JP2007176054A - Gas-barrier package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic film which is excellent in gas-barrier properties after vapor deposition by having excellent adhesion to an inorganic oxide layer and which does not deteriorate the adhesion and the gas-barrier after the filling of contents, and a package using the plastic film. <P>SOLUTION: An easily-adhesive layer, which is composed of a water-soluble or water-dispersible resin (A) and an amino resin (B) with a triazine ring, is formed on at least one side of a base film, so that an easily-adhesive polyester film can be constituted in such a manner that the ratio of an absorbance of 1,540 cm<SP>-1</SP>to an absorbance of 1,340 cm<SP>-1</SP>is set at 0.010 or more by measurement using the ATR-IR method. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gas barrier package and a method for producing the same. More specifically, the present invention relates to a gas barrier packaging body having excellent barrier properties / deposited metal layer and excellent adhesion, and these properties do not deteriorate even after filling the contents.

  Polyester films are excellent in mechanical properties, heat resistance and transparency, and are widely used as industrial applications and food packaging films. However, the polyester film alone lacks so-called gas barrier properties such as oxygen and water vapor barrier properties, which is one of the extremely important performances for food packaging materials. Therefore, vapor deposition of metals such as aluminum or metal oxides on the film surface, or forming a so-called gas barrier layer, improves the gas barrier property and further enhances food storage stability.

  The polyester film has excellent properties, but its surface is highly oriented and crystallized, and the surface is highly cohesive and generally has low adhesion. For this reason, surface modification is achieved by physical treatment methods such as corona discharge treatment and plasma treatment, and chemical treatment methods that activate the surface of the film using chemicals such as acids and alkalis. Attempts have been made to increase However, with such a physical method, the process is simple, but the resulting adhesiveness is insufficient, and with the chemical method, the process becomes complicated and there are problems such as deterioration of the working environment.

  Apart from the physical and chemical treatment methods described above, there is a method of applying an undercoat having adhesive activity to a base film and laminating an easy-adhesion layer. This method is coated on the easy-adhesion layer. It is widely used because an easy-adhesive component can be selected according to various deposited layers.

  A water-based resin is widely used as a component of the easy-adhesion layer from the viewpoint of workability, safety, and cost, but polyurethane resin, polyester resin, acrylic resin, etc. are particularly suitable for improving adhesion to the deposited metal. Is done.

Moreover, various hardeners are mix | blended with the said water-based resin, and the performance as an easily bonding layer, especially water resistance and heat resistance are improved. Examples of the curing agent used for this purpose include isocyanate compounds, melamine compounds, and epoxy compounds (see, for example, Patent Documents 1 and 2). A method of obtaining an easily adhesive film using an isocyanate compound is described.
Japanese Patent Publication No.56-151562 Japanese Patent Publication No. 61-10311

  However, the easy-adhesion layer using these existing techniques has a problem that if the contents are filled after bag making, the adhesiveness is thereby lowered.

That is, various curing agents and cross-linking agents used as water-based easy-adhesion coating agents have a small amount of addition, and sufficient interlayer adhesion has not been obtained. It is often impossible to respond to.

By adding a substantially water-insoluble amino resin to an aqueous resin such as polyurethane or polyester resin as an easy-adhesion layer, an easily-adhesive plastic film excellent in heat resistance and water resistance can be obtained. Since it is insoluble, it is difficult to prepare a stable resin aqueous solution or aqueous dispersion.
On the other hand, a barrier film in which a water-dispersible resin and an amino resin having a triazine ring are provided as an easy-adhesion layer on a polyester film and an inorganic oxide layer is laminated on the easy-adhesion layer has been proposed. (For example, refer to Patent Document 3.)
Japanese Patent Laid-Open No. 2005-74879

  The present invention solves the above-mentioned problems, has excellent adhesion to the inorganic oxide layer, and thus has excellent gas barrier properties after vapor deposition, and deteriorates adhesion and gas barrier properties after filling the contents. An object of the present invention is to provide a plastic film and a package thereof.

That is, in the present invention, an easy-adhesion layer made of (A) a water-soluble or water-dispersible resin and (B) an amino resin having a triazine ring is formed on at least one surface of the base film, and the measurement is performed by the ATR-IR method. the ratio of the absorbance of the absorbance / 1340 cm ^-1 in 1540 cm ^-1 is a highly adhesive polyester film which is characterized in that 0.010 or more.

