JP7010611B2 - Polypropylene-based uniaxially stretched film and film laminate - Google Patents

Description

The present invention relates to a polypropylene-based uniaxially stretched film and a film laminate, particularly a polypropylene-based uniaxially stretched film excellent in straight tearing, and relates to a film laminate using the film.

Currently, for packaging of various articles such as food, a film and an article are simultaneously supplied by an automatic wrapping machine, and filling, packaging, and sealing are continuously performed. One of the performances required for such a packaging film is the ease of opening the film constituting the package. Demand for stretched films with high straight-line cutability is attracting attention as one of the ease of opening. In this case, it is premised that sufficient strength is required to withstand the supply, processing, and distribution of the film, and a good appearance is also required.

Specifically, a laterally tearable biaxially stretched film composed of isotatic polypropylene, high-density polyethylene, and an ethylene / propylene copolymer has been proposed (see Patent Document 1 and the like). Further, a polyolefin uniaxially stretched film made of crystalline polypropylene, polyethylene, and atactic polypropylene has been proposed (see Patent Document 2 and the like). Further, a uniaxially stretched polyolefin film containing a propylene-based random copolymer and a low-density ethylene homopolymer has been proposed (see Patent Document 3 and the like).

As shown in each film disclosed in the exemplified patent document, a film formed by uniaxial stretching in the longitudinal direction or the transverse direction has a straight-line cut property along the stretching direction. Therefore, it is used as a film having good cutability utilizing this property. However, there are also the following problems. In the case of a uniaxially stretched film using a polypropylene-based random copolymer, the tear strength is lowered. In the case of a uniaxially stretched film using homopolypropylene, the straight-line cut property of the film is not good.

Therefore, there has been a demand for a uniaxially stretched film that can improve the straight-line cutability while maintaining the sufficient strength of the film itself and can satisfy the good appearance such as the transparency of the film.

Special Publication No. 56-21581 Japanese Unexamined Patent Publication No. 7-138423 Japanese Patent Publication No. 2013-542269

The present invention has been proposed in view of the above circumstances. In a polypropylene-based film that employs a uniaxially stretched manufacturing method, a straight-line cut that is a straight tear is achieved by improving the resin raw material that composes the film and its composition. Provided is a polypropylene uniaxially stretched film which has good properties and at the same time realizes good appearance of a film, and also provides a film laminate using the film.

That is, the first invention is a polypropylene-based film (10) having a draw ratio in the uniaxial direction of 3 to 10 times, wherein the polypropylene-based film (10) contains a polypropylene-based resin (A) by 55 to 98 weights. % And 45 to 2% by weight of the linear low-density polyethylene (B), and the polypropylene-based resin (A) is a propylene homopolymer, a propylene-ethylene random copolymer, or a propylene-ethylene-. At least one of a butene random copolymer and a propylene-ethylene block copolymer, and the linear low-density polyethylene (B) has a density of (b1): 0.860 to 0.955 g / cm ³ . , (B2): Melt flow rate (190 ° C., 2.16 kg load) is 3.5 to 4.0 g / 10 min, and (b3): Ethylene and α-olefin having 3 to 8 carbon atoms. The present invention relates to a polypropylene-based uniaxially stretched film, which is a random copolymer and is characterized in that the amount of deviation in straight-line cutability of the polypropylene-based film (10) measured based on a straight-line cutability test is 0.30 mm or less .

The second invention relates to the polypropylene-based uniaxially stretched film according to claim 1, wherein the haze of the polypropylene-based film measured in accordance with JIS K 7136 (2000) is 10% or less.

The third invention relates to the polypropylene-based uniaxially stretched film according to claim 1 or 2, wherein the polypropylene-based resin layer portion is provided on one side surface or both side surfaces of the polypropylene-based film.

The fourth invention relates to a film laminate characterized in that another film body is laminated on the outermost surface portion of the polypropylene-based uniaxially stretched film according to any one of claims 1 to 3.

