JP2005281561A - Adhesive film and labels using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive film in which an end of an adhesive film is lifted off from an adherend by heating the adhesive film attached to the adherend and can be easily peeled off. Moreover, the labels using the adhesive film which solves the said objective are provided.
A pressure-sensitive adhesive film in which a resin film a and a resin film b having different heat shrinkage rates are laminated, and a pressure-sensitive adhesive layer c is laminated on the surface of the resin film b, at 40 to 110 ° C. A pressure-sensitive adhesive film in which the relationship between the thermal shrinkage rate j of the resin film a and the thermal shrinkage rate k of the resin film b is j> k is used.
[Selection] Figure 1

Description

  The present invention relates to a pressure-sensitive adhesive film used for a label or a sticker, and more particularly to a pressure-sensitive adhesive film excellent in peeling workability when a label or a sticker is attached to an adherend and then the label is peeled off from the adherend.

  Re-adhesive film is intended to be attached to vehicles such as vending machines, automatic ticket gates, trains, buses, etc., for the purpose of advertising products and services. is there. For example, plastic containers are used when food manufacturers or wholesalers ship foods to supermarkets, etc., and adhesive labels that display information such as destinations, product names, and quantities as bar codes are affixed to these containers. The person who receives the container performs a sorting operation based on the information displayed on the adhesive label. Thus, the adhesive label is also used as a display material for business communication. The container to which the adhesive label is attached is used repeatedly. At that time, the used adhesive label is peeled off, and an adhesive label on which new information is displayed is attached.

  As described above, pressure-sensitive adhesive films that are supposed to be peeled off after a certain period of use are used in the form of labels, stickers, and the like over a wide range from commercial or business use to household use.

  As the re-peelable pressure-sensitive adhesive film based on the premise of peeling, generally, a film that suppresses the adhesive force of the pressure-sensitive adhesive as much as possible and facilitates the peeling work is widely used. However, such a pressure-sensitive adhesive film has an adhesive force that is too weak and may be peeled off spontaneously, or may be peeled off by contact with a person or an object. Depending on the application, a certain degree of adhesive force may be required, and such a pressure-sensitive adhesive film has poor removability and is difficult to perform a peeling operation.

  A technique for maintaining a necessary adhesive force during use and easily peeling after use is disclosed (see Patent Document 1). The technology relates to a pressure-sensitive adhesive label provided with a pressure-sensitive adhesive layer on the back surface of a plastic film that shrinks by heat, and the pressure-sensitive adhesive label shrinks when applied with hot water after use and peels off from the adherend. is there. However, when the pressure-sensitive adhesive label using the technique is actually shrunk by heating, the entire pressure-sensitive adhesive label is shrunk while being in close contact with the surface of the adherend. In the end, it sometimes occurred that the tip of a nail, a cutter knife or the like had to be peeled off by a member on a thin plate with a sharp tip. In addition, when the pressure-sensitive adhesive label was severely contracted, the pressure-sensitive adhesive easily peeled off from the heat-shrinkable film and remained on the surface of the adherend.

  Further, there has been proposed one in which the four corners of the label float when attached to a delivery container and exposed to a low temperature (see Patent Document 2). The technology is such that the label floats off during use while the container is actually kept cold, so that the floating end of the label comes into contact with another object during use or transportation, There is a problem that dust adheres to the pressure-sensitive adhesive layer on which the label is lifted and the beauty is apt to occur and a problem in terms of hygiene is likely to occur.

  In addition, a label that can be easily peeled off when applied in warm water by a combination of a heat-shrinkable film and an adhesive containing an absorbent polymer has been proposed (see Patent Document 3). Since this technology utilizes the fact that the adhesive strength decreases due to water absorption of the pressure-sensitive adhesive, the pressure-sensitive adhesive layer is also detached from the heat-shrinkable film, and there are various types of pressure-sensitive adhesive layers that are detached during wastewater treatment. There is a problem in that it is difficult to recover due to adhesion to the object.

JP 08-248887 JP 08-26984 A JP 05-173487 A

  Therefore, the object of the present invention is to heat the pressure-sensitive adhesive film adhered to the adherend so that the end of the pressure-sensitive adhesive film is lifted off from the adherend and can be easily peeled off. Is to provide. Moreover, the other objective of this invention is to provide the labels using the adhesive film which solves the said objective.

