JP2003263113A - Thermosensitive adhesive label for container and method for additionally setting the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermosensitive adhesive label which can be set additionally to containers, such as PET (polyethylene terephthalate) bottles, by superposed parts at both ends having higher strength of adhesion. <P>SOLUTION: The thermosensitive adhesive label (1) for containers is set additionally to the container (2) by winding the label around the container, superposing both ends, and pressing and heating the superposed segments (3) by thermosensitive tacky adhesive layers (4 and 4a) disposed on the under surfaces of both ends. The thermosensitive tacky adhesive layers (4) disposed on the under surfaces of the ends of the label existing in the upper parts of at least the superposed segments (3) at both ends are composed of expandable thermosensitive tacky adhesives containing 5 to 30%, by weight, heat expandable particulates. The label is more effective to the semi-rigid containers, such as the PET bottles. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved heat-sensitive adhesive label for containers and a method of attaching the same. The label is more effectively used as a label for a polygonal or cylindrical (soft) plastic bottle such as a PET bottle.

[0002]

2. Description of the Related Art As one of means for sticking a non-shrinkable label to a plastic bottle or the like, there is a method using a heat-sensitive adhesive label. The label is one in which an adhesive resin is applied to the back surface of a printed film, and prior to sticking to the bottle or the like, it is first heated to a temperature at which the adhesiveness is developed in advance, and the bottle or the like. First, attach the tip to the side of the body of
Then, it is attached to the side surface while rotating and twisting, and temporarily stopped in a state where the rear end portion is superposed. Then, the superposed portion is pressed at a predetermined pressure and heated at a higher temperature to be closely fixed.

Regarding the heat-sensitive adhesive label for containers, many patent applications have been made mainly for those relating to the components of the heat-sensitive adhesive, such as sticking means and its device. Among them, the present invention provides a more improved heat-sensitive adhesive and a method for applying the same, with the following problems.

[0004]

One of the problems to be solved is to further enhance the adhesion of the polymerized portions on both ends of the label. The adhesive strength of the conventional heat-sensitive adhesive may be insufficient in some cases, and there is a concern that it may come off during handling. By raising this to a higher level, this is to eliminate this anxiety.

Secondly, the adhesion of the polymerized portions on both ends of the label, which is performed after the container is rotated, is to obtain a sufficient adhesion force with a lower pressure, particularly regarding the pressing condition at that time. In particular, when the container is a semi-soft bottle such as a PET bottle, there is a concern of depression due to pressing, and therefore it is required to carry out at a lower pressure. This leads to a speeding up of the sticking process.

Thirdly, it is easy to remove the adhesive label from the used container. Regarding container recycling, we start by separating the adhesive label from the container body, but it is easy to separate it.
It also needs to be quick. It is also necessary that the adhesive layer does not remain on the container body during this separation.

[0007]

Means for Solving the Problems The above problems can be achieved mainly by the heat-sensitive adhesive label for containers according to claim 1 and the method for applying the label to a container according to claim 5.

In the first aspect of the invention, the heat-sensitive adhesive layer (4, 4a) is placed in the container (2) and polymerized at both ends, and the polymerized part (3) is provided on the lower surface of both ends.
A heat-sensitive adhesive label (1) for a container, which is heat-pressed and attached, wherein the heat-sensitive adhesive layer provided on the lower surface of the label end located at least above the polymerized portion at both ends is heated and foamed. A heat-sensitive adhesive label for containers, comprising a foamable heat-sensitive adhesive containing 5 to 30% by weight of functional particles.

Further, claim 1 has a dependent invention preferably achieved by the inventions described in claims 2 to 4.

