JP2016032911A - Tear-directionality sealant film, and film laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tear-directionality sealant film in which heat sealing temperature is suppressed from rising, the thermal shrinkage rate of which is improved and which is obtained by uniaxial drawing to have tear directionality, and to provide a film laminate which is obtained by piling another film on the tear-directionality sealant film and has excellent tear characteristics.SOLUTION: A tear-directionality sealant film 1 includes a heat-sealable heat seal layer 20 on one side of a base material layer 10 and is obtained substantially by uniaxial drawing. Each of the base material layer and the heat seal layer contains at least one of an ethylene-propylene copolymer and an ethylene-propylene-butene copolymer. The first melting peak temperature of a resin of the base material layer is made equal to or higher than the second melting peak temperature of another resin of the heat seal layer. The temperature when the uniaxial drawing is performed is made equal to or higher than the second melting peak temperature. The heat shrinkage rate in the drawing direction is 10% or lower, the heat seal initiation temperature is 140°C or lower and the tear strength in the drawing direction is 50 N/cm or lower when tear-directionality sealant film is torn by a trouser tear method.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tear directional sealant film and a film laminate, and more particularly to a tear directional sealant film that realizes good heat sealing performance in a stretched film and a laminate that is a laminate thereof.

  Currently, in the packaging of articles, films and articles are supplied by an automatic packaging machine, and filling, packaging, and sealing are performed continuously. The performance required for such a packaging film is to have sufficient strength at the time of supply and processing of the film and further distribution and satisfy good heat sealability at the time of sealing. In addition to these requirements, easy opening is also required. An unstretched film, which is a general sealant film, is generally not stretched and therefore tends to have high tear strength as a whole. Further, in a general biaxially stretched heat seal film, the tear strength is lowered due to molecular orientation, but the directionality is not fixed. Therefore, tearing of the heat seal film is not always easy, and there are problems such as excessive resistance at the time of tearing and directionality not being determined.

  As a countermeasure against such tearability, a film formed by uniaxial stretching has been proposed (see Patent Documents 1 and 2, etc.). Patent Document 1 is a longitudinal tearable laminated film in which a film of a propylene resin having a higher melting point than that of a heat seal layer of various olefin resins is laminated and longitudinally uniaxially stretched. Patent Document 2 is a transverse tearable laminated film in which a film of a propylene resin having a higher melting point than that of a heat seal layer of various olefin resins is laminated and stretched laterally uniaxially.

  According to the films exemplified in Patent Documents 1 and 2, etc., a certain effect is exhibited in the tearability in the film direction. However, the heat seal temperature rises due to orientation by stretching. Another problem is that the thermal shrinkage rate increases depending on the direction due to the influence of orientation. Therefore, when using an existing uniaxially stretched film as a sealant film, it tends to be difficult to obtain sufficient heat seal strength.

  Thus, existing uniaxially stretched films have been required to cope with low-temperature heat sealing and to improve the stability of the shape during heating. Further, when the uniaxially stretched film is used as a so-called sealant film for the purpose of laminating another film thereon, it is more likely to become a problem.

  In particular, if heat sealing in a low temperature range is possible, improvement in productivity of sealing work by heat sealing is expected. Further, if the thermal shrinkage rate is reduced, the influence on the appearance of the seal is alleviated, and deformation that is a concern during processing is also alleviated. In view of this, there has been a demand for a film in which the heat seal temperature is further reduced in the uniaxially stretched film for sealant film and at the same time the heat shrinkage ratio is improved.

Japanese Patent No. 2518233 Japanese Patent Publication No. 8-18416

  The present invention has been proposed in view of the above situation, and in a sealant film having tear directionality by uniaxial stretching, a new tear capable of suppressing an increase in heat seal temperature and simultaneously improving the heat shrinkage rate. A directional sealant film is provided. And the film laminated body provided with the favorable tear characteristic which laminated | stacked another film on the said tear directionality sealant film is provided.

That is, the invention of claim 1 is a tear directional sealant film that is provided with a heat-sealable layer that can be heat-sealed on one side of the base material layer, and is substantially formed by uniaxial stretching. A first copolymer composition resin containing at least one of a 1 ethylene-propylene copolymer or a first ethylene-propylene-butene copolymer, wherein the heat seal layer comprises a second ethylene-propylene copolymer or a second ethylene-propylene copolymer; A second copolymer composition resin containing at least one of 2 ethylene-propylene-butene copolymers, and a first melt of the first copolymer composition resin measured in accordance with JIS K 7122 (1987) The peak temperature is equal to or higher than the second melting peak temperature of the second copolymer composition resin, and the first melting peak temperature is 130 to 150. , And the temperature at uniaxially stretching the tearing direction sealant film is the second melting peak temperature and an isothermal or hot, numerical values of the tear directional sealant film birefringence 8.0 × 10 ^-3 or more The heat shrinkage in the stretching direction of the tear direction sealant film measured in accordance with JIS Z 1712 (2009) is 10% or less, and the tear direction measured in accordance with JIS Z 1713 (2009) The heat seal initiation temperature of the heat seal layer in the adhesive sealant film is 140 ° C. or less, and the tear strength by the trouser tear method in the stretch direction of the tear direction sealant film measured according to JIS K 7128-1 (1998) The present invention relates to a tear directional sealant film characterized by having a thickness of 50 N / cm or less.

