JP6461769B2 - label - Google Patents

Description

  The present invention relates to a label attached to an article or the like in a low temperature environment.

  In a medical facility such as a hospital or a research facility such as natural science, in order to preserve specimens such as biological tissues and cells for a long period of time, the specimens are stored in a container and immersed in liquid nitrogen (-196 ° C) to be inert. In order to identify specimens that are stored for a long period of time in a cryogenic freezer that can be frozen at −80 ° C. By attaching a label on which sample identification information and the like are attached, sample identification management can be performed for each container based on the label identification information and the like.

  An example of such a label is a label disclosed in Patent Document 1. The label of Patent Document 1 includes a polyester film (base material) and an adhesive layer (adhesive part) applied to one surface of the polyester film, and the adhesive layer is attached to an article such as a container. Is. Specifically, the pressure-sensitive adhesive layer is composed of an acrylic pressure-sensitive adhesive, a tackifier, and a polyisocyanate-based crosslinking agent, and is crosslinked by the polyisocyanate-based crosslinking agent, thereby improving the elasticity of the pressure-sensitive adhesive layer. It is structurally stable.

JP 10-195394 A (page 6)

  In general, when a container with a label attached is stored frozen in a low-temperature environment, the container and the label thermally expand / contract as the temperature changes during freezing and thawing. Since the base material, adhesive part, and container of the label have different physical properties, the base material, adhesive part, and container have different thermal expansion coefficients, and the difference in the thermal expansion coefficient causes a difference in dimensional change between the container and the base material. Occurs. At this time, an external force acts on one surface of the adhesive portion in contact with the container and the other surface of the adhesive portion in contact with the base material, whereby the adhesive portion is deformed to deform the container and the base material. Try to follow the movement of the. However, in the pressure-sensitive adhesive sheet as in Patent Document 1, crosslinking is performed by adding a polyisocyanate-based crosslinking agent to the pressure-sensitive adhesive layer coating solution, and the elasticity of the pressure-sensitive adhesive layer is increased. Due to the deformation of the pressure-sensitive adhesive layer, the elastic restoring force to return to the shape before the deformation increases, the deformation of the pressure-sensitive adhesive layer is suppressed, and the container and the polyester film adhere to the dimensional deformation due to thermal expansion / contraction. There was a possibility that the adhesive layer could not sufficiently follow, the distortion of the adhesive sheet (polyester film and adhesive layer) was increased, and the adhesive sheet was peeled off from the container.

  The present invention has been made paying attention to such problems, and it is possible to maintain a sticking state to a container at the time of freezing and thawing, and to provide an optimum label for use in a low temperature environment. To do.

In order to solve the above problems, the label of the present invention is:
A label having a sheet-like base material and an adhesive part formed on at least one surface of the base material, and used by being attached to a container in a low-temperature environment,
The adhesive part is characterized by comprising natural rubber or isoprene rubber as a main component and having a sulfur content of 0 to 0.1% by mass.
According to this feature, the adhesive portion is mainly composed of natural rubber or isoprene rubber, and therefore has excellent elongation properties, and the content of sulfur bonding between molecules of natural rubber or isoprene rubber is 0 to 0.1 mass. Therefore, even if the natural rubber or isoprene rubber molecules are bonded to each other through sulfur, the physical properties of the natural rubber or isoprene rubber are retained. The adhesive part can easily follow the thermal expansion / contraction of the material, the adhesive part can be made difficult to peel from the container, and a label suitable for use in a low temperature environment can be obtained.

A thermal expansion coefficient of the base material is substantially the same as a thermal expansion coefficient of the container.
According to this feature, the thermal expansion coefficient of the base material is substantially the same as the thermal expansion coefficient of the container, and the thermal expansion / contraction of the container and the base material during freezing and thawing can be made substantially uniform. The possibility that the external force acting on the part does not concentrate on the specific part and the adhesive part peels from the container can be further reduced.

The substrate is made of a single layer material.
According to this feature, it is composed of a single-layer material, and the entire base material is thermally expanded / contracted substantially uniformly during freezing and thawing, allowing the adhesive part to follow. Can be suppressed.