On the other hand, according to the attachment method invention of claim 5,
Each of the following steps (A) to (C) is sequentially performed, which is an effective method applied to any of the labels provided in claims 1 to 4. (A) A first step in which the entire heat-sensitive adhesive label (1) for containers cut into a predetermined size is heated at a temperature equal to or lower than the foaming temperature of the foamable heat-sensitive adhesive to develop an adhesive force,
(B) A second step in which the tip portion of the label exhibiting the adhesive force is attached to the side surface of the container, and then the container is rotated to rotate so that the rear end portion becomes the upper surface, C)
And a third step of heating the polymerized portion while pressing it at a temperature higher than the foaming temperature of the foamable heat-sensitive adhesive to adhere and fix it.

A sixth aspect of the invention is a dependent invention of the fifth aspect and is provided as a preferred invention. Each of the above inventions will be described in detail below in the following embodiments.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, with respect to claim 1, the overall structure thereof is illustrated in the cross-sectional view of FIG. 1, and will be described in brief with reference to this. (1A) in the drawing is a cross-sectional view showing a state where the label of the present invention is wound around the container (in a non-contact state). That is, the foamable heat-sensitive adhesive layer 4 is formed on the lower surface of the part 3 where both ends are polymerized.
The heat-sensitive adhesive label 1 for a container (hereinafter simply referred to as label 1) provided with 4 and 4a is cleaved on the body of the container 2. Then, (1B) shows the overlapping portion 3 in an enlarged manner. Here, 1a is a support.

The label 1 basically has a structure in which the necessary printing is applied to the inner surface of the support 1a, and a foamable heat-sensitive adhesive layer is provided on the printed surface.
Examples of a include polypropylene film, polystyrene film and polyethylene terephthalate film, which are generally known or are in practical use. Of course, these films may be modified by copolymerization, blending, grafting or the like within a range in which the main body is maintained. Of course, synthetic paper, coated paper, etc. can be used as well. Among them, polypropylene film (hereinafter referred to as OPP film) is preferable from the viewpoint of easy separation from the container (difference in specific gravity), its incineration disposal, and the like.

Each of the above-mentioned films is basically transparent, and a non-heat-shrinkable stretched film obtained by biaxially stretching and heat setting is preferably used. This is the label 1 to which the present invention is directed.
Is similar to a pressure-sensitive adhesive label for printing, in which the both ends are superposed on each other and polymerized at both ends thereof, and heat is applied thereto through a heat-sensitive adhesive layer at that portion, and a heat seal or a solvent seal is generally used. This is because it is different from the shrink label sealed by. That is, the reason why the label 1 has heat shrinkability is that it tends to act in an unfavorable direction on this heat-sensitive adhesive label. However, non-heat shrinkage is not an absolute condition, and even if it has some heat shrinkability, it does not mean that it does not function as the label 1. Therefore, if necessary, there may be heat shrinkage within an allowable range. The obtained support 1 is provided with a printing layer (not shown) required as a product, but the printing layer is generally gravure printed using water-based ink (urethane-based or acrylic-based in many cases). Provided by. Of course, in the case of special images or small lots, screen printing is used, but this printing method is not limited.

On the upper surface of the printing layer, at least the heat-sensitive adhesive layer 4 of the polymerized portion 3 at both ends (the lower surface of the label end portion located above the portion 3) needs to be a foamable heat-sensitive adhesive layer. This is particularly because the adhesive force of the polymerized portion needs to be stronger (with a sufficient margin), which is achieved particularly by forming the foamable heat-sensitive adhesive layer. Since it is as described above, 4a of the polymerized portion at both ends is
The heat-sensitive adhesive layer corresponding to may be the same foamable heat-sensitive adhesive layer or the same non-foamable heat-sensitive adhesive layer.
That is, this is because the heat-sensitive adhesive layer 4a is a portion that is in direct contact with the container surface and does not have to be a foamable heat-sensitive adhesive layer that intentionally exhibits a stronger adhesive force. This is because when the label is picked up on the container, it is possible to perform positioning without dropping it and to have an adhesion force that allows easy removal. However, in the label of the present invention, the adhesion to the container surface of the heat-sensitive adhesive layer after being heat-foamed is considered to be the same as or slightly weaker than the adhesion by the conventional heat-sensitive adhesive layer and the ease of coating management, Since both layers should be formed with the same foamable heat-sensitive adhesive layer, both layers are used in the examples described later.

