JPS6134391B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to coated films. Specifically, the present invention relates to a coated film that is excellent in suitability for high-speed packaging in packaging machines, has excellent oxygen gas and water vapor barrier properties, and has excellent transparency. Films such as regenerated cellulose, biaxially oriented polypropylene, and polyester have completely insufficient heat-sealability by themselves, and when used for overlap packaging, etc., vinyl chloride copolymer resin, chloride copolymer resin, etc. Vinylidene copolymer resin, chlorinated polypropylene resin,
A method has been proposed in which a coating liquid mainly composed of ethylene copolymer resin, acrylic copolymer resin, etc. is coated to impart heat sealability at low temperatures. Among them, vinylidene chloride copolymer resins have excellent oxygen gas and water vapor barrier properties and are advantageous in terms of food protection performance. Good slipperiness of the coated surface is essential for the performance required for suitability for high-speed packaging in packaging machines. However, in order to improve slipperiness, it is common practice to roughen the coating surface by adding fine powders such as kaolin, silica, calcium carbonate, and bentonite, but the amount of these inorganic lubricants added There is a limit due to the transparency of the coated film, and it has been difficult to obtain good slipperiness while maintaining transparency. As a result of various studies, the inventors of the present invention discovered a coated film that has excellent transparency, suitability for high-speed packaging, and even superior performance, leading to the present invention. That is, the present invention combines 0.05 to 1.0 parts by weight of a lubricant mixture consisting of 5 to 70% by weight of an inorganic lubricant and 30 to 95% by weight of an organic lubricant with a softening temperature of 100°C or higher, and 0.5 to 5.0 parts by weight of a wax emulsion (solid content). The present invention relates to a coated film characterized in that it is coated with a liquid obtained by adding 100 parts by weight of an emulsion (in terms of solid content, the same applies hereinafter) mainly composed of a thermofusible polymer resin. In order to obtain good slipperiness, fine powder having a softening temperature higher than that of the coating film is uniformly dispersed and protrudes from the coating surface, and it is preferable that the number thereof is as large as possible. Therefore, it is effective in reducing the damage to transparency of organic lubricants having a refractive index close to that of the coating film. Moreover, as shown in FIG. 1, better slipperiness and transparency can be obtained by mixing organic lubricants or inorganic lubricants than by using them alone. In the present invention, inorganic lubricant 6 to 70
Weight% preferably 5-45% and organic lubricant 30-45% by weight
By mixing and using 95% by weight, preferably 55 to 95% by weight, good slipperiness and transparency can be obtained. As the organic lubricant, fine powders of polyethylene, polypropylene, polyvinyl chloride, polystyrene, etc. with a wax temperature of 100°C or higher can be used. The softening temperature of the organic lubricant is preferably 100° C. or higher in view of suitability for packaging machines, that is, in order to maintain good slipperiness even when in contact with a hot plate for thermally bonding films in a packaging machine. If the softening temperature is lower than 100°C, when the coated film comes into contact with the hot plate of the packaging machine, the organic lubricant protruding from the coated surface loses its original spherical shape, which may have an adverse effect on slipperiness. Examples of inorganic lubricants include the above-mentioned kaolin, silica, calcium carbonate,
Bentonite-based fine powder can be used. Both inorganic and organic lubricants have an average particle size of 1.
-15μ can be used, but 2-7μ is preferable. In order to obtain good slip properties, it is necessary that the average particle size be larger than the thickness of the coating film. Emulsions based on hot-melt polymer resins include vinyl chloride copolymer resins, vinylidene chloride copolymer resins, chlorinated polypropylene resins, ethylene copolymer resins, acrylic copolymer resins, etc. Although emulsions of known resins can be used, emulsions of vinylidene chloride copolymer resins are particularly preferred because they melt at temperatures below 100°C and can provide barrier properties against oxygen gas and water vapor. As the wax emulsion, emulsions of known waxes such as paraffin wax, carnauba wax, montan wax, and fatty acid amide can be used. Wax emulsion is added to assist slipperiness and prevent adhesion of the coating film.The smaller the wax emulsion particles, the better the effect in terms of uniform dispersion in the coating film. be. If the particles are large, there will be an adverse effect such as making the appearance of the coated film whitish. A particularly preferred material for the substrate film is a stretched polypropylene film, which has a high degree of transparency, a high degree of mechanical properties, a high degree of packaging suitability, and is inexpensive. There are known methods in which the surface of the film is subjected to various treatments to improve adhesion during coating. In the present invention, it is extremely effective to apply an adhesion improver to the coating layer in advance after performing these methods, ie, corona discharge, high frequency, flame, and chromium mixture treatment. It goes without saying that the film may be coated on both sides or on one side in the present invention, and the coating device may be a dip coater, roll coater, gravure coater, air knife coater, etc. depending on the purpose.
