JPH06104390B2 - Adhesive sheet for stamps - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an adhesive paper type stamp (including stamp) paper, and particularly when sticking, it can be stuck as it is without being wet,
The present invention relates to an improvement of a pressure-sensitive adhesive sheet for stamps, which can be easily peeled off by applying water when peeling is required.

(Prior Art) Stamps, stamps, etc. that have been conventionally used (these are collectively referred to as stamps in the present invention) have a water-soluble polymer adhesive such as dextrin or polyvinyl alcohol applied and dried on the back surface of the stamp. Things are being used. Therefore, when a stamp collector removes a used stamp from a postcard, an envelope or the like, it can be easily removed by soaking it in water. However, when sticking a stamp on a postcard, envelope, or the like, a method of sticking the water-soluble adhesive layer surface by wetting it with water, for example, is adopted. However, there is a case where there is no water at hand when sticking the stamp. In such a case, it is often wet with saliva and attached. This is not very hygienic, nor is it visually pleasing.

Further, in a place where a large amount of stamps are stuck, it takes a lot of time and labor to stick the stamps to each other if they are wet with water.

Further, when the wetness is insufficient, the adhesive force is not sufficiently exerted and the attachment becomes incomplete.

As a result, it is possible to attach stamps easily and efficiently.
An adhesive paper type stamp as described in 6-108167 has been proposed. The stamps described in these documents are configured such that the stamps attached to the release paper can be peeled off at the time of use and can be stuck as they are.

Therefore, the stamp has to be able to be stuck and used always stably under any environmental condition. If the stamp is a conventional one that is simply coated with a water-soluble polymer adhesive on the back side, there is no problem in terms of function as long as it is sufficiently wet wherever it is used. However, when the stamp paper is configured as an adhesive paper type, the adhesive has a problem of weather resistance due to changes in the surrounding environment such as adhesive properties, light, humidity and heat, especially when the adhesive is attached at low temperature, and the small size of the stamp paper. A problem is caused in the punching suitability of a product.

For example, acrylic solvent-based adhesive (generally contains many polar groups such as carboxyl and hydroxyl groups)
When the humidity is high, the pigment contained in the base material of the stamp or the water-soluble polymer adhesive layer reacts with the carboxyl group or hydroxyl group in the pressure-sensitive adhesive to lower the adhesive strength. There is a problem. Further, when an acrylic solvent-based pressure-sensitive adhesive that is cross-linked by isocyanate is used, there is a problem that the pressure-sensitive adhesive turns yellow due to light and the quality of the stamp is deteriorated. Due to its original properties, rubber-based adhesives are susceptible to deterioration of the adhesive due to light.
There is a problem in weather resistance such that the adhesive component is likely to permeate and migrate to the printing paper support due to heat and long-term storage. Rubber-based adhesives are more likely to cause troubles due to defective adhesive when punching into smaller stamps.

(Problems to be Solved by the Invention) The present invention is a pressure-sensitive adhesive paper type stamp which can be easily peeled off by applying water when peeling off, and can be stably stuck and used under any environmental conditions. The purpose is to provide an adhesive sheet for stamps.

(Means for Solving the Problem) The inventors of the present invention have conducted extensive studies to develop the pressure-sensitive adhesive sheet for stamps, and as a result, completed the invention having the following configuration. That is, the present invention is a pressure-sensitive adhesive sheet for printing, comprising a paper for printing having a water-soluble adhesive layer on the back surface and a release paper bonded via an adhesive layer, wherein the glass transition temperature of the adhesive is less than -35 ° C. In the pressure-sensitive adhesive sheet for stamps, an acrylic emulsion-type pressure-sensitive adhesive containing less than 4% of an ethylenically unsaturated carboxylic acid-containing monomer is used.

(Function) In the above invention of the present application, the most distinctive feature is an acrylic emulsion type which has a glass transition temperature of less than -35 ° C as an adhesive and contains less than 4% of an ethylenically unsaturated carboxylic acid-containing monomer. Although an adhesive is used, it has been confirmed that this adhesive has excellent properties that other adhesives do not have when a stamp is made into an adhesive paper type.

That is, this adhesive has little change in adhesive physical properties even under storage at high temperature and high humidity, and exhibits sufficient adhesive force when used at low temperature, causing yellowing due to light, adhesive component to the support. There is no problem such as permeation shift. In addition, it is also good at removing glue when punching stamps. It has been confirmed that it is excellent in suitability for the production of stamps and has suitable conditions as a pressure-sensitive adhesive for stamps without any trouble in quality and use under any environmental conditions.

