength and a small variation was selected from the data of the seal temperature and the seal strength (actually, the heat seal was carried out at 200 ° C.). Water-filled bag) is placed in a hot water bath heated to 95 ° C, and the temperature is raised to 115 ° C in 12 minutes.
After the temperature was maintained for 30 minutes, the temperature was further lowered to 95 ° C over 30 minutes. The evaluation sample (water-filled bag) thus sterilized (boiled) was taken out from the hot water tank and cooled in pure water at about 20 ° C. for 10 minutes.

Table 4 shows the adhesive strength, oxygen permeation amount, haze, fusion resistance, and drop bag breaking strength of the evaluation sample (water-filled bag) before and after boil treatment. Table 4 also shows the performance before boil treatment (before sterilization). In addition, adhesive strength, heat seal strength, oxygen transmission rate,
The test methods for fusion resistance and drop-breaking bag strength are as follows. Adhesive strength: A test piece having a width of 15 mm and a length of 100 mm was prepared from the evaluation sample (water-filled bag) before and after the boil treatment, and after peeling the test piece by 50 mm in the length direction by hand, 180 degree direction with a tensile tester,
The strength when peeled at a tensile speed of 300 mm / min was measured. In addition, when it cannot be peeled by hand, it is defined as “not peelable”. Oxygen transmission rate: evaluated according to ASTM D 1434. Haze: A test piece was prepared from the evaluation sample (water-filled bag) before and after the boil treatment, and ASTM D 10
It was evaluated according to 03. Fusion resistance: The fusion state of the ears (four sides) of the evaluation sample (water-filled bag) was visually observed and evaluated in the following three stages. ○: No fusion, △: Some fusion (lightly peelable),
×: Complete fusion (or fusion inside the bag) Drop rupture strength: The evaluation sample (water-filled bag) after the boil treatment was stored at 23 ° C for 1 day, and further stored at 23 ° C in the room for 2 days. The strength of the dropped bag was measured. The drop-breaking bag strength was measured by measuring the sample for boil treatment (water-filled bag) in a horizontal state (the body of the bag was parallel to the floor surface), from a height of 2.5 m, to the concrete floor surface. Repeatedly dropped to confirm the number of drops until the bag was broken. Note that the number of repeated drops was 20 times per sample.

[0030]

[Table 4]

[0031]

According to the method of the present invention, a laminate having excellent adhesive strength and heat seal strength can be manufactured.
Moreover, according to the method of the present invention, since it is not necessary to perform the anchor coating treatment on the laminating substrate, the process can be simplified, the cost can be reduced, and the anchor coating treatment agent can be eluted. There is no danger of When an oxygen impermeable film is used, it is possible to produce a laminated film having excellent adhesive strength and heat seal strength even after boil or retort treatment, and excellent oxygen impermeability. Therefore, there is no concern about safety and health, the use of the laminate is not limited,
It can be effectively used for various purposes including a film for food packaging, a film for pharmaceutical packaging, and the like, and can be particularly effectively used as a film for boiling and retorting.

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Claims (5)

[Claims] 1. When a polyolefin resin is extrusion-laminated on a laminated base material to produce a laminate, the polyolefin resin is melt extruded at a temperature of 170 to 290 ° C., ozone-treated in a molten state, and then laminated. After laminating on a substrate, the temperature is 50 ° C or higher, and
A method for producing a laminate, which comprises aging at a temperature not higher than the melting point of the olefin resin for 5 minutes or more. 2. The method according to claim 1, wherein the ozone treatment is carried out under the condition of 0.2 g / hr · cm or more (converted into ozone blowing nozzle width). 3. When the polyolefin resin is extrusion-laminated on an oxygen-impermeable laminate base material to produce a laminated film, the polyolefin resin is added in an amount of 170 to
After melt extrusion at a temperature of 260 ° C., ozone treatment in a molten state and then laminating on a laminating substrate,
A method for producing a laminated film for boil / retort, which comprises aging for 2 hours or more at a temperature not lower than 0 ° C. and not higher than the melting point of the olefin resin. 4. The method according to claim 3, wherein the ozone treatment is carried out under the condition of 0.2 g / hr · cm or more (converted into ozone blowing nozzle width). 5. The production method according to claim 3, wherein the oxygen-impermeable laminate base material is a metal vapor deposition film or a metal foil.