JPS6036387B2 - Membrane laminate - Google Patents

Description

[Detailed description of the invention] The present invention relates to a novel membrane laminate.

Membrane laminates have traditionally been used to impart properties such as moisture resistance, oil resistance, abrasion resistance, heat sealability, and gas barrier properties to base materials such as thermoplastic resin films and sheets, cellophane, paper, cloth, and aluminum foil. It has been used as an excellent packaging material.

However, in extrusion lamination, which is a typical manufacturing method for film-like laminates, molten resin is extruded from an extruder into a film onto a moving base material, and the film is crimped between a casting roll and a nip roll. It is stretched to high magnification in a narrow space and pulled off at high speed.

Therefore, the resins used in extrusion lamination have been limited to resins with excellent drawdown properties, such as low-density polyethylene and ethylene-vinyl acetate copolymer ionomers. On the other hand, polypropylene has the advantage of being superior to polyethylene in terms of heat resistance, oil resistance, anti-corrosion properties, transparency, etc., as well as being strong and easy to process.

Therefore, this polypropylene is biaxially oriented polypropylene,
Polypropylene is attracting attention as a material for extrusion laminates because by laminating it onto a transparent film substrate such as cellophane, a film-like laminate with strong heat-sealing strength can be obtained without impairing the transparency of the substrate. However, polypropylene has poor drawdown properties required when manufacturing the film-like laminate, and surging occurs when extrusion laminating is performed at a high speed of 3 h/min or higher, making it impossible to laminate a uniform thin film. There is. If polypropylene with a sufficiently large melt flow index (hereinafter abbreviated as M plate) is used, extrusion lamination can be carried out at a sufficiently high speed for industrial purposes. It has not yet been put into practical use due to the disadvantage of not having any sexual characteristics.

Furthermore, if polypropylene with a small M'1 is used, a film-like laminate with excellent mechanical strength, heat sealability, and transparency can be obtained, but it has the disadvantage of poor high-speed processability. In this way, conventional technology uses polypropylene,
It was not possible to obtain a film-like laminate product that simultaneously satisfied all of high-speed processability, mechanical strength, heat sealability, and transparency. As a method for improving the extrusion lamination processability of polypropylene as described above, a method of adding low density polyethylene to polypropylene has been proposed. A good film-like laminate can be obtained.

However, in this case, it is necessary to add a step to add low-density polyethylene, which is not only disadvantageous industrially, but also has the disadvantage of significantly reducing the transparency of the film-like laminate when laminated on a transparent base material. I couldn't get enough of it. The inventors of the present invention have conducted intensive research on a method of extrusion laminating at an economically sufficient speed even when using polypropylene with a low M'1. Polypropylene modified by oxidative decomposition has significantly improved drawdown properties and M
The inventors discovered that high-speed extrusion lamination is possible even when using polypropylene with a low ml content, and this led to the completion of the present invention.

That is, in the present invention, at least one side of the membranous base material is closed, and the lutoflow index ratio (hereinafter abbreviated as MFIR) is 12.0.
This is a membrane-like laminate consisting of the following polypropylene films.

In addition, the M "IR" described in the present invention is 2 at 260qo.
It is expressed as the ratio of the MFI with a 16-key load and the MFI with a 32-key load at the same temperature, and is theoretically 6.65.
The following values cannot be taken. The membrane base material used in the present invention is not particularly limited as long as it can be laminated with a polypropylene film.

In general, various membrane-like substrates are already known, and these known ones may be selected and used as required. Examples of membrane-like substrates most preferably used include thermoplastic resin films or sheets, cellophane, paper, cloth, and aluminum foil. In particular, the membranous base material is a polypropylene film,
Particularly, biaxially oriented polypropylene film is preferred because it provides a film-like laminate with various excellent physical properties as described above. Of course, when the purpose of the obtained membranous laminate is a biaxially stretched polypropylene film, even if the polypropylene film described later is laminated on an unstretched polypropylene film as a membranous base material and then stretched biaxially, it cannot be uniaxially stretched. The object of the present invention can also be obtained by laminating a polypropylene film to be described later on the polypropylene film prepared above, and then performing second-axis stretching. In the present invention, the polypropylene film laminated on the membranous base material must have an MFIR of 1 sigma or less. If the MFIR exceeds the above-mentioned value, heat sealability, transparency, etc. will be insufficient, and when performing high-speed lamination, economically sufficient high-speed processability will not be obtained, which is not preferable. Generally, MFIR in the range of 9.0 to 11.5 is most widely and preferably used. Polypropylene films having an MFIR of 12 or less cannot be produced using ordinary commercially available polypropylene.