The material of the base of the heat-sensitive adhesive layer is a heat-sensitive adhesive (non-adhesive at room temperature) regardless of whether it is foamable or non-foamable. It is a thing. Basically, all of the commonly known heat-sensitive adhesives can be used with the same effect, so there is no particular limitation. That is, this heat-sensitive adhesive contains a thermoplastic resin that exhibits adhesiveness when heated as a main component, and as it is or contains a tackifier and / or a solid plasticizer. Here, in the case of containing the solid plasticizer, it is called a heat-sensitive delayed tack type adhesive, and is given a function (delayed tack property) of maintaining the adhesiveness for a certain period of time after the heat adhesiveness is expressed. Is.

Specific examples of the thermoplastic resin, tackifier and solid plasticizer are as follows.

First, as the thermoplastic resin, a vinyl acetate-based resin represented by vinyl acetate / ethylene copolymer,
Styrene resin represented by styrene / butadiene copolymer, acrylic resin represented by acrylic acid / ethylene copolymer, vinyl chloride resin represented by vinyl chloride / vinylidene chloride copolymer, rubber resin represented by polybutadiene, etc. is there. Among these resins, the resin having a softening point of about 80 to 130 ° C, preferably 90 to 115 ° C is good. Incidentally, these are generally handled as (aqueous) emulsion solutions.

On the other hand, as the tackifier, a terpene resin, an aliphatic or aromatic petroleum resin, a rosin resin,
Examples include phenol resins and coumarone / indene resins.

Examples of solid plasticizers include phthalic acid esters such as diphenyl phthalate, dibenzyl isophthalate and dihexyl phthalate, benzoic acid sucrose, tribenzoic acid glyceride, tetrabenzoic acid pentaerythritol and the like. Examples thereof include benzoic acid ester and tribenzyl trimellitate. These are all solid (crystal at room temperature).
The solid plasticizer is mainly used for imparting delayed tack property as described above, but for imparting appropriate plasticity (flexibility), for example, at room temperature such as dimethyl phthalate (diethyl). A liquid plasticizer may be used.

Since the heat-sensitive adhesive itself does not have sufficient (adhesion polymerization at both ends) adhesiveness in the present invention, particularly heat-expandable particles are contained, which is as follows. First, the thermal characteristics of the heat-expandable particles and the pressure-sensitive adhesive are desired to have the following correlation. That is, there is a temperature relationship in which the adhesive force begins to develop in the adhesive layer by heating, and the expandable particles start the foaming action by the heating. Therefore, even if there is a slight difference in both the temperatures, those that are in substantially the same temperature range are selected. Generally, the heat-sensitive adhesive to be used is determined, and the expandable particles are appropriately selected.

Specifically, it is divided into a chemical foaming agent which is decomposed by heating at a temperature of about 60 to 100 ° C. or a physicochemical foaming agent obtained by enclosing a volatile organic compound in a particulate thermoplastic resin. The chemical foaming agents include, for example, ammonium carbonate, diazoaminobenzene, azobisisobutyronitrile, etc., and mainly carbon dioxide gas and nitrogen gas are generated to foam. On the other hand, the physicochemical blowing agent is an organic compound having a particularly low boiling point (for example, about 100 ° C. or lower), for example, an aliphatic hydrocarbon such as n- or i-butane, n- or i-pentane, n-hexane and n-heptane, Halogenated aliphatic hydrocarbons such as trichlorofluoromethane have a softening point of about 130 ° C or less,
Preferably, a thermoplastic resin having a softening point similar to that of the thermoplastic resin as the main component of the heat-sensitive adhesive, for example, a chlorine-substituted vinyl resin such as polyvinyl chloride, polyvinylidene chloride, a copolymer of acrylonitrile and vinylidene chloride, or the like. , A styrene resin, an acrylic resin, an olefin resin, or the like. That is, this is in the microcapsule state in which the resin serves as the outer core and the organic compound is sealed therein. still,
From the viewpoints of adhesion, easiness of handling, etc., the microcapsules containing the aliphatic hydrocarbon are preferable.

