JP2700406B2 - Gas barrier film - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a gas barrier film. More specifically, a film having excellent blocking resistance, transparency, printability, water vapor barrier property, and gas barrier property, and further having excellent hot water resistance of a heat-sealed portion after heat-sealing a composite film using the gas-barrier film. About.

(Prior Art) Paper, cellophane, metal foil, plastic film, plastic bottles and the like are coated with a vinylidene chloride copolymer resin to impart gas barrier properties, water vapor barrier properties, and heat sealing properties. ing. Among them, polyethylene film, polypropylene film,
BACKGROUND ART Plastic films such as polyester films, polyamide films, polyvinyl alcohol films, and polyvinyl chloride films, and transparent films such as cellophane (regenerated cellulose film) are coated with a vinylidene chloride-based copolymer resin and are often used for packaging.

When coating a vinylidene chloride copolymer resin on a transparent film, in order to improve blocking resistance and slipperiness,
Inorganic fillers, especially porous silica fine particles, are blended with the vinylidene chloride copolymer.

When wrapping foods with these films, the contents may be boiled or retorted to sterilize or cook the contents by bagging the films, filling the foods, and then immersing in hot water. In the case of boiling or retorting, a composite film obtained by laminating a vinylidene chloride copolymer resin-coated surface and another film is generally used. There are two main methods for packaging food. In other words, there are a method of filling a premade bag with food and sealing it with a heat sealer, and a method of filling and sealing food while making a bag with a manufacturing bag filling machine having a heat seal bar. The food thus filled and sealed is quickly boiled or retorted in order to maintain its quality.

(Problems to be Solved by the Invention) However, a composite film which is formed by coating a transparent film with a vinylidene chloride-based copolymer resin mixed with porous silica fine particles and laminating the coated surface with another film is used. If a bag is formed, filled with food, and sealed with a heat sealer, and then subjected to a boil or retort treatment, there is a problem that the heat seal portion is whitened and the hot water resistance is poor.

(Means for Solving the Problems) The present inventors have conducted intensive studies to solve the above problems, and as a result, by adding and blending specific fine particles at a specific ratio to the vinylidene chloride-based copolymer resin, It has been found that the above problem can be solved, and the present invention has been achieved.

That is, the present invention provides a vinylidene chloride-based copolymer resin 10
In 0 parts by weight, the following formula is satisfied: 0 ≦ D + (σ / 2) −t ≦ tt: coating layer thickness (μm) D: average particle diameter (μm) σ: standard deviation of particle diameter (μm) A gas barrier film having a coating layer containing 0.02 to 1.0 parts by weight of inorganic fine particles that are substantially true spheres and have no voids in the particles.

The substrate film applied to the present invention only needs to be transparent,
For example, cellulose ester films such as cellophane (regenerated cellulose film) and acetate films, vinyl chloride films, polyethylene films, polypropylene films, polystyrene films, polyester films such as poly-4methyl-1-pentene films, polyethylene terephthalate films, Examples thereof include transparent films such as polyamide-based films such as polyhexamethylene adipamide films, polyvinyl alcohol films, saponified ethylene-vinyl acetate copolymer films, polyacrylonitrile films, and fluorine-based resin films such as vinylidene fluoride. However, the present invention is not limited to these.

These transparent films may be subjected to a physical or chemical surface treatment such as a corona discharge treatment, a low-temperature plasma treatment, a flame treatment, and a chromic acid mixed liquid treatment for the purpose of improving the wettability and the adhesion as required. Furthermore, an undercoat agent such as an organic solvent solution, an aqueous solution, and an aqueous dispersion may be applied.

The vinylidene chloride copolymer resin, which is the main component of the coating layer of the present invention, preferably has a vinylidene chloride content of 85 to 95% by weight. If it is less than 85%, the gas barrier property, the water vapor barrier property, the solvent resistance, and the hot water resistance of the heat seal portion of the composite film are inferior. If it exceeds 95% by weight, the solubility, film formability, flexibility, ink adhesion and the like are insufficient. The monomer used for the copolymerization may be any monomer that can be copolymerized with vinylidene chloride, and can be selected according to its use. For example, vinyl chloride, styrene, acrylonitrile, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, maleic anhydride, acrylic acid alkyl esters, methacrylic acid alkyl esters, fatty acid vinyl esters, alkyl vinyl ethers , Chrysidyl methacrylate, hydroxyethyl methacrylate,
Examples include, but are not limited to, styrene sulfonic acid and metal salts thereof.

Formula: 0 ≦ D + (σ / 2) −t ≦ tt: coating layer thickness (μm) D: average particle diameter (μm) for the purpose of preventing blocking and imparting slipperiness to the vinylidene chloride copolymer resin [sigma]: A substantially spherical inorganic fine particle which does not have a void in the particle, which satisfies the standard deviation (μm) of the particle diameter, is added and blended. Substantially spherical fine particles are those having a minor axis / major axis of 0.90 in an electron micrograph of the particles.
The primary particles described above are referred to as simply spherical particles.

