JP2020111004A - Lid material for deep draw packaging including biaxially stretched polybutylene terephthalate-based film - Google Patents

Abstract

To provide a lid material for deep draw packaging that has excellent glossiness and printing pitch dimension accuracy, is less likely to cause curling of a heat-sealed flange part after boiling treatment or retort treatment and is less likely to cause whitening of the heat-sealed part.SOLUTION: The lid material for deep draw packaging is composed of (a) a laminate including an outermost layer 21 formed of a biaxially stretched polybutylene terephthalate film comprising either of a polybutylene terephthalate resin and a polyester-based resin composition having a polyethylene terephthalate resin blended in the range of 30 mass% or less based on the polybutylene terephthalate resin, an oxygen barrier layer 22 and a sealant layer 23 or (b) a laminate including the outermost layer 21 and the sealant layer 23.SELECTED DRAWING: Figure 2

Description

The present invention relates to a deep-drawing packaging lid material, more specifically, a deep-drawing packaging suitable for packaging foods such as processed meat products such as sliced ham and sausage, dairy products such as cheese, and the like. The present invention relates to a lid material.

Usually, foods such as sliced ham are distributed and sold in a deep-drawn package. For example, as shown in FIG. 1, the deep-drawing package 10 includes a flange portion 13 of a deep-drawing packaging bottom material 12 having a recessed portion for accommodating a food product 14 such as sliced ham in a central portion, and a deep-drawing packaging lid material. It is obtained by heat sealing with 11.

Conventionally, as a deep-drawing packaging lid material used in the food field, for example, in the case of retort applications, a layer made of a homo unstretched polypropylene (hereinafter, also referred to as “CPP”) film, a gas barrier layer, and a sealing layer. A deep-drawing packaging lid material in which layers made of CPP film are arranged in this order is used, and in the case of boiling use, a layer made of CPP film, a gas barrier layer, and a linear low-density polyethylene resin layer as a sealing layer. Deep-drawing packaging lid materials arranged in this order are used.
Further, the purpose is to hermetically seal the deep-drawing packaging lid material and the deep-drawing packaging bottom material to give rigidity to the flange portion, and to heat seal the deep-drawing packaging lid material and the deep-drawing packaging bottom material. After that, for the purpose of preventing the heat-sealed flange portion from curling, a biaxially stretched polyethylene terephthalate (hereinafter also referred to as "OPET") film or a CPP film is used as the outermost layer forming the lid material for deep-drawing packaging. It is used.

However, when the OPET film is used as the outermost layer of the deep-drawing packaging lid material, there is a problem that the pinhole resistance of the deep-drawing packaging lid material is not sufficient. On the other hand, when a CPP film is used as the outermost layer of the deep-drawing packaging lid, the printing pitch dimension accuracy of the deep-drawing packaging lid is not sufficient, and the CPP film is an unstretched film. There is a problem that the luster of the material is poor and the appearance of the contents is impaired, and the heat-sealed part between the deep-drawing packaging lid material and the deep-drawing packaging bottom material may be whitened. There was a problem of difficulty.

In addition, if a biaxially stretched nylon film or unstretched nylon film is used as the outermost layer of the deep-drawing packaging cover material, the film itself has hygroscopicity, so the flange portion heat-sealed after boil treatment or retort treatment is curled. However, there was a problem that the product value declined.
Furthermore, in recent years, for the purpose of increasing the commercial value, it has been required to make the lid material for deep-drawing packaging transparent and to prevent the heat-sealed portion from being whitened.

On the other hand, in Patent Document 1, a polybutylene terephthalate resin layer, a polyethylene terephthalate resin layer, a gas barrier layer, and an easy peel layer are provided in this order, and the ratio of the polyethylene terephthalate resin layer thickness to the total film thickness is 30% or more 75 By using a co-extruded unstretched film for a deep-drawing package of less than 10%, a deep-drawing package has been proposed in which the curl of the heat-sealed portion is small and the heat-sealed portion does not whiten.

JP, 2018-12201, A

As described above, the deep-drawing packaging lid material using the CPP film as the outermost layer can prevent the flange portion from curling, but since the CPP film is an unstretched film, the printing pitch dimensional accuracy and glossiness are improved. Was insufficient, and whitening of the heat-sealed portion could not be sufficiently suppressed. On the other hand, the deep-drawing packaging lid material using the OPET film as the outermost layer has sufficient printing pitch dimensional accuracy and glossiness, but has a problem of insufficient pinhole resistance.

Further, since the coextrusion unstretched film for deep-drawing package proposed in Patent Document 1 is a coextrusion unstretched film, there is a problem that the printing pitch dimension accuracy is not sufficient.

Therefore, an object of the present invention is a deep-drawing package that has excellent glossiness and print pitch dimensional accuracy, and that the heat-sealed flange portion is less likely to curl and the heat-sealed portion is less likely to be whitened even after boil treatment or retort treatment. The purpose is to provide a lid material for use.

The present inventor, as a result of earnest research to solve the above problems, the outermost layer, an oxygen barrier layer, a laminate containing a sealant layer, or a deep-drawing package consisting of a laminate containing an outermost layer and a sealant layer. By using a biaxially stretched polybutylene terephthalate (hereinafter, also referred to as "OPBT") type film as the outermost layer in a lid material for use, it has excellent glossiness and printing pitch dimensional accuracy, and after boil treatment or retort. The present invention has been completed by finding that a lid material for deep-drawing packaging in which the heat-sealed flange portion is hard to curl even after the treatment and the heat-sealed portion is hard to be whitened can be obtained.