When the chemical foaming agent and the physicochemical foaming agent are compared with each other, the latter is preferable, because it is easy to obtain a stronger adhesion force by the polymerization adhesion operation under heating and pressing. The physicochemical foaming agent has a larger foaming ratio, the roughness of the adhesive surface is finer, the heat-sensitive adhesive layer and the physicochemical foaming agent are composed of homogeneous components, foaming It is considered that due to the larger force from the inside due to the above, more strongly polymerized and adhered, and these act synergistically to show the effect. Therefore, it can be said that the pressure should be set lower than the pressure set with the non-foaming heat-sensitive adhesive.

The above-mentioned effect also greatly affects the content of the heat-expandable particles in the heat-sensitive adhesive, which is particularly 5 to 30% by weight (relative to solid content), preferably 8 to 27% by weight, further It is preferably maximized by including 12 to 23% by weight. That is, when the amount is less than 5% by weight, the expansion ratio is too small, and the adhesive surface does not have roughness and is smooth, so that sufficient adhesive force is not exhibited. It does not become so large, but it becomes smaller. Also, the surface of the adhesive layer becomes abnormally rough. It is considered that these factors are the reasons for alienating the effect of the foaming agent. Since the size of the expandable particles also affects the type of the foaming agent, the adhesiveness developing property, etc., it is better to check the selection sufficiently. For example, in the case of the physicochemical foaming agent, (Average particle size) It is preferable to keep it within about 10 to 100 μm.

The heat-sensitive adhesive label for a container of the present invention is constructed as described above, but the manufacturing means thereof is not limited, and the method is as follows. First, any one of the transparent non-shrink films described above is used as a support 1a (the thickness is generally about 50 to 100 μm in consideration of handleability as a label, etc.), and at least one surface thereof is degreased and washed. In some cases, surface treatment is further performed by an electrochemical means to improve wettability (adhesiveness). Then, a necessary pattern is gravure-printed on the treated surface using a water-based gravure ink. This printing is generally laid out so that the non-image portion is a solid pattern (for example, white) and the necessary pattern is printed on the image portion. Of course, in this layout, a pattern that can be applied to one container is set as a minimum unit, and multiple patterns can be taken. The thickness of the printing layer formed by this is generally about 2 to 6 μm.

Next, the foamable heat-sensitive adhesive is applied to the upper surface of the printed layer by, for example, the following three application patterns. (D) Whole surface coating, (E) Only both end surfaces are coated, (F) In addition to these both end surfaces, an appropriate pattern (stripe, grid, halftone dot, etc.) is additionally coated at the center. It is a pattern. First, in the case of the (D) pattern, the label is directly contacted with the entire side surface of the container after the container is rotated and both ends are polymerized and adhered (the label does not fall off but is easily peeled off).
In addition to being fixed by adhesion, it also provides heat insulation and cushioning. On the other hand, in the case of the (E) pattern, only the lowermost surface of the overlapped portions at both ends is in direct contact with the side surface of the container and is fixed so as not to fall off with a light adhesion force. And in the case of (F) pattern,
It is mounted in an intermediate state between the patterns of (D) and (E). In any case, since there is a bulging portion of the label due to foaming, if the cutting and peeling removal work after the end of use is performed at that portion, peeling will be easier.