According to the polypropylene-based uniaxially stretched film according to the first invention, it is a polypropylene-based film having a draw ratio in the uniaxial direction of 3 to 10 times, and the polypropylene-based film contains a polypropylene-based resin (A) of 55 to 98 weights. % And 45 to 2% by weight of the linear low-density polyethylene (B), and the polypropylene-based resin (A) is a propylene homopolymer, a propylene-ethylene random copolymer, or a propylene-ethylene-. At least one of a butene random copolymer and a propylene-ethylene block copolymer, and the linear low-density polyethylene (B) has a density of (b1): 0.860 to 0.955 g / cm ³ . , (B2): Melt flow rate (190 ° C., 2.16 kg load) is 3.5 to 4.0 g / 10 min, and (b3): Ethethylene and α-olefin having 3 to 8 carbon atoms. Since it is a random copolymer and the amount of deviation in straight-cutting property of the polypropylene-based film measured based on the straight-line cutting property test is 0.30 mm or less, straight tearing in the polypropylene-based film adopting the uniaxially stretched manufacturing method. It is possible to obtain a polypropylene uniaxially stretched film that realizes good straight-line cutability and good appearance of the film.

According to the polypropylene-based uniaxially stretched film according to the second invention, in the first invention, the haze of the polypropylene-based film measured in accordance with JIS K 7136 (2000) is 10% or less, so that the haze is transparent and beautiful. The film is finished.

According to the polypropylene-based uniaxially stretched film according to the third invention, in the first invention, since the propylene-based resin layer portion is provided on one side surface or both side surfaces of the polypropylene-based film, the function of the polypropylene-based uniaxially stretched film is improved. Be done.

According to the film laminate according to the fourth invention, since the other film body is laminated on the outermost surface portion of the polypropylene-based uniaxially stretched film according to any one of claims 1 to 3, even after the lamination. , It is possible to obtain a film laminate having good straight-line cutting property, which is a straight tear.

It is a schematic cross-sectional schematic diagram of the polypropylene-based uniaxially stretched film of 1st Embodiment. It is a schematic cross-sectional schematic diagram of the polypropylene-based uniaxially stretched film of the 2nd and 3rd embodiments. It is schematic cross-sectional schematic diagram of the film laminated body of 1st and 2nd Embodiment. It is schematic cross-sectional schematic diagram of the film laminated body of 3rd and 4th Embodiment. It is a schematic diagram which shows the straight-ahead cut test.

FIG. 1 shows a schematic cross-sectional view of the polypropylene-based film 10 of the first embodiment of the polypropylene-based uniaxially stretched film 1. As shown in the figure, it is a single layer. For convenience, each surface of the film will be referred to as a first surface portion 11 and a second surface portion 12 in the following description.

During the uniaxially stretched film formation, the molten resin forming the polypropylene film 10 is discharged from a T-die or the like and is formed through inter-roll stretching or tenter stretching. Therefore, the film of the present invention is a uniaxially stretched film in consideration of good tearing in one direction, and in particular, is a substantially longitudinally or laterally uniaxially stretched film. At the time of manufacturing the polypropylene film 10, the draw ratio (stretching between rolls, tenter stretching) is 3 to 10 times. When the draw ratio is less than 3 times, straight tearing (straight tearing property, straight cutting property) derived from uniaxial stretching is unlikely to occur. In addition, poor appearance is likely to occur due to insufficient stretching. When the stretching ratio exceeds 10 times, the amount of stretching is large, so that the film is easily broken during stretching and poor film formation is likely to occur. Therefore, the draw ratio is 3 to 10 times in consideration of ensuring beautiful transparency. However, stretching in other directions may be included as a force majeure during film formation. The constituent resins of each layer will be described in order.

Further, the polypropylene-based resin (A) is selected from at least one of a propylene homopolymer, a propylene-ethylene random copolymer, a propylene-ethylene-butene random copolymer, and a propylene-ethylene block copolymer. .. Of course, the resin may be selected as one type or a mixture of two or more types. As described above, the polypropylene-based resin (A) can be selected from a wide range of polypropylene-based resins suitable for ensuring the strength of the polypropylene-based film 10.