The state in which the label was affixed on the storage container in an Example is shown, (a) is a microtube, (b) is a perspective view which shows the state in which the label was affixed on the screw cap tube. It is a cross-sectional schematic diagram which shows the structure of the label in an Example. It is a table | surface which shows the composition and component of the adhesive in an Example. It is a table | surface which shows the detail of 11 types of storage containers used for the peeling tolerance evaluation test in an Example. It is a table | surface which shows the result of the peeling tolerance evaluation test in an Example. It is a graph which shows the result of the peeling tolerance evaluation test in an Example. It is a table | surface which shows the result of the film | membrane intensity | strength measurement in the natural rubber from which sulfur content differs.

  EMBODIMENT OF THE INVENTION The form for implementing the label based on this invention is demonstrated below based on an Example.

  The label according to the embodiment will be described with reference to FIGS.

  In medical facilities such as hospitals and research facilities such as natural sciences, in order to preserve specimens such as biological tissues and cells for a long period of time, the specimens are stored in storage container 2 (container) and stored in liquid nitrogen (−196 ° C.). After being inactivated by dipping, a method of freezing for a long time at −80 ° C. in an ultra-low temperature freezer is used. Moreover, as the storage container 2 used for frozen storage in such a low temperature environment, a micro tube (see FIG. 1A) made of a resin material such as polypropylene (hereinafter abbreviated as PP) or a screw cap tube ( A tube-type sealed container such as that shown in FIG. 1B is used.

  As shown in FIGS. 1 (a) and 1 (b), the label 1 in the present embodiment describes sample identification information on a description surface 3b (see FIG. 2) to be described later, and the outer surface of the storage container 2 The sample stored in the storage container 2 and stored frozen in a low temperature environment can be identified and managed based on the identification information of the label 1 by being attached to the top surface 2b of the lid portion 2a.

  In the case of the conventional label, when the frozen storage is performed in the low temperature environment as described above, the storage container 2 that has been stored frozen is attached to the outer surface 2a of the storage container 2 or the top surface 2b of the lid portion. When removed from the ultra-low temperature freezer and moved from a low temperature environment to a room temperature environment (temperature environment of 20 ° C ± 15 ° C, which is normal temperature), the label peels off from the storage container 2 in the process of thawing the storage container 2 and the label Therefore, the identification management of the sample based on the label has become complicated. The cause of such peeling of the label is considered to be related to the thermal expansion / contraction of the storage container 2 and the label due to temperature change during freezing and thawing.

  In general, the label 1 attached to the cylindrical outer surface 2a of the storage container 2 is easier to peel than the label 1 attached to the flat top surface 2b. In an Example, it shall check about the peeling tolerance of the label 1 stuck on the outer surface 2a of the storage container 2 which is easy to peel.

  Next, the label 1 of this embodiment will be described. As shown in FIG. 2, the label 1 includes a sheet base material 3 (base material), an adhesive layer 4 (adhesive part) formed on the application surface 3 a that is one surface of the sheet base material 3, and The release paper 5 is attached to the adhesive surface 4 a of the adhesive layer 4. When the label 1 is used, the release paper 5 is peeled off from the adhesive surface 4a, and the sheet substrate 3 can be adhered to the surface of the adherend via the adhesive layer 4.

  The sheet substrate 3 is an application surface 3a to which the adhesive 40 constituting the adhesive layer 4 is applied, and a surface opposite to the application surface 3a, and can describe identification information of the specimen such as characters and barcodes. A description surface 3b. In this embodiment, a single layer material of polyethylene terephthalate (hereinafter abbreviated as PET) is used as the material of the sheet base material 3, and aluminum is deposited on the coating surface 3a. By performing corona treatment or plasma treatment on the coated surface 3a on which the aluminum is deposited, the wettability of the coated surface 3a is improved, and the adhesive 40 can be easily applied to the coated surface 3a. The adhesive strength of the adhesive layer 4 to 3a is enhanced. In addition, the single layer raw material in a present Example has shown that the film base material (PET) before processing, such as vapor deposition of aluminum, is a raw material of a single layer structure.