  In the invention of claim 2, the first melting peak temperature is 135 to 150 ° C., and the heat shrinkage in the stretching direction of the tear direction sealant film measured according to JIS Z 1712 (2009) is 5% or less. The tear directional sealant film according to claim 1.

  According to a third aspect of the present invention, the second copolymer composition resin contains at least one of a second ethylene-propylene copolymer or a second ethylene-propylene-butene copolymer and a propylene-butene copolymer. In the tear direction sealant film, the weight ratio of the propylene-butene copolymer in the second copolymer composition resin is 10 to 30% by weight, and measured according to JIS Z 1713 (2009). The tear-directional sealant film according to claim 1 or 2, wherein a heat seal start temperature of the heat seal layer is 120 ° C or lower.

  The invention according to claim 4 relates to the tear direction sealant film according to any one of claims 1 to 3, wherein a nucleating agent is added to the first copolymer composition resin.

  The invention according to claim 5 relates to a film laminate comprising the tear direction sealant film according to any one of claims 1 to 4 and a second stretched film.

  The invention according to claim 6 is a film in which the second stretched film is formed by uniaxial stretching or biaxial stretching in the same direction as the tear direction sealant film. The film laminate according to claim 5.

According to the tear directional sealant film according to the invention of claim 1, a tear directional sealant film having a heat-sealable heat seal layer on one side of the base material layer and substantially formed by uniaxial stretching, The base layer is a first copolymer composition resin containing at least one of a first ethylene-propylene copolymer or a first ethylene-propylene-butene copolymer, and the heat seal layer is a second ethylene- The first copolymer, which is a second copolymer composition resin containing at least one of a propylene copolymer and a second ethylene-propylene-butene copolymer, and measured according to JIS K 7122 (1987) The first melting peak temperature of the composition resin is equal to or higher than the second melting peak temperature of the second copolymer composition resin. The solution peak temperature is 130 to 150 ° C., the temperature at which the tear direction sealant film is uniaxially stretched is the same or higher temperature than the second melting peak temperature, and the numerical value of the tear direction sealant film birefringence is It is 8.0 × 10 ⁻³ or more, and the heat shrinkage rate in the stretching direction of the tear direction sealant film measured in accordance with JIS Z 1712 (2009) is 10% or less, and is in accordance with JIS Z 1713 (2009). In the tear direction sealant film measured according to the above, the heat seal start temperature of the heat seal layer is 140 ° C. or less, and the tear direction sealant film is measured according to JIS K 7128-1 (1998). Tear strength by trouser tearing in the direction is 50 N / cm or less. In the sealant film having suppress the increase of the heat-sealing temperature, it is possible to improve the heat shrinkage at the same time.

  According to the tear directional sealant film according to the invention of claim 2, in the invention of claim 1, the first melting peak temperature is 135 to 150 ° C., and the tear measured according to JIS Z 1712 (2009) Since the heat shrinkage rate in the stretching direction of the directional sealant film is 5% or less, a better seal appearance can be obtained, deformations that are a concern during processing can be improved, and better processing suitability can be obtained.

  According to the tear direction sealant film of the invention of claim 3, in the invention of claim 1 or 2, the second copolymer composition resin is a second ethylene-propylene copolymer or a second ethylene-propylene-butene. Containing at least one of the copolymers and a propylene-butene copolymer, wherein the weight proportion of the propylene-butene copolymer in the second copolymer composition resin is 10 to 30% by weight, JIS Z 1713 (2009), since the heat seal start temperature of the heat seal layer in the tear directional sealant film measured in accordance with 1713 (2009) is 120 ° C. or less, an improvement in the productivity of sealing work by heat seal is expected.

  According to the tear directional sealant film according to the invention of claim 4, in the invention of any one of claims 1 to 3, since a nucleating agent is added to the first copolymer composition resin, the resin in the layer In this case, crystallization is promoted, and a certain directionality is generated by uniaxial stretching, so that good tearing can be obtained.

  According to the film laminate of the invention of claim 5, since the tear direction sealant film according to any one of claims 1 to 4 and the second stretched film are laminated, the second stretch Functionality derived from the film can be provided.

  According to the film laminate of the invention of claim 6, in the invention of claim 5, the second stretched film is formed by substantially uniaxial stretching in the same direction as the stretching direction of the tear direction sealant film. Therefore, it is possible to provide functionality derived from the second stretched film and ease tearing as a film laminate.

It is a schematic cross-sectional schematic diagram of the tear direction sealant film of this invention. It is a schematic cross-sectional schematic diagram of the film laminated body of this invention. It is a whole perspective view of the bag-like thing created using the film laminated body of this invention.

  The schematic cross-sectional schematic diagram of FIG. 1 is an example of the structure of the tear directional sealant film 1. In the tear direction sealant film 1, a heat seal layer 20 that can be heat sealed is provided on one side (first surface 11 side) of the base material layer 10. The tear direction sealant film 1 is substantially formed by uniaxial stretching.

  In general, the stretching direction of the resin film is two types, that is, stretching in the winding direction (length direction, flow direction, MD) and stretching in the width direction (TD). Film formation with stretching in any one direction is uniaxial stretching, and film formation with stretching in both directions is biaxial stretching. On the other hand, the tear direction sealant film 1 of the present invention is uniaxially stretched only in one direction using stretching performed by a tenter. Hereinafter, in the present specification and examples, the description will be made assuming that the uniaxial stretching direction (the stretching direction (Or1) of the film) is the stretching in the transverse width direction (TD). The term “substantially” means that stretching is not actively performed in directions other than the direction of uniaxial stretching. However, stretching in other directions may be partially included as a force majeure for convenience of film formation.