That is, the present invention provides the following deep-drawing packaging lid material and deep-drawing packaging body.
[1] A biaxially stretched polybutylene terephthalate-based film made of either a polybutylene terephthalate resin or a polyester-based resin composition obtained by blending a polyethylene terephthalate resin in an amount of 30% by mass or less with respect to a polybutylene terephthalate resin. A lid material for deep-drawing packaging, comprising a laminate including an outer layer, an oxygen barrier layer, and a sealant layer, or a laminate including the outermost layer and a sealant layer.
[2] The biaxially stretched polybutylene terephthalate-based film is a film having a heat shrinkage rate of 0.1% to 5% at 150° C. in the longitudinal direction (MD) and the width direction (TD), [1 ] The lid material for deep-drawing packaging according to [1].
[3] The biaxially stretched polybutylene terephthalate film has a ratio (MD/TD) of a 150° C. heat shrinkage ratio in the longitudinal direction (MD) to a 150° C. heat shrinkage ratio in the width direction (TD), or the biaxially stretched film. The ratio (TD/MD) of the 150° C. heat shrinkage ratio in the width direction (TD) and the 150° C. heat shrinkage ratio in the longitudinal direction (MD) of the polybutylene terephthalate film is 1.0 to 30.0. The lid material for deep-drawing packaging according to [1] or [2], which is characterized by:
[4] The biaxially stretched polybutylene terephthalate film is a film having a tensile breaking strength of 170 MPa or more in all four directions (0° (MD), 45°, 90° (TD), 135°). The lid material for deep-drawing packaging according to any one of [1] to [3].

[5] A deep-drawing packaging body comprising: a deep-drawing packaging lid material; and a deep-drawing packaging bottom material having a recess for accommodating contents and a flange portion that is stuck to the deep-drawing packaging lid material. hand,
A deep-drawing packaging body, wherein the deep-drawing packaging lid material is the deep-drawing packaging lid material according to any one of [1] to [4].

ADVANTAGE OF THE INVENTION According to this invention, the deep-drawing packaging lid which has the outstanding glossiness and the printing pitch dimensional accuracy, and is hard to curl the heat-sealed flange part after a boil process or a retort process, and is hard to whiten a heat-sealed part. Material can be provided.

FIG. 1 is a schematic view showing an example of a deep-drawing package. FIG. 2 is a schematic cross-sectional view of a deep-drawing packaging lid material according to an embodiment of the present invention [(a) a deep-drawing packaging lid material composed of a laminate including a base material layer, an oxygen barrier layer, and a sealant layer. Schematic sectional view. (B) A schematic cross-sectional view of a deep-drawing packaging lid member made of a laminate including a base material layer and a sealant layer. ]. FIG. 3 is a schematic view of a tubular simultaneous biaxial stretching device.

Hereinafter, modes for carrying out the present invention will be specifically described.
As shown in FIG. 2( a ), the deep-drawing packaging lid material of the present invention is a laminated body including an outermost layer 21 made of an OPBT-based film, an oxygen barrier layer 22, and a sealant layer 23, or FIG. As shown in (b), it is composed of a laminate including an outermost layer 21 made of an OPBT film and a sealant layer 23.
Further, in the deep-drawing packaging lid material of the present invention, a printing layer may be provided between the outermost layer 21 and the oxygen barrier layer 22 or between the outermost layer 21 and the sealant layer 23, and the outermost layer 21, One or more intermediate layers such as an adhesive resin layer may be provided between the oxygen barrier layer 22 and the sealant layer 23 or between the outermost layer 21 and the sealant layer 23.
In the present specification, "unstretched" has the same meaning as "non-stretched".

[Structure of lid material for deep-drawing packaging]
<Outermost layer>
The outermost layer of the lid material for deep-drawing packaging of the present invention is made of either a polybutylene terephthalate resin or a polyester resin composition in which a polyethylene terephthalate resin is blended in the range of 30% by mass or less with respect to the polybutylene terephthalate resin. It is composed of a biaxially stretched polybutylene terephthalate film.

As the outermost layer, an oxygen barrier OPBT film such as an alumina vapor-deposited OPBT film (a film obtained by vapor-depositing an OPBT film on an alumina film) or a silica vapor-deposited OPBT film (a film obtained by vapor-depositing a silica film on an OPBT film) is used. It may be used, in which case the oxygen barrier layer may or may not be separately provided.

(Raw material for OPBT film)
The polybutylene terephthalate (hereinafter, also referred to as “PBT”) resin used for the OPBT film is not particularly limited as long as it is a polyester having butylene terephthalate as a main repeating unit, but specifically, a glycol component Of 1,4-butanediol or an ester-forming derivative thereof as a main component and terephthalic acid as a dibasic acid component or an ester-forming derivative thereof as a main component, and a homo- or copolymer-type compound obtained by condensing them It is polyester. In order to impart optimum mechanical strength characteristics, polybutylene terephthalate resins having a melting point of 200 to 250° C. and an IV value of 1.10 to 1.35 dl/g are preferable, and further have a melting point of 215 to 225. Those having a temperature of IV and an IV value of 1.15 to 1.30 dl/g are particularly preferable.

The PBT resin used in the present invention includes a polyethylene terephthalate (hereinafter, also referred to as “PET”) resin in an amount of 30% by mass or less, preferably 5 to 30% by mass, based on the PBT resin. Preferably, it can be appropriately blended in the range of 10 to 30% by mass, and by blending the PET resin, crystallization of the PBT resin can be appropriately suppressed, and the stretching processability is remarkably improved. The PET resin to be blended is not particularly limited as long as it is a polyester having ethylene terephthalate as a main repeating unit. Specifically, ethylene glycol as a glycol component and terephthalic acid as a dibasic acid component as main components are used. The homotype described above is particularly preferable. In order to impart optimum mechanical strength properties, among the PET resins, those having a melting point of 240 to 265° C. and an IV value of 0.55 to 0.90 dl/g are preferable, and further a melting point of 245 to 260° C. Those having an IV value in the range of 0.60 to 0.80 dl/g are particularly preferable. If the PET resin is blended in an amount of more than 30% by mass, the rigidity of the stretched film or the unstretched raw fabric becomes too high, and as a result, the compressive strength, the impact strength and the puncture strength are reduced, and stretch defects due to the raw fabric crack occur. It is not preferable because it may occur.

