JP4381865B2 - Deep drawn package - Google Patents

Description

  The present invention mainly relates to a high-barrier type deep-drawing vacuum packaging of food, and relates to a package that performs boil sterilization after vacuum packaging, such as a hamburger.

  Conventionally, as a film for boiling in deep drawing vacuum packaging, Ny / EVOH / seal and PP // EVOH / Ny / seal films are used for the bottom material, and CPP // transparent deposited PET is used for the cover material. // A film with a structure of a seal was mainly used.

  In the specification of the present invention, the composition of the film is indicated by including / in the case of co-extrusion, // in the case of dry lamination, and [] in the case of co-extrusion biaxially stretched product.

  However, since the Ny outer layer film of the bottom material expands and contracts due to the influence of hot water during boiling, there is a problem that the flange portion (the portion sealed by the surface) of the pack product is largely curled. Even when a PP // EVOH / Ny / seal layer film is used as the bottom material, a PP // transparent vapor-deposited PET // seal layer lid material is used as the cover material, so that other unstretched films are boiled. There is a problem that the flange portion after the boil curls to the bottom material side because the transparent vapor-deposited PET of the lid material does not shrink at all while the medium shrinks slightly.

This application includes the following inventions.

(1) In deep-drawing packaging, at least the bottom material is a PP / EVOH / Ny / seal layer or PP / Ny / EVOH / seal layer laminated in this order, and the lid material is at least PP / / [Biaxially stretched 6Ny / MXDNy / 6Ny] // sealing layer or PP / [biaxially stretched 6Ny / EVOH / 6Ny] // sealed layer in the order of 70 μm to 200 μm and [two Wrapped with a film having a shrinkage ratio of 1 to 3% in 95 ° C. × 5 minutes of hot water of [axially stretched 6Ny / MXDNy / 6Ny] or [biaxially stretched 6Ny / EVOH / 6Ny] Deep drawn packaging.
However, in the laminated film, the type of film is indicated by / is co-extruded, // is dry laminated, [] is co-extruded biaxially stretched product, PP is polypropylene, EVOH is ethylene-vinyl acetate copolymer Saponification, 6Ny is 6-nylon, MXDNy is nylon having metaxylenediamine as an amine component, and Ny is 6-nylon or 6-66 nylon.

  (2) The deep drawn package according to (1), wherein the thickness of the PP outer layer of the bottom material film is 10 to 50% of the total thickness of the bottom material.

  (3) The deep drawn package according to (1), wherein the thickness of the PP outer layer of the lid material film is 10 to 50% of the total thickness of the lid material.

  (4) The deep drawn package according to (1), wherein the PP outer layer of the bottom film has a melting point of 140 to 170 ° C.

  (5) Melting | fusing point of PP outer layer of a lid | cover material film is 150-170 degreeC, The deep drawn package as described in (1) characterized by the above-mentioned.

  (6) The deep-drawn package according to (1), wherein the melting point of the resin most contained in each of the sealing layers of the bottom material and the lid material is 80 to 125 ° C.

  (7) The deep drawn package according to (1), wherein the bottom material is a coextruded film.

  (8) The deep-drawn packaged body according to any one of (1) to (8), wherein boiling is mainly performed for sterilization at a temperature of 70 to 100 ° C. after packaging.

  The present invention has found a deep-drawn package that can solve the above-mentioned problems, and the above object can be achieved by the following means.

  That is, in deep-drawn packaging, a film having a layer thickness of 50 to 300 μm laminated at least in the order of PP / EVOH / Ny / seal or PP / Ny / EVOH / seal is used as a bottom material, and at least CPP // [2 70 μm to 200 μm films laminated in the order of axial stretch 6Ny / MXDNy / 6Ny] // seal or CPP // [biaxial stretch 6Ny / EVOH / 6Ny] // seal (where [biaxial stretch 6Ny / MXDNy / 6Ny], [biaxially stretched 6Ny / EVOH / 6Ny] at 95 ° C. for 5 minutes in hot water at a shrinkage of 1 to 3%) It is to propose. Here, the outer layer PP thickness of the bottom material film is 10 to 50% of the total thickness of the bottom material, the outer layer CPP thickness of the lid material film is 10 to 50% of the total thickness of the lid material, The melting point of the outer layer PP of the material film is 140 to 170 ° C., the melting point of the outer layer CPP of the lid material film is 150 to 170 ° C., and the melting point of the resin most contained in the bottom layer and the sealing layer of the lid material. Is 80 to 125 ° C., the bottom material is a coextruded film, and after packaging, boiling is mainly performed at a temperature of 70 to 100 ° C. for sterilization.