  The first copolymer composition resin (D1) that forms the base layer 10 and the second copolymer composition resin (D2) that forms the heat seal layer 20 are polyolefin resins in a broad sense. The first copolymer composition resin (D1) and the second copolymer composition resin (D2) may be a single resin or a mixture of two or more kinds of resins. The properties required for each layer, physical properties necessary for the entire tear direction sealant film, and the like are taken into consideration, and the type of resin, the difference in physical properties, and the blending amount are specified. Furthermore, from the viewpoint of maintaining good adhesion between the base material layer 10 and the heat seal layer 20, the compatibility of the resins is also considered.

  The first copolymer composition resin (D1) forming the base material layer 10 contains at least one of the first ethylene-propylene copolymer (A1) and the first ethylene-propylene-butene copolymer (B1). Composition. The second copolymer composition resin (D2) forming the heat seal layer 20 is at least one of the second ethylene-propylene copolymer (A2) and the second ethylene-propylene-butene copolymer (B2). It is the composition containing this. Thus, both layers are formed from a propylene-based olefin resin. However, even if the ethylene-propylene copolymer and the ethylene-propylene-butene copolymer in each layer are the same type in form, copolymers having different physical properties are selected depending on the properties required for the layer.

  In addition, the second copolymer composition resin (D2) forming the heat seal layer 20 includes at least the second ethylene-propylene copolymer (A2) or the second ethylene-propylene-butene copolymer (B2). The composition containing either and a propylene-butene copolymer (C2) is also included. The action of the propylene-butene copolymer (C2) is to lower the heat seal start temperature of the heat seal layer 20 as disclosed in the following examples. That is, it contributes to improving the efficiency of heat sealing.

  In the first copolymer composition resin (D1) and the second copolymer composition resin (D2), the special weight ratio is not limited as long as the corresponding resin is used. However, in the composition containing the propylene-butene copolymer (C2), the weight ratio of the propylene-butene copolymer (C2) in the second copolymer composition resin (D2) is 10 to 30% by weight. It is. When the weight ratio of the propylene-butene copolymer (C2) increases so as to exceed 40% by weight, the film surface is softened and easily damaged, and the appearance of the film tends to deteriorate.

  Specific examples of the resin used are resins of the type disclosed in the examples below. In the tear directional sealant film 1, the base material layer 10 is a part that maintains the structural strength of the film, and the first copolymer composition resin (D1) that forms the base material layer 10 is mainly a film in a predetermined direction. The directionality for making it easy to tear is provided. The second copolymer composition resin (D2) forming the heat seal layer 20 is subjected to thermal fusion between the same layers. It becomes a sealing part when the tear direction sealant film 1 itself is sealed or a film laminate 5 (see FIG. 2) described later is used. Specifically, easiness of tearing and melting in a lower temperature range are required.

  Therefore, each layer together with the base layer 10 (first copolymer composition resin (D1)) and heat seal layer 20 (second copolymer composition resin (D2)) of the tear direction sealant film 1 is used. The physical properties required for the resin are as follows.

  The tendency of thermal melting of the base material layer 10 and the heat seal layer 20 can be grasped by the numerical value by measuring the melting peak temperature. Therefore, the first melting peak temperature (Tm1) of the first copolymer composition resin (D1) measured according to JIS K 7122 (1987) is the second melting peak of the second copolymer composition resin (D2). The temperature (Tm2) is isothermal or high. For the convenience of melting as the heat seal layer 20, the second copolymer composition resin (D2) needs to have a lower melting peak temperature than the first copolymer composition resin (D1). Moreover, when the propylene-butene copolymer (C2) is contained, heat sealing at a low temperature is possible even at an isothermal melting peak temperature. Therefore, isothermal melting peak temperatures are acceptable.

  In addition to the melting peak temperature of the resin, the first melting peak temperature (Tm1) is defined as 130 to 150 ° C., preferably 135 to 150 ° C. When the first melting peak temperature is lower than 130 ° C., the heat shrinkage rate becomes too large. Since there is no ethylene-propylene copolymer or ethylene-propylene-butene copolymer having a first melting peak temperature exceeding 150 ° C., the upper limit of the first melting peak temperature is reached.

  Furthermore, the heating temperature at the time of uniaxially stretching the tear direction sealant film 1 is equal to or higher than the second melting peak temperature (Tm2). The regulation of the stretching temperature is necessary to develop the low temperature heat sealability of the tear direction sealant film 1. However, in the composition containing the propylene-butene copolymer (C2), heat sealing at a low temperature is possible even at an isothermal melting peak temperature.

From the viewpoint of ensuring good tearability of the tear direction sealant film 1 and the film laminate 5 including the tear direction sealant film 1, it is necessary to determine whether the directionality of the film is good. For this reason, the value of the birefringence is effective as an index. Therefore, the birefringence value of the tear directional sealant film 1 is defined to be 8.0 × 10 ⁻³ or more. When the value of the birefringence is less than the same value, it becomes difficult to tear the film straight in a predetermined direction, as will be apparent from examples described later.

