JP6791728B2 - Polypropylene-based stretched sealant film and film laminate using this - Google Patents

Description

The present invention relates to a polypropylene-based stretched sealant film and a film laminate using the same, and more particularly to a polypropylene-based stretched sealant film having excellent automatic packaging suitability, easy tearability, and strength, and a film laminate using the same.

Currently, in the packaging of articles, a film and an article are supplied by an automatic wrapping machine, and filling, packaging, and sealing are continuously performed. The performance required for such a packaging film is sufficient durability and strength during the supply and processing of the film, as well as during distribution. In particular, the film is processed into the form of a packaging bag and distributed. When this packaging bag is used, it is necessary to have an appropriate film strength called rupture resistance. Generally, when improving the bag-breaking resistance, a base film such as a stretched polypropylene film, a stretched polyester film, and a stretched polyamide film is laminated with a non-stretched sealant film. Further, in the case of imparting bag-break resistance, a polypropylene-based film in which a thermoplastic elastomer is added to a non-stretched sealant film is disclosed (see Patent Document 1). However, there is a problem that the tearability is lowered.

A stretched sealant film has been proposed as a technique for imparting tearability to a sealant film, and an intermediate adhesive layer made of a graft-modified product of an ethylene-vinyl acetate copolymer or the like is provided between a base material layer and a seal layer. As a result, a heat-sealable laminated stretched polypropylene film with improved heat-sealing strength is disclosed (see Patent Document 2). Further, an intermediate layer containing a propylene resin and an ethylene resin is formed between the upper layer containing the propylene resin and the seal layer containing the low density polyethylene and / or the linear low density polyethylene. A multilayer stretched film having improved heat-sealing strength by being provided is disclosed (see Patent Document 3).

Although the films disclosed in Patent Documents 2 and 3 all have high heat-sealing strength, they have not reached a satisfactory level in terms of bag breaking resistance. Therefore, as a packaging material for retorts with improved bag-break resistance, a longitudinally uniaxially stretched film having a heat-sealing layer containing an ethylene-propylene impact copolymer and a metallocene-catalyzed propylene-butene elastomer has been disclosed (Patent Documents). 4). However, even with the film of Patent Document 4, the bag-breaking resistance of the laminated body when laminated with another base film has not yet reached a satisfactory level.

In a bag using a laminated film (laminated film) in which a sealant film and another base film are laminated, a large number of bag breakages occur near the fusion site due to heat sealing between the sealant films. That is, since various stresses are concentrated in the vicinity of the fused portion of the heat seal, the portion having low strength leads to fracture. In the laminated film, the sealing strength, interlayer strength, or laminating strength of the stretched sealant film is weak, and the bag tends to break more easily than the non-stretched sealant film. From this, it has been required to improve the bag breaking resistance of the stretched sealant film.

Japanese Unexamined Patent Publication No. 7-309985 Japanese Patent No. 3934181 JP-A-2002-347192 Japanese Patent No. 541 1935

The present invention has been proposed in view of the above circumstances, and by improving the resin raw material constituting the polypropylene-based stretched sealant film and its composition, polypropylene-based stretched film having excellent automatic packaging suitability, easy tearability, and strength. A sealant film and a film laminate using the sealant film are provided.

That is, the invention of claim 1 is a polypropylene-based stretched sealant film comprising a base material layer and a heat-sealable sealant layer on one side of the base material layer, and having a uniaxial stretching ratio of 3 to 10 times. The base material layer contains 50 to 85% by weight of a polypropylene-based resin and 15 to 50% by weight of a thermoplastic elastomer, and the polypropylene-based resin contains a propylene homopolymer and a propylene-ethylene random copolymer. The thermoplastic elastomer contains either a coalescence, a propylene-ethylene-butene random copolymer, or a propylene-ethylene block copolymer, and the thermoplastic elastomer is an elastomer resin satisfying the following relationships (b1) to (b3). Containing (b1): the density of the elastomer resin is 0.860 to 0.895 g / cm ³ , and (b2): the melt flow rate (190 ° C., 2.16 kg load) of the elastomer resin is 0.5. 10 g / 10 min, (b3): The elastomer resin is a random copolymer of either ethylene, propylene, or 1-butene and α-olefin having 2 to 8 carbon atoms (excluding monomers of the same type). Is either an olefin-based elastomer resin or a styrene-based elastomer resin having a styrene content of 30% by weight or less, and the sealant layer is a propylene homopolymer, a propylene-ethylene random copolymer, or propylene-ethylene. The present invention relates to a polypropylene-based stretched sealant film, which comprises either a-butene random copolymer or a propylene-ethylene block copolymer.

The invention of claim 2 relates to a film laminate characterized in that the substrate layer of the polypropylene-based stretched sealant film according to claim 1 is provided with a film to be laminated.

The invention of claim 3 relates to the film laminate according to claim 2, wherein the film to be laminated is provided with a metal layer portion.

The film according to claim 4, wherein the breaking energy of the polypropylene-based stretched sealant film in the film laminate is 0.1 J / 1.5 cm ² or more in the following measurement (I). It relates to a laminated body.