When the average particle diameter D is 0> D + (σ / 2) −t, the coating layer is poor in blocking resistance and slipping property because part of the particles hardly appear on the surface of the coating layer. When D + (σ / 2) -t> t, the particle diameter is too large as compared with the thickness of the coating layer, so that when printing, ink is liable to occur and printing suitability is poor.

If there are voids in the particles, the surface area increases, and the coating layer has an air layer having a refractive index significantly different from that of the fine particles, and the vinylidene chloride-based copolymer resin-air layer interface and the fine particles-air layer Transparency is greatly reduced due to scattering of visible light at the interface. Furthermore, at the time of boiling treatment (immersion in hot water)
In particular, immediately after extrusion coating polyethylene resin etc. on the coating surface of the vinylidene chloride copolymer resin composition, or extrusion coating of polyethylene resin etc. on the coating surface of the vinylidene chloride copolymer resin compound, or dry laminating the polyethylene film etc. Even after heating and aging sufficiently, heat-sealing film surfaces such as polyethylene are superposed on each other and heat-treated after boil or retort treatment. .

Non-spherical fine particles generally have a minor axis in the thickness direction of the coating layer, and have the same particle diameter (volume average value) as compared to true fine particles, and have smaller protrusions than the coating layer. Therefore, blocking resistance is inferior. In such a case, it is necessary to increase the addition ratio in order to satisfy the blocking resistance, and as a result, the transparency, gas barrier property, water vapor barrier property and printability are adversely affected, and the object of the present invention is satisfied. do not do.

Fine particles to be added to and blended with the vinylidene chloride-based copolymer resin satisfy the formula: 0 ≦ D + (σ + 2) −t ≦ t and are spherical inorganic fine particles having no voids in the particles. -Heat resistance is required to maintain the shape of a true sphere in the drying process.

The addition ratio of the true spherical fine particles is preferably from 0.02 to 1.0 part by weight based on 100 parts by weight of the vinylidene chloride copolymer resin. 0.
If it is less than 02 parts by weight, the number of particles partially exposed on the surface of the coating layer is too small, blocking resistance, slipperiness is poor, and 1.
If the amount exceeds 0 parts by weight, the number of particles is too large, which adversely affects transparency and printability.

The vinylidene chloride-based copolymer resin has, in addition to the spherical fine particles having no voids, if necessary, waxes, an antistatic agent, an ultraviolet absorber, an oxidizing agent as long as the object of the present invention is not impaired. For prevention, a colorant, a crosslinking agent, and the like may be blended.

The coating layer of the vinylidene chloride-based copolymer resin compound is coated with an aqueous dispersion of the vinylidene chloride-based copolymer resin by dispersing and dissolving true spherical fine particles having no voids, and other additives as necessary, and then coating and drying. Can be formed. It is more preferable that the spherical fine particles are added to the aqueous dispersion of vinylidene chloride-based copolymer resin after preparing the dispersion in advance from the viewpoint of dispersion efficiency.

For the application of the aqueous dispersion coating composition of the vinylidene chloride resin composition prepared as described above, for example, a Meyer bar coater, a gravure roll coater, a kiss coater, a reverse roll coater, an air knife coater, a dip coater, a squeeze coater, and the like. Various coaters can be used and are not particularly limited.

Various dryers such as a hot air dryer, an infrared dryer, and a microwave dryer can be used for drying the applied coating agent, and are not particularly limited.

The thickness of the coating layer is usually from 1.0 to 10 μm, and more preferably from 2 to 5 μm, due to restrictions on its function, cost and productivity.

Next, the transparent film on which the coating layer of the vinylidene chloride-based copolymer resin composition has been formed is usually wound into a roll. The vinylidene chloride copolymer resin immediately after coating has a low degree of crystallinity, and in order to further improve the gas barrier property, steam barrier property, hot water resistance, and solvent resistance of the resin,
Heat aging is more preferable. Aging temperature is 35-60 ℃
Is preferred. When the temperature is lower than 35 ° C., aging takes a long time.
If it exceeds 60 ° C., the deformation of the film becomes remarkable, which is not preferable in terms of the quality of the film.

(Effect of the Invention) The vinylidene chloride-based copolymer resin compound-coated film of the present invention is used for coating a vinylidene chloride-based copolymer resin coating layer with:
The formula satisfies the formula: 0 ≦ D + (σ / 2) −t ≦ t, and contains 0.02 to 1.0 parts by weight of spherical inorganic fine particles having substantially no voids in the particles, so that transparency is impaired. It has excellent blocking resistance, excellent slipping properties, excellent gas barrier properties, water vapor barrier properties, and printability, and a composite film using the film with excellent hot water resistance.

(Examples) Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. The evaluation methods and measurement methods used in the examples are as follows.

1) Average particle size and standard deviation Volume average particle size and its standard deviation measured by Coulter Counter TA-II manufactured by Nikkaki Co., Ltd.