  As a result of intensive studies, the present inventors have found that the above problems can be solved by using an adhesive film having the following constitution. That is, the present invention is a pressure-sensitive adhesive film in which a resin film a and a resin film b having different heat shrinkage rates are laminated, and a pressure-sensitive adhesive layer c is laminated on the surface of the resin film b. The adhesive film in which the relationship between the thermal shrinkage rate j of the resin film a and the thermal shrinkage rate k of the resin film b is j> k is provided. Moreover, this invention provides the labels using said adhesive film.

  The pressure-sensitive adhesive film of the present invention has a structure in which a resin film a, a resin film b, and a pressure-sensitive adhesive layer c are laminated in this order. Furthermore, the relationship between the thermal shrinkage rate j of the resin film a and the thermal shrinkage rate k of the resin film b at 40 to 110 ° C. is j> k. Therefore, when the adhesive film of the present invention is attached to an adherend and then heated with hot air or warm water, the resin film a constituting the surface layer portion of the adhesive film is further contracted. Then, the adhesive film curls due to the difference in shrinkage between the resin film b and the resin film a, and the end of the adhesive film is lifted from the adherend surface of the adherend and peeled off. In particular, when a resin film that contracts particularly greatly in one direction is used as the resin film a, and a combination of the resin film a and the resin film b is selected as the resin film b so that the stiffness (waist) is low and j >> k. The label is peeled off from the end. Therefore, in order to peel off the adhesive film from which the edge has been peeled off from the adherend, it is only necessary to pick up and lift off the raised edge or the rolled-up and rounded portion of the cylinder. Can do.

  Hereinafter, the adhesive film according to the present invention will be specifically described. In this specification, a pressure-sensitive adhesive sheet having a display function in which a layer of a pressure-sensitive adhesive is provided on one side of the base material and further printed on the opposite surface of the base material and processed into a desired shape is generically named. This is called “labels”. Labels include labels, stickers, eye catch labels, and the like. In addition, simply “label” means “labels”.

  The pressure-sensitive adhesive film of the present invention has a structure in which a resin film a, a resin film b, and a pressure-sensitive adhesive layer c are laminated in this order, but an adhesive layer e is laminated between the resin film a and the resin film b. The release liner d may be laminated on the pressure-sensitive adhesive layer c. An example in which the adhesive layer e and the release liner d are laminated is shown in FIG.

  The resin film a is not particularly limited as long as the thermal shrinkage rate at 40 to 110 ° C. is larger than that of the resin film b, but the shrinkage start temperature is preferably 70 to 110 ° C. The resin film a may be a biaxially stretched film or a uniaxially stretched film. In the pressure-sensitive adhesive film of the present invention using a biaxially stretched film, the biaxially stretched film shrinks in two directions by heating, so that the entire periphery of the pressure-sensitive adhesive film comes to float from the adherend. In addition, when a uniaxially stretched film is used, it contracts in one direction by heating, so that only the end portion in the contraction direction floats or rolls up from the adherend.

  Further, the front and back of the resin film a may be subjected to corona treatment or may be subjected to anchor coat treatment for the purpose of improving ink adhesion. Furthermore, when using as a label, you may provide the printing layer h2 on an anchor coat process layer. An example using a resin film a having a printed layer h2 formed on the surface is shown in FIG.

  The shrinkage rate of the resin film a only needs to be slightly higher than the shrinkage rate of the resin film b used in combination, but the shrinkage rate during shrinkage of the resin film a used in the present invention is 1 to 70%. preferable. Among them, the shrinkage rate is more preferably 5 to 70%, and particularly preferably 45 to 70%.

