JP2986334B2 - Pseudo adhesive paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of temporarily bonding,
The present invention relates to a pseudo adhesive sheet having a function that can be easily peeled off when necessary. More specifically, a folding pseudo-adhesive paper, an overlay pseudo-adhesion, in which an adhesive that is not normally bonded but is releasably pseudo-adhered when given conditions are applied to at least a part of one side of the support, is applied. Paper,
The present invention also relates to a pseudo-adhesive sheet suitable as an information concealing sheet having confidentiality, a confidential postcard, a confidential envelope, and the like.

[0002]

2. Description of the Related Art In recent years, while the amount of information transmitted through communication means such as communication and mail has increased, communication means requiring confidentiality such as personal information have been emphasized and demanded.

Further, with the revision of the Postal Law, postcard systems having confidentiality have been put into practical use and have begun to spread. This confidential postcard system folds a reciprocating postcard with various information such as personal information written on the inside, folds the overlapped portion, conceals the information, mails it, and sends it to the recipient. Is a system in which pseudo information is peeled off and concealment information is read. These communication methods that require confidentiality include, for example, when the company communicates with employees, and when a bank or credit company communicates confidential information with customers,
The major issues are prevention of leakage of the confidentiality information, convenience of information communication, and ease of opening.

Conventionally, a thermoplastic resin layer is provided on a support,
After printing the confidentiality information, the confidentiality has been obtained by a method in which the resin layers are opposed to each other and heated and bonded, or a method using a heat-sensitive or pressure-sensitive non-peelable adhesive. These types of methods using heat bonding, heat-sensitive or pressure-sensitive non-peelable adhesives are capable of mass processing using computers and printing machines, and are in increasing demand.

[0005] However, heating bonding, bonding with a heat-sensitive or pressure-sensitive non-peelable adhesive have the above-mentioned convenience,
There are problems such as the necessity of perforation processing in order to avoid breakage of necessary parts at the time of opening, the generation of cut pieces at the time of opening, and the inability to use the postcard system.

As a means for solving these problems, there has been proposed an information laminated body which can be mailed as a second type fixed form mail, an example of which is disclosed in Japanese Patent Application Laid-Open No. 4-59395. is there. This means that at least a part of the surface of the base sheet has a non-peelable pressure-sensitive adhesive such as a natural rubber or a synthetic rubber conventionally used in general, and a non-affinity for the adhesive base. It is formed by a so-called pseudo-adhesive paper provided with a pseudo-adhesive layer made of a fine particle filler capable of peeling.

[0007]

In a pseudo-adhesive applied to this kind of pseudo-adhesive paper, it is necessary to impart releasability by adding a fine particle filler, and it is necessary to release the pseudo-adhesive during mailing. It is also necessary to provide a predetermined adhesive force for such reasons as not to do so.

[0008] The adhesive strength of the conventional pseudo-adhesive is ensured exclusively by a pressure-sensitive adhesive, usually a rubber latex itself. To obtain the necessary adhesive strength as a pseudo-adhesive, a large amount of pressure-sensitive adhesive is required. Needed an agent. However, since rubber latex-based pressure-sensitive adhesives are relatively expensive, it is not preferable to use a large amount thereof.

Accordingly, an object of the present invention is to provide a pseudo-adhesive paper having a pseudo-adhesive layer exhibiting a necessary adhesive force without using a large amount of pressure-sensitive adhesive.

[0010]

The object of the present invention is to provide a pseudo adhesive containing a non-peelable pressure-sensitive adhesive as a basic component and a particulate filler in at least one surface of a support sheet. Is formed in the part and usually adheres
In a pseudo-adhesive paper which is pseudo -adhered releasably when applied , the non-peelable pressure-sensitive adhesive as a basic component is a latte.
Having an average molecular weight of 100 in the pseudo-adhesive.
Polyethylene glycol of about 450 to about 1 to 3 with respect to the total solid content of the pseudo adhesive layer.
This can be solved by adding 0%.

In a more preferred embodiment, the solid content of polyethylene glycol is 2 to 15% based on the total solid content of the pseudo adhesive layer, and the average molecular weight of polyethylene glycol is 190 to 210.

[0012]

It is known that an increase in the amount of the pressure-sensitive adhesive in the pseudo-adhesive results in an increase in the adhesive strength. However, since this kind of pressure-sensitive adhesive is expensive, the present invention is not applicable. The inventors have conducted intensive studies on securing the required adhesive strength of the pseudo adhesive layer without increasing the amount of the pressure-sensitive adhesive. As a result, it was found that when polyethylene glycol was added to the pressure-sensitive adhesive, the adhesive strength was improved as in the case where the amount of the pressure-sensitive adhesive was increased, and the present invention was completed.