In the measurement (I), the heat-sealed portions are heat-sealed so that the sealant layer sides of the film laminate can be peeled off in the winding direction, and the heat-sealed portions are arranged in the center, and the non-heat-sealed portions are arranged at both ends thereof. In addition to forming an inverted Y-shape when viewed from the side, cut into a test piece according to the 3 form described in the JIS K 7160 (1996) standard while leaving the heat seal part in the center, and the gripping tool described in the same standard. One end side of the test piece is fixed by the above, and the other end side is fixed by a 15 g cross head and placed on the cross head support base. After raising the striker to 150 ° where the potential energy is 2J, the striker is swung down, and the striker collides with the crosshead having one end side of the test piece fixed to break the test piece to break the crosshead. Read the angle of the striker at the time of flipping and swinging up. Then, the fracture energy (D) was calculated based on the correction formula (fi) by the simple correction method based on the potential energy described in JIS K 7110 (1999) and 711-1 (2012). Here, the plastic deformation and kinetic energy correction of the crosshead were calculated by the correction formula described in Annex C of JIS K 7160 (1996).
WR: Moment around the axis of rotation of the striker (Nm)
α: Striker lifting angle (°)
α': Striker swing-up angle (°) when the test piece is not attached
β: Swing-up angle (°) of striker when the test piece is broken

According to the polypropylene-based stretched sealant film according to the invention of claim 1, a polypropylene having a base material layer and a heat-sealing sealant layer on one side of the base material layer, and having a uniaxial stretching ratio of 3 to 10 times. A stretched sealant film, the base material layer contains 50 to 85% by weight of a polypropylene resin and 15 to 50% by weight of a thermoplastic elastomer, and the polypropylene resin is a propylene homopolymer. The thermoplastic elastomer contains any of a propylene-ethylene random copolymer, a propylene-ethylene-butene random copolymer, or a propylene-ethylene block copolymer, and the thermoplastic elastomer has the following relationships (b1) to (b3). (B1): The density of the elastomer resin is 0.860 to 0.895 g / cm ³ , and (b2): Melt flow rate of the elastomer resin (190 ° C., 2.16 kg). (Load) is 0.5 to 10 g / 10 min, and (b3): the elastomer resin is α-olefin having 2 to 8 carbon atoms (excluding the same type of monomer) with either ethylene, propylene, or 1-butene. It is either an olefin-based elastomer resin which is a random copolymer of propylene or a styrene-based elastomer resin having a styrene content of 30% by weight or less, and the sealant layer is a polypropylene homopolymer or a polypropylene-ethylene random compound. Since it contains either a polymer, a propylene-ethylene-butene random copolymer, or a propylene-ethylene block copolymer, a polypropylene-based stretched sealant film having excellent automatic packaging suitability, easy tearability, and strength can be obtained. Obtainable.

According to the film laminate according to the invention of claim 2, since the substrate layer of the polypropylene-based stretched sealant film according to claim 1 is provided with a film to be laminated, it has both easy tearability and rupture resistance. It can be effectively used as various materials.

According to the film laminate according to the invention of claim 3, in the invention of claim 2, since the metal layer portion is provided in the film to be laminated, the barrier property and the light-shielding property of the finished film are enhanced.

According to the film laminate according to the invention of claim 4, in the invention of claim 2 or 3, the breaking energy of the polypropylene-based stretched sealant film in the film laminate is 0.1 J / 1.5 cm ² or more. , Durability and bag resistance are improved, and the use of materials is expanded.

It is a schematic cross-sectional schematic diagram of the polypropylene-based stretched sealant film of this invention. It is a schematic cross-sectional schematic diagram of the film laminate of 1st Embodiment. It is schematic cross-sectional schematic diagram of the film laminate of 2nd Embodiment. It is 1st schematic diagram which shows the state at the time of measurement of the test piece of a film laminate. It is a 2nd schematic diagram which shows the state at the time of measurement of the test piece of a film laminate. It is the enlarged cross-sectional schematic diagram of the test piece under the load.

FIG. 1 shows a schematic cross-sectional view of the polypropylene-based stretched sealant film 1. The base material layer 10 which is the main body of the sealant film 1 and the sealant layer 20 which can be heat-sealed are provided on one side (first surface 11) of the base material layer 10. The polypropylene-based stretched sealant film 1 is formed by stretching 3 to 10 times in the substantially uniaxial direction. Reference numeral 12 is a second surface of the base material layer 10.

When the polypropylene-based stretched sealant film 1 is formed, 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 in the uniaxial direction. The thickness ratio of the base material layer 10 and the sealant layer 20 is not strict, and is generally in an appropriate range of 1:15 to 15: 1.

Generally, there are two stretching directions of the resin film, one in the winding direction (MD) and the other in the width direction (TD). Film formation with stretching in either one direction is uniaxial stretching, and film formation with stretching in both directions is biaxial stretching. Examples of the stretching method include known stretching between rolls and stretching performed by a tenter. In the polypropylene-based stretched sealant film 1 of the present invention, stretching in the winding direction (MD) by stretching between rolls is preferable. Hereinafter, the direction of uniaxial stretching (stretching direction of the film) in the present specification and Examples will be described as stretching in the winding direction (MD).