  As the resin film a used in the present invention, a film made of a known thermoplastic resin can be used. For example, polyethylene, polypropylene, polyester, ethylene vinyl acetate copolymer, polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, polybutylene succinate carbonate, polyvinyl chloride with an appropriate amount of plasticizer, polystyrene (GPPS), Examples thereof include impact-resistant polystyrene (HIPS) obtained by graft-polymerizing styrene to rubber. Among these resins, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, and polybutylene succinate carbonate are preferably used. More preferably, linear low density polyethylene (LLDPE), polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, and polybutylene succinate carbonate are mentioned. Further, the above-mentioned resin having a melting point in the range of 90 ° C. to 110 ° C., or a resin composition adjusted and blended so that the melting point is in the range of 90 ° C. to 110 ° C. is most preferable. The thermoplastic resin used for the adjustment is not particularly limited, and for example, an appropriate amount of high density polyethylene may be blended. Examples of commercially available polyethylene succinate resins include “Luminale SE” manufactured by Nippon Shokubai Co., Ltd., “Bionole” manufactured by Showa Polymer Co., Ltd., “Yupec” manufactured by Mitsubishi Gas Chemical Co., Ltd., etc. as polybutylene succinate resins.

  Various additives such as pigments, fillers such as calcium carbonate and silica, dyes, UV absorbers, heat stabilizers, antioxidants, plasticizers, antistatic agents, lubricants may be added to the resin. Good.

  Resin film a melts a thermoplastic resin and continuously extrudes it using a T die, a circular die, etc., and then rapidly cools to produce an original fabric, which is then reheated, and rolled longitudinally. Stretch continuously with a machine. The draw ratio in this case is 3 to 10 times, more preferably 4 to 6 times. At this time, the thickness of the resin film a is preferably 20 μm to 200 μm, more preferably 20 μm to 80 μm, and even more preferably 40 μm to 70 μm. When the thickness is within this range, the label has sufficient rigidity, and it becomes easy to automatically stick the pressure-sensitive adhesive label produced using the pressure-sensitive adhesive film of the present invention to containers using an auto labeler. If this range is exceeded, the balance of rigidity with the resin film b is lost, the film shrinks while wavy and does not curl into a smooth arc, and the adhesive may peel off the adhesive film and remain on the adherend. is there.

  The resin film b is not particularly limited as long as the shrinkage rate is lower than that of the resin film a used in combination, but the difference in shrinkage rate at a heating temperature of 40 to 110 ° C. is 1% or more. It is preferable that it is 5% or more. In particular, the resin film b is preferably one that hardly causes heat shrinkage (heat shrinkage rate of 1% or less). If it is such a film, the resin film a laminated on the resin film b does not shrink extremely, and the film does not shrink while undulating. Therefore, the pressure-sensitive adhesive layer c does not peel off from the pressure-sensitive adhesive film and does not fall off, and the pressure-sensitive adhesive does not remain on the adherend. Examples of the resin film b include polyester, polypropylene (OPP), polycarbonate, polyimide, and the like. A polyester film is preferred from the viewpoints of heat shrinkability, rigidity and economy. As thickness, 16-100 micrometers is preferable, 16-75 micrometers is preferable, and 25-50 micrometers is more preferable. If the thickness is 16 μm or less, the rigidity of the film decreases and the auto labeler suitability decreases. Further, the rigidity is too low for the shrinkage of the resin film a, and the film shrinks while undulating. If it exceeds 100 μm, the stiffness is too high and the film curls in an arc to prevent the film from rising from the end of the film.

  Even if the surface of the resin film b is treated with a corona treatment or an anchor coating agent, there is no problem. Various additives such as various pigments, fillers such as calcium carbonate and silica, dyes, ultraviolet absorbers, heat stabilizers, antioxidants, plasticizers, antistatic agents, lubricants, etc. are used in the resin used for the film. It may be added. Furthermore, when using as a label, you may provide the printing layer h1 on an anchor coat process layer. An example using the resin film b having the printed layer h1 formed on the surface is shown in FIG.

  The pressure-sensitive adhesive layer c has an adhesive strength to various adherends based on JIS Z 0237 (2000 version) of 1.0 to 15 N / 25 mm, an elongation at break of 500 to 1500%, and a constant load peel test. It is preferable that the peeling distance in is 25 mm or more. The adhesive force is more preferably 3.0 to 10.0 N / 25 mm. When the label is in the above range, the label is stuck to the adherend, and the label does not fall off even after a long time, and the adhesive force is too strong, and the resin film a shrinks due to heating. However, the adhesive film does not stop peeling.