Further, the PBT resin used in the present invention may include a lubricant, an anti-blocking agent, an inorganic extender, an antioxidant, an ultraviolet absorber, an antistatic agent, a flame retardant, a plasticizer, a colorant, and a crystallization inhibitor, if necessary. Additives such as agents and crystallization accelerators can be added.
The PBT resin pellets and the PET resin pellets used in the present invention have a water content of preferably 0.05% by mass or less, more preferably 0.01% by mass or less before heating and melting in order to avoid a decrease in viscosity due to hydrolysis during heating and melting. It is preferable to use it after sufficiently pre-drying it so that the amount becomes not more than %.

(Method for manufacturing PBT-based unstretched original fabric)
In order to stably produce an OPBT-based film, it is necessary to suppress the crystallization of the unstretched unstretched raw fabric as much as possible, and when the extruded PBT-based melt is cooled to form a film, crystals of the PBT-based resin The material temperature is cooled at a certain rate or higher, that is, the original fabric cooling rate is an important factor. The original fabric cooling rate is 200° C./sec or more, preferably 250° C./sec or more, particularly preferably 350° C./sec or more, and the unstretched original fabric formed at a high cooling rate is extremely low. Since the crystalline state is maintained, the stability of bubbles during stretching is dramatically improved. Further, since the film can be formed at a high speed, the productivity is improved. If the cooling rate is less than 200° C./sec, not only the crystallinity of the obtained unstretched raw fabric may be increased and the stretchability may be lowered, but also in an extreme case, the stretched bubbles may burst and the stretching may not continue. There are cases.

The raw film formation method is not particularly limited as long as it is a method satisfying the above-described raw fabric cooling rate, but the inner and outer direct water cooling type is most suitable in terms of rapid cooling film formation. The outline of the raw film forming method using the direct water cooling method inside and outside will be described below.
First, the PBT-based resin is melt-kneaded by an extruder set to a temperature of 210 to 280° C., and in the case of T-die film formation, the sheet-shaped molten resin is immersed in a water tank for direct water cooling both inside and outside. On the other hand, in the case of the annular film formation, the molten tubular thin film is formed by extruding downward from an annular die attached downward to the extruder.

Then, the cooling water introduced into the cooling mandrel connected to the annular die and introduced from each nozzle of the cooling mandrel directly contacts the inside of the molten tubular thin film to cool the molten tubular thin film. At the same time, cooling water is made to flow from the external cooling tank used in combination with the cooling mandrel, and the cooling water also comes into direct contact with the outside of the molten tubular thin film to cool the molten tubular thin film. The temperature of the internal water and the external water is preferably 30° C. or lower, and particularly preferably 20° C. or lower from the viewpoint of rapid film formation. If the temperature is higher than 30°C, whitening of the raw fabric or poor appearance of the raw fabric due to boiling of cooling water may occur, and stretching may become gradually difficult.

(Method for manufacturing OPBT film)
The PBT-based unstretched raw fabric needs to be conveyed to the stretching zone while being kept at an ambient temperature of 25° C. or lower, preferably 20° C. or lower, and under the temperature control, the unstretched raw fabric immediately after film formation is irrelevant. Anti-crystallinity can be maintained. It can be said that the crystallization control up to the stretching start point is an important point for stable biaxial stretching of the PBT-based resin together with the film-forming technique for the unstretched raw fabric.

The biaxial stretching method is not particularly limited, and is appropriately selected from, for example, a tubular method or a tenter method in which the biaxial stretching is performed simultaneously in the vertical and horizontal directions or sequentially. The simultaneous biaxial stretching method by the tubular method is particularly preferable from the viewpoint of the balance of physical properties in the circumferential direction of the obtained OPBT film. FIG. 3 is a schematic view of a tubular simultaneous biaxial stretching device. The unstretched raw fabric 31 guided to the stretching zone is inserted between a pair of nip rolls 32, then heated by a heater 33 while pressurizing air therein, and is blown with air from a cooling ring 34 at the end of stretching. Thereby, the MD and TD simultaneous biaxially stretched film 37 by the tubular method can be obtained.

The stretching ratio is preferably in the range of 2.7 to 4.5 times in each of MD and TD, in consideration of stretching stability, strength physical properties, transparency, and thickness uniformity of the obtained OPBT-based film. If the draw ratio is less than 2.7 times, the tensile strength and impact strength of the obtained OPBT film may be insufficient, which is not preferable. Further, if the stretching ratio is more than 4.5 times, excessive strain of the molecular chain is likely to occur due to stretching, so that breakage or puncture frequently occurs during stretching processing, and stable production may not be possible.
The stretching temperature is preferably in the range of 40 to 80°C, particularly preferably 45 to 65°C. Since the unstretched raw fabric produced at the high cooling rate has low crystallinity, it can be stably stretched at a stretching temperature in a relatively low temperature range. In the high temperature stretching of more than 80° C., the shaking of the stretching bubble becomes severe, and large stretching unevenness may occur, so that a film having good thickness accuracy may not be obtained. On the other hand, if the stretching temperature is lower than 40° C., excessive stretch-oriented crystallization due to low-temperature stretching is likely to occur, which may lead to whitening of the film, and in some cases, stretching bubbles may burst to make it difficult to continue stretching. By carrying out the biaxial stretching process as described above, it is possible to obtain an OPBT-based film in which the strength and physical properties are remarkably improved and the anisotropy is small.