  Hereinafter, the present invention will be described in more detail.

  The bottom film of the present invention needs to be laminated in the order of PP / EVOH / Ny / seal layer or PP / Ny / EVOH / seal layer, where the outer layer is PP. Compared to EVOH and Ny resin, which have high hygroscopicity, PP resin has extremely low hygroscopicity, and it is very useful as an outer layer resin for this application that it absorbs moisture during boiling and does not plasticize or cause large dimensional changes. Because there is. Furthermore, since the surface hardness is higher than that of LL or HDPE, it is difficult to be damaged, has rigidity, and is easily glossy. Therefore, it is very suitable as an outer layer resin for such applications as compared with other polyolefin resins.

  PP may be homo PP, random copolymer PP with ethylene (hereinafter random PP), or block copolymer PP with ethylene (hereinafter block PP), but it has a melting point of 140 to 200 from the viewpoint of heat resistance, rigidity, gloss, and transparency. Homo PP and random PP at 170 ° C. are preferred.

  EVOH is not particularly limited in the type of ethylene-vinyl acetate copolymer saponified resin, but has an ethylene content of 29 to 47 mol% (preferably 32 to 44 mol%) and a saponification degree of 90 mol% or more (preferably 95 mol). % Or more) can be suitably used in terms of coextrusion suitability and film strength.

  Although the kind of polyamide resin is not particularly limited, 6 nylon and 6-66 copolymer nylon can be suitably used in terms of strength and adhesive strength with an adhesive resin. The two types of nylon are preferable because they have strong interlayer adhesion strength with the ethylene-vinyl acetate copolymer saponified resin layer.

  Since PP / EVOH or PP / Ny and EVOH / seal or Ny / seal layers cannot be bonded by coextrusion as they are, it is necessary to interpose an adhesive resin (hereinafter referred to as AD). The AD used here is not particularly limited as long as a PP layer, a seal layer, an EVOH layer, a polyamide resin layer and the like can be bonded to a necessary strength, but a polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof is used. Examples of the unsaturated carboxylic acid preferably used include acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid and the like. Also, esters and anhydrides of these unsaturated carboxylic acids can be used, and as derivatives, methyl acrylate, methyl methacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, butyl methacrylate, vinyl acetate, glycidyl acrylate, Glycidyl methacrylate, acrylamide, methacrylamide, sodium acrylate and the like can be used. In addition, as the polyolefin resin, polyethylene, polypropylene, polybutene, and copolymers thereof, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, and the like can be used. For example, the product name Admer manufactured by Mitsui Chemicals, Inc. is commercially available and is preferably used.

  Note that the EVOH and Ny layers may be provided with AD or the like or two or more layers in consideration of improvement in pinhole resistance and oxygen barrier properties. In short, it may be an intermediate layer between the outermost layers of PP and the seal layer.

  The total thickness of the bottom material film needs to be 50 to 300 μm, preferably 60 to 250 μm, and more preferably 70 to 200 μm. When the total thickness is less than 50 μm, the bottom material becomes weak and curls tend to occur. Conversely, when the thickness exceeds 300 μm, the waist becomes too stiff in vacuum packaging, resulting in a very pack appearance such as generation of hard wrinkles. The problem of worsening occurs and is not preferable.