  When the elongation at break of the pressure-sensitive adhesive layer c is 500% or less, the pressure-sensitive adhesive is too hard to obtain a sufficient adhesive force, and when it is 1500% or more, the pressure-sensitive adhesive at the time of raising the blank portion caused by the punching of the label The stringing becomes larger and the processability becomes worse. When the peel distance in the constant load peel test is 25 mm or less, strong adhesiveness is obtained and re-peelability is impaired, and the pressure-sensitive adhesive layer tends to remain on the adherend side at the time of peeling, making it difficult to achieve the effects of the present invention.

  Although it does not specifically limit as an adhesive, For example, it can select and use suitably from an acrylic resin adhesive, a urethane resin adhesive, a rubber adhesive silicone resin adhesive, etc., for example. Among these, an acrylic resin-based pressure-sensitive adhesive is preferable. Examples of the form of the pressure-sensitive adhesive include solvent-based and water-based emulsions. If you select a water-based emulsion and select a method of immersing in warm water as the heating method, the warm water will penetrate into the pressure-sensitive adhesive layer and the adhesive force will decrease, making it easier to peel off. There may be a problem of detachment.

The application amount of the pressure-sensitive adhesive is preferably in the range of 10 to 30 g / m ² by dry weight. If it is less than 10 g / m ² , the adhesive strength is reduced, making it difficult to fix the adhesive film in place, and if it exceeds 30 g / m ² , the adhesive protrudes from the adhesive film, contaminates the surroundings, When processing, there is a possibility that the margin raising property may be lowered and the auto labeler suitability may be lowered.

  Manufacture of an adhesive film is performed by well-known methods, such as a transfer method. The pressure-sensitive adhesive coating apparatus may be a generally known coating method such as a comma coater, knife coater, gravure coater, roll coater or the like. A pressure-sensitive adhesive adjusted to a solid content of 20 to 60% by mass with a coating apparatus is applied to a release liner.

  In order to process the pressure-sensitive adhesive film of the present invention into a label or sticker state, a release liner d may be bonded to the pressure-sensitive adhesive layer c. The release liner d is not particularly limited as long as it is subjected to a release treatment, and a known one can be used. For example, a material suitably selected from polyethylene laminated paper, glassine paper, clay coated paper, polyester film, polypropylene film and the like and formed with a release layer of a silicone compound can be suitably used. As a method of forming an adhesive layer on the adhesive film of the present invention, a method in which an adhesive coated on a release liner and dried with hot air is bonded to the surface of the resin film b of the laminate of the resin film b and the resin film a. It is preferable to use it. On the other hand, the method of directly applying the adhesive to the laminate of the resin film b and the resin film a is not suitable for producing the adhesive film of the present invention because shrinkage occurs in a drying furnace.

  The lamination method of the resin film a and the resin film b is not particularly limited as long as the resin film a and the resin film b have a strength that does not easily peel even when heated at 40 to 110 ° C. Can be used. As a known method, for example, there is a method of providing an adhesive layer e. A known pressure-sensitive adhesive or an adhesive for dry lamination can be used for the adhesive layer e. Further, a method of forming a film by extruding two layers with a T-die extrusion equipment or the like can be employed. A film formed by the calendering method may be heat-sealed at a high temperature and pressure.

  In the case of peeling after the adhesive film of the present invention is applied to the adherend, for example, a method of blowing hot air of 70 ° C. or higher to the adherend to which the adhesive film is attached, in warm water of 70 ° C. or higher or other heat medium The method of immersing, the method of irradiating infrared rays with an infrared lamp, etc. are mentioned. Further, when an emulsion-based adhesive is used and the adhesive contains moisture, it can be heated by a high-frequency device.

Although it demonstrates concretely by an Example below, it is not limited to these. In addition, unless otherwise indicated, "part" and "%" show a mass reference | standard.
1) Production of resin film a (uniaxially stretched polyethylene film)
Pellets of LLDPE trade name “NUCG-5472” manufactured by Nippon Unicar Co., Ltd. are supplied to an extruder, melted at 300 ° C., continuously extruded by a T-die, and rapidly cooled to produce a 120 μm original film. The film was reheated to 60 ° C. and stretched 3 times in the flow direction by a roll type vertical stretching machine to obtain a heat-shrinkable uniaxially stretched film a11 having a thickness of 40 μm.