Generally commercially available polypropylene has an MFIR of 13
．． Many of them are in the range of 0 to 16.0, and even if a polypropylene film made of these polypropylenes is used as is, the object of the present invention cannot be obtained. In the present invention, the method for producing a polypropylene film having an M'IR of 1 or less is not limited, but typical methods will be explained below. That is, for example, the MFIR can be made 12 or less by melting and mixing polypropylene in the presence of an oxygen-containing gas such as air, oxidatively decomposing it, and modifying it. When polypropylene is oxidatively decomposed to lower its molecular weight, the MFIR becomes smaller, and by controlling the decomposition, modified polypropylene with an arbitrary MFIR of 12.0 or less can be obtained. High-speed processability when laminating polypropylene improves as MFIR decreases. Therefore, by using polypropylene modified to have an MFIR of 12.0 or less by oxidative decomposition of polypropylene with a low M circle 1, it is possible to impart high-speed processability that could not be achieved conventionally. The membranous laminate of the present invention can be obtained by laminating the M melon to a membranous base material using polypropylene with a thickness of less than 1 mm. Specifically, the means for oxidatively decomposing the polypropylene by mixing it in the presence of an oxygen-containing gas is to use an extruder or a bran mixer,
This can be easily done by blowing air into the material input or into the pen.

Oxidative decomposition is controlled by controlling the concentration of air blown into the resin, resin temperature,
This can be easily achieved by adjusting extrusion operating conditions such as residence time. For example, to adjust the air amount concentration, it is preferable to blow air into a part of the extruder hopper together with nitrogen gas so that a predetermined concentration is achieved, since this method is simple.

In addition to the above-mentioned oxidative decomposition using air, methods for decomposing polypropylene to reduce MF melon include adding decomposition aids such as organic peroxides, thermal decomposition, mechanical molecular cutting, etc. You can apply it accordingly. The polypropylene used in the present invention is not limited in any way, and commercially available polypropylene can be used without any restriction, but from the purpose of the present invention, it is preferable to use polypropylene with an M'1 of 0.5 to 30.0 g/1 h. .

In addition, the polypropylene in the present invention may be a propylene homopolymer; a random copolymer of propylene and other olefin monomers such as ethylene or butene-1; or a floc copolymer of propylene and the other olefin monomers, etc. You can select and use them according to your needs. In particular, when laminating an ethylene-propylene random copolymer film with an ethylene content of 1.0% (weight)% to 7.0% (weight)% as a polypropylene film on a membranous substrate, such as a polypropylene film, polypropylene is This is suitable because it can provide a film-like laminate with excellent low-temperature heat-sealing properties without impairing properties such as scratch resistance, transparency, blocking resistance, and hot tack properties.

In the present invention, antioxidants, thickening agents, antiblocking agents, antistatic agents, crystal nucleating agents, ultraviolet absorbers, etc. can be mixed within the range that does not impair the purpose of the present invention.

In the present invention, a membrane-like laminate obtained by extruding and laminating polypropylene with an MF of 12 or less, which is excellent in high-speed processability, onto a membrane-like substrate made of, for example, stretched polypropylene, has mechanical properties, heat sealability, Since it has excellent properties such as durability and transparency when laminated on a transparent base material, it can be suitably applied not only to the field of light packaging but also to the field of heavy packaging.

In order to obtain the film-like laminate of the present invention, it is generally preferable to apply an extrusion lamination method.

For the extrusion lamination method, a commonly used laminator may be used. In other words, any laminator may be used as long as it has a device that extrudes the molten resin into a film from an extruder die, presses the molten resin into the running film base material between a casting roll and a nip roll, and cools it. There are no limitations on the extrusion lamination method. The present invention will be explained below with reference to Examples, but the present invention is not limited to the following Examples. The following items in the examples were measured using the following method. 1 Melt flow index (M'1)A
Measurement was performed using a melt indexer manufactured by Takara Kogyo Co., Ltd. according to STMD-1238.

2 Haze Measured using a haze meter manufactured by Toyo Seiki Seisakusho Co., Ltd. according to JISK-6714.

3 Heat-sealing start temperature Using a hot plate heat sealer manufactured by Toyo Tester Kogyo Co., Ltd., a sample with heat-sealed portion dimensions of 5 ribs and 2 ribs in length obtained by pressing for 1 second with a load of 1 kg/c fin, Peeling speed 1
T-shaped peeling was performed at 0 blood/min and a peeling angle of 180° C., and the temperature at which a peel strength of 20 bits/arc was exhibited was taken as the heat sealing start temperature.

Therefore, the smaller this value is, the better the low-temperature heat sealability is. 4 Scratch Resistance Paste the sample with the laminate layer facing upwards in a box with a flat bottom with a length of 30 skins, a middle of 30 arcs, and a depth of 15 skins. Insert about 20 bullets into the box and make 30 cycles per minute, damaging the film attached to the hawk on the box.

The haze of the film after 3 minutes was measured and the magnification of haze increase was calculated.

