JP3018868B2 - Heat-sensitive adhesive sheet for high-speed labelers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a non-adhesive film at normal temperature, but it exhibits adhesiveness when heated, and after the adhesiveness,
The present invention relates to a heat-sensitive pressure-sensitive adhesive sheet obtained by applying a heat-sensitive pressure-sensitive adhesive that maintains its tackiness for a while even after removing a heating source to at least one surface of a base sheet and drying.

[0002]

2. Description of the Related Art Conventionally, a heat-sensitive adhesive for a heat-sensitive adhesive sheet is used as a water-dispersed pressure-sensitive adhesive as represented by a known delayed tack-type pressure-sensitive adhesive in order to maintain the pressure-sensitive adhesive strength. Often used. For example, as described in "Adhesion Handbook" (Twelfth Edition, issued in 1955, issued by The High Polymer Publishing Association), a thermoplastic resin, a tackifier and a solid plasticizer have a basic skeleton as a composition. Thermoplastic resin is a source of adhesive strength and adhesive strength. Solid plasticizers do not impart plasticity to the resin because they are solid at room temperature, so they melt when heated to swell or soften the resin,
At normal temperature, the non-adhesive pressure-sensitive adhesive acts to develop tackiness by heating. At this time, when the tackifier is present, the tackiness is more remarkably exhibited, and the practical characteristics are improved.

However, a high-speed labeler (a heat-sensitive adhesive layer of a heat-sensitive adhesive sheet is heated to exhibit adhesiveness,
When the heat-sensitive adhesive sheet is conveyed at high speed using a machine that attaches to various objects, the heat-sensitive adhesive layer comes into contact with the conveying roller surface, etc., which is the label sending part,
Generates frictional heat. As a result, the heat-sensitive adhesive layer that is non-adhesive at room temperature is activated to some extent, becomes somewhat sticky, causes jamming or cutting in the middle of transport, and causes an accident that the sticking becomes impossible. . In such a case, it is necessary to remove the jammed portion or attach a label when the jammed portion is cut, and there is a problem that the efficiency of the attaching operation is reduced.

In order to make it difficult to generate frictional heat, it is necessary to improve the smoothness of the coated surface. A method for evaluating the smoothness of the coated surface includes Beck smoothness (JIS P8119). Japanese Patent Application Laid-Open No. 63-172784 discloses a method for applying a heat-sensitive adhesive to a sheet, which has a different purpose, and which sets the Bekk smoothness of the coated surface within a certain numerical range when the heat-sensitive adhesive is coated on the sheet. However, with a static measurement method such as Beck smoothness,
Even if the smoothness of the coated surface is as described above, a label suitable for a high-speed labeler cannot be manufactured.

[0005]

The present inventors have conducted intensive studies to overcome the above-mentioned drawbacks. As a result, a heat-sensitive adhesive sheet obtained by applying a heat-sensitive adhesive on a substrate sheet has been developed. When the dynamic friction coefficient of the pressure-sensitive adhesive-coated surface is 0.60 or less at room temperature, it has been found that even when a high-speed labeler is used for high-speed conveyance, there is no tackiness due to frictional heat, and the present invention has been achieved.

[0006]

That is, the present invention provides a heat-sensitive adhesive sheet obtained by coating a heat-sensitive adhesive containing a thermoplastic resin, a tackifier and a solid plasticizer on a base sheet. The dynamic friction coefficient of the adhesive-coated surface is
Provided is a heat-sensitive adhesive sheet for high-speed labelers of 0.60 or less.

[0007] In order to suppress the dynamic friction coefficient of the pressure-sensitive adhesive-coated surface to 0.60 or less, more preferably 0.56 or less, not only the visual unevenness (smoothness) of the coated surface is simply suppressed but also the relationship with the composition. In such a case, it is necessary to increase unevenness (smoothness). This is because simply suppressing the smoothness does not reduce the dynamic friction coefficient to 0.60 or less, and conversely, increasing the smoothness may decrease the dynamic friction coefficient to 0.60 or less.

From the viewpoint of composition, a hard thermoplastic resin, preferably a thermoplastic resin having a glass transition temperature of -5 ° C. or higher is used. However, if the glass transition temperature is too high, the film-forming property is reduced.
Examples of thermoplastic resins include acrylates, styrene-acrylates, styrene-butadiene,
Examples include ethylene-vinyl acetate, vinyl acetate, vinyl acetate-acrylate, ethylene-vinyl chloride, ethylene-acrylate, ethylene-acrylic acid, butadiene, urethane, styrene-isoprene, and acrylonitrile-butadiene polymers.

As the tackifier for improving the adhesive performance of the adhesive, conventionally known tackifiers can be used, but those having a low softening temperature have a large kinetic coefficient of friction, so that the softening temperature is low.
Those having a temperature of 80 ° C. or higher are preferred. Examples of the tackifier include terpene resins, aliphatic petroleum resins, aromatic petroleum resins, cumarone-indene resins, styrene resins, phenolic resins, terpene-phenol resins, rosin derivatives (rosin, polymerized rosin, hydrogenated Rosin and their esters with glycerin, pentaerythritol, etc., resin acid dimers, etc.).

