JP6802682B2 - Manufacturing method of removable sheet - Google Patents

Description

The present invention relates to a method for producing a removable sheet provided with a pressure sensitive adhesive layer having removability.

The removable sheet, which is provided with a pressure-sensitive adhesive layer having removability on the surface of the base sheet, and the base sheets are pressure-bonded to each other via the adhesive layer to be removably bonded, has various uses. It is used in Japan and is widely used in society. A pressure-sensitive crimping postcard is exemplified as a typical releasable sheet, and is used in a postcard system having confidentiality.

In a postcard system with confidentiality, for example, a postcard containing various information such as personal requirements, print information, print information, etc. can be folded, cut, or superposed on top of each other. It can be reattached, concealed various information, and then mailed. The postcard allows the recipient to re-peel the overlapping surfaces and read the concealment information.

In the removable sheet, the pressure-sensitive adhesive layer is formed by applying the pressure-sensitive adhesive composition to the target overlapping surface of the base sheet and drying the sheet during its production. Various information is inkjet-printed on the pressure-sensitive adhesive layer (see, for example, Patent Document 1).
The removable sheet can be produced by releasably adhering the overlapped surfaces to each other via a pressure-sensitive adhesive layer.

Japanese Patent No. 3437744

In the method for producing a removable sheet, for example, when a binder such as a water-soluble polymer is blended in the pressure-sensitive adhesive layer, the adhesive strength of the pressure-sensitive adhesive layer is enhanced in a high temperature and high humidity environment. , The bonded overlapping surface may be difficult to peel off again.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a removable sheet capable of suppressing an increase in the adhesive force of a pressure-sensitive adhesive layer.

One aspect of the present invention is a removable sheet provided with a pressure-sensitive adhesive layer on the surface of the base material sheet, and the overlapped surfaces of the base material sheets can be removably adhered to each other via the pressure-sensitive adhesive layer. It is a manufacturing method of
A step of applying a pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer to the surface of the base material sheet to form the pressure-sensitive adhesive layer, and a step of forming the pressure-sensitive adhesive layer.
A step of laminating the base material sheet on which the pressure-sensitive adhesive layer is formed so that the superposed surfaces face each other.
It has a step of sandwiching the overlapped base material sheets with a pair of pressurizing bodies and applying pressure to bond the overlapped surfaces to each other so as to be removable.
The pressure-sensitive adhesive composition contains an adhesive base containing a natural rubber-based material, an adhesive force adjusting agent containing silica, and a water-soluble polymer.
In the step of forming the pressure-sensitive adhesive layer, the coating amount of the pressure-sensitive adhesive composition was set to 1 to 8 g / m ² .
Manufacture of a removable sheet in which the distance between the pressure surfaces of the pair of pressurizing bodies is 66 to 90% of the thickness of the overlapped base sheet in the step of adhering the overlapped base sheets. A method, a method for producing a removable sheet is provided.

According to one aspect of the present invention, it is possible to suppress an increase in the adhesive force of the pressure-sensitive adhesive layer.

It is a block diagram which shows typically the manufacturing apparatus which can carry out the manufacturing method of the removable sheet which concerns on one Embodiment of this invention. It is a block diagram which shows the part of the manufacturing apparatus shown in FIG. 1 enlarged. It is sectional drawing which shows an example of the removable sheet schematically. It is a surface development view of the tri-fold postcard obtained by the manufacturing method which concerns on one Embodiment of this invention. It is a back side development view of the tri-fold postcard shown in the previous figure. It is a figure explaining the superimposition process. It is sectional drawing which shows typically the removable sheet which concerns on other embodiment of this invention. It is a figure which shows the time-dependent change of the adhesive force in an Example and a comparative example. It is a figure which shows the transfer stain in an Example and a comparative example.

<Manufacturing method of removable sheet>
In the method for producing a removable sheet according to an embodiment of the present invention, a pressure-sensitive adhesive layer is provided on the surface of the base sheet, and the overlapping surfaces of the base sheet are reassembled via the pressure-sensitive adhesive layer. A method for producing a removable sheet that can be peelably adhered, wherein a pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer is applied to the surface of the base material sheet to apply the pressure-sensitive adhesive. A step of forming a layer, a step of superimposing the base sheet on which the pressure-sensitive adhesive layer is formed so that the overlapped surfaces face each other, and a pair of pressurization of the overlapped base sheet. The pressure-sensitive adhesive composition includes an adhesive base containing a natural rubber-based material and silica, which comprises a step of sandwiching and pressurizing by a body to reattach the overlapped surfaces to each other so as to be removable. In the step of forming the pressure-sensitive adhesive layer containing the adhesive force adjusting agent and the water-soluble polymer, the coating amount of the pressure-sensitive adhesive composition is set to 1 to 8 g / m ² , and the stacking is performed. In the step of adhering the combined base sheet, the distance between the pressure surfaces of the pair of pressurizing bodies is set to 66 to 90% of the thickness of the overlapped base sheet.
Hereinafter, the removable sheet obtained by the embodiment of the present invention will be described.

<Removable sheet>
The removable sheet obtained by the production method of the embodiment is a removable sheet capable of releasably adhering the overlapped surfaces to each other, and is provided on at least one surface of the base sheet and the base sheet. The pressure-sensitive adhesive composition comprises a pressure-sensitive adhesive layer, an adhesive base containing a natural rubber-based material, an adhesive force adjusting agent containing silica, and a water-soluble polymer. The coating amount of the pressure-sensitive adhesive composition is 1 to 8 g / m ² .

The removable sheet may be in a state in which the overlapping surfaces of the base material sheets are bonded to each other by the pressure-sensitive adhesive layer, or in a non-bonded state before being bonded by the pressure-sensitive adhesive layer. There may be.

The pressure-sensitive adhesive layer can be formed, for example, by applying a pressure-sensitive adhesive composition containing components constituting the pressure-sensitive adhesive layer to the surface of the base material sheet and drying the pressure-sensitive adhesive layer.

FIG. 3 is a cross-sectional view schematically showing a removable sheet obtained by the production method according to the embodiment of the present invention. Note that FIG. 3 may be shown by enlarging a main part for convenience, for example, and the dimensional ratios and the like of each component are not always the same as the actual ones. This is the same in other figures.
The removable sheet 1 shown here includes a base sheet 11 and pressure-sensitive adhesive layers 12 and 12 provided on the surfaces 11a and 11b, which are one and the other surfaces of the base sheet 11.
The removable sheet 1 is capable of removably adhering the overlapping surfaces (surfaces 11a and 11b) of the base sheet 11 to each other via the pressure-sensitive adhesive layer 12.
The surface 12a of the pressure-sensitive adhesive layer 12 serves as an adhesive surface when the overlapping surfaces of the base sheet 11 are removably bonded to each other.