The coating patterns of any of the above (D), (E) and (F) are generally continuously prepared by a gravure printing method using the prepared emulsion-shaped heat-foamable pressure-sensitive adhesive liquid. Coated and dried. In place of the gravure printing method, there is a case where it is desired to increase the coating thickness, or in the case of a small lot, the screen printing method is used. Among the coating patterns, particularly in the cases of (E) and (F), it is effective to continuously coat with the pattern shown in FIG. 2 (plan view), for example. If you cut the center of the coated surface,
This is because it is possible to immediately obtain a single label with both ends coated having the required width. Of course, from the cut to the rebound, polymerization adhesion,
It is easy to automate the process until taking out. In the figure, 5 is a roll-shaped support stock that has been printed (mandarin orange) and is cut in advance according to the container, and 6 is a foamable heat-sensitive adhesive layer of a predetermined width applied at a constant pitch. In other words, it corresponds to the width of (4 + 4a), which is the width required for close contact at both ends.
Here, the constant pitch is, when the center 7 of 6 is cut,
The cut label is pitched in the container, and both end surfaces are pitches where the adhesive layer (4 and 4a in FIG. 1) is polymerized. Therefore, this depends on the size of the container and what to do with the overlap width at both ends.

Regarding the coating thickness (thickness layer thickness after coating and drying) of the foamable heat-sensitive adhesive, at least the minimum thickness is necessary because the adhesion (adhesion) generally affects the thickness. Is. However, in the present invention, since it has foamability, it may be thinner than a general non-foaming heat-sensitive adhesive layer. That is, the adhesive layer is thickened by foaming, and the coating thickness can be reduced accordingly. This is also one of the features. Although it depends on the mixing condition of the heating foaming agent, generally, it is sufficient to apply it in an amount of about 3 to 10 μm.
This becomes about 1.3 to 1.7 times thicker, and supports a sufficient adhesion force expression.

The label is put into a container and polymerized at both ends,
This part is used by closely fixing it, but there are various attachment means. Here, the method of claims 5 and 6 which is preferably provided will be mainly described below. First, the container of interest is generally a rigid or semi-rigid container consisting of a barrel (circular, polygonal), a bottom and a mouth. Its material is mainly glass, metal,
It is plastic. The label of the present invention has a heat-sensitive adhesive layer,
Since it also has a heat-foaming property, it can be adhered with a smaller pressure, and also exhibits cushioning properties. Therefore, as provided in claim 4, it is more effective to use it in a semi-rigid container such as a PET bottle. It also becomes.

In the adding method, the following steps (A) to (C) are sequentially carried out. The step (A) carried out in the first first step is cut into the predetermined size (at least). The entire foamable heat-sensitive adhesive label (1) having the foamable heat-sensitive adhesive layers 4 and 4a on both ends is heated at a temperature equal to or lower than the foaming temperature of the heat-sensitive adhesive layer to develop the adhesive force. Here, the temperature at which the adhesive strength is expressed is preferably a temperature equal to or lower than the foaming temperature. The lower limit temperature is naturally determined because the lower limit temperature has a relationship with the effective adhesive force development temperature. More preferred is just the foaming temperature or a temperature as close as possible to this. When this is carried out at the foaming temperature, there is some foaming, and therefore, the adhesive layer is accompanied by some foaming when the adhesive strength is developed, which leads to further improvement of the adhesive strength in the subsequent double-sided polymerization adhesion. Because it will be. Here, a slight amount of foaming is about 40% or less of the whole, and if there is foaming larger than this, on the contrary, the adhesion force tends to decrease. Generally, the heating of the present label (1) is performed over the whole in terms of steps, but basically, only the adhesive layer portion is sufficient.
The hot air generator installed in the line will perform the whole or partial operation.

Then, in the second step (B), the tip of the label (1) exhibiting the adhesive force is attached to the side surface of the standby container to fix the position, and then the container is rotated and squeezed. While turning, polymerize so that the rear end becomes the upper surface. Therefore, the rotation is once stopped. Foamable heat-sensitive adhesive layer at the rear end (4)
Is in contact with the front surface of the (label) support (1a), and is in an adhesive / polymerized state with substantially no pressing force at this stage.

