JP-2023183573-A - ADHESIVE LABEL

Abstract

To provide an adhesive label with excellent punching processability in a low-temperature environment, and in a high-temperature, high-humidity environment even when an adhesive label with a polyester resin base material and a polyester adhesive placed on one side of the polyester resin base material is used for a material-recycling purpose.SOLUTION: An adhesive label has a polyester resin base material and a polyester adhesive layer formed of an adhesive composition. The adhesive composition includes a polyester adhesive, a xylylene diisocyanate compound, and a tolylene diisocyanate compound.SELECTED DRAWING: None

Inventors

• SETO AYAKA
• KAWAMURA AKIRA

Assignees

• LINTEC CORP

Dates

Publication Date

20231228

Application Date

20220616

Priority Date

20220616

Claims (5)

1. It has a polyester resin base material and a polyester adhesive layer formed from an adhesive composition, The pressure-sensitive adhesive composition is a pressure-sensitive adhesive label containing a polyester pressure-sensitive adhesive, a xylylene diisocyanate-based compound, and a tolylene diisocyanate-based compound.
2. The adhesive label according to claim 1, wherein the blending mass ratio of the xylylene diisocyanate compound and the tolylene diisocyanate compound is xylylene diisocyanate compound:tolylene diisocyanate compound = 1:0.1 to 2.
3. The adhesive label according to claim 1 or 2, which is an adhesive label affixed to a polyester container.
4. A polyester container to which the adhesive label according to claim 1 or 2 is attached.
5. According to claim 1 or 2, the method comprises punching a roll-shaped adhesive sheet having a polyester resin base material, a polyester adhesive layer formed from an adhesive composition, and a release liner. A method of manufacturing adhesive labels.

Description

The present invention relates to adhesive labels. In recent years, there has been a strong desire to recycle polyester containers due to problems such as environmental pollution and depletion of petroleum resources. Among polyester containers, recycling of polyethylene terephthalate (PET) bottles is particularly desired. In material recycling of polyester containers, the container is usually crushed into flakes, then heated and melted to homogenize the whole, and the resulting recycled resin is used as the material for the polyester container. Usually, a polyester container such as a PET bottle has an adhesive label (also referred to as a label) affixed to the surface thereof on which various information is recorded. When recycling polyester containers such as labeled PET bottles, if the resin base material of the label and the resin constituting the polyester container are not compatible, the resin base material constituting the label may be A problem arises in that the material and the adhesive act as foreign substances, degrading the mechanical properties of the recycled resin. Therefore, in such a case, it is necessary to peel off the label affixed to the polyester container, then crush it into flakes, and heat and melt the container. However, the operation of peeling off a label from a polyester container is extremely complicated and time-consuming, and increases recycling processing costs, resulting in problems in terms of both operational and economical aspects. In this regard, for example, Patent Document 1 below describes a polyester resin base material that is compatible with a polyester container as an adherend, and a polyester resin base material disposed on one side of the polyester resin base material. An adhesive label having an adhesive is disclosed. According to the label configured in this way, by using the resin base material and adhesive made of the same material as the polyester container, recycling becomes possible without peeling off the label from the polyester container. Japanese Patent Application Publication No. 2000-10489 FIG. 1 is a schematic cross-sectional view showing an adhesive label according to an embodiment of the present invention.FIG. 2(A) is a schematic diagram of an embodiment of a roll-shaped adhesive sheet viewed diagonally from above. FIG. 2(B) is a schematic cross-sectional view of the adhesive sheet taken along line BB in FIG. 2(A). FIG. 2(C) is a schematic cross-sectional view of the pressure-sensitive adhesive sheet shown in FIG. 2(A) taken along the line CC. FIG. 2(D) is a schematic DD cross-sectional view of the adhesive sheet of FIG. 2(A). The present invention has a polyester-based resin base material (hereinafter also simply referred to as a resin base material) and a polyester-based adhesive layer formed from an adhesive composition, and the adhesive composition is a polyester-based resin base material. This is an adhesive label containing an adhesive, a xylylene diisocyanate compound, and a tolylene diisocyanate compound. While considering the use of a polyester resin base material and a polyester adhesive placed on one side of the polyester resin base material for the purpose of material recycling, we are considering manufacturing adhesive labels using polyester adhesives. It was discovered that if punching is performed after aging at low temperatures or in high temperature and high humidity environments, problems such as co-rolling and contamination of the punching blades will occur. Such punching workability is often improved by crosslinking the adhesive to increase its hardness. However, since polyester pressure-sensitive adhesives can basically contain functional groups (hydroxyl groups) only at the ends of the polymer main chain, it is difficult to proceed with crosslinking using a crosslinking agent. Furthermore, polyester adhesives have a lower molecular weight than general-purpose adhesives such as acrylic adhesives, and therefore it is difficult to increase the cohesive force of the adhesive. Under these circumstances, the present inventors have discovered that by using a combination of two specific isocyanate-based crosslinking agents, the subsequent punching processability is high even when aging is performed at low temperatures and in high temperature and high humidity environments. I discovered that. By combining two types of specific isocyanate-based crosslinking agents, crosslinking by the crosslinking agents proceeds appropriately even in low-temperature or high-temperature, high-humidity aging environments, and the punching properties are significantly improved. This is thought to be due to the The shape of the adhesive label is not particularly limited, but it is generally rectangular when viewed from the stacking direction. Note that the shape of the adhesive label may be triangular or circular. Further, the polyester adhesive layer is arranged, for example, on the entire surface of the resin base material. The adhesive force of the