JP3710855B2 - Pressure sensitive adhesive sheet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention, confidential postcard, direct mail, notice, pamphlet, is used in the lottery and the like, temporarily related to the pressure-sensitive adhesive sheet can be visually recognized inside information when peeling off the temporary adhesive and bonding surfaces, especially temporary adhesive scheduled surface relates to pressure-sensitive adhesive sheet printing gloss, such as photographic images is requested is made.
[0002]
[Prior art]
In recent years, confidential postcards, direct mails, and the like that can be viewed inside when peeled open are widespread in terms of information security and a large amount of information.
For example, when folding a postcard paper that is twice the size of a postcard with the information-written side inside, the two transparent thermoplastic resin films are peelably bonded to each other and a pressure-sensitive adhesive layer is applied to both sides. A postcard is inserted between re-peelable resin sheets. At the time of peeling, it is peeled off at the joint surface between the resin films, and information can be visually recognized through the resin film. In this form, the re-peelable resin sheet is expensive and cumbersome to insert. However, since it is possible to print the entire image information or the like, it is frequently used in direct mails such as product advertisements.
[0003]
Before information is written, a re-peelable adhesive layer is preliminarily formed on the surface to be temporarily bonded, and a letter or the like is folded on the adhesive layer after printing with a non-impact printer (NIP) or the like. Such re-peelable adhesive sheets are also frequently used in applications that mainly require security such as usage details. As such an adhesive sheet, there is a pressure-sensitive adhesive sheet in which a re-peelable pressure-sensitive adhesive layer having printability is applied to a substrate. Such a re-peelable pressure-sensitive adhesive layer is generally formed by applying an ordinary pressure-sensitive adhesive such as natural rubber latex that cannot be re-peeled, that is, a non-peelable pressure-sensitive adhesive to which a filler such as silica or starch is added. Is. The filler lowers the tackiness before bonding, enables peeling after bonding, and gives printability to the joint surface, blocking resistance, and the like. The pressure-sensitive adhesive sheet has the advantage of lower cost than the removable resin sheet.
[0004]
[Problems to be solved by the invention]
However, especially in applications where there are many photographic tones such as direct mail that are offset printed in full color on the entire surface to be bonded, the ink layer formed on the re-peelable adhesive layer has insufficient adhesive strength on the bonding surface, In addition, the pressure-sensitive adhesive sheet is inexpensive but not optimal due to poor gloss and low image quality. In addition, even if low image quality is acceptable, it is necessary to avoid the peripheral portion of the surface to be temporarily bonded for the pattern portion, and to avoid a similar pattern with a large amount of ink adhering to the surface to be bonded even at the center portion. There are layout restrictions. For this reason, conventionally, in the application for printing photo-like image information such as direct mail, the above-mentioned re-peelable resin sheet, which has no restrictions on the printing area even at high cost and does not affect the adhesiveness of temporary adhesion, is often used. Has been.
[0005]
Therefore, as a result of diligent research on pressure-sensitive adhesive sheets with an inexpensive coating-forming type re-peelable pressure-sensitive adhesive layer that has no restrictions on the printing area, the present inventor obtained information by printing and re-peelable pressure-sensitive adhesive sheets. It is found that it is more preferable if a re-peelable pressure-sensitive adhesive layer mainly composed of a pressure-sensitive adhesive main agent and a filler, which have good adhesion to printing ink, is formed on the face to be temporarily bonded. ing.
Instead of the conventional natural rubber (NR) system, such an adhesive is made of acrylonitrile-butadiene rubber (NBR) system latex that has adhesion to printing ink and gravure coating suitability, and blocking as a filler. Polystyrene particles are used for the purpose of prevention.
[0006]
Conventionally used NR-based pressure-sensitive adhesives are preferable in that they are excellent in self-adhesiveness and have low dry tack, but are extremely inferior in gravure coating suitability and poor in adhesion to printing ink. The gravure coating suitability is desired because it is useful as a means for partially forming the re-peelable adhesive layer. For example, conventional pressure-sensitive adhesive sheets are generally coated as a surface treatment for paper, including surfaces other than those that are to be temporarily bonded, even when tri-folding, for example, and formation on unnecessary parts is useless. This is because it is desirable to provide a re-peelable pressure-sensitive adhesive layer only at necessary portions. In addition, NR-based adhesives are prone to oxidative deterioration, and handling of pressure-sensitive adhesive sheets is difficult to use, such as when plastic packaging is required except for use from the point of quality control when handling users. . Therefore, also in this respect, the advantage of using the NBR-based pressure-sensitive adhesive or the like has been found to be easy to use.