A printing layer 14 is formed on the surface 12a of the pressure-sensitive adhesive layer 12. The removable sheet 1 can be used as a so-called pre-glue type removable sheet in which the printing layer 14 is formed on the surface 12a side of the pressure-sensitive adhesive layer 12.

In the removable sheet 1, the surfaces 12a of the pressure-sensitive adhesive layer 12 are adhered to each other, and the overlapping surface (surface 11a or surface 11b) of the base material sheet 11 is re-peeled with the surface 12a as the peeling surface.

The removable sheet is not limited to the one shown here, and a part of the structure shown here has been changed or deleted, or the one described above, within a range that does not impair the effects of the present invention. Other configurations may be added to the above.
For example, as in the removable sheet 1A shown in FIG. 7, the pressure-sensitive adhesive layer 12 may be provided only on the surface 11a of the base sheet 11.

The shape of the print layer 14 can be arbitrarily selected according to the purpose. The print layer 14 may have a single-layer structure or a multi-layer structure having two or more layers. The shapes of the plurality of layers may be the same or different from each other.
In the removable sheet, one releasable sheet may be folded and the overlapping surfaces of the base sheets may be adhered to each other, or separate removable sheets may be laminated with each other. At the mating surfaces, they may be adhered by a pressure sensitive adhesive layer.

In the removable sheet, the overlapping surface of the base sheet is not the same overlapping surface of the base sheet, but is adhered (bonded) to the surface of the release paper whose surface is peeled. May be good. When a release paper is used, it is preferable that the release-treated surface is adhered to the overlapping surface of the base sheet of the removable sheet. Even when such a release paper is used, the removable sheet has removability.

Next, each layer constituting the removable sheet obtained by the production method according to the first embodiment of the present invention will be described in detail.

<Base sheet>
The base material sheet is made of a material including, for example, paper. Examples of the base sheet include high-quality paper, base paper, art paper, coated paper, cast-coated paper, resin-coated paper, synthetic paper, and the like, and high-quality paper is particularly preferable. Since it is a high-quality paper, when a water-based emulsion type adhesive is applied to form a pressure-sensitive adhesive layer, the formation of the adhesive is good and the ink absorbency at the time of performing inkjet printing is good. is there.
The material of the base sheet may be only one type, may be two or more types, and when there are two or more types, the combination and ratio thereof can be arbitrarily selected according to the purpose. The base sheet is preferably made of paper as the material of the coated surface of the pressure-sensitive adhesive composition.

For the base sheet (wood free paper), for example, the air permeability measured in accordance with JIS P8117 is preferably 300 seconds or less, and more preferably 200 seconds or less. When the air permeability is in the above range, the base sheet is provided with sufficient ink absorbency, and the ink acceptability is enhanced.

The thickness of the base sheet is not particularly limited, but is usually preferably 50 to 300 μm, and more preferably 80 to 200 μm.

The base material sheet may be composed of a single layer or may be composed of a plurality of layers of two or more layers (a layer in which a plurality of layers are laminated). When the base sheet is composed of a plurality of layers, the plurality of layers may be the same or different from each other. That is, all layers may be the same, all layers may be different, or only some layers may be different. When the plurality of layers are different from each other, the combination of the plurality of layers is not particularly limited. Here, when a plurality of layers are different from each other, it means that at least one of the material and the thickness of each layer is different from each other.
When the base sheet is composed of a plurality of layers, the total thickness of each layer may be set to be the above-mentioned preferable thickness of the base sheet.

<Pressure-sensitive adhesive layer>
The pressure-sensitive adhesive layer can be formed by applying a pressure-sensitive adhesive composition containing components constituting the pressure-sensitive adhesive layer to the surface of the base material sheet and drying the pressure-sensitive adhesive layer.

[Pressure-sensitive adhesive composition]
The pressure-sensitive adhesive composition is not particularly limited as long as it is a pseudo-adhesive, and known ones can be used.
The pressure-sensitive adhesive composition contains an adhesive base, an adhesive force modifier, and a water-soluble polymer.
The adhesive force adjuster inhibits the development of the adhesive force by the adhesive base, adjusts the adhesive force of the pressure-sensitive adhesive layer, suppresses the advancement of the adhesive force, and improves the blocking resistance. It is an ingredient. The adhesive base and the adhesive force adjusting agent are components for exhibiting pressure-sensitive adhesiveness.

(Adhesive base)
The adhesive base contains a natural rubber-based material. Examples of the natural rubber-based material include natural rubber, modified rubber obtained by modifying natural rubber, and the like.
The adhesive base is an organic solvent type using an organic solvent, a water type using water as a medium, a radiation curing type that cures by irradiation with radiation such as ultraviolet rays, and a heat curing type that cures by heating. And so on.
In the present specification, the term "adhesive base" means a solid material such as the natural rubber, and does not include a liquid medium such as the organic solvent or water, unless otherwise specified.
The adhesive base is preferably water-based, and more preferably a natural rubber-based aqueous emulsion type. Compositions such as emulsions using an aqueous adhesive base have low volatility, so that the amount of coating can be easily adjusted, and the suitability for coating on a base sheet is higher. Further, such a composition is harmless to the human body because the medium is water, is not flammable, and does not require special equipment such as explosion-proof equipment in the coating process and the drying process.

Examples of the natural rubber-based aqueous emulsion type adhesive base (natural rubber-based material) include those known as bases for natural rubber-based pressure-sensitive adhesives. For example, latex containing natural rubber as a main component (natural rubber latex). ); Modified latex containing the modified rubber modified from the natural rubber as a main component, such as acidic latex, depolymerized latex, vulture latex, grafted natural rubber latex; styrene relative to the natural rubber latex or modified latex. Examples thereof include a mixture containing an appropriate amount of one or more selected from the group consisting of rich SBR latex, polystyrene emulsion and styrene / acrylic copolymer emulsion. The monomer or oligomer used for grafting natural rubber can be arbitrarily selected depending on the purpose as long as it has a polymerizable group. For example, in the case of a monomer, an alkyl ester of (meth) acrylic acid, styrene, etc. Those having a polymerizable unsaturated double bond can be mentioned. Here, the alkyl ester is preferably a methyl ester or an ethyl ester.

A preferable natural rubber-based aqueous emulsion type adhesive base is a natural rubber (meth) acrylic acid alkyl ester such as methyl methacrylate, particularly from the viewpoint of blocking resistance, heat resistance, abrasion resistance and the like. Those modified with a monomer are preferable. For example, mainly modified latex containing modified rubber as a main component obtained by graft-polymerizing methyl methacrylate (MMA) on natural rubber, and modified rubber obtained by graft-polymerizing styrene and methyl methacrylate on natural rubber. Examples thereof include modified latex as an ingredient.
Preferable modified rubber obtained by graft-polymerizing methyl methacrylate on natural rubber includes, for example, graft-polymerizing 10 to 40 parts by mass of methyl methacrylate with respect to 100 parts by mass of natural rubber. ..

