JP4093728B2 - Adhesive sheet laminate and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an aqueous coating agent-coated sheet and an adhesive sheet laminate. More specifically, the present invention provides an aqueous coating agent coated sheet in which curling and wrinkle phenomenon after drying is suppressed by performing a drying treatment of the aqueous coating agent applied to the substrate by high-frequency dielectric heating. The present invention relates to a method for producing well, and a pressure-sensitive adhesive sheet laminate having a good appearance without undulations, which is formed by laminating a plurality of pressure-sensitive adhesive sheets obtained by the above method.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a water-absorbing substrate such as paper or cloth is often partially coated with a specific pattern, partly with a water-based coating agent such as a water-based adhesive, water-based paint, or water-based printing ink. However, when a water-based base material is partially coated on a water-absorbing substrate and dried with hot air, which is usually performed, due to the difference in water content between the coated part and the non-coated part, This leads to an unfavorable situation in which the phenomenon of curl or wave occurs.
In order to suppress the occurrence of such curling and wavy phenomenon, there are currently many methods for adjusting the moisture after the drying process, but this method sufficiently suppresses the occurrence of the curling and wavy phenomenon. I can't.
On the other hand, a label is affixed on the surface of a home delivery cargo or a product package to indicate the type and handling of the cargo or product. Labels such as home delivery labels, product labeling labels, precautionary labels, etc., which have been superimposed on a backing sheet made of paper-like or tape-like release paper so far, are peeled off from the paper-like backing paper, or tape-like labels. The mount was cut at a certain position and then peeled off.
However, such a display label is unfavorable for the environment because the release paper remains as dust after using it, and the amount of waste increases according to the amount of use, and when the tape-like mount is cut. It had drawbacks such as the risk of injury.
[0003]
Therefore, as an improvement of such drawbacks, an adhesive layer is provided by applying an adhesive, leaving a non-coated portion in contact with the edge of the substrate on one side of the substrate, and a release layer is provided on the opposite side. A pressure-sensitive adhesive sheet laminate in which a plurality of pressure-sensitive adhesive sheets are laminated with the pressure-sensitive adhesive layer and the release layer facing each other has been proposed (Registered Utility Model Publication No. 3003840). Such a pressure-sensitive adhesive sheet laminate is a simple operation that only peels and sticks the pressure-sensitive adhesive sheets one by one, so that it is easy to use and safe, and does not generate waste such as release paper. Have.
In the method for producing a pressure-sensitive adhesive sheet used in such a pressure-sensitive adhesive sheet laminate by applying a water-based pressure-sensitive adhesive to a part of one side of a water-absorbent substrate and subjecting it to hot air drying treatment, it is obtained as described above. Curling and wavy phenomena occur on the adhesive sheet. Therefore, in the case of laminating a plurality of these layers, the resulting adhesive sheet laminate has a problem that the coated part is lifted, a wave-shaped wave is formed, and the appearance is unavoidably impaired. Occurs.
[0004]
By the way, when applying a water-system coating agent to a water-absorbing base material and drying it, a hot air dryer is usually used. However, when the undried aqueous coating material coating sheet is dried with a hot air dryer, the partial coating of the aqueous coating material may cause problems such as curling and undulation, and the coating layer For the formation, in general, a transfer method in which release paper becomes waste instead of direct coating is used.
On the other hand, a high frequency dielectric heating method is known as a heating method. This high frequency dielectric heating method is a method of heating by high frequency using the dielectric loss of the material to be heated, and does not require the heat conduction of the material to be heated. Specifically, it is used, for example, for drying wood, bonding or molding plastics.
[0005]
[Problems to be solved by the invention]
Under such circumstances, the present invention provides a method for efficiently producing a water-based coating agent-coated sheet in which curling and wavy phenomena after drying are suppressed, and a plurality of pressure-sensitive adhesive sheets obtained by the above method are overlapped. It is an object of the present invention to provide a pressure-sensitive adhesive sheet laminate having a good appearance with no wave.