The polyethylene blended in the polypropylene-based film 10 of the present invention is limited to the linear low-density polyethylene (B) as described above. This is because the transparency of both the low-density polyethylene and the high-density polyethylene is lowered from the examples described later. Further, this is because the low-density polyethylene has a tear defect.

Further, the linear low density polyethylene (B) satisfies the following relationships (b1), (b2), and (b3). In the first (b1), the density of the linear low density polyethylene (B) is 0.860 to 0.955 g / cm ³ . When the density of the linear low-density polyethylene (B) is lower than this range, blocking is likely to occur due to a decrease in the melting point. On the contrary, the transparency of the film is inferior in the linear low-density polyethylene (B) having a density higher than that range. It is an increase in haze in the examples described later.

In the second (b2), the melt flow rate (MFR) (190 ° C., 2.16 kg load) of the linear low density polyethylene (B) is in the range of 0.1 to 20 g / 10 min. This range is a range required for the convenience of film formation. When the melt flow rate decreases, it leads to poor appearance and deterioration of moldability. Moreover, if it becomes too high, it leads to blocking and deterioration of moldability. Therefore, the above range is preferable, and the range of 1 to 5 g / 10 min is more preferable.

As the third (b3), the linear low-density polyethylene (B) is a random copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms. The type of α-olefin in the linear low density polyethylene (B) depends on the alkene that can be introduced. For example, 1-butene, 1-hexene, 4-methyl-1-pentene and the like, and a plurality of types may be used. If the carbon number of the α-olefin is less than 3, it does not make sense to introduce the α-olefin. Further, it is almost difficult to obtain a resin containing an α-olefin having 9 or more carbon atoms. Therefore, considering the practically available and appropriate performance, the appropriate range of carbon number of α-olefin is 3 to 8.

The good appearance of the polypropylene film 10 is the transparency of the film. Therefore, when determining transparency, it is possible to evaluate by the level of the haze value. Therefore, the haze value of the polypropylene film 10 measured according to JIS K 7136 (2000) is used for the evaluation. In the polypropylene-based film 10, when the haze value exceeds 10%, the transparency of the film itself is lost and the appearance is distant from a beautiful appearance. When the haze value is 10% or less, the film becomes transparent and beautiful. This point can be judged from the evaluation of the examples described later.

In addition, another propylene-based resin layer portion 20 (30) is provided on one side surface or both side surfaces of the polypropylene-based film 10. FIG. 2A is a schematic cross-sectional view of the polypropylene-based uniaxially stretched film 2, and the propylene-based resin layer portion 20 is provided on the first surface portion 11 side of the polypropylene-based film 10. FIG. 2B is a schematic cross-sectional view of the polypropylene-based uniaxially stretched film 3, wherein the propylene-based resin layer portion 20 is provided on the first surface portion 11 side of the polypropylene-based film 10, and the propylene-based resin is provided on the second surface portion 12 side. A layer 30 is provided.

For example, the propylene-based resin layer portion 20 is a sealant layer in the film, and the propylene-based resin layer portion 30 is a surface layer. In this case, the heat sealing performance is enhanced by providing the sealant layer. In addition, by providing the surface layer, corona treatment or the like is applied, and the printing performance of the film surface is also improved. Therefore, since another type of propylene-based resin layer portion is provided on one side surface or both side surfaces of the polypropylene-based film 10, the functions of the polypropylene-based uniaxially stretched films 2 and 3 can be improved.

When forming the propylene-based resin layer portion 20 (30), the raw material resin corresponding to each layer is melted and discharged from a T-die or the like so as to have a predetermined thickness ratio. After that, it is stretched between rolls in a uniaxial direction (longitudinal uniaxial direction) by a stretching roll or the like. Alternatively, it is stretched in the horizontal uniaxial direction through a tenter or the like. The thickness ratio of the polypropylene-based film 10 and the propylene-based resin layer portion 20 (30) is relatively free, and is in the range of 1:15 to 15: 1 for the polypropylene-based film 10 and the propylene-based resin layer portion 20. Further, even in a structure in which the polypropylene-based film 10 is sandwiched between the propylene-based resin layer portions 20 and 30, the ratio is 1: 1: 1 to 1: 15: 1.

