JPH0623890A - Production of label - Google Patents

Abstract

PURPOSE:To produce a label excellent in heat shrinkability and impact resistance by specifying the shrinkage factor of a polyolefinic foamed sheet constituting the label and the difference between the heat shrinkage factor of a polystyrenic film and that of the polyolefinic foamed sheet. CONSTITUTION:A label is used so as to be wound around a container and formed from a laminated sheet wherein polystyrenic films are laminated on both surfaces of a polyolefinic foamed sheet. In this case, the heat shrinkage factor of the polyolefinic foamed sheet at 160 deg.C in one direction is set to 30-70% and the difference between the heat shrinkage factors of the polystyrenic film and the polyethylenic foamed sheet at 150 deg.C in one direction is set to 40% or less. Printing is applied to the boundary surfaces of the polyolefinic foamed sheet and the polystyrenic films. By this constitution, a label excellent in physical property balance of heat shrinkability and impact strength can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a label which is used by being wrapped around a container.

[0002]

2. Description of the Related Art Conventionally, heat-shrinkable plastic films or sheets used as labels for one-way containers, particularly glass bottles, are manufactured from polyvinyl chloride resin or polystyrene resin. However, polyvinyl chloride resin has a problem of harmful gas generated during incineration. Further, a foamed sheet or a non-foamed film processed from a polystyrene resin has low impact resistance and its use range is restricted. On the other hand, polypropylene resin labels have also been developed, but although they have excellent impact resistance, non-foamed labels have a narrow heat shrinking condition, resulting in a low production speed or being wound in a glass bottle. Uneven, or
There is a problem that the water for washing and the liquid with which the filling is dropped enter the space between the container and the label without coming into close contact with each other. Foam sheets with improved heat shrinkability have also been developed. Labels made of polypropylene resin are inherently difficult to stick together with a solvent, and there is a restriction that they cannot be used as a labeler for laminating and winding end faces of the label with a solvent.

[0003]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention The present invention has been made to solve the above problems, and its purpose is to provide a heat-shrinkable performance of a polystyrene film,
It is an object of the present invention to provide a method for producing a label which has a function of sticking the end faces of the label with a solvent and also has an excellent impact resistance of the polyolefin foam sheet and which has an excellent heat shrinkability.

[0004]

Means for Solving the Problems Under the above-mentioned circumstances, the inventors of the present invention have made earnest studies on a label to be wrapped around a container, particularly a glass bottle, and as a result, found that a label in which a polystyrene film is laminated on both sides of a polyolefin foam sheet is a label. They have found that they are effective and have completed the present invention. That is, in the method for producing a label comprising a laminated sheet in which a polystyrene film is laminated on both sides of the polyolefin foam sheet of the present invention, the one-way heat shrinkage ratio of the polyolefin foam sheet at 150 ° C. is 30 to 70%. In addition, the label manufacturing method is characterized in that the difference between the heat shrinkage in one direction of the polystyrene film and the polyolefin foam sheet at the same temperature is within 40%.