  The gas-barrier package of the present invention includes an easy-adhesion layer made of (A) a water-soluble or water-dispersible resin and (B) an amino resin containing a triazine ring on at least one surface of the base film. The easy-adhesion layer has excellent adhesion to the base film, and has sufficient strength to withstand the impact when the vapor deposition layer is laminated, and also has excellent adhesion to the vapor deposition layer. High barrier properties can be expressed.

  In addition, the gas barrier package of the present invention is obtained by adding (B) an amino resin having a triazine ring in an amount equal to or greater than (A) the water-soluble or water-dispersible resin component. The gas barrier property is excellent.

  As a result, peeling and floating of the vapor deposition layer from the base film due to the action of the contents after filling the bag is suppressed, cracking of the vapor deposition layer can be suppressed, and excellent adhesion and gas barrier properties can be expressed. Can be obtained.

  It is found that the aroma component such as mustard, wasabi, etc. is very small, but it acts on the vapor deposition layer and the easy-adhesion layer when passing through the package, and the adhesion at the interface decreases. This is because it has been found that due to the decrease in adhesiveness, the vapor deposition layer peels off from the substrate, floats, and the vapor deposition layer cracks, resulting in a decrease in barrier properties.

The feature can be expressed by a physical property that a ratio of absorbance at 1540 cm ⁻¹ / absorbance at 1340 cm ⁻¹ is 0.010 or more as measured by the ATR-IR method. When the absorbance ratio is less than 0.010, a package suitable for gas barrier packaging cannot be obtained due to the deterioration of the barrier effect.

  In the gas barrier property of the vapor deposition film, the adhesion between the vapor deposition layer and the substrate film is a key point. If the adhesion of the vapor deposition layer is weak, the gas permeates between the layers and the area through which the gas permeates is widened. Addition of an amino resin component having a triazine ring contributes to the improvement of adhesion. Measurement by the ATR-IR method makes it possible to accurately quantify the abundance of the cross-linking material component that improves the adhesion from a very thin easily adhesive layer.

The ratio of absorbance at 1540 cm ⁻¹ / absorbance at 1340 cm ⁻¹ as measured by the ATR-IR method is preferably 0.010 or more, particularly preferably 0.015 or more, and still more preferably 0.8, from the viewpoint of water vapor barrier properties. 020 or higher. In addition, when this absorbance increases, it means an increase in film thickness, which adversely affects the flexibility of the resulting polyester film. From this viewpoint, the ratio of absorbance at 1540 cm ⁻¹ / absorbance at 1340 cm ⁻¹ as measured by the ATR-IR method is preferably 0.2 or less.

  In addition, by providing the easy-adhesion layer, oligomer precipitation / aggregation from the base film during heating is also suppressed. As a result, defects due to foreign matter during vapor deposition are suppressed, and a higher level gas barrier film can be formed.

  In this case, it is preferable that the water-soluble or water-dispersible resin is at least one of a polyurethane resin, a polyester resin, an acrylic resin, and a polyvinyl alcohol resin.

  In this case, in each of the components (A) and (B) forming the easy-adhesion layer, the mass ratio of the component (A) to the component (B) is preferably 50/50 to 5/95. It is.

  Furthermore, in this case, the aqueous solution or aqueous dispersion is preferably applied to the base film before the end of biaxial orientation crystallization, dried, stretched in at least one direction, and then heat-treated. .

  ADVANTAGE OF THE INVENTION According to this invention, it can provide the plastic film and package which are excellent in adhesiveness and gas-barrier property, can prevent deterioration of the film characteristic by content filling, and can maintain performance.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  Examples of the water-soluble or water-dispersible resin applied to the structure of the easy-adhesion layer in the present invention include urethane resin, polyester resin, polyvinyl alcohol resin, and acrylic resin. Among them, urethane resin or polyester resin can be easily mixed, which is preferable in terms of barrier properties.

  Examples of the water-soluble or water-dispersible polyurethane resin applied to the structure of the easy-adhesion layer in the present invention include various polyurethane resins, polyurethane polyurea resins, and prepolymers thereof. Specific examples of such a urethane resin include diisocyanate components such as tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexyl diisocyanate, ethylene glycol, propylene glycol, and 1,4-butane. Diol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol, bisphenol, polyester diol, polyether diol, polycarbonate diol, reaction product with diol component such as polyethylene glycol, urethane prepolymer having an isocyanate group at the terminal , Amino compounds, aminosulfonates, polyhydroxycarbonates Bon acid, and reaction products of such bisulfite.

