JP2022166818A - Undrawn film for food packaging and bag for food packaging - Google Patents

Abstract

To provide an undrawn film for food packaging that retains sufficient performances required for a bag for food packaging and can suppress the blowout of a fuse part during food charging particularly at low temperatures, and provide the bag for food packaging.SOLUTION: An undrawn film 10 is used for bag-making by a fuse seal and comprises three layers of: a surface layer 20, an intermediate layer 30, and a seal layer 40, the surface layer subjected to corona treatment on the surface. The surface layer is predominantly composed of propylene resin. The intermediate layer is predominantly composed of a propylene resin composition that comprises a propylene-ethylene block copolymer with a xylene soluble content of 12% or more of 50 wt.% or more and has a calculated MFR of 6 g/10 min or less. The seal layer comprises a propylene elastomer with a density of 0.880 g/cm3 or less of 20-80 wt.% and a propylene-ethylene random copolymer of 20-80 wt.%.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a non-stretched food packaging film and a food packaging bag using this non-stretched film.

For example, a bag for packaging food such as loaf of bread is made into a gusset bag by fusion sealing, filled with food, and then the opening is sealed by heat sealing. The film constituting this type of food packaging bag is a non-stretched film, and a transparent film or a matte film is selected according to the type of food to be packaged. In particular, a matte finish is preferably used for packaging bags for packaging bread.

Since the heat-sealing of the opening of the packaging bag is performed at high speed, low-temperature heat-sealability is required. In addition, after the packaging bag is opened and some food is taken out, it is necessary to have an easy-to-open property that can be opened with a weak force without stretching or tearing the bag so that the opening can be closed again with a closure or the like. be done. Therefore, as a food packaging film having low-temperature heat-sealability and easy-openability while maintaining fusing strength, it is composed of 20 to 80% by weight of a propylene/α-olefin random copolymer and 80 to 20% by weight of a butene polymer. A polyolefin multilayer film having a heat-sealable layer and a propylene polymer layer is known (see, for example, Patent Document 1). This film is excellent in low-temperature heat-sealability and easy-openability while maintaining fusion strength, and is suitable for use as a packaging bag.

In addition, as other films used for food packaging bags, a printed layer containing 70% by mass or more of a propylene block copolymer resin, a propylene block copolymer resin of 15 to 90% by mass and a linear low A matte laminated film having an intermediate layer containing 5 to 30% by mass of density polyethylene and a sealing layer is known (see, for example, Patent Document 2). This matte film is excellent in low-temperature impact resistance, sealing strength, abrasion resistance, bag-breaking resistance, and fusion-cut sealing strength, and is suitable for bread packaging.

However, in a conventional food packaging bag, even if the seal surfaces have sufficient fusion strength, the fusion section may be torn when filling food such as bread, especially in winter or other periods when the temperature is low. there were. Therefore, each performance required for food packaging bags such as film tear resistance, fusion strength, low temperature sealability, easy opening, bag making suitability, etc. It is demanded to suppress the occurrence of tearing at the fusing part.

Japanese Patent Application Laid-Open No. 2002-210897 WO2017/018282

The present invention has been proposed in view of the above situation, and maintains each performance required for food packaging bags in good condition, and suppresses the occurrence of bag breakage (tear) at the fusion cut part when filling food at low temperatures. To provide an unstretched film for food packaging and a food packaging bag capable of

That is, the invention of claim 1 is a non-stretched film used for bag making by fusion sealing, comprising three layers of a surface layer, an intermediate layer, and a seal layer, wherein the surface layer surface is subjected to corona treatment, The surface layer is mainly composed of a propylene-based resin, and the intermediate layer contains 50% by weight or more of a propylene-ethylene block copolymer having a xylene-soluble content of 12% or more and is represented by the following formula (i). The seal layer is mainly composed of a propylene resin composition having a calculated MFR of 6 g/10 min or less, and is composed of 20 to 80% by weight of a propylene elastomer having a density of 0.880 g/cm ³ or less and 20 to 80% of a propylene random copolymer. It relates to an unstretched film for food packaging characterized by having a composition of weight %.
MFR _X : Calculated MFR of propylene-based resin composition (g/10min)
n: Total number of propylene-based resins constituting the propylene-based resin composition w _i : Mixing ratio of propylene-based resin i constituting the propylene-based resin composition MFR _i : MFR of propylene-based resin i constituting the propylene-based resin composition (g/10min)

The invention of claim 2 is a non-stretched film used for bag making by fusion sealing, comprising three layers of a surface layer, an intermediate layer, and a seal layer, wherein the surface layer surface is subjected to corona treatment, wherein the surface The layer is mainly composed of a propylene-based resin, and the intermediate layer contains 50% by weight or more of a propylene-ethylene block copolymer having a xylene-soluble content of 12% or more, and the calculated MFR represented by the above formula (i). is 6 g/10 min or less, and the sealing layer is composed of 20 to 80% by weight of a propylene elastomer having a density of 0.880 g/cm ³ or less and 18 to 78% by weight of a propylene random copolymer. % and 2 to 20% by weight of linear low-density polyethylene.

The invention of claim 3 relates to the unstretched film for food packaging according to claim 1 or 2, wherein the unstretched film has a haze value of 40% or more as measured according to JIS K 7136 (2000).

In the invention of claim 4, the intermediate layer comprises 70 to 98% by weight of the propylene-based resin composition and 2 to 30% by weight of linear low-density polyethylene having a density of 0.910 or more. It relates to the unstretched film for food packaging according to any one of the above.

According to a fifth aspect of the invention, there is provided a food packaging bag made of the unstretched food packaging film according to any one of the first to fourth aspects, which is formed by fusion cutting with the seal layer inside.

The invention of claim 6 relates to the food packaging bag of claim 5, which has a gusset portion at the bottom.

According to the non-stretched film for food packaging according to the invention of claim 1, it is used for bag making by fusion sealing, has three layers of a surface layer, an intermediate layer, and a seal layer, and the surface of the surface layer is subjected to corona treatment. In the unstretched film, the surface layer is mainly composed of a propylene-based resin, and the intermediate layer contains 50% by weight or more of a propylene-ethylene block copolymer having a xylene-soluble content of 12% or more. The seal layer is mainly composed of a propylene resin composition having an MFR of 6 g/10 min or less, and is composed of 20 to 80% by weight of a propylene elastomer having a density of 0.880 g/cm ³ or less and 20 to 80% by weight of a propylene random copolymer. %, each performance of the food packaging bag is good, and the occurrence of tearing at the fusing portion during filling of the food at low temperatures can be effectively suppressed.