The present invention will be described in detail below. The polyolefin-based foamed sheet in the present invention is composed of 100 parts by weight of polypropylene and 5 to 80 parts by weight of polyethylene,
The expansion ratio is 1.3 to 2.0 times, and the shrinkage ratio in one direction when immersed in an oil solution at 150 ° C. for 1 minute is 30.
~ 70%, and the shrinkage in the direction perpendicular to it is -10 to 10%
It is a foamed sheet having the following properties. The polypropylene used for the foamed sheet is polypropylene homopolymer, copolymer mainly composed of propylene and α-olefin such as 1-butene, and modified resins thereof, and the melt flow index (load) measured according to JIS K-6758. 2.16 kg (hereinafter abbreviated as MI)) 20 to 60 g / 10 minutes, preferably 30 to 5
It is 0 g / 10 minutes. The polyethylene used for the foamed sheet may be any of low density polyethylene, medium or high density polyethylene, linear low density polyethylene and the like, but low density polyethylene and linear low density polyethylene are particularly preferable. Moreover, MI (load 2.16 kg) measured according to JIS K-6760 is 20 to 60 g / 10.
Minutes, preferably 30 to 50 g / 10 minutes. Polyethylene 100 is used
5 to 80 parts by weight, preferably 20 to 60 parts by weight
Parts by weight. Outside this range, a sheet having a uniform and good surface cannot be obtained. The foamed sheet of the present invention may contain polypropylene, polyethylene and, if necessary, a colorant, an inorganic filler, an antistatic agent, and other additives. The expansion ratio and shrinkage performance of the polyolefin foamed sheet of the present invention depend on the mechanical strength required for coating the sheet on a bottle, the heat-sealing property and the impact strength required when using the coated bottle as a container and the adhesion after coating. Although determined, the expansion ratio is 1.3 to 2.0 times. If the expansion ratio is less than 1.3 times, it becomes difficult to uniformly generate bubbles and obtain a sheet having a uniform appearance. Further, the impact strength of the label after laminating the polystyrene film is insufficient, and the polystyrene film is largely damaged when the glass bottle coated with the label advances while colliding on the line, for example. On the contrary, a sheet having a foaming ratio of more than 2.0 times has large surface irregularities, and a uniform sheet cannot be obtained. The heat shrinkage rate of the label is measured by the shrinkage rate when it reaches 150 ° C, and is usually measured by a method of allowing it to stand in an oil bath at 150 ° C for 1 minute. The shrinkage ratio measured under this condition is 30 to 70% in one direction (longitudinal), and preferably in the machine direction (MD). When the shrinkage ratio is less than 30%, the end surface becomes wavy when coated on the bottle and does not adhere to the bottle. Also, if it exceeds 70%, printing process, laminating process,
It is easy to tear in processing processes such as slitting process and mounting process, and loss increases. On the other hand, in the direction (TD) perpendicular to that, -10 to 10
% Is preferable. When the shrinkage ratio of TD is out of the above range, the printed pattern is distorted when covered, which is not suitable. The thickness of the sheet is usually 0.05 to 0.25.
If it is less than 0.05 mm, it becomes difficult to mount it on the bottle, resulting in a large loss, and if it exceeds 0.25 mm, the rolled-up curl after lamination is large and the label is curved. The foam sheet used in the present invention is polypropylene,
Polyethylene, a foaming agent and, if necessary, various additives are added, foaming and melt-forming is performed by a known method so that the expansion ratio is 1.3 to 2 times, and then stretched in at least one direction at a temperature not higher than the melting point of polypropylene. To be manufactured. As the foaming agent used at this time, an organic foaming agent having a decomposition temperature higher than the melting point of polypropylene such as azodigalbonamide, dinitrosopentamethylenetetramine, or the like is preferable. The amount of the foaming agent used varies depending on the target expansion ratio and the type of the foaming agent, but is usually 0.3 to 1.0% by weight based on the resin mixture. A foaming aid may be used. Further, the stretching ratio is appropriately 3 to 10 times in at least one direction, and preferably 4 to 7 times. Further, this stretching may be carried out in multiple stages instead of one stage, and for the purpose of balancing, it may be slightly stretched in the direction perpendicular to the above stretching. In addition, it is preferable that both front and back surfaces of this film are subjected to corona treatment.

The polystyrene film used in the present invention is composed of general-purpose polystyrene (GPPS), high-impact polystyrene (HIPS), styrene-butadiene, maleic anhydride, methacrylic acid, and a copolymer resin of styrene, and a mixture thereof. The ratio is selected depending on the transparency of the film, the film forming property of the film, and the subsequent processability.
Further, rubber, an elastomer, a plasticizer, an antistatic agent, a lubricant or the like may be added for the purpose of adjusting flexibility and heat shrinkage performance.