Acrylic emulsion type adhesive used in the present invention,
Although the glass transition temperature is specified to be less than -35 ° C,
This is to maintain a sufficient adhesive force even under low temperature conditions (for example, 0 ° C. or lower). (If the glass transition temperature is -35 ° C or higher, the adhesive strength will not be exhibited in a low temperature environment.) In order to maintain sufficient adhesive strength in an extremely cold environment such as an ambient temperature of -5 ° C or lower, glass is required. Transition temperature
It is desirable to use those below 45 ° C. Further, the acrylic emulsion-type pressure-sensitive adhesive used in the present invention is specified to have an ethylenically unsaturated carboxylic acid content of less than 4% if it contains 4% or more under high humidity. This is because the pigment contained in the base material of the stamp or the water-soluble polymer adhesive layer reacts with the carboxyl group or hydroxyl group in the pressure-sensitive adhesive to reduce the adhesive strength. However, the content of ethylenically unsaturated carboxylic acid is 4%
When the amount is less than the above, such a reaction is small, the adhesive physical properties are stable even under high humidity, and the decrease in the adhesive force is small. Regarding the content of ethylenically unsaturated carboxylic acid,
Less than 4% is desirable, but more preferably 2%
Less than one is better.

Thus, as the upper paper for stamps for forming the pressure-sensitive adhesive sheet for stamps according to the present invention, high-quality paper, medium-quality paper, art paper,
General printing paper such as coated paper and cast coated paper, metallized paper, synthetic paper, film and the like can also be used.

Specific examples of the water-soluble adhesive to be applied to the back surface of the printing paper, dextrin, starch, polyvinyl alcohol, carboxymethyl cellulose, casein, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, polyethylene oxide, carboxymethyl starch, dialdehyde starch, There are polyvinyl methyl ether, polyvinyl pyrrolidone, gum arabic, gum tragacanth, sodium polyacrylate, water-soluble acrylic resin, oxidized starch, fluid starch and the like, and these may be used alone or in combination of two or more kinds. In these water-soluble adhesive layers, for example, kaolin, clay, silica powder, colloidal silica, talc, alumina white, satin white, zinc white, lithobon, other magnesium, aluminum, calcium, barium, zinc, titanium, or silicon. Oxides, hydroxides, carbonates, sulfates or silicates of magnesium hydroxide, magnesium carbonate, magnesium sulfate, magnesium silicate, magnesium oxide, calcium hydroxide, calcium carbonate, calcium hydroxide, calcium carbonate, calcium sulfate Pigments such as calcium silicate, barium sulfate, zinc oxide, zinc carbonate, zinc sulfate, titanium oxide and silicon oxide can be used alone or in combination of two or more kinds. The amount of the pigment contained in the water-soluble adhesive layer is 3 to the solid content of the water-soluble adhesive.
Within the range of 95% by weight, preferably 5-80% by weight, more preferably 10-50% by weight. If the amount is 3% by weight or less, the adhesive strength between the water-soluble adhesive layer and the pressure-sensitive adhesive layer cannot be sufficiently exhibited. On the other hand, if it is contained in an amount of 95% by weight or more, the peelability will be poor even if it is immersed in water to peel from the adherend, and the desired product cannot be obtained.

Furthermore, in the water-soluble adhesive layer, in addition to the pigment, styrene-
For example, butadiene copolymer, methylmethacrylate-butadiene copolymer, vinyl chloride copolymer, vinylidene chloride copolymer, acrylic copolymer, vinyl acetate copolymer, ethylene-vinyl acetate copolymer latex, etc. It is also possible to add various auxiliaries and the like according to the above.

Next, as a release paper used for forming an adhesive sheet by bonding with the above-mentioned stamp paper, glassine paper, clay-coated paper, kraft paper or high-quality paper is coated with polyvinyl alcohol or polyethylene with a barrier coat or laminated. Those coated with or impregnated with a release agent such as a silicon compound or a fluorine compound are used.

Examples of the present invention will be described below, but it goes without saying that the present invention is not limited to these examples.

