JPH0683267A - Antistatic adhesive label - Google Patents

Abstract

PURPOSE:To prevent the trouble by the electrification on the surface of the adhesive of the adhesive label constituted of a base, an adhesive layer and release sheet in this order by mixing a conducting agent with the adhesive layer. CONSTITUTION:The conducting agent to be mixed with the adhesive layer includes an electron conductive material and an ion conductive material, both of which are usable. Examples of the electron conductive material include metallic powder, metal oxide and carbon black. Conductive particulates formed by adhering the electron conductive material to the surfaces of flat shaped particulates of mica, etc., and acicular particles, such as whiskers are used as well. These electron conductive materials are added at 2 to 10wt.% of the solid content of the adhesive. Both inorg. and org. materials are usable as the ion conductive material. The representative example of the org. material is a metal salt. The org. materials include an anion system and cation system. These ion conductive materials are added at 5 to 20wt.% of the solid content of the adhesive. As a result, the peeling and electrification are prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive label that is used by being attached to a product, luggage, envelope, etc.

[0002]

2. Description of the Related Art Conventionally, an adhesive label has been used as a means of displaying a price or the like on a product sold at a store, and also attached to the surface of a container, a parcel of a courier, or an envelope. And is used for various purposes.
The pressure-sensitive adhesive label has a constitution of a support, a pressure-sensitive adhesive layer, and a release sheet, and at the time of use, the pressure-sensitive adhesive label is attached to an object by peeling off the release sheet and the pressure-sensitive adhesive layer. Usually, some characters or pictures are printed on the surface of the support before sticking and using, but it may be printed or written after sticking the label. In many cases, as an industrial step, a step of printing on an adhesive label, subsequently peeling the label from the release sheet, and then affixing it to an object is carried out. A machine that automatically performs such a process is called an automatic labeler.

[0003]

In the automatic labeler, the peeling electrification has never been a big problem in the past, and until now, the antistatic property of the adhesive layer has not been considered. The reason is that the speed of the automatic labeler has been slow in the past and was not enough to cause peeling charge. However, as the speed of the automatic labeler increased and the peeling was performed at a higher speed, the charging phenomenon was observed in the adhesive layer. Further, in recent years, a synthetic resin film is often used as a support. When a synthetic resin film is used as a support, the film itself has a higher charging property than paper, and the fact that a synthetic resin film is generally thinner than paper also has an effect. large.

On the other hand, a thermal recording method is increasingly used as a labeler printing method. In heat-sensitive recording such as a facsimile, there has been a problem that a recording surface or a back surface is rubbed against a recording head or a roll and charged. Since a heat sensitive recording uses a special chemical, it is not preferable to put a conductive agent in the heat sensitive recording layer, and a conductive agent is applied to the back surface of the support. The problem of triboelectrification also exists in the case of pressure sensitive adhesive labels using a thermal recording system. Also in this case, it is effective to apply the conductive agent to the back surface of the support. However, even if the back surface of the support has good conductivity, it has little effect on the peeling charge of the pressure-sensitive adhesive layer and the release sheet, and in addition to this, it is necessary to prevent the charge of the pressure-sensitive adhesive.

In view of the above points, it is an object of the present invention to provide a pressure-sensitive adhesive label in which troubles due to electrification of the pressure-sensitive adhesive surface are prevented.

[0006]

The present invention adopts the following configurations as means for solving the above problems. That is, the present invention is an "adhesive label comprising a support, an adhesive layer, and a release sheet in this order, in which a conductive agent is mixed in the adhesive layer".

As the material used as the support of the present invention,
Examples include paper, synthetic paper, and synthetic resin film. As the paper, high-quality paper, medium-quality paper, and coated paper are used. As the synthetic paper, paper made of synthetic pulp into paper, paper coated with a coating on the surface of a synthetic resin film, or paper in which a filler or air bubbles are incorporated in the synthetic resin film can be used. As the synthetic resin film, various general-purpose products such as polyolefin type, polyester type and polyamide type can be used. For the sake of simplicity, the term "synthetic resin film" will be used herein including synthetic paper using synthetic resin film and ordinary synthetic resin film.

As the support of the present invention, a paper or a synthetic resin film provided with a surface layer suitable for recording various information is used. As the recording layer, those provided with a thermosensitive recording layer, those provided with a recording layer for thermal transfer recording, and the like can be used.

The pressure-sensitive adhesive used in the pressure-sensitive adhesive layer of the present invention is a mixture of a natural rubber, a synthetic rubber, a synthetic resin and the like, if necessary, with a tackifier and a plasticizer. Examples of the synthetic rubber or synthetic resin include styrene / butadiene copolymer system, polyisobutylene system, chloroprene rubber system, butadiene / acrylonitrile copolymer system, polyvinyl ether copolymer system, and polyacrylic acid ester system. Examples of the tackifier include polyterpenes, gum rosins, rosins and rosin derivatives, coumarone-indene resins, petroleum hydrocarbons and the like. Examples of the plasticizer include phthalic acid ester, phosphoric acid ester, chlorinated paraffin, and the like.