The composition of the resin of the propylene-based resin layer portion 20 (30) is propylene-based such as a propylene homopolymer, a propylene-ethylene random copolymer, a propylene-ethylene-butene random copolymer, or a propylene-ethylene block copolymer. Selected from resins. Further, an elastomer component such as an ethylene-based elastomer, a propylene-based elastomer, or a butene-based elastomer can be blended. When selecting the resin for the propylene-based resin layer portion 20 (30), compatibility with the polypropylene-based film 10 is taken into consideration.

Appropriate additives are added to the above-mentioned resin, if necessary, to the polypropylene-based uniaxially stretched film 1 (polypropylene-based film 10) and the propylene-based resin layer portions 20 (30) of the polypropylene-based uniaxially stretched films 2 and 3. For example, various antistatic agents include aliphatic amine compounds such as lauryldiethanolamine, myristyldiethanolamine and oleyldiethanolamine, aliphatic amide compounds such as lauryldiethanolamide, myristyldiethanolamide and oleyldiethanolamide, and polyhydric alcohols. Further, various additives such as an anti-blocking agent, a lubricant, a heat stabilizer, an antioxidant, a light stabilizer, a crystal nucleating agent, and an ultraviolet absorber are also added in a required amount.

Schematic schematic cross-sectional views of FIGS. 3 and 4 show film laminates 4, 5, 6, and 7. In the illustrated film laminate, another known film body 40 is formed on the outermost surfaces of the polypropylene-based uniaxially stretched film 1 (polypropylene-based film 10) and the polypropylene-based uniaxially stretched films 2 and 3 disclosed in FIGS. 1 and 2. It is laminated and laminated. When laminating each film and the film body 40, the laminating method is not limited, and a known method such as dry laminating, extruded laminating, or hot melt laminating is adopted depending on the purpose.

For the film body 40, a film of a general resin type is used. For example, a polypropylene film, a polyester film such as polyethylene terephthalate (PET) film or polybutylene terephthalate, a polyamide film (nylon film) and the like can be mentioned. 3 and 4 are examples in which dry-laminate adhesion is adopted, and are attached via the laminate adhesive 45.

The film laminate 4 of FIG. 3A is an example in which the film body 40 is laminated on one side surface of the polypropylene-based uniaxially stretched film 1 (polypropylene-based film 10). The film laminate 5 of FIG. 3B is an example in which the film body 40 is directly laminated on the polypropylene film 10 side in the polypropylene-based uniaxially stretched film 2. The film laminate 6 in FIG. 4A is an example in which the film body 40 is directly laminated on the propylene resin layer portion 20 side of the polypropylene-based uniaxially stretched film 2. The film laminate 7 of FIG. 4B is an example in which the film body 40 is directly laminated on the propylene resin layer portion 30 side of the polypropylene-based uniaxially stretched film 3. Of course, it is naturally possible to adopt a laminated structure other than the one shown in the figure. The structure of the finally completed film laminate can be freely designed according to the use, purpose, etc. of the film laminate.

Polypropylene-based uniaxially stretched films 1, 2, 3 and film laminates 4, 5, 6, 7 are mainly used as packaging materials. For example, the formation of bag-shaped objects such as three-way stickers and pillow packaging. In particular, since it has a good straight-line cut property, which is a straight tear, the bag-shaped object can be opened with a slight force. As a result, it becomes easy to open the bag-shaped object containing small articles and the like.