The obtained OPBT film is placed in a heat roll system, a tenter system, or a heat treatment facility in which these are combined for an arbitrary time, and heat-treated at, for example, 180 to 240° C., particularly preferably 190 to 210° C. An OPBT film having excellent dimensional stability can be obtained. If the heat treatment temperature is higher than 240° C., the bowing phenomenon may become too large and the anisotropy in the width direction may increase, or the crystallinity may become too high and the strength physical properties may deteriorate. is there. On the other hand, when the heat treatment temperature is lower than 180° C., the thermal dimensional stability of the film may be significantly reduced, so that the film tends to shrink during lamination or printing, which may cause a problem in practical use.

In the OPBT film used in the present invention, the 150° C. heat shrinkage ratio in the longitudinal direction (MD) and the width direction (TD) is preferably 0.1 to 5.0%, more preferably 0.1 to 4%. 0.0%, and more preferably 0.1 to 3.0%. If the heat shrinkage ratio at 150°C is greater than 5.0%, the deep-drawing packaging lid material may be greatly deformed by the heat during boil processing or retort processing of the deep-drawing packaging. There is a possibility that the flange portion (heat-sealed flange portion), which is the bonding portion between the packaging lid material and the deep-drawing bottom material, may be curled, and the appearance of the deep-drawing package may be impaired. If the heat shrinkage ratio at 150° C. is less than 0.1%, the MD/TD ratio becomes too large, and the heat-sealed flange portion is likely to curl, which is not preferable.

Further, in the OPBT film used in the present invention, the ratio (MD/TD) of the 150° C. heat shrinkage ratio in the longitudinal direction (MD) to the 150° C. heat shrinkage ratio in the width direction (TD), or the width direction (TD). The ratio (TD/MD) of the 150° C. heat shrinkage ratio to the 150° C. heat shrinkage ratio in the longitudinal direction (MD) is preferably 1.0 to 30.0, and more preferably 1.0 to 30.0.
It is 25.0. If the 150°C heat shrinkage ratio (MD/TD or TD/MD) is greater than 30.0, the deep-draw packaging lid material can be significantly deformed by the heat during boil treatment or retort treatment of the deep-draw package. And the flange portion (heat-sealed flange portion), which is the bonding portion between the deep-drawing packaging lid material and the deep-drawing packaging bottom material, may curl, and the appearance of the deep-drawing package may be impaired. .. If the 150° C. heat shrinkage ratio (MD/TD or TD/MD) is less than 0.1%, the heat-sealed flange portion is likely to curl, which is not preferable.

Further, the tensile rupture strength in all four directions (0° (MD), 45°, 90° (TD), 135°) of the OPBT film used in the present invention is preferably 170 MPa or more, and 195 MPa or more. It is more preferable that the pressure is 200 MPa or more, and it is still more preferable that the flange portion has rigidity and the flange portion after heat bonding (heat sealed flange portion) is prevented from curling. Is sufficiently obtained, and the secondary processing suitability such as impact resistance, puncture resistance, and printing pitch dimensional stability is remarkably improved. When the tensile strength at break is less than 170 MPa, sufficient pinhole resistance, printability, and curling prevention effect may not be obtained, which is not preferable.
On the other hand, the tensile elongation at break of the OPBT-based film is preferably 50% or more and 150% or less, more preferably 100% or more and 150% or less. If the tensile elongation at break is more than 150% or less than 50%, the OPBT-based film is likely to be broken or stretched during the printing or laminating process, which is not preferable.

In the deep-drawing packaging lid material of the present invention, the thickness of the OPBT-based film is preferably 5 to 100 μm, and more preferably 10 to 30 μm. When the thickness is less than 5 μm, the pinhole resistance of the deep-drawing packaging lid material is low, and there is a possibility that bag breakage is likely to occur when the deep-drawing package is dropped. Further, if the thickness is made excessively thick, the quality is not particularly deteriorated, but the cost is increased.

<Oxygen barrier layer>
The oxygen barrier layer of the cover material for deep-drawing packaging of the present invention imparts oxygen barrier properties, and is, for example, a saponified ethylene-vinyl acetate copolymer (hereinafter also referred to as “EVOH”) layer or aroma. A layer using a coextrusion film containing a group Nylon-based resin layer can be preferably used.
Among them, EVOH preferably has an ethylene content of 3 to 70 mol %. From the viewpoint of imparting excellent oxygen barrier properties, the ethylene content is more preferably 10 to 65 mol%, further preferably 20 to 65 mol%, and further preferably 25 to 60 mol%. Is particularly preferable. If the ethylene content exceeds 70 mol %, the oxygen barrier property may be insufficient.
The degree of saponification of the vinyl ester component is preferably 80% or more, more preferably 95% or more, still more preferably 99% or more. When the saponification degree is less than 80%, the oxygen barrier property may be deteriorated.

As the aromatic nylon-based resin, various resins can be used without particular limitation, and for example, those having an aromatic diamine unit or those having an aromatic dicarboxylic acid unit are preferably used. Specific examples include xylene-based polyamide. The xylene-based polyamide is, for example, a metaxylenediamine homopolymer or a diamine composed of 60% by mass or more, preferably 70% by mass or more of metaxylenediamine and 40% by mass or less, preferably 30% by mass or less of paraxylenediamine. It is a polyamide resin synthesized by a polycondensation reaction of a mixture with an aliphatic dibasic acid having 6 to 12 carbon atoms (for example, adipic acid, sebacic acid, speric acid, undecanedioic acid, dodecanedioic acid, etc.). More specifically, homopolymers such as polymeta-xylene adipamide, polymeta-xylene sebacamide, poly-meta-xylene speramide, meta-xylene/para-xylene adipamide copolymer, meta-xylene/para-xylene pimerami And a metaxylene/paraxylene azamide copolymer, a metaxylene/paraxylene adipamide/sebacamide copolymer, and the like. Among these, crystalline polymeta-xylene adipamide (MXD6) obtained from the polycondensation reaction of meta-xylenediamine and adipic acid is preferable.