[0007]
By the way, generally, those having a glass transition temperature Tg of room temperature (25 ° C.) or lower have high tackiness and exhibit extremely high adhesiveness over time. Incidentally, the NBR adhesive has a Tg of about −20 ° C. Therefore, in the re-peelable pressure-sensitive adhesive layer using the NBR-based pressure-sensitive adhesive, even if the adhesive strength is such that it can be easily peeled off immediately after being pressed, the adhesive strength increases after about one month, There is a case where the material is destroyed by the base material or the ink layer without peeling. This problem can be remedied by using silica, starch, or the like, which is a filler used for adhesive strength adjustment in the conventional NR system, but the re-peelable adhesive layer is whitened, and the printed characters and This is not preferable because the quality of the pattern is impaired.
[0008]
Therefore, the present invention provides a pressure-sensitive adhesive sheet having a temporary adhesion planned surface that faces by folding in half, and the temporary adhesion planned surface is required to have a glossy feeling such as a photographic image, and the adhesive strength of the temporary adhesion planned surface over time. It is an object to provide a pressure-sensitive adhesive sheet that is excellent in mechanical stability and inexpensive .
[0009]
[Means for Solving the Problems]
The above object is achieved by the present invention described below.
That is, the invention of claim 1, have a temporary adhesive scheduled surface facing by folio, on one surface of the temporary bonding scheduled surfaces facing during temporary adhesion only, after bonding front and peeling the normal state in not adhere, in pressure-sensitive adhesive sheet which the removable pressure-sensitive layer that be bonded by at least pressure is applied and formed, the removable pressure-sensitive layer has a transparency comprising a filler made of resin particles in the adhesive base material It is a re-peelable pressure-sensitive adhesive layer, and a transparent overprint layer made of an ultraviolet curable resin is formed on the other surface of the temporary adhesion planned surface. At the time of peeling, the re-peelable pressure-sensitive adhesive layer and the overprint layer are It is a pressure-sensitive adhesive sheet characterized by peeling between the two.
The invention of claim 2 of the present application is characterized in that, in claim 1, the adhesive main agent is an adhesive main agent selected from the group of styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex and acrylic resin latex. It is a pressure sensitive adhesive sheet.
The invention of claim 3 of the present application is the pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the filler contains one or both of polystyrene particles and polymethyl methacrylate particles .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the pressure-sensitive adhesive sheet of the present invention will be described in detail with reference to the drawings.
First, FIG. 1 is a plan view showing a folded postcard paper 10 as an embodiment of the pressure-sensitive adhesive sheet of the present invention, and FIG. 2 is a sectional view of the postcard paper 10 of FIG. 3 is a rear view of the postcard paper 10 of FIG. 1, and FIG. 4 is a cross-sectional view of the postcard paper 10 of FIG.
The postcard paper 10 shown in these drawings is composed of a first sheet 11 and a second sheet 12 of the same size divided by a central folding line, and visible information 3a and 3b are formed as visible information 3 on each sheet, respectively. . On the base material 1 of the first sheet 11, visible information 3 a is formed by printing while leaving the peripheral portion, and the first sheet base material 1 including the visible information 3 a as a temporary adhesion scheduled surface of the first sheet is formed. A transparent releasable pressure-sensitive adhesive layer 2 is formed on the entire surface by coating. Further, visible information 3b by printing is formed on the base material 1 of the second sheet 12 while leaving the peripheral edge thereof, and the base material of the second sheet including the visible information 3b as a temporary adhesion scheduled surface of the second sheet An overprint layer 4 made of a transparent ultraviolet curable resin is formed on the entire surface of 1. In addition, leaving the peripheral part also has the meaning which makes visible information 3a and 3b formed in the 1st sheet | seat 11 and the 2nd sheet | seat 12 distinguishable with respect to these sheets on drawing, and visible information is these It may be formed over the entire surface of the sheet.
[0011]
Further, as shown in FIG. 3, the back side of the postcard paper 10 has a destination column on the first sheet 11 side in this embodiment. And as shown in FIG. 4, the surface which faces at the time of adhesion | attachment as a temporary attachment plan surface is the whole surface of the 1st sheet | seat 11, and the whole surface of the 2nd sheet | seat. Then, when the folded folded postcard 20 is peeled off, it is peeled off from the joint surface S where the re-peelable pressure-sensitive adhesive layer 2 and the overprint layer 4 are in contact.
