JPS6233639A - Polyolefin group film coated with polyvinylidene chloride resin - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a coated polyolefin film with excellent suitability for heat seal packaging. More specifically, the present invention relates to a coating film that has good packaging stability during high-speed automatic packaging and can be packaged without impairing the packaging appearance of the inner package.

(Prior Art) Conventionally, polyvinylidene chloride resin-coated polyolefin films have been widely used as packaging materials because of their excellent gas barrier properties, heat sealability, transparency, etc.

For example, a heat-sealable polyvinylidene chloride resin-coated polyolefin film is used as the outer packaging film for cassette tapes, boxed pharmaceutical products, confectionery, etc. In this case, this outer packaging film is generally used to make it easier to open. Packaged with tamper tape heat-sealed on the inner packaging side.

Furthermore, the polyolefin film that is the base material for such packaging films is usually heat-shrinkable during the packaging process so that it can be heat-shrinked to give a neat packaging finish. The heat sealing temperature for 1 hour was appropriately selected.
The application of short-time, high-temperature conditions is being considered;
At that time, as described above, since the base film has heat shrinkability, heat shrinkage wrinkles are likely to occur in the heat sealed portion due to high temperature conditions.

Product value is decreasing. More curls occur.

There are drawbacks such as the possibility of the product being caught in high-speed automatic packaging machines.

(Means for Solving the Problems) In order to solve these drawbacks, the inventors of the present invention have made intensive studies and found that by using a coated polyolefin film that has heat shrinkage characteristics within a limited range, I discovered that there were no wrinkles or curls even if I partially heat-sealed it.

The present invention has now been completed.

Namely, the heat-sealable polyvinylidene chloride resin-coated polyolefin film of the present invention has a heat shrinkage stress of 5 to 50 t/15 m width in the longitudinal direction and 1 in the transverse direction at 120°C.
0-100 f715 width, preferably lengthwise 10-4
0 g/l 5mm width, horizontal direction 80~? 0r/ls, width, and heat shrinkage during heat sealing at 185°C is 0.5 to 2.5 inches in both vertical and horizontal directions, preferably 0.8 to 2
．． 0%.

The heat shrinkage stress at 120° C. is 50 F/15 width or more in the longitudinal direction and 1 OQ g/15 inch width or more in the transverse direction.

When the tear tape is heat-sealed using a high-speed automatic packaging machine, the heat-sealed area is narrow and heat-treated in two localized areas of 1 to 8 parts.
Curling occurs due to an unbalance in the thermal shrinkage behavior of the tear tape and the covering polyolefin film, and the packaging film gets caught in a part of two machines during the process of packaging cassette tapes, etc. feeding becomes not smooth. As a result, the packaging machine frequently stops, making it difficult to manage the packaging process and reducing productivity.

Also, the heat shrinkage rate during heat sealing at 185℃ is 2.5.
If the temperature exceeds 1, the heat shrinkage wrinkles will become severe at the heat-sealed parts of the bottom, bottom, and body parts when audio cassette tape cases, etc. are packaged, reducing the commercial value of the packaged product.
Undesirable.

On the other hand, the heat shrinkage stress at 120°C is 5g/15 in the longitudinal direction.
When packaging cassette tapes, etc., the heat shrinkage rate during heat sealing at 185° C. is 0.5% or less.

It is known that the heat shrinkage properties of the coated polyolefin film are good for preventing wrinkles during packaging, but even if the coated polyolefin film meets these conditions, the film of the present invention does not meet the requirements for tape sealing. The processability is poor due to curls and wrinkles in the heat-sealed part and the appearance of the packaging is also poor.

Examples of the polyolefin film used as the base material include biaxially oriented polypropylene film, unstretched polypropylene film, and unstretched polyethylene film. As shown in the examples, the next step is coating drying.

Since the shrinkage rate and shrinkage stress are reduced, a raw fabric with a desired shrinkage rate and shrinkage stress can be selected from commercially available products, or it can be prepared by a conventional method through film forming, stretching heat treatment, etc.

The polyvinylidene chloride resin coated to impart heat-sealing properties preferably has a vinylidene chloride content of 90% or less, and if it exceeds 90%, the heat-sealing properties deteriorate. Further, the coating amount of the polyvinylidene chloride resin is not particularly limited, although the thickness of the coating is usually 1 to 2 microns in many cases. The method for forming the coating is as follows: 1. Usually, a solution or emulsion is applied to one or both sides using a Mayer bar, air knife, dipping, or reverse roll method and dried. Other combinations as required.

For example, an anti-blocking agent, a slip agent, an antistatic agent, etc. may be used in combination.

Before applying the above polyvinylidene chloride resin cloth.

It is also possible to perform corona treatment on the surface of the polyolefin film to be coated and further provide an anchor coat layer.

(Functions and Effects) Since the coated polyolefin film of the present invention has limited heat shrinkage stress at 120°C and heat shrinkage rate at 185°C, the temperature control period (110 to 170 The heat shrinkability in "C) is moderate, so even if the packaging method is subjected to localized high-temperature and short-time heat action, there will be no heat shrinkage wrinkles and the finished product of the packaged product will be good.0 The following 9 inventions will be explained using examples.