A preferable modified rubber obtained by graft-polymerizing styrene and methyl methacrylate on natural rubber is, for example, polymerized by a total of 30 to 70 parts by mass of styrene and methyl methacrylate with respect to 100 parts by mass of natural rubber. The ones that were made to be mentioned.
As the adhesive base (natural rubber-based material), natural rubber-based latex in which natural rubber and (meth) acrylic acid alkyl ester such as methyl methacrylate are mixed, and natural rubber and protective colloid-based acrylic copolymer emulsion are used. A mixed natural rubber latex can also be used.

Specific examples of the (meth) acrylic acid alkyl ester monomer include methyl (meth) acrylic rate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, and i-butyl (meth). Examples include acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, isononyl (meth) acrylate, and dodecyl (meth) acrylate. And one or more selected from these groups can be used.

The adhesive base may contain an acrylic-modified rubber latex, a mixture of the rubber latex and a protective colloidal acrylic copolymer emulsion, and the like.

The adhesive base may contain a natural rubber-based material as an essential component and may contain a synthetic diene-based rubber material as an optional component. The diene rubber material is a rubber material containing a double bond in the main chain, and is styrene butadiene latex (SBR), butadiene rubber (BR), nitrile rubber (NBR), isoprene rubber (IR), chloroprene rubber (CR). In particular, styrene-butadiene latex (SBR) is preferable.

The ratio (mass basis) of the blending amount of the natural rubber-based material and the diene-based rubber material is preferably 11.5: 0.5 to 9.5: 2.5, and more preferably 11: 1 to 10: 2.
When the ratio of the blending amount of the natural rubber-based material is equal to or higher than the lower limit of the above range, sufficient adhesive force can be obtained even if the pressure when the sheet is pressed and adhered is low, so that the adhesive force becomes too large. The removability of the removable sheet can be improved. Further, since the adhesive force required for the pressure-sensitive adhesive layer can be secured, it is possible to prevent the overlapped surfaces from peeling off at the stage of, for example, transporting or sorting the removable sheet.
When the ratio of the blending amount of the diene-based rubber material is at least the lower limit of the above range, the strength of the pressure-sensitive adhesive layer can be increased and the wear resistance can be improved. Therefore, it is possible to prevent a part of the pressure-sensitive adhesive layer from adhering to the roll or the like of the sealing device.

In the pressure-sensitive adhesive composition, the ratio of the blending amount of the natural rubber-based material in the adhesive base is preferably, for example, 79% by mass or more, and more preferably 83% by mass or more. The ratio of the blending amount of the natural rubber-based material in the adhesive base is preferably 96% by mass or less, more preferably 92% by mass or less.
The ratio of the blending amount of the natural rubber-based material in the adhesive base may be 100% by mass.

As the adhesive base, one type may be used alone, two or more types may be used in combination, and when two or more types are used in combination, the combination and ratio thereof should be appropriately selected according to the purpose. Just do it. However, when two or more kinds are used in combination, it is preferable to use adhesive bases of the same type as each other.

In the pressure-sensitive adhesive composition, the ratio of the compounding amount of the adhesive base (solid content) to the total amount of the compounding components other than the liquid medium (total amount of the solid compounding components) is 20 to 97% by mass. It is preferably 20 to 50% by mass, and more preferably 20 to 50% by mass.

When preparing the pressure-sensitive adhesive composition, there are components such as the above-mentioned adhesive base that are dissolved or dispersed in a liquid medium such as water or an organic solvent, which are described in the present specification. Unless otherwise specified, the blending amount of these components in the above means the blending amount as a solid content even if there is no notation such as "(solid content)" as described above.

(Adhesive strength adjuster)
Examples of the adhesive force adjusting agent include fillers, waxes, and the like, and examples thereof include those having a low affinity with the adhesive base. All of these adjust the adhesive force (pressure-sensitive adhesiveness) of the pressure-sensitive adhesive layer, suppress the high advancement of the adhesive force, and improve the blocking resistance.
The adhesive strength adjusting agent may be used alone or in combination of two or more, and when two or more are used in combination, the combination and ratio thereof should be appropriately selected according to the purpose. Just do it.

The filler may be either an organic filler or an inorganic filler, but is preferably an inorganic filler.
Further, the filler is preferably in the form of particles (fine particles).

Examples of the inorganic filler include silica, zinc oxide, titanium oxide, calcium carbonate, kaolin, active white clay, alumina, starch (starch), glass, silas balloon and the like.

As the adhesive force adjusting agent, at least silica is used as the filler. Silica may be used alone, or silica and a filler other than silica may be used in combination. By using silica, it is possible to enhance the fixability of the ink and facilitate the adjustment of the adhesive force (pressure-sensitive adhesiveness) and the removability.
The silica is preferably amorphous silica. The amorphous silica is preferably in the form of particles (fine particles).

Examples of the amorphous silica include synthetic amorphous silica such as dry silica and wet silica.
Dry silica can be obtained, for example, by a combustion method in which silicon tetrachloride is burned in an oxygen / hydrogen flame. Wet silica can be obtained, for example, by a precipitation method or a gel method in which sodium silicate is neutralized with an inorganic acid, or a sol-gel method in which alkoxysilane is hydrolyzed.
The amorphous silica is preferably wet silica.

The specific surface area of the amorphous silica is preferably 50 to 500 m ² / g, more preferably 100 to 400 m ² / g. When the specific surface area of the amorphous silica is at least the above lower limit value, the amount of ink absorbed is improved, and the printing density in the pressure-sensitive adhesive layer is further improved. Further, when the specific surface area of the amorphous silica is not more than the upper limit value, the incorporation of the adhesive base material into the silica is suppressed, so that the adhesive force of the pressure-sensitive adhesive layer is further improved. The specific surface area of amorphous silica can be measured by a known method such as a permeation method or a gas adsorption method using a gas molecule such as nitrogen.

The amorphous silica preferably has an average particle size of 0.5 to 15 μm, and more preferably 2 to 10 μm. When the average particle size is at least the lower limit, the voids between the amorphous silica particles in the pressure-sensitive adhesive layer are maintained at an appropriate width, and the amount of ink absorbed and the absorption rate are improved. The print density is further improved. Further, when the average particle diameter is not more than the upper limit value, the degree of unevenness on the surface of the pressure-sensitive adhesive layer is reduced, and the print quality is further improved.
In the present specification, the "average particle size" means the median value D50 of the volume cumulative distribution measured by a method using a Coulter counter, unless otherwise specified.