  Here, the ratio of the PP thickness is suitably 10 to 50% of the total thickness, and if it is less than 10%, the waist becomes too weak and the curling prevention effect becomes weak. On the other hand, if it exceeds 50%, the waist becomes too hard, which is not preferable because the pinhole resistance (particularly under refrigeration and freezing) of the film is lowered.

  The bottom film can also be produced by dry laminating CPP to a coextruded film that is at least EVOH / Ny / seal or Ny / EVOH / seal, but CPP monolayer films are generally deep drawn When molding is performed, the surface tends to become dull, and the pinhole resistance is lowered because the entire surface is hardened by dry laminating. Therefore, it is preferable to manufacture all the layers including the outer layer PP by coextrusion. . It should be noted that it is desirable to add a nucleating agent such as sorbitol or metal salt to the outer PP layer for the purpose of suppressing the growth of spherulites and improving transparency and gloss.

  The lid material film should be laminated at least in the order of CPP // [biaxially stretched 6Ny / MXDNy / 6Ny] // seal layer or CPP // [biaxially stretched 6Ny / EVOH / 6Ny] // seal layer. However, the reason why it is the outer layer of the CPP here is the same reason as in the case of the bottom material. In particular, when the outer layer resin of both the bottom material and the lid material is made of PP, the curl is in a good direction. CPP is an extruded film of PP.

PP may be homo PP, random copolymer PP with ethylene (hereinafter random PP), or block copolymer PP with ethylene (hereinafter block PP), but it has a melting point of 150 to 150 from the viewpoint of heat resistance, rigidity, gloss, and transparency. Homo PP and random PP at 170 ° C. (more preferably 155 ° C. to 170 ° C.) are suitable. In the case of a lid material, the heat plate of the heat seal is heated in contact with the outer layer resin side of the lid material, that is, the PP surface side, so if the heat resistance of PP is low, it will stick to the heat plate and the seal will not work well. End up. Therefore, it is most preferable to use homo PP having a melting point of 160 ° C to 170 ° C. The CPP thickness ratio is suitably 10 to 50% of the total thickness. If it is less than 10%, the waist becomes weak, and curling after boiling tends to be insufficient. Conversely, if it exceeds 50%, the waist becomes too hard, and pinholes and cracks may occur. Because.

  [Biaxial stretching 6Ny / MXDNy / 6Ny] and [Biaxial stretching 6Ny / EVOH / 6Ny] of the intermediate layer are generally films of about 12 to 25 μm, but the shrinkage rate in hot water at 95 ° C. for 5 minutes is 1 It must be ˜3%. This is because if a PET film that does not shrink during boiling is used, it cannot follow the shrinkage of the bottom material and curls the bottom material. Therefore, it is considered that a shrinkage rate of 1 to 3% is preferable. However, if the shrinkage rate is less than 1%, the shrinkage rate is insufficient, and the bottom material side curl tends to occur. If the shrinkage rate exceeds 3%, the lid material tends to shrink too much. Because it becomes. In addition, if the lid for deep-drawing packaging is composed only of unstretched film, the lid will be stretched by the heat of the seal, preventing the problem of wrinkling during sealing. In order to do this, it is necessary to dispose a biaxially stretched film in which one layer is difficult to stretch on the lid. When printing is performed, the biaxially stretched product is advantageous because it has a higher tensile elastic modulus, and the intermediate layer is also effective in this respect. Representative examples of the intermediate layer include Super Neil (manufactured by Mitsubishi Plastics) and Embron (manufactured by Unitika).

  The CPP, intermediate layer, and seal layer of the lid material can be laminated by a dry lamination method.

  The lid layer needs to have a layer thickness of 70 μm to 200 μm. However, if the thickness is less than 70 μm, the curl suppressing force is weakened. Conversely, if the thickness exceeds 200 μm, the seal temperature is not easily transmitted to the seal interface. The problem that sealing becomes difficult occurs.