The base material layer 10 has a composition containing 50 to 85% by weight of the polypropylene resin (A) and 15 to 50% by weight of the thermoplastic elastomer (B). Therefore, flexibility due to the thermoplastic elastomer is added to the resin composition of the base material layer, and the bag breaking resistance is increased.

Here, when the polypropylene resin (A) is less than 50% by weight (when the thermoplastic elastomer (B) is more than 50% by weight), the component on the low melting point side increases. Therefore, poor appearance and blocking are likely to occur. In addition, the moldability tends to decrease due to the decrease in melting point. In addition, when the polypropylene-based resin (A) exceeds 85% by weight (the thermoplastic elastomer (B) is less than 15% by weight), the amount of the thermoplastic elastomer (B) added is small, so that the flexibility is insufficient. Therefore, it becomes difficult to exhibit the desired tear resistance.

The polypropylene-based resin (A) contains either a propylene homopolymer, a propylene-ethylene random copolymer, a propylene-ethylene-butene random copolymer, or a propylene-ethylene block copolymer. Of course, the selected resin may be one kind or a mixture of two kinds.

The thermoplastic elastomer (B) contains an elastomer resin (E) that satisfies the following relationships (b1) to (b3). In the first (b1), the density of the elastomer resin (E) is 0.860 to 0.895 g / cm ³ . When the density of the elastomer resin (E) is lower than this range, blocking is likely to occur due to a decrease in melting point. On the contrary, the elastomer resin (E) having a density higher than that range does not have sufficient bag breaking resistance.

In the second (b2), the melt flow rate (MFR) (190 ° C., 2.16 kg load) of the elastomer resin (E) is in the range of 0.5 to 10 g / 10 min. The 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 2 to 5 g / 10 min is more preferable.

As the third (b3), the elastomer resin (E) is either an olefin-based elastomer resin (E1) or a styrene-based elastomer resin (E2). Both elastomer resins (E1 and E2) are also compatible.

The olefin-based elastomer resin (E1) is a random copolymer of either ethylene, propylene, or 1-butene and an α-olefin having 2 to 8 carbon atoms (excluding monomers of the same type). The number of comonomer in α-olefin of the olefin elastomer resin (E1) depends on the alkene that can be introduced. For example, 1-butene, 1-hexene, 4-methyl-1-pentene and the like are introduced, and a plurality of types may be used. Here, there is no resin containing a comonomer having a comonomer having less than 2 carbon atoms (that is, 1). Further, it is almost difficult to obtain a resin containing a comonomer having a comonomer having 9 or more carbon atoms. Therefore, in consideration of practically available and appropriate performance, the appropriate range of carbon number of comonomer is 2 to 8.

The styrene-based elastomer resin (E2) has a styrene content of 30% by weight or less. If the styrene content is excessive, the compatibility tends to decrease and the appearance tends to be poor. Therefore, the styrene content is preferably 30% by weight or less in consideration of practical availability and performance.

The sealant layer 20 is a portion of the polypropylene-based stretched sealant film 1 that is responsible for heat seal fusion and the like. Therefore, a generally used olefin resin is used as the constituent resin of the sealant layer 20. Specifically, it is a propylene homopolymer, a propylene-ethylene random copolymer, a propylene-ethylene-butene random copolymer, a propylene-ethylene block copolymer, or the like. These resins may be used alone or as a mixture of two or more kinds. Therefore, the compatibility with the polypropylene-based resin (A) which is the constituent resin of the base material layer 10 is high, and the interlayer strength between the base material layer 10 and the sealant layer 20 is also ensured.

In addition to the above-mentioned resin, an appropriate additive is added to the base material layer 10 and the sealant layer 20 of the polypropylene-based stretched sealant film 1, if necessary. For example, various antistatic agents such as aliphatic amine compounds such as lauryl diethanolamine, myristyl diethanolamine and oleyl diethanolamine, aliphatic amide compounds such as lauryl diethanolamide, myristyl diethanolamide and oleyl diethanolamide, and polyhydric alcohols are appropriately added. Has been done. Further, various additives such as an anti-blocking agent, a heat stabilizer, an antioxidant, a light stabilizer, a crystal nucleating agent, and an ultraviolet absorber may be contained.

The polypropylene-based stretched sealant film 1 is laminated (laminated) with the film to be laminated 30 as shown in the schematic cross-sectional view of FIG. 2, to form the film laminate 50. The film to be laminated 30 is laminated on the second surface 12 side of the base material layer 10 of the polypropylene-based stretched sealant film 1. The laminating method is not limited, and known methods such as dry laminating, extruded laminating, and hot melt laminating are adopted depending on the purpose. A film of a general resin type is used for the film to be laminated film portion 30. For example, polypropylene film, polyethylene terephthalate (PET) film, polyester film such as polybutylene terephthalate, polyamide film (nylon film) and the like can be mentioned.

Additives such as an anti-blocking agent, an antistatic agent, an antioxidant, a neutralizing agent, and a coloring agent are added to the resin of the film to be laminated film 30 as needed.

FIG. 2A is a film laminate 50 in which a single-layer film to be laminated 30 is laminated. In addition, FIG. 2B is a film laminate 50 in which a multi-layer (two layers in the drawing) laminated film portions 30 are laminated. In the figure, reference numeral 31 is a first laminated film, and 32 is a second laminated film. In this way, when selecting the number of layers and the material of the film to be laminated, the optimum structure is selected in consideration of the application, function, durability, etc. of the final film, and it has easy tearing resistance and tear resistance. It is effectively used as various materials that combine the above.

