JP6096559B2 - Removable sheet - Google Patents

Description

  The present invention relates to a releasable sheet provided with a pressure-sensitive adhesive layer that can be re-peeled.

A pressure-sensitive adhesive layer having removability is formed on the surface of a sheet to be a base material, and the sheets are pressure-bonded to each other via this adhesive layer, and the releasable sheet bonded is used in various applications. Widespread in society.
A typical example of such a releasable sheet is a pressure-sensitive pressure-bonding postcard, which is widely used in a postcard system having confidentiality.

  A postcard system with confidentiality can be used in various superposition modes, for example, folding postcards containing various information such as personal requirements, print information, print information, etc. Adhering in a peelable manner and concealing various information, it is mailed, and the recipient reads the concealment information again by peeling the overlapping surface. Such a friendly postcard system has become indispensable for its convenience.

  As such a releasable sheet, for example, a non-releasable adhesive base comprising a block copolymer having an aromatic ring-containing vinyl compound and an ethylenically unsaturated monomer having 2 to 3 carbon atoms as constituent units ( A) and a pressure-sensitive adhesive layer composed of a particulate filler (B) showing non-affinity for (A) are disclosed (see Patent Document 1).

  However, the releasable sheet disclosed in Patent Document 1 is a roll or plate in a state in which a pressure-sensitive adhesive layer is formed in the manufacturing process or the process of printing or printing information on the surface of the manufactured sheet. Pressure-sensitive adhesive layer is not sufficient in wear resistance when it is passed through a sheet-like member (hereinafter abbreviated as a plate or the like) and conveyed, and is in contact with the surface of a plate or the like. There was a problem that a part of was dropped from the sheet. In such a case, the dropped pressure-sensitive adhesive layer may cause a process failure when the sheet is transported or printed or printed on the sheet, and the quality of the releasable sheet itself is deteriorated. End up.

  As a solution to such problems, a releasable sheet provided with a pressure-sensitive adhesive layer formed using a pressure-sensitive adhesive composition comprising an adhesive base and fluororesin fine particles is blended. It is disclosed (see Patent Document 2). This re-peelable sheet uses fluororesin fine particles, so that the pressure-sensitive adhesive layer is excellent not only in re-peelability but also in abrasion resistance. Generation | occurrence | production and the quality fall of removable sheet itself are suppressed.

JP 2006-299256 A JP 2011-144212 A

  However, in the releasable sheet disclosed in Patent Document 2, a fluororesin that is considered to be derived from the pressure-sensitive adhesive layer adheres to a member such as a roll necessary for conveyance in the step of conveying the sheet, and friction resistance There is a problem in that it becomes difficult to feed (supply) when the value becomes too low.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a releasable sheet having a pressure sensitive adhesive layer that is removable and excellent in wear resistance, and has good feed characteristics. .

To solve the above problem,
The present invention is a releasable sheet in which the overlapping surfaces of the sheets are removably bonded with a pressure-sensitive adhesive layer, and the adhesive layer includes an adhesive base, fluororesin fine particles, The pressure-sensitive adhesive composition is formed by using a pressure-sensitive adhesive composition comprising hard fine particles made of a material having a larger Rockwell hardness value than the fluororesin. The releasable sheet is characterized in that the mass ratio of [the blending amount of the hard fine particles (part by mass)] / [the blending amount of the fluororesin fine particles (part by mass)] is 1.3 or more. .
In the releasable sheet of the present invention, the hard fine particles are preferably acrylic resin fine particles.

  ADVANTAGE OF THE INVENTION According to this invention, the releasable sheet | seat which is provided with the pressure sensitive adhesive layer excellent in the abrasion resistance which can be re-peeled and has favorable feed characteristics is provided.

It is a surface development view of the tri-fold postcard according to the present invention. It is a back surface expanded view of the postcard shown in FIG. It is sectional drawing in the XX line of FIG. It is a figure explaining the state at the time of folding the postcard shown in FIG. It is a surface expansion | deployment figure of the bifold postcard which concerns on this invention. FIG. 6 is a developed rear view of the postcard shown in FIG. 5. It is a figure explaining the state at the time of folding the postcard shown in FIG. It is a surface expanded view of the partial bifold postcard which concerns on this invention. It is a back surface expanded view of the postcard shown in FIG. It is a figure explaining the state at the time of folding the postcard shown in FIG.

