JP2000212525A - Tacky tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively and easily obtain a tacky tape having exceedingly improved adhesiveness to an ink by subjecting a face, etc., of a polystyrene- based film brought into contact with a silicone layer to a corona discharge treatment. SOLUTION: This tacky tape is composed of a polystyrene-based film such as a butadiene-styrene copolymer and having a silicone layer on one face and an ultraviolet ray-hardening printing ink layer and a tacky agent layer on the reverse face and all of the face attaching to the silicone layer and the face attaching to the ultraviolet ray-hardening printing ink layer of the polystyrene-based film are treated with a corona discharge treatment. The ink used for the UV-hardening printing can be used as a known ink and a vinyl monomer having miscibility with a prepolymer having an addition polymerization property and having copolymerizability and a copolymerization initiator are used as main agents to form a stabilizer or various pigments as a coloring agent.

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 tape, and more particularly to a polystyrene-based pressure-sensitive adhesive tape on which ultraviolet curing printing (hereinafter referred to as UV curing printing) has been performed.

[0002]

2. Description of the Related Art In recent years, the amount of polystyrene-based pressure-sensitive adhesive tapes used has been increasing as a pressure-sensitive adhesive tape which is attached to a foamed polystyrene box to indicate contents, standards, manufacturers, and the like. This is because when the foamed polystyrene box is collected and recycled, the tape attached to the box is preferably made of the same material as the box.

By the way, as a printing method on a tape, a label or the like, a UV curing printing method can cure and dry an ink by cold energy of ultraviolet irradiation, so that various kinds of plastics, laminates, etc. including papers can be dimensionally stabilized or made of a material. Since it has an extremely great advantage that high-speed printing can be performed without deteriorating the image quality, a wide range of applications are expected.

[0004] However, UV-curable printing inks have poor adhesion and adhesion to polystyrene-based films, making UV-curable printing virtually impossible. For this reason,
For example, gravure printing on polystyrene labels,
Acrylic oligomer is applied to the surface of a polystyrene film to perform UV curing printing (JP-A-6-13511).
No. 9).

[0005]

However, gravure printing is not suitable for the production of an adhesive tape from the viewpoint of cost in the case of small-scale production, and an acrylic oligomer is applied to the surface of the polystyrene film to form a UV. Curing printing also increases the cost. In addition, in the case of the pressure-sensitive adhesive label using release paper, the UV-cured printed surface did not directly contact the pressure-sensitive adhesive layer, so that the ink adhesion could be used even if it was not necessarily good. However, usually, a pressure-sensitive adhesive layer is provided on UV-cured printing, and in the case of a pressure-sensitive adhesive tape wound without release paper, a release agent layer is provided on the film to prevent adhesion between adjacent films. However, depending on the degree of adhesion between the release agent layer and the pressure-sensitive adhesive layer, the ink may peel off from the substrate film and adhere to the next film together with the pressure-sensitive adhesive layer. Need to be at a higher level. In addition, when the adhesive tape is applied to the box by mistake and the tape once applied is peeled off, if the adhesive between the box and the tape is strong and the adhesion of the ink is insufficient, the ink will be transferred to the box. Therefore, the adhesion of the ink to the base film needs to be at a higher level.

The present invention overcomes the above disadvantages of the prior art,
An object of the present invention is to provide a pressure-sensitive adhesive tape having improved adhesion between a UV-curable printing ink and a polystyrene-based film as a base film.

[0007]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have accomplished the present invention. That is, the present invention is a pressure-sensitive adhesive tape formed by forming a silicone layer on one side of a polystyrene-based film and an ultraviolet-curable printing ink layer and a pressure-sensitive adhesive layer on the other side,
A pressure-sensitive adhesive tape, wherein both the surface of the polystyrene film that contacts the silicone layer and the surface that contacts the ultraviolet-curable printing ink layer are subjected to corona discharge treatment. Hereinafter, the present invention will be described in detail.

The polystyrene constituting the base film used in the present invention is, for example, a polystyrene, a polystyrene copolymer such as a butadiene-styrene copolymer or a styrene-acrylonitrile copolymer, or polystyrene and polybutadiene or a copolymer thereof. Selected from a mixture of This base film is preferably a stretched film. Further, from the viewpoint of the cuttability of the adhesive tape, when the transverse stretching ratio is λTD and the longitudinal direction is λMD, 2 ≦ λ
It is preferable that TD <λMD.

Since the substrate film used in the present invention is subjected to a printing process or the like, it is preferable that the substrate film has a strong stiffness. For example, a tensile modulus (2% elongation: in accordance with ASTM-D-882, a tensile speed of 10% / (measured in minutes) is preferably 2 to 6 GPa. In addition, from the viewpoint of cutability, tensile elongation (AS
(Measured at a tensile speed of 10% / min in accordance with TM-D-882) is preferably 70% or less. In addition, gloss (ASTM-D-24)
(Measured in accordance with No. 57) is preferably 160% or more.

The pressure-sensitive adhesive tape of the present invention needs to be subjected to corona discharge treatment on one side of a polystyrene film and then to UV-cured printing. By performing the corona discharge treatment prior to the UV printing, the adhesiveness between the UV-curable printing ink layer and the polystyrene-based film as the substrate is significantly improved. As for the degree of the corona discharge treatment, the surface tension measured by a wetting test method is preferably 39 dyn / cm or more, and more preferably 42 dyn / cm or more. Here, the wetting test method is JIS
-K-6768 refers to a wetting test method applied to a polystyrene-based film using "Method for testing wetness of polyethylene and polypropylene films". The surface tension of the polystyrene film can be adjusted by corona discharge treatment. Corona discharge treatment is performed with electrodes connected to a high-voltage generator, for example, polyester, Hypalon, EP
0.5 ~ between metal roll covered with rubber etc.
With a clearance of about 0.6 mm, a high frequency of several hundred kc / s is applied at a high voltage of several thousand to several tens of thousands volts, and the equipment can be run at a constant speed in this gap by a usual method.