Then, in the third step (C), the pressure-sensitive adhesive / polymerized portion is heated while being positively pressed with a constant pressure at a temperature equal to or higher than the foaming temperature of the foamable heat-sensitive adhesive. Fix tightly. As a result, the polymerized portion is fixed with high adhesion (the adhesive strength changes to strength close to the adhesive strength), but the condition here is that the heating temperature must first be a temperature exceeding the foaming temperature. As a result, foaming occurs inside at once, resulting in a more adhesive state. It is considered that this is due to the effect that proper foaming is imparted to the adhered surface and the layer thickness is changed to a thicker layer by a single foaming. The heating temperature is set to a high temperature based on the foaming temperature of the heating foaming agent to be used, but if it is too high, the adhesive strength will decrease. It suffices to thoroughly check and decide in advance, but among the heating foaming agents exemplified above,
The foaming temperature is about 80 to 145 ° C, and the temperature may be about 5 to 20 ° C higher than this.

The heating is not limited to the above heating temperature, and it is preferable to heat while pressing. This is because both ends do not polymerize due to stronger adhesion when heated in a pressure released state. As for this pressing effect, the size of the generated bubbles, the expansion ratio (the internal amount of bubbles), etc. are appropriately controlled,
It is considered that it acts to develop stronger adhesion, but it is not certain. For the pressing, a method of positively pressing from the outside using a pressing member (for example, an elastic member) is adopted, but since internal pressure due to foaming is generated and added as an indirect pressing, it is not necessary to press too strongly. It should be pressed at least 0.3 × 10 ⁻⁵ Pa. The upper limit is 1 × 10 ⁻⁵ P because the adhesion does not increase even if it is pressed too strongly.
It can be up to a. The heating / pressing time must be at least the time required for the foaming to actually start and complete. This depends on the type of blowing agent used, but in the case of the physicochemical blowing agent, for example,
It takes about 3 to 10 seconds.

In the actual work, supply of the container,
Starting from the application of printing / heat-foaming pressure-sensitive adhesive to the support (1), cutting the label to a predetermined size, preheating for developing adhesive strength, supplying the container, sticking the container to the container, both ends The heating / pressing of the polymerized portion and the removal of the container are repeatedly performed in a series of automated systems. Nor does it specify the automation system.

[0035]

EXAMPLES The present invention will be described in more detail below with reference to comparative examples. The adhesive force shown in this example was measured as follows. In each of the attached labels in Example 3, the adhesive force with the PET bottle surface (hereinafter referred to as the bottle surface adhesive force) and the adhesive force between the polymerized layers (hereinafter referred to as the polymerized layer adhesive force) in a polymerized portion of 15 mm × 200 mm at both ends. Was measured by a peeling strength tester manufactured by Shinto Kagaku Co., Ltd., type HEIDON-17, and the strength was expressed as N / cm. The bottle surface adhesion was 90 degrees, and the polymerization interlayer adhesion was 180 degrees.
The peeling is performed at room temperature at a speed of 200 mm / min.

(Example 1) First, a heat-foamable pressure-sensitive adhesive was applied according to the following contents. ● Support film, one side degreased and washed, thickness 50μm, width 200mm, length 2
Figure 2 shows a 00m (non-shrinkable) biaxially stretched OPP film.
The mandarin orange picture shown in 1 was used as one pattern which was continuously printed at an equal pitch. ● Heat-foaming pressure-sensitive adhesive emulsion liquid containing 50% by weight of ethylene / vinyl acetate copolymer (the polymer has a melt index of 150 in which 25 mol% of vinyl acetate is bonded, no tackifier)
15% by weight (based on solid content) of a physicochemical foaming agent was added and mixed and dispersed. Here, as the foaming agent, i-butane is vinylidene chloride / acrylonitrile.
Matsumoto Yushi-Seiyaku Co., Ltd. Matsumoto Microsphere Series "F-30" (foaming temperature 80-85) microcapsulated with a copolymer (softening point 80-85 ° C).
C., the maximum expansion ratio is about 70%), and the particle size is 10 to 30 μm.