According to the non-stretched film for food packaging according to the invention of claim 2, it is used for bag making by fusion sealing, has three layers of a surface layer, an intermediate layer, and a seal layer, and the surface of the surface layer is subjected to corona treatment. In the unstretched film, the surface layer is mainly composed of a propylene-based resin, and the intermediate layer contains 50% by weight or more of a propylene-ethylene block copolymer having a xylene-soluble content of 12% or more. The seal layer is mainly composed of a propylene resin composition having an MFR of 6 g/10 min or less, and is composed of 20 to 80% by weight of a propylene elastomer having a density of 0.880 g/cm ³ or less and 18 to 78% of a propylene random copolymer. 2% by weight and 2 to 20% by weight of linear low-density polyethylene, each performance of the food packaging bag is good, and especially effective in preventing the occurrence of tearing at the fusing part when filling food at low temperatures. can be effectively suppressed.

According to the unstretched film for food packaging according to the invention of claim 3, in the invention of claim 1 or 2, the unstretched film has a haze value of 40% or more measured in accordance with JIS K 7136 (2000). Therefore, a matte film suitable for packaging foods such as bread can be obtained.

According to the non-stretched film for food packaging according to the invention of claim 4, in the invention of any one of claims 1 to 3, the intermediate layer contains 70 to 98% by weight of the propylene-based resin composition and has a density of 0.5%. Since it contains 2 to 30% by weight of linear low-density polyethylene of 910 or more, the stiffness of the film is increased and the bag-making aptitude is improved.

According to the food packaging bag according to the invention of claim 5, it is made of the non-stretched film for food packaging according to any one of claims 1 to 4, and is made by fusion cutting with the seal layer inside. The strength of is improved, and the occurrence of tearing at the melted portion during food filling at low temperatures is suppressed.

According to the food packaging bag according to the invention of claim 6, in the invention of claim 5, since the bottom part has a gusset part, bread can be suitably packaged.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing of the unstretched film for food packaging which concerns on one Embodiment of this invention. 1 is a schematic plan view of a food packaging bag obtained by fusion-cutting a non-stretched film for food packaging. FIG. FIG. 2 is a schematic perspective view of a process of bag-making a non-stretched film for food packaging by fusion-cut sealing. FIG. 4 is a schematic cross-sectional view of a folded portion of a film folded by gusset folding;

A film 10 according to one embodiment of the present invention shown in FIG. 1 is a non-stretched film for food packaging, which includes three layers, a surface layer 20, an intermediate layer 30, and a sealing layer 40. FIG. This film 10 is manufactured by a known manufacturing method such as the T-die method.

The unstretched film for food packaging 10 is used as a material for food packaging bags for packaging appropriate foods, and is particularly suitable for packaging bags for bread such as loaves of bread and sweet buns. The appearance of the film 10 is configured to be transparent, matte (matte) or the like depending on the application, etc. A matte (matte) film is preferably used for bread packaging bags. Therefore, when the film 10 is to be matte, it is preferable to set the haze value measured according to JIS K 7136 (2000) to 40% or more. By setting the haze value to 40% or more, a matte film suitable for packaging foods such as bread can be obtained. Moreover, when making it into a transparent film, it is preferable to comprise a haze value to less than 10%.

The surface layer 20 is a layer mainly composed of propylene-based resin. This surface layer 20 corresponds to a printing layer on which appropriate printing is applied. Therefore, the surface of the surface layer 20 is subjected to corona treatment in order to obtain good printing performance on the surface of the film.

The propylene-based resin is selected from propylene-based polymers such as homopolymers of propylene (homopolypropylene) and copolymers of propylene with other olefins such as ethylene and butene (propylene copolymers). Specific examples of the resin constituting the surface layer 20 include propylene homopolymer, propylene-ethylene random copolymer, propylene-ethylene-butene random copolymer, and propylene homopolymer and propylene when used as a transparent film. Blends of random copolymers, blends of propylene homopolymers and/or propylene random copolymers and ethylene-based elastomers, and blends of propylene homopolymers and/or propylene random copolymers and propylene-based elastomers. . In the case of a matte film, propylene-ethylene block copolymers, blends of propylene-ethylene block copolymers and polyethylene, homopolypropylene and/or blends of propylene random copolymers and polyethylene, and the like can be used. A method for blending two or more resins can be selected from compounding, dry blending, and the like.

The intermediate layer 30 is a layer mainly composed of a propylene-based resin composition containing 50% by weight or more of a propylene-ethylene block copolymer having a xylene-soluble content of 12% or more. The xylene-soluble component of the propylene-ethylene block copolymer is considered to be an elastomer component that dissolves in xylene contained in the propylene-ethylene block copolymer. If the xylene soluble content of the propylene-ethylene block copolymer is less than 12%, the fusing portion may easily crack. Further, if the ratio of the propylene-ethylene block copolymer in the intermediate layer 30 is less than 50% by weight, the fusion-cut portion is likely to crack, which is not preferable.

The propylene-based resin composition used for the intermediate layer 30 has a calculated MFR of 6 g/10 min or less, as indicated by the following formula (i). Note that the calculated MFR is regarded as the MFR of the mixed resin, and if the calculated MFR of the propylene-based resin composition is higher than 6 g/10 min, the fusing portion may easily tear.

Here, the symbols of formula (i) are as follows.
MFR _X : Calculated MFR of propylene-based resin composition (g/10min)
n: Total number of propylene-based resins constituting the propylene-based resin composition w _i : Mixing ratio of propylene-based resin i constituting the propylene-based resin composition MFR _i : MFR of propylene-based resin i constituting the propylene-based resin composition (g/10min)

The intermediate layer 30 preferably contains linear low-density polyethylene having a density of 0.910 g/cm ³ or more in order to increase the stiffness of the film and improve bag-making suitability. Linear low-density polyethylene may be of plant or fossil origin. A preferable compounding ratio of the intermediate layer 30 is 70 to 98% by weight of the propylene-based resin composition and 2 to 30% by weight of linear low-density polyethylene having a density of 0.910 or more. If the blending ratio of the linear low-density polyethylene is too small, it is difficult to increase the stiffness of the film. be. Moreover, even if the density of the linear low-density polyethylene is too low, it is difficult to increase the stiffness of the film.

The sealing layer 40 is a layer that becomes the inner side of the packaging bag after bag making. The sealing layer 40 is composed of 20 to 80% by weight of a propylene elastomer having a density of 0.880 g/cm ³ or less and 20 to 80% by weight of a propylene random copolymer.