A Meyer bar coater or the like can be used. Furthermore, as is known in the art, additives such as antioxidants, antistatic agents, and ultraviolet stabilizers can be added to the coating solution. The thickness of the coating layer is suitably 1 to 10 .mu.m, particularly preferably 2 to 5 .mu.m. The covering film of the present invention can be used as it is for packaging, or can be used after being made into a bag. It can also be laminated and used as a packaging material. More specifically, this film can be used for snack foods such as kutsky, kratska, potato chips, fatty foods such as chiyokolate and castella, as well as rice crackers, seaweed, furikake, peanuts, tobacco, shredded tobacco, coffee, handkerchiefs, gauze, textiles, and soap. It is particularly suitable for packaging detergents, dry batteries, unprocessed mechanical parts, etc. Next, examples of the present invention will be shown, but it goes without saying that these examples are for explaining the present invention and are not intended to limit the present invention. The properties of the coated film in this example were tested in the following manner. Blocking property: 0.5Kg/cm 2 at 40℃ by sandwiching several sheets of 100mm x 100mm film between two glass plates ^.
After being left for 8 hours under a load of 1, the mixture was allowed to cool to room temperature.
The degree of blocking of the film was ranked as follows. The film separates into individual sheets without applying any Γ force. ......Excellent ΓIf you apply a little force, it will separate into sheets. ......Good When Γ force is applied, it separates into sheets, but the coated resin partially peels off. ...... Impossible water vapor permeability: Measured under the conditions of 40°C and 90% RH using a cup specified in JIS Z-0208. Oxygen gas permeability: Gas chromatography method (measuring device Lyssy
Gas Permeability Testing Apparatus L-
66), measurements were made at 20°C using oxygen gas at 0% humidity and helium gas as a compensation gas. Haze degree: Measured using a direct reading haze computer model HGM 2D manufactured by Suga Test Instruments Co., Ltd. using four coated films stacked one on top of the other. Slip property: Measured by a method according to ASTM D 1894-63 to determine the static friction coefficient and dynamic friction coefficient. Examples 1 to 5 and Comparative Examples 1 to 3 After corona treatment was performed on both sides of a biaxially stretched polypropylene film (thickness: 20μ) to make the contact angle of water on the treated surface 75°, first one side was subjected to gravure treatment. An undercoat liquid was applied using a coater and dried.
The uncoated surface was coated with the liquid of the formulation (a) using a Meyer bar coating machine with the lubricant composition shown in Table 1, and dried at 110°C for 15 seconds. Thereafter, the undercoat solution and (a) prescription solution were sequentially coated on the opposite side of the coated surface in exactly the same manner. The coated film obtained as described above was subjected to property tests and the results are shown in Table 1. In addition, this covering film was used to overwrap small boxes (77 x 57 x 22 mm: cardboard boxes) using a W-323 type overwrap packaging machine manufactured by Tokyo Jidoki Co., Ltd. (packing speed: 300 pieces/min). ) to determine the incidence of packaging defects. The results are also shown.
Shown in 1. The results of the slip properties of the above property tests are shown in FIG. 1 as a graph showing the relationship between the lubricant mixing ratio and the slip properties.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the lubricant mixing ratio and the slipperiness of the coated film.

Claims (1)

[Claims] 1. A lubricant mixture consisting of 5 to 70% by weight of an inorganic lubricant and 30 to 95% by weight of an organic lubricant with a softening temperature of 100°C or higher.
0.05-1.0 parts by weight and wax emulsion 0.5-5.0
1. A coated film having good suitability for packaging machines, characterized in that it is coated with a liquid obtained by adding 100 parts by weight (as solid content) of an emulsion mainly composed of a heat-melting polymer resin.