  Polybutylene succinate adipate resin “Bionore # 3100” manufactured by Showa Polymer Co., Ltd. and polybutylene succinate “Bionore # 1001” were mixed at a mass ratio of 5: 1, supplied by an extruder, melted to 190 ° C., and circular. The original film having a thickness of 240 μm was prepared by continuously extruding with a die and quenching. It was reheated to 70 ° C. and stretched 4 times in the flow (MD) direction by a roll type vertical stretching machine to obtain a resin film a21 having a thickness of 60 μm.

  Further, a uniaxially stretched polyester film “PTR47” manufactured by C.I. Kasei Co., Ltd. having a thickness of 45 μm is defined as (a31).

Table 1 shows the physical properties of each resin film a.

In Table 1, each measuring method is as follows.
<Measurement of thickness>
In an environment of 23 ° C. and 50% RH, measurement was performed by the method (Method A) defined in JIS K7130. Using a thickness meter (film thickness tester “TH-102” manufactured by Tester Sangyo Co., Ltd.), 10 points were measured at equal intervals in the width direction, and the average value was obtained.
<Measurement of heating shrinkage>
Test specimens of 50 mm are prepared in both the width direction and the flow direction.
The test piece is immersed in warm water at each temperature of 90 ° C. for 10 seconds, and the shrinkage rate is obtained by the following formula. Here, a positive value indicates contraction, and a negative value indicates extension.
Shrinkage rate (%) = {(50 mm−length after immersion) / 50 mm} × 100

2) Preparation of anchor coating agent 7 parts of synthetic silica “Silycia 350” manufactured by Fuji Syria Chemical Co., Ltd. as a pigment that absorbs ink, 30 parts of acrylic resin “Thermolac EF-32” manufactured by Soken Chemical Co., Ltd. as a binder resin, dispersion medium A total of 100 parts of a mixed solution of 63 parts of a mixed solvent of ethanol and isopropyl alcohol 4: 1 was prepared. Using a paint conditioner, the blended solution was stirred for 20 minutes to obtain an anchor coating agent having a solid content of 23%.

3) Preparation of laminated film (for printing) <Preparation of dry laminate adhesive e1>
90 parts by mass of an adhesive main agent (Dainippon Ink Chemical Co., Ltd., Dick Dry LX-605) and 10 parts by mass of a curing agent (Dainippon Ink Chemical Co., Ltd., trade name: KW75) are blended in 10 parts by mass of ethyl acetate. A dry laminate adhesive e1 was prepared by diluting and stirring well.
<Preparation of laminated film>
After corona treatment is performed on both surfaces of a resin film a11 having a thickness of 40 μm, the anchor coat agent is coated at a low temperature of 40 ° C. or lower so that the coating amount after drying is 1.5 g / m ² using a gravure coater. The resin film a (a12) was obtained by drying (for printing). Next, as a resin film b11, a polyester film “Lumirror T60 # 38” manufactured by Toray Industries, Inc. is adjusted so that the coating amount after drying the dry laminating adhesive e1 is 4.0 g / m ² and adjusted to 1 at 80 ° C. After drying for a minute, after cooling to room temperature to 40 ° C or lower (less than 70 ° C is acceptable), it is bonded to the heat-shrinkable adhesive film a11 and cured at 40 ° C for 7 days (for printing). f11 was obtained. Hereinafter, it is simply referred to as a laminated film.
A resin film a (a22) and a laminated film f21 (for printing) were obtained in the same manner except that the resin film a21 was used instead of the resin film a11.
A resin film a (a32) and a laminated film f31 (for printing) were obtained in the same manner except that the resin film a31 was used instead of the resin film a11.