[0006]
[Means for Solving the Problems]
The present inventors have made intensive studies in order to achieve the object, an emulsion-type aqueous adhesive and high-frequency dielectric heating treatment after coating a portion of the water-absorbent substrate surface, further to hot air drying It has been found that a pressure-sensitive adhesive sheet laminate comprising a plurality of water-based pressure-sensitive adhesive coated sheets can be adapted to its purpose. The present invention has been completed based on such findings.
That is, the present invention includes (1) a plurality of water-based pressure-sensitive adhesive-coated sheets obtained by applying an emulsion-type water-based pressure-sensitive adhesive to a part of the surface of a water-absorbing substrate, followed by high-frequency dielectric heat treatment , and further hot-air drying. Combined pressure-sensitive adhesive sheet laminate , ( 2 ) When the difference between the water content after coating the emulsion-type water-based pressure-sensitive adhesive and the water content after high-frequency dielectric heating treatment and hot-air drying treatment is 100%, adhesive sheet laminate according to the high-frequency dielectric heating treatment on SL was 60-70% of dry rate by (1), (3) water-absorbent substrate is paper or cloth der Ru (1) above or ( adhesive sheet laminate 2), (4) above Symbol you high-frequency dielectric heating by installing a high-frequency electrode on the side of the emulsion-type water-based adhesive coating to the surface opposite to the surface of the water absorbing substrate (1) -( 3 ) Adhesive sheet laminated body in any one of ( 3 ), and (5) Water absorption A laminate of pressure-sensitive adhesive sheets, wherein a plurality of water-based pressure-sensitive adhesive coated sheets obtained by applying an emulsion-type water-based pressure-sensitive adhesive to a part of the surface of a conductive substrate, followed by high-frequency dielectric heat treatment and further drying with hot air are superposed. Manufacturing method ,
Is to provide.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the method for producing an aqueous coating agent-coated sheet of the present invention, a water-absorbing substrate is used as the substrate. Preferred examples of the water-absorbing substrate include paper such as high-quality paper, kraft paper, glassine paper, and coated paper, and fabrics such as woven fabrics and nonwoven fabrics of natural fibers and synthetic fibers.
The thickness of the water-absorbing substrate is not particularly limited and may be appropriately selected depending on various situations, but is usually in the range of 10 to 300 μm, preferably 50 to 150 μm.
In the method of the present invention, a water-based coating agent is partially applied to the surface of the water-absorbing substrate.
The aqueous coating agent is not particularly limited, and may be selected from, for example, an aqueous adhesive, an aqueous paint, an aqueous printing ink, an aqueous heat-sealable coating agent, an aqueous barrier coating agent, etc. It can be selected appropriately.
Here, the water-based adhesive can be roughly classified into a water-soluble type and an aqueous emulsion type, and examples of the water-soluble type adhesive include polyvinyl alcohol, polyvinyl methyl ether, polyvinyl pyrrolidone, polyacrylamide, and polycarboxylic acid. The thing which mix | blended tackifier etc. with the polymer, dextrin, etc. can be mentioned. On the other hand, examples of the aqueous emulsion type pressure-sensitive adhesive include acrylic emulsion, natural rubber latex, and styrene-butadiene copolymer latex.
[0008]
Examples of water-based paints include carboxylic acid groups of polycarboxylic acid resins such as maleated oil-modified resins, maleated fatty acid-modified polyesters, special phenol resin-modified resins, acrylic resins containing acrylic acid as a monomer component, and trimellitic acid-modified alkyd resins. Water-soluble paints containing those derived from alkali metal salts, ammonium salts, amine salts, and the like, and powdery water-based paints, inorganic paints, silicate paints, and the like.
Examples of water-based printing inks include water-based paint-based or water-based pigment-based inks used for inkjet printers, etc., water-based heat-sealable coating agents such as rubber latex-based coating agents, and water-based barrier coating agents. Examples thereof include a vinylidene chloride copolymer latex coating agent.