Further, in the present invention, the oxygen barrier layer has an inorganic oxide such as aluminum oxide, silicon oxide, titanium oxide, tin oxide, zinc oxide, magnesium oxide, or calcium oxide on the inner surface of the base material layer (OPBT film). Alternatively, it can be formed by a method of providing a vapor deposition film made of aluminum or a mixture thereof. Note that aluminum oxide or silicon oxide is preferably used for the vapor deposition film.
The vapor deposition film can be formed by physical vapor deposition such as vacuum vapor deposition, sputtering, ion plating, or chemical vapor deposition such as plasma chemical vapor deposition, thermochemical vapor deposition, or photochemical vapor deposition. Although the vapor phase growth method can be used, the vacuum deposition method is particularly preferably used from the viewpoint of productivity and cost.

Further, it is also preferable to provide a coating layer made of a barrier resin such as polyvinylidene chloride (hereinafter referred to as K coat) on the surface of the base material layer that is the inside of the OPBT film to provide oxygen barrier properties.

In the deep-drawing packaging lid material of the present invention, the thickness of the gas barrier layer is not particularly limited, but may be about 5 to 100 μm depending on the desired oxygen barrier property.

<Sealant layer>
The sealant layer of the deep-drawing packaging lid material of the present invention is not particularly limited, but unstretched polyethylene-based film, unstretched polypropylene-based film, unstretched polyvinyl chloride film, ethylene-vinyl acetate film, ionomer film, and others. An ethylene copolymer film or the like can be used.
In the deep-draw packaging lid material of the present invention, the thickness of the sealant layer is not particularly limited, but may be about 30 to 100 μm from the viewpoint of pinhole resistance.

(Structure of lid material for deep-drawing packaging)
The lid material for deep-drawing packaging of the present invention is a laminate including the outermost layer, the oxygen barrier layer, and the sealant layer, or a laminate including the outermost layer and the sealant layer. It will be.

The lid material for deep-drawing packaging of the present invention may be provided with a printing layer between the outermost layer and the oxygen barrier layer, or between the outermost layer and the sealant layer, and the outermost layer, the oxygen barrier layer and the sealant layer. One or more intermediate layers such as the oxygen barrier property maintaining layer and the adhesive resin layer may be provided between the respective layers such as the above, or between the outermost layer and the sealant layer.

The method for forming the printing layer is not particularly limited, and examples thereof include methods using known printing methods such as gravure printing, flexographic printing, offset printing, silk printing, letterpress printing, and inkjet printing, alone or in combination.
In the case of the gravure printing method, urethane-based one- or two-component inks can be preferably used as the ink for the printing layer.
The thickness of the print layer is not particularly limited, but is preferably 1 to 5 μm.

The oxygen barrier property maintaining layer suppresses deterioration of the oxygen barrier property, and can be provided on both sides or one side of the oxygen barrier layer.
As the oxygen barrier property maintaining layer, a polyolefin resin layer, a polyamide resin layer, a polybutylene terephthalate resin layer, or the like can be used. Thereby, the lid material for deep-drawing packaging of the present invention can further improve the oxygen barrier property and the pinhole resistance.
The thickness of the oxygen barrier property maintaining layer is not particularly limited, but may be about 5 to 30 μm depending on the required degree of pinhole resistance.

The adhesive resin layer is for adhering each layer, and as the adhesive resin used for the adhesive resin layer, a polyolefin-based adhesive resin can be preferably used and is selected from unsaturated carboxylic acids or derivatives thereof. A modified polyolefin resin grafted with at least one monomer can be preferably used.

In addition, the deep-drawing packaging lid material of the present invention has a usual dry layer formed between the outermost layer, the oxygen barrier layer and the sealant layer, or between the outermost layer and the sealant layer via a laminating adhesive. The adhesive resin layer can be formed by using a laminating method or a method of coating a hot melt adhesive or the like.

The thickness of the adhesive resin layer is not particularly limited, but may be about 2 to 30 μm.

The total thickness of the deep-drawing packaging lid material of the present invention is not particularly limited, but is preferably 40 to 150 μm, and more preferably 40 to 130 μm.

(Manufacturing method of lid material for deep-drawing packaging)
The method for producing the deep-drawing packaging lid material of the present invention is not particularly limited, but after the outermost layer, the oxygen barrier layer and the sealant layer are separately produced, the respective layers are laminated by a dry laminating method, a pressing method or an extrusion laminating method. Or a T-die method or a tubular method to form a composite layer of an oxygen barrier layer and a sealant layer, and then laminate the outermost layer and the composite layer by a dry laminating method, a pressing method or an extrusion laminating method. Method etc. are mentioned.

[Deep drawing package]
A deep-drawing packaging body of the present invention is a packaging body provided with the above-mentioned deep-drawing packaging lid material, and a bottom material having a recess for accommodating contents and a flange portion bonded to the deep-drawing packaging lid material. Is.
The deep-drawing package of the present invention can be produced by bonding the deep-drawing packaging bottom material and the deep-drawing packaging lid material by an adhesive means such as heat sealing.
As an example of the method for producing a deep-drawing package of the present invention, a film (packaging material) is formed into a bottom material for deep-drawing packaging having a desired shape and size by using a deep-drawing molding machine (film supply step and film (Molding step), the contents such as sliced ham are filled therein (contents filling step), and the flange portion of the deep-drawing packaging bottom material and the deep-drawing packaging lid material are heat-sealed (lid material feeding step and Sealing step), vacuum packaging (vacuum packaging step), cooling (cooling step), and cutting (cutting step) to manufacture.