Then, the heat-foamable pressure-sensitive adhesive is applied to the support film in a non-coated length (in this case, orange picture) 180 m
m and coating length of 30 mm as one cycle pattern, repeated continuous coating was carried out by the gravure printing method, followed by drying for 60 seconds through a drying tunnel whose temperature was controlled at 60 ° C.
The coating thickness obtained here was 5 μm.

Comparative Example 1 In the heat-foamable pressure-sensitive adhesive used in Example 1, the mixing dispersion amount of the "F-30" foaming agent was set to 2% by weight, and the solid content concentration of ethylene / vinyl acetate copolymer was adjusted. This emulsion liquid was applied to an OPP film and dried under the same conditions except that the amount was changed to 60% by weight. The thickness of the foamable adhesive layer applied here is 5.3 μm
It was m.

Comparative Example 2 In the heat-foamable pressure-sensitive adhesive used in Example 1, the mixing dispersion amount of the "F-30" foaming agent was set to 37% by weight, and the solid content concentration of ethylene / vinyl acetate copolymer was adjusted. This emulsion solution was applied to an OPP film under the same conditions except that the amount was changed to 45% by weight.
Dried. The thickness of the foamable adhesive layer applied here is
It was 4.9 μm.

(Example 2) Using the same OPP supporting film as in Example 1, the following heat-foamable pressure-sensitive adhesive was coated under the same conditions as in the above example to provide a heat-foamable pressure-sensitive adhesive layer. . <Heat-foaming adhesive> To 200 parts of acrylic emulsion (ED910 manufactured by Dainippon Ink and Chemicals, Inc., solid content: 50% by weight), 10 parts of rosin ester emulsion (solid content: 50% by weight) was added and mixed, and this The same blowing agent "F-30" as in Example 1 was added to the above in an amount of 15% by weight (against both solid contents) and thoroughly mixed and dispersed. The pressure-sensitive adhesive layer formed as described above had a layer thickness of 4.8 μm.

(Example 3) First, in the long label obtained in each of the above examples, the center 15 mm of the heat-foamable adhesive layer portion (width 30 mm) was cut transversely, and the length having the adhesive layer at both ends 15 mm width was obtained. It was cut out into a label of 210 mm and a width of 200 mm. On the other hand, 12 PET bottles having a body circumference of 195 mm were prepared, and the label was subjected to the following procedure: polymerization, double-sided polymerization, and thermocompression bonding to complete the attachment.

That is, using the three labels cut out in each example, they are attached to three plastic bottles under the same conditions.
The conditions are as follows: First, put the label in a dryer controlled at 80 ° C., heat it for 30 seconds (with some foaming), take it out, immediately attach the heat-foamable adhesive layer portion at one end to the bottle, and while rotating, Polymerization was carried out with the adhesive layer portion at the end facing up. Then, a rubber sponge is brought into contact with the overlapped portion (width 15 mm) and pressed at 9 × 10 ⁻⁶ Pa, and 90 ° C. is applied to the portion.
Was heated by applying hot air for 8 seconds. The rubber sponge has a thickness of 10 mm, a width of 16 mm, and a length of 230 mm.
This was fixed to a T-shaped metal frame, and the whole was preheated to about 80 ° C. at the time of contact.

After the heating / pressing was completed, the temperature was cooled to room temperature, and the label was first checked. Since the 12 PET bottles were in the same state without any abnormality, this time, the non-adhesive layer portion (the orange picture portion) was cut off by cutting both sides while leaving the 15 mm width of the polymerized portion. Next, the label piece of the remaining polymerized portion is peeled from the bottle, but at the time of peeling, the adhesive force between the bottle surfaces is first measured, and then the label piece peeled from the bottle,
(Both ends) The adhesion between the polymerized layers was measured for each 3 samples,
This is summarized in Table 1 with the upper and lower limits. In the table, it can be seen that the adhesive strength between the bottle surfaces of the label is proper because it does not fall off during the operation and is easily peeled off upon separation. On the other hand, it can be seen that the adhesive force between the polymerized layers is extremely strong, and is improved to a level at which there is no danger of peeling during handling, more than ever before.