When polyethylene glycol is added, the average molecular weight of polyethylene glycol needs to be 100 to 450, as will be shown in the examples below. preferable.

It is desirable that the solid content of polyethylene glycol in the pseudo adhesive layer is 1 to 30% based on the total solid content of the pseudo adhesive layer. If the solid content is less than 1%, the pseudo-adhesive cannot be given sufficient adhesive strength, and if it exceeds 30%,
This is because the strength of the coating layer is reduced and printing becomes difficult, and a problem that the surface is sticky occurs.

[0015]

The present invention will be described in more detail with reference to the following examples. The following is an example of the pseudo adhesive sheet according to the present invention. That is, in the folding pseudo-adhesive supply envelope shown in FIG. 1, a pseudo-adhesive layer 2 is provided on the surface of the support sheet 1, and after the supply information is printed on the pseudo-adhesive layer 2, it is shown in FIG. As described above, the information printing surface 3 is folded into two valleys on the inner surface from the center line in the printing surface printing direction, and is pressure-bonded. Address information 4 and the like are printed on the back surface.

In the tri-fold postcard shown in FIG. 2, pseudo adhesive layers 2 and 2 are formed on the front and back surfaces of the support sheet 1, and concealment information, communication information, and address information 4 are printed on the front surface thereof. )
As shown in the figure, folding and pressure bonding are performed so that the address printing surface is the front surface.

The two-fold postcard shown in FIG. 3 and the partially folded postcard shown in FIG. 4 form a pseudo-adhesive layer 2 on the inner side of the fold of the support sheet 1, print information, fold and press. Adhesive, all of which are pseudo adhesive layer 2
These are overlapped with each other and pressure-bonded.

[0018] In addition to the uses listed in these examples, it is widely and suitably used for various postcards, postcards, reports, and the like. It is also possible to facilitate re-peeling by providing a non-coated portion. The pseudo-adhesive paper of the present invention is suitably applied as a foldable pseudo-adhesive paper, a superimposed pseudo-adhesive paper, an information concealing paper having a confidential property, a confidential postcard, a confidential envelope, and the like.

[0019] As non-peelable pressure-sensitive adhesives used in the present invention, the latex, specifically natural rubber, optionally from among those used in the conventional normal pressure sensitive adhesive such as a synthetic rubber Although it can be selectively used, particularly natural rubber latex obtained by subjecting natural rubber to sulfur-free vulcanization and natural rubber latex mixed with methyl methacrylate, graft polymerization of methyl methacrylate onto natural rubber, Acrylic-modified rubber latex, or a mixture of rubber latex and a protective colloid-based acrylic copolymer emulsion, are preferred in terms of blocking resistance, deterioration over time, ink adhesion, and the like.

Further, the pseudo-adhesive layer in this embodiment preferably contains, as fine particle fillers, fine particle fillers having a buffering effect against pressure and fine particle fillers having no buffering effect. ing. The fine particle filler having a buffering effect against pressurization changes its shape when an external pressure is applied, so that when an external pressure is applied to the pseudo-adhesive layer, irregularities on the surface of the pseudo-adhesive layer are reduced. For this reason, the contact area between the pressure-sensitive adhesives is increased, and the effect of further increasing the adhesive force of the pseudo-adhesive layer is exhibited, but on the other hand, the pseudo-adhesive paper cannot be peeled off or characters printed on the support sheet are used. This can cause problems such as blocking of the image.

Therefore, a fine particle filler having no buffering effect against pressurization is also added to the base. Since the amount of deformation of the fine particle filler having no buffer effect against pressurization is small even when an external pressure is applied, the surface roughness of the pseudo-adhesive layer to which the fine particle filler is added and the bonding area between the adhesives Is limited to the change amount of the fine particle filler having a buffer effect, and does not change any more. Therefore, even when the external pressure increases, the improvement of the adhesive force can be suppressed.

A pseudo-adhesive is formed by adding a fine particle filler having a buffering effect to pressure and a fine particle filler having no buffering effect to a pressure-sensitive adhesive, and the amounts of these added are appropriately adjusted. By doing so, it is possible to prevent the pseudo-adhesive layer from rising only up to a certain upper limit. Therefore, by performing pressure bonding with a relatively large pressure at the time of pressure bonding, the problem of peeling of the bonded surface at the time of transportation when used as information concealment paper or the like is solved, while the bonding force of the pseudo-adhesive layer is reduced. ,
Since the adhesive strength does not exceed a certain level, the above-mentioned problems such as non-peelability and blocking do not occur.