Further, as shown in the film laminate 50A disclosed in the schematic cross-sectional view of FIG. 3, the film to be laminated 30 is provided with a metal layer 40. The number of layers and the material of the film to be laminated 30 are appropriate, and the position of the metal layer 40 in the film to be laminated 30 is also free. In the figure, the metal layer portion 40 is arranged at the lowermost part of the film to be laminated film 30, and the metal layer portion 40 is laminated with the second surface 12 side of the base material layer 10 of the polypropylene-based stretched sealant film 1. The metal layer portion 40 is formed of a metal foil such as aluminum, and can also be formed by vapor deposition of a metal such as aluminum. By providing the metal layer portion, the barrier property and the light-shielding property of the final film are enhanced. For example, it is suitable for packaging retort foods for long-term storage.

The polypropylene-based stretched sealant film 1 or the film laminate 50 (50A) is most often used to be cut into an appropriate shape and size and then processed into a bag shape by heat sealing between the sealant layers 20. Then, in the finished bag-shaped material, the portion that is likely to be fragile can be said to be the boundary between the heat-sealed portion and the non-heat-sealed portion. Therefore, it is necessary to evaluate the toughness of the heat-sealed portion when processed into a bag shape, that is, the bag breaking resistance.

In particular, in the case of the film laminate 50 (50A), many bag breakages occur near the fusion site due to heat sealing between the sealant films. That is, various stresses are instantaneously concentrated near the fusion site of the heat seal. Therefore, in order to improve the bag-breaking resistance, it is important to soften the base material layer 10 to absorb stress. The measurement of fracture energy is effective as an evaluation of the rupture resistance in which such stress is instantaneously concentrated.

Therefore, the breaking energy of the polypropylene-based stretched sealant film 1 in the film laminate 50 (50A) is measured as in the following measurement (I). The fracture energy based on the measurement is 0.1 J / 1.5 cm ² or more as disclosed in Examples described later. If this value is exceeded, durability and bag resistance will improve, and it is thought that the application as a material having both easy tearing property and bag tear resistance will expand. The higher the value of destructive energy, the more preferable. However, considering the current resin composition and the like, 1.0 J / 1.5 cm ² is considered to be the upper limit.

As the measurement (I), the sealant layer 20 sides of the film laminate 50 (50A) are heat-sealed so that the heat-sealed portion can be peeled off in the winding direction (so-called MD), and the heat-sealed portion HS is arranged in the center. Side view inverted Y-shaped test pieces 55 having non-heat-sealed portions are formed at both ends thereof (see the schematic views of FIGS. 4 and 5). In the figure, reference numerals 58 and 58 are hot plates (15 mm width) for heat sealing. The test piece 55 is cut out according to the type 3 described in the JIS K 7160 (1996) standard while leaving the heat-sealed portion HS of the test piece 55 in the center. The area of the heat-sealed portion HS of the test piece is 1.5 cm ² .

One end side of the test piece 55 (one end on the side not heat-sealed) is fixed to the jig 60 by the gripping tool described in the same standard, and the other end side of the test piece 55 is fixed by a 15 g crosshead 61. It is mounted on the crosshead support base 62. The striker 65 (hammer) that flicks off the crosshead 61 is lifted to 150 ° where the position energy is 2J, and the striker 65 is swung down by an arc motion from the same position. For the state of swinging down the striker, refer to JIS K 7160 (1996).

The striker 65 collides with the crosshead 61 having one end side of the test piece 55 fixed, and the heat-sealed portion HS of the test piece 55 is destroyed by the impact and the crosshead 61 is blown off. Then, the angle of the striker 65 at the time when the crosshead 61 is flipped and swung up is read. This result is substituted into the correction formula (fi) by the simple correction method based on the potential energy described in JIS K 7110 (1999) and 711-1 (2012), and the fracture energy (D) is calculated (J / 1.5 cm). ² ). The plastic deformation and kinetic energy correction of the crosshead were calculated by the correction formula described in Annex C of JIS K 7160 (1996).

Here, the symbols of the equation (fi) are as follows.
WR: Moment around the axis of rotation of the striker (Nm)
α: Striker lifting angle (°)
α': Striker swing-up angle (°) when the test piece is not attached
β: Swing-up angle (°) of striker when the test piece is broken

FIG. 6 is an enlarged schematic view (expected view) showing the vicinity of the heat-sealed portion HS of the test piece 55 to which the load is applied. In the film laminate 50 found in the test piece 55, it is assumed that the stress generated at the time of impact is concentrated on the boundary between the sealed portion and the unsealed portion of the heat-sealed sealant layer 20. S in the figure is a fracture point due to momentarily concentrated stress. Therefore, when an impact is applied to the test piece 55, if the base material layer 10 itself of the polypropylene-based stretched sealant film 1 does not have sufficient flexibility, conformability to deformation, etc., the vicinity of the heat-sealed portion is instantaneously generated. It cannot follow the deformation due to the concentrated stress and yields (fractures), resulting in a fracture portion S at the site. As a result, the bag-making resistance of the bag-making product is reduced.

