Stock material or miscellaneous articles – Layer or component removable to expose adhesive
Reexamination Certificate
2000-08-24
2003-07-22
Ahmad, Nasser (Department: 1772)
Stock material or miscellaneous articles
Layer or component removable to expose adhesive
C428S041600, C428S041700, C428S041800, C428S537500, C428S913000, C503S226000
Reexamination Certificate
active
06596358
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thermally sensitive recording type adhesive label to the reverse side of which an adhesive layer and a release paper are arranged.
2. Description of the Prior Art
In general, a thermally sensitive recording paper prepared by forming a thermally sensitive recording layer mainly containing a colorless or pale colored basic colorless dye and a color developer that makes said basic colorless dye develop color by heat on a sheet type substrate is well known. And a thermally sensitive recording type adhesive label to the reverse side of which an adhesive layer and a release paper are prepared is proposed to be used for a thermally sensitive recording type label for wrapping or a POS label for foods used at super markets. In a case of above mentioned thermally sensitive recording type adhesive label, compared with the conventional printing methods that use ink or an ink ribbon, since the printing is carried out by a thermal head, this type has an advantage that printing is more easily and that the printed image is more beautiful.
However, this kind of thermally sensitive recording type adhesive label has a problem that when is wetted by water or when is placed in a high humid condition, said thermally sensitive recording type adhesive label swells by absorbed water and the adhesive layer is easily scaled off from the substrate, because, generally a substrate and the surface of an adhesive layer are hydrophilic. As the substrate which has good water resistance, a base paper for diazo photo sensitive paper has high sized and lower pH is well known, however, said paper becomes transparent when water is stuck and the readout of a barcode becomes difficult. Therefore, to avoid said problem, it is necessary to take a countermeasure, for example, that titanium di-oxide is added in an adhesive layer.
Meanwhile, in the field of the thermally sensitive recording paper, it is well known to use a neutral paper as a substrate. However, if a neutral paper is used as the substrate of the thermally sensitive recording type adhesive label, the tendency that it deteriorates the adhesive strength of an adhesive layer is usually obserbed.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to provide a thermally sensitive recording type adhesive label which has high printing density and has good brightness and preservability of background color, further does not cause the scaling off of an adhesive layer when is wetted by water or when is exposed in high humid condition.
The inventor of this invention has carried out an intensive study to dissolve the above-mentioned problem, and accomplished the thermally sensitive recording type adhesive label of this invention. That is, the present invention is a thermally sensitive recording type adhesive label possessing a thermally sensitive recording layer on a substrate, and an adhesive layer and a release paper on the reverse side of the substrate, wherein said substrate is a neutral paper containing a wet strength reinforcing agent and further containing 5-20 wt. % of a filler to the total weight of pulp.
The present invention is accomplished by finding out that the above-mentioned construction of a thermally sensitive recording type adhesive label can dissolve the problems. A diazo base paper has a good water resistance, however, when it is used as a substrate, the background color and the background color preservability of thermally sensitive recording type adhesive label are easily deteriorated. Since the property of the diazo base paper is acidic, said problem deems to be caused by the deterioration or the affection of the components which consist in the thermally sensitive recording layer.
Further, the important point of the neutral paper used in this invention is that it contains a wet strength reinforcing agent. When filler is contained, since said filler absorbs the wet strength reinforcing agent, the desired wet strength can not be obtained. Therefore, not withstanding an acidic paper or a neutral paper, in a case of paper manufacturing process using a wet strength reinforcing agent, it is ordinary to manufacture a paper without filler or controlling the content of filler as a solid less than 4 wt. % of pulp. This is also same in a case of the diazo base paper. On the contrary, in the case of the neutral paper used in this invention, it is effective to contain a filler as a solid by 5-20 wt. % to the of pulp. By containing a filler by said limit, the excellent color developing sensitivity can be obtained keeping the sufficient paper strength as face stock the thermally sensitive recording type adhesive label, further the problem of becoming transparent when wetted by water can be avoided. More desirable limit of the content of a filler is 7-15%.
In the present invention, when a neutral paper is used as the substrate, the deterioration of adhering strength of an adhesive layer can be avoided. The reason why is still unclear, however, it is surmised that the deterioration of adhering strength is caused by the reaction between adhesive agent and calcium ions contained in the neutral paper. And, in a case of this invention, it is surmised that the presence of the wet strength reinforcing agent gives some effects, and above mentioned reaction can be effectively controlled.
DETAILED DESCRIPTION OF THE INVENTION
At the manufacturing of the neutral paper used in this invention, a kind of wet strength reinforcing agent to be used is not restricted, for example, urea resin, melamine resin, urea-formaldehyde resin, melamine-formaldehyde resin, polyamide-polyurea-formaldehyde resin, polyamide resin, polyamide-epichlorohydrin resin, polyamide-polyamine-epichlorohydrin resin, epoxidized polyamide resin, polyethylene-imine resin, aldehyde starch or ketone aldehyde resin can be used. More than two kinds of these compounds can be used in combination as occasion demands. Especially, among these compounds, polyamide-epichlorohydrin resin and polyamide-polyamine-epichlorohydrin resin are desirably used.
When the content of wet strength reinforcing agent is too small, the sufficient water resistance cannot be obtained, and when the content of wet strength reinforcing agent is too much, the problems such as pitch trouble or press stain are frequently caused. Therefore, the desirable containing amount of the wet strength reinforcing agent as a solid is 0.3-1.0 wt. % of pulp. In the present invention, by containing the wet strength reinforcing agent by said limit, the desired water resistance can effectively be obtained without hurting the productivity. More desirable limit of the content of wet strength reinforcing agent is 0.3-0.5 wt. %.
Further, as a filler, any kinds of fillers such as clay, talk, calcium carbonate or titanium dioxide can be used, and among these mentioned fillers, calcium carbonate is desirably used.
As the pulp used for the manufacturing of a base paper, NBKP, LBKP, NBSP, LBSP, CGP, GP, recycled paper pulp or various kinds of non-wooden pulps can be mentioned.
In the neutral paper used in this invention, alkyl ketene dimmer, alkenyl succinic acid anhydride, petroleum resins, styrene resins and higher alcohols can be used as the neutral sizing agent, and among these, alkyl ketene dimmer is desirably used. The amount of the neutral sizing agent to be added is as a solid 0.05-1.5 wt. % of pulp. As the fixing agent for these neutral sizing agent, aluminum sulfate, polyamide, acrylamide or cationic starch can be used. As a size press solution, starch, PVA, alkyl ketene dimmer, alkenyl succinic acid anhydride, petroleum resins or styrene resins can be used, and these compounds can be used alone or can be used in combination. Further, a water resistance agent such as glyoxal can be used as occasion demands.
As a material for an adhesive layer formed between the reverse side of the substrate and the release paper of this invention, the conventional materials which are used ordinary in the label preparation process can be used.
In the present invention, t
Kimura Yoshihide
Ogawa Hidenori
Sakamoto Tastuhiko
Sumikawa Naomi
Ahmad Nasser
Nippon Paper Industries Co Ltd
Sherman & Shalloway
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