(Example 1) Art paper (Kanzaki Paper Co., Ltd. Super Art Kinto 80g /
m ² ) on the back side of polyvinyl alcohol (Kuraray Co., Ltd.)
An aqueous dispersion having a solid ratio of PVA-105) and kaolin of 5: 2 was applied and dried to a dry weight of 7 g / m ² to form a stamp paper. Then, on a commercially available polyethylene laminated release paper, a glass temperature of −45 ° C. or less and an acrylic emulsion type adhesive (AF94A manufactured by Saiden Chemical Co., Ltd.) having an ethylenically unsaturated carboxylic acid content and a unit amount of 2% or less were dried at 25 g / m
^It was applied and dried so as to be ² . Next, the above-mentioned stamp paper and release paper are laminated to form an adhesive sheet.

Adhesiveness of this adhesive sheet in low temperature environment, light resistance,
The heat resistance, moisture resistance, and punchability are shown in the attached table.

(Example 2) 68 parts by weight of 2-ethylhexyl acrylate, vinyl acetate 11
1 part by weight of polyoxyethylene nonylphenol and 1 part by weight of sodium dioctylsulfosuccinate as an emulsifying agent, and glass temperature of -35 ° C or less, ethylenic An acrylic emulsion-type pressure-sensitive adhesive having a saturated carboxylic acid-containing monomer of 4% or less was obtained. Using this adhesive, an adhesive sheet for stamps was prepared in the same manner as in Example 1.
The adhesiveness, light resistance, heat resistance, moisture resistance and punching suitability of this pressure-sensitive adhesive sheet for stamps in a low temperature environment are shown in the attached table.

(Comparative Example 1) 63 parts by weight of 2-ethylhexyl acrylate, 20 parts by weight of methyl methacrylate, 12 parts by weight of vinyl acetate, 5 parts by weight of acrylic acid as an emulsifier, 1 part by weight of polyoxyethylene nonylphenol ether, 1 part by weight of sodium dioctylsulfosuccinate. Emulsion copolymerized with a glass transition temperature of -35
4% or more of ethylenically unsaturated carboxylic acid-containing monomer
The above acrylic emulsion type pressure-sensitive adhesive was obtained.

Using this adhesive, an adhesive sheet for stamps was prepared in the same manner as in Example 1. This pressure-sensitive adhesive sheet for stamps has particularly poor adhesion suitability and moisture resistance in a low temperature environment, and lacks suitability as a pressure-sensitive adhesive sheet for stamps. The adhesiveness, light resistance, heat resistance, moisture resistance and punching suitability of this pressure-sensitive adhesive sheet for stamps in a low temperature environment are as shown in the attached table.

It was prepared (Comparative Example 2) acrylic solvent type pressure-sensitive adhesive (Saiden Chemical Co., Ltd. AT-D ₁₀₎ is in the same manner as in Example 1 with the pressure-sensitive adhesive sheet for stamps except for using as an adhesive.

This pressure-sensitive adhesive sheet for stamps was particularly poor in moisture resistance and lacked suitability as a pressure-sensitive adhesive sheet for stamps. The adhesiveness of this stamp paper adhesive sheet in a low temperature environment, light resistance,
The heat resistance, moisture resistance, and punchability are shown in the attached table.

(Comparative Example 3) As a pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive (GM-2 manufactured by Asahi Chemical Synthesis Co., Ltd.)
An adhesive sheet for stamps was prepared in the same manner as in Example 1 except that 1) was used.

This pressure-sensitive adhesive sheet for stamps was particularly poor in light resistance, heat resistance and punchability, and lacked suitability as a pressure-sensitive adhesive sheet for stamps. The adhesiveness, light resistance, heat resistance, moisture resistance and punching suitability of this pressure-sensitive adhesive sheet for stamps in a low temperature environment are as shown in the attached table.

(Effect) The pressure-sensitive adhesive sheet for a stamp according to the present invention can be directly stuck without being wet when sticking, and when peeling is required,
It can be easily peeled off by adding water, and it can always be used for stable bonding even in low temperature environments, and it is satisfactory in terms of light resistance, heat resistance, moisture resistance, and punchability. there were.

Claims (1)

[Claims] 1. A pressure-sensitive adhesive sheet for printing, comprising a paper for printing having a water-soluble adhesive layer on the back side and a release paper bonded via an adhesive layer, wherein the pressure-sensitive adhesive has a glass transition temperature of less than -35 ° C. A pressure-sensitive adhesive sheet for a stamp, comprising an acrylic emulsion-type pressure-sensitive adhesive containing less than 4% of an ethylenically unsaturated carboxylic acid-containing monomer.