Among these water-based coating agents, the water-based pressure-sensitive adhesive is applied with a thickness of about 10 to 200 μm in a state before drying, and since there is a relatively large difference in water content between the coated part and the non-coated part, It is particularly advantageous to apply the method of the invention when using an adhesive.
There are no particular restrictions on the coating method of this aqueous coating agent, and there are no known methods such as spray coating, bar coating, knife coating, roll coating, blade coating, and die coating. It can be appropriately selected and used according to the above.
The thickness of the coating layer of the aqueous coating agent (dry state) is appropriately selected according to the intended use of the product to be obtained, but is usually in the range of 5 to 100 μm, preferably 10 to 50 μm.
[0009]
In the method of the present invention, after applying the aqueous coating agent to a part of the substrate surface in this way, the target aqueous coating agent coated sheet is produced by drying treatment as shown below. .
In the drying treatment in the present invention, a method of applying a high-frequency dielectric heat treatment after applying an aqueous coating agent is used.
For the high-frequency dielectric heat treatment, a high-frequency dielectric heating apparatus having a frequency of about 10 to 50 MHz can be used, which is a frequency defined by ISM (INDUSTRIAL, SCIENTIFIC and MEDICAL) standards, 13.56 MHz ± 6.78 KHz, It is preferable to use 27.12 MHz ± 162.72 KHz or 40.68 MHz ± 20.34 KHz.
[0010]
As a high-frequency dielectric heating device, a high-frequency electrode can be used either on the upper side of the water-absorbing substrate (coating side) or on the lower side (opposite side of the coating). It is more preferable to use the one installed on the side) for the reason described below.
That is, the applied aqueous coating solution tends to penetrate into the water-absorbing substrate due to wettability, capillary action, and the like. When a high-frequency electrode is installed below the substrate that has penetrated this aqueous coating solution, the high-frequency power is not only used for heating and drying the coating film, but also for heating and drying the coating solution that has penetrated the substrate. Although it works, it is heated in a short time because the amount of coating solution (weight per unit area) during penetration is small. In the coating liquid that has been heated in this way, part of the water evaporates and diffuses into the base material, increasing the concentration and viscosity of the remaining liquid, which also penetrates deeper into the base material. Also, new penetration from the coating film is prevented. Accordingly, the penetration of the coating liquid into the water-absorbing substrate is limited to the vicinity of the interface and is rapidly dried, so that the expansion deformation of the substrate and the ripple phenomenon after drying can be more reliably suppressed.
On the other hand, when the high-frequency electrode is installed above the water-absorbing substrate, the high-frequency power is mainly used for heating and drying of the coating film due to the shielding action of the coating film. The overheating / drying effect of the permeating coating solution is weakened, and the effect of preventing the penetration is reduced.
The temperature of the aqueous coating agent immediately after passing through the high-frequency dielectric heating device is preferably 50 to 90 ° C, more preferably 60 to 80 ° C.
[0011]
Thus, it is preferable that the coating sheet subjected to the high frequency dielectric heat treatment is further subjected to a hot air drying treatment, whereby the surface state of the coating film can be improved. Thus, in the case where the high frequency dielectric heat treatment and the hot air drying treatment are used in combination, the difference between the water amount after coating the aqueous coating agent and the water amount after the high frequency dielectric heat treatment and hot air drying treatment is 100%. When the drying rate is set, the drying rate by high-frequency dielectric heat treatment is preferably 60 to 70%. If the drying rate is less than 60%, the effect of the high-frequency dielectric heat treatment may not be sufficiently exerted. On the other hand, if it exceeds 70%, moisture in the coating film will boil in this heating treatment, resulting in poor appearance of the dried coating film. Cause. The temperature of the hot air drying treatment is preferably 60 to 90 ° C, more preferably 70 to 80 ° C. There is no restriction | limiting in particular as a hot air dryer used for this hot air drying process, The hot air dryer conventionally conventionally used for the drying process of the aqueous | water-based coating agent coating sheet can be used.