The amount of oil absorbed by the amorphous silica is preferably 100 to 350 mL / 100 g, and more preferably 150 to 300 mL / 100 g. When the oil absorption amount is not more than the lower limit value, the ink absorption amount is further improved, and when the oil absorption amount is not more than the upper limit value, the fluidity of the pressure-sensitive adhesive composition is further improved.

The amorphous silica preferably has a pore volume of 0.5 mL / g or more. When the pore volume is at least the lower limit value, the amount of ink absorbed is improved, and the print density in the pressure-sensitive adhesive layer is further improved. The upper limit of the pore volume is not particularly limited as long as the effect of the present invention is not impaired.

As the amorphous silica, one type may be used alone, two or more types may be used in combination, and when two or more types are used in combination, the combination and ratio thereof should be appropriately selected according to the purpose. Just do it. In the present specification, when one or more of the specific surface area, average particle size, oil absorption amount and pore volume of amorphous silica and other physical properties are clearly different from each other, the type of amorphous silica is used. Are different from each other.

The amorphous silica is preferably blended as a dispersion using a solvent, preferably a polar solvent, as a dispersion medium.
Preferred polar solvents include, for example, water; alcohols such as methanol, ethanol and 2-propanol; chain or cyclic ketones such as acetone, methyl ethyl ketone and cyclohexanone; chain or cyclic ethers such as diethyl ether and tetrahydrofuran. ..
As the solvent (dispersion medium), one type may be used alone, two or more types may be used in combination, and when two or more types are used in combination, the combination and ratio thereof are appropriately selected according to the purpose. do it.
The solvent (dispersion medium) is preferably water or a polar solvent containing water, and more preferably water.

The content (blending amount) of amorphous silica in the dispersion is not particularly limited and may be adjusted as appropriate, but for example, in consideration of handleability and the like, it is preferably 1 to 30% by mass. More preferably, it is 5 to 20% by mass.

When two or more kinds of the amorphous silica are blended as a dispersion, the amorphous silica may be blended one by one as a dispersion, or two or more kinds are dispersed in the same dispersion. You may mix things.

In the pressure-sensitive adhesive composition, the ratio of the compounding amount of silica to the total amount of compounding components other than the liquid medium (total amount of solid compounding components) is preferably 18 to 50% by mass, preferably 27 to 40% by mass. More preferably. When the ratio of the blended amount of silica is equal to or higher than the lower limit value, the print density of the ink on the pressure-sensitive adhesive layer can be adjusted in a better range, and the ratio of the blended amount of silica is equal to or lower than the upper limit value. By being present, the pressure-sensitive adhesive layer can be formed more stably.
By doing so, the structure of the pressure-sensitive adhesive layer can be strengthened, and since the adhesive base easily adheres to the surface of the porous silica, the adhesive force of the pressure-sensitive adhesive layer (Pressure-sensitive adhesiveness) and removability can be easily adjusted.

In the pressure-sensitive adhesive composition, the ratio of the blending amount of silica to 100 parts by mass of the blended amount of the natural rubber-based material used for the adhesive base is preferably 70 to 120 parts by mass, preferably 80 to 110 parts. Parts by mass are more preferable, and more preferably 90 to 105 parts by mass.
When the ratio of the blended amount of silica is equal to or higher than the lower limit value, the print density of the ink on the pressure-sensitive adhesive layer can be adjusted in a better range, and the ratio of the blended amount of silica is equal to or lower than the upper limit value. By being present, the pressure-sensitive adhesive layer can be formed more stably.

In the pressure-sensitive adhesive composition, for example, by using two or more kinds of fillers having different average particle diameters in combination, the surface (adhesive surface) of the pressure-sensitive adhesive layer is easily uneven. The removability of the pressure-sensitive adhesive layer can be improved.

The average particle size of the filler is preferably 0.5 to 30 μm, more preferably 1 to 20 μm, and particularly preferably 2 μm to 15 μm.

Examples of the wax include known waxes such as paraffin wax (solid paraffin).

When the adhesive force adjusting agent is a filler, the pressure-sensitive adhesive composition has a ratio of the blending amount of the adhesive force adjusting agent (filling material) to 100 parts by mass of the blending amount of the adhesive base. It is preferably 1 to 200 parts by mass. When the ratio of the blending amount of the adhesive strength adjusting agent is equal to or more than the lower limit value, the effect of using the adhesive strength adjusting agent is more remarkable, and the proportion of the blending amount of the adhesive strength adjusting agent is the upper limit. When it is less than the value, the pressure-sensitive adhesive layer can be formed more stably.

When the adhesive force adjusting agent is wax, in the pressure-sensitive adhesive composition, the ratio of the blending amount of the adhesive force adjusting agent (wax) to 100 parts by mass of the blending amount of the adhesive base is 1 to 1. It is preferably 20 parts by mass. When the ratio of the blending amount of the adhesive strength adjusting agent is equal to or more than the lower limit value, the effect of using the adhesive strength adjusting agent is more remarkable, and the proportion of the blending amount of the adhesive strength adjusting agent is the upper limit. When it is less than the value, the pressure-sensitive adhesive layer can be formed more stably.

In the pressure-sensitive adhesive composition, the ratio of the blending amount of the adhesive force adjusting agent (filler) other than silica to 100 parts by mass of the blending amount of the adhesive base is, for example, 1 to 60 parts by mass. Can be done.
The ratio of the blending amount of silica in the adhesive strength adjusting agent may be 100% by mass.

(Water-soluble polymer)
The water-soluble polymer improves the strength of the pressure-sensitive adhesive layer and functions as a binder. Examples of the water-soluble polymer include polyvinyl alcohols such as fully saponified polyvinyl alcohol and partially saponified polyvinyl alcohol; modified polyvinyl alcohols such as cationically modified polyvinyl alcohol, anion-modified polyvinyl alcohol, and silanol-modified polyvinyl alcohol; starch oxide; phosphoric acid. Examples thereof include esterified starch; low cons; casein; carboxymethyl cellulose (CMC).
Among these, polyvinyl alcohol is preferable because it causes less decrease in print density and has good offset resistance. Hereinafter, polyvinyl alcohol may be abbreviated as "PVA".

In the pressure-sensitive adhesive composition, the ratio of the blending amount of the water-soluble polymer to 100 parts by mass of the blending amount of the natural rubber-based material used for the adhesive base is preferably 15 to 35, 20 It is more preferably about 30 parts by mass, still more preferably 22 to 26 parts by mass.
When the ratio of the blending amount of the water-soluble polymer is equal to or higher than the lower limit value, the strength of the pressure-sensitive adhesive layer is increased, and the components (for example, silica) in the pressure-sensitive adhesive layer are present on the roll of the sealing device. It can suppress the transition. When the ratio of the blending amount of the water-soluble polymer is not more than the upper limit value, it is possible to suppress an increase in the adhesive force of the pressure-sensitive adhesive layer.

