JP3334486B2 - Packaging material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging material for packaging a hydrated material, and more particularly to a packaging material comprising a composite film using a polyester-based heat-adhesive resin on the side in contact with the contents.

[0002]

2. Description of the Related Art Conventionally, polyethylene (P) has been used as a heat-adhesive resin for a composite film used as a packaging material.
E) and polyolefin-based resins such as polypropylene (PP).

[0003] However, in the case of a packaging material using such a polyolefin-based heat-adhesive resin, when the contents are, for example, juice or the like, the adsorption of the aroma component is large,
Furthermore, there are many drawbacks such as low-molecular-weight components such as olefin odors being eluted, which causes taste change and unusual odor. When PP is used as the polyolefin, P
Since the use of an antioxidant is inevitable to prevent the P from being oxidized and deteriorated, for example, when the antioxidant is used in food packaging, there is a problem that the antioxidant is eluted and transferred to contents such as food.

For this reason, polyester-based heat-adhesive resins which do not have the above-mentioned disadvantages have recently been used as heat-adhesive resins for packaging materials for foods or medicines.

[0005]

However, when the polyester-based heat-adhesive resin as described above is used, the disadvantages of the polyolefin-based resin are certainly improved,
Such a packaging material is inferior in flexibility due to the polyester resin itself, and particularly when subjected to heat treatment such as retort sterilization and boil sterilization, crystallization of the polyester resin is promoted and the resin becomes brittle, so that it is resistant to There was a problem that the impact strength was not sufficient, and it could be applied only to soft packaging.

Japanese Patent Application Laid-Open No. 1-182255 discloses a packaging material using a polybutylene terephthalate resin film. However, such a packaging material has a problem that when it is subjected to a retort treatment, it is whitened and the appearance is impaired. Heat sealability is also poor.

The present invention has been made in view of the above-mentioned problems of a packaging material comprising a composite film in which a polyester-based thermo-adhesive resin is used on the side in contact with the contents. Even if heat treatment such as hot filling, boiling sterilization, retort treatment, etc., in which the adsorption and sorption of the active ingredient and the like are low and the temperature is higher than the glass transition temperature of the polyester-based thermo-adhesive resin, are performed, the hydrolysis of the polyester-based thermo-adhesive resin is performed. Another object of the present invention is to provide a packaging material which does not cause deterioration in physical properties such as oligomer elution and molecular weight reduction, and taste inhibition.

[0008]

According to the present invention, an acid value of 4.0 m is formed as a sealant layer on a side of at least one layer of a base film composed of a film or a sheet in contact with the contents.
gKOH / g or less, more preferably 3.8 mgKOH
/ G or less, provided with a polyester resin film layer. As described above, the packaging material of the present invention has an acid value of 4.0 m as a sealant layer.
gKOH / g or less, more preferably 3.8 mgKOH
/ G or less, less adsorption and sorption of scent components, active ingredients, etc., and physical properties such as drop strength even after heat treatment such as retort treatment at or above the glass transition temperature Does not decrease.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The acid value of the polyester resin used as the sealant layer of the present invention must be 4.0 mgKOH / g or less, more preferably 3.8 mgKOH / g or less. When the acid value is 4.0 mgKOH / g or more, when heat treatment such as boil sterilization is performed, thermal decomposition is easily promoted, and as a result, thermal degradation is easily caused. When heat deterioration proceeds, the resin whitens and loses its appearance when subjected to heat treatment such as boiling sterilization. In addition, the IV (intrinsic viscosity) is reduced, the molecular weight of the polymer is reduced, and the tensile strength of the film is reduced, and when the pouch is formed, impact resistance such as drop strength is reduced.

The above polyester resin can be easily obtained by using a known polyester resin synthesizing means.

The thickness of the polyester resin film of the present invention is at least 40 μm, preferably 50 to 80 μm in consideration of impact resistance and the like.

As the composite film constituting the packaging material of the present invention, specifically, a composite film obtained by laminating a base film comprising at least one film or sheet on the polyester resin of the present invention, Material films include polyolefin resins such as polyethylene and polypropylene, polyethylene terephthalate and other polyester resins, polyvinyl chloride, polystyrene,
Stretched or unstretched resin layer commonly used such as polycarbonate and polyamide, resin layer with excellent gas barrier properties such as polyvinylidene chloride, polyvinyl alcohol and polyacrylonitrile, metal foil, metal and metal oxide, inorganic oxide An article or a thin film layer of an inorganic compound, further, a paper, a nonwoven fabric, or the like may be used alone or a plurality of layers depending on the purpose. More specifically, aluminum foil / polyester resin film, stretched nylon film, polyvinylidene chloride resin layer / stretched nylon film, stretched nylon film / aluminum foil /
Examples of the structure include a polyester resin film and polypropylene / polyvinyl alcohol / polypropylene.