  Accordingly, the seal layer is suitably of a type that can be sealed at a low temperature, and the bottom and lid sealing layers are preferably based on those having a melting point of 80 to 125 ° C. (more preferably 100 to 120 ° C.). This is because if the temperature is less than 80 ° C., there may be a problem of heat resistance during boiling, and if the temperature exceeds 125 ° C., the sealing layer is difficult to melt, and the lid outer layer CPP may be melted first. This is because For this reason, LLDPE-based PE resins having a relatively low melting point are preferably used. In addition, an easy peel can be imparted to the seal layer, but in this case as well, it is desirable that the maximum proportion of the resin constituting the surface layer be within the melting point range.

  The packaging body of the present invention in which the outer layer resin of the lid material and the bottom material is preferentially defined and the shrinkage rate in hot water is particularly defined in the intermediate layer of the lid material is curled in boil sterilization at 70 to 100 ° C. Demonstrate the effect of preventing. Here, if the temperature is less than 70 ° C., the temperature is low and curling is unlikely to occur even if it is not the film of the present invention, so that the effect of the present invention is difficult to understand.

  The film of the present invention can prevent curling after boiling and can print with a stable pitch on the lid, so that the display effect when packaging foods and lining them up in stores is very good and can greatly contribute to sales promotion It has become.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

The films of Examples 1 to 4 and Comparative Examples 1 to 5 were formed by the coextrusion method or a combination of the coextrusion method and the dry laminating method and evaluated. (/ Indicates coextrusion, // indicates dry lamination, [] indicates coextrusion biaxially stretched product)
The raw materials used are shown below.
PP-1: Propylene / ethylene random cohomopolymer resin. (Melting point determined by DSC: 155 ° C.)
PP-2: Homopolypropylene extruded film. (Melting point determined by DSC: 164 ° C.)
EVOH: EVAL EP-E153B (manufactured by Kuraray Co., Ltd.)
Ny: 6-nylon
Novamid 1030 (Mitsubishi Engineering Plastics Co., Ltd.)
AD: Admer NF556 (Mitsui Chemicals, Inc.)
LLDPE: More Tech 0138N (manufactured by Idemitsu Petrochemical Co., Ltd.)
Transparent vapor-deposited PET: Barrier Lock 1011MG-CW (manufactured by Toyo Metallizing Co., Ltd.)
EVA: Novatec EVA LV120 (manufactured by Nippon Polyethylene Co., Ltd.), Tm 109 ° C
MXDNy: Reny 6007 (Mitsubishi Gas Chemical Co., Ltd.)
6Ny: Novamit 1020 (Mitsubishi Engineering Plastics Co., Ltd.)
[Biaxial stretching 6Ny / MXDNy / 6Ny] (each thickness is 5.5 / 4 / 5.5 μm)
[Biaxial stretching 6Ny / EVOH / 6Ny] (each thickness is 5.5 / 4 / 5.5 μm)
OPP: Biaxially stretched PP film The numerical value below each layer represents the thickness of the layer in μm.
Example 1
Bottom material: PP-1 / AD / EVOH / Ny / AD / LLDPE
30 10 20 20 10 40
Lid material: PP-2 // [biaxially stretched 6Ny / MXDNy / 6Ny] // LLDPE
30 15 40
(Example 2)
Bottom material: PP-1 / AD / EVOH / Ny / AD / LLDPE
30 10 20 20 10 40
Lid: PP-2 // [Biaxially stretched 6Ny / EVOH / 6Ny] // LLDPE
30 15 40
(Example 3)
Bottom material: PP-1 / AD / EVOH / AD / Ny / AD / EVA
30 10 20 10 20 10 30
Lid: PP-2 // [Biaxial stretching 6Ny / MXDNy / 6Ny] // EVA
30 15 40
EVA film is Tamapoly Co., Ltd. film SB-5 (thickness 40 μm)
(Example 4)
Bottom material: PP / AD / Ny / EVOH / AD / LLDPE
30 10 20 20 10 40
Material: PP-2 // [biaxially stretched 6Ny / MXDNy / 6Ny] // LLDPE
30 15 40
(Comparative Example 1)
Bottom material: Ny / AD / Ny / EVOH / AD / LLDPE
10 10 20 20 10 60
Lid material: PP-2 // [biaxially stretched 6Ny / MXDNy / 6Ny] // LLDPE
30 15 40
(Comparative Example 2)
Bottom material: PP-1 / AD / EVOH / Ny / AD / LLDPE
30 10 20 20 10 40
Lid: PP-2 // [Transparent Deposition PET] // LLDPE
30 12 40
(Comparative Example 3)
Bottom material: PP-1 / AD / EVOH / Ny / AD / LLDPE
30 10 20 20 10 40
Lid: OPP // [Biaxial stretching 6Ny / MXDNy / 6Ny] // LLDPE
30 15 40
(Comparative Example 4)
Bottom material: PP-1 / AD / EVOH / Ny / AD / LLDPE
30 10 20 20 10 40
Lid material: PP-2 // [biaxially stretched 6Ny / MXDNy / 6Ny] // LLDPE
200 15 40
(Comparative Example 5)
Bottom material: PP-1 / AD / EVOH / Ny / AD / LLDPE
30 10 20 20 10 40
Lid: PP / AD / EVOH / Ny / AD / LLDPE
30 10 20 20 10 40
<Evaluation method>
Each of the above films was packed using a deep drawing packaging machine FV6300 (manufactured by Omori Machine Industry Co., Ltd.).
(1) Packaging conditions-Molding temperature: 95 ° C
・ Drawing depth: 20mm
・ Contents: 120g hamburger (approx. Φ95mm)
・ Package size: 120mm x 140mm
(2) Boil conditions • 95 ° C. × 20 minutes (3) Contents of evaluation • Sealing property: The lid material was not taken on the hot plate, and it was sealed without any problem.