[0012]
In addition, when the pressure-sensitive adhesive sheet of the present invention is used as, for example, a postcard sheet, in addition to the above-described two-fold type, a Z-fold type, a three-fold type, a four-fold type, or It consists of a first sheet of a size and a second sheet smaller than the first sheet, and can take various conventionally known forms such as a half-fold type that forms a postcard when the folding line 5 is folded. Further, the folding line is not limited to the vertical direction of the postcard but may be the horizontal direction. Further, a type in which a plurality of sheets are stacked without folding one sheet may be used. In addition, the application is not limited to postcard sheets such as direct mail and confidential postcards, but can be used for sheets for various uses such as pamphlets, notices, and lotteries. Further, it may be a continuous form having a marginal portion in which a large number of marginal holes are continuously provided and one unit of a plurality of sheets is continuous, or a sheet for exclusive use with a cut sheet printer.
In addition, by a conventionally known method, a release layer is provided on the surface of the re-peelable pressure-sensitive adhesive layer such as a part of the peripheral portion with an ink or the like. It is also possible to create a trigger for peeling when the corner of one sheet to be cut is cut.
[0013]
As the substrate 1 of the pressure-sensitive adhesive sheet of the present invention, conventionally known papers such as NIP (non-impact printer) paper that can form visible information by printing, synthetic paper, polypropylene resin, cellulose resin, Resin films such as polyester resins and vinyl chloride resins, nonwoven fabrics, and composites thereof can be used.
[0014]
The visible information 3 of the present invention is formed not on the re-peelable pressure-sensitive adhesive layer but on the substrate, and the re-peelable pressure-sensitive adhesive layer or overprint layer is formed on the visible information 3. Further, it is usually formed as an ink layer by printing. In particular, the pressure-sensitive adhesive sheet of the present invention does not affect the temporary adhesive force even if normal color printing such as offset printing is applied not only to a printer or the like, but also to the entire surface of the temporary bonding scheduled surface. The visible information 3 may be formed by printing means such as gravure printing, letterpress printing, flexographic printing, silk screen printing, electrophotographic printing, and ink jet printing. The printing ink used may be offset ink, gravure ink, ultraviolet curable offset ink, or the like.
[0015]
The visible information 3 is arbitrary as a character, a symbol, a figure, a pattern, a photographic image, and the like. In particular, even if the color image information is formed by process color offset printing or the like, there is no decrease in temporary adhesive force. Further, since the visible information 3 is formed before the formation of the re-peelable pressure-sensitive adhesive layer or the overprint layer, fixed information such as a product description is suitable.
[0016]
The re-peelable pressure-sensitive adhesive layer 2 is transparent so that the visible information 3 below is at least visually recognizable, is not sticky before and after being peeled off, and does not adhere to other things in a normal state. When necessary, it adheres to the overprint layer 4 by using heat, and at the time of peeling, the interface (bonding surface) between the re-peelable pressure-sensitive adhesive layer 3 and the overprint layer 4 becomes the peeling surface S, and printing is performed thereunder. The re-peelable pressure-sensitive adhesive layer may be any layer that can be peeled off so as to remain on the coated substrate side even if there is visible information 3. If the re-peelable pressure-sensitive adhesive layer has a moderate performance, it is possible to use a conventionally known NR-based pressure-sensitive adhesive as the main adhesive and add silica or starch to such an extent that the transparency is not hindered. Although the thing which adjusted etc. may be sufficient, the following is superior.
[0017]
That is, as a preferable adhesive main agent, styrene-butadiene rubber (SBR) or acrylonitrile-butadiene rubber (NBR) rubber latex obtained by soap-free emulsion polymerization, or acrylic resin latex such as polyacrylate is used. . These exhibit excellent pressure-sensitive adhesion and strong adhesion to printing ink. The latex by the soap-free emulsion polymerization method is preferable in that it does not contain a low molecular weight emulsifier and therefore has low dry tack (stickiness). Further, these latex emulsions can use isopropyl alcohol as an antifoaming agent, and can adjust the solid content of the coating solution to an arbitrary ratio, and are excellent in gravure coating suitability. And the adhesiveness to the printing ink which forms the visible information of a lower layer is also excellent.
[0018]
In addition, as an adhesive main agent, as a latex by usual emulsion polymerization, styrene-butadiene rubber (SBR), carboxy-modified SBR (XSBR), acrylonitrile-butadiene rubber (NBR), acrylic-modified natural rubber (PMMA-NR), poly An acrylic resin latex adhesive such as an acrylic ester may be used in combination for improving various properties.