4) Preparation and coating of pressure-sensitive adhesive <Preparation of acrylic copolymer>
In a reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel, and a nitrogen gas inlet, 100 parts by mass of the monomer mixture blended in the combination of Table 2 and 2,2′-azobis as a polymerization initiator 0.2 part by mass of isobutylnitrile was dissolved in 100 parts by mass of ethyl acetate and polymerized at 80 ° C. for 8 hours to obtain a solution of acrylic copolymers c1 to c3.

In addition, the meaning of the abbreviation of the monomer used in Table 2 is as follows.
2EHA: 2-ethylhexyl acrylate BA: n-butyl acrylate MA: methyl acrylate VA: vinyl acetate AA: acrylic acid HEA: 2-hydroxyethyl acrylate

<Preparation of adhesive main agent solutions c1 to c4>
The adhesive main ingredient c1 of Table 2 was made into the solution of the adhesive main ingredient of 30% of solid content by mixing toluene with 100 mass parts of acrylic copolymers.
The adhesive main agent c2 in Table 2 was prepared as a solution of an adhesive main agent having a solid content of 30% by mixing toluene with 100 parts by mass of the acrylic copolymer. 20 parts by mass of a tackifier resin (hydrogenated petroleum resin Alcon M-100 manufactured by Arakawa Chemical Co., Ltd.) was added to parts by mass, and toluene was further mixed to prepare a solution of an adhesive main agent having a solid content of 50%. .
The adhesive main agent c4 in Table 2 is prepared by adding 20 parts by mass of a tackifier resin (rosin ester resin superester A-100 manufactured by Arakawa Chemical Co., Ltd.) to 100 parts by mass of an acrylic copolymer, and further mixing toluene. Thus, a pressure-sensitive adhesive main agent solution having a solid content of 45% was obtained.

5) Measurement of adhesive adhesive strength, elongation at break and peel force at constant load
<Measurement of adhesive elongation at break>
-Preparation of measurement sample Each pressure-sensitive adhesive in Table 3 was applied to Oji Paper's release liner OKB-105NC so that the thickness after drying was 20 µm, and dried at 90 ° C for 3 minutes using a hot air dryer. After aging at 23 ° C. for 14 days, an adhesive was laminated to obtain a measurement sample having a thickness of 400 μm.
Measurement method In an environment of 23 ° C. and 50% RH, a pulling speed of 300 mm / min. Measured with
A Tensilon universal testing machine “RTA-100” manufactured by A & D was used as a measuring machine.
<Measurement of adhesive strength>
In accordance with JIS Z0237 (2000 version), the sample and the adherend are cured for 3 hours or more in an environment of 23 ° C. and 50% RH. A flat plate made of a smooth polypropylene resin was used for the adherend. The sample size is 25 mm wide in the width direction and about 100 mm long in the flow direction, and a pulling speed of 300 mm / min. And peeled in the 180 ° direction, and the stress at that time was measured. A Tensilon universal testing machine “RTA-100” manufactured by A & D was used as a measuring machine. As test samples, Comparative Examples 1, 2, and 3 were used to measure the adhesive strength of each pressure-sensitive adhesive.
<Constant load peeling evaluation method>
In an environment of 23 ° C. and 50% RH, a size-adhesive sample having a width of 25 mm × 50 mm is stuck on a flat plate made of polypropylene resin, reciprocated with a 2 kg roller, and left to stand for one hour. A weight of 100 g is applied to one end of the short side of the attached adhesive sample in the direction of gravity.
At this time, the adhered adhesive sample and the adherend are fixed so as to be at an angle (horizontal) of 90 ° with respect to the direction of gravity. Measure the peeled distance of the adhesive sample one hour after applying the weight. When it peels within 1 hour, it describes as 50 mm.

  Table 4 shows the measurement results.

(Example 1)
0.3 parts by mass of an isocyanate-based crosslinking agent (trade name: Coronate L-45, manufactured by Nippon Polyurethane Industry Co., Ltd.) is added (c11) to 100 parts by mass of the adhesive main agent c1 solution, and then dried. It is applied to release paper (Separate 64GPS (M) Asagi, manufactured by Oji Paper Co., Ltd.) that has been subjected to a release treatment so that the subsequent coating thickness is between 22 and 28 g / m ² , and dried at 80 ° C. for 2 minutes. As a result, a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive c11 was formed and bonded to the already produced laminated film f11 to obtain a laminated pressure-sensitive adhesive film g11.