Therefore, the resin composition for forming the base material layer 10 of the polypropylene-based stretched sealant film 1 is also blended with the thermoplastic elastomer (B) for the purpose of increasing the flexibility that tends to be insufficient only with the polypropylene-based resin (A). It is considered that the strength and deformation resistance of the base material layer 10 of the polypropylene-based stretched sealant film 1 are enhanced by balancing the blending amounts of both resins.

As shown in the results of the examples described later, when the breaking energy is less than 0.1 J / 1.5 cm ² , the difference from the existing sealant film or the like is small and the desired object of the present invention cannot be achieved. The larger the breaking energy, the higher the bag breaking resistance, which is desirable. However, in reality, the upper limit is considered to be approximately 1.0 J / 1.5 cm ² . It should be noted that the amount of fracture energy does not necessarily correlate with the layer thickness of the base material layer 10, but rather it is considered that the influence of the resin type constituting the base material layer 10 is large.

[Preparation of polypropylene-based stretched sealant film]
With respect to the polypropylene-based stretched sealant films of Examples 1 to 11 and Comparative Examples 1 to 5, the resin as a raw material was melted and kneaded based on the resin composition and the ratio of each layer shown in Tables 1 to 4 below. A sheet was prepared using a co-extruded T-die film forming machine, and uniaxially stretched in the winding direction (MD) by an inter-roll stretching machine to form a film. The draw ratio of both Examples and Comparative Examples was set to 5 times. The layer thickness of the base material layer and the sealant layer in the polypropylene-based stretched sealant film was the ratio in the table. Further, the sealant films of the produced Examples and Comparative Examples were laminated with the film to be laminated, which will be described later, by dry laminating to form a film laminate.

[Ingredients used]
<Polypropylene resin (A)>
The following raw materials were used as the polypropylene-based resin (A) forming the base material layer. In addition, MFR is expressed as a melt flow rate (the same applies hereinafter).
(Raw material 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
(Raw material 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 0.90 g / cm ³
(Raw material 03) Propylene-ethylene block copolymer: manufactured by Japan Polypropylene Corporation, trade name "Novatec BC6CB", MFR (230 ° C, 2.16 kg load) 2.5 g / 10 min, density 0.90 g / cm ³

<Thermoplastic elastomer (B)>
The following raw materials were used as the thermoplastic elastomer (B) forming the base material layer. The raw materials 04 to 09 are olefin-based elastomer resins (E1), and the raw materials 10 are styrene-based elastomer resins (E2).
(Raw material 04) Mitsui Chemicals, Inc., product name "Toughmer P-0280", MFR (190 ° C, 2.16 kg load) 2.9 g / 10 min, density 0.870 g / cm ³
(Raw material 05) Mitsui Chemicals, Inc., product name "Toughmer A-4085S", MFR (190 ° C, 2.16 kg load) 3.6 g / 10 min, density 0.885 g / cm ³
(Raw material 06) Made by Japan Polyethylene Corporation, product name "Kernel KS340T", MFR (190 ° C, 2.16 kg load) 3.5 g / 10 min, density 0.880 g / cm ³
(Raw material 07) Made by Dow Chemical Co., Ltd., Product name "AFFINITY KC8852G", MFR (190 ° C, 2.16 kg load) 3.0 g / 10 min, density 0.875 g / cm ³
(Raw material 08) Made by Dow Chemical Co., Ltd., product name "VERSIFY 3200", MFR (190 ° C, 2.16 kg load) 3.9 / 10 min, density 0.876 / cm ³
(Raw material 09) Mitsui Chemicals, Inc., product name "Toughmer BL2481", MFR (190 ° C, 2.16 kg load) 4.0 g / 10 min, density 0.900 g / cm ³
(Raw material 10) Made by Clayton Polymer Japan Co., Ltd., Product name "Clayton G1657MS", MFR (190 ° C, 2.16 kg load) 2.0 g / 10 min, density 0.890 g / cm ³ , styrene content 13% by weight

As the polypropylene-based resin (A) forming the sealant layer, the same raw material 01, 02, 03 resin as the polypropylene-based resin (A) forming the base material layer was used.

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 "Syricia 430") was used. The anti-blocking agent is not shown in the table because it is a very small amount.

<Laminated film part>
The following four types (FL1 to FL4) were used for the laminated film portion to be laminated on the sealant films of each Example and Comparative Example.
(Film FL1) A film composed of two layers, a biaxially stretched polyethylene terephthalate film and a biaxially stretched polyamide film.
The biaxially stretched polyethylene terephthalate film is manufactured by Futamura Chemical Co., Ltd., has a product name of "FE2001", and has a thickness of 12 μm.
The biaxially stretched polyamide film (nylon film) is manufactured by Unitika Ltd., has a product name of "Emblem NX", and has a thickness of 15 μm.
(Film FL2) A single-layer film of a biaxially stretched polyamide film (manufactured by Unitika Ltd., product name "emblem ON", thickness 15 μm) was used.
(Film FL3) A single-layer film of a biaxially stretched polyamide film (manufactured by Unitika Ltd., product name "emblem ONM", thickness 15 μm) was used.
(Film FL4) A single-layer film of biaxially stretched polypropylene film (manufactured by Futamura Chemical Co., Ltd., trade name "FOR", thickness 20 μm) was used.