[Preparation of polypropylene-based uniaxially stretched film]
Examples 1 to 6 and Comparative Examples 1 to 5 are examples (single layer) corresponding to the polypropylene-based uniaxially stretched film 1 of the first embodiment disclosed in FIG. Examples 7 to 9 are examples (two layers) corresponding to the polypropylene-based uniaxially stretched film 2 of the second embodiment disclosed in FIG. 2.

For Examples 1 to 6 and Comparative Examples 1 to 5, the raw material resin was melted and kneaded based on the resin composition and its ratio shown in Tables 1 to 3 below, and co-extruded T-die film. A sheet was prepared using a molding machine, and a film was formed by stretching it vertically and uniaxially in the winding direction (MD) by a stretching machine between rolls.

In Examples 7 to 9, the polypropylene-based film of the base material portion and the raw material resin of the propylene-based resin layer portion arranged on one side surface thereof are based on the resin composition and the ratio of each layer shown in Table 3 below. The resin used as a raw material was melted and kneaded to prepare a sheet using a co-extruded T-die film forming machine, and a film was formed by stretching it vertically and uniaxially in the winding direction (MD) with an inter-roll stretching machine.

The stretching ratios of Examples and Comparative Examples were set to 3 to 7 times by adjusting the stretching machine between rolls.

[Raw materials used]
The polypropylene-based uniaxially stretched films of the respective examples and comparative examples, and the raw material resins of the propylene-based resin layer portion arranged on one side surface of the uniaxially stretched film include the following polypropylene-based resins (resins 01 to 03) and polyethylene resins. (Resin 11 to 15) was selected and used. The melt flow rate is expressed as MFR (same below).

<Polypropylene resin>
(Resin 01) Propylene homopolymer: Made by Japan Polypropylene Corporation, trade name "Novatec FY6", MFR (230 ° C, 2.16 kg load) 2.5 g / 10 min, density 0.90 g / cm ³
(Resin 02) Propylene-ethylene random copolymer: manufactured by Japan Polypropylene Corporation, trade name "Wintech WFW4", MFR (230 ° C, 2.16 kg load) 7.0 g / 10 min, density 0.9 g / cm ³
(Resin 03) Propylene-ethylene block copolymer: manufactured by Japan Polypropylene Corporation, trade name "BC5FA", MFR (230 ° C, 2.16 kg load) 3.5 g / 10 min

<Polyethylene resin>
(Resin 11) Linear low-density polyethylene: Made by Japan Polyethylene Corporation, trade name "KF380", MFR (190 ° C, 2.16 kg load) 4.0 g / 10 min, density 0.918 g / cm ³
(Resin 12) Linear low-density polyethylene: Made by Japan Polyethylene Corporation, trade name "Kernel KS340T", MFR (190 ° C, 2.16 kg load) 3.5 g / 10 min, density 0.880 g / cm ³
(Resin 13) Linear low-density polyethylene: manufactured by Ube-Maruzen Polyethylene Co., Ltd., trade name "Umerit 4540F", MFR (190 ° C, 2.16 kg load) 4.0 g / 10 min, density 0.944 g / cm ³
(Resin 14) Low-density polyethylene: manufactured by Ube-Maruzen Polyethylene Co., Ltd., trade name "F222", MFR (190 ° C, 2.16 kg load) 2.0 g / 10 min, density 0.922 g / cm ³
(Resin 15) High-density polyethylene: manufactured by Keiyo Polyethylene Co., Ltd., trade name "M8500", MFR (190 ° C, 2.16 kg load) 5.0 g / 10 min, density 0.962 g / cm ³

The following raw materials were also used as other ingredients.
As the anti-blocking agent, powdered synthetic silica (manufactured by Fuji Silysia Chemical Ltd., trade name "Silysia 550") was used. The anti-blocking agent is not described in the table because it is a very small amount.

[Measurement of physical properties]
<Thickness and thickness ratio of each layer>
The thicknesses of the polypropylene-based uniaxially stretched films of Examples and Comparative Examples were measured according to JIS K 7130 (1999), respectively. The layer thickness of the polypropylene-based uniaxially stretched film of Examples 7 to 9 is adjusted by the discharge amount from the T die, and the thickness obtained by measuring the stretched film is proportionally divided according to the set ratio (layer ratio). Asked.