The thickness of the polystyrene film is preferably 0.015 to 0.05 mm, and the heat shrinkage in one direction at 150 ° C. is 50 to 80%. The thickness is 0.
When the thickness is less than 015 mm, the loss is large even in the printing process, and the strength of wrapping the laminated label on the glass bottle or the PET bottle and bonding the end face is insufficient. If it exceeds 0.05 mm, it is difficult to stack and wind it into a roll. If the heat shrinkage in one direction is less than 50%, the label is restricted or the label winding speed is reduced. If the heat shrinkage rate exceeds 80%, the film will be torn in the printing process and the loss will increase. The polyolefin-based foamed sheet and the polystyrene-based film are laminated with their respective directions of large shrinkage aligned, but the difference between the heat-shrinkage rate of the polyolefin-based foamed sheet and the heat-shrinkage rate of the polystyrene-based film is within 40%. Is. If the difference exceeds 40%, wrinkles and the like are likely to occur in a portion that requires a large amount of shrinkage when heated and brought into close contact with the glass bottle, which lowers the commercial value. Further, it is preferable that the laminated surface of this film is subjected to corona treatment. Printing is performed on the boundary surface between the polyolefin-based film and the polystyrene-based film, but the printing can be performed on the polyolefin-based foam sheet or the styrene-based film without any problem. Preferred is a polyolefin foam sheet. The adhesive applied to the boundary surface between the polyolefin foam sheet and the polystyrene film is preferably a polyurethane adhesive. Polyurethane adhesive is 1
It is an adhesive obtained by reacting a normal polyisocyanate having two or more isocyanate groups per molecule with a polyether or polyester having aquatic groups at both ends. Specifically, hexamethylene diisocyanate, lysine diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), methylenecyclohexane 2,4
(2,6) diisocyanate, 1,3- (isocyanatomethyl) cyclohexan, isophorone diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, xylylene diisocyanate, metal xylene diisocyanate An adhesive obtained by reacting a compound containing two or more isocyanate groups per molecule with a polyester, polyether, glycol or the like having a hydroxyl group at the terminal. Preferred is a two-pack type adhesive obtained by reacting a water-adducted polyisocyanate of hexamethylene diisocyanate with a polyester having hydroxyl groups at both ends, for example, Trademark Adcode AD (manufactured by Toyo Morton Co., Ltd.), Trademark Orestar. Some are commercially available under the names such as NP-1100 / NL2448 (manufactured by Mitsui Toatsu Chemicals, Inc.). To apply the polyurethane adhesive to the interface between the polyolefin foam sheet and the polystyrene film, a normal dry lamination device can be used, and the polystyrene film is laminated on both sides of the polyolefin foam sheet at one time. However, there is no problem even if they are laminated on each side. The coating amount of the polyurethane adhesive is preferably in the range of 0.5 to 5 g / m ² . A laminated sheet of a wide polyolefin-based foamed sheet and a polystyrene-based film thus printed is cut into a desired width for one row and then rolled up.
This printing sheet, which is continuously repeated in one line, is cut into individual sheets at a predetermined position by a labeler to form a label for each leaf, and at the same time, it is continuously attached to a glass bottle or a PET bottle. Further, depending on the shape of the container, the label is heated and brought into close contact with the glass bottle or PET bottle.