  Next, the difficulty of thermal deformation of the tear directional sealant film 1 is added to the index. That is, the heat shrinkage rate in the stretching direction (Or1) of the tear direction sealant film 1 measured according to JIS Z 1712 (2009) is specified to be 10% or less. The smaller the heat shrinkage rate, the smaller the thermal deformation of the film. In particular, it is directly related to the quality of processing in the case of laminating (laminating) another film on the tear direction sealant film 1 as in the film laminate 5. When the heat shrinkage rate exceeds 10%, the processing suitability such as heat sealing and packaging becomes extremely poor. Therefore, considering the good processing suitability, the heat shrinkage rate is suitably 10% or less, more preferably 5% or less.

  In addition, an index indicating whether the heat seal performance of the tear directional sealant film 1 is good is added. In the measurement based on JIS Z 1713 (2009), the heat seal start temperature of the heat seal layer 20 of the tear direction sealant film 1 is 140 ° C. or less, more preferably 120 ° C. or less. The lower the heat seal start temperature, the faster the melting of the resin layer in contact with the hot plate. Therefore, the time required for heat sealing is also shortened. When the heat seal start temperature is higher than 140 ° C., the heat seal itself is possible. However, since the time until the second copolymer composition resin (D2) of the heat seal layer 20 is melted becomes longer, the time required for heat seal fusion becomes longer and the heat seal portion shrinks accordingly. The appearance of the heat seal part deteriorates. Therefore, the aforementioned temperature range is appropriate in terms of continuous packaging and production efficiency. In addition, the heat resistance of the film itself, durability, etc. may be calculated | required by the usage object of the tear direction sealant film 1, and a usage condition. Thus, there is a range of suitable heat seal start temperatures depending on the purpose.

  Furthermore, the tear directional sealant film 1 itself is required to have an appropriate strength and good tear performance. Therefore, in the measurement based on JIS K 7128-1 (1998), the tear strength by the trouser tearing method in the stretching direction (Or1) of the tear direction sealant film 1 is 50 N / cm or less. If the tear strength is too large, the resistance at the time of tearing is increased, which does not meet the object of the present invention. Therefore, an appropriate tear strength range converges to 50 N / cm or less.

  The thickness of the tear direction sealant film 1 is not particularly defined. It is the same as a general film product and has a thickness of 10 to 100 μm. In this case, the ratio of the thickness of the base material layer 10 and the heat seal layer 20 is 3: 1 to 50: 1. That is, the ratio of the thickness of the base material layer 10 in the tear direction sealant film 1 is large. That is, a performance that enables straight tearing to the base material layer 10 side is required. Therefore, a nucleating agent is added to the first copolymer composition resin (D1) constituting the base material layer 10.

  By adding the nucleating agent to the first copolymer composition resin (D1), crystallization is promoted by the resin in the layer. This crystallization and uniaxial stretching causes a certain directionality in the base material layer 10. This results in good tearing. The main nucleating agents used here are as follows.

  Specific examples of saccharide nucleating agents such as sorbitol, nonitol, xylitol, etc. include bis-1,3: 2,4- (3′-methyl-4′-fluoro-benzylidene) 1-propylsorbitol, bis-1. , 3: 2,4- (3 ′, 4′-dimethylbenzylidene) 1′-methyl-2′-propenyl sorbitol, bis-1,3,2,4-dibenzylidene 2 ′, 3′-dibromopropylsorbitol, 1,2,3-trideoxy-4,6: 5,7-bis-[(4-propylphenyl) methylene] -nonitol, bis-1,3: 2,4- (5 ′, 6 ′, 7 ′, 8'-tetrahydro-2-naphthaldehyde benzylidene) 1-allylxylitol, bis-1,3: 2,4- (3 ', 4'-dimethylbenzylidene) 1-propylxylitol, and the like.

  Specific examples of the nucleating agent of the phosphate ester compound include sodium bis (4-t-butylphenyl) phosphate (including lithium phosphate and aluminum phosphate), 2,2′-methylene-bis (4 , 6-di-t-butylphenyl) phosphate sodium salt (including lithium phosphate salt and aluminum phosphate salt), bis- (4-t-butylphenyl) calcium phosphate salt, and the like.

  Furthermore, as a triaminobenzene derivative nucleating agent, there is 1,3,5-tris (2,2-dimethylpropanamide) benzene and the like. Examples of the carboxylic acid metal salt nucleating agent include sodium benzoate (including potassium salt and lithium salt), aluminum dibenzoate, and calcium 1,2-cyclohexanedicarboxylate. In the examples described later, a carboxylic acid metal salt nucleating agent was used.

  In addition to being used alone as a packaging material, the tear directional sealant film 1 described so far is mainly laminated (laminated) with other films and processed into various packaging materials. The schematic cross-sectional schematic diagram of FIG. 2 is an example of the film laminate 5. The 2nd stretched film 2 is laminated | stacked on the other side (2nd surface 12 side) of the base material layer 10 in which the heat seal layer 20 of the tear direction sealant film 1 is not provided. Thus, the film laminate 5 is formed as a combination of both films. The method for laminating the second stretched film 2 on the tear direction sealant film 1 is not limited, and a known method such as dry lamination, extrusion lamination, or hot melt lamination is employed depending on the purpose.