The propylene-based elastomer is particularly preferably produced by using a metallocene-based catalyst. Propylene-based elastomers produced by metallocene-based catalysts have the advantages of less stickiness in films due to less low-molecular-weight components, and less problems such as slipperiness and blocking even when blended in large amounts. If the blending ratio of the propylene-based elastomer is too small, the seal initiation temperature becomes high, and low-temperature heat-sealability may not be obtained. On the other hand, if the blending ratio is too large, the seal initiation temperature may become too low and the easy-open property may not be obtained. If the density of the propylene-based elastomer is higher than 0.880 g/cm ³ , the film may stretch when the seal portion is peeled off, making it difficult to obtain easy-openability.

Propylene random copolymers include, for example, binary random copolymers of propylene and ethylene, binary random copolymers of propylene and α-olefins, and propylene, ethylene and α-olefins having 4 to 12 carbon atoms. A ternary random copolymer and the like can be mentioned.

In another embodiment, the sealing layer comprises 20 to 80% by weight of a propylene-based elastomer having a density of 0.880 g/cm ³ or less, 18 to 78% by weight of a propylene random copolymer, and linear low-density polyethylene. A composition having a composition of 2 to 20% by weight may be used. In the seal layer according to another embodiment, by containing the linear low-density polyethylene in the above blending ratio, deterioration of the heat seal strength over time can be suppressed.

The surface layer 20, the intermediate layer 30, and the seal layer 40 may contain antiblocking agents, slip agents, antistatic agents, antifogging agents, heat stabilizers, antioxidants, light stabilizers, and crystals as needed. Various additives such as nucleating agents and offcuts can be appropriately added within a range that does not impair the characteristics of each layer. Various additives may be added directly to the powder after polymerization of each resin, or may be mixed in any process from preparing a high-concentration masterbatch to obtaining a film. When using a masterbatch, a small amount of resin may be unintentionally blended, but it can be used within a range that does not impair the properties of each layer.

The film 10 preferably has a thickness of 20 to 50 μm, more preferably 25 to 35 μm, from the viewpoint of ease of handling and strength. The thickness of each layer is not particularly limited, but for example, the ratio of each layer is set to 5 to 40% for the surface layer, 30 to 90% for the intermediate layer, and 5 to 30% for the seal layer, more preferably 10 to 30% for the surface layer. , an intermediate layer of 50 to 83%, and a seal layer of 7 to 20%.

The film 10 of the present invention is used for making bags by fusion sealing to obtain food packaging bags. In bag making by fusion sealing, a heated fusion cutting blade is pressed against the orthogonal direction of the folded part that will be the bottom of the unstretched film for food packaging folded back with the seal layer inside, and the bag is cut and heat-sealed. It is molded into a shape. The melt-cut bag-making method is appropriately selected from known methods, and a melt-cut bag having an appropriate shape such as a square-bottomed gusset bag is obtained.

The embodiment shown in FIG. 2 is a food packaging bag 50 having a square bottom gusset portion 53 on a bottom portion 52 formed by fusion cutting. In the illustrated food packaging bag 50, a bag side portion 54 (thick line portion in the figure) including the side portion 51a of the bag main body 51 and the side portion 53a of the square bottom gusset portion 53 is a fused portion 55 that is fused and sealed. . The food packaging bag 50 having the square bottom gusset portion 53 is suitable as a bread packaging bag.

Here, the bag-making process of the food packaging bag 50 having the square bottom gusset portion 52 will be described. First, as shown in FIG. 3(a), the folded portion 11 of the folded back film 10 is folded into a substantially W-shaped side by gusset folding. At this time, the film 10 is folded back so that the seal layer 40 faces inside. Subsequently, as shown in FIG. 3B, the film 10 including the gusset-folded folded portion 11 is folded, and both sides of the film 10 corresponding to the orthogonal direction of the folded portion 11 (dotted line portions in the figure) are folded. Fusion sealing is performed at 12,12. Then, as shown in FIG. 3(c), the film 10 is formed into a bag shape (50A) in which three sides of the folded portion 11 and the fused portions 54, 54, which are both side portions that are fused and sealed, are sealed. Thus, a food packaging bag 50 (see FIG. 4) is obtained.

As shown in FIG. 4, in the food packaging bag 50 manufactured by fusion-cut sealing, the film 10 is weld-cut sealed in four layers at the gusset-folded folded portion 11 . Therefore, in the folded portion 11 where the fusion-cut sealing is performed, the seal layers 40 inside the first-stage film 10a and the second-stage film 10b are sealed (sealed portion 15a), and the second-stage films 10b and 3 are sealed. The outer surface layers 20 of the film 10c of the stage are sealed together (seal portion 15b), and the seal layers 40 of the film 10c of the third stage and the film 10d of the fourth stage are sealed together (the seal portion 15b). 15c).

In the unstretched film 10 for food packaging of the present invention, when making a bag by fusion sealing, not only the sealing layers 40 but also the surface layers 20 can be firmly fusion-sealed.

[Preparation of fusion bag]
When producing the fusion cut bags of Prototype Examples 1 to 30, first, the materials described later are dry blended, and the surface layer, intermediate layer, and seal layer are formed in order from a three-layer co-extrusion T-die film molding machine by the T-die method. They were co-extruded to have thicknesses of 8 μm, 18 μm, and 4 μm to form unstretched films corresponding to the fusion-cut bags of Prototype Examples 1 to 30. Next, each of the produced non-stretched films was folded in half with the seal layer on the inside, and then a gusset fold with a square bottom was formed at the bottom, and a fusion bag making machine (manufactured by Totani Giken Kogyo Co., Ltd.; "HK-40V") was used. ) was used to make fusion-cut bags at a tip angle of a fusion cutting blade of 120°, a fusion cutting temperature of 350°C, and a bag-making speed of 194 sheets/min to obtain fusion-cut bags of Prototype Examples 1 to 30.

[Materials used]
The following resins were used as resin compositions for the surface layer, intermediate layer, and heat seal layer. As the characteristics of each resin, the melt flow rate (MFR) conforms to JIS K 7210 (2014), the value measured at 230 ° C., 2.16 kg for the propylene resin, and the value measured at 190 ° C., 2.16 kg for the ethylene resin, Density is a value measured according to JIS K7112.

Further, the xylene soluble content ratio (%) was determined for the resins A1 to A4. When determining the xylene soluble content, first 5 to 6 g of resin was taken and weighed (weight X of resin before dissolution). Next, this was dissolved in xylene under reflux, cooled and then centrifuged to separate a xylene soluble fraction and an insoluble fraction. The xylene-soluble fraction was further concentrated, and methanol was added to precipitate and precipitate, and the precipitate was collected by filtration, dried, and weighed (weight Y of xylene-soluble precipitate). . Therefore, from the weight X of the resin before dissolution and the weight Y of the precipitate of the xylene-soluble matter, the xylene-soluble matter ratio Z (%) was determined based on the following formula (ii).

