JPS6136784B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a vinylidene chloride resin emulsion coated film. For more information, see Transparency.
This invention relates to a method for producing a vinylidene chloride resin emulsion coated film with excellent slip properties, anti-blocking properties, and barrier properties. Regenerated cellulose film, biaxially oriented polypropylene film, biaxially oriented polyethylene terephthalate film, etc. are coated with a liquid mainly consisting of vinyl chloride copolymer resin, vinylidene chloride copolymer resin solution, or emulsion to provide thermal adhesive properties. It is widely practiced to impart oxygen gas and water vapor barrier properties. Particularly, the method of coating the emulsion liquid is preferable in terms of liquid storage and safety, but on the other hand, the surfactant contained in the emulsion is also present on the coated surface, and after coating and drying, it is exposed to air. If the coated film is wound up into a roll with moisture trapped in it, there is a problem in that the slipperiness, transparency, and anti-blocking properties of the coated film deteriorate significantly. In addition, it has long been known that heat treatment after coating with a vinylidene chloride copolymer resin emulsion promotes crystallization of the coating film and improves oxygen gas and water vapor barrier properties.
For example, in Japanese Patent Publication No. 54-1756, vinylidene chloride
At least one side of the film is coated with an aqueous emulsion of vinylidene chloride polymer containing 85 mol% or more, dried, and then wound into a roll. The above methods of thermal formation have been proposed, but
When the coated film is rolled up into a roll after absorbing moisture from the air and left to age in an atmosphere of 35 to 60°C, the coated film is completely and uniformly rolled up as shown in Figure 1. If not, the pressure applied to the film coating differs between the concave and convex parts of part a in Figure 1, which may cause some of the bleeding (precipitation) of surfactants, additives, etc. contained in the coating film onto the coating surface. arise. In addition, in the subsequent heat treatment, the difference in the amount of bleeding becomes even larger, and the covering film becomes like a striped pattern, the transparency is partially unevenly lost, and the sliding property and anti-blocking property are significantly deteriorated. be. The present inventors have conducted various studies to solve these drawbacks, and as a result, have arrived at the present invention. That is, in the present invention, at least one surface of a film is coated with a coating liquid mainly composed of a vinylidene chloride copolymer resin emulsion, dried, cooled to 5 to 30°C, and then heated as it is for 5 to 30°C.
The film roll is rolled up at 30℃ and 35~70% RH, and left at room temperature for 6 hours or more.
Transparency, slipperiness, blocking resistance, characterized by heat treatment for 6 hours or more in an atmosphere of
This is a method for producing a coated film with excellent barrier properties. More specifically, after a film is coated with a coating liquid mainly composed of a vinylidene chloride resin emulsion, the coated layer is dried by heating in a drying zone at 80 to 120°C for 5 to 30 seconds. The dried coated film is heated, for example, by cooling rolls to a temperature of 5 to 30
After cooling to ℃, it is wound into a roll. At this time, in order to wind the film without absorbing moisture in the air, it is necessary to control the atmosphere from the cooling roll to the winder section at 5 to 30℃ and 35 to 70%RH, especially at 16 to 20℃. It is preferable to control the temperature and humidity at 40-55% RH. The above-mentioned cooling roll preferably has a chrome-plated roll surface from the viewpoint of cooling efficiency, but it is needless to say that the roll is not limited to a chrome-plated roll. It is desirable to blow air from the cooling roll onto the coated film in a temperature- and humidity-controlled area of the winder section, the temperature being lower than the moisture content of the atmosphere in the area, in order to further exhibit the effects of the present invention. After the covering film is rolled up into a roll,
It is preferably wrapped in a polypropylene film, moisture-proof coated cellophane, moisture-proof coated glassine, etc. in an atmosphere of ~30℃ and 35~70% RH, left in a room temperature atmosphere for 6 hours or more, and then wound onto another core. . Next, heat treatment is performed in an atmosphere of 35°C to 55°C. It is preferable that the time of leaving it in the room temperature atmosphere is 6 hours or more, and if it is less than 6 hours, the temperature of the coated film will not return to room temperature when the coated film is wound up into a roll, and moisture in the air will be removed due to the difference in temperature and humidity. This is because they may adhere to the covering film. Before heat treatment, the covering film is re-wound or slit and wound onto another core.By re-winding the uneven winding as shown in Fig. 1, it becomes a roll winding with almost no unevenness. This is to do so. At the time of rewinding, the covering film may be simply wound around another core, or may be wound while being slit to an arbitrary width. The heat treatment conditions are a treatment temperature of 35 to 55℃.
However, it is preferably 40 to 50°C. The higher the temperature, the more effective it is for oxygen gas and water vapor barrier properties.