[0012]
The coating and drying speed is usually in the range of 3 to 300 m / min. Even if the aqueous coating agent is partially applied, curling and undulation are less likely to occur after drying. Further, in the past, a coating film provided by a transfer method can directly apply a water-based coating agent to a water-absorbing substrate. Such a method of the present invention is advantageously applied particularly to thick coating or partial coating of an aqueous coating agent.
[0013]
FIG. 1 is a schematic view of an example of an apparatus that can be used in the method for producing an aqueous coating material coated sheet of the present invention. As shown in this figure, for example, an aqueous system comprising a roll knife 2 and a coating roll 3 is used. It has a coating agent coating mechanism, a high frequency dielectric heating device 6 and a hot air dryer 7.
[0014]
The water-absorbing substrate 1 delivered from a delivery roll (not shown) is first supplied to the aqueous coating agent coating mechanism, and the aqueous coating agent 4 has a predetermined thickness by the roll knife 2 and the coating roll 3. So that it is coated. The undried coating sheet 5 is sent to the high frequency dielectric heating device 6 and dried by about 60 to 70%, and then sent to the hot air dryer 7 to be almost completely dried. The aqueous coating material coated sheet 8 thus produced is wound up by a winding roll (not shown) or supplied to the laminating process. In addition, you may adjust a water | moisture content after a drying process.
[0015]
Next, the pressure-sensitive adhesive sheet laminate of the present invention will be described.
As the aqueous coating agent, an aqueous adhesive having a thickness of usually 5 to 50 μm, preferably about 10 to 30 μm, is formed on at least a part of one side of the water-absorbing substrate by the above-described production method of the present invention. An adhesive sheet having a layer is prepared.
The pressure-sensitive adhesive sheet having the water-based pressure-sensitive adhesive layer on one surface thus obtained is cut into a predetermined size, and a plurality of the pressure-sensitive adhesive sheets are stacked to obtain the pressure-sensitive adhesive sheet laminate of the present invention. In addition, a peeling layer may be provided in the surface on the opposite side to the surface which has a water-based adhesive layer of a water absorbing base material, and a water-based adhesive layer and a peeling layer may be made to face, and an adhesive sheet laminated body may be created.
This release layer does not need to be provided on the entire surface of the water-absorbent substrate, and is at least part of the surface of the substrate opposite to the water-based pressure-sensitive adhesive layer, usually water-based pressure-sensitive adhesive of other pressure-sensitive adhesive sheets laminated on the pressure-sensitive adhesive sheet. What is necessary is just to provide in the area | region corresponding to an agent layer. By providing the release layer partially, it is possible to stamp or write on a portion where the release layer does not exist.
The pressure-sensitive adhesive sheet laminate of the present invention has a good appearance with no wave.
[0016]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
Example 1
A high-quality paper having a thickness of 70 μm and a width of 300 mm was used as the water-absorbing substrate, and water-based adhesive coating and high-frequency dielectric heating were continuously performed. The following test apparatus was used as the high frequency dielectric heating apparatus.
<High-frequency dielectric heating device>
・ Maximum output: 2.2kW
・ Electrode: Brass, 4mm in diameter
・ Electrode arrangement: 19 lines perpendicular to the flow direction at 15 mm intervals ・ Frequency: 40.68 MHz ± 20.3 kHz
・ Device dimensions: Length 320mm, width 540mm
First, the thickness of the coating layer (pressure-sensitive adhesive layer) after drying the water-based pressure-sensitive adhesive (acrylic emulsion type, solid content concentration 59.2% by weight) so that the width is 100 mm at the center of one side of the substrate. After coating with a roll knife coater so as to be 40 μm, immediately after passing through the device by a high-frequency dielectric heating device in which a high-frequency electrode is installed below the substrate (the side opposite to the surface coated with the water-based adhesive) Heat treatment at a temperature of 77.2 ° C. The coating / drying rate was 5 m / min, and the residual water content of the pressure-sensitive adhesive layer immediately after passing through the high-frequency dielectric heating device was 0.9 g / m ² .