<Haze>
The haze was measured in accordance with JIS K 7136 (2000), and a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., NDH-5000) was used to measure all Examples and Comparative Examples (unit%). In the evaluation of the haze value of each film, an example of a haze value of 10% or less is evaluated as "A" as a good product having sufficient transparency, and an example of a haze value of more than 10% is defective as inferior in transparency. It was evaluated as "F".

<Straight cut property>
With respect to the polypropylene-based uniaxially stretched films of Examples and Comparative Examples, each example was cut out into a rectangular shape of 200 mm × 100 mm having the flow direction (MD) of each film as the long side and the width direction (TD) as the short side. The test film 100 corresponding to the above (see FIG. 5A). Next, the super straight cutter SSK-1000-D manufactured by Dumbbell Co., Ltd. was connected to the SD type lever type sample cutter SDL-200 manufactured by the same company. Then, a notch of 10 mm in width and 40 mm is made in the flow direction (MD) from the short side toward the center of the test film on one short side 102 of each test film, and the long side 102 is long. The tongue piece 105 was formed. Reference numeral 101 is a long side of the test film 100.

After forming the tongue piece portion 105 on the test film 100, the mark L1 of the tear start position was attached to the base of the tongue piece portion 105. Align the long side 101 of the test film 100 with the longitudinal direction of the test table (not shown) of the friction tester TR-2 manufactured by Toyo Seiki Seisakusho, and place the tongue piece 105 on the right hand side of the test table. I put it. The four corners of the test film 100 were fixed to the test table with tape or the like.

The tongue piece 105 was rolled up and folded back in the opposite direction, attached to the sliding piece 110 of the friction tester, and the sliding piece 110 was connected to a wire (not shown) attached to the friction tester (FIG. 5 (b)). reference). The test table of the friction tester was moved 200 mm to the right of the paper surface at a moving speed of 1500 mm / min to pull the tongue piece 105, and the test film was torn.

After the tearing was completed, the mark L2 at the end position of the tearing was marked, and the width W2 of the tongue piece portion 105 at the same position was measured. The width of the tongue piece portion 105 at the tear start position L1 and the tear end position L2 was measured by the ABS Digimatic Capari CD-15AXWW manufactured by Mitutoyo Co., Ltd. for the notch interval. Therefore, the amount of deviation (G) (mm) was obtained from the change in width before and after tearing (see FIG. 5 (c)).

The deviation amount (G) is the difference between the “width W2 of the tear end position L2” and the “width W1 of the tear start position L1” and is used as an absolute value evaluation. That is, "deviation amount (G) (mm) = | W2-W1 |". If the test film has a deviation amount (G) of 2 mm or less, it can be torn almost straight, and the straight-line cutability was evaluated as "A". A test film having a displacement amount (G) exceeding 2 mm or having difficulty in tearing itself was given a defect rating of “F”.

Tables 1 to 3 are the results of polypropylene-based uniaxially stretched films of Examples 1 to 9 and Comparative Examples 1 to 5 (Table 3 includes a propylene-based resin layer portion). In the table, in order from the top, the type of the raw material resin of the polypropylene film (10) and its blending ratio (% by weight), the type of the raw material resin of the propylene based resin layer portion (20) and its blending ratio (% by weight), and the stretching ratio ( Double), thickness (μm), layer ratio of polypropylene film (10) and propylene resin layer (20) thickness (Table 3 only), haze (%), haze evaluation (2 steps), straight cut The amount of deviation (mm) and the evaluation of straight-line cutability (2 steps) are shown.

[Results / Discussion of Fabrication of Polypropylene-based Uniaxial Stretched Film]
Regarding the evaluation of all the examples, there was no evaluation of "F" and good performance was shown. In addition, no defects in the appearance of the film were observed, and the finish was good. The stretching ratio was 3 to 7 times in the uniaxial direction (vertical uniaxial stretching direction in this embodiment). The condition is in a suitable range in consideration of the following physical characteristics and performance. Therefore, the draw ratio in the uniaxial direction in film production can be derived to be 3 to 10 times, more preferably 3 to 7 times.