Examples of the bottom material used in the deep-drawing package of the present invention include a bottom material made of a laminate including at least a base material layer made of a thermoplastic resin, a barrier layer, and a seal layer. Layer/sealable resin layer, unstretched polypropylene resin layer/unstretched polyamide resin layer/sealable resin layer, unstretched polypropylene resin layer/unstretched polyamide resin layer/unstretched ethylene-vinyl alcohol copolymer resin layer/sealable resin Layer, unstretched polypropylene resin layer/unstretched polyamide resin layer/unstretched polyamide resin layer/sealable resin layer, and unstretched polypropylene resin layer/saponified ethylene-vinyl acetate copolymer layer/sealable resin layer Laminated products or coextrusion composite films can be used.

The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

The film used for producing the deep-drawing packaging lid material is as follows.
[Outermost layer]
-Homo CPP: unstretched polypropylene film (SC manufactured by Mitsui Chemicals Tohcello Co., SC, thickness 30 μm or 40 μm)
-OPET: Biaxially stretched polyethylene terephthalate film (E5102, manufactured by Toyobo Co., Ltd., thickness 12 μm)
-ONY: Biaxially stretched nylon film (Bonil RX, thickness 15 μm, manufactured by Kojin Film & Chemicals Co., Ltd.)
[Oxygen barrier layer]
Barrier NY: Coextrusion multilayer biaxially stretched gas barrier nylon film of MXD6 nylon and nylon-6 (manufactured by Kojin Film & Chemicals Co., Bonyl SPY, thickness 15 μm)
[Sealant layer]
LLDPE: unstretched linear short-chain branched polyethylene film (Mitsui Chemicals Tohcello Co., Ltd., TUX-HCE, thickness 50 μm)
Reto CPP: unstretched polypropylene film (SC, thickness 60 μm, manufactured by Mitsui Chemicals Tohcello Co., Ltd.)

(Production Example 1: Production of OPBT film)
PBT resin pellets (homotype, melting point=224° C., IV value=1.26 dl/g) dried in a hot air dryer at 140° C. for 5 hours were melted in an extruder under the conditions of cylinder and die temperatures of 210 to 275° C. After kneading, the molten tubular thin film was extruded downward from the annular die. Subsequently, after passing through the outer diameter of the cooling mandrel and folding with a calapser roll, film take-up was performed with a take-up nip roll at a speed of 1.2 m/min. The temperature of the cooling water in direct contact with the molten tubular thin film was 20° C. both inside and outside, and the original fabric cooling rate was 416° C./sec. The unstretched raw fabric had a thickness of 185 μm and a folded diameter of 143 mm, and 1000 ppm of magnesium stearate was previously added as a lubricant into the PBT resin. In the tubular simultaneous biaxial stretching device having the structure shown in FIG. 3, the unstretched raw film 31 formed under the above conditions was conveyed to the nip roll 32 in an atmosphere of 20° C., and longitudinal and transverse simultaneous biaxial stretching was performed. The MD was 3.2 times, the TD was 3.2 times, and the drawing temperature was 60° C. Next, this biaxially stretched film 37 was put into a heat roll type heat treatment equipment and then a tenter type heat treatment equipment, and heat-treated at 210° C. to obtain an OPBT film. The thickness of the film was 15 μm.

With respect to the obtained OPBT film, the 150°C shrinkage was determined according to the following (evaluation method of 150°C shrinkage). The 150°C shrinkage in the MD direction was 1.4%, and the 150°C shrinkage in the TD direction. The rate was 0.8%.
(Evaluation method of 150° C. shrinkage)
A rectangular film cut into 20 cm in each of the MD and TD directions was treated in an atmosphere of 150° C. for 30 minutes, and the length in each direction before and after the treatment was measured to obtain the shrinkage rate.

Regarding the obtained OPBT film, according to the following (evaluation method of tensile strength at break), tensile strength at 0° C. (MD)/45° direction/90° (TD) direction/135° direction The ratio between the maximum value and the minimum value of the tensile breaking elongation and the tensile breaking strength in four directions was determined. The results are shown in Table 1.
(Evaluation method of tensile strength at break)
Tensile rupture strength and elongation are measured by using Orientec-Tensilon (RTC-1210-A) under the conditions of a sample width of 15 mm, a chuck distance of 100 mm, and a pulling speed of 200 mm/min, at 0°C (MD) direction/45° direction. /90° (TD) direction/135° direction, and the tensile rupture strength in each direction, the tensile rupture elongation in each direction, and the tensile rupture strength in four directions, based on the obtained stress-strain curve. The ratio of the maximum value to the minimum value was calculated.

(Production Example 2: Production of bottom material film for deep-drawing packaging)
Bottom material film for deep-drawing packaging 1: polypropylene (PP) (40 μm)/MXD6 (10 μm)/unstretched nylon (CNY) (25 μm)/PP (70 μm) unstretched composite film under a coextrusion annular die A film was formed by a cold water molding method.
Bottom material film for deep-drawing packaging 2: An unstretched composite film of PP (40 μm)/EVOH (10 μm)/PP (70 μm) was formed by a downward cold water molding method using a coextrusion annular die.