On the other hand, examples of the solid plasticizer include diphenyl phthalate, dihexyl phthalate, dicyclohexyl phthalate, dihydroabiethyl phthalate, dimethyl isophthalate, sucrose benzoate, ethylene glycol dibenzoate, and trimethylolethane tribenzoate. , Glyceride tribenzoate, pentaerythritol tetrabenzoate, sucrose octaacetate, tricyclohexyl citrate, N-cyclohexyl-p-toluenesulfonamide and the like,
Dicyclohexyl phthalate is preferred. The particle size of the solid plasticizer has a considerable effect on the friction coefficient of the coated surface. If the particle size is too large, the dynamic friction coefficient increases, and the thermal activation time becomes longer, so that the particle size is adjusted to 10 μm or less. Is preferred.

The above-mentioned thermoplastic resin, tackifier and solid plasticizer can be used alone or as a mixture of two or more. In addition to the heat-sensitive adhesive of the present invention, a solvent, a liquid plasticizer and the like can be added for the purpose of improving the surface shape of the coated surface. In addition, fillers and the like can be added as long as the object of the present invention is not hindered. For example, titanium oxide, alumina, kaolin, talc, colloidal silica and other inorganic substances, paraffin, natural wax,
Organic substances such as synthetic waxes and natural fats and oils, and resin powders can be used. Further, if necessary, a dispersant, an antifoaming agent, a thickener and the like can be used.

[0012]

The present invention will be specifically described below with reference to examples. However, the scope of the present invention is not limited at all by the following examples. In the examples, parts are parts by weight,
% Means% by weight, respectively. [Examples 1 to 10 and Comparative Examples 1 to 10] First, a solid plasticizer, a maleic acid-based resin solution and water were placed in a ball mill according to the formulation shown in Table 1, and the mixture was ground for the time shown in Table 1 and then adhered. A tackifier, a resin emulsion and an additive were added, and mixed and stirred for 5 minutes to prepare an adhesive. The obtained pressure-sensitive adhesive was directly applied onto one-sided art paper so that the coating amount was 20 g / m ^2, and dried at 45 ° C. for 30 seconds. No tackiness could be confirmed in the state after drying. About the coating,
Table 1 shows the results of evaluation of the adhesive force, the coefficient of dynamic friction, and the high-speed labeling property.

[0013]

[Table 1] * 1 Styrene-butadiene copolymer * 2 Ethylene-vinyl acetate copolymer

The method of evaluating the coated product is described below. Adhesive force: The coated product was heated at 120 ° C for 25 seconds to develop adhesiveness, then immediately adhered to a stainless steel plate, and the adhesive strength was measured by peeling it 180 degrees according to JIS K-6848. Judgment was made based on the following criteria. However, the glued part is 100mm
And ◎ ・ ・ ・ 800g / 25mm or more. ○ ・ ・ ・ ・ ・ ・ 600g / 25mm or more and less than 800g / 25mm. ×: Less than 600g / 25mm.

Dynamic friction coefficient: The dynamic friction coefficients of the coated articles were measured in accordance with JIS P-8147.

High-speed labeling property: The coated product is formed into a roll, and is applied to a high-speed roll labeler manufactured by Koyo Automatic Machinery Co., Ltd., and a labeling test (800 sheets or more per minute) is actually performed. The time at which the presence or absence occurred was measured, and judged based on the following criteria. ◎ ・ ・ ・ ・ ・ ・ No trouble for 1 hour or more. ○ ・ ・ ・ ・ ・ ・ No trouble within 10 minutes. ×: Trouble occurred within 10 minutes.

[0017]

According to the present invention, a heat-sensitive adhesive sheet having excellent suitability for high-speed labeling can be obtained.
The present invention contributes to increasing the industrial significance of heat-sensitive adhesive sheets that can pursue economic benefits in resource savings, such as labels, tapes and seals of packages that do not require release paper, Its significance is enormous.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akira Kikuchi Examiner Osamu Sato of Toyo Ink Manufacturing Co., Ltd. 2-3-13 Kyobashi, Chuo-ku, Tokyo (56) References JP-A-63-172784 (JP, A) JP-A-52-27479 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09J 7/02 G09F 3/10

Claims (4)

(57) [Claims] 1. A heat-sensitive adhesive sheet obtained by applying a heat-sensitive adhesive containing a thermoplastic resin, a tackifier and a solid plasticizer onto a substrate sheet, wherein the dynamic friction coefficient of the pressure-sensitive adhesive-coated surface is A heat-sensitive adhesive sheet for high-speed labelers, which is 0.60 or less at room temperature. 2. The heat-sensitive adhesive sheet according to claim 1, wherein the glass transition temperature of the thermoplastic resin is from -5 ° C. to 50 ° C. 3. The heat-sensitive adhesive sheet according to claim 1, wherein the thermoplastic resin is a styrene-butadiene copolymer. 4. The heat-sensitive adhesive sheet according to claim 1, wherein the thermoplastic resin is an acrylic polymer.