JPS59109571A - Remoistening adhesive-backed paper which is prevented from becoming tacky during wet heat - Google Patents

Abstract

PURPOSE:To completely prevent a remoistening adhesive-backed paper from becoming tacky during wet heat, by providing a methycellulose coating layer through a water-soluble remoistening adhesive coating layer on a base paper. CONSTITUTION:A coating layer composed of one or more water-soluble remoistening adhesives is provided on a base paper, and further a methylcellulose coating layer is provided thereon. Examples of the water-soluble remoistening adhesives are starch adhesive, PVC adhesive, dextrin adhesive, polyacrylic acid resin, polyvinyl-pyrrolidone, gum arabic, glue, etc. Methylcellulose is coated in a quantity of 0.1-5g/m<2>, pref. 0.5-1g/m<2>. When the remoistening adhesive is starch adhesive, a very small quantity of methylcellulose of as low as 0.0003g/m<2> is effective and the lower limit of methylcellulose to be coated is 0.0001g/m<2>.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rewetting adhesive paper that completely prevents stickiness during wet heat.

For more information, please refer to rewetting adhesive paper that does not cause problems such as adhesion to hot rolls even when passed through an electrophotographic copying machine or printer.Rewetting adhesive paper is made by applying a water-soluble glue to the base paper. For example, starch-based, PVA-based, polyacrylamide-based, natural gums, cellulose derivatives, polyvinyl acetate-based, and polyacid resin-based sizing agents have been conventionally used.

Attempts have been made to make copies or prints using electrophotography on re-moistened adhesive paper coated with glue and use them for labels, luggage tags, postcards for notifications of electricity bills, etc., but electrophotographic printers Since the paper is subjected to high-temperature treatment to fix the toner, the moisture contained in the paper evaporates, activating the rewetting adhesive and making it sticky, which can cause problems such as sticking to heated rolls, hot plates, etc. The present invention aims to solve these two problems, but at the same time, it is natural that this rewet adhesive paper has sufficient rewet adhesive properties (initial adhesive strength,
It is required to have performance such as having excellent equilibrium adhesive strength), not causing blocking during paper storage, and not being deteriorated by heat when the toner is fixed.

The present inventors first investigated commonly used rewet adhesives, such as starch-based, PVA-based, polyacrylamide-based, natural gums, cellulose derivatives, polyvinyl acetate-based, polyacrylic acid resin-based, etc. Select an adhesive that does not seem to exhibit heat softening properties and apply it to <70> high-quality paper at 8 g/m" (
(solid content equivalent) was applied, and various performances were compared and studied. The results are shown in Table-1.

In the present invention, starch-based rewetting adhesives include phosphorylated starch, oxidized starch, acid-treated starch, enzyme-modified starch, pregelatinized starch,
Starch ester and starch ether. Dextrin is not included in the category of starch-based rewetting adhesives because it behaves differently from these starch-based rewetting adhesives, as will be shown later.

(PVA: polyvinyl alcohol CMO: kanopoxymethylcellulose oxidized starch, acid-treated starch, enzyme-modified starch, pregelatinized starch, starch ester, starch ether are shown in Table-
The same results as with phosphorylated starch No. 1 were obtained.

(Note) Measurement method and evaluation method - Rewetting adhesiveness Apply 7 g/m'' of water to the rewetting adhesive coated surface, immediately fold it in half so that the adhesive coated surfaces are in close contact with each other, and Press with a load of 9/d. After 60 seconds (initial adhesion) and after 6 minutes (equilibrium adhesion), the adhesive surface is peeled off by hand and the paper layer is evaluated based on the state of destruction.

(Practically speaking, ◎ to ○ is required) - 40°C blocking resistance Papers are stacked in an atmosphere of 40°C and 85% RH, and 0.
After applying a pressure of 45 Kp/d for 24 hours, the peel resistance over a 1-inch width is measured and evaluated using a universal tensile tester.

(Practically speaking, ◎ to ○ is required) or higher - Adhesive resistance at 120℃ Pressure plate at 120 degrees C Peel force is measured and evaluated using a universal tensile 9 tester.

(Practically speaking, ◎ to ○ are required.) It was confirmed that this evaluation result coincides with the paper passing suitability of an actual dry type electrophotographic high-speed printer. According to the results of the upper evaluation, it was found that PVA, starch, etc. exhibited thermal adhesiveness, contrary to expectations. The reason for this is probably that even though these adhesives are not heat-adhesive, the equilibrium water content in the paper, typically 6-10%, causes the adhesive to swell and become tacky due to heat: ,it is conceivable that.

From the results of this experiment, it became clear that re-adhesive paper suitable for the purpose of the present invention could not be obtained by applying the adhesives listed in Table 1 alone.

Conventionally, it has been known to add inorganic pigments, waxes, metal soaps, fatty acids, starch powder, etc. as anti-blocking agents, but in either case, only the expected additive effect can be obtained.

That is, although the blocking resistance is improved, the rewetting adhesive strength is reduced. In particular, it is necessary to add a large amount to prevent adhesion during wet heat, which significantly reduces rewetting adhesive strength. Even if the addition ratio is varied, the heat-resistant tackiness under moist heat and the rewetting adhesive strength are in an antagonistic relationship and do not reach the level targeted by the present invention.