Further, melting points (° C.) were obtained for resins B1 and C1 to C5. The melting point of the resin conforms to JIS K 7121 (2012) differential scanning calorimetry (DSC) measurement, using a differential scanning calorimeter (manufactured by Netch Japan Co., Ltd.; "DSC 214 Polyma"), the heating rate The melting peak temperature was determined from the DSC curve obtained when the temperature was raised at 10°C/min and was taken as the melting point.

・ Resin A1: propylene-ethylene block copolymer (manufactured by Japan Polypropylene Corporation; "BC3HF"), MFR (230 ° C., 2.16 kg): 8.5 g / 10 min, xylene soluble content 10.6%, density 0.9g/ ^cm3
・ Resin A2: Propylene-ethylene block copolymer (manufactured by Prime Polymer Co., Ltd.; "F-274NP"), MFR (230 ° C., 2.16 kg): 2.5 g / 10 min, xylene soluble content 15.8% , density 0.9 g/cm ³
・ Resin A3: propylene-ethylene block copolymer (manufactured by Japan Polypropylene Corporation; "BC6DRF"), MFR (230 ° C., 2.16 kg): 2.5 g / 10 min, xylene soluble content 16.2%, density 0.9g/ ^cm3
・ Resin A4: propylene-ethylene block copolymer (manufactured by Japan Polypropylene Corporation; "BC5FA"), MFR (230 ° C., 2.16 kg): 3.5 g / 10 min, xylene soluble content 12.4%, density 0.9g/ ^cm3

Resin B1: homopolypropylene (manufactured by Japan Polypropylene Corporation; "FB3B"), MFR (230°C, 2.16 kg): 7.5 g/10 min, density 0.9 g/cm ³ , melting point 163°C

Resin C1: propylene random copolymer (propylene-ethylene random copolymer) (manufactured by Japan Polypropylene Corporation; "WFW4M"), MFR (230°C, 2.16 kg): 7 g/10 min, density 0.9 g/cm ³ , melting point 135°C
・ Resin C2: Propylene random copolymer (propylene-ethylene random copolymer) (manufactured by Prime Polymer Co., Ltd.; "S235WC"), MFR (230 ° C., 2.16 kg): 11 g / 10 min, density 0.9 g / cm ³ , melting point 135°C
・Resin C3: Propylene random copolymer (propylene-ethylene random copolymer) (manufactured by Japan Polypropylene Corporation; "WFX5233"), MFR (230°C, 2.16 kg): 7 g/10 min, density 0.9 g/cm ³ , melting point 130°C
・ Resin C4: Propylene random copolymer (propylene-ethylene-butene random copolymer) (manufactured by Japan Polypropylene Corporation; "FW4BT"), MFR (230 ° C., 2.16 kg): 6.5 g / 10 min, density 0 .9 g/cm ³ , melting point 138°C
・ Resin C5: Propylene random copolymer (propylene-ethylene random copolymer) (manufactured by Japan Polypropylene Corporation; "WFX6"), MFR (230 ° C., 2.16 kg): 2 g / 10 min, density 0.9 g / cm ³ , melting point 125°C

・ Resin D1: Low density polyethylene (manufactured by Ube Maruzen Polyethylene Co., Ltd.; "R300"), MFR (190 ° C., 2.16 kg): 0.35 g / 10 min, density 0.920 g / cm ³

Resin E1: plant-derived linear low-density polyethylene ("SLH118" manufactured by Braskem), MFR (190°C, 2.16 kg): 1 g/10 min, density 0.916 g/cm ³
Resin E2: plant-derived linear low-density polyethylene ("SLH218" manufactured by Braskem), MFR (190°C, 2.16 kg): 2.3 g/10 min, density 0.916 g/ ^cm3
Resin E3: plant-derived linear low-density polyethylene ("SLL318" manufactured by Braskem), MFR (190°C, 2.16 kg): 2.7 g/10 min, density 0.918 g/cm ³
・Resin E4: Linear low-density polyethylene (manufactured by Ube Maruzen Polyethylene Co., Ltd.; “1540F”), MFR (190° C., 2.16 kg): 4 g/10 min, density 0.913 g/cm ³
・Resin E5: Linear low-density polyethylene (manufactured by Ube Maruzen Polyethylene Co., Ltd.; “0540F”), MFR (190° C., 2.16 kg): 4 g/10 min, density 0.904 g/cm ³
・ Resin E6: Linear low-density polyethylene (manufactured by Ube Maruzen Polyethylene Co., Ltd.; “2040FC”), MFR (190 ° C., 2.16 kg): 5 g / 10 min, density 0.919 g / cm ³
・ Resin E7: Linear low-density polyethylene (manufactured by Japan Polyethylene Co., Ltd.; "KF360T"), MFR (190 ° C., 2.16 kg): 3.5 g / 10 min, density 0.898 g / cm ³

・Resin F1: Metallocene-based catalyzed propylene-based elastomer (manufactured by ExxonMobil; "VISTAMAXX3980FL"), MFR (230°C, 2.16 kg): 8 g/10 min, density 0.878 g/cm ³
・Resin F2: Metallocene-based catalyst propylene-based elastomer (manufactured by ExxonMobil; "VISTAMAXX6102FL"), MFR (230°C, 2.16 kg): 3 g/10 min, density 0.862 g/cm ³
・Resin F3: Metallocene-based catalyst propylene-based elastomer (manufactured by ExxonMobil; "VISTAMAXX3588FL"), MFR (230°C, 2.16 kg): 8 g/10 min, density 0.889 g/cm ³

・Resin G1: metallocene-based catalyst ethylene-based elastomer (manufactured by Dow Chemical Co., Ltd.; "AFFINITY KC8852G"), MFR (190 ° C., 2.16 kg): 3 g / 10 min, density 0.875 g / cm ³

[Prototype example 1]
In prototype example 1, the surface layer is made of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is made of 100% by weight of resin A2, and the seal layer is made of 35% by weight of resin C1 and 65% by weight of resin F1. It is a fusion cut bag made of a non-stretched film.

[Prototype example 2]
In prototype example 2, the surface layer is made of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is made of 100% by weight of resin A3, and the sealing layer is made of 35% by weight of resin C1 and 65% by weight of resin F1. It is a fusion cut bag made of a non-stretched film.

[Prototype Example 3]
In prototype example 3, the surface layer is made of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is made of 100% by weight of resin A4, and the seal layer is made of 35% by weight of resin C1 and 65% by weight of resin F1. It is a fusion cut bag made of a non-stretched film.

[Prototype example 4]
In prototype example 4, the surface layer is made of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is made of 100% by weight of resin A2, and the sealing layer is made of 80% by weight of resin C3 and 20% by weight of resin F2. It is a fusion cut bag made of a non-stretched film.