<adhesive>
The adhesive (dry laminate adhesive) for laminating films is 17.2% by weight for the main agent (manufactured by Toyo Morton Co., Ltd., TM-329) and 17.2% by weight for the curing agent (manufactured by the same company, CAT-8B). , And 65.6% by weight of ethyl acetate were mixed and prepared.

[Preparation of film laminate]
<Laminated film part using FL1>
In producing the laminated film portion using the polypropylene-based stretched sealant films of Examples 1 to 11 and Comparative Examples 1 to 5, first, the biaxially stretched polyethylene terephthalate film and the biaxially stretched polyamide film were used as the above-mentioned adhesive. To form a two-layer laminated body. At this time, the coating amount of the adhesive (solid content) prepared above was 4 g / m ² . Subsequently, the same adhesive (solid content) was applied to the surface of the biaxially stretched polyamide film of the laminate as 4 g / m ² , dried at 80 ° C. for 30 seconds, and then the sealant films of each example and comparative example were applied. I stuck it.

<Laminated film part using FL2,3,4>
The adhesive (solid content) of the above preparation is applied to the surface of each of FL2, 3 and 4 to be laminated films as 4 g / m ² , dried at 80 ° C. for 30 seconds, and then the sealant films of the respective examples and comparative examples. Was pasted.

[Measurement of physical properties]
<Thickness to thickness ratio of each layer>
The thickness of the polypropylene-based stretched sealant film of each Example and Comparative Example was measured according to JIS K 7130 (1999), respectively. Further, the layer thicknesses of the base material layer and the sealant layer in the polypropylene-based stretched sealant film are adjusted by the discharge amount from the T die, and the thickness obtained by measuring the stretched sealant film is proportionally divided by the set ratio (ratio). Layer ratio) was calculated.

<Haze>
The haze of the polypropylene-based stretched sealant film of each Example and Comparative Example was measured using NDH-5000 manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS K 7136 (2000). Haze was adopted as an index of the quality of appearance.

<Laminate strength>
The laminate strength was as follows while complying with JIS K 6854-3 (1999). From the film laminate (including the sealant films of each Example and Comparative Example) produced by the above-mentioned attachment, a strip of 15 mm × 200 mm was cut out and used as a test piece. Of this test piece, 50 mm of the laminate in the longitudinal direction was peeled off in advance and opened in a T-shape in a side view. The sealant film side and the film to be laminated film side of the partially peeled test piece were opened at 180 ° opposite positions, and each was fixed to the chuck of a tensile tester (manufactured by Shimadzu Corporation, EZ-SX). The remaining laminated portion (laminated adhesive portion) was peeled off by pulling in the vertical direction at a test speed of 200 mm / min. The peeling was 100 mm, and the maximum peeling load during that period was taken as the lamination strength (N / 15 mm) of the test piece.

<Seal strength>
In the film laminate (including the sealant films of each example and comparative example) produced by the above-mentioned bonding, the sealant layers of the respective polypropylene-based stretched sealant films are overlapped with each other to control the heating temperature (manufactured by Fuji Impulse Co., Ltd.). , OPL-350-MD NP), heat seal the seal temperature and heating time in each table so that the heat seal part can be peeled off in the winding direction (MD) under the condition of 1.0 sec, and cut out with a width of 15 mm. It was used as a test piece. In this test piece, the end side that is not heat-sealed is opened to the opposite position of 180 °, and the heat-sealing strength (N / 15 mm) conforms to the "heat-sealing strength test of the bag" of JIS Z 0238 (1998). ) Was measured.

<Tear strength>
The tear strength was as follows, in accordance with JIS K 7128-1 (1998). About the film laminate (including the sealant film of each Example and Comparative Example) produced by the above-mentioned attachment, 150 × 50 mm in which the winding direction (MD) is a long side and the width direction (TD) is a short side. It was cut out into a rectangular test piece. A 75 mm notch was made along the longitudinal direction from the midpoint of the short side. The ends of both notches were opened at 180 ° up and down facing positions, and the ends were fixed to the chucks of a tensile tester (manufactured by Shimadzu Corporation, Autograph AG-1). This was pulled up and down to tear the test piece, and the value at the position where the tear amount exceeded 20 mm was defined as the tear strength (N) of the test piece.

<Destructive energy>
As described in the measurement (I) and FIGS. 4 and 5, the sealant layer sides of the film laminates (including the sealant films of each Example and Comparative Example) produced by the above-mentioned bonding are wound in the winding direction (MD). A heat-sealed part was heat-sealed so that the heat-sealed part could be peeled off, a heat-sealed part was arranged in the center, and a side-view inverted Y-shaped test piece having non-heat-sealed parts at both ends was prepared. The heat seal conditions were based on the above-mentioned "seal strength" measurement conditions. The hot plate used for the heat seal had a width of 15 mm. The test piece was cut out according to the type 3 described in the JIS K 7160 (1996) standard while leaving the heat-sealed portion of the test piece in the center. The area of the heat-sealed portion of the test piece is 1.5 cm ² .