【Example】

The present invention will be described below with reference to typical examples. Example 1 [Polyolefin Foamed Sheet] 100 parts by weight of polypropylene having MI shown in Table 1 and polyethylene having MI shown in Table 1 were used in an amount of 0.5% by weight based on this resin composition. Azodicarboxylic acid amide was added, and the mixture was extruded from a T-die using an extruder having a diameter of 65 mm.
The film was stretched twice to obtain a foamed sheet having a thickness of 0.12 mm. The expansion ratio and shrinkage ratio of these foamed sheets were measured. The results are shown in Table 1. [Polystyrene film] 20 parts by weight of a styrene-butadiene block polymer (K resin; manufactured by Philips), GPPS (Topolex; manufactured by Mitsui Toatsu Kagaku) 75
Parts by weight and HIPS (Topolex; manufactured by Mitsui Toatsu Chemical)
B. 5 parts by weight with a 40 mmΦ extruder. U. The film was formed by the inflation method with R of 2.3, and when heated at 150 ° C, the flow direction (MD) was 75% and the direction perpendicular to it (T
A film having a thickness of 0.025 mm, which is 11% in D).
The polyethylene film and the polystyrene film were attached to each other with a two-component polyurethane adhesive (Ad Code; manufactured by Toyo Morton) to obtain a laminated film having a three-layer structure. The heat shrinkage ratio of this film (immersion in an oil bath at 150 ° C. for 1 minute) was 45% in MD and 5% in TD. This laminated film was slit into a ring shape having a width of 100 mm and then cut into a length of 220 mm to obtain a label.
Wrap the label along a glass bottle with a body diameter of 67 mmΦ and shoulders of 40 mmΦ, and wrap the mating part with tetrahydrofuran (T
It was adhered with HF) to form a cylindrical body. After that, the label was heated together with the glass bottle so as to be closely attached to the bottle. The label did not delaminate even when heated, and the appearance after shrinkage was beautiful. Vibration test in which bottles with this label are repeatedly collided with each other (9 test samples are placed in a cardboard box, 120 cycles / minute of vibration is performed for 10 minutes,
The appearance of the label was not broken and the joint was not peeled off.

Examples 2 to 4 Laminated sheets were produced in the same manner as in Example 1 except that the polyolefin foamed sheet or polystyrene film shown in Table 1 was used. In addition, the produced sheet was evaluated in the same manner as in Example 1, and the results are also shown in Table 1. The appearance after shrinkage was also good, and there was no label breakage or peeling of the mating part even when a glass bottle with a label was subjected to a vibration test.

Comparative Examples 1 to 4 Laminated sheets were prepared in the same manner as in Example 1 except that the polyolefin foamed sheet or polystyrene film shown in Table 1 (continued) [Table 2] was used. The produced film was evaluated in the same manner as in Example 1, and the results are also shown in Table 1 (continued) [Table 2]. In the case where the polyolefin foam sheet has a small MD heat shrinkage at 150 ° C., even if it is wound around a glass bottle and then heated for further contact, it does not shrink uniformly and the commercial value is lost. On the other hand, the MD shrinkage of polystyrene film is 1
If it is less than 50% at 50 ° C., even if the laminated film is heated, it does not shrink uniformly and the commercial value is lost. In addition, if the thickness of the polystyrene film is small, a poor appearance occurs in a vibration test.

Comparative Example 5 A label was prepared and evaluated in the same manner as in Example 1 except that the ethylene-vinyl acetate copolymer was used as the urethane adhesive. During the shrinkage, many fine cracks were generated on the surface of the laminated sheet and the appearance was deteriorated.

[0012]

[Table 1]

[0013]

[Table 2]

[0014]

According to the present invention, a label having a good balance of physical properties, which is excellent in heat shrinkability and impact strength, can be obtained. That is, the heat shrinkability was improved by laminating the polystyrene film, and it became possible to adhere the label to a glass bottle or a PET bottle. In addition, this label has polystyrene films laminated on both sides of the polyolefin foam sheet, so not only can the heat-bonding of the overlapping parts be done, but solvent bonding is also possible. Spread.

Front page continuation (72) Inventor Shizozo Nishiba 6-9 Nihonbashi Hakozakicho, Chuo-ku, Tokyo Sun Lily Co., Ltd.

Claims (2)

[Claims] 1. A method for manufacturing a label comprising a laminated sheet in which a polystyrene film is laminated on both sides of a polyolefin foam sheet, wherein the one-way heat shrinkage ratio of the polyolefin foam sheet at 150 ° C. is 30 to 7.
A label manufacturing method, wherein the difference between the polystyrene film and the polyolefin foamed sheet at one temperature is 0%, and the difference in heat shrinkage in one direction is 40% or less. 2. A method for producing a label comprising a laminated sheet according to claim 1, wherein printing is performed on a boundary surface between the polyolefin foam sheet and the polystyrene film.