[Prototype Example 5]
In Prototype Example 5, the surface layer is composed of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is composed of 85% by weight of resin A2 and 15% by weight of resin E5, and the seal layer is composed of 35% by weight of resin C1. It is a fusion-cut bag made of a non-stretched film formed with 65% by weight of F1.

[Prototype Example 6]
In Prototype Example 6, the surface layer is composed of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is composed of 60% by weight of resin A2 and 40% by weight of resin E2, and the seal layer is composed of 35% by weight of resin C1. It is a fusion-cut bag made of a non-stretched film formed with 65% by weight of F1.

[Prototype Example 7]
In prototype example 7, the surface layer is composed of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is composed of 98% by weight of resin A2 and 2% by weight of resin E2, and the sealing layer is composed of 35% by weight of resin C1. It is a fusion-cut bag made of a non-stretched film formed with 65% by weight of F1.

[Prototype Example 8]
In prototype example 8, the surface layer is composed of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is composed of 85% by weight of resin A2 and 15% by weight of resin E1, and the seal layer is composed of 35% by weight of resin C1. It is a fusion-cut bag made of a non-stretched film formed with 65% by weight of F1.

[Prototype Example 9]
In prototype example 9, the surface layer is composed of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is composed of 85% by weight of resin A2 and 15% by weight of resin E3, and the sealing layer is composed of 35% by weight of resin C1. It is a fusion-cut bag made of a non-stretched film formed with 65% by weight of F1.

[Prototype Example 10]
In prototype example 10, the surface layer is composed of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is composed of 70% by weight of resin A2 and 30% by weight of resin E2, and the seal layer is composed of 35% by weight of resin C1. It is a fusion-cut bag made of a non-stretched film formed with 65% by weight of F1.

[Prototype Example 11]
In prototype example 11, the surface layer contains 95% by weight of resin A1 and 5% by weight of resin D1, and the intermediate layer contains 50% by weight of resin A2, 25% by weight of resin C1, 15% by weight of resin E2, and 10% by weight of resin E4. 80% by weight of resin C3 and 20% by weight of resin F2.

[Prototype Example 12]
In prototype example 12, the surface layer contains 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer contains 70% by weight of resin A2, 15% by weight of resin C1 and 15% by weight of resin E2, and the sealing layer is made of resin. It is a fusion-cut bag made of a non-stretched film formed with 80% by weight of C3 and 20% by weight of resin F2.

[Prototype Example 13]
In Prototype Example 13, the surface layer is composed of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is composed of 50% by weight of resin A2, 35% by weight of resin C2 and 15% by weight of resin E2, and the sealing layer is made of resin. It is a fusion-cut bag made of a non-stretched film formed with 35% by weight of C1 and 65% by weight of resin F1.

[Prototype Example 14]
In prototype example 14, the surface layer is made of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is made of 100% by weight of resin A1, and the seal layer is made of 35% by weight of resin C1 and 65% by weight of resin F1. It is a fusion cut bag made of a non-stretched film.

[Prototype Example 15]
In prototype example 15, the surface layer is made of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is made of 100% by weight of resin B1, and the sealing layer is made of 35% by weight of resin C1 and 65% by weight of resin F1. It is a fusion cut bag made of a non-stretched film.

[Prototype Example 16]
In prototype example 16, the surface layer is made of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is made of 100% by weight of resin C4, and the sealing layer is made of 35% by weight of resin C1 and 65% by weight of resin F1. It is a fusion cut bag made of a non-stretched film.

[Prototype Example 17]
In Prototype Example 17, the surface layer is made of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is made of 100% by weight of resin A2, and the seal layer is made of 100% by weight of resin F1. It is a fusing bag.

[Prototype Example 18]
In Prototype Example 18, the surface layer is made of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is made of 100% by weight of resin A2, and the seal layer is made of 100% by weight of resin F3. It is a fusing bag.

[Prototype Example 19]
In prototype example 19, the surface layer was made of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer was made of 100% by weight of resin A2, and the seal layer was made of 60% by weight of resin C3 and 40% by weight of resin G1. It is a fusion cut bag made of a non-stretched film.

[Prototype example 20]
In prototype example 20, the surface layer is made of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is made of 100% by weight of resin A2, and the sealing layer is made of 80% by weight of resin C3 and 20% by weight of resin G1. It is a fusion cut bag made of a non-stretched film.

[Prototype Example 21]
In Prototype Example 21, the surface layer is composed of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is composed of 30% by weight of resin A2, 55% by weight of resin C5 and 15% by weight of resin E2, and the sealing layer is made of resin. It is a fusion-cut bag made of a non-stretched film formed with 35% by weight of C1 and 65% by weight of resin F1.

[Prototype Example 22]
In prototype example 22, the surface layer is made of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is made of 100% by weight of resin A2, and the seal layer is made of 35% by weight of resin C4 and 65% by weight of resin F1. It is a fusion cut bag made of a non-stretched film.

[Prototype Example 23]
In prototype example 23, the surface layer is composed of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is composed of 100% by weight of resin A2, and the seal layer is composed of 25% by weight of resin C1 and 65% by weight of resin F1. It is a fusion-cut bag made of a non-stretched film formed with 10% by weight of E6.

[Prototype Example 24]
In Prototype Example 24, the surface layer is composed of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is composed of 100% by weight of resin A2, and the seal layer is composed of 25% by weight of resin C1 and 65% by weight of resin F1. It is a fusion-cut bag made of a non-stretched film formed with 10% by weight of E7.

[Prototype Example 25]
In Prototype Example 25, the surface layer is composed of 95% by weight of resin A1 and 5% by weight of resin D1, the intermediate layer is composed of 100% by weight of resin A2, and the sealing layer is composed of 18% by weight of resin C1 and 65% by weight of resin F1. It is a fusion-cut bag made of a non-stretched film formed with 3.5% by weight of E6 and 13.5% by weight of resin E7.

[Prototype Example 26]
Prototype Example 26 is a non-stretched film produced by forming the surface layer with 100% by weight of resin C3, the intermediate layer with 100% by weight of resin A2, and the sealing layer with 35% by weight of resin C1 and 65% by weight of resin F1. It is a fusing bag.

[Prototype Example 27]
In prototype example 27, the surface layer is made of 100% by weight of resin C3, the intermediate layer is made of 50% by weight of resin A3 and 50% by weight of resin C1, and the sealing layer is made of 35% by weight of resin C1 and 65% by weight of resin F1. It is a fusion cut bag made of a non-stretched film.

[Prototype Example 28]
Prototype Example 28 is a non-stretched film produced by forming the surface layer with 100% by weight of resin C3, the intermediate layer with 100% by weight of resin A4, and the seal layer with 35% by weight of resin C1 and 65% by weight of resin F1. It is a fusing bag.