(Other ingredients)
In addition to the adhesive base, the adhesive strength modifier, and the water-soluble polymer, the pressure-sensitive adhesive composition may contain other components that do not fall under these categories.
The other components are not particularly limited as long as the effects of the present invention are not impaired, and examples thereof are known in the field of pressure-sensitive adhesives. Preferred ones are, for example, polyvalent metal salts, surfactants, and adhesives. , Antiblocking agents, stabilizers, solvents, cationic polymers, antioxidants, antifoaming agents, preservatives and the like.
The other components may be used alone or in combination of two or more, and when two or more are used in combination, the combination and ratio thereof may be appropriately selected according to the purpose. ..

The polyvalent metal salt is a salt (for example, sulfate, hydrochloride, nitrate) containing a metal having a valence of 2 or more (divalent, trivalent, ...) When it becomes an ion. If there is, there is no particular limitation.
Preferred polyvalent metal salts include, for example, calcium chloride, magnesium chloride, magnesium sulfate, calcium sulfate, zinc chloride, calcium nitrate, magnesium nitrate, calcium acetate, magnesium acetate and the like.
Among these, calcium chloride and magnesium chloride are more preferable polyvalent metal salts from the viewpoints that the pressure-sensitive adhesive layer can improve the suitability for inkjet printing and have high solubility and safety in water. Be done.

As the polyvalent metal salt, one type may be used alone, two or more types may be used in combination, and when two or more types are used in combination, the combination and ratio thereof should be appropriately selected according to the purpose. Just do it.

In the pressure-sensitive adhesive composition, the ratio of the compounding amount of the polyvalent metal salt to 100 parts by mass of the adhesive base is preferably 5 to 60 parts by mass, preferably 7 to 56 parts by mass. Is more preferable, and 9 to 53 parts by mass is particularly preferable.

Examples of the surfactant include cetyltrimethylammonium chloride, octyldimethylethylammonium ethyl sulfate, lauryldimethylbenzylammonium chloride and the like.

The adhesive is for improving the adhesion between the adhesive base and the base sheet, and preferred examples thereof include styrene-butadiene latex, polyisoprene rubber, acrylonitrile-butadiene rubber, and polyurethane rubber. Can be mentioned.

The antiblocking agent preferably has a low affinity with natural rubber, and more preferably fine particles. Examples of such an anti-blocking agent include starch (starch), synthetic zeolite, microspherical acrylic resin, microspherical polyethylene, alumina, titanium oxide, kaolin, talc and the like.
Among these, the anti-blocking agent is preferably starch because it has a smaller affinity with natural rubber and can realize a higher anti-blocking effect.

The stabilizer is for dispersing and stabilizing a natural rubber latex, and specifically, an anionic surfactant such as a carboxylate, a sulfonate, and a sulfate ester, a glycerin fatty acid ester, and a fatty alcohol ethoxy. Examples thereof include nonionic surfactants such as rates and alkyl glycosides.

The solvent is a liquid medium in the pressure-sensitive adhesive composition and is used for adjusting the viscosity at the time of preparing the pressure-sensitive adhesive composition, and examples thereof include water and an organic solvent.
When preparing the pressure-sensitive adhesive composition, each solid compounding component such as the above-mentioned adhesive base may be blended in a state of being dissolved or dispersed in a liquid medium such as water or an organic solvent. In the present invention, the solvent also includes a liquid medium used for dissolving or dispersing each of such solid compounding components.

The organic solvent is not particularly limited as long as it does not deteriorate the compounding components, but a highly polar organic solvent is preferable, and examples thereof include alcohols such as methanol, ethanol and 2-propanol; acetone, methyl ethyl ketone, cyclohexanone and the like. Chain-shaped or cyclic ketone; Examples thereof include chain-shaped or cyclic ether such as diethyl ether and tetrahydrofuran.

The total amount of the other components other than the solvent in the pressure-sensitive adhesive composition can be arbitrarily adjusted within a range that does not impair the effects of the present invention.
However, from the viewpoint that the effect of the present invention can be obtained more remarkably, the pressure-sensitive adhesive composition comprises the adhesive base and adhesion with respect to the total amount of compounding components other than the liquid medium (total amount of solid compounding components). The ratio of the total amount of the force adjusting agent to be blended is preferably 60% by mass or more, more preferably 65% by mass or more, and particularly preferably 70% by mass or more. On the other hand, the upper limit of the ratio of the total blending amount is not particularly limited and may be 100% by mass.

The pressure-sensitive adhesive composition can be produced by blending an adhesive base and other components (the adhesive force adjusting agent, other components, etc.).

When blending each component, all the components may be added and then mixed, some components may be added sequentially and mixed, or all components may be added sequentially and mixed. Good. Further, the solid component may be added as a solution in which at least a part thereof is dissolved in a solvent or as a dispersion dispersed in a solvent.
The mixing method is not particularly limited, and a method of rotating and mixing a stirrer or a stirring blade or the like; a method of mixing using a mixer, a three-roll roll, a kneader or a bead mill or the like; a method of adding ultrasonic waves and the like, etc. It may be appropriately selected from known methods. If there is an undissolved component, it is preferable to stir until this component is uniformly dispersed.

The temperature at the time of compounding is not particularly limited as long as each compounding component is not deteriorated, but is preferably 10 to 30 ° C. Then, the temperature at the time of blending may be appropriately adjusted according to the type and amount of the blending component so that the mixture obtained by blending has a viscosity that makes it easy to stir.
Further, the blending time is not particularly limited as long as each blending component is not deteriorated, and may be appropriately adjusted according to the type of the blending component and the temperature at the time of blending, but is preferably 1 minute to 24 hours, for example.

The method for applying the pressure-sensitive adhesive composition to the base material sheet is not particularly limited, and for example, known methods such as a printing method and a coating method can be applied.
Examples of the printing method include a gravure printing method, a flexo printing method, a nozzle type (inkprinting type) printing method, a spray printing method, a screen printing method, an offset printing method, a gravure offset printing method, a pad printing method and the like. ..
As the coating method, for example, various coaters such as spin coater, air knife coater, curtain coater, die coater, blade coater, roll coater, gate roll coater, bar coater, rod coater, gravure coater, wire bar and the like are used. The method and the like can be mentioned.

The coating of the pressure-sensitive adhesive composition may be performed once or may be performed in a plurality of times. When the coating is performed in a plurality of times, the pressure-sensitive adhesive composition may be further applied on the dried coating film, or the pressure-sensitive adhesive composition may be further applied on the undried coating film. You may paint the object.

