JP2009214941A - Manufacturing method for food package bag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a food package bag that can be manufactured at a high speed by a packaging machine and can well store foods such as snack confectionery requiring oxygen barrier characteristic and water vapor barrier characteristic. <P>SOLUTION: The food package bag comprises a sealant layer (A)1 made of a molten composite having a low melting point polyolefin resin and a polyester resin, a vapor deposition layer (B)2 and a biaxially stretched polyester film layer (C)3 laminated in this sequence, and the layer (A)1 is placed inside the bag. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a food packaging bag that requires an oxygen barrier and a water vapor barrier, such as a snack confectionery bag such as potato chips.

  Conventional snack confectionery bags generally have a packaging material composition from the inside of polypropylene resin layer / polyethylene resin layer / metal aluminum vapor deposition / biaxially stretched PET (polyethylene terephthalate) layer / polyethylene resin layer / biaxially stretched polypropylene resin. Many have a six-layer structure, or a four-layer structure of polypropylene resin layer / metal aluminum vapor deposition / polyethylene resin layer / biaxially stretched polypropylene resin layer.

  The innermost polypropylene resin (PP) layer serves as a sealant. For the innermost layer, polypropylene resin is used because heat sealing is possible at a low temperature and hot tack property immediately after sealing is required. The hot tack property is necessary because air pressure or nitrogen is sealed in the bag and the bag is inflated in order to prevent breakage of the snack that is the contents of the bag. The thickness of the innermost polypropylene resin layer is often set to about 20 to 50 μm.

  The metal aluminum vapor deposition layer plays the role which blocks the light ray from the outside, and the role which prevents permeation of oxygen and water vapor. Its thickness is about 300 to 1500 mm, and it is usually deposited on a biaxially stretched PET film or a polypropylene resin film. The biaxially stretched PET film is a material that can deposit metal aluminum most stably, and a thickness of 12 μm is often used.

  The polyethylene resin (PE) layer is a laminate of a biaxially stretched PET film and an outermost biaxially stretched polypropylene resin (OPP) film, or an innermost unstretched polypropylene resin (CPP) film and a biaxially stretched PET film. It plays the role of an adhesive that attaches and has a thickness of about 15 μm. An ethylene- (meth) acrylic acid copolymer may be used as the polyethylene resin layer, and a urethane-containing adhesive or a monomer-containing adhesive that does not contain an organic solvent may be used instead of the polyethylene resin layer. is there.

  The OPP film constituting the outermost layer directly hits a heated heat seal member (seal bar) and plays a role of transmitting the heat to the innermost polypropylene resin layer, and has a thickness of about 15 to 20 μm. The packaging material for a snack cake bag having a 4-6 layer structure as described above has a total thickness of about 40-117 μm.

  As a processing method of the packaging material having the above-mentioned structure, from the cost aspect, while laminating while extruding PE between the vapor deposition surface of the PET film having a metal vapor deposition layer formed on one side and the unstretched PP film, In many cases, a processing method is employed in which PE is extruded and laminated between a non-deposited surface and a biaxially stretched film (OPP film).

  Due to recent demands for improving production efficiency, speeding up of packaging machines is required. In order to produce food packaging bags at high speed, it is necessary to perform heat bonding with a shorter sealing time. For this purpose, in order to apply a certain amount of heat, inevitably heat sealing at a high temperature in a short time is required. Necessary. Therefore, in order to give the amount of heat that was applied to the conventional sealing time in a short time, the sealing temperature must be higher. However, in the conventional packaging material configuration, the melting point difference between the innermost layer and the outermost layer is small. There was a problem that could not be sealed at high temperature. In particular, conventionally, since an OPP film is used for the outermost layer, there has been a problem that if the temperature exceeds a certain level, the surface is thermally contracted and the commercial value is lost.

  Furthermore, when vapor deposition is performed not on a highly heat-resistant PET film but on a film made of a plastic material having low heat resistance such as polypropylene resin or polyethylene resin, vapor deposition is performed at a high temperature in a vapor deposition furnace. However, since the film is drawn out → deposited → wound while applying tension in the high temperature atmosphere, the film itself is extended by the tension at the time of winding, and there is a problem that a crack occurs in the deposited layer.

  In general, various plastics are used for food packaging bags such as snack confectionery bags, but recently, from the viewpoint of resource conservation and environmental conservation, it is necessary to recycle used plastic products collected from the factory production process and general consumer market. The need for use is recognized worldwide, and reuse of polyester is also being considered.

  Therefore, an object of the present invention is to satisfy the functions (barrier properties, high-speed productivity, etc.) required to solve the above-mentioned problems, and to enable high-speed bag making with a packaging machine, such as an oxygen barrier property and a water vapor barrier such as snacks. An object of the present invention is to provide a food packaging bag capable of satisfactorily preserving foods requiring properties. Furthermore, it is one of the objects of the present invention to enable reuse of the collected material as a packaging material forming material.

  In the present invention, a sealant layer (A) formed from a melt composition composed of a low melting point polyolefin resin and a polyester resin, a vapor deposition layer (B), and a biaxially stretched polyester film layer (C) are laminated in this order. The packaging material is a food packaging bag formed so that the layer (A) is on the inside of the bag. The present invention is described in detail below.

  ADVANTAGE OF THE INVENTION According to this invention, the food packaging bag which can favorably preserve | save the food which requires oxygen barrier property and water vapor | steam barrier properties, such as snack confectionery which can be bag-made at high speed with a packaging machine, can be provided.

2 is a schematic diagram illustrating a configuration of a packaging material manufactured in Example 1. FIG. 6 is a schematic diagram showing a configuration of a packaging material produced in Example 2. FIG. It is explanatory drawing of the fin seal of pillow packaging.

  The food packaging bag of the present invention comprises a sealant layer (A) formed from a melt composition comprising a low melting point polyolefin resin and a polyester resin, a vapor deposition layer (B), and a biaxially stretched polyester film layer (C). Are formed using packaging materials laminated in this order.

The sealant layer (A) is formed from a molten composition composed of a low melting point polyolefin resin and a polyester resin, and is the innermost layer of the food packaging bag of the present invention.
The low melting point polyolefin resin used in the layer (A) preferably has a melting point of 120 ° C. or less in order to realize high speed productivity. Such low melting point polyolefin resin is not particularly limited, and examples thereof include polyethylene, polypropylene, ethylene-propylene copolymer, and mixtures thereof.

  The low melting point polyolefin resin is preferably a single site polyolefin resin using a single site catalyst, more preferably a metallocene polyolefin resin using a metallocene catalyst, particularly a metallocene linear low density polyethylene (metallocene LLDPE). Metallocene polyethylene or metallocene polypropylene such as

  The sealant layer (A), which is the innermost layer of the food packaging bag of the present invention, has high-speed productivity, that is, it can be stably sealed with a high-speed packaging machine, and the recent barrier-free, universal design. In order to satisfy these functions, easy peel properties are required, and when foods containing fats and oils such as potato chips and snacks are packaged, a function such as oil resistance is required.

  As a result of the inventor's earnest research to satisfy these functions, particularly excellent results were obtained by using single-site LLDPE. This single-site LLDPE is produced by an innovative polymerization technique among polyethylene production techniques. The Ziegler catalyst used in the conventional production technique is a multi-site catalyst having many kinds of active sites, and the molecular weight distribution and comonomer distribution of the produced polymer tend to be wide. In contrast, single-site LLDPE can produce a homogeneous polymer with a narrow molecular weight distribution and comonomer content distribution, and a film satisfying the required functions. Single-site LLDPE is a very clean and environmentally friendly polymer because it does not contain a halogen compound such as chlorine.