  The pressure-sensitive adhesive layer 4 is formed by uniformly applying a pressure-sensitive adhesive 40 with a thickness of 28 μm to the application surface 3 a of the sheet base material 3, and the pressure-sensitive adhesive surface 4 a is pressed from the outside via the sheet base material 3. As a result, it is attached to the storage container 2. Moreover, since the wettability of the application surface 3a of the sheet base material 3 is improved as described above, the adhesive layer 4 has an application surface of the sheet base material 3 compared to the adhesive force of the adhesive surface 4a to the storage container 2. When the label 1 attached to the storage container 2 is peeled off, the adhesive layer 4 is held on the application surface 3a of the sheet base 3. . The pressure-sensitive adhesive layer 4 is obtained by heat-drying the pressure-sensitive adhesive 40 applied to the application surface 3a of the sheet base material 3 to evaporate moisture and fixing the pressure-sensitive adhesive 40 in a gel form. .

  The release paper 5 has a release substrate 5 a made of paper or the like, and a release surface 5 b that is subjected to a release process on the surface with a silicone resin or the like and is in contact with the adhesive surface 4 a of the adhesive layer 4. When the label 1 is used, the release surface 5b is easy to peel off the release paper 5 from the adhesive surface 4a of the adhesive layer 4, and when the label 1 is not used, the release paper 5 is attached to the adhesive surface 4a of the adhesive layer 4. The attached state is maintained, and the deterioration of the adhesive performance due to the adhesion of dust or the like to the adhesive surface 4a is prevented. In addition, the raw material used for the peeling base material 5a and the peeling surface 5b, a processing method, etc. are not restricted to the thing of a present Example, You may be comprised freely.

  Next, the adhesive 40 that forms the adhesive layer 4 will be described. The adhesive 40 before coating is a milky white or milky white liquid at room temperature, and the composition / component ratio is about 56.0% for natural rubber and about 0.3% for ammonia as shown in FIG. Surfactant and antioxidant are about 0.5%, water is about 43.2%, and sulfur is not contained. Natural rubber refers to a mixture of natural rubber latex and a synthetic resin (rosin ester emulsion as a tackifier). Furthermore, in the manufacturing process of the label 1, the adhesive 40 applied to the application surface 3a of the sheet base material 3 is subjected to a heat drying process, and most of the water contained in the adhesive 40 is evaporated and lost. The composition / component ratio of the natural rubber and the synthetic resin in the adhesive layer 4 of the later label 1 is about 98% of the whole.

  Natural rubber, which is the main component of the pressure-sensitive adhesive 40 forming the pressure-sensitive adhesive layer 4, is mainly purified from para rubber tree sap (latex), and its chemical main component is isoprene (2-methyl-1,3-butadiene). It is. The structural formula of isoprene is shown in Chemical Formula 1 below.

  Further, in natural rubber, it exists as a string-like polyisoprene in which isoprene as a monomer is addition-polymerized. Isoprene has a plurality of addition polymerization patterns. In the case of natural rubber, cis-1,4-polyisoprene (hereinafter abbreviated as polyisoprene) in which a plurality of isoprenes are addition-polymerized by cis-1,4 bonds. )) Addition polymer structure. In the natural rubber, the number of isoprenes constituting each polyisoprene is not constant and exists in a state where the molecular weights are different from each other. The structural formula of polyisoprene is shown in the following chemical formula 2.

  Latex has been a direct expression of white milky sap collected from para rubber tree, etc., but since the development of the emulsion polymer, the polymer substance has been stably dispersed in the aqueous medium. The natural rubber latex, which is the main component of the pressure-sensitive adhesive 40 described above, is generally referred to as latex, and polyisoprene is dispersed as substantially spherical fine particles in an aqueous medium by an emulsifier or the like. It shows a heterogeneous suspension. Furthermore, the main component (50% or more) of the adhesive 40 in this embodiment may be an isoprene rubber latex using isoprene rubber synthesized using isoprene as a monomer.

  Further, in this embodiment, in order to make it easy to apply the adhesive 40 to the application surface 3a of the sheet substrate 3, a predetermined amount of polyacrylic acid ammonium salt is added as a thickener, and the adhesive 40 is adjusted to a predetermined viscosity. It is adjusted. The polyacrylic acid ammonium salt is a thickener that increases the viscosity by adsorbing water in the pressure-sensitive adhesive 40.