The coating amount (coating amount of solid content) of the pressure-sensitive adhesive composition is 1 to 8 g / m ² .
When the amount of the solid content of the pressure-sensitive adhesive composition applied is at least the above lower limit value, the adhesive force required for the pressure-sensitive adhesive layer can be secured. Therefore, it is possible to prevent the overlapped surface from peeling off at the stage of, for example, transporting or sorting the removable sheet.
When the amount of the solid content of the pressure-sensitive adhesive composition applied is not more than the above upper limit value, it is possible to suppress an increase in the adhesive force of the pressure-sensitive adhesive layer.

The coated pressure-sensitive adhesive composition may be dried, for example, under normal pressure, reduced pressure, and blowing conditions, and may be performed under either an air atmosphere or an inert gas atmosphere. The drying temperature is not particularly limited, and either heat drying or room temperature drying may be used. Then, other drying conditions such as the drying time may be appropriately set according to the drying method.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is usually preferably 1 to 20 μm, and more preferably 3 to 12 μm.

<Print layer>
The shape, color, and the like of the print layer can be arbitrarily selected depending on the intended purpose, and are not particularly limited. For example, the print layer may be composed of only characters, may be composed of only patterns other than characters, or may be composed of a combination of characters and patterns other than characters.

The printing layer uses, for example, an inkjet printing method, a screen printing method, a flexo printing method, an offset printing method, an electrophotographic printing method, a dip printing method, a dispenser printing method, a gravure printing method, and the like. It can be formed by a known printing method such as a gravure offset printing method or a pad printing method, and may be appropriately selected according to the purpose. Further, as the printing method, one method may be applied alone, or two or more methods may be applied in combination.

The thickness of the print layer is not particularly limited, but is usually preferably 0.1 to 50 μm.

As described above, the printing layer may be composed of a single layer or may be composed of a plurality of layers of two or more layers (a layer in which a plurality of layers are laminated). When the print layer consists of a plurality of layers, the plurality of layers may be the same as or different from each other. That is, all layers may be the same, all layers may be different, or only some layers may be different. When the plurality of layers are different from each other, the combination of the plurality of layers is not particularly limited. Here, the fact that the plurality of layers are different from each other is the same as in the case of the above-mentioned base sheet.
When the print layer is composed of a plurality of layers, the total thickness of each layer may be set to be the above-mentioned preferable thickness of the print layer.

The removable sheet preferably has high ink absorbency. The ink absorbability can be evaluated by, for example, the following method.
When black pigment ink is solid-printed (single-color printing) in a size of 2 cm x 2 cm on the surface of a removable sheet using an inkjet printer, and the roll is rolled on the surface of the printing part after 0.1 seconds. The density of the ink transferred to the roll is defined as transfer stain ΔE. The smaller the transfer stain ΔE, the higher the ink absorbability. The transfer stain ΔE is preferably 3.2 or less, for example.

For example, when the removable sheet is a pressure-sensitive crimping postcard on which concealment information is printed and a large number of distribution target persons are printed, fixed information common to all distribution target persons is printed by an offset printing method or the like. A print layer can be formed by a method of printing (printing) and printing (printing) variable information different for each distribution target person by an inkjet printing method or the like. However, this is an example, and the method for forming the print layer is not limited to this.

<Manufacturing method of removable sheet>
Next, a method for producing the removable sheet will be described.
The removable sheet can be produced by a manufacturing method including a pressure-sensitive adhesive layer forming step, a printing layer forming step, a superimposing step, and an adhesive step.
The pressure-sensitive adhesive layer forming step is a step of applying the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer to the surface of the base material sheet to form the pressure-sensitive adhesive layer. ..
The print layer forming step is a step of forming a print layer on the surface of the pressure-sensitive adhesive layer.
The stacking step is a step of stacking the base material sheets on which the pressure-sensitive adhesive layer is formed so that the stacking surfaces face each other.
The bonding step is a step of sandwiching the overlapped base material sheets with a pair of pressurizing bodies and applying pressure to bond the overlapped surfaces to each other so that they can be peeled off again.

<Pressure-sensitive adhesive layer forming process>
As described above, the pressure-sensitive adhesive layer forming step may be carried out by a method of forming a pressure-sensitive adhesive layer by applying the pressure-sensitive adhesive composition to the surface of the base material sheet and drying it. Good.

<Print layer forming process>
As described above, the print layer forming step may be performed by a method of forming a print layer by applying a printing method.

<Overlapping process>
In order to bring the removable sheet into a state in which the overlapping surfaces of the base sheet are adhered to each other by the pressure-sensitive adhesive layer, for example, the removable sheet is folded at a predetermined position and the pressure-sensitive adhesive layer is formed. Make them face each other.

Specific examples of the pressure-sensitive crimping postcard preferable as the removable sheet will be described below with reference to the drawings. FIG. 4 is a front surface development view of the tri-fold postcard obtained by the manufacturing method of one embodiment of the present invention, and FIG. 5 is a back surface development view of the tri-fold postcard shown in FIG.

The tri-fold postcard 21 shown in FIGS. 4 and 5 is composed of a base sheet 2 having a size three times the size of a standard postcard, and is divided into three regions by fold lines 3 (3a, 3b). .. The surface of the left side section area A is printed with address information printing 4 such as a zip code, an address, and an address. Then, the concealment information printing 5 is applied on the back surface of the left side section area A of the base material sheet 2, the front and back sides of the center section area B, and the front surface of the right side section area C. A pressure-sensitive adhesive composition is applied and dried on the front surface and the back surface of the regions A, B, and C so as to cover the concealment information printing 5, and a removable pressure-sensitive adhesive layer 6 is formed. There is.
As shown in FIG. 6, the tri-fold postcard 21 configured in this way is folded into a Z shape at the fold lines 3a and 3b, and the pressure-sensitive adhesive layers 6 on the overlapping surfaces of the respective sections are brought into contact with each other. Overlay.

<Adhesion process>
FIG. 1 is a configuration diagram schematically showing a sealing device (dry sealer) which is a manufacturing device capable of carrying out the method for manufacturing a removable sheet according to an embodiment of the present invention. FIG. 2 is an enlarged configuration diagram showing a part of the sealing device.
The sealing device shown here is provided with a pair of pressure rolls 7 and 8 (pressurized bodies) facing each other so that the roll surfaces 7a and 8a (pressurized surfaces) are not in contact with each other. The pressure rolls 7 and 8 are made of metal, for example, and are arranged in parallel so that the rotation axes are parallel to each other. As the sealing device, for example, "Pressle Multi" (trade name, manufactured by Toppan Forms Co., Ltd.) can be preferably used.