  As the metallocene LLDPE, for example, a trade name “Harmolex” manufactured by Nippon Polyolefin Co., Ltd. is commercially available, and as a film made of the metallocene LLDPE, for example, HR series manufactured by KEF Film Co., Ltd. “TUX” manufactured by Nimura Chemical Co., Ltd., “LL-X” manufactured by Nimura Chemical Co., Ltd., “Suzuron-L” manufactured by Aicero Chemical Co., Ltd., and the like are commercially available.

  The polyester resin used for the layer (A) is not particularly limited. For example, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene-2,6-naphthalate (PEN), or a copolymer thereof. An aromatic polyester such as Among them, polyethylene terephthalate (PET) resin is preferable because it is mass-produced worldwide. In addition, biodegradable aliphatic polyesters such as polycaprolactone, polyethylene-succinate, polybutylene-succinate, polybutylene-succinate-adipate, and polylactic acid are also used as a material for forming the layer (A).

  The molten composition for forming the layer (A) is preferably formed by adding a compatibilizing agent or contains a polyester-polyolefin block copolymer. In forming the layer (A), even if the low melting point polyolefin resin and the polyester resin are simply blended and melted, the mixed state is poor, phase separation occurs, and a uniformly mixed molten composition is obtained. I can't. The compatibilizer increases the compatibility between the polyester and the polyolefin, and realizes a uniform melt-mixed state. In the molten composition homogenized using the compatibilizing agent, the low-melting-point polyolefin resin and the polyester resin have a sea-island structure with small islands and are uniformly dispersed.

  The state in which the polyester and the polyolefin form a micro-dispersed sea-island structure can also be realized by containing a polyolefin-polyester block copolymer. In this case, a block copolymer may be formed by introducing a chemical bond between the low-melting-point polyolefin resin and the polyester resin constituting the layer (A), or a block copolymer may be added separately. .

  As the compatibilizing agent, any known reactive or non-reactive compatibilizing agent may be used as long as it is capable of microdispersing the polyester resin and the polyolefin resin at least in a sea-island shape while taking advantage of the characteristics of both resins. Can do. For example, ethylene- (meth) acrylic acid copolymer, metal ion cross-linked structure (ionomer) of ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester-glycidyl (meth) acrylate copolymer An ethylene- (meth) acrylic acid ester copolymer, or a block copolymer composed of a styrene-ethylene-butadiene copolymer block having a carboxyl group or a derivative thereof and a styrene polymer block is preferred.

As a compounding ratio of each component in the molten composition forming the layer (A), the polyolefin resin is 5 to 50% by weight, the polyester resin is 50 to 95% by weight, and the compatibilizer is 2 to 20% by weight. Is preferred. If the polyolefin resin is less than 5% by weight, sufficient sealability may not be obtained, and if it exceeds 50% by weight, the adhesion to the polyester substrate layer becomes poor. Further, if the compatibilizer is less than 2% by weight, the mixed state of the polyolefin resin and the polyester resin may be insufficient, and even if added in excess of 20% by weight, the effect of further improving the mixed state is recognized. I can't.

  The polyolefin-polyester block copolymer is formed by, for example, heating a polyester resin and a carboxylic acid-modified polyolefin in the presence of a bifunctional or trifunctional epoxy compound as disclosed in JP-A-2001-122955. The block copolymer etc. which were made are mentioned. Modification of the polyester resin with the polyfunctional compound will be described later. When the polyolefin-polyester block copolymer is melted, since the polyester and the polyolefin are chemically bonded, the mixed state is very good. When a polyolefin resin is further added to the block copolymer, a micro-dispersed sea island state is obtained.

  The molten composition forming the layer (A) preferably has a heat sealing property at 120 ° C. or lower. This enables high-speed bag making in combination with the outermost layer being a biaxially stretched polyester film layer having high heat resistance.

The sealant layer (A) is preferably made of a substantially unoriented film formed without performing a stretching treatment. In general, stretching of plastic is performed by stretching in the longitudinal and transverse biaxial directions at a temperature lower by 10 to 20 ° C. than the melting point, and then heat-setting, but the stretched film is lower than the unstretched film. Each of the O ₂ barrier properties and the like is improved about three times, and these physical properties are maintained up to the heat setting temperature. However, when the temperature is higher than the heat-fixed temperature, the orientation due to stretching is disturbed and shrinkage occurs, and in heat sealing, the heat sealing part becomes wrinkled, resulting in an unsatisfactory heat sealing. Therefore, the sealant layer (A) is preferably made of a substantially unoriented unstretched resin film formed without performing a stretching treatment.

  For the sealant layer (A), a resin kneaded with additives as appropriate in order to impart hot tack property and antistatic property may be used.

  The thickness of the sealant layer (A) is preferably 2 to 20 μm in both cases of a single layer or two or more layers. If the thickness is less than 2 μm, the thickness necessary for sufficient sealing cannot be maintained due to uneven thickness at the time of molding, and the fluid may flow due to high pressure at the time of sealing, so that the sealing performance cannot be maintained. On the other hand, when the thickness exceeds 20 μm, the thickness of the entire packaging material increases, and pinholes are likely to occur at the overlapping portion between the vertical seal and the horizontal seal during sealing. More preferably, it is 3-10 micrometers.

  The sealant layer (A) is composed of a molten composition in which a low-melting-point polyolefin resin and a polyester resin form a micro-dispersed sea-island structure. Therefore, the low-melting-point polyolefin resin has high sealant properties and hot tack properties, and a polyester resin. It has both high heat resistance and fragrance retention. In particular, when metallocene polyethylene or metallocene polypropylene is used as the polyolefin resin, it has low-temperature sealing properties, food safety, and oil resistance. By setting the sealant layer (A) to the inside of the bag, the food packaging bag of the present invention can be made at a high speed, and at the same time, can be preserved without skipping flavors such as potato chips and snacks.

  Furthermore, the sealant layer (A) has a high affinity for both the polyolefin resin and the polyester resin, and even when it is laminated with a layer made of different materials, it can obtain a very good interlayer adhesive strength. it can. Usually, as the sealant layer (A), an unstretched / highly stretched film is used. However, if the adhesive strength between the sealant layer (A) and the other layers as the base material is poor, the sealant layer ( A) and the layer serving as the base material are peeled off, and the layer serving as the base material breaks immediately. However, since only the sealant layer extends following the spread of the opening, there is a problem that it is difficult to open the sealant. However, in the present invention, since the adhesive strength between the sealant layer (A) and the base layer is extremely excellent as described above, the sealant layer (A) is not separated from the other layers when the bag is opened. Since it breaks, there is an effect that opening is facilitated.

  The vapor deposition layer (B) is a barrier layer having an oxygen barrier property and a water vapor barrier property. As such a vapor deposition layer (B), the metal vapor deposition layer and ceramic vapor deposition layer which vapor-deposit metal and / or a ceramic are mentioned, for example.

As the vapor deposition layer (B), SiOx, alone deposition layer of _Al 2 _{O 3} or Al, _{or, SiOx / Al 2 O 3,} SiOx / ZnO, SiOx / CaO, SiOx / B 2 O 3, CaO / Ca A binary vapor deposition layer made of (OH) ₂ is used. As the SiOx, for _{example, SiO 2, SiO 1.8, SiO} 1.6 , and the like. Especially, it is preferable to form from metal aluminum, aluminum oxide, or silicon oxide.

  In the case where a metal detector or the like is used in order to find out contamination of foreign matters in advance, a ceramic vapor deposition layer is preferable as the vapor deposition layer (B). By performing ceramic vapor deposition, it is possible to inspect even a foreign object detector that could not be performed by conventional metal vapor deposition using a metal detector.

  The thickness of the vapor deposition layer (B) is preferably 300 to 1500 mm. If the thickness is less than 300 mm, uniform vapor deposition is difficult. If the thickness exceeds 1500 mm, the thickness of the entire packaging material increases, and pinholes are likely to occur at the overlap between the vertical seal and the horizontal seal during sealing.