  The pressure-sensitive adhesive layer 4 of the label 1 in this embodiment is formed by applying a pressure-sensitive adhesive 40 having a sulfur content of 0% by mass to the coating surface 3a of the sheet base material 3 and subjecting it to heat drying treatment. Has been. As a result, the physical properties of elongation of the natural rubber or isoprene rubber made of polyisoprene are maintained, so that the adhesive layer 4 follows the thermal expansion / contraction of the storage container 2 and the sheet base material 3 during freezing and thawing. It has become easier.

  Next, the results of a peel resistance evaluation test in a low temperature environment performed on the label 1 of this example will be described. The purpose of the peel resistance evaluation test is to confirm the peel resistance of the label 1 attached to the storage container 2 under the same environment as the actual use environment.

  As an evaluation procedure in the peel resistance evaluation test, a specimen (storage container 2 with label 1 attached) was immersed in liquid nitrogen (-196 ° C.) for 1 hour, and then stored frozen in an ultra-low temperature freezer at −80 ° C. for 7 days. In the meantime, leave it in a room temperature environment (20 ° C ± 15 ° C temperature environment) until the surface of the specimen is condensed once a day every 24 hours until it is dewed. The operation of returning to the -80 ° C. ultra-low temperature freezer was performed again, and the peeled state of the label 1 was evaluated for the sample in a thawed state at room temperature. In addition, the evaluation method in the peel resistance evaluation test is a sensory evaluation, so the same person evaluates the peeling state of the label 1, and the three-stage evaluation of ○: adhesion maintenance, Δ: partial peeling, ×: peeling. The test was terminated at the time when the mark became x. In addition, as the specimens, the evaluation test was performed on a total of 33 specimens, three of each of 11 kinds of storage containers 2 (see FIG. 4) for label 1.

  Further, the label 1 attached to the storage container 2 in the peel resistance evaluation test has a dimension of 10 mm × 25 mm and the thickness of the adhesive layer 4 is 28 μm. Using an aluminum-based aluminum vapor-deposited sheet, the outer surface 2a of the sample storage container 2 whose outer periphery is shorter than the label 1 (with an outer periphery of 25 mm or less) is cut so that the end of the label 1 does not overlap. 4a was stuck to the outer surface 2a of the storage container 2.

  As shown in FIG. 5, as a result of the peel resistance evaluation test, the label 1 having a sulfur content of 0% by mass of the adhesive layer 4 has 30 ◯ and 2 △ after 7 days of freezing at −80 ° C. X became one, and about 90% of specimens were able to maintain adhesion.

  From this result, since the label 1 having a sulfur content of 0% by mass in the adhesive layer 4 has no intermolecular bonding via sulfur between the polyisoprene molecules, the elasticity of the adhesive layer 4 is not increased, and natural rubber Alternatively, the physical properties of elongation of isoprene rubber are maintained, and the adhesive layer 4 can easily follow the thermal expansion / contraction of the storage container 2 and the sheet base material 3 at the time of freezing / thawing, thereby providing high peeling resistance in a low temperature environment. It turns out that it is a label which has.

  Here, since the adhesive mainly composed of natural rubber or isoprene rubber that is generally distributed, there are some that contain sulfur by adding various additives in the manufacturing process, In order to investigate the influence of the sulfur content of the adhesive layer 4 on the peel resistance of the label, for each label having a plurality of types of adhesive layers in which the sulfur content of the adhesive layer 4 is adjusted stepwise, An evaluation test was performed by the same evaluation procedure and evaluation method.

  As shown in FIG. 6, the proportion of the specimen that could maintain adhesion as the sulfur content increased increased gradually and maintained adhesion on the label having a sulfur content of about 0.1% by mass. About 75% of specimens were completed. Further, in the label having a sulfur content of about 0.12% by mass, the ratio of the specimen that was able to maintain adhesion was about 60%, and the adhesion was maintained compared to the label having about 0.1% by mass. Since the ratio of the specimens that can be obtained is greatly reduced, it is possible to confirm a decrease in peeling resistance in each label having a sulfur content higher than about 0.1% by mass. Further, in each label having a sulfur content of about 0.1% by mass or less, the ratio of the specimen that could maintain adhesion exceeded 75%, and the peel resistance could be confirmed.