  The second stretched film 2 is a film formed by uniaxial stretching substantially in the same direction as the tear direction sealant film 1 or a film formed by biaxial stretching. This is because the film laminate 5 itself needs to have good tearability. In selecting the second stretched film 2, the purpose is mainly considered. For packaging materials such as bags, sufficient strength and ease of tearing in a certain direction are required. Moreover, the second stretched film 2 can have functionality such as gas barrier performance. That is, the functionality derived from another film can be provided with the lamination of the second stretched film 2.

  When the second stretched film 2 is laminated, the stretch direction of the second stretched film 2 is aligned with the stretch direction of the tear direction sealant film 1. Another film may be laminated on the outside of the second stretched film 2.

  In the tear direction sealant film 1 and the second stretched film 2 of the present invention, additives such as an antiblocking agent, an antistatic agent, an antioxidant, a neutralizing agent, and a coloring agent can be added as necessary. .

[Creation of tear direction sealant film]
For the tear direction sealant films of Prototype Examples 1 to 16, based on the blending ratio (parts by weight) of each layer shown in Tables 1 to 3 below, the raw material resin is melted and kneaded to form a co-extrusion T-die film. Using a machine and an oven, the film was substantially uniaxially stretched in the transverse direction (TD). Regarding the raw materials used, the blending ratio is 100% by weight in total in each layer of the base material layer and the heat seal layer. In each prototype, the film thickness after stretching was controlled under the condition of 40 μm. The ratio of the layer thickness of the base material layer and the heat seal layer was approximately 10: 1. Furthermore, the second stretched film described later was laminated on the tear direction sealant film of each prototype example by dry lamination to obtain a film laminate.

[Raw materials]
The following raw materials were used as the raw material resin for forming each layer.
(Raw material 1) Ethylene-propylene copolymer (Nippon Polypro Co., Ltd., trade name “WEG5A”, melting peak temperature 143 ° C.)
(Raw material 2) Ethylene-propylene copolymer (manufactured by Nippon Polypro Co., Ltd., trade name “EG6D”, melting peak temperature 139 ° C.)
(Raw material 3) Ethylene-propylene copolymer (melting peak temperature 130 ° C., MFR7)
(Raw material 4) Ethylene-propylene-butene copolymer (manufactured by Nippon Polypro Co., Ltd., trade name “FX8877”, melting peak temperature 132 ° C.)
(Raw material 5) Ethylene-propylene copolymer (manufactured by Nippon Polypro Co., Ltd., trade name “WFX4”, melting peak temperature 125 ° C.)
(Raw material 6) Ethylene-propylene-butene copolymer (manufactured by Nippon Polypro Co., Ltd., trade name “FX4G”, melting peak temperature 126 ° C.)
(Raw material 7) Propylene-butene copolymer (Mitsui Chemicals, trade name “Tuffmer XM7070”, melting peak temperature 75 ° C.)
(Raw material 8) Ethylene-propylene copolymer (manufactured by Nippon Polypro Co., Ltd., trade name “WFX6”, melting peak temperature 125 ° C.)
(Raw material 9) Ethylene-propylene-butene copolymer (manufactured by Nippon Polypro Co., Ltd., trade name “FW4B”, melting peak temperature 138 ° C.)

The following raw materials were also used as other ingredients.
As the nucleating agent, a carboxylic acid metal salt nucleating agent manufactured by Milliken Japan GK was used.
As an antiblocking agent, powdered synthetic silica (manufactured by Fuji Silysia Chemical Ltd., trade name “Silysia 430”) was used.
As the antistatic agent, Toho Chemical Industries, Ltd., trade name “Anstex SA-300F” was used.
In addition, about antiblocking agent and antistatic agent, since it is trace amount, it has not described in the table | surface.

The following three types were used as the second stretched film laminated with the tear direction sealant film of each prototype.
(Film 1) Polypropylene film formed by uniaxial stretching (Futamura Chemical Co., Ltd., trade name “FOR-M-TC # 30”, thickness 30 μm)
(Film 2) Polypropylene film formed by biaxial stretching (Futamura Chemical Co., Ltd., trade name “FOS # 40”, thickness 40 μm)
(Film 3) Polyethylene terephthalate film (Futamura Chemical Co., Ltd., trade name “FE2001 # 12”, thickness 12 μm)

[Melting peak temperature]
The melting peak temperature of each resin used was measured according to JIS K 7122 (1987). In the case where there is only one kind of resin constituting the base material layer or the heat seal layer, the standard value of the raw material resin is used. When the resin constituting the base material layer or the heat seal layer is a mixture of two or more types, a differential scanning calorimeter (DSC) “Q2000” manufactured by TI Instrument Japan Co., Ltd. conforming to the standard. Was used to measure the melting peak temperature.

[Stretching temperature]
The temperature of the oven when stretching using a tenter was defined as the temperature during stretching.

[Heating shrinkage]
With respect to the tear direction sealant films of Prototype Examples 1 to 16, the heat shrinkage rate was measured based on the method and conditions based on JIS Z 1712 (2009). At the time of measurement, the longitudinal direction of the measurement piece (width 20 mm, length 150 mm) was taken as the film stretching direction, that is, the lateral width direction in all of the tear direction sealant films of the prototypes. Therefore, the heat shrinkage rate was calculated from the change in length before and after heating.