  The said vapor deposition layer (B) is obtained by vapor-depositing a metal and / or a ceramic on a base material. For this reason, as the film constituting the substrate, a film having heat resistance sufficient to withstand the heat history during vapor deposition is preferable, and the biaxially stretched polyester film layer (C) may be used as the substrate. Separately, a layer (E) made of a polyester resin may be provided as a base material for the vapor deposition layer (B). In this case, in the obtained food packaging bag, a layer (E) made of a polyester resin is formed between the layer (A) and the layer (B).

  Although it does not specifically limit as a polyester resin used by the said layer (E), It is preferable to use a recycled resin from consideration to an environment. The recycled resin is not particularly limited. For example, it is preferable to use a polyester resin with improved molding processability with an increased molecular weight and molecular weight distribution using a polyester resin having a relatively low molecular weight such as a recovered polyester resin as a raw material. As such a resin, a modified polyester resin (X) modified with a polyfunctional compound can be used. Such a modified polyester resin can also be used as a resin constituting the layer (C).

  As said modified polyester resin (X), the resin obtained by mix | blending a specific epoxy compound and a coupling reaction catalyst as a multifunctional compound with saturated polyester, and heat-melting is mentioned, for example. More specifically, (a) 100 parts by weight of a linear saturated polyester, (b) 0-100% by weight of a compound containing 2 epoxy groups in the molecule as a polyfunctional compound, and 3 or more epoxy groups A compound composed of 0.3 to 10 parts by weight of a mixture containing 100 to 0% by weight of a compound containing (a) and (c) 0.01 to 5 parts by weight of a binding reaction catalyst, and a temperature not lower than the melting point of the linear saturated polyester. A resin obtained by heating at a temperature can be used (see International Publication No. WO98 / 44019).

  The linear saturated polyester is preferably a polyethylene terephthalate aromatic polyester having an intrinsic viscosity of 0.50 to 0.90 dl / g, and is a recycled product of the recovered polyethylene terephthalate aromatic polyester molded product. Is preferred.

Among the polyfunctional compounds, examples of the compound containing two epoxy groups in the molecule include aliphatic polyethylene glycol-diglycidyl ester, aromatic bisphenol A-diglycidyl ester, bisphenol A- Examples thereof include diglycidyl ester initial condensates and mixtures thereof. Among the above polyfunctional compounds, examples of the compound containing three or more epoxy groups in the molecule include aliphatic trimethylolpropane-triglycidyl ether, aromatic phenol novolac epoxy resin, and cresol novolak. Type epoxy resin, bisresorcinol tetraglycidyl ether, and mixtures thereof.

Examples of the binding reaction catalyst include metal salts of carboxylic acids such as aluminum salts, sodium salts, manganese salts, alkaline earth metals, and zinc salts; manganese carbonates and the like.

  The biaxially stretched polyester layer (C) serves as a base layer for the packaging material. When the food packaging bag of the present invention is formed from the above packaging material and packaging is performed, the sealant layer (A), which is the innermost layer, must be given heat enough to be sealed. Since a sufficient sealing time cannot be secured, heat must be applied at a high temperature. For this reason, as a polyester resin used with the said biaxially-stretched polyester layer (C), a polyethylene terephthalate resin with high heat resistance is preferable.

  When a pressure bonding method using a hot plate is used as a sealing method for the food packaging bag of the present invention, the sealant layer (A) is melted by heat conduction from the biaxially stretched polyester layer (C) which is the outermost layer. . Therefore, in order to make a bag at a high speed, it is advantageous that the melting point difference between the outermost layer and the sealant layer (A) is large, and the high-speed bag making suitability is high. Therefore, when a melt composition containing a metallocene LLDPE having an extremely low melting point is used for the sealant layer (A) and a highly heat-resistant polyethylene terephthalate resin is used for the biaxially stretched polyester layer (C) that is the outermost layer Thus, heat sealing at a higher temperature is possible, and bag making at a higher speed can be realized.

Furthermore, the biaxially stretched polyester film layer is excellent in waist, transparency, and O ₂ barrier properties by being made of a biaxially stretched film.

  When printing on the food packaging bag of the present invention, the printing layer (D) is formed on the surface of the biaxially stretched polyester film layer (C) that is not in contact with the vapor deposition layer (B), or the vapor deposition layer (B ) And a biaxially stretched polyester film layer (C), or a printing layer (D) is formed between the sealant layer (A) and the vapor deposition layer (B). It is preferable. Printing is preferably performed on the biaxially stretched polyester film layer (C), which is the outermost layer, but whether to print on the inner surface side or the outer surface side of the biaxially stretched polyester film layer (C) is determined by the application. It is not limited.

  When printing is performed on the inner side of the biaxially stretched polyester film layer (C), the biaxially stretched polyester film layer (C) is transparent, so that the appearance of printing is improved. When printing is performed on the inner surface of the biaxially stretched polyester film layer (C), an adhesive is bonded between the printed surface side of the printed biaxially stretched polyester film layer (C) and the vapor deposition layer (C) surface. Paste through. Even when laminating using an adhesive, it is preferable to use non-solvent laminating in consideration of environmental compatibility.

  The printing layer (D) is not particularly limited, and for example, a commonly used ink, a non-toluene type ink, an aqueous gravure ink, or the like can be used. When considering the recycling of bags, it is preferable to use, for example, Daiekoro made by Dainippon Kogyo.

  Although it does not specifically limit as a method of producing the said packaging material, When using the said biaxially stretched polyester film layer (C) as a base material of the said vapor deposition layer (B), the said biaxially stretched polyester film layer (C) It is preferable to laminate the sealant layer (A) on the surface on the vapor deposition layer (B) side of the film having the vapor deposition layer (B) formed on one side.

  When using the said polyester resin layer (E) as a base material of the said vapor deposition layer (B), the said polyester resin layer (E) and the said sealant layer (A) are formed by coextrusion, The said polyester resin layer (E) The biaxially stretched polyester film layer (C) is preferably laminated on the vapor deposition layer (B) side of the film on which the vapor deposition layer (B) is formed. The polyester resin layer (E) and the sealant layer (A) can be formed by lamination, but are preferably co-extruded in terms of cost.

  Moreover, when providing a printing layer (D), the vapor deposition layer (B) of the film which formed the polyester resin layer (E) and the sealant layer (A) by coextrusion, and formed the vapor deposition layer (B) on the polyester resin layer side. ) Side and the printed layer (D) side of the biaxially stretched polyester film (C) having the printed layer (D) formed on one side, or the vapor-deposited layer (B) is formed on the polyester resin layer side. Then, it is preferable to form a printing layer (D) thereon and laminate a biaxially stretched polyester film (C) on the printing layer (D) side.

  The food packaging bag of the present invention can be produced by heat sealing using the packaging material so that the sealant layer (A) is inside the bag. According to the present invention, it is possible to obtain a food packaging bag that can be sealed at a low temperature, has excellent oil resistance, and is provided with easy-openability. Furthermore, when a modified PET resin obtained by modifying recovered PET in consideration of the environment is used, a highly functional food packaging bag with reduced environmental burden can be obtained. In addition, when a modified PET resin is used as the layer (E) and the vapor deposition layer (B) is disposed on this surface, there is no risk of deterioration during printing, and vapor deposition that can withstand the heat history during processing is possible. In addition, oxygen barrier properties and water vapor barrier properties can be exhibited well.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited only to these examples.

Example 1
PET flakes from recovered PET bottles were modified with ethylene glycol diglycidyl ether (bifunctional compound) and trimethylolpropane triglycidyl ether (trifunctional compound) in the same manner as in Example 98 of WO98 / 44019. A biaxially stretched polyethylene terephthalate film having a thickness of 12 μm was prepared using the resin composition, and this was used as a biaxially stretched polyester film layer (C).