<Example 1>
On the surface of the OPBT film (OPBT film having a MD/TD heat shrinkage of 1.4%/0.8%) obtained in Production Example 1, a normal gravure ink composition comprising a normal polyurethane ink was used. A desired print pattern was formed by the gravure printing method. Next, an adhesive for dry lamination (two-component curing type polyurethane) is applied to the printed surface of the OPBT film and the solvent is dried to form an adhesive resin layer (solid content: 3.5 g/m ² ). After bonding a barrier NY (a coextrusion multilayer biaxially stretched gas barrier nylon film of MXD6 nylon and nylon-6) as an oxygen barrier layer on the surface of the adhesive resin layer, LLDPE (sealant layer as a sealant layer was formed on the surface of the oxygen barrier layer by the same procedure. An unstretched linear short-chain branched polyethylene film) was attached to obtain a lid material for deep-drawing packaging.
Further, using a deep-drawing packaging machine (MULTIVAC R535), the bottom-drawing film 2 for deep-drawing packaging is heated to 100° C. and vacuum-pressure air-formed at a pressing time of 0.25 seconds and a processing speed of 6.7 c/min. A bottom material having a molding size of 100 mm×100 mm and a depth of 5 to 30 mm was obtained.
Then, the above-mentioned deep-drawing packaging lid material and the above-mentioned bottom material were combined and heat-sealed under the condition of 150° C.×2 seconds to produce a deep-drawing package.

<Example 2>
Example 1 was repeated except that the MD/TD heat shrinkage ratio was changed to 2.3%/0.4% OPBT film.

<Example 3>
The same procedure as in Example 1 was performed except that the OPBT film having a MD/TD heat shrinkage ratio of 2.4%/0.3% was used.

<Example 4>
The same procedure as in Example 1 was carried out except that the OPBT film having a MD/TD heat shrinkage ratio of 2.3%/0.4% was used.

<Example 5>
Example 1 was repeated except that the OPBT film had a MD/TD heat shrinkage ratio of 2.8%/0.2%.

<Example 6>
Example 1 was repeated except that the MD/TD heat shrinkage ratio was changed to 2.5%/0.1% OPBT film.

<Example 7>
Example 1 was repeated except that the MD/TD heat shrinkage ratio was changed to 3.8%/1.2% OPBT film.

<Example 8>
By the same operation as in Production Example 1, an OPBT film having a MD/TD heat shrinkage ratio at 150° C. of 2.6%/0.3% was obtained. On the surface of the obtained OPBT film, a desired print pattern was formed by a gravure printing method using a usual gravure ink composition comprising a usual polyurethane ink. Next, an adhesive for dry lamination (two-component curing type polyurethane) is applied to the printed surface of the OPBT film and the solvent is dried to form an adhesive resin layer (solid content: 3.5 g/m ² ). LLDPE (unstretched linear short-chain branched polyethylene film) was bonded to the surface of the adhesive resin layer as a sealant layer to obtain a lid material for deep-drawing packaging.
Further, using a deep-drawing packaging machine (MULTIVAC R535), the bottom-drawing film 2 for deep-drawing packaging is heated to 100° C. and vacuum-pressure air-formed at a pressing time of 0.25 seconds and a processing speed of 6.7 c/min. A bottom material having a molding size of 100 mm×100 mm and a depth of 5 to 30 mm was obtained.
Then, the above-mentioned deep-drawing packaging lid material and the above-mentioned bottom material were combined and heat-sealed under the condition of 150° C.×2 seconds to produce a deep-drawing package.

<Example 9>
In Example 2, LLDPE (unstretched linear short-chain branched polyethylene film) was changed to Leto CPP (unstretched polypropylene film), and deep-draw packaging bottom material film 2 was changed to deep-draw packaging bottom material film 1. The procedure was the same as in Example 2 except for the above.

<Example 10>
In Example 8, the MD/TD heat shrinkage rate was changed to 2.4%/0.2% OPBT film, and LLDPE (unstretched linear short-chain branched polyethylene film) was replaced with Leto CPP (unstretched polypropylene film). The same procedure as in Example 8 was performed, except that

<Example 11>
In Example 2, K-OPBT (a film having a coding layer made of polyvinylidene chloride on an OPBT film, having a thickness of 15 μm) was used as the outermost layer and oxygen barrier layer, and the bottom material film 2 for deep-drawing packaging was made deep. Example 2 was repeated except that the bottom film 1 for squeezed packaging was changed.

<Example 12>
In Example 10, a transparent vapor-deposited OPBT (a film obtained by vapor-depositing silica on an OPBT film having a MD/TD heat shrinkage of 2.3%/0.3%, a thickness of 15 μm) was used as the outermost layer and oxygen barrier layer. The same procedure as in Example 10 was carried out except that the above was carried out.

<Comparative Example 1>
The same procedure as in Example 1 was performed except that the OPBT film having a thermal shrinkage of 3.6%/0.1% was used.

<Comparative example 2>
Example 1 was repeated except that the OPBT film had a heat shrinkage of 6.0%/4.0%.

<Comparative example 3>
Example 2 was carried out in the same manner as in Example 2 except that the MD/TD stretch ratio was changed to 3.0 times/2.5 times.

<Comparative example 4>
Example 9 except that the MD/TD stretch ratio was changed to 2.8 times/2.5 times.
I went in the same way.

<Comparative Example 5>
Using a blend of PBT resin and PET resin at a ratio of 50/50, stretching was performed after film formation by the production method of Production Example 1, but the stretching was not stable, and a stretched film could not be obtained.

<Comparative example 6>
In Example 1, it carried out like Example 1 except having changed the outermost OPBT film into homo CPP (thickness 30 micrometers).

<Comparative Example 7>
The same procedure was performed as in Example 9 except that the outermost OPBT film was changed to homo CPP (thickness: 40 μm).