  Examples of the water-soluble or water-dispersible polyester resin include various polyester resins and modified products thereof. Specific examples of such polyester resins include terephthalic acid, phthalic acid, isophthalic acid, trimellitic acid, pyromellitic acid, 2-sulfoisophthalic acid, 5-sulfoisophthalic acid, adipic acid, sebacic acid, succinic acid, and dodecane. Reaction products of polyvalent carboxylic acid components such as diacid and diol components such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexanedimethanol and bisphenol In addition, modified products such as acrylic resins and epoxy resins are also included.

  For the easy-adhesion layer in the present invention, it is necessary to use an amino resin having a triazine ring. Examples of the amino resin include formaldehyde adducts such as melamine and benzoguanamine, and alkyl ether compounds based on alcohols having 1 to 6 carbon atoms. Specific examples include methoxylated methylol melamine, methoxylated methylol benzoguanamine, butoxylated methylol melamine, butoxylated methylol benzoguanamine, and the like, preferably methoxylated methylol melamine, butoxylated methylol melamine, and methoxylated methylol benzoguanamine, each alone Or it can be used in combination.

  In the easy-adhesion layer in the present invention, the composition ratio of (A) a water-soluble or water-dispersible resin and (B) an amino resin having a triazine ring needs to be A / B = 50/50 to 5/95 (mass ratio). And preferably 45/55 to 10/90, more preferably 45/50 to 15/85. By setting it within this range, water dispersibility can be ensured, adhesiveness between the base film and the deposited layer can be excellent, and excellent gas barrier properties can be exhibited. (B) If the blending ratio of the amino resin having a triazine ring with respect to the (A) water-soluble or water-dispersible resin is lower than 50% by mass, the adhesiveness cannot be lowered by the contents, and more than 95% by mass. However, there is no significant improvement in the adhesiveness obtained, and there is an adverse effect that the pot life of the blended solution is lowered.

  In the present invention, it is appropriate that the concentration of the aqueous solution or aqueous dispersion of the easy-adhesion layer applied to the film substrate is 1 to 30% by mass. More preferred is mass%.

  In addition, the aqueous solution or the aqueous dispersion and the base film can be blended with various additives such as an antistatic agent, an antioxidant and a lubricant as necessary, as long as the effects of the present invention are not impaired. is there.

Although the film base material in this invention is not specifically limited, When a polyester film is applied especially, the outstanding effect will be acquired. Examples of the polyester film include polyethylene terephthalate, polybutylene terephthalate, polyethylene 2,6-naphthalate and the like, and polyethylene terephthalate film (PET film) is most preferable. It is an excellent food packaging material with excellent mechanical properties, heat resistance and transparency.
The production of the polyethylene terephthalate film is not particularly limited, and a known method can be used, but the sequential biaxial stretching method is preferable from the viewpoint of film physical properties and production cost.
The film may be the same type or different type of laminated film. There are no particular limitations on the type of laminate, the number of laminations, the lamination method, and the like in the case of a laminated film, and any one of known methods can be selected according to the purpose.

  Although the polyester film thickness in this invention is not specifically limited, Generally, it is 5-250 micrometers, and when using for a package, it is desirable that it is 10-60 micrometers.

  As a method for coating the base film with the aqueous solution or aqueous dispersion of the easy-adhesion layer in the present invention, for example, the above aqueous solution or aqueous dispersion is applied to the base film before the end of biaxially oriented crystallization, that is, the unstretched or uniaxially stretched film. It can be applied to a so-called in-line coating method in which a biaxially stretched film is obtained through coating and heat treatment. The in-line coating method applies the above aqueous solution or aqueous dispersion to an unstretched or uniaxially stretched film, and then performs a stretching heat treatment. Therefore, it is possible to make the easy adhesion layer thinner than the post-coating method in which coating is performed after stretching. The adhesion between the base film and the vapor deposition layer can be improved. Moreover, since the application process of an easily bonding layer is integrated in the manufacturing process of a base film, manufacture of this easily bonding coat film is possible at low cost. In addition, regarding the extending | stretching method of a base film, a tenter type simultaneous biaxial stretching method and a sequential biaxial stretching method are applicable according to a material.

  In the present invention, the thickness of the easy-adhesion layer formed by applying and heat-treating an aqueous solution or aqueous dispersion is preferably 0.01 to 0.5 μm. If it is thinner than 0.01 μm, the adhesiveness is lowered, and if it is thicker than 0.5 μm, there is no significant change in easy-adhesion, etc. There are adverse effects such as damage to the easily adhesive layer during unwinding and film cutting, which is disadvantageous in terms of cost. As a method for applying the aqueous dispersion, any known method can be selected. For example, a bar coating method, an air knife coating method, a reverse roll coating method, or a gravure roll coating method can be applied. Among these, the bar coating method or the reverse roll coating method is preferable from the viewpoint of productivity and coating accuracy.