(Example 2)
In Example 1, 0.8 parts by mass of an aluminum acetylacetonate-based cross-linking agent (M5A manufactured by Soken Chemical Co., Ltd.) was blended with the adhesive main agent c2100 parts by mass using the laminated film f21. A laminated adhesive film g21 was obtained in exactly the same manner except that the material (c21) was used.

(Example 3)
In Example 2, using the laminated film f31, 2.5 parts by mass of an isocyanate-based crosslinking agent (trade name: Coronate L-45, manufactured by Nippon Polyurethane Industry Co., Ltd.) with respect to 100 parts by mass of the adhesive main agent c3. A laminated adhesive film g31 was obtained in the same manner except for the addition of part (c31).

(Comparative Example 1)
The adjusted adhesive c31 is applied to a release paper (Separate 64GPS (M) Asagi, manufactured by Oji Paper Co., Ltd.) that has been subjected to a release treatment so that the coating thickness after drying is between 22 and 28 g / m ^2. , Dried at 80 ° C. for 2 minutes, and bonded to (printing) resin film a (a12) to obtain an adhesive film.

<Heat peelability test>
Prepare 10 samples each cut out of 25 mm (TD direction) × 50 mm (MD direction) from each sample of the above examples and comparative examples, and apply them to a smooth polypropylene resin plate in an environment of 23 ° C. × 50%. I left it for a week. Thereafter, each sample was immersed in warm water of 98 ° C. for 30 seconds, and the state of peeling was observed. The evaluation criteria are described below.
(Double-circle): It peels and falls from a to-be-adhered body within 30 second, and there is no contamination (glue residue) with respect to a to-be-adhered body.
○: After 30 seconds, the test piece curls and floats from the adherend but does not detach, and there is no contamination (glue residue) on the adherend.
X: Partially peeled off after 30 seconds and floated, but did not fall off from the adherend, and a part of the lifted part was contaminated with adhesive (residue residue).
As a result of the test, the corresponding number was counted.

  The above test results are shown in Table 6.

  In Examples 1 to 3, when heated as shown in Table 6, when the sample is heated, it naturally peels or desorbs from the adherend and does not contaminate the adherend. In Comparative Example 1, although the film itself shrinks, it is difficult to remove from the adherend and the probability of contaminating the adherend is high.

It is a schematic sectional drawing of the adhesive film of this invention which has the contact bonding layer e and the release liner d. It is a schematic sectional drawing of the adhesive film of this invention which formed the printing layer h1 on the surface of the heat shrink film b. It is a schematic sectional drawing of the adhesive film of this invention which formed the printing layer h2 on the surface of the resin film a.

Explanation of symbols

1 Resin film a
2 Resin film b
3 Adhesive layer c
4 Release liner d
5 Adhesive layer e
6 Print layer h1
7 Print layer h2

Claims (7)

A resin film a and a resin film b having different heat shrinkage rates are laminated, and further an adhesive film c is laminated on the surface of the resin film b, and the resin film at 40 to 110 ° C. A pressure-sensitive adhesive film in which the relationship between the thermal shrinkage rate j of a and the thermal shrinkage rate k of the resin film b is j> k. 2. The pressure-sensitive adhesive film according to claim 1, wherein the resin film a has a heat shrinkage ratio j of 1 to 70% at 40 to 110 ° C. 3. The pressure-sensitive adhesive film according to claim 1, wherein the resin film a has a thickness of 20 μm to 200 μm. The pressure-sensitive adhesive film according to claim 1, further comprising an adhesive layer e between the resin film b and the resin film a. The adhesive strength of the pressure-sensitive adhesive layer c in JIS Z0237 (2000 version) is 1.0 to 15 N / 25 mm, and the elongation at break in a tensile strength test is 500 to 1500%. Or the adhesive film in any one of 4. The pressure-sensitive adhesive film according to any one of claims 1, 2, 3, 4 and 5, wherein a peel distance in a constant load peel test is 25 mm or more. Labels using the adhesive film according to any one of claims 1, 2, 3, 4, 5 and 6.

Images