(Table 1)

[0045]

Since the present invention is constructed as described above, it has the following effects.

With both end polymerized portions having stronger adhesion strength,
It has become possible to obtain (print) heat-sensitive adhesive labels that can be attached to containers such as PET bottles. This eliminates the risk of falling off during handling, and makes it possible to handle with greater peace of mind than ever before.

Since it is possible to lower the pressure at the time of adhesion of both ends of the label by polymerization, it is possible to attach the label without worrying about denting, especially for semi-soft bottles such as PET bottles.

A label having a foamable heat-sensitive adhesive layer slightly foamed has a tackiness reduced to an appropriate state, so that it is necessary to intentionally add a tackiness improver (for example, an inorganic powder such as silica or calcium carbonate). do not do. It is effective for roll-rolling and pulling-out work without reducing the original adhesiveness.

Further, the label can be easily separated from the used container (raising due to foaming of the polymerized portions at both ends), and the collection can be carried out more quickly.

[Brief description of drawings]

FIG. 1 is a view exemplifying a cross section of a heat-sensitive adhesive label with a container and a polymerized portion at both ends.

FIG. 2 is a plan view showing an example of a coating pattern of a foamable heat-sensitive adhesive.

[Explanation of symbols]

1 ... Heat-sensitive adhesive label for containers 1a ... Support (film) 2 ... Container (cylindrical) 3 ... Both ends overlap 4, 4a ··· Foamable heat-sensitive adhesive layer 5 ... Supporting roll (roll) 6 ... Foamable heat-sensitive adhesive layer

Claims (6)

[Claims] 1. A container (2) is squeezed to polymerize both end portions, and the polymerized portion (3) is pressed and heated by a heat-sensitive adhesive layer (4, 4a) provided on the lower surface of both end portions and added. In the heat-sensitive label (1) for a container to be mounted, the heat-sensitive adhesive layer (4) provided on at least the lower surface of the label end portion located above the polymerized portions (3) at both ends, comprises the heat-foamable fine particles 5 ~ 3
A heat-sensitive adhesive label for containers, comprising a foamable heat-sensitive adhesive containing 0% by weight. 2. A component forming the heat-sensitive adhesive layer (4, 4a) is mainly composed of a thermoplastic resin having a softening point of 80 to 130 ° C., and the heat-foamable fine particles have a boiling point of 100 ° C.
The heat-sensitive adhesive label for containers according to claim 1, comprising the following expandable thermoplastic resin particles containing saturated hydrocarbon. 3. The heat-sensitive adhesive property for a container according to claim 1, wherein the support (1a) of the heat-sensitive label for a container is a non-shrinkable polypropylene film, polyethylene terephthalate film or polystyrene film. label. ， 4. The heat-sensitive adhesive label for a container according to claim 1, wherein the container is a polygonal or cylindrical plastic semi-rigid container. 5. The method for adding a heat-sensitive adhesive label for a container according to claim 1, wherein the following steps (A) to (C) are sequentially performed. . (A) A first step in which the whole heat-sensitive adhesive label (1) for containers cut into a predetermined size is heated at a temperature equal to or lower than the foaming temperature of the foamable heat-sensitive adhesive to develop an adhesive force, (B) And a second step of sticking the tip of the label (1) exhibiting the adhesive force to the side surface of the container, and rotating the container to rotate while superimposing so that the rear end becomes the upper surface. And a third step of heating the polymerized portion while pressing it at a temperature higher than the foaming temperature of the foamable heat-sensitive adhesive, thereby fixing the polymerized portion in close contact. 6. The pressing in the third step of (C) above,
0.3-1.0 x 10 ^-5Pa is according to claim 5.
Attaching method of heat-sensitive adhesive label for container.