Fix one end side of the test piece (one end on the side not heat-sealed) to the jig of a testing machine (manufactured by Yasuda Seiki Seisakusho Co., Ltd., No. 285-L tensile impact tester with low temperature tank) conforming to the same standard. The other end of the test piece was fixed to a 15 g crosshead. The crosshead was placed on the crosshead support. The striker that flicks off the crosshead was lifted to 150 °, where the potential energy is 2J, the stopper was removed, and the striker was swung down from the same position by circular motion.

The striker was made to collide with a crosshead having one end of the test piece fixed, and the angle of the striker at the time when the crosshead was flipped off and swung up was read. Obviously, the heat-sealed part of the test piece is destroyed by the impact of the collision between the striker and the crosshead. Then, by substituting into the correction formula (fi) by the simple correction method based on the potential energy described in JIS K 7110 (1999) and 711-1 (2012), the films are laminated using the sealant films of the respective examples and comparative examples. The destructive energy (D) in the body was calculated. Here, the plastic deformation and kinetic energy correction of the crosshead were calculated by the correction formula described in Annex C of JIS K 7160 (1996). The symbols in the formula (fi) are as follows, as described above.
WR: Moment around the axis of rotation of the striker (Nm)
α: Striker lifting angle (°)
α': Striker swing-up angle (°) when the test piece is not attached
β: Swing-up angle (°) of striker when the test piece is broken

With respect to the polypropylene-based stretched sealant films of Examples 1 to 11 and Comparative Examples 1 to 5 disclosed in Tables 1 to 4, film FL1 was used for the film to be laminated. In the table, in order from the top, the raw material resin type of the base material layer (10) and its blending ratio (% by weight), the raw material resin type of the sealant layer (20) and its blending ratio (% by weight), Examples and Comparative Examples. Thickness (μm) and haze (%) of polypropylene-based stretched sealant film, layer ratio of thickness of base material layer to sealant layer, lamination strength (N / 15 mm) when processed into film laminate, tear strength (N) ), Seal temperature (° C), seal strength (N / 15 mm), and breaking energy (J / 1.5 cm ² ). In addition, wt% in the table shows weight%.

At the same time, for the Examples and Comparative Examples in Tables 1 to 4, the following three stages of comprehensive evaluation were made by comprehensively considering the results of each index, manufacturing obstacles, and viewpoints on actual demand. Good products are evaluated as "A" and "B", and non-good products are evaluated as "F".
-Evaluation "A": "Especially excellent in all indicators."
・ Evaluation "B": "Generally excellent."
・ Evaluation "F": "Not suitable as a product."

In Tables 5, 6 and 7, the polypropylene-based stretched sealant films of Examples 2 and 8 having an overall evaluation of "A" and Comparative Example 1 having the same evaluation of "F" have films FL2 and FL3 on the laminated film portion. , And the physical properties when processed into a film laminate using FL4 are shown in the same manner as in Table 1 and the like.

[Results / Discussion]
Examples 1 to 11 were all good evaluations of "A" and "B". The difference between the evaluations of A and B is the result of taking into account the level of fracture energy and the degree of appearance. From the result of the layer ratio of each layer in the polypropylene-based stretched sealant film, the degree of freedom of the layer ratio between the base material layer and the sealant layer is high. Except for Example 9, the haze value is stable and low, and the transparency is maintained in appearance. In Example 9, since a propylene-ethylene block copolymer is used for the polypropylene-based resin (A), a uniform matte tone (matte tone) is exhibited and the haze value is high, but there is a problem in appearance. There are no points. Furthermore, due to its high sealing strength, it is suitable for retort applications containing aluminum foil and the like.

<Resin composition ratio of base material layer>
Focusing on the resin composition ratio of the base material layer, the fracture energy remained at a low value in the compositions not containing the thermoplastic elastomer (B) of Comparative Examples 1, 4 and 5. Therefore, from the comparison between Example 4 and Comparative Example 2, it was found that the thermoplastic elastomer (B) needs to be blended in an amount of 15% by weight or more in order to improve the numerical value of the fracture energy. Next, according to the example in which the thermoplastic elastomer (B) of Comparative Example 3 exceeded half, although it contributed to the improvement of the numerical value of the fracture energy, the appearance of the film deteriorated in the stretching step due to the increase in the elastomer component, so that it was practically used. Inappropriate. Therefore, it was determined that the boundary was between the blending amount of Example 8 and the blending amount. From the above, the preferable blending amount ratio of the polypropylene resin (A) and the thermoplastic elastomer (B) in the base material layer is in the range of 50 to 85% by weight and 15 to 50% by weight, more preferably 60 to 80% by weight. % And in the range of 40 to 20% by weight.

Further, from the comparison between Example 7 and Comparative Example 4 in which the amount of the thermoplastic elastomer (B) in the sealant film is the same, the numerical value of the fracture energy is improved by containing the thermoplastic elastomer (B) in the base material layer. did. From this, it was shown that the addition of the thermoplastic elastomer (B) should be a base material layer.