The releasable sheet according to the present invention has a releasability in which the overlapping surfaces of the sheets are releasably bonded with a pressure-sensitive adhesive layer (hereinafter sometimes simply referred to as “adhesive layer”). A pressure-sensitive adhesive in which the adhesive layer is a mixture of an adhesive base, fluororesin microparticles, and hard microparticles made of a material having a larger Rockwell hardness value than the fluororesin The composition is formed using an agent composition (hereinafter, sometimes simply abbreviated as “composition”). In the composition, the amount of the hard fine particles is greater than or equal to the amount of the fluororesin fine particles. It is characterized by being.
In the composition, the hard particles are selected as a component to be used in combination with the fluororesin fine particles, and the releasability and wear resistance of the adhesive layer are impaired by making the blending amount of the hard microparticles more than the blending amount of the fluororesin microparticles. Instead, the removable sheet has good feed characteristics. In this specification, the “feed characteristic” means a property that can supply (feed) the removable sheet without any stagnation without any abnormality such as slippage in an apparatus that handles the removable sheet such as a printer. To do.

<Composition for pressure sensitive adhesive>
(Adhesive base)
The adhesive base may be a known one, and specific examples thereof include natural rubber, modified rubber obtained by modifying natural rubber, synthetic rubber, and the like, and more specifically, an organic solvent type using an organic solvent. Examples thereof include water-based materials using water as a medium, radiation-curing materials that are cured by radiation such as ultraviolet rays, and heat-curing materials that are cured by heating. In the present specification, unless otherwise specified, 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. .
Among these, the adhesive base is preferably water-based, and more preferably a natural rubber-based aqueous emulsion type. In the case of a water-based adhesive base, a composition such as an emulsion using the adhesive base has low volatility, the application amount can be easily adjusted, and the suitability for application to the sheet surface becomes better. Further, since the composition is water, the composition is harmless to the human body, is not flammable, and does not require special equipment such as explosion-proof equipment for the coating process and the drying process.

  Examples of the natural rubber-based aqueous emulsion-type adhesive base include those known as natural rubber-based adhesive bases. Specifically, latex containing natural rubber as a main component (natural rubber latex); acidic A modified latex mainly composed of a modified rubber obtained by modifying the natural rubber, such as a latex, a depolymerized latex, a vulcanized latex, or a grafted natural rubber latex; a styrene-rich SBR latex with respect to the natural rubber latex or the modified latex And a mixture containing an appropriate amount of one or more selected from the group consisting of polystyrene emulsion and styrene / acrylic copolymer emulsion. The monomer or oligomer used for the grafting of natural rubber can be arbitrarily selected according to the purpose as long as it has a polymerizable group, and if it is a monomer, it is polymerizable such as alkyl ester of (meth) acrylic acid, styrene, etc. What has an unsaturated double bond can be illustrated. Here, the alkyl ester is preferably a methyl ester or an ethyl ester.

As a natural rubber-based aqueous emulsion type adhesive base, modified rubber obtained by graft polymerization of methyl methacrylate (MMA) on natural rubber, particularly from the viewpoint of blocking resistance, heat resistance, wear resistance, etc. A modified latex containing as a main component, a modified latex containing as a main component a modified rubber obtained by graft polymerization of styrene and methyl methacrylate on natural rubber is preferred.
Preferred examples of the modified rubber obtained by graft polymerization of methyl methacrylate on natural rubber include those obtained by graft polymerization of 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 polymerization of styrene and methyl methacrylate on natural rubber is 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 thing can be illustrated.

  An adhesive base may be used individually by 1 type, and may use 2 or more types together. When two or more kinds are used in combination, their combination and ratio may be appropriately selected according to the purpose. However, when using 2 or more types together, it is preferable to use the same system.

  In the composition, the ratio of the blending amount of the adhesive base to the total amount of solid blending components is preferably 30 to 80% by mass, and more preferably 45 to 70% by mass. Adhesive strength of the adhesive layer is further improved by the ratio of the blending amount of the adhesive base being equal to or higher than the lower limit value, and the proportion of the blending amount of the adhesive base is equal to or lower than the upper limit value. The abrasion resistance of the agent layer and the feed characteristics of the removable sheet described later are further improved.

(Fluorine resin fine particles)
The fluororesin fine particles are fine particles made of a fluororesin and function as a filler and at the same time impart excellent wear resistance to the adhesive layer formed from the composition.

The fluororesin may be a resin having a fluorine atom, and is preferably a perfluoro resin such as polytetrafluoroethylene (PTFE); polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), polyfluoride. Partially fluorinated resins such as vinyl fluoride (PVF); perfluoroalkoxy fluororesin (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer, PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), ethylene・ Fluororesin copolymers such as tetrafluoroethylene copolymer (ETFE), ethylene / chlorotrifluoroethylene copolymer (ECTFE), tetrafluoroethylene / perfluorodioxole copolymer (TFE / PDO), etc. It can be illustrated.
Among these, the fluororesin is more preferably a perfluoro resin, and particularly preferably PTFE.