The surface of the obtained biaxially stretched polyester film layer (C) was subjected to alumina vapor deposition with a thickness of 800 mm by a heat vapor deposition method using a batch type vacuum vapor deposition machine to obtain a vapor deposition layer (B). Furthermore, the printing layer (D) was formed on this vapor deposition layer (B).

Separately, 75% by weight of polyethylene terephthalate, 20% by weight of metallocene LLDPE having a density of 0.918 g / cm ³ , melting point of 60 ° C., MFR of 6 g / 10 min as a compatibilizer, Vicat softening point of 40 ° C. or less, yield point Ethylene-methyl acrylate-glycidyl methacrylate terpolymer (ethylene: methyl acrylate: glycidyl methacrylate = 67 wt%: 25 wt%: 8 wt%) having a strength of 4 MPa and an elongation at break of 1100%, and a melting point of 78 ° C. An ethylene-butyl acrylate copolymer (ethylene: butyl acrylate = 70 wt%: 30 wt%) having an MFR of 2 g / 10 min, a Vicat softening point of 45 ° C., a yield strength of 9 MPa, and an elongation at break of 850%. 5% by weight of the mixture mixed at a weight ratio of 3: 7 was melt mixed and cast A sealant layer (A) having a thickness of 40 μm was produced.

  The printing layer (D) side of the biaxially stretched polyester film layer (C) on which the obtained vapor deposition layer (B) and printing layer (D) are formed and the sealant layer (A) are laminated to obtain a packaging material. It was. This structure is shown in FIG.

  When the resulting packaging material is heat-sealed so that the sealant layer (A) is on the inside of the bag, it can be sealed from a sealing temperature of about 120 ° C., and stable at a sealing temperature of about 1000 g / 15 mm at a sealing temperature of 130 ° C. did. Furthermore, since this packaging material uses a biaxially stretched polyethylene terephthalate film as the outermost layer, it can be heated at high temperatures, can withstand high temperature sealing, and can be made at high speed. For high-speed bag-making properties, the packaging material obtained is used to perform a packaging test on an actual snack confectionery packaging machine (see “APEX packaging machine” manufactured by Ishida Co., Ltd .: USP 5347795), and a packaging speed of 150 bags / min. It was confirmed that packaging with can be done. The packaging speed was about twice that of the conventional product. When packaging food, particularly in a snack confectionery packaging machine, as shown in FIG. 3, the packaging material is formed into a cylindrical shape so that the sealant layer is on the inside, and the combined back portion is first heat sealed (back seal). ) Next, the snack is put into the cylindrical snack bag. Then, both ends of the cylindrical snack confectionery bag are heat-sealed (side seal), and the bag is completed.

(Example 2)
A biaxially stretched polyethylene terephthalate film having a thickness of 12 μm was prepared and used as a biaxially stretched polyester film layer (C), and a printed layer (D) was formed on this surface.

On the other hand, a composition obtained by mixing 75% by weight of polyethylene terephthalate, 20% by weight of metallocene LLDPE having a density of 0.918 g / cm ³ and 5% by weight of the compatibilizer used in Example 1, and the same as in Example 1 The modified PET resin composition obtained by the method was coextruded to form a film having a sealant layer (A) thickness of 5 μm and a polyester resin layer (E) thickness of 30 μm. On the polyester resin layer (E) of this film, aluminum vapor deposition was performed at a thickness of 800 mm by a heat vapor deposition method using a batch type vacuum vapor deposition machine to form a vapor deposition layer (B).

  Laminate the surface on the printed layer (D) side of the biaxially stretched polyester film layer (C) on which the printed layer (D) is formed and the surface on the vapor deposited layer (B) side of the film on which the deposited layer (B) is formed. And bonded together to obtain a packaging material. This structure is shown in FIG.

  When the resulting packaging material is heat-sealed so that the sealant layer (A) is on the inside of the bag, it can be sealed from a sealing temperature of about 120 ° C., and stable at a sealing temperature of about 1000 g / 15 mm at a sealing temperature of 130 ° C. did. Furthermore, since this packaging material uses a biaxially stretched polyethylene terephthalate film as the outermost layer, it can be heated at high temperatures, can withstand high temperature sealing, and can be made at high speed.

(Example 3)
A laminated film was prepared by laminating the following two types of resins using a casting machine so as to have a thickness of 30 μm (sealant layer 15 μm, PET resin layer 15 μm). (1) A ternary copolymer of ethylene / methyl acrylate / maleic anhydride using a metallocene LLDPE having a density of 0.918 g / cm ³ and PET flakes from a recovered PET bottle in the same manner as in Example 1 of JP-A-2001-122955. Blends of polyethylene glycol and diglycidyl ether (bifunctional compound) and polyethylene-containing PET resin composition modified with trimethylolpropane triglycidyl ether (trifunctional compound) at a ratio (weight) of 20:80 Resin (polyethylene content: 43%) (2) Modified PET resin not containing polyethylene modified with bifunctional and trifunctional compounds (according to Example 1 of the specification of WO 98/44019) Produced.)

A biaxially stretched PET film (12 μm) on which the laminated PET film surface of the obtained laminated film was subjected to aluminum vapor deposition at a thickness of 800 mm by a heat vapor deposition method using a batch type vacuum vapor deposition machine. Using a non-sol bond “XC-231” and “XA-126” manufactured by Dainichi Seika Kogyo Co., Ltd. so that the vapor deposition layer and the print layer are adjacent to each other with the adhesive layer (3.3 g / m ² ) interposed therebetween. Lamination was used to produce a packaging film. The resulting packaging film was made into a bag while filling snack snacks with the packaging machine used in Example 1, and a well-sealed bag was obtained at a seal temperature of 115 ° C.

1 Sealant layer (A)
2 Deposition layer (B)
3 Biaxially stretched polyester film layer (C)
4 Print layer (D)
5 Polyester resin layer (E)
6 Back seal 7 Side seal

The present invention relates to a method for producing a food packaging bag that requires an oxygen barrier and a water vapor barrier, such as a snack confectionery bag such as potato chips.

  Conventional snack confectionery bags generally have a packaging material composition from the inside of polypropylene resin layer / polyethylene resin layer / metal aluminum vapor deposition / biaxially stretched PET (polyethylene terephthalate) layer / polyethylene resin layer / biaxially stretched polypropylene resin. Many have a six-layer structure, or a four-layer structure of polypropylene resin layer / metal aluminum vapor deposition / polyethylene resin layer / biaxially stretched polypropylene resin layer.

  The innermost polypropylene resin (PP) layer serves as a sealant. For the innermost layer, polypropylene resin is used because heat sealing is possible at a low temperature and hot tack property immediately after sealing is required. The hot tack property is necessary because air pressure or nitrogen is sealed in the bag and the bag is inflated in order to prevent breakage of the snack that is the contents of the bag. The thickness of the innermost polypropylene resin layer is often set to about 20 to 50 μm.

  The metal aluminum vapor deposition layer plays the role which blocks the light ray from the outside, and the role which prevents permeation of oxygen and water vapor. Its thickness is about 300 to 1500 mm, and it is usually deposited on a biaxially stretched PET film or a polypropylene resin film. The biaxially stretched PET film is a material that can deposit metal aluminum most stably, and a thickness of 12 μm is often used.

  The polyethylene resin (PE) layer is a laminate of a biaxially stretched PET film and an outermost biaxially stretched polypropylene resin (OPP) film, or an innermost unstretched polypropylene resin (CPP) film and a biaxially stretched PET film. It plays the role of an adhesive that attaches and has a thickness of about 15 μm. An ethylene- (meth) acrylic acid copolymer may be used as the polyethylene resin layer, and a urethane-containing adhesive or a monomer-containing adhesive that does not contain an organic solvent may be used instead of the polyethylene resin layer. is there.