    -Wrinkles of the lid material: At the time of sealing, the case where the lid material was wrinkled was rated as x, and the case where there was no problem was marked as ◯.

    -Curling property: After boiling, the case where the average value of curling at the four corners of the flange portion was 10 mm or less was evaluated as ◯, and the case where it exceeded 10 mm was rated as x.

  The experimental results are shown in Table 1.

Claims (8)

In deep-drawn packaging, at least a PP / EVOH / Ny / seal layer or a PP / Ny / EVOH / seal layer laminated in the order of PP / EVOH / Ny / seal layer is used as a bottom material, and at least PP // [2 A film of 70 μm to 200 μm laminated in the order of axial stretching 6Ny / MXDNy / 6Ny] // sealing layer or PP // [biaxial stretching 6Ny / EVOH / 6Ny] // sealing layer, and [biaxial stretching 6Ny / MXDNy / 6Ny] or [biaxially stretched 6Ny / EVOH / 6Ny], which is packaged using a film having a shrinkage rate of 1 to 3% in hot water at 95 ° C. for 5 minutes Packaging body.
However, in the laminated film, the type of the film is indicated by / is co-extrusion, // is dry laminate, [] is co-extruded biaxially stretched product, PP is polypropylene, EVOH is ethylene-vinyl acetate copolymer Saponified product, 6Ny is 6-nylon, MXDNy is nylon having metaxylenediamine as an amine component, and Ny is 6-nylon or 6-66 nylon.   The deep drawn package according to claim 1, wherein the thickness of the PP outer layer of the bottom material film is 10 to 50% of the total thickness of the bottom material.   2. The deep-drawn package according to claim 1, wherein the thickness of the PP outer layer of the lid material film is 10 to 50% of the total thickness of the lid material.   The deep drawn package according to claim 1, wherein the PP outer layer of the bottom film has a melting point of 140 to 170 ° C.   The deep-drawn package according to claim 1, wherein the melting point of the PP outer layer of the lid film is 150 to 170 ° C.   The deep-drawn package according to claim 1, wherein the melting point of the resin most contained in each of the bottom layer and the lid sealing layer is 80 to 125 ° C.   The deep-drawn package according to claim 1, wherein the bottom material is a coextruded film. The deep-drawn packaged body according to any one of claims 1 to 7, wherein after packaging, boiling is performed mainly at a temperature of 70 to 100 ° C for the purpose of sterilization.