[Prototype Example 29]
Prototype Example 29 is a non-stretched film produced by forming the surface layer with 100% by weight of resin C3, the intermediate layer with 100% by weight of resin A2, and the seal layer with 80% by weight of resin C3 and 20% by weight of resin F2. It is a fusing bag.

[Prototype Example 30]
In prototype example 30, the surface layer is made of 100% by weight of resin C3, the intermediate layer is made of 100% by weight of resin A2, and the seal layer is made of 30% by weight of resin C1, 65% by weight of resin F1, and 5% by weight of resin E6. It is a fusion cut bag made of a non-stretched film.

Tables 1 to 5 show the resin composition of each layer of the film constituting the fusion-cut bag of Prototype Examples 1-30.

The performance evaluation of each film used in the fusion-cut bags of Prototype Examples 1 to 30 includes heat-seal initiation temperature, easy-openability, haze value, tensile elastic modulus, fusion-cut strength of the gusset portion, fusion-cut strength of the bag body, and content filling. It was measured about the breakage of the fused part at the time. Each test was conducted indoors at 23°C.

[Heat seal start temperature]
For the films corresponding to Prototype Examples 1 to 30, the heat seal initiation temperature was measured according to JIS Z 1713 (2009). Using a heat seal tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.; "thermal gradient tester"), 2 sheets of each film were prepared with a seal bar shape of 10 mm × 25 mm, a seal pressure of 0.4 MPa, and a seal time of 1 second. Then, the seal layers were overlapped and heat-sealed. After heat-sealing, cut out a 15 mm wide test piece, open the heat-sealed test piece at 180 °, and use a tensile tester (manufactured by Shimadzu Corporation; "Small desktop tester EZ-SX") to 200 mm. The temperature at which the heat seal strength reached 3 N/15 mm width (heat seal initiation temperature) was determined by peeling the sealed portion at a tensile speed of /min. Low-temperature sealability was evaluated as "good (◯)" when the measured heat seal initiation temperature was 80 to 120°C, and "poor (x)" when it was less than 80°C or greater than 120°C.

[Ease of opening]
The films corresponding to Prototype Examples 1 to 30 were tested for ease of opening. Using a heat seal tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.; "thermal gradient tester"), in the same manner as measuring the heat seal start temperature, prepare two sheets of each film and separate the seal layers. They were overlapped and heat-sealed at 120°C. After heat-sealing, cut out a 15 mm wide test piece, open the heat-sealed test piece at 180 °, and use a tensile tester (manufactured by Shimadzu Corporation; "Small desktop tester EZ-SX") to 200 mm. The state of peeling when the test piece was pulled at a tensile speed of /min was visually observed. The easy-openability was evaluated as "Good (O)" when the film was peeled without elongation, and as "Fail (X)" when the film was peeled with elongation. In addition, when it was not heat-sealed (no low-temperature sealability), it was indicated as "no seal (-)".

[Haze value]
The haze values of the films corresponding to Prototype Examples 1 to 30 were measured according to JIS K 7136 (2000). The haze value (%) is an index of transparency, and was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd.; "Haze meter NDH-4000"). In food packaging bags for bread and the like, matte films tend to be preferred by food manufacturers and consumers because of their better appearance than transparent films. Therefore, if the measurement result is 40% or more, it is "excellent (◎)", if it is less than 10%, it is "good (○)", and if it is 10% or more and less than 40%, it is "improper (x)". value was evaluated.

[Tensile modulus]
The tensile modulus (GPa) of the films corresponding to Prototype Examples 1 to 30 was measured according to JIS K 7127 (1999). Using a tensile tester (manufactured by A&D Co., Ltd.; "Tensilon universal material testing machine RTF-1310"), the winding direction (MD) of each film and the transverse direction (TD) perpendicular to it. Measurements were taken at If the measurement result is 0.65 GPa or more, it is “excellent (◎)”, if it is 0.50 GPa or more, it is “good (◯)”, and if it is less than 0.50 GPa, it is “improper (x)”. evaluated the strength of

[Fusing Strength of Gusset Part]
For the fusion-cut bags of Prototype Examples 1 to 30, the fusion-cut strength (N/15 mm width) of the fusion-cut portion (reference numeral 53a in FIG. 2) of the gusset portion was measured. In this measurement, the fused part of the gusset part of the fused bag is cut into a width of 15 mm, and a tensile tester (manufactured by Shimadzu Corporation; "Small desktop tester EZ-SX") is used to apply two films to each of the upper and lower chucks. It was sandwiched and pulled at 200 mm/min, and the maximum strength until the fusion part broke was determined. The fusion strength of the gusset portion was evaluated as "good (o)" when the measurement result was 15 N/15 mm width or more, and "failed (x)" when it was less than 15 N/15 mm width.

[Welding strength of bag body]
For the fusion-cut bags of Prototype Examples 1 to 30, the fusion-cut strength (N/15 mm width) of the fusion-cut portion (reference numeral 51a in FIG. 2) of the bag body was measured. In this measurement, the fused part of the bag body (the part that is not the gusset part) of the fused bag is cut to a width of 15 mm, and a tensile tester (manufactured by Shimadzu Corporation; "Small desktop tester EZ-SX") One sheet of each film was sandwiched and pulled at 200 mm/min, and the maximum strength until the fused portion was broken was determined. When the measurement result was 17 N/15 mm width or more, it was evaluated as "Good (O)", and when it was less than 17 N/15 mm width, it was evaluated as "Failure (X)".

[Evaluation of Tear Resistance of Fused Portion of Bag Body]
For the fusion-cut bags of Prototype Examples 1 to 30, a tear resistance test was conducted on the fusion-cut portion of the bag body (reference numeral 51a in FIG. 2) as an evaluation of the tear resistance of the fusion-cut portion due to the impact during filling of the contents (food). . In the fused bag breakage test, a fused bag is placed on the desk, both hands are placed inside the bag, and both hands are vigorously hit against the fused parts on both the left and right sides of the fused bag to check whether the fused bag has broken (teared). was visually observed. This bag-breaking test was conducted by preparing five fusion-cut bags of each of Prototype Examples 1 to 30. Out of the five fused bags, if none of the bags were broken, it was rated as “excellent (◎)”; if only one bag was broken, it was rated as “good (〇)”; When the bag was generated, it was evaluated as "impossible (x)" and the resistance to tearing of the melted portion during filling was evaluated.