  The OPP film constituting the outermost layer directly hits a heated heat seal member (seal bar) and plays a role of transmitting the heat to the innermost polypropylene resin layer, and has a thickness of about 15 to 20 μm. The packaging material for a snack cake bag having a 4-6 layer structure as described above has a total thickness of about 40-117 μm.

  As a processing method of the packaging material having the above-mentioned structure, from the cost aspect, while laminating while extruding PE between the vapor deposition surface of the PET film having a metal vapor deposition layer formed on one side and the unstretched PP film, In many cases, a processing method is employed in which PE is extruded and laminated between a non-deposited surface and a biaxially stretched film (OPP film).

  Due to recent demands for improving production efficiency, speeding up of packaging machines is required. In order to produce food packaging bags at high speed, it is necessary to perform heat bonding with a shorter sealing time. For this purpose, in order to apply a certain amount of heat, inevitably heat sealing at a high temperature in a short time is required. Necessary. Therefore, in order to give the amount of heat that was applied to the conventional sealing time in a short time, the sealing temperature must be higher. However, in the conventional packaging material configuration, the melting point difference between the innermost layer and the outermost layer is small. There was a problem that could not be sealed at high temperature. In particular, conventionally, since an OPP film is used for the outermost layer, there has been a problem that if the temperature exceeds a certain level, the surface is thermally contracted and the commercial value is lost.

  Furthermore, when vapor deposition is performed not on a highly heat-resistant PET film but on a film made of a plastic material having low heat resistance such as polypropylene resin or polyethylene resin, vapor deposition is performed at a high temperature in a vapor deposition furnace. However, since the film is drawn out → deposited → wound while applying tension in the high temperature atmosphere, the film itself is extended by the tension at the time of winding, and there is a problem that a crack occurs in the deposited layer.

  In general, various plastics are used for food packaging bags such as snack confectionery bags, but recently, from the viewpoint of resource conservation and environmental conservation, it is necessary to recycle used plastic products collected from the factory production process and general consumer market. The need for use is recognized worldwide, and reuse of polyester is also being considered.

  Therefore, an object of the present invention is to satisfy the functions (barrier properties, high-speed productivity, etc.) required to solve the above-mentioned problems, and to enable high-speed bag making with a packaging machine, such as an oxygen barrier property and a water vapor barrier such as snacks. An object of the present invention is to provide a food packaging bag capable of satisfactorily preserving foods requiring properties. Furthermore, it is one of the objects of the present invention to enable reuse of the collected material as a packaging material forming material.

The present invention Zealand layer (A), deposition layer (B), and biaxially oriented polyester film layer (C) and is to produce a packaging material which are laminated in this order, then, using the packaging material In the method for producing a food packaging bag , the layer is formed so that the layer (A) is inside the bag.
A layer (B) is formed on a layer (E) formed from a saturated polyester resin modified with a polyfunctional epoxy compound (hereinafter sometimes referred to as a modified polyester resin). It is the manufacturing method of the bag for food packaging characterized by arrange | positioning the formed layer (E) between a layer (A) and a layer (C). The present invention is described in detail below.

  ADVANTAGE OF THE INVENTION According to this invention, the food packaging bag which can favorably preserve | save the food which requires oxygen barrier property and water vapor | steam barrier properties, such as snack confectionery which can be bag-made at high speed with a packaging machine, can be provided.

It is a schematic diagram which shows the structure of the packaging material produced in the reference example . 2 is a schematic diagram illustrating a configuration of a packaging material manufactured in Example 1. FIG. It is explanatory drawing of the fin seal of pillow packaging.

In the present invention, for food packaging bag, shea Zealand layer (A), deposited layer and (B), in the packaging material a biaxially oriented polyester film layer (C) and are laminated in this order, the layer (B) Is formed using a packaging material formed on the layer (E) formed from the modified polyester resin .

The sealant layer (A) is preferably formed from a molten composition comprising a low-melting-point polyolefin resin and a polyester resin, and is the innermost layer of the food packaging bag in the present invention.
The low melting point polyolefin resin used in the layer (A) preferably has a melting point of 120 ° C. or less in order to realize high speed productivity. Such low melting point polyolefin resin is not particularly limited, and examples thereof include polyethylene, polypropylene, ethylene-propylene copolymer, and mixtures thereof.

  The low melting point polyolefin resin is preferably a single site polyolefin resin using a single site catalyst, more preferably a metallocene polyolefin resin using a metallocene catalyst, particularly a metallocene linear low density polyethylene (metallocene LLDPE). Metallocene polyethylene or metallocene polypropylene such as

In the present invention , the sealant layer (A), which is the innermost layer of the food packaging bag, has high-speed productivity, that is, it can be stably sealed with a high-speed packaging machine, and the recent barrier-free, universal In order to satisfy functions such as design, easy peel properties are required, and when foods containing fats and oils such as potato chips and snacks are packaged, functions such as oil resistance are required.

  As a result of the inventor's earnest research to satisfy these functions, particularly excellent results were obtained by using single-site LLDPE. This single-site LLDPE is produced by an innovative polymerization technique among polyethylene production techniques. The Ziegler catalyst used in the conventional production technique is a multi-site catalyst having many kinds of active sites, and the molecular weight distribution and comonomer distribution of the produced polymer tend to be wide. In contrast, single-site LLDPE can produce a homogeneous polymer with a narrow molecular weight distribution and comonomer content distribution, and a film satisfying the required functions. Single-site LLDPE is a very clean and environmentally friendly polymer because it does not contain a halogen compound such as chlorine.

  As the metallocene LLDPE, for example, a trade name “Harmolex” manufactured by Nippon Polyolefin Co., Ltd. is commercially available, and as a film made of the metallocene LLDPE, for example, HR series manufactured by KEF Film Co., Ltd. “TUX” manufactured by Nimura Chemical Co., Ltd., “LL-X” manufactured by Nimura Chemical Co., Ltd., “Suzuron-L” manufactured by Aicero Chemical Co., Ltd., and the like are commercially available.

  The polyester resin used for the layer (A) is not particularly limited. For example, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene-2,6-naphthalate (PEN), or a copolymer thereof. An aromatic polyester such as Among them, polyethylene terephthalate (PET) resin is preferable because it is mass-produced worldwide. In addition, biodegradable aliphatic polyesters such as polycaprolactone, polyethylene-succinate, polybutylene-succinate, polybutylene-succinate-adipate, and polylactic acid are also used as a material for forming the layer (A).

  The molten composition for forming the layer (A) is preferably formed by adding a compatibilizing agent or contains a polyester-polyolefin block copolymer. In forming the layer (A), even if the low melting point polyolefin resin and the polyester resin are simply blended and melted, the mixed state is poor, phase separation occurs, and a uniformly mixed molten composition is obtained. I can't. The compatibilizer increases the compatibility between the polyester and the polyolefin, and realizes a uniform melt-mixed state. In the molten composition homogenized using the compatibilizing agent, the low-melting-point polyolefin resin and the polyester resin have a sea-island structure with small islands and are uniformly dispersed.

  The state in which the polyester and the polyolefin form a micro-dispersed sea-island structure can also be realized by containing a polyolefin-polyester block copolymer. In this case, a block copolymer may be formed by introducing a chemical bond between the low-melting-point polyolefin resin and the polyester resin constituting the layer (A), or a block copolymer may be added separately. .