Therefore, the smaller this value is, the better the scratch resistance is. 5 Hot tack property Pressure-bonded for 1 second using a hot plate heat sealer manufactured by Toyo Tester Kogyo Co., Ltd. under a load of 1.8k9/carp.The heat-sealed part was crimped for 1 second and the dimensions of the heat-sealed part were medium 15 skin and length 20. The length of the peeled heat-sealed portion was measured by applying 30 groups of loads.

When measuring while changing the heat sealing temperature, the peeling length at a certain temperature was the shortest, and the peeling length at this time was taken as the minimum peeling length. Therefore, the smaller this value is, the better the hot tack properties are. Examples 1 to 8 After a portion of the extruder hopper was completely replaced with nitrogen gas, various polypropylenes were melt-kneaded in the extruder while blowing a mixed gas of nitrogen gas and air with a predetermined oxygen concentration to produce modified polypropylene. Obtained.

Next, use a general laminator and set the die temperature to 270.
The modified polypropylene was laminated onto a predetermined laminating base material at a temperature of 0.degree. The conditions and results in this case are
Shown in the table. Also, Example 1 laminated to transparent Motomura
The haze values of the laminate films in the cases of ~3, 5, and 6 are also shown in Table 1. In this example, a lamination speed of 7 h/min or higher, which is sufficient for industrial implementation, was obtained, and the haze value of the laminated film when laminated onto a transparent film was good.

Comparative Examples 1 to 4 Comparative Examples 1 to 4 were conducted in the same manner as Examples 1 to 8, except that only nitrogen gas was blown during melt kneading using an extruder to obtain unmodified polypropylene.

The conditions and results at this time are shown in Table 2. In this comparative example, at a lamination speed of 5 h/min or more, surging occurred and a good laminated film could not be obtained.

Comparative Example 5 Low-density polyethylene (density 0.92 crab/ground, MF13. coat/1 skin in) was added to ethylene-propylene random copolymer.
Comparative Example 1 except that a mixture containing 12% by weight of ) was used.
It was laminated in the same manner as in 4.

The conditions and results are shown in Table 3. Lamination speed 8
The haze was 7.2%, which is more than twice as high as in the example.
Comparative Example 6 Lamination was carried out in the same manner as in Comparative Examples 1 to 4, using nitrogen gas containing 2% oxygen during melt-kneading using an extruder.

The results are as shown in Table 3.
The IR was 12.9 and the lamination speed was 4 h/min. Examples 9 to 16 Modified ethylene-propylene random copolymers were obtained using the same machine as Examples 1 to 8.

The copolymer was mixed with MFII. Using a commonly used laminator, laminate to a thickness of 0.15 mm at a die temperature of 270°C on a 1.5 mm thick unstretched polypropylene film made from 1 mm polypropylene. did. The thus obtained laminated film was stretched 5 times in the machine direction using a roll longitudinal stretching machine with a roll surface temperature of 150 qo, and further IM-stretched in the transverse direction using an oven-type machine stretching machine set at 170°C to determine the thickness. A laminated double-stretched polypropylene film of 33 layers was obtained. The heat sealing start temperature, haze, scratch resistance, and hot tack properties of the laminated Nito stretched polypropylene film were measured and shown in Table 4. The laminated double-stretched polypropylene film has excellent low-temperature heat-sealing properties, as well as excellent haze, scratch resistance, and hot-tack properties. Example 17 MFII. Example 1: The same modified ethylene-propylene random copolymer used in Example 14 was applied on a longitudinally stretched polypropylene film with a thickness of 30 r obtained by stretching 1 inch polypropylene 5 times in the longitudinal direction. 9-1
It was laminated to a thickness of 30 ridges in the same manner as in Step 6.

Then, 1N was drawn in an oven-type machine axial stretching machine set at 170°C.
A laminated biaxially stretched polypropylene film having a thickness of 33 peaks was obtained by horizontally stretching the film. Table 4 shows the properties of the laminated double-stretched polypropylene film. Example 18 Using the modified ethylene-propylene random copolymer used in Example 14, an unstretched polypropylene film having a thickness of 25 cm was prepared in a conventional manner.

The unstretched polypropylene film and a biaxially oriented polypropylene film having a thickness of 30 mm were dry laminated in a conventional manner to obtain a laminated biaxially oriented polypropylene film.
The results are shown in Table 4. Ship Ship Ship Minoru Funa Minoru■ Law

Claims (1)

[Claims] 1. A membranous laminate in which at least one side of the membranous base material is made of a polypropylene film having a melt flow index ratio of 12 or less. 2. A membranous laminate 3 according to claim 1, wherein the membranous base material is a polypropylene film. The polypropylene film has an ethylene content of 1.0% (weight) to 7.0% (by weight).
(wt)% ethylene-propylene random copolymer film according to claim 1.Membrane-like laminate according to claim 1, wherein the membranous base material is a biaxially stretched polypropylene film. thing