  From this result, the pressure-sensitive adhesive layer 4 of the label 1 increases the number of bonds using sulfur atoms as a medium between the polyisoprene molecules as the sulfur content increases, and the peel resistance gradually decreases. In the label 1 having the pressure-sensitive adhesive layer 4 of 0.1% by mass or less, even if the elasticity of the pressure-sensitive adhesive layer 4 is increased due to the bond using sulfur atoms as a medium between the polyisoprene molecules, natural rubber or isoprene It can be seen that the physical properties of the elongation of the rubber are maintained, and the label has a peel resistance in a low temperature environment. Accordingly, the sulfur content in the adhesive layer 4 of the label 1 is preferably 0 to 0.1% by mass.

  Moreover, as shown in FIG. 7, when film strength measurement is performed on natural rubber having a sulfur content of 0% by mass and natural rubber having a sulfur content of 0.45% by mass, the elongation is 100 to 700%. As for each stress in the state, the natural rubber having a sulfur content of about 0.45% by mass shows a larger value than the natural rubber having a sulfur content of 0% by mass, and the maximum value of the elongation is the sulfur content Is 1100% of natural rubber with 0% by mass, and 960% of natural rubber with a sulfur content of about 0.45% by mass. Furthermore, the maximum point stress when the natural rubber is extended to the limit is 7.43 MPa for natural rubber having a sulfur content of 0% by mass and 33.20 MPa for natural rubber having a sulfur content of about 0.45% by mass. It can be seen that the elasticity of the pressure-sensitive adhesive layer 4 is increased by the bond between the polyisoprene molecules using sulfur atoms as a medium, and the physical properties of the natural rubber are impaired. The physical properties of elongation of natural rubber or isoprene rubber are substantially the same, and have excellent elongation properties compared to other rubbers (for example, the maximum elongation of acrylic rubber is about 600%). ), Suitable as a main component of the adhesive layer 4 of the label 1 used in a low temperature environment.

  Moreover, about each label (The sulfur content rate of the adhesion layer 4 is 0-0.1 mass%) using the polyvinyl chloride-type sheet | seat of a single layer material, or the PP-type synthetic sheet of a multilayer structure as the sheet | seat base material 3 is mentioned above. As a result of performing the evaluation test with the same evaluation procedure and evaluation method as the peel resistance evaluation test performed, the specimen that was able to maintain adhesion was a ratio of around 10%, and therefore the single layer material PET in this example The peeling resistance excellent in the label 1 using a system aluminum vapor deposition sheet was confirmed.

The thermal expansion coefficients of PET, which is a material of a PET-based aluminum vapor deposition sheet used for the sheet base material 3 of the label 1 of this example, and PP, which is a material of 11 types of storage containers 2, are 6 to 8.5, respectively. The value is in the range of × 10 ⁻⁵ / ° C., and the thermal expansion / contraction of the storage container 2 and the sheet base material 3 by freezing and thawing can be made substantially uniform, so that it works on the adhesive layer 4. It is possible to prevent the external force from concentrating on a specific location and peeling from the concentration point of the external force. In addition, since the PET-based aluminum vapor-deposited sheet used for the sheet base material 3 of the label 1 of this embodiment is composed of a single layer material of PET, the entire sheet base material 3 is substantially uniform during freezing and thawing. Since thermal expansion / contraction can follow the pressure-sensitive adhesive layer 4, distortion of the sheet base material 3 and the pressure-sensitive adhesive layer 4 can be suppressed.

  As described above, the label 1 in this embodiment includes the sheet base material 3 and the adhesive layer 4 applied to at least one surface of the sheet base material 3, and the adhesive layer 4 is inexpensive. In addition, since the main component is natural rubber or isoprene rubber having excellent physical properties of elongation and the sulfur content is 0 to 0.1% by mass, the adhesive layer 4 is composed of polyisoprene molecules of natural rubber or isoprene rubber. Even if they are bonded between molecules via sulfur, the physical properties of the elongation of natural rubber or isoprene rubber are maintained, and the adhesive layer resists thermal expansion / contraction of the storage container 2 and the sheet base material 3 during freezing and thawing. 4 becomes easy to follow, the adhesive layer 4 can be made difficult to peel from the storage container 2, and a label suitable for use in a low temperature environment can be obtained.