Therefore, the present inventors investigated PVA-based, starch-based, and
On top of the acrylamide resin coating layer, OMO, methyl cellulose, alginate sotami, which has poor rewet adhesion but excellent heat adhesion resistance, as well as inorganic filler powders such as clay, kaolin, titanium dioxide, and baryta, and starch. Based on the idea that the object of the present invention could be achieved by applying an organic powder such as a powder, the effects were investigated using various amounts of application.

In a series of these experiments, the inventors have found that by applying a certain amount of methylcellulose on top of the rewet adhesive coating, the objects of the invention can be fully achieved. , has completed the present invention.

Even if a substance that does not exhibit thermal adhesiveness other than methylcellulose mentioned above is applied on top of the rewet adhesive, the additive effect that is expected in advance, that is, the Kerr rewet adhesive strength that improves the blocking resistance to 9 is reduced. You can only get the effect of doing so. In particular, the adhesion resistance under moist heat does not reach a practical level even if the addition ratio is increased.

However, with methylcellulose alone, we found not only an additive effect, but also a synergistic effect in that even when the amount applied was increased, the rewetting adhesive strength was only slightly reduced, and the blocking resistance was greatly improved. be. In particular, it is not clear why 0-methylcellulose, which has shown a level of tackiness that is sufficiently durable for practical use when exposed to moist heat, has such performance, but it is probably due to its molecular structure (・It gels in high temperatures and is resistant to heat. Since it becomes water-insoluble, it is thought that the adhesive resistance when heated is improved.

Next, the circumstances leading to the present invention will be explained in more detail with reference to experimental examples.

<70> Apply 109A+ rewetting adhesive shown in Table 2 to high-quality paper.
19An' was applied thereon, and a heat-resistant adhesive 19An' was applied thereon.

The results of this experiment revealed that methylcellulose is highly effective.

Next, the amount of methyl cellulose applied was tested on <70> high-quality paper using the combinations shown in Table 6.

Table 3: Effect of varying the amount of methylcellulose applied (Mc: methi/ld lylerose) The anti-adhesive effect of methylcellulose during moist heat is surprisingly very small when the rewetting adhesive is starch-based. 0.000311An
It became clear that a coating amount of 0.0001 g/m was effective.The lower limit was found to be 0.0001 g/m. When the rewetting adhesive is PVA-based, methylcellulose is 0, j
~5 g/m'X preferably 05-1. ! It became clear that 7/G was an appropriate coating amount.

In addition, in the case of various rewetting adhesives other than starch-based adhesives, such as polyacrylamide-based resins, polyacrylic acid-based resins, polyvinylpyrrolidone, gum arabic, and glue, the amount of methylcellulose applied should be approximately the same as that for PVA-based adhesives. became clear.

It was revealed that the amount of methyl cellulose applied to dextrin was the same as that for the PVA type and different from that for the starch type.

As long as the object of the present invention can be achieved, two or more types of rewetting adhesives may be mixed. Further, other additives may be added to the methylcellulose coating liquid and the rewetting adhesive liquid. From an economic point of view, it is desirable that the amount of the rewetting adhesive applied to the base paper is as small as possible, taking into account the adhesive resistance under heat, as long as the rewetting adhesive strength is not impaired. Although it depends on the type of rewetting adhesive, the coating amount is usually 4 to 10 jj/m'.

The adhesive is applied to the paper using a coater such as an air knife coater, roll coater, bar coater, or blade coater, spray coating, or a gravure printing machine.

Furthermore, if the wooden pillar type j can be achieved, it is not necessary for the paper surface to be completely covered with the rewetting adhesive, and the adhesive may be applied in eight areas such as a net, dots, or checkerboard pattern.

Methylcellulose may be dissolved in an organic solvent and its mixture with water.

Example-1 <70> 7 l/m of phosphorylated starch powder aqueous solution on high-quality paper
(based on solid content) using an air knife coater, and then apply 0.0.01i of methylcellulose aqueous solution.
/m” (solid content equivalent).The obtained rewetting adhesive foam paper does not cause blocking during paper storage, and does not cause problems such as adhesion to the machine even when passed through a dry electrophotographic printer. This did not occur at all, and the rewetting adhesive strength was also excellent.

Example-2 <70> High-quality paper t completely saponified PVA aqueous solution at 7 i/m
” (solid separation! 4-) using an air knife coater, and then apply 0.5
9A" (solid fractionation It did not cause any problems and also had excellent rewetting adhesive strength.

patent applicant Tokushu Paper Co., Ltd. Representative 3 1) Jin

Claims (1)

[Scope of Claims] 1. A rewetting adhesive paper comprising a coating layer of a water-soluble rewetting adhesive alone or a mixture thereof, and a coating layer of methyl cellulose on the coating layer. 2. Claim 1, characterized in that the water-soluble rewetting adhesive is starch-based, PVA-based, dextrin, polyacrylamide-based resin, polyacrylic acid-based resin, polyvinylpyrrolidone, gum arabic, or moon ginseng. Rewetting adhesive paper as described in section. 6. If the water-soluble rewetting adhesive coating layer is made of PVA, dextrin, polyacrylamide resin, polyacrylic acid resin, polyvinylpyrrolidone, gum arabic, or moromi, either alone or in combination, the amount of methyl cellulose applied is 0.
When the rewetting adhesive paper 04 according to claim 2 is characterized in that the coating layer of the water-soluble rewetting adhesive is starch-based, the coating amount of methylcellulose is o, o
The rewetting adhesive paper according to claim 2, characterized in that the rewetting adhesive paper has a yield of 5 g/fn''.