These fine particle fillers differ in particle diameter and specific surface area between those having a buffering effect and those having no buffering effect. Therefore, even when external pressure is applied to the pseudo-adhesive layer, since the fine particle fillers having different particle diameters are added, the unevenness of the surface of the pseudo-adhesive layer is prevented from being uniformly changed by the external pressure, and the pseudo-adhesion is prevented. Variations in the adhesive strength of the agent layer can be suppressed. On the other hand, for fine particle fillers having different specific surface areas, since the amount of pressure-sensitive adhesive adhered to the surface is different, the adhesive force and peeling force of the pseudo adhesive layer can be adjusted in a fine region. .

Further, as a fine particle filler having no buffering effect, a large number of needle-like projections are radially present on the surface to form a primary or secondary aggregate having an average particle diameter of 1 to 5 μm. Use of calcite-based precipitated calcium carbonate or aragonite-based precipitated calcium carbonate having a large number of needle-like projections radially on its surface and forming secondary aggregates having an average particle diameter of 1 to 5 μm. Thereby, a stable adhesive strength can be obtained.

The calcite-based primary or secondary aggregated calcium carbonate or the aragonite-based secondary aggregated calcium carbonate having the above-mentioned shape makes it easier for the pressure-sensitive adhesive to adhere to the surface because of its shape. Holds the adhesive easily. Further, since the aggregate has a crystal structure having a shape in which a large number of needle-like projections are radially present, the gap between the adhesive surface layers can be maintained at the diameter of the aggregate when pressed. Therefore, when such precipitated calcium carbonate is used, it is easy to adjust the adhesive force of the pseudo-adhesive, and it is also possible to minimize the required amount of the pressure-sensitive adhesive. When the average particle size is less than 1 μm, no non-buffering effect is exhibited, while when it exceeds 5 μm, the pseudo-adhesive strength is reduced.

Among these fine particle fillers, styrene beads, cereal starch, modified starch, synthetic fine particle silica, calcium carbonate, and the like can be mentioned as the fine particle filler having a buffering effect against pressurization. Grain starch and synthetic fine-particle silica can be used for this purpose. Since cereal starch does not have a porous surface, the amount of pressure-sensitive adhesive adhered is small, the particle size is equal to or larger than that of secondary aggregated calcium carbonate, and the particle itself has elasticity. In addition to being easy, the amount of the pressure-sensitive adhesive attached is small, so that blocking can be prevented and a paper-like feel can be obtained. As cereal starch, the particle size is 1-30μ
m, preferably 5 to 20 μm can be suitably used. Here, the calcium carbonate refers to calcium carbonate other than the primary or secondary aggregated calcium carbonate having no buffer effect.

Further, by using a modified PVA having an affinity for both the pressure-sensitive adhesive and the fine particle filler in the pseudo adhesive layer, the adhesive force of the pseudo adhesive layer can be more accurately adjusted. can do. Examples of the modified PVA having an affinity for both the pressure-sensitive adhesive and the fine particle filler include carboxyl group-modified PVA and sulfone group-modified PVA.
A, acetoacetyl group-modified PVA, cationic group (quaternary ammonium salt) -modified PVA, and silicon-group-modified PVA can be used, and silicon-group-modified PVA is particularly preferable.
Silicon-modified PVA has a remarkable interaction with various inorganic fine particle fillers, and in particular, forms a chemical bond, so that when forming a pseudo-adhesive layer, it has excellent film forming properties with the fine particle filler,
The coating is transparent, tough, and has excellent barrier properties, so it has a high affinity with the pressure-sensitive adhesive, prevents deterioration of the pressure-sensitive adhesive with time, improves printability, and transfers information to the opposing surface. The printed surface does not become dirty.

The composition of the pseudo-adhesive layer is as follows.
10 to 60 parts, more preferably 20 to 5 parts, of the fine particle filler having a non-buffering property against pressure is added to 100 parts by weight.
0 parts by weight, 10 to 250 parts by weight, more preferably 50 to 150 parts by weight of the fine particle filler having a buffering property against pressure, and 2 to 30 parts by weight of the modified PVA, more preferably 5 to 5 parts by weight.
The ratio is desirably 20 parts by weight, and the thickness of the pseudo adhesive layer is desirably 5 to 20 μm.

If the compounding amount of the fine particle filler is less than the above range, a problem of blocking may occur and peeling may be impossible or difficult. In particular, when the amount of the fine particle filler having a buffering effect against the pressurization is small, the problem is remarkable. On the other hand, if it exceeds the above range, the adhesive strength of the pseudo-adhesive layer is inferior and peeling tends to occur. In the pseudo-adhesive layer used in the pseudo-adhesive paper of the present invention, it is important to appropriately select the mixing ratio of the pressure-sensitive adhesive, the fine particle filler, and the modified PVA.