[0011] Known inks can be used for the UV curing printing, and are mainly composed of a copolymerizable vinyl monomer and a copolymerization initiator which are compatible with an addition polymerizable prepolymer (eg, acrylic resin). Stabilizers and various pigments are used as colorants. In addition, a known ultraviolet irradiation device or the like can be used as it is. The pressure-sensitive adhesive tape of the present invention further comprises a pressure-sensitive adhesive layer on the UV-curable printing ink layer. Acrylic is used as the adhesive constituting the adhesive layer,
There are natural rubber-based, urethane-based, synthetic rubber-based, vinyl-based homopolymers and copolymers containing 50% by weight or more of any of them, and the form is 40-60% by weight of emulsion type, hot melt type, 20-45% by weight. % Of the solvent type, and more specifically, "CT116" of Cemedine Co., Ltd. for emulsion type of natural rubber, "HM655" of Cemedine Co., Ltd. for hot melt type of synthetic rubber, and vinyl copolymer type emulsion. Examples of the mold include "Life Bond AV-650 Series" manufactured by Niei Kakosha. From the viewpoint of ease of handling, a hot-melt pressure-sensitive adhesive is preferred.

The amount of the adhesive applied is preferably 5 g / m ² or more. If it is less than 5 g / m ² , the adhesive strength tends to be insufficient. In the pressure-sensitive adhesive tape of the present invention, it is necessary that the surface opposite to the UV-curable printing ink layer is subjected to a corona discharge treatment and then cured silicone is applied. Here, the degree of the corona discharge treatment is as follows: the surface tension by the wetting test method is 39 dyn / cm or more,
It is preferably at least n / cm.

The silicone used in the present invention is preferably of a curable type, and may be appropriately selected and used such as heat curing and UV curing. As the curable silicone release agent, those obtained by mixing and dispersing an addition silicone, a platinum-based catalyst and an acetylene-based curable retarder in a solvent are preferable.As the solvent, hexane, heptane or these having little influence on the polystyrene film are used. Are preferred.
The amount of each component of the preferred silicone release agent is 3 to 7 platinum-based catalysts per 100 parts by weight of the additional silicone.
Parts by weight, 6 to 14 parts by weight of an acetylene-based curing retarder, and 500 to 1500 parts by weight of a solvent. The amount of the curable silicone to be applied is 500 mg / m ^2-
It is preferably 20 g / m ² .

When producing the pressure-sensitive adhesive tape of the present invention, any of silicone coating and UV curing printing may be performed first. However, if both sides of the polystyrene film are corona-discharged and wound, blocking will occur. If it has a winding step in the middle, it is necessary to avoid exposing the corona discharge-treated surface on both sides of the polystyrene film during winding, and it is difficult to apply silicone coating. It is necessary to wind it up by processing. In addition, when there are various patterns for printing, and when the number of lots of each printing is small, it is preferable in terms of manufacturing efficiency to perform the steps up to UV curing printing collectively. For example, after applying the silicone after corona discharge treatment and winding once, applying the UV curable printing by corona discharge treatment on the other surface, providing a pressure-sensitive adhesive layer and winding and applying corona discharge treatment to both surfaces A method in which a silicone layer is formed on one side and once wound up, followed by UV curing printing to form an adhesive layer is preferred.

In the present invention, a polystyrene film is used as a base material for the purpose of obtaining an adhesive tape. However, the technology of the present invention can be applied to other forms such as an adhesive label. The form of the material may be a sheet, a plate, or the like according to the application.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited thereto.

[0017]

Example 1 Thickness 50 μm, tensile modulus (vertical / horizontal)
2.8 GPa / 3.5 GPa, tensile elongation (vertical / horizontal)
One side of a 40% / 45%, 170% gloss biaxially stretched polystyrene film was subjected to corona discharge treatment using a “HF403” type corona discharge treatment device manufactured by Kasuga Electric Co. (substrate having a surface tension of 45 dyn / cm). 6 g / m ² (by wet) of a curable silicone release agent obtained by adding a catalyst and a retarder to a 7% by weight solution of silicone in heptane was applied on a gravure type printer, dried and wound up. Further, the opposite surface was subjected to a corona discharge treatment using a “HF403” type corona discharge treatment device manufactured by Kasuga Denki Co., Ltd. (the surface tension of the substrate was 40 dyn / cm). After UV curing printing under the following conditions using a light set LS SAP manufactured by
g / m ² ) and wound up.

(Printing conditions) UV lamp output: 120 w / cm, 3-pass line speed: 20 m / min A cellophane tape peeling test of a printed product of this tape showed no peeling of the ink and no problem in ink adhesion.

[0019]

Comparative Example 1 The same surface as in Example 1 was prepared except that the treated surface of the UV-curable printing ink was not subjected to corona discharge treatment. A cellophane tape peeling test showed that the ink was easily peeled off and the adhesion was poor.

[0020]

According to the present invention, a polystyrene-based pressure-sensitive adhesive tape having significantly improved ink adhesion can be easily provided at low cost.

Claims (1)

[Claims] 1. A pressure-sensitive adhesive tape comprising a polystyrene-based film having a silicone layer on one surface and an ultraviolet-curable printing ink layer and a pressure-sensitive adhesive layer formed on the other surface, wherein the polystyrene-based film is in contact with the silicone layer. And a surface in contact with the ultraviolet-curable printing ink layer, all of which have been subjected to corona discharge treatment.