As the conductive agent used in the present invention, there are an electron conductive substance and an ion conductive substance, and both can be used. Examples of electronic conductivity include metal powder, metal oxides, carbon black, and the like. Further, flat fine particles such as mica, and conductive fine particles in which an electron conductive substance is attached to the surface of needle-like fine particles such as whiskers are also used. As a substance to be attached to the surface,
Examples thereof include carbon, tin oxide, antimony oxide and the like.
These electronically conductive substances have a solid content of 2 to 2
Add 10% by weight.

As the ion conductive substance, either an inorganic type or an organic type can be used. A metal salt is a typical example of the inorganic type. As the organic type, either anionic type or cationic type can be used. Examples of the metal salt include sodium chloride and calcium chloride. Examples of the anionic conductive agent include a polymer or copolymer of an unsaturated carboxylic acid salt, a polymer or a copolymer obtained by polymerizing an unsaturated monomer having a sulfonate group or a phosphate group, and the like. Examples of cationic conductive agents include fatty acid quaternary ammonium salts. Among the ion-conductive substances, unsaturated styrene sulfonate polymer, acrylate-based polymer or copolymer are preferable. These ion conductive substances are added in an amount of 5 to 20% by weight based on the solid content of the adhesive. The amount of addition is not necessarily limited depending on the kind of the conductive agent, but in any case, if the surface resistance of the pressure-sensitive adhesive layer is less than 1 × 10 ¹¹ at 20 ° C. and 65% RH, the above object is achieved.

[0012]

According to the method of the present invention, the volumetric electric resistance of the pressure-sensitive adhesive is lowered, and peeling-off charge generated between the peeling layer and the pressure-sensitive adhesive layer can be prevented. When the conductive agent is electron conductive fine particles, the flat or needle-shaped conductive fine particles are preferable in that the adhesive effect is not impaired because the conductive effect is exhibited in a small amount because there are many opportunities for the particles to come into contact with each other. it is conceivable that. When the conductive agent is an ion conductive material, it needs to be added in a larger amount than the electron conductive material. However, if an appropriate polymer conductive agent is selected, the tackiness of the pressure-sensitive adhesive will not be impaired even if added in a large amount. For example, sodium polystyrene sulfonate can be used for styrene-butadiene based adhesives, and sodium polyacrylate can be used for acrylic based adhesives, since they will be sufficiently mixed with the adhesive. Will not hurt.

[0013]

EXAMPLES The present invention will be described below with reference to examples. (Preparation of release sheet and support) A fine paper of 80 g / m ² in weight per square meter was coated with 15 μm of polyethylene, and a silicone resin coating was applied thereon to obtain a release sheet. A 12 μm-thick biaxially stretched polyethylene terephthalate film (hereinafter abbreviated as PET film) was attached to a release sheet with an adhesive containing the following conductive agent to obtain an adhesive label.

(Adhesive containing conductive agent) Styrene 35
Parts, 45 parts of butadiene, and 20 parts of butyl acrylate, 4 parts by weight of conductive whiskers (Otsuka Chemical WK
-200; Potassium titanate whiskers whose surface was coated with tin oxide and antimony oxide) were mixed and stirred to obtain.

(Preparation of Thermal Recording Layer) A thermal recording layer was formed on the PET film by the following procedure.

Liquid A Preparation Crystal Violet Lactone 5 parts Zinc Stearate 10 parts Calcium Carbonate 27 parts Sodium Polyacrylate 10% Aqueous Solution 5 parts Polyvinyl Alcohol 12% Aqueous Solution 30 parts Water 50 parts Disperse a composition for 12 hours with a paint shaker. The solution was treated to obtain solution A. Liquid B preparation 4,4'-isopropylidenediphenol 15 parts Calcium carbonate 27 parts Sodium polyacrylate 10% aqueous solution 5 parts Polyvinyl alcohol 12% aqueous solution 30 parts Water 50 parts A composition consisting of 50 parts is dispersed for 12 hours with a paint shaker. To obtain solution B. Formation of Recording Layer Separately dispersed liquids A and B were mixed, and 65 parts of a 12% aqueous solution of polyvinyl alcohol was added to prepare a heat-sensitive paint. This heat-sensitive paint is applied to the PET film in a solid content of 7
It was applied and dried so as to be g / m ² to obtain a heat-sensitive recording type adhesive label.

(Evaluation) Thus, the heat-sensitive recording type adhesive label thus obtained was peeled from the release paper and attached to the bottle while heat-sensitive recording was carried out by a high-speed automatic labeler, but there was no problem that the label curled due to electrification. Did not occur.

[0018]

EFFECTS OF THE INVENTION According to the present invention, a pressure-sensitive adhesive label free from peeling charge even when a high-speed automatic labeler is used can be obtained. Further, in the case of heat-sensitive recording, it is preferable to apply an antistatic agent on the back surface of the support, but according to the present invention, since the adhesive in contact with the support also serves that role, the back surface of the support is charged. The application of the inhibitor can be omitted, and the process can be simplified.

Claims (1)

[Claims] 1. A pressure-sensitive adhesive label comprising a support, a pressure-sensitive adhesive layer and a release sheet in this order, wherein a conductive agent is mixed in the pressure-sensitive adhesive layer.