2) Blocking resistance Immediately after coating, an unripened coated product was sampled to a size of 50 mm x 60 mm, and the coated noodle-non-coated surface was superimposed.
270 g / cm ² with 8.1 kg weight at 40 ° C
Was applied for 24 hours, allowed to cool to room temperature, and evaluated according to the following criteria.

Grade 1: The film is divided into individual sheets without applying force.

Grade 2: If you apply a little force, it will be separated one by one.

Grade 3: You can't separate unless you pinch it with your fingers.

Grade 4: Grain is separated by pinching with both hands, but the coating layer is partially peeled off.

Grade 5: Adhesion is severe and does not separate at all.

3) Slip property Dynamic friction coefficient between the coated surface and the uncoated surface according to ASTM D1894.

4) Transparency Haze according to JIS K6714.

5) Oxygen permeability According to ASTM D3984. 20 ° C x 100% RH.

6) Moisture permeability According to JIS Z0208. 40 ° C x 90% RH.

7) Printability Using Lamic F220 716 red manufactured by Dainichi Seika Kogyo Co., Ltd. adjusted to a viscosity of 20 seconds with Zahn Cup # 3, 175 lines 5 μm, 15 μm, 22 μm, 36 μm made by conventional method
The coated surface was printed with a gravure cylinder having a depth of m, and the degree of ink loss (pinhole) was evaluated as follows.

Grade 1: There is no ink dropout (pinhole).

Grade 2: There is some ink missing in the 5 μm area.

Grade 3: There is some ink missing in the 15 μm area.

Grade 4: Part of the ink was partially missing at 22 μm.

Fifth grade: Some ink is missing at 36 μm.

8) Boil resistance The coated surface and the L-LDPE film "EL ACE" H type 40 μm manufactured by Kojin Co., Ltd. were applied to a dry lamination adhesive manufactured by Dainichi Seika Kogyo Co., Ltd. Seikabond E-285 / C-75N (coating amount 3.0 g
/ m ² ), and aged by heating at 40 ° C. for 2 days. L-LDPE face to face, 180 ° C, seal face pressure 1
Immediately after heat sealing with Kg / cm ² and a sealing time of 1 second, it was immersed in boiling water for 30 minutes. After the immersion treatment, the humidity was controlled at 20 ° C. and 65% RH for 24 hours, and the haze of the heat-sealed portion was measured. For comparison, the haze of a sample not immersed in boiling water was also measured.

9) Retort resistance Coated surface and Toray Industries' CPP film "Trefane NO" 39
61, 60 μm was manufactured by Dainichi Seika Kogyo Co., Ltd. for dry lamination adhesive Seikabond E-285 / C-75N (coating amount 4.0 g / m ² )
And then heat-aged at 40 ° C. for 3 days. CPP
Immediately after heat-sealing at 190 ° C, sealing surface pressure of 1 kg / cm ² and sealing time of 1 second, they were immersed in hot water at 120 ° C for 30 minutes with a retort sterilizer manufactured by Hisaka Manufacturing Co., Ltd.
It was quenched with cold water to room temperature. After immersion, 24 hours at 20 ℃ 65% RH
After humidity control for a time, the haze of the heat-sealed portion was measured.
For comparison, the haze of a sample not immersed in hot water was also measured.

Example 1, Comparative Examples 1-2, Reference Examples 1-7 Biaxially stretched 6 nylon film Boneal manufactured by Kojin Co., Ltd.
A 15 μm corona-treated surface was coated with an adhesive Adcoat 502 (a curing agent Cat-10) manufactured by Toyo Morton Co., Ltd., diluted with ethyl acetate and dried. The coating amount is 0.4g / m ²
Met. Fine particles shown in Table 1 were added to Sarantex L-511, an aqueous dispersion of vinylidene chloride copolymer resin manufactured by Asahi Kasei Corporation, and dried and coated at 3 μm or 2 μm at 120 ° C. Dried for seconds. The addition ratio of the fine particles is a percentage by weight based on the solid content of L-511.

The blocking resistance was evaluated on the sample immediately after coating, and the rest was
Aged at 50 ° C. for 48 hours and used for other evaluations. The results are shown in Table 1.

Example 1 according to the present invention was a film having excellent blocking resistance, slip properties, transparency, oxygen barrier properties, water vapor barrier properties, printability, and hot water resistance. Comparative Examples 1 to
No. 2 has at least one or more defects in these properties. Since Comparative Examples 1 and 2 use porous fine particles,
After boiled and retorted, it became white.

Claims (2)

(57) [Claims] 1. Formula: 0 ≦ D + (σ / 2) −t ≦ tt: coating layer thickness (μm) D: average particle diameter (μm) σ in 100 parts by weight of vinylidene chloride-based copolymer resin : Gas having a coating layer containing 0.02 to 1.0 parts by weight of inorganic fine particles that are substantially spherical and satisfy the standard deviation (μm) of the particle diameter and have no voids in the particles. Barrier film. 2. The gas barrier film according to claim 1, wherein the base film is a polyamide-based film.