If the temperature exceeds 55°C, the temperature approaches the thermal adhesion temperature between the coatings, which is undesirable as it tends to block. Further, a temperature lower than 35°C is not preferable because the heat treatment requires a long time. The treatment time is 6 hours or more, preferably 12 to 96 hours. Particularly, the portion of the film wound into a roll near the core requires the longest time for heat to be transmitted, and if it is less than 6 hours, the heat treatment effect will be insufficient. Films used in the present invention include stretched or unstretched films of polyethylene, polypropylene, poly-4-methylpentene-1, polyethylene terephthalate, polyethylene terephthalate/isophthalate, nylon 6, nylon 66, nylon 12, regenerated cellulose, etc. However, those made of thermoplastic resin are preferably biaxially stretched, and biaxially stretched polypropylene film is particularly good. During coating, methods are known in which various treatments are applied to the surface of polyolefin film in order to improve adhesion. The present invention also uses these methods,
That is, corona discharge, high frequency, fire, chromium mixture treatment, etc. are possible. In addition, vinylidene chloride-based copolymer resin emulsions include vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer, vinylidene chloride-acrylic acid ester copolymer, vinylidene chloride-methacrylic acid ester copolymer, and These copolymers include copolymers in which unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, and unsaturated dicarboxylic acids are copolymerized as third and fourth components. The content of vinylidene chloride in the vinylidene chloride copolymer is not particularly limited, but is preferably 85% or more from the viewpoint of water vapor and oxygen gas barrier properties. Furthermore, vinylidene chloride homopolymer is unstable and is not practical. Additives such as lubricants, antistatic agents, waxes, dyes, stabilizers, and plasticizers may be used in the vinylidene chloride copolymer resin emulsion. The coated film produced by the method of the present invention can be used as is, either as an external package or as a bag. It can also be used as a similar packaging material after being laminated. More specifically, the coated film of the present invention can be used to coat snack foods such as kutsky, kratski, potato chips, etc., fatty foods such as chiyocolate, castella, etc.
It is also suitable for packaging rice crackers, seaweed, furikake, peanuts, tobacco, shredded tobacco, coffee, handkerchiefs, gauze, textiles, soap, detergents, dry batteries, untreated mechanical parts, etc. Next, examples of the present invention will be shown, but it goes without saying that these are for illustrating the present invention and are not intended to limit the present invention. The properties of the coated polyolefin film in the present invention were measured by the following method. (a) Slip property The coefficient of friction between the coated surfaces of the coated film is
Measured according to ASTM D 1894-63. (2) Blocking resistance The blocking resistance of the film was observed when the film was wound onto a roll after being coated and when it was re-wound onto a roll, and when the film was re-wound after being heat-treated. The results were shown. (3) Transparency Ranking was done by visual judgment as follows. Almost equivalent to biaxially oriented polypropylene film
…………Excellent, slightly inferior to biaxially oriented polypropylene
…Good: Fairly inferior to biaxially oriented polypropylene, but better than low-density polyethylene … Fair: Equal to or lower than low-density polyethylene
…………Not possible (4) Oxygen gas permeability Gas chromatography method (measuring device Lyssy Gas
Permeability Testing Apparatus L-66) was measured at 20°C using oxygen gas with a humidity of 0% and helium gas as a compensation gas. Example 1 Prescription (A) solution was coated on the coated surface of a 20 μm thick biaxially stretched polypropylene film coated with an undercoat by the Mayer bar method in a coating amount of 8 g/m ² . After coating, it was dried at 105°C for 20 seconds, passed through a cooling roll whose surface temperature was 19°C, and rolled up on a roll in an atmosphere of 19°C and 45% RH. Wrap this film in polypropylene film while it is still wound, and store it in an atmosphere of 25°C for 24 hours.
After leaving it for a while, it was wound onto another roll and placed in a 40°C atmosphere and heat-treated for 2 days. Table 1 shows the results and the properties of the coated film obtained. Prescription (A)... Vinylidene chloride/acrylic acid ester copolymer (copolymerization ratio 90/10) emulsion......100 parts by weight Inorganic lubricant (silica powder, particle size: 3.0
μ) …………0.1 Comparative Example 1 In the same manner as in Example 1, the anchor-coated surface of a biaxially stretched polypropylene film was coated with solution (A), dried, and then air-cooled at 24°C and 73% RH. , rolled up into a roll. Then change to another roll,
Heat treatment was performed for 2 days in an atmosphere of 40°C. Table 1 shows the properties of the obtained coated film. Comparative Example 2 In the same manner as in Example 1, the anchor-coated surface of a biaxially stretched polypropylene film was coated with liquid formulation (A), dried, cooled in air at 24°C and 68% RH, wound onto a roll, and left as is. Heat treatment was performed in an atmosphere of 40°C for 2 days. Table 1 shows the properties of the obtained coated film. Comparative Example 3 In the same manner as in Example 1, the anchor-coated surface of a biaxially stretched polypropylene film was coated with liquid formulation (A), and after drying, the coated film was heated to a surface temperature of 19°C.
Pass through a chill roll at 19℃, 45%
It was wound into a roll under a RH atmosphere. The coated film was wrapped in a polypropylene film while being wound, and after being left in an atmosphere at 24° C. for 24 hours, it was re-wound onto another roll. Table 1 shows the properties of the obtained coated film.