The aluminum foil has a thickness of 7 to 15 μm.
m is generally used, and as an adhesive used for dry lamination with the polyester resin of the present invention or the outermost layer polyester, for example, a polyester adhesive (Takelac A515; manufactured by Takeda Pharmaceutical Co., Ltd., etc.) ).

[0014] The packaging material of the present invention is most suitable as a packaging material for food contents including beverages, especially for hydrated foods such as porridge, porridge, baby food and the like.

The packaging material of the present invention includes food packaging films used for liquid pouches and retort pouches requiring impact resistance, and food containers such as lids for liquid containers requiring impact resistance. Examples thereof include a film for a lid material, a haptic agent, or the like, in which the active ingredient such as a capping agent is remarkably adsorbed and sorbed on a packaging film, or a film for a pharmaceutical packaging, which is used for an expensive medicinal ingredient that requires a reduced amount of use.

[0016]

EXAMPLES Examples of the present invention will be described below more specifically. <Example 1> After a polyester resin or the like having the composition shown in Table 1 was polymerized and pelletized, it was formed into a film by a T-die method or an inflation method, or laminated with a base film by a knee ram method or an extrusion method. In this manner, a packaging material having the following configuration was produced. Biaxially stretched polyethylene terephthalate film (12 μm thickness) / aluminum foil (9 μm thickness) / Polyester resin film of the present invention (60 μm thickness)

Using the obtained packaging material, 130 mm × 1
A bag having a size of 70 mm was prepared, filled with 200 ml of mineral water, and heat-sealed.
After a retort treatment at 0 ° C. for 30 minutes, a sensory evaluation and a drop test were performed by the following methods. The acid value was measured for each polyester resin formed into a film, and the IV was measured for each of the polyester resin film portions before and after the retort treatment of the produced bag. Table 2 shows the results. Sensory evaluation; CP of contents (mineral water)
Those of P and perform a pair comparison, tested by χ ² test method. : Taste better than CPP at 5% risk rate △: No significant difference ×: CPP better taste at 5% risk rate Drop test The impact resistance is evaluated by the number of drops. Acid value; dissolve sample in purified benzyl alcohol,
It is titrated with a 0.1N KOH benzyl alcohol solution and determined from the consumption. IV; sample was phenol / tetrachloroethane = 6
混合 (weight ratio) in a mixed solvent at 20 ° C. IV change amount: The IV before and after the retort sterilization treatment is measured, and the change amount is determined. : 0-0.05 Little decrease observed; Δ: 0.05-0.1 Slight decrease observed ×: 0.1 or more large decrease

[0018]

[Table 1]

[0019]

[Table 2]

Considering from Tables 1 and 2, Example 1 and Comparative Example 1 and Example 2 and Comparative Example 2 have different acid values even though the polyester resin composition is the same. This means that the polyester resin is exposed to a high-temperature atmosphere for a long time during the polycondensation step or during the heat dissolution during film formation, thereby promoting the thermal decomposition of the polyester resin and increasing the carboxyl end groups, that is, the increase in the acid value. An increase occurs. In particular, it shows that thermal decomposition is likely to occur when the polycondensation time is long in the polycondensation step or when the time until pelletization from the polymerization vessel is long. In addition, a polymer with a high acid value that has been thermally degraded
It has the property of being more easily thermally degraded with respect to the subsequent heat history than the polymer having a low acid value. Therefore, filming,
Further, the polyester resin used for the retort pouch sealant material or the like which is subjected to retort sterilization treatment or receives a heat history many times needs to be resistant to thermal deterioration, that is, have a low acid value.

[0021]

As described in detail above, the acid value is 4.0.
mgKOH / g or less, more preferably 3.8 mgKOH
By using a polyester resin of less than / g, there is little adsorption and sorption of active ingredients and aroma components of the contents, there is no elution of additives such as low molecular weight components and antioxidants, and only impact resistance is excellent. In addition, it is possible to provide a packaging material that does not cause poor taste and whitening even when retort treatment is performed.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-325245 (JP, A) JP-A-3-96345 (JP, A) JP-A-7-304885 (JP, A) JP-A-6-304 286091 (JP, A) JP-A-51-56883 (JP, A) JP-B-51-48513 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 27/36 C08G 63 / 00

Claims (1)

(57) [Claims] An acid value of 4.0 mgKOH / g or less as a sealant layer on a side of at least one layer of a base film composed of a film or sheet which is in contact with the contents.
A packaging material characterized by comprising a polyester resin film layer.