<Comparative Example 8>
The same procedure as in Example 1 was repeated except that the OPBT film (thickness: 12 μm) was used as the outermost OPBT film.

<Comparative Example 9>
Example 1 was repeated except that the outermost OPBT film was changed to an ONY film (thickness: 15 μm).

For each deep-drawing package and each deep-drawing packaging lid material, whether curl occurs after boil treatment or retort treatment, whether heat seal part is whitened, gloss value, gloss, print pitch deviation, and heat seal The rear cover material tension was evaluated. Each evaluation procedure is shown below. The results are shown in Table 1.

(Curl after boil treatment)
The prepared package was boiled with boiling water for 30 minutes, immediately placed on a horizontal table and observed, and the four curls of the heat-sealed flange portion of the package had the largest curl. The height from the horizontal table was measured as the "curl maximum height", and when the curl maximum height was 5 mm or less, it was marked with ◯, and when it exceeded 5 mm, it was marked with x.
(Curl after retort treatment)
The prepared deep-drawn package is placed in a retort kettle and retort-treated at a temperature of 135° C. and a pressure of 3.1 kg/cm ² for 30 minutes, immediately placed on a horizontal table for observation, and heat-sealing of the package. Of the four corners of the flange, the height of the largest curl from the horizontal base was measured as the "curl maximum height". When the curl maximum height is 5 mm or less, it is ○, and when it exceeds 5 mm, it is ×. And
(Whitening of heat seal after heat sealing)
After the heat-sealing of the deep-drawing packaging lid material and the deep-drawing packaging bottom material at a temperature of 160° C., the presence or absence of whitening at the heat-sealed portion was evaluated. When there was no whitening, it was rated as ◯, and when whitening occurred, it was rated as x.
(Gloss value)
With respect to the lid material for deep-drawing packaging, the gloss value on the outermost layer side was measured according to JIS K7105.
(Glossy visual inspection)
The glossiness was visually evaluated from the outermost layer side of the deep-drawing packaging lid material. When there was gloss, it was marked with O, and when it was not gloss, it was marked with X.
(Print pitch deviation evaluation)
On the deep-drawing packaging lid material, eight colors were sequentially printed by gravure printing. The pitch dimensional accuracy of the printed pattern is ◯ when all the dimensional differences from the second and subsequent colors are within ±0.1% with respect to the first color, and 0.1% even for one color. When it exceeded, it was marked as x.
(Cover material after heat sealing)
Regarding the prepared deep-drawing package, when the slack was not seen in the lid material, it was marked with O, and when the slack was seen in the lid material, it was marked with X.

As shown in Table 1, in a deep-drawing packaging cover material, a laminate including an outermost layer made of an OPBT film or an OPBT-based film, an oxygen barrier layer and a sealant layer, or a laminate including the outermost layer and a sealant layer. The deep drawing has excellent glossiness and printing pitch dimensional accuracy, and the heat-sealed flange part does not easily curl and the heat-sealed part does not whiten after boiling or retorting. It has been found that a packaging lid can be obtained.

ADVANTAGE OF THE INVENTION According to the lid material for deep-drawing packaging containing OPBT of the present invention, printing can be performed in the same manner as OPET with good printing pitch dimension accuracy without impairing gloss, and heat sealing is performed even after boil processing or retort processing. Since the flange part that has been curled and the heat-sealed part are less likely to be whitened, it is possible to provide a thin film that does not reduce the commercial value, and a lid material for deep-drawing packaging that enables waste volume reduction. is there.

10 Deep Drawing Package 11 Deep Drawing Packaging Cover Material 12 Deep Drawing Packaging Bottom Material 13 Flange Part 14 Food Product 21 Outermost Layer 22 Oxygen Barrier Layer 23 Sealant Layer 31 Unstretched Raw Fabric 32 Nip Roll 33 Heater 34 Cooling Ring 35 Calapsa Roll 36 Nip Roll 37 Biaxially stretched film

Claims (5)

An outermost layer made of a biaxially stretched polybutylene terephthalate film, which is made of either a polybutylene terephthalate resin or a polyester resin composition in which a polyethylene terephthalate resin is blended in a range of 30% by mass or less with respect to the polybutylene terephthalate resin; A lid material for deep-drawing packaging, comprising a laminate including an oxygen barrier layer and a sealant layer, or a laminate including the outermost layer and a sealant layer. The biaxially stretched polybutylene terephthalate-based film is a film having a heat shrinkage rate of 0.1% to 5% at 150° C. in the longitudinal direction (MD) and the width direction (TD). Deep-drawing packaging lid material. The biaxially stretched polybutylene terephthalate film has a ratio (MD/TD) of 150° C. heat shrinkage in the longitudinal direction (MD) to 150° C. heat shrinkage in the width direction (TD), or the biaxially stretched polybutylene terephthalate. A film having a ratio (TD/MD) of a heat shrinkage rate of 150° C. in the width direction (TD) and a heat shrinkage rate of 150° C. in the longitudinal direction (MD) of the system film of 1.0 to 30.0. The lid material for deep-drawing packaging according to claim 1 or 2. The biaxially stretched polybutylene terephthalate film is a film having a tensile breaking strength of 170 MPa or more in all four directions (0° (MD), 45°, 90° (TD), 135°). The lid material for deep-drawing packaging according to any one of claims 1 to 3. A deep-drawing packaging body comprising: a deep-drawing packaging lid material; and a deep-drawing packaging bottom material having a recessed portion for accommodating contents and a flange portion laminated with the deep-drawing packaging lid material,
A deep-drawing packaging body, wherein the deep-drawing packaging lid material is the deep-drawing packaging lid material according to any one of claims 1 to 4.

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