  The surface of the gas barrier package provided by the present invention is subjected to surface activation treatment such as corona treatment, printing, various functional coatings, laminating, etc. to add various performances and further improve the utility value. It is also possible to make it.

As a method for forming the inorganic oxide layer in the present invention, a physical vapor deposition method such as a vacuum vapor deposition method, a sputtering method or an ion plating method, or a CVD method (chemical vapor deposition method) is appropriately used.
The inorganic oxide is not particularly limited as long as it can be formed into a thin film such as silicon oxide, aluminum oxide, and magnesium oxide, but a multi-element inorganic oxide thin film containing silicon oxide and aluminum oxide is more effective. The multi-component inorganic oxide thin film containing silicon oxide and aluminum oxide here is a thin film formed from inorganic oxides by a known method, and the inorganic oxide is silicon oxide / aluminum oxide, There is no particular limitation as long as it is an inorganic oxide that can be thinned, such as magnesium oxide, but a preferred inorganic oxide is a multi-component inorganic oxide thin film containing aluminum oxide or silicon oxide, more preferably a silicon oxide / aluminum oxide binary inorganic oxide. It is a physical thin film.

  The heat sealable resin in the present invention is low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene vinyl acetate copolymer, polypropylene, ethylene / acrylic acid copolymer, ethylene / methacrylic acid. It is a film having heat-sealability formed of a copolymer, an ethylene / methyl acrylate copolymer, an ethylene / ethyl acrylate copolymer, an ethylene / methyl methacrylate copolymer, an ionomer or the like. Practically, a film made of low density polyethylene, ethylene vinyl acetate copolymer, linear low density polyethylene or polypropylene is often used as the heat sealable resin layer. The heat sealable resin layer generally has a thickness of about 3 to 100 μm, preferably about 5 to 70 μm.

  Further, as a method for forming the heat seal layer, it may be directly melt-extruded by an extrusion laminating method, or may be bonded by dry lamination or extrusion laminating using a sealant film formed in advance.

There is no restriction | limiting in particular as a bag making method, According to a use and the objective, it can select arbitrarily from a well-known method.
Although the bag form varies depending on the bag-making method, there is no limitation on this. In the case of filling and bag making with wasabi, mustard, etc., a four-sided seal with an automatic filling machine is preferable from the viewpoint of productivity.

  Hereinafter, the present invention will be described in detail by way of examples. The film properties obtained in each example were measured and evaluated by the following methods.

(1) measurement of absorbance 1540 cm ^-1 and 1340 cm ^-1 by ATR method Fourier transform infrared spectrophotometer (Perkin Elmer) was used to determine the absorbance by a solid ATR method. The crystal was an Se crystal, and both the background measurement and the sample measurement were performed after the inside of the data chamber was sufficiently replaced with nitrogen. Quantitation, in (1540 cm ^-1 as the baseline the line connecting the minimum value before and after the relevant peak as the baseline, around 1510, line connecting the minimum value in the vicinity of 1600 cm ^-1, 1340 cm-1 in 1310cm around ^-1 , A line connecting the minimum values in the vicinity of 1360 cm ⁻¹ ), and the peak height of the corresponding wavelength was read and calculated. In addition, the measurement was performed twice and the average value was calculated | required.

(2) Production of laminate film Obtained by an electron beam evaporation method using particulate SiO ₂ (purity 99.9%) and Al ₂ O ₃ (purity 99.9%) of about 3 mm to 5 mm as a deposition source. A mixed gas barrier layer of aluminum oxide and silicon dioxide was formed on the easy adhesion film. The vacuum layer contains an unwinding part, a coating part, and a winding part, and can be continuously deposited on the film. The pressure during vapor deposition was adjusted to 1.0 × 10 ⁻⁴ Torr. SiO ₂ and Al ₂ O ₃ were separated into two without mixing. An electron gun (hereinafter referred to as an EB gun) was used as a heating source, and two types of raw materials were heated in a time-sharing manner. At that time, the emission current of the EB gun was set to 1.2 A, and the heating ratio of SiO ₂ to Al ₂ O ₃ was heated at 1: 2. The film feed rate was 130 m / min, and a film having a thickness of 150 mm (angstrom) was formed. Moreover, the temperature of the roll for cooling the film at the time of vapor deposition was adjusted to -10 degreeC. Next, about 3 μm of polyurethane adhesive (TM-590 / CAT56 manufactured by Toyo Morton Co., Ltd.) was applied to the vapor deposition surface of the film, heat-treated at 80 ° C., and then a low density polyethylene film (L4102 thickness 40 μm manufactured by Toyobo Co., Ltd.). Was laminated at a nip pressure of 490 kPa on a metal roll heated to 80 ° C. to obtain a laminate film.