The pseudo-adhesive layer is coated with a vent blade, a comma, a lip, an air knife or the like to obtain a uniform pseudo-adhesion surface and printability. It is preferable to apply a pressure of 10 kg / cm ² to flatten excessive protrusion of the pseudo adhesive surface.

The support sheet used in the present invention is not particularly limited, and various types of paper such as high quality paper mainly composed of cellulose fibers and various synthetic papers can be used.

<Experimental Example> Next, an experimental example of the pseudo adhesive sheet according to the present invention will be described. (Experimental Example 1) As a pressure-sensitive adhesive, natural rubber latex obtained by sulfur-free vulcanization of natural rubber and mixing with methyl methacrylate was used, and a particulate filler, a waterproofing agent, and the like were added to the pressure-sensitive adhesive. ,
A sample to which polyethylene glycol (hereinafter abbreviated as PEG) having a solid content of 100% is added (sample 1);
Pseudo-adhesives each made of a sample to which PEG was not added (sample 2) were produced, and these pseudo-adhesives were applied to a support sheet, and the two types of pseudo-adhesive papers on which the pseudo-adhesive layers were formed were evaluated. The adhesive strength was compared.

The measurement of the adhesive strength was performed as follows. Each of the samples on which the pseudo adhesive layer was formed was placed at 20 ° C. for 6 hours.
After curing for 24 hours in an environment of 5 RH, the pressure of the dry sealer was adjusted to 50 kg / cm ² , and pseudo-adhesion was performed, and the peel strength of a 25 mmφ sample was measured at a head speed of 300 mm / min.

As a result of the measurement, the adhesive strength of the support sheet having the pseudo adhesive layer formed on Sample 1 was larger than the adhesive strength of the support sheet having the pseudo adhesive layer formed on Sample 2. From these results, it was found that the addition of PEG improved the adhesive strength.

(Experimental Example 2) Next, a fine particle filler and the like were added to the same pressure-sensitive adhesive used in Experimental Example 1, and the average molecular weight of PEG added to this pressure-sensitive adhesive was determined. Experiments were conducted in which pseudo-adhesives were produced by appropriately adjusting the amount of solids added, and the adhesion strength of each of the support sheets on which the pseudo-adhesive layers were formed with these pseudo-adhesives was measured. The measurement of the adhesive strength was performed by the same method as in Experiment 1. Table 1 shows the average molecular weight of PEG, the amount of solids added, and the experimental results.

[0036]

[Table 1]

As is clear from Table 1, the PEG added was
Is in the range of 100 to 450, particularly 190
When the value was in the range of ~ 210, the adhesive strength of the pseudo adhesive was improved. Also, when the solid content exceeds 30%, it was found that although the adhesive strength was not inferior, the strength of the coating layer was reduced and the surface of the pseudo-adhesive layer was sticky.

[0038]

As described above in detail, according to the present invention, it is possible to provide at least the necessary adhesive force to the pseudo-adhesive layer of the pseudo-adhesive paper without using a large amount of pressure-sensitive adhesive. Become.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a folded pay envelope.

FIG. 2 is an explanatory diagram of a tri-fold postcard.

FIG. 3 is an explanatory diagram of a two-fold postcard.

FIG. 4 is an explanatory diagram of a partially folded postcard.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Support sheet, 2 ... Pseudo adhesive layer, 3 ... Information printing surface, 4 ... Address information.

Continuation of front page (72) Inventor Nobuo Yamamoto 5-1 Kamiyacho, Iyo Mishima City, Ehime Prefecture Daio Paper Co., Ltd. (56) References JP-A-62-127377 (JP, A) JP-A-4-306278 ( JP, A) JP 47-51808 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) C09J 7/00-7/04 B42D 15/02

Claims (1)

(57) [Claims] The method according to claim 1] non-releasable pressure sensitive adhesive to the base of a basic component, a layer of pseudo-adhesive particulate filler is contained is formed on a part of at least one surface of the support sheet, in a normal
Pseudo-adhesive so that it can be peeled off when given conditions are applied without bonding
In the pseudo adhesive paper, the non-peelable pressure-sensitive adhesive as a basic component is a latex.
And the average molecular weight in the pseudo adhesive 100-45
A quasi-adhesive paper, wherein 0 polyethylene glycol is added as a solid content of 1 to 30% based on the total solid content of the quasi-adhesive layer.