JPH06110387A - Production of laminated label - Google Patents

Abstract

PURPOSE:To provide the laminated label which does not curl in spite of heating or curls to the rear side even if the label curls by previously stretching a base material before a surface coating material and this base material are thermally adhered. CONSTITUTION:The laminated label is produced by laminating the surface coating material provided with a hot melt adhesive layer on the front surface of the base material provided with release paper via an adhesive layer on the rear surface in such a manner that the hot melt adhesive layer and the front surface of the base material come into contact with each other. Incidentally, the base material consisting of a plastic film or paper is deformed when the material is stretched. The material tends to restore the initial shape when the material is heated and the energy larger than the energy at the time of the deformation is applied thereto after the above-mentioned stretching. If the surface coating material is, thereupon, thermally adhered thereto by utilizing this phenomenon, the base material is thermally shrunk by the heating of this time and the curling of the base material is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of producing a laminated label which can be curled even when heated or curled on the back side even when curled.

[0002]

2. Description of the Related Art In order to give a product an aesthetic appearance, to explain the characteristics of the product, or to emphasize the design, etc.
Various labels (including stickers) are attached to the product directly or on the package of the product. The surface of these labels is covered with a transparent plastic film in order to enhance the strength, improve the anti-contamination property and the weather resistance, and impart gloss and enhance the appearance. In addition to a transparent plastic film, a label may be coated with paper or a matte matte film to give the label a different appearance.

As a method for coating the surface of a base material with such a plastic film or paper, there is disclosed in Japanese Utility Model Laid-Open No. 59-1.
89669, JP-A-56-42652, JP-A-59-24666, JP-A-60-73942.
JP-A-60-236727, JP-Sho 63-63
In JP-A-119639 and JP-A-62-35834, (1) a plastic film or paper provided with release paper via an adhesive layer is attached to the surface of a base material while removing the release paper. A method of attaching or (2) a method of thermally adhering a film or paper coated with a hot melt adhesive to the surface of a substrate is disclosed. Also, the above
An apparatus for carrying out the method (2) is disclosed in JP-A-3-634.

Of the laminated labels obtained as described above, the case (1) cannot be said to be a rational production method, and the case (2) uses a film coated with a hot melt adhesive as a base material. Since the film is heated to a temperature of 80 to 160 ° C. when it is heat-bonded to the sheet, the film is thermally shrunk and the label curls on the front side. Such curl not only causes various obstacles when the label is automatically or manually attached to the product, but also causes a problem that the label is peeled off after the attachment. In particular, this problem is remarkable when the label curls to the front side, and does not become a big problem when the label curls to the back side.

In order to prevent the occurrence of the curl,
Japanese Unexamined Patent Publication No. 4-67087 discloses the use of a heat-resistant film having a specified heat shrinkage ratio as a surface coating material, but it cannot completely prevent the occurrence of curling, and the label is placed on the back side. I couldn't make it curl.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for producing a laminated label which can obtain a laminated label which does not curl when heated or curls on the back side even when curled. is there.

[0007]

Means for Solving the Problems As a result of various studies on the above-mentioned problems, the present inventors have preliminarily stretched the base material before heat-bonding the surface coating material and the base material in the method for producing a laminated label. Then, the present inventors arrived at the present invention by finding that the troubles caused by curling can be eliminated. That is, according to the experiments conducted by the present inventors, the degree of curl generated on the label is related to the heat shrinkage rate of the surface covering material laminated on the surface of the label. And it becomes easy to curl to the front side of the label. This tendency is particularly remarkable when a plastic film is used as the surface coating material. Also, when using paper,
Although the shrinkage due to heat is relatively small, the shrinkage due to dehydration is added, and the curl also occurs on the front side of the label. Therefore, as a result of earnest research, in order to eliminate the curl or to curl the back side of the label, the contraction rate of the base material and the surface coating material should be equal, or the contraction rate of the base material should be larger than that of the surface coating material. Based on these findings, the inventors arrived at the present invention.

That is, according to the present invention, a surface coating material having a hot-melt adhesive layer provided on the surface of a base material provided with a release paper on the back surface via a pressure-sensitive adhesive layer is used to form a hot-melt adhesive layer and a base material. In the method for producing a laminated label by laminating so that the surface is in contact with each other, and thermally adhering the laminated label, the substrate is stretched in a step prior to the step of thermally adhering the surface coating material and the substrate. The main point is the manufacturing method.

Next, the present invention will be described in detail. As the base material of the laminated label in the present invention, usually, a plastic film or sheet, paper, synthetic paper, knitted fabric, non-woven fabric, a composite thereof and the like are used. These base materials are generally less likely to undergo heat shrinkage as they are than surface coating materials. By the way, a base material such as a plastic film or a paper is deformed when stretched and then heated to give more energy than the energy at the time of deformation, so that a so-called heat shrinkage phenomenon occurs in which the material returns to its original shape. Therefore, by utilizing this phenomenon, when the base material is stretched in a step before the step of thermally adhering the surface coating material and then the surface coating material is heat-bonded, the base material thermally shrinks due to the heating at that time, and the curling occurs. Can be prevented.