As for the polypropylene-based resin (A) contained in the base material layer, good results could be obtained even when various forms of polypropylene-based resin were used, as can be seen from the examples. In addition, the polypropylene resin of the sealant layer can be freely selected. Therefore, when producing the polypropylene-based stretched sealant film of the present invention, the degree of freedom in selecting the polypropylene-based resin of both layers is high. Therefore, the optimum resin can be selected in consideration of the application and purpose.

Focusing on the thermoplastic elastomer (B) contained in the base material layer, the density of the elastomer resin of the raw materials 04 to 10 is in the range of 0.869 to 0.890 g / cm ³ , and all the examples have good results. showed that. Therefore, the preferred density of the elastomer resin can be in the range of 0.860 to 0.895 g / cm ³ .

Next, the melt flow rate (190 ° C., 2.16 kg load) of the elastomer resin of the raw materials 04 to 10 was also in the range of 2.0 to 4.0 g / 10 min, and all the examples showed good results. .. Therefore, in consideration of a reasonable range, it was set to 0.5 to 10 g / 10 min.

Further, as the thermoplastic elastomer (B) itself, both the olefin-based (raw materials 04 to 09) and the styrene-based (raw materials 10) were good, so that any of them can be used.

The polypropylene-based stretched sealant film of the example was finished as a film laminate showing stable and good fracture energy even when the film to be laminated was changed to films FL1, FL2, FL3, FL4. Therefore, the types of laminated film portions that can be handled are wide and can be used properly according to the application, and the convenience as a material having both easy tearing property and bag tear resistance is extremely high.

The polypropylene-based stretched sealant film and film laminate of the present invention use the polypropylene-based stretched sealant film having excellent automatic packaging suitability, easy tearability, and strength by improving the resin composition of the base material layer portion in the composition. Since it is a film laminate, it is more suitable for applications such as packaging materials.

1 Polypropylene-based stretched sealant film 10 Base material layer 11 First surface of base material layer 12 Second surface of base material layer 20 Sealant layer 30 Laminated film 40 Metal layer part 50, 50A Film laminate 55 Test piece HS Heat seal site

Claims (4)

A polypropylene-based stretched sealant film (1) provided with a base material layer (10) and a heat-sealable sealant layer (20) on one side of the base material layer (10) and having a uniaxial stretching ratio of 3 to 10 times. ) And
The base material layer (10) contains 50 to 85% by weight of the polypropylene resin (A) and 15 to 50% by weight of the thermoplastic elastomer (B).
The polypropylene-based resin (A) contains any one of a propylene homopolymer, a propylene-ethylene random copolymer, a propylene-ethylene-butene random copolymer, or a propylene-ethylene block copolymer.
The thermoplastic elastomer (B) contains an elastomer resin (E) that satisfies the following relationships (b1) to (b3).
(B1): The density of the elastomer resin (E) is 0.860 to 0.895 g / cm ³ .
(B2): The melt flow rate (190 ° C., 2.16 kg load) of the elastomer resin (E) is 0.5 to 10 g / 10 min.
(B3): An olefin system in which the elastomer resin (E) is a random copolymer of any of ethylene, propylene, or 1-butene and α-olefin having 2 to 8 carbon atoms (excluding monomers of the same type). It is either an elastomer resin (E1) or a styrene-based elastomer resin (E2) having a styrene content of 30% by weight or less.
The sealant layer (20) is characterized by containing any one of a propylene homopolymer, a propylene-ethylene random copolymer, a propylene-ethylene-butene random copolymer, or a propylene-ethylene block copolymer. Polypropylene-based stretched sealant film. A film laminate (50) characterized in that the substrate layer (10) of the polypropylene-based stretched sealant film (1) according to claim 1 is provided with a film to be laminated (30). The film laminate according to claim 2, wherein the film to be laminated (30) is provided with a metal layer portion (40). The film laminate according to claim 2 or 3, wherein the breaking energy of the polypropylene-based stretched sealant film (1) in the film laminate (50) is 0.1 J / 1.5 cm ² or more in the following measurement (I). body.
Measurement (I): The sealant layer (20) sides of the film laminate (50) are heat-sealed so that the heat-sealed parts can be peeled off in the winding direction, and the heat-sealed parts are arranged in the center, and the heat-sealed parts are not arranged at both ends. A heat-sealed part is provided to form an inverted Y-shape when viewed from the side, and while leaving the heat-sealed part in the center, it is cut into a test piece according to the 3 form described in the JIS K 7160 (1996) standard and described in the same standard. One end side of the test piece is fixed by the gripping tool, and the other end side is fixed by a 15 g cross head and placed on the cross head support base. After raising the striker to 150 ° where the potential energy is 2J, the striker is swung down, and the striker collides with the crosshead having one end side of the test piece fixed to break the test piece to break the crosshead. Read the angle of the striker at the time of flipping and swinging up. Then, the fracture energy (D) was calculated based on the correction formula (fi) by the simple correction method based on the potential energy described in JIS K 7110 (1999) and 711-1 (2012). Here, the plastic deformation and kinetic energy correction of the crosshead were calculated by the correction formula described in Annex C of JIS K 7160 (1996).
WR: Moment around the axis of rotation of the striker (Nm)
α: Striker lifting angle (°)
α': Striker swing-up angle (°) when the test piece is not attached
β: Swing-up angle (°) of striker when the test piece is broken

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