  Furthermore, generally crosslinked rubber has increased structural entanglement in the molecule, so that it cannot maintain the property of elongation as a rubber in a low temperature environment, and the temperature of the glass transition temperature at which it cures. Is higher than uncrosslinked rubber. On the other hand, the pressure-sensitive adhesive layer 4 of this example has a sulfur content of 0 to 0.1% by mass, so that the elongation property is not impaired, and the glass transition temperature is lower than that of the crosslinked rubber. Become. In other words, the label 1 in this embodiment has an earlier timing at which the adhesive layer 4 starts to be deformed especially at the time of thawing, and reliably follows the adhesive layer 4 in accordance with the thermal expansion of the storage container 2 and the sheet base material 3. Can be made.

  Further, the sheet base material 3 of the label 1 is made of PET having substantially the same coefficient of thermal expansion as PP that is the material of the storage container 2, and the heat of the storage container 2 and the sheet base material 3 during freezing and thawing. Since the expansion / contraction can be made substantially uniform, the external force acting on the adhesive layer 4 is not concentrated at a specific location, and the possibility that the adhesive layer 4 is peeled from the storage container 2 can be further reduced.

  Further, the sheet base material 3 of the label 1 is composed of a single layer material of PET, and the entire sheet base material 3 is thermally expanded / contracted substantially uniformly during freezing and thawing so that the adhesive layer 4 can follow. Therefore, the distortion of the sheet base material 3 and the adhesive layer 4 is suppressed, and the stress acting on the adhesive layer 4 due to the thermal expansion / contraction of the sheet base material 3 is not concentrated on a specific location, and the adhesive surface 4a is stored in the storage container. 2 can be made difficult to peel off, and can be an optimum label for use in a low temperature environment.

  In addition, although the present Example demonstrated as an aspect by which polyacrylic-acid ammonium salt was added by the predetermined amount as a thickener with respect to the adhesive 40, it is not restricted to this but the coupling | bonding between polyisoprene molecules is influenced. If there is no or very little influence, a thickener other than ammonium polyacrylate may be added. Furthermore, the additives such as the synthetic resin (tackifier), surfactant, antioxidant, etc. that make up the adhesive 40 have no or very little effect on the bond between the polyisoprene molecules. Small ones shall be used, and crosslinking agents, crosslinking accelerators and the like that promote bonding between the polyisoprene molecules shall not be added as much as possible.

  In this embodiment, the adhesive layer 4 has been described as an embodiment formed by uniformly applying the adhesive 40 with a thickness of 28 μm to the application surface 3 a of the sheet base material 3. However, the embodiment is not limited to this, and may be freely configured such as changing the thickness and shape according to the size and use conditions of the label 1.

  In this embodiment, PET is used as the material for the sheet base material 3 and the corona treatment or the plasma treatment is performed on the aluminum vapor deposition layer formed on the coating surface 3a. The aspect of the sheet base material 3 is not limited to this, and the processing method (for example, silica vapor deposition) for the material of the sheet base material 3 and the coating surface 3a may be freely configured.

  Further, in this embodiment, a tube-type sealed container made of a synthetic resin material such as polypropylene is used as the storage container 2 to which the label 1 is adhered, but the storage container 2 to which the label 1 is adhered is used. However, the present invention is not limited thereto, and may be freely configured, such as a bag-type or box-type airtight container made of a material such as metal.

  Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments, and modifications and additions within the scope of the present invention are included in the present invention. It is.

1 Label 2 Storage container (container)
3 Sheet base material (base material)
3a Coating surface 3b Writing surface 4 Adhesive layer (adhesive part)
4a Adhesive surface 5 Release paper 5a Release substrate 5b Release surface 40 Adhesive

Claims (3)

A label having a sheet-like base material and an adhesive part formed on at least one surface of the base material, and used by being attached to a container in a low-temperature environment,
The adhesive part has a natural rubber or isoprene rubber as a main component, and a sulfur content is 0 to 0.1% by mass.   The label according to claim 1, wherein a thermal expansion coefficient of the base material is substantially the same as a thermal expansion coefficient of the container.   The label according to claim 1, wherein the substrate is made of a single layer material.

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