The distance C1 (minimum distance) between the roll surfaces 7a and 8a of the pressure rolls 7 and 8 is the thickness T1 (hereinafter referred to as sheet 10) of the base sheet (for example, tri-fold postcard 21; hereinafter referred to as sheet 10) stacked as described above. It is set to 66 to 90% with respect to 2 and FIG. 6). The interval C1 is preferably 70 to 90% with respect to the thickness T1, and more preferably 75 to 80% with respect to the thickness T1.
When the ratio of the interval C1 to the thickness T1 is equal to or greater than the lower limit value, the adhesive force of the pressure-sensitive adhesive layer can be suppressed within an appropriate range. When the ratio of the interval C1 to the thickness T1 is equal to or less than the upper limit value, the adhesive force required for the pressure-sensitive adhesive layer can be secured, and for example, the releasable sheets are laminated at the stage of transportation, sorting, and the like. It is possible to prevent the surface from peeling off.
The thickness T1 of the sheet 10 can be measured in accordance with JIS P8118-1998.

As shown by the arrows, the pressurizing rolls 7 and 8 can rotate in opposite directions, and the rotational force of the pressurizing rolls 7 and 8 pulls the stacked sheets 10 between the pressurizing rolls 7 and 8 as described above. The sheet 10 is pressed in the thickness direction by being sandwiched between the roll surfaces 7a and 8a of the pressure rolls 7 and 8.
As a result, the overlapping surfaces of the sheet 10 are removably bonded to each other via the pressure-sensitive adhesive layer.

The sealing device may include a plurality of pairs of pressure rolls. For example, the sealing device shown in FIGS. 1 and 2 includes one or a plurality of pairs of pressure rolls in the front stage (upstream side in the transport direction) or the rear stage (downstream side in the transport direction) of the pressure rolls 7 and 8. May be good.
In that case, the above-mentioned numerical limitation regarding the ratio of the pressure roll interval to the sheet thickness is applied to the pressure roll having the smallest interval (for example, the pressure roll located at the most downstream in the transport direction).

The method of folding the removable sheet is not limited to the Z-shaped tri-fold, but may be another folding method such as bi-folding, and is not particularly limited.
It is preferable that the sealing device can adjust the distance between the pressure rolls. As a result, the distance between the pressure rolls can be set within the above range according to the thickness of the removable sheet, so that it is possible to handle a wide variety of removable sheets.

Another example of a pressure-sensitive crimping postcard is a bi-fold postcard that has twice the size of a standard postcard, and this bi-fold postcard is folded along a fold line and is pressure-sensitive in the area to be the overlapping surface. By bringing the adhesive layers into contact with each other and applying pressure, the overlapped surfaces are removably bonded to each other.

In the conventional method for producing a removable sheet, a part of the pressure-sensitive adhesive layer may be easily transferred to a roll or the like of a sealing device. For example, in a tip-glue type removable sheet, silica is added to the pressure-sensitive adhesive layer for the purpose of improving ink fixability, and silica in the pressure-sensitive adhesive layer is applied to a roll or the like of a sealing device. It sometimes adhered. In that case, due to the adhered silica, the pressure when the removable sheet is crimped by the sealing device partially fluctuates, and the adhesive force of the removable sheet is partially excessive or insufficient. It could happen.
If the fixability of silica is improved by increasing the amount of a binder such as a water-soluble polymer in the pressure-sensitive adhesive layer, the transfer of silica can be reduced, but in that case, pressure-sensitive adhesion is particularly carried out in a high temperature and high humidity environment. The adhesive strength of the agent layer was increased, and it was sometimes difficult for the overlapped surfaces to be peeled off again.
Adhesive base (natural rubber, etc.) is exposed on the surface of the pressure-sensitive adhesive layer by gradually infiltrating the base sheet with a binder such as a water-soluble polymer over time. It can be inferred that the cause is that it becomes easier.

In the method for producing a removable sheet, the interval C1 between the pressure rolls 7 and 8 is 66 to 90% with respect to the thickness T1 of the sheet 10. When the ratio of the interval C1 to the thickness T1 is equal to or greater than the lower limit value, it is possible to suppress an increase in the adhesive force of the pressure-sensitive adhesive layer. When the ratio of the interval C1 to the thickness T1 is equal to or less than the upper limit value, the adhesive force required for the pressure-sensitive adhesive layer can be secured, and for example, the releasable sheets are laminated at the stage of transportation, sorting, and the like. It is possible to prevent the surface from peeling off. Therefore, it is possible to suppress the advancement of the adhesive force while maintaining an appropriate adhesive force by the pressure-sensitive adhesive layer.

The increase in adhesive strength can be evaluated based on the following increase rate.
The removable sheet is folded into a test piece, and the test piece is pressed in the thickness direction using a sealing device to bond the overlapped surfaces to each other.
The test piece is stored in a high temperature / high humidity environment (temperature 40 ° C., humidity 90%), and after a lapse of a predetermined time, it is taken out from the environment and subjected to a peeling test according to, for example, JIS K6854 (adhesive peeling adhesive strength test method). T-type peeling is performed using a machine (“Autograph AGH” manufactured by Shimadzu Corporation), and the adhesive strength at this time is measured.
The high advance rate can be calculated as the ratio of the adhesive force to the adhesive force on the first day. For example, the high advance rate on the next day can be calculated as "adhesive strength on the next day / adhesive strength on the first day" * 100. The adhesive strength on the first day is the adhesive strength measured after bonding without being placed in a high temperature / high humidity environment.
The high advance rate 24 hours (1 day) after the start of the test is preferably 200% or less (for example, 100 to 200%).
When the high advance rate is not more than the above upper limit value, the removable surface can be easily re-peeled even when the removable sheet is left in a high temperature / high humidity environment for a long time.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the examples shown below.

[Example 1]
<Manufacturing of removable sheet>
(Manufacturing of pressure-sensitive adhesive composition)
As shown in Table 1, natural rubber latex (39.5% by mass), styrene-butadiene latex (SBR) (3.6% by mass), and amorphous silica (“E200” manufactured by Toso Silica Co., Ltd.) (36.0). Mass%), silanol-modified polyvinyl alcohol (manufactured by Kuraray, PVA25-98R) (9.1% by mass), starch (starch) (5.6% by mass), stabilizer (polyoxyethylene oleyl ether sodium sulfate) (1) .5% by mass), polyvalent metal salt (calcium chloride) (3.6% by mass), antioxidant (0.5% by mass), antifoaming agent (0.4% by mass), preservative (0.2% by mass) A pressure-sensitive adhesive composition containing (% by mass) was produced.
In this pressure-sensitive adhesive composition, the ratio of the blending amount of the natural rubber latex and the styrene-butadiene latex is 11: 1.

(Manufacturing of removable sheet)
Apply the pressure-sensitive adhesive composition to the surface of the base sheet (water resistant paper manufactured by Nippon Paper Industries, Ltd. (basis weight: about 110 g / m ² )) with an air knife coater so that the solid content is 6.0 g / m. It was coated and dried at 150 ° C. to form a pressure-sensitive adhesive layer to obtain a removable sheet similar to that shown in FIG.