From the results of producing the polypropylene-based uniaxially stretched film, the straight-line cutability of Comparative Examples 1 to 3 in which the polyethylene resin was not contained in the polypropylene-based uniaxially stretched film (polypropylene-based film) was significantly reduced. Further, with respect to the polyethylene resin, the straight-line cut property was lowered (Comparative Example 4) and the haze was significantly deteriorated (Comparative Example 5) when the composition other than the linear low-density polyethylene resin was used. Therefore, when producing a polypropylene-based uniaxially stretched film, a polyethylene resin is indispensable and a linear low-density polyethylene resin is best blended as in the examples.

Next, looking at the blending ratio (% by weight) of the polypropylene-based resin and the linear low-density polyethylene resin in the polypropylene-based film, it is clear that the performance deteriorates without blending the linear low-density polyethylene resin. When it reached 5% by weight from the second example, the haze and straight-line cutability improved. The composition of the linear low-density polyethylene resin of Example 4 is 40% by weight. Therefore, considering the satisfaction of haze and straight-line cutability and the mutual resin blending ratio, polypropylene-based resin is 55 to 98% by weight, preferably 60 to 95% by weight, and linear low-density polyethylene is 45 to 2% by weight. Percentage, preferably 40 to 5% by weight, is suitable.

Focusing on the polypropylene film, the density of the resin 11 to the resin 13 of the linear low-density polyethylene resin is in the range of 0.880 to 0.944 g / cm ³ , and all the examples show good results. rice field. Therefore, the density of the preferable linear low-density polyethylene resin can be in the range of 0.860 to 0.955 g / cm ³ .

The melt flow rate (190 ° C., 2.16 kg load) of the resins 11 to 13 was also in the range of 3.5 to 4.0 g / 10 min, and all the examples showed good results. Therefore, in consideration of a reasonable range, it was set to 0.1 to 20 g / 10 min.

Since the resins 11 to 13 used are random copolymers of ethylene and α-olefins having 3 to 8 carbon atoms, it was confirmed that the same structure is preferable.

Even in the polypropylene-based uniaxially stretched film having a two-layer structure including the propylene-based resin layer portion of Examples 7, 8 and 9, since it was within the range satisfying the provisions of Examples, both haze and straight-line cutability were good. there were.

From the above results, the polypropylene-based uniaxially stretched films of Examples 1 to 9 are films that exhibit low haze (transparency) and good straight-line cutability, which is a straight tear, as long as the above-mentioned resin composition and composition are satisfied. .. Therefore, the contents have a good appearance and are extremely convenient as a packaging material that can be easily opened.

[Preparation of film laminate]
The performance of the polypropylene-based uniaxially stretched film was confirmed from the history so far. Therefore, the following two types of film bodies were laminated by dry laminating on the outermost surfaces of the polypropylene-based uniaxially stretched films of Examples 3 and 8 and Comparative Example 3 to prepare a film laminate.
(Film body 1) Biaxially stretched polypropylene film (manufactured by Futamura Chemical Co., Ltd., trade name "FOR", thickness 20 μm)
(Film body 2) Unstretched polypropylene film (manufactured by Futamura Chemical Co., Ltd., trade name "FHK2", thickness 30 μm)

The adhesive (dry laminate adhesive) for laminating the films is 17.2% by weight of the main agent (manufactured by Toyo Morton Co., Ltd., TM-329) and 17.2% by weight of the curing agent (manufactured by the same company, CAT-8B). , And 65.6% by weight of ethyl acetate were mixed and prepared. The adhesive (solid content) prepared above was applied to the film body 1 or the film body 2 at a coating amount of 4 g / m ² , and dried at 80 ° C. for 30 seconds. Subsequently, the polypropylene-based uniaxially stretched films (surfaces excluding the propylene-based resin layer portion) of each Example and Comparative Example are bonded to the coated film body 1 or film body 2 to form a film laminate (Example 3). -2, 3-3, 8-2, 8-3, Comparative Example 3-2, 3-3) were obtained.

