JPH0436938B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for label packaging bottles.

(Prior technology) Conventionally, polyvinyl chloride-based shrinkable film was used as the material for labels used in bottle label packaging, but recently its toxicity has become a problem, and its transparency has also deteriorated. However, it has been pointed out that it is weak and has poor slippage, making it somewhat less suitable for mechanical packaging. For this reason, polypropylene-based films have come to be used as non-toxic shrinkable films in place of polyvinyl chloride-based films, but this film leaves avatars on the surface and not only deteriorates its appearance, but also shrinks. workability is poor because high temperatures are required and the temperature range in which shrinkage is possible is narrow;
There were drawbacks such as troubles easily occurring in terms of shrinkage temperature control.

(Problem to be solved by the invention) Therefore, in order to improve these drawbacks, it has been considered that polypropylene resins are further blended with appropriate resins such as butene, but these products are only polypropylene resins, so Although the disadvantages caused by this method can be improved, on the other hand, there are disadvantages such as blocking properties and weakening of the stiffness, and it is not possible to obtain a label packaging with a clean appearance and without wrinkles for the bottle.

On the other hand, with conventionally used shrinkable film for labels, the direction and size of shrinkage are not taken into consideration, and the width of the label on the labeled bottle cannot be maintained accurately, resulting in stable shrinkage. I couldn't get a packaged bottle.

In view of the above, the first object of the present invention is to package bottles with clean labels that are excellent in machine packaging suitability and are free from wrinkles, and to accurately maintain the width of the label on the labeled bottle. The second purpose is to provide stable packaging.

(Means for Solving the Problems) In order to achieve the above objects, the present invention provides a styrene-butadiene product with a styrene content of 65 to 90%, a butadiene content of 10 to 35%, and a melt index of 1.0 to 10.0 g/10 min. A composition containing 50 to 98% by weight of block copolymer and 50 to 2% by weight of polystyrene was
After extrusion film formation using a die extruder, a shrinkable film is created by uniaxially stretching the film using a tenter-type stretching machine.Next, a label is created using this film with the direction of stretching in the circumferential direction of the bottle. A structure was adopted in which the material was wrapped around a bottle and then heat-shrinked.

(Example) The method of the present invention will be explained below.

A styrene-butadiene block copolymer with a styrene content of 65 to 90% and a butadiene content of 10 to 35%, which is one of the compositions constituting the film that is the label material used for the label packaging of the present invention, is MI (melt index). Ix, ASTM-M1238E conditions)
It is in the range of 1.0 to 10.0 g/10 minutes, preferably 1.0 to 2.0 g/10 minutes. In this case, if it is less than 0.1 g/10 minutes, extrusion film formation becomes difficult, while if it exceeds 10.0 g/10 minutes, the film strength will decrease, which is not preferable.

In addition, polystyrene, which is another component of the film, is generally called polystyrene resin, but for example, it is a heat-resistant grade with a heat distortion temperature (according to the test method of JISK-6871). It is preferable that the material has heat resistance of 90°C or higher.

The present invention has a styrene content of 65 to 90% as described above,
Butadiene content 10~35%, MI 1.0~10.0g/
10 minutes styrene-butadiene block copolymer 50
The reason for this is as follows. For example, a film made solely of a styrene-butadiene block copolymer with a styrene content of 65 to 90% and a butadiene content of 10 to 35% is weak and has poor packaging and shrinking workability, and a film made solely of polystyrene is weak. The disadvantage is that it lacks impact resistance and is easily damaged.

On the other hand, in the present invention, the specific block copolymer and polystyrene are blended in specific weight percentages, thereby eliminating the drawbacks caused by these alone. In the present invention, the block copolymer 50
-98% by weight and 50-2% by weight of polystyrene is limited because if the block copolymer is less than 50% by weight or exceeds 50% by weight of polystyrene, the impact resistance of the film will be poor, causing breakage and cracking. It is easy to produce and is not practical, and on the contrary, if the copolymer exceeds 98% by weight,
This is because if the polystyrene content is less than 2% by weight, the elasticity becomes weak and the label packaging workability and shrinkage workability deteriorate.