  As the compatibilizing agent, any known reactive or non-reactive compatibilizing agent may be used as long as it is capable of microdispersing the polyester resin and the polyolefin resin at least in a sea-island shape while taking advantage of the characteristics of both resins. Can do. For example, ethylene- (meth) acrylic acid copolymer, metal ion cross-linked structure (ionomer) of ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester-glycidyl (meth) acrylate copolymer An ethylene- (meth) acrylic acid ester copolymer, or a block copolymer composed of a styrene-ethylene-butadiene copolymer block having a carboxyl group or a derivative thereof and a styrene polymer block is preferred.

  As a compounding ratio of each component in the molten composition forming the layer (A), the polyolefin resin is 5 to 50% by weight, the polyester resin is 50 to 95% by weight, and the compatibilizer is 2 to 20% by weight. Is preferred. If the polyolefin resin is less than 5% by weight, sufficient sealability may not be obtained, and if it exceeds 50% by weight, the adhesion to the polyester substrate layer becomes poor. Further, if the compatibilizer is less than 2% by weight, the mixed state of the polyolefin resin and the polyester resin may be insufficient, and even if added in excess of 20% by weight, the effect of further improving the mixed state is recognized. I can't.

  The polyolefin-polyester block copolymer is formed by, for example, heating a polyester resin and a carboxylic acid-modified polyolefin in the presence of a bifunctional or trifunctional epoxy compound as disclosed in JP-A-2001-122955. The block copolymer etc. which were made are mentioned. Modification of the polyester resin with the polyfunctional compound will be described later. When the polyolefin-polyester block copolymer is melted, since the polyester and the polyolefin are chemically bonded, the mixed state is very good. When a polyolefin resin is further added to the block copolymer, a micro-dispersed sea island state is obtained.

  The molten composition forming the layer (A) preferably has a heat sealing property at 120 ° C. or lower. This enables high-speed bag making in combination with the outermost layer being a biaxially stretched polyester film layer having high heat resistance.

The sealant layer (A) is preferably made of a substantially unoriented film formed without performing a stretching treatment. In general, stretching of plastic is performed by stretching in the longitudinal and transverse biaxial directions at a temperature lower by 10 to 20 ° C. than the melting point, and then heat-setting, but the stretched film is lower than the unstretched film. Each of the O ₂ barrier properties and the like is improved about three times, and these physical properties are maintained up to the heat setting temperature. However, when the temperature is higher than the heat-fixed temperature, the orientation due to stretching is disturbed and shrinkage occurs, and in heat sealing, the heat sealing part becomes wrinkled, resulting in an unsatisfactory heat sealing. Therefore, the sealant layer (A) is preferably made of a substantially unoriented unstretched resin film formed without performing a stretching treatment.

  For the sealant layer (A), a resin kneaded with additives as appropriate in order to impart hot tack property and antistatic property may be used.

  The thickness of the sealant layer (A) is preferably 2 to 20 μm in both cases of a single layer or two or more layers. If the thickness is less than 2 μm, the thickness necessary for sufficient sealing cannot be maintained due to uneven thickness at the time of molding, and the fluid may flow due to high pressure at the time of sealing, so that the sealing performance cannot be maintained. On the other hand, when the thickness exceeds 20 μm, the thickness of the entire packaging material increases, and pinholes are likely to occur at the overlapping portion between the vertical seal and the horizontal seal during sealing. More preferably, it is 3-10 micrometers.

The sealant layer (A) is composed of a molten composition in which a low-melting-point polyolefin resin and a polyester resin form a micro-dispersed sea-island structure. Therefore, the low-melting-point polyolefin resin has high sealant properties and hot tack properties, and a polyester resin. It has both high heat resistance and fragrance retention. In particular, when metallocene polyethylene or metallocene polypropylene is used as the polyolefin resin, it has low-temperature sealing properties, food safety, and oil resistance. By the sealant layer (A) and inner bag, food packaging bag according to the present invention, at the same time high-speed bag becomes possible, it can be stored without skipping flavors such as potato chips or snacks .

  Furthermore, the sealant layer (A) has a high affinity for both the polyolefin resin and the polyester resin, and even when it is laminated with a layer made of different materials, it can obtain a very good interlayer adhesive strength. it can. Usually, as the sealant layer (A), an unstretched / highly stretched film is used. However, if the adhesive strength between the sealant layer (A) and the other layers as the base material is poor, the sealant layer ( A) and the layer serving as the base material are peeled off, and the layer serving as the base material breaks immediately. However, since only the sealant layer extends following the spread of the opening, there is a problem that it is difficult to open the sealant. However, in the present invention, since the adhesive strength between the sealant layer (A) and the base layer is extremely excellent as described above, the sealant layer (A) is not separated from the other layers when the bag is opened. Since it breaks, there is an effect that opening is facilitated.

  The vapor deposition layer (B) is a barrier layer having an oxygen barrier property and a water vapor barrier property. As such a vapor deposition layer (B), the metal vapor deposition layer and ceramic vapor deposition layer which vapor-deposit metal and / or a ceramic are mentioned, for example.

As the vapor deposition layer (B), SiOx, alone deposition layer of _Al 2 _{O 3} or Al, _{or, SiOx / Al 2 O 3,} SiOx / ZnO, SiOx / CaO, SiOx / B 2 O 3, CaO / Ca A binary vapor deposition layer made of (OH) ₂ is used. As the SiOx, for _{example, SiO 2, SiO 1.8, SiO} 1.6 , and the like. Especially, it is preferable to form from metal aluminum, aluminum oxide, or silicon oxide.

  In the case where a metal detector or the like is used in order to find out contamination of foreign matters in advance, a ceramic vapor deposition layer is preferable as the vapor deposition layer (B). By performing ceramic vapor deposition, it is possible to inspect even a foreign object detector that could not be performed by conventional metal vapor deposition using a metal detector.

  The thickness of the vapor deposition layer (B) is preferably 300 to 1500 mm. If the thickness is less than 300 mm, uniform vapor deposition is difficult. If the thickness exceeds 1500 mm, the thickness of the entire packaging material increases, and pinholes are likely to occur at the overlap between the vertical seal and the horizontal seal during sealing.

The said vapor deposition layer (B) is obtained by vapor-depositing a metal and / or a ceramic on a base material. For this reason, the film constituting the substrate is preferably one having heat resistance sufficient to withstand the heat history during vapor deposition, and in the present invention, it is formed from a saturated polyester resin modified with a polyfunctional epoxy compound. The layer (E) thus formed is used as a base material for the vapor deposition layer (B). In this case, in the obtained food packaging bag, a layer (E) made of the modified polyester resin is formed between the layer (A) and the layer (B).

Although it does not specifically limit as saturated polyester resin used by the said layer (E), It is preferable to use a recycled resin from consideration to an environment. The recycled resin is not particularly limited. For example, it is preferable to use a polyester resin with improved molding processability with an increased molecular weight and molecular weight distribution using a polyester resin having a relatively low molecular weight such as a recovered polyester resin as a raw material. As such a resin, a modified polyester resin (X) obtained by modifying a recycled resin with a polyfunctional epoxy compound can be used. Such a modified polyester resin can also be used as a resin constituting the layer (C).

  As said modified polyester resin (X), the resin obtained by mix | blending a specific epoxy compound and a coupling reaction catalyst as a multifunctional compound with saturated polyester, and heat-melting is mentioned, for example. More specifically, (a) 100 parts by weight of a linear saturated polyester, (b) 0-100% by weight of a compound containing 2 epoxy groups in the molecule as a polyfunctional compound, and 3 or more epoxy groups A compound composed of 0.3 to 10 parts by weight of a mixture containing 100 to 0% by weight of a compound containing (a) and (c) 0.01 to 5 parts by weight of a binding reaction catalyst, and a temperature not lower than the melting point of the linear saturated polyester. A resin obtained by heating at a temperature can be used (see International Publication No. WO98 / 44019).