For each film laminate, "straight cutability" was evaluated based on the same method as described above. Table 4 shows, in order, the type of polypropylene-based uniaxially stretched film, film body 1 or film body 2 used (indicated by the column with a circle), the amount of deviation in straight-line cutability (mm), and the evaluation of straight-line cutability (2 levels). show.

[Results / Discussion of Fabrication of Film Laminate]
In the example using the polypropylene-based uniaxially stretched film of the example, even after processing into a film laminate, the amount of deviation in the straight-line cut property was small, and good straight-line cut property could be confirmed. This point is clear from the comparison with Comparative Examples 3-2 and 3-3. Since the polypropylene-based uniaxially stretched film (single layer or two layers) itself has good straight-line cutability, it was also confirmed that even if another film body is laminated, the straight-line cut property of the entire laminated body can be guaranteed. .. Therefore, a film laminate using a polypropylene-based uniaxially stretched film satisfying the above-mentioned resin composition and composition can continue to be torn straight. Therefore, the convenience as a material film for packaging purposes is enhanced.

The polypropylene-based uniaxially stretched film of the present invention can realize good straight-cutting property, which is a straight tear, and good appearance of a transparent film by improving the resin composition in its composition, and is used for packaging materials and the like. Will be more suitable. In addition, the film of the present invention can be developed into a film laminate or a bag-shaped material, so that the range of applications is widened.

1,2,3 Polypropylene-based uniaxially stretched film 4,5,6,7 Film laminate 10 Polypropylene-based film 11 First side part 12 Second side part 20,30 Propene-based resin layer part 40 Film body 45 Laminate adhesive

Claims (4)

A polypropylene-based film (10) having a uniaxial stretching ratio of 3 to 10 times.
The polypropylene-based film (10) has a composition of 55 to 98% by weight of the polypropylene-based resin (A) and 45 to 2% by weight of the linear low-density polyethylene (B).
The polypropylene-based resin (A) is at least one of a propylene homopolymer, a propylene-ethylene random copolymer, a propylene-ethylene-butene random copolymer, and a propylene-ethylene block copolymer.
The linear low-density polyethylene (B) is
(B1): The density is 0.860 to 0.955 g / cm ³ .
(B2): The melt flow rate (190 ° C., 2.16 kg load) is set to 3.5 to 4.0 g / 10 min, and
(B3): A random copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms.
The straight-line cutability deviation amount of the polypropylene-based film (10) measured based on the following straight-line cutability test is 0.30 mm or less.
A polypropylene-based uniaxially stretched film characterized by this.
Straight-line cutability test: The test film is cut out in a rectangular shape of 200 mm × 100 mm with the flow direction (MD) as the long side and the width direction (TD) as the short side during film formation. Make a 10 mm wide and 40 mm notch in the flow direction (MD) from the short side toward the center to form a long tongue piece on one short side, roll the tongue piece and fold it in the opposite direction. Using a friction tester, pull the tongue piece by 200 mm at a moving speed of 1500 mm / min to tear the test film, measure the width of the tongue piece at the tear start position and the tear end position, and measure the width of the tear end position and the tear. The difference in the width of the start position is calculated as the straight-line cutability deviation amount (mm) by the absolute value evaluation. The polypropylene-based uniaxially stretched film according to claim 1, wherein the haze of the polypropylene-based film (10) measured in accordance with JIS K 7136 (2000) is 10% or less. The polypropylene-based uniaxially stretched film according to claim 1 or 2, wherein the polypropylene-based resin layer portion is provided on one side surface or both side surfaces of the polypropylene-based film (10). A film laminate characterized in that another film body is laminated on the outermost surface portion of the polypropylene-based uniaxially stretched film according to any one of claims 1 to 3.

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