In the present invention, the method of stretching the base material is not particularly limited, but a method of passing the base material through one or more sets of nip rolls while nipping them and stretching at a peripheral speed difference between the nip rolls, one set. A method of stretching with the peripheral speed difference between the rolls while applying the rolls in a plow shape, one or more round bars,
Square rod (triangular, square or polygonal cross section)
Is applied to the base material so as to be perpendicular to the longitudinal direction of the base material, and a method of stretching by rubbing with the rod-like material while applying tension to the base material, or a method of stretching with a combination of these stretching methods, Can be mentioned. These rolls or rods may be heated in order to enhance the effect.

The step of stretching the substrate is not particularly limited as long as it is before the step of thermally adhering the surface coating material. Generally, the manufacturing process of a hot-melt type laminated label includes a substrate unwinding process, a printing process, a heat-bonding process, from the upstream side.
Although it is roughly divided into a die-cutting step, the stretching step of the substrate in the present invention is preferably performed between the substrate unwinding step and the printing step or between the printing step and the heat-bonding step.

Further, the degree of stretching of the base material in the present invention is preferably determined in accordance with the heat shrinkage amount of the surface coating material during heat bonding, and the heat shrinkage amount of the surface coating material during heat bonding is the surface coating material. It is preferable to determine the heat shrinkage amount to be equal to or more than the heat shrinkage amount during heat bonding. The determination method is, for example, to manufacture a laminated label without stretching the base material and measure the degree of curl, and then gradually increase the stretching amount of the base material so that the curl is zero or on the back side. The amount of stretching is fixed when the state of occurrence occurs. The stretching amount is generally defined by the strain amount of the base material during stretching. That is, it is expressed as a percentage of the value obtained by dividing the dimensional difference before and after stretching by the dimension before stretching. According to the experiments by the present inventors, the stretching amount is 0.01% or more, particularly 0.1%.
The above is preferable. If the amount of stretching is too large, the printed layer will be distorted after heat bonding, so 6% or less, especially 4%.
The following are preferred. By doing so, it is possible to produce a label with less curl even when a surface coating material having a large heat shrinkage rate is used.

The surface coating material which can be used in the present invention includes plastic films such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and other polyester resins,
Polyamide resin such as nylon 6, nylon 66, nylon 46, polyvinyl alcohol resin such as polyvinyl alcohol and polyethylene vinyl alcohol, polyphenylene sulfide resin, polyimide resin, fluorine resin such as polyvinyl fluoride and polyvinylidene fluoride, poly 4
-Methylpentene-1 resin and the like are mentioned, and among the above materials, polyester resin is preferable in consideration of thermal dimensional stability, water absorption dimensional stability, economical efficiency and the like. Although these can be used even in an unstretched film, a biaxially stretched film generally has higher strength and elastic modulus, and has better workability during label production.

The dicarboxylic acid component of the polyester resin includes malonic acid, succinic acid, suberic acid, adipic acid,
Aliphatic dicarboxylic acids having 20 or less carbon atoms such as azelaic acid, sebacic acid, dodecanedioic acid, tetradecanedioic acid, and eicosanedioic acid; long-chain aliphatic dicarboxylic acids such as dimer acid;
Alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid,
Examples thereof include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, and 1,5-naphthalenedicarboxylic acid.

As the diol component, aliphatic glycols such as ethylene glycol, propylene glycol, butanediol and hexanediol, polyols such as diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol and polypropylene glycol, Examples thereof include alicyclic diols such as cyclohexanediol and cyclohexanedimethanol, and their derivatives.

Of the polyester resins, biaxially stretched polyethylene terephthalate is preferable in view of thermal dimensional stability, mechanical strength and economy. The polyester resin may be modified as long as these properties are not impaired. Further, the surface of the film may be subjected to processing such as sand mat processing, coat mat processing and coloring processing.

As the composition constituting the hot melt adhesive layer, one containing no organic solvent in its composition is used. As the base polymer of the hot melt adhesive, polyethylene, ethylene-vinyl acetate copolymer, ethylene acrylate copolymer, atactic polypropylene,
Thermoplastic polymer compounds such as polyamides, polyesters, styrene-butadiene block copolymers and styrene-isoprene copolymers can be mentioned. In particular, the ethylene-based copolymer is excellent in adhesiveness, flexibility, flexibility, heat resistance, heat melting property, and fluidity, and is inexpensive, and thus can be preferably used. Particularly, an ethylene-vinyl acetate copolymer is preferably used, and the copolymer component is in a molar ratio of ethylene: vinyl acetate of 100: 1 to 100:
It is preferably 50, particularly 100: 10 to 100: 30. When the molar ratio of the copolymer component is less than 1 vinyl acetate to 100 ethylene, the adhesiveness is poor, and when the molar ratio exceeds 50 vinyl acetate to 100 ethylene, the heat resistance tends to be poor.