[0019]
The re-peelable pressure-sensitive adhesive layer can achieve a certain level of performance even with a soap-free emulsion polymerization latex alone, but if a filler is added to suppress the adhesive strength as in the past, the adhesive strength can be easily adjusted and the adhesive strength increases with time. It is suppressed that it becomes too much. As the filler, for example, polystyrene resin particles having an average particle diameter of about 3 to 10 μm can be used. Polystyrene resin particles, in combination with the soap-free emulsion polymerization latex, provide a re-peelable adhesive layer with well-adjusted adhesive strength.
Further, when inorganic particles such as silica and organic particles such as starch are used in combination, the surface of the re-peelable pressure-sensitive adhesive layer can be roughened to improve the silicone oil absorbability, printing suitability, stamp suitability, and the like.
As the filler, conventionally known silica, starch and the like can be used without using together with the resin particles as long as the transparency is not impaired.
[0020]
The blending amount of the filler is, for example, 5 to 20 parts by weight per 100 parts by weight of the adhesive main agent in resin particles such as polystyrene. Silica, starch, and the like are used within a range that does not hinder the transparency of the releasable adhesive layer. In addition, a compounding quantity is suitably adjusted with the dry tack of an adhesive main ingredient, and the target physical property.
[0021]
In the re-peelable pressure-sensitive adhesive layer, since the adhesive main agent is usually supplied in an emulsion, a coating liquid obtained by appropriately adding a desired filler or other additive to the adhesive is known in the art such as gravure coating and air knife coating. The coating means is formed by coating on a base material.
[0022]
The overprint layer 4 is formed by printing or coating means, and uses a conventionally known overprint ink for offset printing, a coating liquid for gravure coating, or the like. The overprint layer is a transparent resin layer and may be a thermosetting resin, but an ultraviolet curable resin is preferable in terms of easy control of the peel force and workability when manufacturing a pressure-sensitive adhesive sheet. Further, the overprint layer made of an ultraviolet curable resin or the like may contain wax, silicone, or the like, and may adjust the peeling force by reducing the adhesive force.
[0023]
The formation surface of the removable pressure-sensitive layer and the overprint layer is minimal, Ru adhesion scheduled surface der. In particular, the re-peelable pressure-sensitive adhesive layer and overprint layer of the present invention can be formed by partially forming only necessary portions of the substrate, thereby reducing waste and further reducing the cost.
[0024]
Further, in the pressure-sensitive adhesive sheet of the present invention, the surface of the re-peelable pressure-sensitive adhesive layer may have printability, and visible information such as characters may be printed on the re-peelable pressure-sensitive adhesive layer. The printability can be achieved by mixing a filler such as silica to roughen the surface.
[0025]
【Example】
NIP high-quality paper (manufactured by Nippon Paper Industries Co., Ltd., MC-M <90>) is used as the base material for the two-fold postcard paper, and UV curing is applied to almost the entire surface on the surface side that will be temporarily bonded to this paper. Visible information consisting of photographic images in the process color of the mold ink was formed by offset printing. Next, a re-peelable pressure-sensitive adhesive having the following composition was applied to the half side of the temporary adhesion planned surface by a gravure coater to form a re-peelable pressure-sensitive adhesive layer having a dry coating weight of 3 g / m2. On the other half side, an overprint layer was formed by offset printing with an overprinting ink made of a transparent ultraviolet curable resin to obtain a pressure-sensitive adhesive sheet of the present invention. Next, this pressure-sensitive adhesive sheet was folded at the center to be folded in half, the surfaces to be bonded were opposed to each other, and temporarily bonded with a mail sealer (manufactured by Dai Nippon Printing Co., Ltd., MS-9000). After temporary adhesion, after leaving at room temperature for 7 days, when peeled, the interface between the re-peelable pressure-sensitive adhesive layer and the overprint layer, including the visible information formation area, can be easily peeled off with a peeling force that is neither extremely strong nor weak It was possible to peel off.
[0026]
Re-peelable adhesive Adhesive agent: Soap-free emulsion polymerization NBR latex 100 parts by weight (manufactured by Nippon Zeon Co., Ltd., SX1503, solid content 43%)
Filler: Polystyrene particles (average particle size 7 μm) 8 parts by weight (manufactured by Soken Chemical Co., Ltd., MR-7G)
92 parts by weight of isopropyl alcohol (adhesive main agent is a part by weight including solvent)
[0027]
【The invention's effect】
According to the pressure-sensitive adhesive sheet of the present invention, since the resin particles are included as the filler of the re-peelable pressure-sensitive adhesive layer to be applied to one surface of the temporary adhesion planned surface, the conventional filler made of silica, starch or the like As a result, a re-peelable pressure-sensitive adhesive layer having transparency as compared with the one used alone is obtained. In addition, a transparent overprint layer made of an ultraviolet curable resin is formed on the other surface of the temporary adhesion planned surface.