[Heat seal start temperature]
The tear direction sealant films of Prototype Examples 1 to 16 were measured according to JIS Z 1713 (2009). At this time, the longitudinal direction of the measurement piece (width 50 mm, length 250 mm) was taken as the film winding direction. Then, the heat seal layers of the two test pieces are overlapped with each other, and a heat inclination tester (heat seal tester) manufactured by Toyo Seiki Seisakusho Co., Ltd. is used. The heat seal pressure is 1 kg / cm ² and the heat seal time is 1 Seconds. And it heat-sealed on the conditions which incline (heat-up) temperature at 5 degreeC steps. At this time, a PET film (thickness: 12 μm) for preventing fusion was sandwiched between the heat plate of the heat sealer and the test piece film. The test piece fused by heat sealing was opened at 180 °, and the unsealed portion was pulled with a tensile tester (Strograph E-L) manufactured by Toyo Seiki Seisakusho. And the temperature when the heat seal strength reached 3N was determined.

[Measurement of birefringence]
A polarizing microscope (manufactured by Olympus Corporation, trade name “BX51TRF-6”, light source: white light) was adjusted to a state orthogonal to the polarization axis direction of the polarizer (polarizer) and the analyzer (analyzer). The tear direction sealant films of Prototype Examples 1 to 16 cut to 5 cm square were placed on the sample stage. The sample stage was rotated so that the field of view became the darkest (quenching position). Thereafter, the sample stage was rotated 45 ° to the right or left from the extinction position. A Berek type compensator (Olympus Co., Ltd., trade name “U-CBE”) was inserted, and the knob of the compensator was appropriately operated from the 30 ° position to read the reference scale angles (a, b). Therefore, the value of “i” was calculated from “i = (a−b) / 2”. Retardation was determined from the value of “i” using the angle-retardation conversion table attached to the compensator. Then, the birefringence was calculated by dividing by the thickness of the sample film. The birefringence was measured at 23 ± 5 ° C.

[Measurement of tear strength]
In accordance with the trouser tear method prescribed in JIS K 7128-1 (1998) for the tear directional sealant film of each prototype or a film laminate in which the second stretched film is laminated on the tear directional sealant film by dry lamination. the tear strength S _T in the width direction of the film (TD) was measured Te. In the film to be measured for carrying out the trouser tear method, a test piece having a length of 150 mm in the transverse direction TD, which is the stretching direction, and a test piece having a length of 50 mm in the longitudinal direction MD perpendicular to the stretching direction is cut out, and 75 mm in the longitudinal direction of the test piece. notched, by pulling both pieces portion in directions opposite to each other were measured load (N) (tear strength S _T of the horizontal width direction TD) (N / cm). For prototype example 1, three layers of films 1, 2, and 3 were laminated, and for other prototype examples, only film 1 was laminated.

[Evaluation of film appearance]
The surface of the tear direction sealant film was visually observed, and an example having no problem in transparency and smoothness was evaluated as “A”. An example in which scratches or unnatural patterns appeared on the film surface was evaluated as “B”.

[Evaluation of processing suitability]
When the tear direction sealant film and the second stretched film of each trial example were laminated by dry lamination using a known apparatus, an example that could be processed smoothly without problems was evaluated as “A”. On the other hand, an example in which a failure occurred midway and the smooth machining was not achieved was evaluated as “B”.

[Evaluation of packaging suitability]
About the film laminated body produced by dry laminating the tear direction sealant film of each trial example and the second stretched film (the above-mentioned film 1), heat sealing is performed using an automatic packaging machine (manufactured by Fujikikai Co., Ltd., FW3400). Thus, a horizontal pillow was made into a bag-like material (opening width of about 100 mm, bag length of about 200 mm). The heat seal temperature was set to 140 ° C. as the bag making condition for the horizontal pillow.

  FIG. 3 is an overall perspective view showing an outline of the bag-like object 50. Reference numerals 51 and 52 are sealing portions, 53 is a center seal portion, 54 is a main body portion, and C is a content. MD in a figure is a winding direction. TD is a direction perpendicular to the film winding direction, and is the film stretching direction.

  In the pseudo heat-sealing packaging using the above automatic packaging machine, an example in which heat sealing was possible smoothly at a speed higher than the initially set speed was evaluated as “AA”. An example in which heat sealing was possible smoothly at the initial set speed was evaluated as “A”. An example in which a defect occurred during heat sealing was evaluated as “B”.

[Evaluation of straight cut performance]
<Cutability of tear direction sealant film alone>
About the tear direction sealant film of each prototype, a 5 mm cut was made along the uniaxial stretching direction of the film from the end. Tearing was performed while changing the angle in the range of 0 ° to 60 ° from the cut. That is, if a straight cut is generated even when the film is torn at a larger angle, it can be said that the straight cut property of the film is high.

  An example of being able to tear in a substantially straight line along the stretching direction in the range of 0 ° to 60 ° from the cut was evaluated as “AA”. Example of being able to tear almost linearly along the stretching direction in the range of 0 ° to 45 ° from the cut, but not able to tear almost linearly along the stretching direction in the range of 45 ° to 60 ° Was evaluated as “A”. An example in which the film could not be torn substantially linearly along the stretching direction even at 0 ° from the notch was evaluated as “B”.