The present invention uses the above-mentioned composition, but if the film is required to have a high degree of slipperiness, a well-known lubricant may be added. Examples of the lubricant include ethylene bisamide and fatty acid amide. Furthermore, an antistatic agent may be added if necessary, and examples of the antistatic agent include well-known ones such as glycerin fatty acid ester and sorbitan fatty acid ester.

Next, the composition blended above was extruded into a film using a T-die extruder, and then stretched uniaxially in a tenter type stretching machine to create a shrinkable film. By creating a circumferential label, wrapping the label around the bottle, and then heat-shrinking the label, the label is attached and integrated with the bottle.

At this time, the reason why the specific shrinkage imparting means as described above was adopted in the present invention will be described below.

It is well known that there are two methods for weft-uniaxially stretching a film: an inflation method and a tenter method. In the former method, the film is first extruded into a tube shape in the same direction as the extruder, and then stretched again in the tube shape in a direction perpendicular to the extruder. When the shrinkable film obtained in this way is used to label bottles, it shrinks in the circumferential direction of the bottle and simultaneously in the axial direction (vertical direction) of the bottle. direction)
Shrinkage also occurs, making it difficult to maintain the label width accurately and making it impossible to obtain stable shrink-wrapped bottles.

On the other hand, in the latter method, which is particularly adopted by the present invention, the film is extruded using a T-die and stretched using a tenter-type stretching machine, which makes it possible to suppress warp stretching in the same direction as the extruder as much as possible. A weft-uniaxially stretched film (shrinkable film) can be obtained. Therefore, if this shrink film is formed into an appropriate size, a label is made with its stretching direction in the circumferential direction, and the label is wrapped around a bottle and then heat-shrinked, the bottle will shrink in the circumferential direction, but the bottle will shrink in the circumferential direction. Since the contraction in the axial direction of the label is suppressed, the width of the label is maintained accurately.
Moreover, stable packaging can be performed.

Hereinafter, specific examples of the present invention will be described.

Styrene-butadiene block copolymer with MI of 2.0 g/10 minutes; 75% by weight (styrene content approx. 75%, butadiene content approx. 25%)
polystyrene (heat deformation temperature: 93°C); 25% by weight A composition containing the above was extruded into a film using a T-die extruder, and then stretched 3 times in the weft direction using a tenter-type stretching machine.
A shrinkable film with a thickness of 500 μm was obtained by stretching the film twice. This shrinkable film had good elasticity, good sliding properties, and was non-toxic.

Next, this shrink film is used to create a label with the stretching direction of the shrink film aligned with the circumferential direction of the bottle as shown in Figure 1 using an automatic label packaging machine (not shown), and this label is attached to the bottle. By wrapping and then heat shrinking, the labeled bottle shown in FIG. 1 was obtained.

The above mechanical packaging was carried out suitably, and the wrapped labels were wrinkle-free, had a clean appearance, had accurate widths, and were stable shrink-wrapped.

(Effects of the Invention) Since the present invention uses a composition with a specific formulation, it is not only non-toxic compared to conventional compositions, but also has strong elasticity and good slipperiness, resulting in excellent machine packaging properties. Furthermore, the present invention produces a shrinkable film stretched by a specific method, and produces a label with this film stretched in the circumferential direction of the bottle. Since this label is heat-shrinked after being wrapped around a bottle, the width of the label on the labeled bottle can be accurately maintained, stable packaging can be performed, and a bottle with a clean appearance without wrinkles can be obtained. It will be done.

[Brief explanation of drawings]

FIG. 1 shows a bottle obtained by the method of the present invention. 1...bottle, 2...label.

Claims (1)

[Claims] 1 Styrene content 65~90%, butadiene content 10~
At 35%, the melt index is 1.0 to 10.0g/10
Styrene-butadiene block copolymer 50~
A composition containing 98% by weight and 50-2% by weight of polystyrene was extruded into a film using a T-die extruder, and then uniaxially stretched using a tenter-type stretching machine to create a shrinkable film. A method for label packaging a bottle, characterized in that a label is created whose stretching direction is in the circumferential direction of the bottle, and the label is heat-shrinked after being wrapped around the bottle.