Tables 6 to 10 show the test results and judgments of the films corresponding to the fusion cut bags of Prototype Examples 1 to 30 and the fusion cut bags of Prototype Examples 1 to 30. In addition, the calculated MFR of the intermediate layer propylene-based resin composition (resins A1 to A4, resin B1, resins C1 to C5) of each of Prototype Examples 1 to 30 was obtained based on the above formula (i), and Tables 6 to 10 It was shown to. In Tables 6 to 10, as a comprehensive evaluation, if the judgment of each test is all "good (〇)" or higher, it is "good (〇)", "improper (×)" or "no seal (-)". The case where there is at least one was set as "impossible (x)".

[Results and discussion]
As shown in Tables 1 to 5 and Tables 6 to 10, the overall evaluation of prototype examples 1 to 13 and 22 to 30 is "good (○)", and the overall evaluation of prototype examples 14 to 21 is "improper (x).""Met. Therefore, the differences in performance between the non-defective prototypes 1 to 13 and 22 to 30 and the defective prototypes 14 to 21 will be discussed by comparing the film configurations of the respective prototypes.

All of Prototype Examples 1 to 25 had a haze value of 40% or more, and all of Prototype Examples 26 to 30 had a haze value of less than 10%. That is, in Prototype Examples 1 to 25, the surface layer was composed mainly of a propylene-ethylene block copolymer, and a good matte tone was obtained, and in Prototype Examples 26 to 30, the surface layer was mainly composed of a propylene random copolymer. Good transparency was obtained with the composition.

In Prototype Examples 1 to 3, which are good products, and Prototype Example 14, which is a defective product, the propylene-based resin composition constituting the intermediate layer is 100% by weight of a propylene-ethylene block copolymer, and the type of propylene-ethylene block copolymer is different. (Resin A1, Resin A2, Resin A3, Resin A4) are different. In Prototype Example 1, the resin A2 has a xylene-soluble content of 15.8%. In Prototype Example 2, the resin A3 has a xylene-soluble content of 16.2%. In Prototype Example 3, the resin A4 has a xylene-soluble content of 12.4%. is used, and in Prototype Example 4, resin A1 having a xylene soluble content of 10.6% is used. Resin A1 used in Prototype Example 14 has a lower xylene-soluble content ratio than Resins A2 to A4 used in other Prototype Examples 1 to 3. Moreover, in Prototype Example 14, the calculated MFR of the propylene-based resin composition for the intermediate layer is higher than in Prototype Examples 1-3. As a result, in Prototype Example 14, the bag was more likely to break at the fusion-cut portion than in Prototype Examples 1-3. Therefore, the propylene-based resin composition (propylene-ethylene block copolymer) for the intermediate layer has a high calculated MFR and a low xylene-soluble content (for example, Resin A1; calculated MFR is 8.5 g/10 min, xylene 10.6% solubles) is considered unfavorable.

In contrast to the non-defective prototype examples 1 to 3, the defective prototype example 15 uses homopolypropylene (resin B1) instead of the propylene-ethylene block copolymer as the propylene-based resin composition constituting the intermediate layer. The difference is that Further, in contrast to the non-defective prototype examples 1 to 3, in the defective prototype example 16, a propylene random copolymer ( The difference is that the resin C4) is used. In both Prototype Examples 15 and 16, the melted portion was more likely to break than in Prototype Examples 1-3. Therefore, it is not preferable to use homopolypropylene (resin B1) or propylene random copolymer (resin C4) instead of propylene-ethylene block copolymer as the propylene-based resin composition for the intermediate layer.

Prototype Example 13, which is a good product, and Prototype Example 21, which is a defective product, are compared. In Prototype Example 13, the propylene-based resin composition constituting the intermediate layer was mainly composed of a propylene-based resin composition containing a propylene-ethylene block copolymer (resin A2) and a propylene random copolymer (resin C2) ( 50% by weight or more) and linear low-density polyethylene (resin E2). Prototype Example 21 differs from Prototype Example 13 in that the blending ratio of the propylene-ethylene block copolymer (resin A2) in the propylene-based resin composition is small (less than 50% by weight). In Prototype Example 21, the bag was more likely to break at the fusion-cut portion than in Prototype Example 13. Therefore, it is considered preferable that the propylene-based resin composition for the intermediate layer is mainly composed of a propylene-ethylene block copolymer (50% by weight or more).

Here, prototype example 1 of a good product and prototype examples 5 to 13 of good products are compared. In Prototype Example 1, the intermediate layer is 100% by weight of the propylene-based resin composition (propylene-ethylene block copolymer), whereas in Prototype Examples 5-13, the propylene-based resin composition (propylene-ethylene block copolymer , or propylene-ethylene block copolymer and propylene random copolymer), and linear low-density polyethylene (resin E1 to resin E5) is blended.

In Prototype Examples 8 to 13, compared with Prototype Example 1, the tensile elastic moduli in the winding direction (MD) and the transverse direction (TD) are almost "excellent (◎)", and the stiffness of the film is high. improvement was seen. Also, in Prototype Example 7, the tensile modulus was judged to be “good (◯)”, and compared with Prototype Example 1, the tensile modulus was improved. On the other hand, in Prototype Examples 5 and 6, compared with Prototype Example 1, no improvement in tensile elastic modulus was observed. Comparing Prototype Example 5 with Prototype Examples 8 and 9, the density of the linear low-density polyethylene (resin E5) used in Prototype Example 5, in which the tensile modulus was not improved, was lower than that of Prototype Examples 8 and 9. was low. Comparing Prototype Example 6 with Prototype Examples 7 and 10, Prototype Example 6, in which the tensile modulus was not improved, contained a higher proportion of linear low-density polyethylene (resin E2) than Prototype Examples 7 and 10. .

As can be understood from Prototype Examples 1, 5 to 13, the stiffness of the film can be improved by blending linear low-density polyethylene in the intermediate layer. As for the type of linear low-density polyethylene, it is considered preferable if the density is about 0.910 g/cm ³ or more. In addition, the blending ratio of the linear low-density polyethylene improves the tensile modulus even with a trace amount (for example, 2% by weight in Prototype Example 7), and when it becomes excessive (for example, 40% by weight in Prototype Example 6), the tensile elastic modulus 2 to 30% by weight is considered to be preferable because the content does not improve.

In prototype example 17, which is a defective product, the seal layer of prototype example 1, which is a good product, is composed of 65% by weight of a propylene elastomer (resin F1) produced by a metallocene catalyst and 35% by weight of a propylene random copolymer (resin C1). On the other hand, the sealing layer is different in that it is composed of 100% by weight of a propylene-based elastomer (resin F1) produced by a metallocene-based catalyst. Prototype Example 17 did not have suitable easy-open performance because the heat-sealed portion peeled off with elongation in the easy-open test. In addition, the defective product, Prototype Example 18, was composed of 100% by weight of a propylene-based elastomer (resin F3) having a different density from that of Prototype Example 17, but similarly did not have appropriate easy-opening performance.