In this coated sheet, no curling or wavy phenomenon occurred.
[0017]
Example 2
In Example 1, except that the temperature immediately after passing through the high-frequency dielectric heating apparatus was 85.8 ° C., and subsequently dried at 70 ° C. using a hot air dryer at a coating / drying rate of 7 m / min. The same operation was performed.
The moisture content contained in the adhesive layer of the undried coated sheet is 27.6 g / m ² , and the moisture content of the adhesive layer immediately after passing through the high-frequency dielectric heating device is 8.2 g / m ² , so The drying rate by the treatment was 69.5%. Moreover, the moisture content of the adhesive layer after drying with a hot air dryer was 0.7 g / m ² .
In the obtained coated sheet, no curling or wavy phenomenon occurred, and the surface state of the coating film (adhesive) was good.
Example 3
The water-based pressure-sensitive adhesive coated sheets obtained in Examples 1 and 2 were cut into a size of 100 mm × 100 mm so as to have a pressure-sensitive adhesive layer having a width of 50 mm on one side, and 100 sheets thereof were stacked to form a pressure-sensitive adhesive sheet laminate. .
There was no wave in this pressure-sensitive adhesive sheet laminate.
[0018]
Comparative Example 1
Using the same base material and aqueous adhesive as in Example 1, aqueous adhesive coating and hot air drying treatment were continuously performed.
First, in the same manner as in Example 1, a water-based pressure-sensitive adhesive was applied to a substrate, and then dried at a temperature of 90 ° C. with a hot air dryer to obtain a coated sheet. The coating / drying speed was 7 m / min. The residual moisture content of the pressure-sensitive adhesive layer after drying was 0.9 g / m ² . This coated sheet was curled and wavy.
[0019]
【The invention's effect】
According to the production method of the present invention, the drying treatment of the undried coating sheet is performed by a combination of high-frequency dielectric heating and hot air drying, so that the curling and wave phenomenon after drying are suppressed. Can be manufactured efficiently.
In addition, by stacking a plurality of the pressure-sensitive adhesive sheets obtained by the method of the present invention, it is possible to obtain a pressure-sensitive adhesive sheet laminate having a good appearance with no wave.
[0020]
[Brief description of the drawings]
FIG. 1 is a schematic view of an example of an apparatus that can be used in the method for producing an aqueous coating agent-coated sheet of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Water-absorbing base material 2 Roll knife 3 Coating roll 4 Aqueous coating agent 5 Undried coating sheet 6 High frequency dielectric heating device 7 Hot air dryer 8 Aqueous coating agent coating sheet

Claims (5)

A pressure-sensitive adhesive sheet laminate in which a plurality of water-based pressure-sensitive adhesive coated sheets obtained by applying an emulsion-type water-based pressure-sensitive adhesive to a part of the surface of a water-absorbing substrate and then subjecting it to high-frequency dielectric heat treatment and further hot-air drying treatment . When the difference between the water content after coating the emulsion-type water-based pressure-sensitive adhesive and the water content after the high-frequency dielectric heat treatment and hot-air drying treatment is 100%, the drying rate by the high-frequency dielectric heat treatment is 60 to 70. % and then the adhesive sheet laminate according to claim 1. The pressure-sensitive adhesive sheet laminate according to claim 1 or 2 , wherein the water-absorbing substrate is paper or cloth . The pressure-sensitive adhesive sheet laminate according to any one of claims 1 to 3 , wherein the high-frequency dielectric heat treatment is performed by installing a high-frequency electrode on the side opposite to the surface of the water-absorbing substrate coated with the emulsion-type water-based pressure-sensitive adhesive . Adhesive sheet lamination characterized by superposing a plurality of aqueous adhesive coated sheets obtained by applying an emulsion-type aqueous adhesive on a part of the surface of the water-absorbent substrate, followed by high-frequency dielectric heat treatment, and further hot-air drying treatment Body manufacturing method.

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