The pressure sensitive adhesive sheet of the above, the present invention is sensitive to form the so having a removable pressure-sensitive layer and the overprint layer both transparency indicia Surijo paper gloss feeling such as full-color photographic images is requested There is an effect that it is suitable as a pressure-sensitive adhesive sheet.
In addition, the pressure-sensitive adhesive sheet of the present invention has an effect that the peeling force (adhesive force) at the time of peeling after temporary bonding is stable over time, so that it does not become difficult to peel off after a long period of time.
In addition, the pressure-sensitive adhesive sheet of the present invention does not need to be provided with a re-peelable pressure-sensitive adhesive layer on both sides facing the temporary adhesion planned surface, and since one side may be an overprint layer, a conventional re-peelable pressure-sensitive adhesive layer is provided on both sides. further possible cheaper than those provided, there is an effect that the pressure-sensitive adhesive sheet requires high designability by full-color printing in the direct mail or the like can be realized at a low cost.
[0028]
Further, as shown in FIG. 5A, the Z-folded sheet has the re-peelable pressure-sensitive adhesive layer 2 on the surface of the central piece 14 and the right piece 15, and the strong adhesive layer 7 for permanent adhesion on the back surface of the left piece 13 and the central piece 14. Depending on the thickness of these layers, the thickness of the central piece is larger than that of the left and right pieces when the continuous sheet is stacked in a zigzag fold as shown in FIG. Therefore, the central piece tends to be a mountain as shown in FIG. 6 (b). However, in the pressure-sensitive adhesive sheet of the present invention, since an overprint layer thinner than the releasable adhesive layer 2 can be provided on the central piece 14 as shown in FIG. 5B, each piece (left piece, central piece) The right piece) has a substantially uniform thickness, so that the stable shape shown in FIG. 6A can be maintained without stocking as shown in FIG. This prevents troubles in paper feeding and paper ejection in a non-impact printer.
[Brief description of the drawings]
FIG. 1 is a surface view of a folded postcard paper as an embodiment of the pressure-sensitive adhesive sheet of the present invention.
2 is a cross-sectional view taken along the line AA of the postcard paper of FIG. 1. FIG.
3 is a back view of the postcard paper in FIG. 1. FIG.
4 is a cross-sectional view of a folded postcard obtained from the postcard paper of FIG. 1. FIG.
FIG. 5 is a cross-sectional view of a Z-fold pressure-sensitive adhesive sheet. (A) is conventional and (b) is the present invention.
FIG. 6 is a diagram illustrating a stock shape in which pressure-sensitive adhesive sheets are stacked in a zigzag manner. (A) is a flat shape by the sheet | seat of this invention, (b) is the mountain shape by the conventional sheet | seat.
[Explanation of symbols]
1 substrate 2 removable pressure-sensitive layer 3a, 3b visible information 4 overprint layer 5 fold lines 6 UV-curable resin layer 7 Strong adhesive layer 10 pressure-sensitive adhesive sheet 11 first sheet 12 second sheet 13 left piece 14 central piece 15 Right piece 20 Postcard S Peeling surface

Claims (3)

Have a temporary adhesive scheduled surface facing by folio, on one surface of the temporary bonding scheduled surfaces facing during temporary adhesion only after prior adhesion and peeling did not adhere in a normal state, to adhere at least the pressure In the pressure-sensitive adhesive sheet on which the re- peelable pressure-sensitive adhesive layer is applied and formed , the re-peelable pressure-sensitive adhesive layer is a re-peelable pressure-sensitive adhesive layer having transparency including a filler composed of resin particles in the pressure-sensitive adhesive base material. A transparent overprint layer made of an ultraviolet curable resin is formed on the other surface of the planned adhesion surface, and when peeled, it was peeled off between the re-peelable pressure-sensitive adhesive layer and the overprint layer. Characteristic pressure-sensitive adhesive sheet. The adhesive base resin is a styrene - butadiene rubber latex, an acrylonitrile - butadiene rubber latex and pressure-sensitive adhesive sheet according to claim 1 Symbol mounting, characterized in adhesive main agent der Rukoto selected from the group consisting of acrylic resin latex. The pressure-sensitive adhesive sheet according to claim 1 or 2 , wherein the filler contains one or both of polystyrene particles and polymethyl methacrylate particles.

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