[Table] Example 2 The coated surface of a 20 μm thick biaxially stretched polypropylene film coated with an undercoat was coated with solution (B) by the Mayer bar method in a coating amount of 2.3 g/m ² . After coating, it was dried at 110°C for 20 seconds. Then, the opposite side was coated in exactly the same manner and dried. After drying, it was passed through a chill roll with a surface temperature of 20°C and wound up on a roll in an atmosphere of 20°C and 40% RH. The product was wrapped in a polypropylene film as it was, left in an atmosphere at 24°C for 6 hours, then wound onto another roll, placed in an atmosphere at 40°C, and heat-treated for 3 days. The results and properties of the obtained film are shown in Table 2. Prescription (B)... Vinylidene chloride/acrylonitrile copolymer (copolymerization ratio: 85/15) emulsion......100 parts by weight wax emulsion (mp.78℃)
…………1.0 Inorganic lubricant (silica powder, particle size: 3μ)
…0.1 Comparative Example 4 A polypropylene film was coated with formulation (B) in the same manner as in Example 2, dried, air cooled at 20°C and 73% RH, wound up on a roll, and heated as it was at 40°C. Heat treatment was performed in an atmosphere for 3 days. Table 2 shows the properties of the obtained coated film. Comparative Example 5 Polypropylene film was coated with formulation (B) in the same manner as in Example 2, dried, air cooled at 33°C and 65% RH, wound onto a roll, and heated as it was in an atmosphere of 40°C for 3 days. I processed it. Table 2 shows the properties of the obtained coated film.

【table】 [Brief explanation of the drawing]

FIG. 1 is a perspective view showing the state of a covering film rolled up into a roll by a conventional method. 1...Covering film.

Claims (1)

[Claims] 1 Coat at least one side of the film with a coating liquid mainly composed of vinylidene chloride copolymer resin emulsion, dry, cool to 5 to 30°C, and then heat at 5 to 30°C for 35 minutes.
Wind up into a roll in an atmosphere of ~70% RH, 6
A method for producing a coated film, which comprises leaving the film roll at room temperature for at least an hour, then rewinding the film roll, and heat-treating the film in an atmosphere at 35 to 55°C for at least 6 hours.