  The linear saturated polyester is preferably a polyethylene terephthalate aromatic polyester having an intrinsic viscosity of 0.50 to 0.90 dl / g, and is a recycled product of the recovered polyethylene terephthalate aromatic polyester molded product. Is preferred.

  Among the polyfunctional compounds, examples of the compound containing two epoxy groups in the molecule include aliphatic polyethylene glycol-diglycidyl ester, aromatic bisphenol A-diglycidyl ester, bisphenol A- Examples thereof include diglycidyl ester initial condensates and mixtures thereof. Among the above polyfunctional compounds, examples of the compound containing three or more epoxy groups in the molecule include aliphatic trimethylolpropane-triglycidyl ether, aromatic phenol novolac epoxy resin, and cresol novolak. Type epoxy resin, bisresorcinol tetraglycidyl ether, and mixtures thereof.

Examples of the binding reaction catalyst include metal salts of carboxylic acids such as aluminum salts, sodium salts, manganese salts, alkaline earth metals, and zinc salts; manganese carbonates and the like.

The biaxially stretched polyester layer (C) serves as a base layer for the packaging material. When performing the formed packaging food packaging bag according to the present invention from the packaging material, must be given a heat quantity as possible is sealed to the sealant layer (A) is the innermost layer, it is packaged in a high speed packaging machine In some cases, sufficient sealing time cannot be secured, and heat must be applied at a high temperature. For this reason, as a polyester resin used with the said biaxially-stretched polyester layer (C), a polyethylene terephthalate resin with high heat resistance is preferable.

In the present invention , when a pressure bonding method using a hot plate is used as a sealing method for food packaging bags, the sealant layer (A) is melted by heat conduction from the biaxially stretched polyester layer (C) which is the outermost layer. Become. Therefore, in order to make a bag at a high speed, it is advantageous that the melting point difference between the outermost layer and the sealant layer (A) is large, and the high-speed bag making suitability is high.
Therefore, when a melt composition containing a metallocene LLDPE having an extremely low melting point is used for the sealant layer (A) and a highly heat-resistant polyethylene terephthalate resin is used for the biaxially stretched polyester layer (C) that is the outermost layer Thus, heat sealing at a higher temperature is possible, and bag making at a higher speed can be realized.

Furthermore, the biaxially stretched polyester film layer is excellent in waist, transparency, and O ₂ barrier properties by being made of a biaxially stretched film.

In the present invention , when printing is performed on a food packaging bag, a printing layer (D) is formed on the surface of the biaxially stretched polyester film layer (C) that is not in contact with the vapor deposition layer (B), or the vapor deposition layer ( A printing layer (D) is formed between B) and the biaxially stretched polyester film layer (C), or a printing layer (D) is formed between the sealant layer (A) and the vapor deposition layer (B). It is preferable to do. Printing is preferably performed on the biaxially stretched polyester film layer (C), which is the outermost layer, but whether to print on the inner surface side or the outer surface side of the biaxially stretched polyester film layer (C) is determined by the application. It is not limited.

  When printing is performed on the inner side of the biaxially stretched polyester film layer (C), the biaxially stretched polyester film layer (C) is transparent, so that the appearance of printing is improved. When printing is performed on the inner surface of the biaxially stretched polyester film layer (C), an adhesive is bonded between the printed surface side of the printed biaxially stretched polyester film layer (C) and the vapor deposition layer (C) surface. Paste through. Even when laminating using an adhesive, it is preferable to use non-solvent laminating in consideration of environmental compatibility.

  The printing layer (D) is not particularly limited, and for example, a commonly used ink, a non-toluene type ink, an aqueous gravure ink, or the like can be used. When considering the recycling of bags, it is preferable to use, for example, Daiekoro made by Dainippon Kogyo.

In the case of using the modified polyester resin layer (E) as the base material of the deposited layer (B), the modified polyester resin layer (E) and the sealant layer (A) is formed by co-extrusion, the reforming The biaxially stretched polyester film layer (C) is preferably laminated on the vapor deposition layer (B) side of the film having the vapor deposition layer (B) formed on the polyester resin layer (E) side. The modified polyester resin layer (E) and the sealant layer (A) can be molded by lamination, but are preferably co-extruded in terms of cost.

Moreover, when providing a printing layer (D), the vapor deposition layer of the film which formed the modified polyester resin layer (E) and the sealant layer (A) by coextrusion, and formed the vapor deposition layer (B) on the polyester resin layer side. Laminate the (B) side and the printing layer (D) side of the biaxially stretched polyester film (C) having the printing layer (D) formed on one side, or the vapor deposition layer (B) on the polyester resin layer side. Then, it is preferable to form a printed layer (D) thereon, and laminate a biaxially stretched polyester film (C) on the printed layer (D) side.

The food packaging bag according to the present invention can be produced by heat-sealing using the packaging material so that the sealant layer (A) is inside the bag. According to the present invention, it is possible to obtain a food packaging bag that can be sealed at a low temperature, has excellent oil resistance, and is provided with easy-openability. Furthermore, when a modified PET resin obtained by modifying recovered PET in consideration of the environment is used, a highly functional food packaging bag with reduced environmental burden can be obtained. Further, using the modified PET resin as a layer (E), when placing the deposited layer (B) on the surface, no fear of deterioration in the printing process, can withstand Eur deposited to heat history during processing Thus, the oxygen barrier property and the water vapor barrier property can be expressed well.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited only to these examples.

( Reference example )
PET flakes from recovered PET bottles were modified with ethylene glycol diglycidyl ether (bifunctional compound) and trimethylolpropane triglycidyl ether (trifunctional compound) in the same manner as in Example 98 of WO98 / 44019. A biaxially stretched polyethylene terephthalate film having a thickness of 12 μm was prepared using the resin composition, and this was used as a biaxially stretched polyester film layer (C).

  The surface of the obtained biaxially stretched polyester film layer (C) was subjected to alumina vapor deposition with a thickness of 800 mm by a heat vapor deposition method using a batch type vacuum vapor deposition machine to obtain a vapor deposition layer (B). Furthermore, the printing layer (D) was formed on this vapor deposition layer (B).

Separately, 75% by weight of polyethylene terephthalate, 20% by weight of metallocene LLDPE having a density of 0.918 g / cm ³ , melting point of 60 ° C., MFR of 6 g / 10 min as a compatibilizer, Vicat softening point of 40 ° C. or less, yield point Ethylene-methyl acrylate-glycidyl methacrylate terpolymer (ethylene: methyl acrylate: glycidyl methacrylate = 67 wt%: 25 wt%: 8 wt%) having a strength of 4 MPa and an elongation at break of 1100%, and a melting point of 78 ° C. An ethylene-butyl acrylate copolymer (ethylene: butyl acrylate = 70 wt%: 30 wt%) having an MFR of 2 g / 10 min, a Vicat softening point of 45 ° C., a yield strength of 9 MPa, and an elongation at break of 850%. 5% by weight of the mixture mixed at a weight ratio of 3: 7 was melt mixed and cast A sealant layer (A) having a thickness of 40 μm was produced.

  The printing layer (D) side of the biaxially stretched polyester film layer (C) on which the obtained vapor deposition layer (B) and printing layer (D) are formed and the sealant layer (A) are laminated to obtain a packaging material. It was. This structure is shown in FIG.