The method for measuring the physical properties of the film shown in the Examples is as follows.

1. Heat shrinkage stress A 15m x 100 sample was placed under tension.

Fix the top and bottom with clips, and connect a measuring device (manufactured by Koso Shokin) with a strain gauge (Toyo Baldwin, 100 (for l)) connected to the upper end and a recorder, and in this state sample '!1l-120 It was immersed in a glycerin bath at 0.degree. C. for 1 second.

The behavior at this time was recorded on a recorder, and the heat shrinkage stress (V15 width) was measured.

2. Heat shrinkage rate during heat sealing: 50 x 150 m Draw two marked lines on the sample with a spacing of 100 m, use a bar type heat sealer with a length of 800 and a width of 10, and a temperature of 185°C. After crimping the bar so that it spans the two marked lines under the conditions of 1 crimping pressure direction of 10 Mi and crimping time of 0.25 seconds, the distance between the marked lines after crimping (L wmm ) was measured and the primary The thermal shrinkage rate was calculated using the formula.

Example 1 After corona treatment (molecular tension 38 dynes/α) was performed on both sides of the 92-axis stretched polypropylene film shown in Table 1, 10 parts of Coronate L (Japan Polyurethane, 75%) and Vylon 308 (Toyobo A mixed solution of 100 parts of ethyl acetate and toluene at a lO% concentration of 100 parts of ethyl acetate and toluene was coated as an anchor using a gravure roll to a coating amount of 0.8 sheets, and then dried at 90'C for 10 seconds. Next, the following polyvinyl chloride IJ resin emulsion (
After coating with an air knife to a thickness of 8 seams using a top layer of 40% (concentration: 40%), it was dried at 90° C. for 10 seconds. Furthermore, perform the same operation as above to make one double-sided polyvinyl chloride I.
A biaxially oriented polypropylene film coated with Jden resin was obtained. Next, it was aged at 40°C for 248 hours, and packaging suitability was evaluated.

Characteristics and evaluations of the obtained above-mentioned coated film were performed, and continuous packaging tests were conducted on audio cassette tape cases using this film using a high-speed automatic packaging machine.

The results are shown in Table IK. As you can see from this result,
The suitability for high-speed automatic packaging and the finish of the heat-sealed part were also good, and the two effects of the present invention were clear.

Top coating agent formulation Polyvinylidene chloride resin emulsion (solid content 50%) 100 parts Silica fine powder 0.25 parts Paraffin wax (solid content 30%, m, p, 60°C) 4.0 parts Quaternary ammonium salt (solid content) 60%) 1.0 part Comparative Examples 1 to 2 Biaxially oriented polypropylene films coated with polyvinylidene chloride resin on both sides of the original biaxially oriented polypropylene film shown in Table 1 were prepared in the same manner as in Example 1. did. Characteristic evaluation of the obtained above-mentioned coated film and continuous packaging test were conducted in the same manner as in Example 1. The results are shown in Table 1. As can be seen from these results, it can be seen that when films that do not belong to the present invention are used, suitability for high-speed automatic packaging and packaging conditions are inferior.

[Margin below]

Comparative Example 8 As a base film, the heat shrinkage rate at 50°C is 0.78 in the vertical direction.
A polyvinylidene chloride resin-coated OPP film was produced in the same manner as in Example 1, except that an OPP film having a % width of 0.51% and a heat shrinkage rate of 4.9% in length and 8.1% in width at 120°C was used. . Its performance is shown in Table 2. Obtained fiO
When PP film was used for high-speed automatic packaging of paper case manual rails, wrinkles occurred due to stoppage due to curling at the tape sealing part and excessive heat shrinkage during heat sealing of the opening, bottom, and body. However, the running performance of the packages was poor and the packaging machine frequently stopped.

The heat shrinkage rates at 120°C and 50°C were measured as follows.

A marked line is drawn approximately at the center of the sample having a heat shrinkage rate of 1100 w x 100 at 120° C. in the vertical and horizontal directions, and the distance between the marked lines is measured (1 otai) in the vertical and horizontal directions using a caliper. This sample is 12
Leave it in the open at 0°C for 15 minutes.

It was taken out and measured again (Lm)j, and the heat shrinkage rates in the vertical and horizontal directions were calculated using the following calculation method.

Heat shrinkage rate at 50°C Except for measurements after being left in an oven at 50°C for 4 days,
The heat shrinkage rate was determined in the same manner as in the case of 120°C.

Claims (1)

[Claims] Thermal shrinkage stress at 120°C is 5 to 50 g/15 in the longitudinal direction.
mm width, horizontal direction 10-100g/15mm width and 13
A heat-sealable polyvinylidene chloride resin-coated polyolefin film having a heat shrinkage rate of 0.5 to 2.5% in both the longitudinal and lateral directions when heat-sealed at 5°C.