<Cutability of film laminate>
A film laminate was prepared by dry laminating the tear directional sealant film of each prototype and the second stretched film (the above-mentioned film 1). A horizontal pillow bag was made under the same conditions as in the evaluation of the packaging suitability described above to produce a similar bag-like product. A 5 mm cut was made in the sealing part of the bag-like material (see FIG. 3) in the same direction as the uniaxial stretching direction of the tear direction sealant film (direction of TD in the drawing). An example in which the film laminate was torn almost straight from the notch was evaluated as “A”. An example in which the film laminate was torn without directionality from the cut (including cases where it was difficult to tear) was evaluated as “B”. In this evaluation, judgment was made by visual observation and feel when torn.

[Comprehensive evaluation]
Based on the measurement results of each numerical value and various evaluation results, the tear direction sealant film of the prototype was comprehensively evaluated in four stages including the possibility of commercialization such as actual productivity. A tear direction sealant film that is excellent in all indicators was rated as “excellent”. A generally good tear direction sealant film was defined as “good”. A tear directional sealant film that has no problem in use was evaluated as “OK”. The tear direction sealant film which cannot be used was made "impossible".

Tables 1 to 3 show the materials used, the measurement results, and the evaluation results of each prototype. The raw material used in order of the base material layer (10) and the heat seal layer (20) and the weight blending ratio (parts by weight, weight percent) for each layer are shown. The first melting peak temperature (° C.) of the resin of the base layer, the second melting peak temperature (° C.) of the resin of the heat seal layer, the stretching temperature (° C.) during film formation, the heat shrinkage rate (%), the heat Seal start temperature (° C.), birefringence (number in table × 10 ⁻³ ), tear direction sealant film alone (N / cm), film laminate tear strength (N / cm) Indicates the measured value.

  Along with this, film appearance (two-step evaluation), processing suitability (two-step evaluation), packaging suitability (three-step evaluation), straight-cut property of tear direction sealant film (three-step evaluation), straight-cut property of film laminate The order is (two-step evaluation) and comprehensive evaluation (four-step evaluation). In the table, “-” indicates unmeasured and not implemented.

[Results and Discussion]
Prototype examples 1 to 12 were excellent, good, and good. However, Prototype Examples 13 to 16 are not possible and practically unsuitable for use. In all prototypes, the composition resin of the base material layer and the heat seal layer is basically a composition containing at least one of an ethylene-propylene copolymer and an ethylene-propylene-butene copolymer. However, even if the same kind of resin is used, the performance of the tear-direction sealant film produced by the physical properties of the resin itself is greatly different. Therefore, the results, raw materials, and physical properties to be provided will be examined below.

<Melting peak temperature>
The first melting peak temperature on the base material layer side of Prototype Example 13 was less than 130 ° C. In Prototype Example 13, the base material layer portion that occupies most of the tear directional sealant film was easily softened at a relatively low temperature, and the numerical value of the heat shrinkage ratio was large. This leads to a decrease in the heat resistance of the film. Therefore, the first melting peak temperature needs to be 130 ° C. or higher in consideration of thermal stability. In addition, it was impossible to obtain an ethylene-propylene copolymer or an ethylene-propylene-butene copolymer having a first melting peak temperature exceeding 150 ° C. Therefore, the upper limit is set to 150 ° C. as a practically manufacturable range with reference to 143 ° C. disclosed in Prototype Example 1 and the like.

  Prototype Example 14 is an example in which the second melting peak temperature on the heat seal layer side is higher than the first melting peak temperature. For this reason, the rise of the heat seal start temperature is remarkable, and the productivity at the time of subsequent processing is lowered. Therefore, it is desirable that the first melting peak temperature and the second melting peak temperature are isothermal or the first melting peak temperature side is high.

<Extension temperature>
Prototype Example 15 is an example in which the stretching temperature is lower than the second melting peak temperature. In this prototype, the heat seal start temperature increased. Therefore, it is desirable that the temperature at the time of stretching is equal to or higher than the second melting peak temperature in view of the productivity of post-processing.

<Birefractive index>
According to Prototype Example 16, the stretching temperature is higher than the melting peak temperature of the base material layer. For this reason, the numerical value of the birefringence decreased due to the influence of the orientation of the resin, and the numerical value of the tear strength increased. And the straight cut performance also deteriorated. In contrast to other prototypes, the birefringence value is considered to be 8.0 × 10 ⁻³ or more.

<Heating shrinkage>
According to the above prototype examples 1 to 12, except for the impossible prototype examples 13 to 16, the heat shrinkage rate in the stretching direction was 10% or less. Therefore, a heat shrinkage rate of 10% or less is an index for distinguishing good examples. More preferably, it is 5% or less from Prototype Example 10, and more preferably 3% or less from Prototype Examples 1, 2, 4, 5, 6, 7, and 8.

<Heat seal start temperature>
According to the above prototype examples 1 to 12, except for the prototype examples 13 to 16, which were impossible, the heat seal starting temperature was 140 ° C. or lower. Therefore, the heat seal start temperature of 140 ° C. or lower is an index for distinguishing good examples. More preferably, it is 120 ° C. or lower than that of Prototype Example 10, and even more preferably, it is 100 ° C. or lower than that of Prototype Examples 4, 5, 6, 7, and 9.

<Tear strength>
According to the above prototype examples 1 to 12, except for the impossible prototype examples 13 to 16, the tear strength in the stretching direction of the tear direction sealant film was 50 N / cm or less. Therefore, a tear strength of 50 N / cm is an index for distinguishing a good example. There is no specific lower limit.