  When the resulting packaging material is heat-sealed so that the sealant layer (A) is on the inside of the bag, it can be sealed from a sealing temperature of about 120 ° C., and stable at a sealing temperature of about 1000 g / 15 mm at a sealing temperature of 130 ° C. did. Furthermore, since this packaging material uses a biaxially stretched polyethylene terephthalate film as the outermost layer, it can be heated at high temperatures, can withstand high temperature sealing, and can be made at high speed. For high-speed bag-making properties, the packaging material obtained is used to perform a packaging test on an actual snack confectionery packaging machine (see “APEX packaging machine” manufactured by Ishida Co., Ltd .: USP 5347795), and a packaging speed of 150 bags / min. It was confirmed that packaging with can be done. The packaging speed was about twice that of the conventional product. When packaging food, particularly in a snack confectionery packaging machine, as shown in FIG. 3, the packaging material is formed into a cylindrical shape so that the sealant layer is on the inside, and the combined back portion is first heat sealed (back seal). ) Next, the snack is put into the cylindrical snack bag. Then, both ends of the cylindrical snack confectionery bag are heat-sealed (side seal), and the bag is completed.

(Example 1 )
A biaxially stretched polyethylene terephthalate film having a thickness of 12 μm was prepared and used as a biaxially stretched polyester film layer (C), and a printed layer (D) was formed on this surface.

On the other hand, a 75 wt% polyethylene terephthalate, a metallocene LLDPE20 wt% density of 0.918 g / cm ^3, a composition obtained by mixing a compatibilizing agent 5 wt% was used in Reference Example, in the same manner as in Reference Example The obtained modified PET resin composition was coextruded to form a film, and a film having a sealant layer (A) thickness of 5 μm and a modified polyester resin layer (E) thickness of 30 μm was obtained. On the modified polyester resin layer (E) of this film, aluminum vapor deposition was applied to a thickness of 800 mm by a heat vapor deposition method using a batch type vacuum vapor deposition machine to form a vapor deposition layer (B).

  Laminate the surface on the printed layer (D) side of the biaxially stretched polyester film layer (C) on which the printed layer (D) is formed and the surface on the vapor deposited layer (B) side of the film on which the deposited layer (B) is formed. And bonded together to obtain a packaging material. This structure is shown in FIG.

  When the resulting packaging material is heat-sealed so that the sealant layer (A) is on the inside of the bag, it can be sealed from a sealing temperature of about 120 ° C., and stable at a sealing temperature of about 1000 g / 15 mm at a sealing temperature of 130 ° C. did. Furthermore, since this packaging material uses a biaxially stretched polyethylene terephthalate film as the outermost layer, it can be heated at high temperatures, can withstand high temperature sealing, and can be made at high speed.

(Example 2)
A laminated film was prepared by laminating the following two types of resins using a casting machine so as to have a thickness of 30 μm (sealant layer 15 μm, PET resin layer 15 μm). (1) A ternary copolymer of ethylene / methyl acrylate / maleic anhydride using a metallocene LLDPE having a density of 0.918 g / cm ³ and PET flakes from a recovered PET bottle in the same manner as in Example 1 of JP-A-2001-122955. Blends of polyethylene glycol and diglycidyl ether (bifunctional compound) and polyethylene-containing PET resin composition modified with trimethylolpropane triglycidyl ether (trifunctional compound) at a ratio (weight) of 20:80 Resin (polyethylene content: 43%) (2) Modified PET resin not containing polyethylene modified with bifunctional and trifunctional compounds (according to Example 1 of the specification of WO 98/44019) Produced.)

A biaxially stretched PET film (12 μm) on which the laminated PET film surface of the obtained laminated film was subjected to aluminum vapor deposition at a thickness of 800 mm by a heat vapor deposition method using a batch type vacuum vapor deposition machine. Using a non-sol bond “XC-231” and “XA-126” manufactured by Dainichi Seika Kogyo Co., Ltd. so that the vapor deposition layer and the print layer are adjacent to each other with the adhesive layer (3.3 g / m ² ) interposed therebetween. Lamination was used to produce a packaging film. A bag was produced from the resulting packaging film while filling snack snacks with the packaging machine used in the reference example , and a bag that was well sealed at a seal temperature of 115 ° C. was obtained.

1 Sealant layer (A)
2 Deposition layer (B)
3 Biaxially stretched polyester film layer (C)
4 Print layer (D)
5 Modified polyester resin layer (E)
6 Back seal 7 Side seal

The present invention produces a packaging material in which a sealant layer (A), a vapor deposition layer (B), and a biaxially stretched polyester film layer (C) are laminated in this order, and then using the packaging material, In the method for producing a food packaging bag, the layer (A) is formed so that the bag is located inside the bag.
A layer (B) is formed on an unstretched film layer (E) formed from a saturated polyester resin modified with a polyfunctional epoxy compound (hereinafter sometimes referred to as a modified polyester resin). A method for producing a food packaging bag, wherein the layer (E) on which B) is formed is disposed between the layer (A) and the layer (C). The present invention is described in detail below.

Claims (18)

  A packaging material in which a sealant layer (A), a vapor deposition layer (B), and a biaxially stretched polyester film layer (C) formed from a molten composition comprising a low-melting polyolefin resin and a polyester resin are laminated in this order. A food packaging bag, wherein the layer (A) is formed so as to be inside the bag.   The food packaging bag according to claim 1, wherein the polyolefin resin of the layer (A) has a melting point of 120 ° C or lower.   The food packaging bag according to claim 1 or 2, wherein the polyolefin resin of the layer (A) is metallocene polyethylene or metallocene polypropylene.   The food packaging bag according to any one of claims 1 to 3, wherein the polyester resin of the layer (A) is polyethylene terephthalate.   The food packaging bag according to any one of claims 1 to 4, wherein the molten composition of the layer (A) comprises a polyester-polyolefin block copolymer.   The food packaging bag according to any one of claims 1 to 4, wherein the layer (A) is formed by adding a compatibilizing agent to a low melting point polyolefin resin and a polyester resin and melt-mixing them.   Compatibilizers are ethylene- (meth) acrylic acid copolymer, metal ion cross-linked structure of ethylene- (meth) acrylic acid copolymer (ionomer), ethylene- (meth) acrylic acid ester-glycidyl (meth) acrylate A block copolymer comprising a copolymer, an ethylene- (meth) acrylic ester copolymer, or a styrene-ethylene-butadiene copolymer block having a carboxyl group or a derivative thereof and a styrene polymer block. Item 7. A food packaging bag according to Item 6.   The bag for food packaging according to claim 6 or 7, wherein the molten composition of the layer (A) comprises 5 to 50% by weight of a polyolefin resin, 50 to 95% by weight of a polyester resin, and 2 to 20% by weight of a compatibilizer.   The food packaging bag according to any one of claims 5 to 8, wherein the molten composition of the layer (A) has a sea-island structure.   The food packaging bag according to any one of claims 1 to 9, wherein the molten composition of the layer (A) has a heat sealing property at 120 ° C or lower.   The food packaging bag according to any one of claims 1 to 10, wherein the vapor deposition layer of the layer (B) is formed of metal aluminum, aluminum oxide, or silicon oxide.   The bag for food packaging according to any one of claims 1 to 11, wherein the biaxially stretched polyester film of the layer (C) is formed from polyethylene terephthalate.   The food packaging bag according to any one of claims 1 to 12, wherein the layer (A) is laminated on the layer (B) side surface of the layer (C) having the layer (B) formed on one side.   The printed layer (D) is formed between the layer (A) and the layer (B), between the layer (B) and the layer (C), or on the layer (C). The food packaging bag according to any one of the above.   The food packaging bag according to any one of claims 1 to 14, wherein a polyester resin layer (E) is formed between the layer (A) and the layer (B).   16. The food product according to claim 15, wherein the layer (C) is laminated on the layer (B) side of the layer (E) in which the layer (B) is formed on one side and the layer (A) is formed on the opposite side. Packaging bag.   The layer (B) is formed on one side, and then the layer (D) is formed thereon, and the layer (E) is formed on the opposite side. The food packaging bag according to claim 15, wherein the bag is laminated.   The food packaging bag according to any one of claims 1 to 17, wherein the polyester resin of the layer (A), the layer (C) or the layer (E) is a recycled resin.

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