(Evaluation of adhesive strength)
The removable sheet is placed in an environment of 23 ° C. and a relative humidity of 50% for 12 hours, and then the removable sheet is formed into a Z shape so that the surfaces of the pressure-sensitive adhesive layers come into contact with each other. It was folded in half to make a test piece.
The thickness of the removable sheet before folding was 158.9 μm, and the thickness of the tri-folded test piece was 476.7 μm. The thickness was measured by a method conforming to JIS P8118-1998.
This test piece was pressed by the roll sealer (sealing device) shown in FIGS. 1 and 2, and the overlapping surfaces of the sheets were adhered to each other. The roll gap (interval between pressure rolls) of the roll sealer was set to 330 μm. The ratio of the roll gap to the thickness of the test piece (hereinafter referred to as the compression ratio) is 69%.

The test piece discharged from the roll sealer was stored in a high temperature and high humidity environment (temperature 40 ° C., humidity 90%). The test piece was taken out from the environment the next day or later, and the humidity was adjusted for 30 minutes in an environment of a temperature of 23 ° C. and a humidity of 50%. Of the two sets of overlapping surfaces, the sheets are peeled off from each other on one side, and the remaining overlapping surface is peeled off according to JIS K6854 (adhesive peeling adhesive strength test method). T-type peeling was performed using "Autograph AGSH" manufactured by Japan, and the adhesive strength at this time was measured. The number of measurements was set to 3, and the average value thereof was calculated.

The high advance rate (%) was calculated based on the measured values. For example, the high advance rate on the day after the start of the test was set to "adhesive strength on the next day / adhesive strength on the first day" * 100. The adhesive strength on the first day is the adhesive strength measured after adjusting the humidity for 20 to 30 minutes in an environment of a temperature of 23 ° C. and a humidity of 50% without placing the product in a high temperature / high humidity environment after bonding.
The results are shown in Table 2 and FIG.

(Evaluation of ink absorbency)
When black pigment ink is solid-printed (single-color printing) in a size of 2 cm x 2 cm on the surface of a removable sheet using an inkjet printer, and the roll is rolled on the surface of the printing part after 0.1 seconds. , The density of the ink transferred to the roll was calculated as the transfer stain ΔE. The smaller the value of the transfer stain ΔE, the higher the ink absorbency. The results are shown in FIG.

[Example 2]
As shown in Table 1, the same as in Example 1 except that the blending amount of the natural rubber latex of the pressure-sensitive adhesive composition is 36.0% by mass and the blending amount of the styrene-butadiene latex is 7.2% by mass. To produce a removable sheet.
In this pressure-sensitive adhesive composition, the ratio of the blending amount of the natural rubber latex and the styrene-butadiene latex is 10: 2.
The obtained releasable sheet was evaluated according to Example 1. The roll gap of the roll sealer was 350 μm. The compression ratio is 73%. The results are shown in Table 2, FIG. 8 and FIG.

[Comparative Example 1]
As shown in Table 1, the same as in Example 1 except that the blending amount of the natural rubber latex of the pressure-sensitive adhesive composition is 32.3% by mass and the blending amount of the styrene-butadiene latex is 10.8% by mass. To produce a removable sheet.
In this pressure-sensitive adhesive composition, the ratio of the blending amount of the natural rubber latex and the styrene-butadiene latex is 9: 3.
The obtained releasable sheet was evaluated according to Example 1. The roll gap of the roll sealer was set to 300 μm. The compression ratio is 63%. The results are shown in Table 2, FIG. 8 and FIG.

As shown in Table 2 and FIG. 8, the releasable sheets of Examples 1 and 2 having compression rates of 69% and 73%, respectively, are compared with the releasable sheets of Comparative Example 1 having a compression rate of 63%. , It was possible to suppress the increase in adhesive strength.
In the removable sheets of Examples 1 and 2, the initial adhesive strength was also sufficiently high.
Further, as shown in FIG. 9, it was confirmed that the ink absorbency of Examples 1 and 2 was as good as that of Comparative Example 1.

In addition, when a removable sheet was produced in the same manner as in Example 1 and pressed and adhered at a compression rate of 90%, the high advance rate on the next day was less than 200%, which was good. In addition, peeling of the overlapping surfaces during transportation hardly occurred.
When a removable sheet was produced in the same manner as in Example 1 and pressed and bonded at a compression rate of 95%, the overlapped surfaces could not be bonded to each other.

The present invention can be used for confidential information recording sheets such as pressure-sensitive crimping postcards.

1,1A ... Removable sheet, 7,8 ... Pressurized roll (pressurized body), 7a, 8a ... Roll surface (pressurized surface), 10 ... Sheet (superposed base material) Sheet), 11a ... Surface of base sheet, 12 ... Pressure-sensitive adhesive layer, 21 ... Tri-fold postcard (removable sheet), 11 ... Base sheet, 12a ... Feeling Surface of pressure adhesive layer, C1 ... Spacing between roll surfaces of pressure roll, T1 ... Thickness of laminated base sheet

Claims (2)

A method for producing a removable sheet, wherein a pressure-sensitive adhesive layer is provided on the surface of the base material sheet, and the overlapping surfaces of the base material sheets can be removably adhered to each other via the pressure-sensitive adhesive layer.
A step of applying a pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer to the surface of the base material sheet to form the pressure-sensitive adhesive layer, and a step of forming the pressure-sensitive adhesive layer.
A step of laminating the base material sheet on which the pressure-sensitive adhesive layer is formed so that the superposed surfaces face each other.
It has a step of sandwiching the overlapped base material sheets with a pair of pressurizing bodies and applying pressure to bond the overlapped surfaces to each other so as to be removable.
The pressure-sensitive adhesive composition contains an adhesive base containing a natural rubber-based material and a diene-based rubber material , an adhesive force adjusting agent containing silica, and a water-soluble polymer.
The ratio (mass basis) of the blending amount of the natural rubber-based material and the diene-based rubber material is 11: 1 to 5: 1.
The water-soluble polymer contains polyvinyl alcohol and contains
In the step of forming the pressure-sensitive adhesive layer, the coating amount of the pressure-sensitive adhesive composition is set to 1 to 8 g / m ² , and the base sheets are overlapped on both surfaces of the base sheets. The pressure-sensitive adhesive layer is formed in each corresponding region,
Manufacture of a removable sheet in which the distance between the pressure surfaces of the pair of pressurizing bodies is 66 to 90% of the thickness of the overlapped base sheet in the step of adhering the overlapped base sheets. Method. The method for producing a releasable sheet according to claim 1 , wherein the polyvinyl alcohol is silanol-modified polyvinyl alcohol .

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