<Composition and ratio of propylene-butene copolymer>
Prototype Examples 4, 5, 6, 7, 9, 10, and 12 are examples in which a propylene-butene copolymer is further contained in the composition resin of the heat seal layer. A tendency common to the examples is that the heat seal start temperature has decreased as compared to other prototypes. From this, considering the improvement of the processing capability of the heat seal process, it is significant to contain the propylene-butene copolymer in the heat seal layer. However, when the blending ratio of the propylene-butene copolymer is excessive, the balance in the resin may be affected. For example, when the blending ratio of the propylene-butene copolymer of Prototype Example 7 was increased, the film surface was softened and thus was easily damaged. If it does so, a fixed upper limit will be drawn in the case of a compounding from harmony of beautiful appearance and simple heat seal nature. Therefore, the blending ratio of the propylene-butene copolymer in the second copolymer composition resin forming the heat seal layer is suitably in the range of 10 to 30% by weight.

<With / without nucleating agent>
Prototype examples 1, 4, 5, 6, 7, and 8 are examples in which a nucleating agent is added to the base material layer. As a tendency common to the examples, an improvement in straight-cut performance was clarified. With the addition of the nucleating agent, crystallization is promoted by the resin in the base material layer during uniaxial stretching. That is, it is considered that a certain directionality occurs in the stretching direction, and the tearing quality is further improved. This property is the most needed property in tear directional sealant films. Therefore, the effect of adding the nucleating agent to the resin of the base material layer is great.

<Lamination of second stretched film>
When a film laminate was prepared using a trial example excellent in straight cut performance of a tear direction sealant film alone, the laminate also showed good straight cut performance as a whole. For this reason, a tear direction sealant film is effective also as a packaging material which shows a good tear independently. In addition, even when other films were laminated, the film laminated body exhibited good tear without disturbing the entire tear of the film laminate. That is, even if the other second film to be laminated has poor heat seal properties, the tear direction sealant film has good heat seal properties, so both layers can provide good heat seal performance and tearing convenience. Can have both.

  As described above, the tear-directional sealant film including the elements defined in the present invention has good tearability and heat sealability. Furthermore, by laminating the tear direction sealant film with another stretched film, heat sealing performance is also provided while maintaining tearability. For this reason, the versatility of packaging materials for various articles is extremely high.

DESCRIPTION OF SYMBOLS 1 Tear direction sealant film 2 2nd stretched film 5 Film laminated body 10 Base material layer 11 The 1st surface of the tear direction sealant film 12 The 2nd surface of the tear direction sealant film 20 Heat seal layer MD Tear direction sealant film Longitudinal direction (winding direction)
TD direction (width direction, stretching direction) orthogonal to the stretching direction of the tear direction sealant film

Claims (6)

A tear direction sealant film (1) provided with a heat sealable layer (20) capable of heat sealing on one side of a base material layer (10) and substantially formed by uniaxial stretching,
The base material layer is a first copolymer composition resin (D1) containing at least one of a first ethylene-propylene copolymer (A1) or a first ethylene-propylene-butene copolymer (B1);
The heat seal layer is a second copolymer composition resin (D2) containing at least one of the second ethylene-propylene copolymer (A2) or the second ethylene-propylene-butene copolymer (B2),
The first melting peak temperature (Tm1) of the first copolymer composition resin measured according to JIS K 7122 (1987) is isothermal with the second melting peak temperature (Tm2) of the second copolymer composition resin. Or while being high temperature, the said 1st melting peak temperature is 130-150 degreeC,
The temperature when uniaxially stretching the tear direction sealant film is isothermal or high with the second melting peak temperature,
The value of the birefringence of the tear direction sealant film is 8.0 × 10 ⁻³ or more,
The heat shrinkage rate in the stretching direction (Or1) of the tear direction sealant film measured according to JIS Z 1712 (2009) is 10% or less,
The heat seal start temperature of the heat seal layer in the tear direction sealant film measured according to JIS Z 1713 (2009) is 140 ° C. or less,
A tear direction sealant having a tear strength by a trouser tear method in the stretching direction (Or1) of the tear direction sealant film measured according to JIS K 7128-1 (1998) is 50 N / cm or less. the film. The first melting peak temperature is 135 to 150 ° C,
The tear direction sealant film according to claim 1, wherein the heat shrinkage rate in the stretching direction of the tear direction sealant film measured in accordance with JIS Z 1712 (2009) is 5% or less. The second copolymer composition resin comprises at least one of a second ethylene-propylene copolymer (A2) or a second ethylene-propylene-butene copolymer (B2), a propylene-butene copolymer (C2), and Containing
The weight ratio of the propylene-butene copolymer (C2) in the second copolymer composition resin is 10 to 30% by weight,
The tear direction sealant film according to claim 1 or 2, wherein a heat seal initiation temperature of the heat seal layer in the tear direction sealant film measured in accordance with JIS Z 1713 (2009) is 120 ° C or lower.   The tear direction sealant film according to any one of claims 1 to 3, wherein a nucleating agent is added to the first copolymer composition resin.   A film laminate (5) comprising the tear direction sealant film according to any one of claims 1 to 4 and a second stretched film (2).   6. The film according to claim 5, wherein the second stretched film is a film formed by uniaxial stretching or a film formed by biaxial stretching in the same direction as the stretching direction of the tear direction sealant film. Film laminate.

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