(3) Processing method for content resistance evaluation Create a heat-sealed bag on 3 sides, fill it with mustard and wasabi, heat-seal the mouth to make a 4-side sealed bag, and keep it at 40 ° C After 30 days storage in the environment.

(4) Measurement of gas barrier property The oxygen permeability of the package subjected to the above treatment was measured using an oxygen permeability measuring device (OX-TRAN100, manufactured by Modern Controls, measurement condition 23 ° C x 65% RH).

(5) Measurement of adhesiveness The package after the above treatment is cut into a strip of 15 mm width, and the T-type peel strength (N / 15 mm) is measured by a tensile tester (Toyo Seiki's Strograph V10-C). It was measured.

Example 1
78 parts by mass of an aqueous polyurethane resin (HW340, Dainippon Ink Co., Ltd., solid content 25%) is added to 22 parts by mass of an amino resin having a triazine ring (Cymel 370, manufactured by Mitsui Cytec Co., Ltd., solid content 88%). After stirring for 30 minutes, it was diluted with water and isopropanol to adjust the concentration so that the total solid content concentration was 5% by mass, and further stirred for 20 minutes to obtain an aqueous resin compounded liquid. A PET having an intrinsic viscosity of 0.62 (30 ° C., phenol / tetrachloroethane = 60/40) is pre-crystallized and then dried, and is extruded at 280 ° C. using an extruder having a T die, and a drum having a surface temperature of 40 ° C. It was rapidly cooled and solidified to obtain an amorphous sheet. The obtained sheet was stretched 4.0 times at 100 ° C. in the longitudinal direction between the heating roll and the cooling roll. On one side of the obtained uniaxially stretched film, the above-mentioned coating solution is applied by a fountain bar coating method so that the resin solid content thickness before stretching becomes 0.1 μm, and then it is guided to a tenter while drying and preheated at 100 ° C. The film was stretched 4.0 times at 120 ° C. and heat-treated at 225 ° C. while relaxing 6% in the transverse direction to obtain a biaxially stretched polyester film having a thickness of 12 μm. Table 1 shows the results obtained by subjecting the easy-adhesion layer-coated film to vapor deposition and measuring the adhesion and gas barrier properties.

(Examples 2 and 3)
Except having changed the compounding ratio of resin as shown in Table 1, the aqueous resin compounding liquid and the easily bonding layer coat film were obtained in the same procedure as Example 1. Table 1 shows the results of evaluating the aqueous resin compounding liquid and the results of measuring the film characteristics.

(Comparative Example 1)
Except not providing an easily bonding layer on a polyester base material, the biaxially-stretched polyester film and vapor deposition processing were performed in the same procedure as Example 1, and the film characteristic was evaluated.

(Comparative Examples 2 and 3)
Except having changed the compounding ratio of resin as shown in Table 1, the aqueous resin compounding liquid and the coating film were created in the same procedure as Example 1, and the aqueous resin compounding liquid and the film characteristic were evaluated.

  The gas barrier package of the present invention has good adhesion and gas barrier properties even after filling with contents such as wasabi and mustard, so it can be used for a wide range of packaging materials and contribute to the industry. It ’s big.

Claims (4)

An easy-adhesion layer made of (A) a water-soluble or water-dispersible resin and (B) an amino resin having a triazine ring is formed on at least one side of the base film, and the absorbance / of 1540 cm ⁻¹ as measured by the ATR-IR method. A gas barrier packaging body, which is a polyester film having an absorbance ratio of 1340 cm ⁻¹ of 0.010 or more, and a gas barrier layer made of an inorganic oxide and a heat seal resin layer are sequentially laminated on the easily adhesive layer.   The gas barrier packaging body according to claim 1, wherein the water-soluble or water-dispersible resin is at least one of a polyurethane resin, a polyester resin, an acrylic resin, and a polyvinyl alcohol resin.   It is a gas-barrier packaging body of Claim 1, Comprising: In each said component (A) and (B) which forms the said easily bonding layer, mass ratio of a component (A) and a component (B) is 50 / 50-5. / 95 A gas-barrier package characterized by the above-mentioned.   The gas barrier packaging body according to claim 1, wherein the aqueous solution or the aqueous dispersion is applied to a base film before completion of biaxial orientation crystallization, dried, stretched in at least one direction, and then heat-treated. A method for producing a gas barrier packaging product.