Prototype Example 20, which is a defective product, is different from Prototype Example 4, which is a good product. G1) is used. In Prototype Example 20, the heat-seal initiation temperature was 126°C, and heat-sealing could not be performed at 120°C, and low-temperature sealability could not be obtained. In addition, in prototype example 19, which is a defective product, the blending ratio of the ethylene-based elastomer (resin G1) of prototype example 20 is increased (40% by weight). , The fusing strength of the fusing part of the bag body was insufficient, and the fusing part was easy to break.

As can be understood from Prototype Examples 1 and 4 and Prototype Examples 17 to 20, it is considered preferable that the seal layer is composed of a propylene-based elastomer and a propylene random copolymer. As for the type of propylene-based elastomer, it is considered that the density should be about 0.880 g/cm ³ or less. Moreover, it is considered that the blending ratio of the propylene-based elastomer is preferably about 20 to 80% by weight.

In Prototype Example 22, the propylene random copolymer (resin C1: propylene-ethylene random copolymer) used in the seal layer of Prototype Example 1 was replaced with a different propylene random copolymer (resin C4: propylene-ethylene-butene random copolymer). Prototype Example 22 was found to be slightly different from Prototype Example 1 in the heat-sealing initiation temperature and tensile modulus, but the film performance was not significantly affected and was good.

In Prototype Examples 23 to 25, linear low-density polyethylene was added to suppress deterioration in heat seal strength over time without changing the blending ratio of the main component (propylene-based elastomer) of the seal layer of Prototype Example 1. It is. Prototype Examples 23 and 24 each used different linear low-density polyethylenes, and Prototype Example 25 used a mixture of the two types of linear low-density polyethylenes used in Prototype Examples 23 and 24. In Prototype Examples 23 to 25, the heat-sealing temperature and the fusing strength of the bag body were slightly different from those in Prototype Example 1, but the performance of the film was not significantly affected and was good.

Prototypes 26 to 30 are transparent films with a haze value of less than 10%. Compared to Prototype Example 1, Prototype Examples 26 to 28 showed improvement in tensile elastic modulus and fusion strength of the gusset portion. Also, in prototype example 29, improvement in the tensile modulus of elasticity and the fusing strength of the gusset portion was observed as compared with prototype example 4. On the other hand, Prototype Example 30 contained linear low-density polyethylene for suppressing deterioration in heat seal strength over time without changing the blending ratio of the main component (propylene-based elastomer) of the seal layer of Prototype Example 26. For example. In Prototype Example 30, film performance comparable to that of Prototype Example 26 was obtained even when linear low-density polyethylene was included.

As described above, in the matte fusion-cut bags of Prototype Examples 1 to 13 and 22-25, low-temperature sealability (heat-seal initiation temperature), easy-openability, film stiffness (tensile modulus), fusion-cut portion Both performances of fusion cutting strength and resistance to tearing of the fusion cut portion during filling of the contents (evaluation of tear resistance of the fusion cut portion of the bag body) were good. In addition, in the transparent fusion-cut bags of Prototype Examples 26 to 30, low-temperature sealability (heat-seal initiation temperature), easy-openability, film stiffness (tensile modulus), fusion-cut strength of the fusion-cut portion, contents Each performance of tear resistance of the fusion cut portion during filling (evaluation of tear resistance of the fusion cut portion of the bag body) was good. Therefore, it is possible to effectively suppress the occurrence of tearing at the fusing portion during food filling even at low temperatures, while maintaining favorable performances required for food packaging bags.

The unstretched film for food packaging and the food packaging bag of the present invention can satisfactorily maintain each performance required for food packaging bags, and in particular, can suppress the occurrence of tearing at the fusion-cut portion during food filling at low temperatures. can. Therefore, it is promising as a substitute for conventional unstretched films for food packaging and food packaging bags.

REFERENCE SIGNS LIST 10, 10a to 10d Unstretched film for food packaging 11 Folding part 12 Side part of film 15a, 15b, 15c Sealing part 20 Surface layer 30 Intermediate layer 40 Sealing layer 50 Food packaging bag 50A Bag-shaped film 51 Bag body 51a Bag Side of body 52 Bottom 53 Square bottom gusset 53a Side of square bottom gusset 54 Bag side 55 Fusing seal

Claims (6)

A non-stretched film used for bag making by fusion sealing, comprising three layers of a surface layer, an intermediate layer, and a seal layer, wherein the surface layer surface is subjected to corona treatment,
The surface layer is mainly made of propylene-based resin,
The intermediate layer contains 50% by weight or more of a propylene-ethylene block copolymer having a xylene soluble content of 12% or more and a propylene-based resin having a calculated MFR of 6 g/10 min or less as shown in the following formula (i). mainly composed of a composition,
A non-stretched film for food packaging, wherein the sealing layer is composed of 20 to 80% by weight of a propylene elastomer having a density of 0.880 g/cm ³ or less and 20 to 80% by weight of a propylene random copolymer. .
MFR _X : Calculated MFR of propylene-based resin composition (g/10min)
n: Total number of propylene-based resins constituting the propylene-based resin composition w _i : Mixing ratio of propylene-based resin i constituting the propylene-based resin composition MFR _i : MFR of propylene-based resin i constituting the propylene-based resin composition (g/10min)

A non-stretched film used for bag making by fusion sealing, comprising three layers of a surface layer, an intermediate layer, and a seal layer, wherein the surface layer surface is subjected to corona treatment,
The surface layer is mainly made of propylene-based resin,
The intermediate layer contains 50% by weight or more of a propylene-ethylene block copolymer having a xylene-soluble content of 12% or more, and a propylene-based resin having a calculated MFR of 6 g/10 min or less as shown in the above formula (i). mainly composed of a composition,
The seal layer comprises 20 to 80% by weight of a propylene elastomer having a density of 0.880 g/cm ³ or less, 18 to 78% by weight of a propylene random copolymer, and 2 to 20% by weight of a linear low density polyethylene. A non-oriented film for food packaging, characterized by comprising: The unstretched film for food packaging according to claim 1 or 2, wherein the unstretched film has a haze value of 40% or more as measured according to JIS K 7136 (2000). 4. The intermediate layer according to any one of claims 1 to 3, wherein the intermediate layer contains 70 to 98% by weight of the propylene-based resin composition and 2 to 30% by weight of linear low-density polyethylene having a density of 0.910 or more. non-oriented film for food packaging. A food packaging bag made of the unstretched film for food packaging according to any one of claims 1 to 4, which is melt-cut and made with the sealing layer inside. 6. The food packaging bag according to claim 5, having a square bottom gusset on the bottom.

Images