The composition constituting the hot melt adhesive layer may contain a tackifying resin for the purpose of improving the adhesiveness and workability of the base polymer. Examples of the tackifying resin include petroleum-based C9 resin, petroleum-based C5 resin or mixed resin thereof, natural rosin, rosin ester, terpene resin,
Terpene phenol resin, terpene styrene resin, hydrogenated resin such as the above resins, xylene resin, styrene-α-
Methylstyrene copolymer resin, paraffin wax, microwax, polyethylene wax, etc. are used.
Further, a plasticizer, an antioxidant, a filler and the like can be added. Regarding the hot melt adhesive, 1 part of the tackifying resin is added to 100 parts by weight of the former with respect to the base polymer.
˜300 parts by weight, preferably 5 to 30 parts by weight may be added.

In consideration of practicality, the softening point of the hot melt adhesive is 90 to 15 (ring and ball method JISK2531).
It is preferable to use one having a temperature of 0 ° C, preferably 40 to 50 ° C.
Melt flow rate (MFR) is 5-100 at 190 ° C
It is recommended to use g / 10 min, preferably 10 to 30 g / 10 min. The adhesive strength is preferably adjusted to 200 g / cm ² or more with respect to the heat resistant film.

Bonding of a base material having a release paper on the back surface with a pressure-sensitive adhesive layer and a surface coating material having a hot-melt adhesive layer is performed by joining the surface of the base material and the hot-melt adhesive layer provided on the coating material. Together and are passed between heating rolls. At this time, the roll temperature is preferably 90 to 180 ° C., the pressure is 1 to 10 kg / cm ² , and the passing speed is 5 to 120 m / min in consideration of productivity. At this time, in order to increase the adhesive force on the surface of the base material, surface treatment such as corona discharge or providing an anchor coat layer may be performed. Laminated label obtained as described above, after passing the heating roll,
The label shape is adjusted and cut into an appropriate shape, and the release paper on the back side is peeled off to adhere to the product.

[0021]

EXAMPLES Next, the present invention will be specifically described with reference to Examples. Examples 1 to 5 and Comparative Example 1 100 parts by weight of ethylene-vinyl acetate block copolymer resin (80 parts by weight of ethylene component, 20 parts by weight of vinyl acetate component) and 5 parts by weight of hydrogenated terpene resin were heat-melted and sufficiently heated. After mixing with stirring, pelletization was performed using a vent type granulator. A biaxially stretched polyethylene terephthalate (PET) film having a thickness of 12 μm is subjected to corona treatment, further anchor-coated, and the above-mentioned adhesive pellets are extruded by using an extruder to obtain a thickness of 20 μm. A melt adhesive layer was provided.

On the other hand, a Miracoat paper having a release paper provided on the back side via an adhesive layer is passed through two rolls with nip rolls, and the peripheral speed difference between the two rolls is variously changed while being sandwiched by the nip rolls. After stretching with the stretching amount shown in (1), a printing layer was provided on the surface of the Miracoat paper, and the hot melt adhesive layer and the printing layer were superposed and nipped with a heat roll to perform heat bonding.
The conditions for heat bonding are a heat roll temperature of 100 ° C and a pressure of 3 kg / cm.
^{2. The} speed was 10 m / min. (The non-stretched one was used as Comparative Example 1.) The curl property of the obtained laminate was measured, and the results are shown in Table 1. Regarding the curl property, each A4 size laminated film was placed on a flat plate, and the maximum amount of lifting from the flat plate was measured.

Examples 6 to 9 Synthetic paper (manufactured by Tamago Yuka Co., Ltd., trade name "Yupo") provided with a release paper on the back side with an adhesive layer interposed between two rolls and triangular rods alternately. After passing through a stretching device arranged in a plow shape and stretching the synthetic paper with the stretching amount shown in Table 1 by utilizing the peripheral speed difference between two rolls, a printing layer is provided on the surface of the synthetic paper.
The hot-melt adhesive layer of the same surface coating material as in Example 1 was overlaid and heat-bonded by nipping with a hot roll. The conditions for thermal bonding are: hot roll temperature 90 ° C, pressure 4 kg / cm ² , speed 1
It was 2 m / min. The results of measuring the curl properties of the obtained laminate are shown in Table 1.

[0024]

[Table 1]

As is apparent from Table 1, it is understood that the curl property of the laminated label can be adjusted by stretching the base material in the step prior to the step of thermally adhering the surface coating material.

[0026]

According to the present invention, it is possible to manufacture a laminated label which does not curl when heated or curls on the back side even when curled.

Claims (1)

[Claims] 1. A surface coating material provided with a hot-melt adhesive layer on the surface of a base material having a release paper on the back side with an adhesive layer interposed between the hot-melt adhesive layer and the surface of the base material. In the method for producing a laminated label by laminating and heat-bonding the substrate as described above, the substrate is stretched in a step prior to the step of thermally adhering the surface covering material and the substrate.