  The fluororesin preferably has a weight average molecular weight of 5,000 to 10,000,000.

  The fluororesin may be only one kind or two or more kinds. That is, fluororesin fine particles composed of a kind of fluororesin may be used alone, or two or more fluororesin microparticles composed of a kind of fluororesin and different from each other may be used in combination. When two or more kinds of fluororesins are used, the combination and ratio of these fluororesins may be appropriately adjusted according to the purpose.

The average particle diameter of the fluororesin fine particles is preferably 3 to 100 μm, and more preferably 5 to 80 μm. The particle diameter of the fluororesin fine particles may be distributed, and the degree of distribution at this time is not particularly limited, but the particle diameter is preferably 1 to 400 μm, more preferably 2 to 320 μm. . When the average particle diameter or the particle diameter is not less than the lower limit, the wear resistance of the adhesive layer is further improved, and when the average particle diameter or the particle diameter is not more than the upper limit, the adhesive force of the adhesive layer And the feed characteristics of the releasable sheet are further improved.
The average particle diameter of the fluororesin fine particles is determined by, for example, the method described in Examples described later, and the average particle diameter of various fine particles other than the fluororesin fine particles is also determined by the same method.

  In the composition, the ratio of the amount of the fluororesin fine particles to the total amount of the solid compounding components is preferably 0.1 to 20% by mass, more preferably 1 to 20% by mass, It is especially preferable that it is -12 mass%. When the ratio of the blending amount of the fluororesin fine particles is not less than the lower limit, the wear resistance of the adhesive layer is further improved, and the ratio of the blending amount of the fluororesin fine particles is not more than the upper limit, The adhesive strength of the layer and the feed property of the releasable sheet are further improved.

(Hard fine particles)
The hard fine particles are made of a material having a larger Rockwell hardness value than the fluororesin constituting the fluororesin fine particles. Here, the Rockwell hardness has three types of scales of R, L, and M, but comparison of the Rockwell hardness with the fluororesin needs to be performed on the same scale.

The hard fine particles function as a filler and at the same time improve the feed characteristics of the releasable sheet.
The material of the hard fine particles (that is, the material having a larger Rockwell hardness value than the fluororesin) is not particularly limited as long as the above conditions are satisfied, and may be either an organic material or an inorganic material. Examples thereof include acrylic resins such as polymethyl methacrylate (PMMA); polypropylene (PP); alumina (aluminum oxide); glass; calcium carbonate. Here, the acrylic resin is a kind of a polymer of (meth) acrylic acid ester or a copolymer of two or more kinds of (meth) acrylic acid ester. In this specification, “(meth) acrylic acid” Is a concept encompassing both “acrylic acid” and “methacrylic acid”.
Among these, the hard fine particles are preferably made of an organic material.

  The material of the hard fine particles may be only one type or two or more types. That is, hard fine particles composed of one kind of material may be used alone, or two or more kinds of hard fine particles composed of one kind of material and having different materials may be used in combination. When the material of the hard fine particles is two or more kinds, the combination and ratio of these materials may be appropriately adjusted according to the purpose.

  The average particle size of the hard fine particles is preferably 5 to 60 μm, and more preferably 10 to 30 μm. When the average particle size of the hard fine particles is equal to or larger than the lower limit, the feed property of the releasable sheet is further improved, and when the average particle size of the hard fine particles is equal to or smaller than the upper limit, the adhesive force of the adhesive layer Will be improved.

In the composition, the blending amount of the hard fine particles is not less than the blending amount of the fluororesin fine particles, and is preferably larger than the blending amount of the fluororesin fine particles. By doing in this way, the feed characteristic of a releasable sheet improves. And, since the feed property of the releasable sheet is further improved, in the composition, the mass ratio of the blended amount of the hard fine particles to the blended amount of the fluororesin fine particles ([the blended amount of hard fine particles (parts by mass)] / [ The blending amount (parts by mass) of the fluororesin fine particles] is preferably 1.1 or more, more preferably 1.3 or more, and particularly preferably 1.5 or more.
Further, since the adhesive strength of the adhesive layer is further improved, in the composition, the mass ratio of the hard fine particles to the fluorine resin fine particles is preferably 10.0 or less, 7.5 More preferably, it is more preferably 5.0 or less.

(Other ingredients)
In addition to the adhesive base, the fluororesin fine particles, and the hard fine particles, the composition may further contain other components that do not fall within the scope of the effects of the present invention.
Examples of the other components include fine particles other than the fluororesin fine particles and hard fine particles, additives, and solvents.

  The other fine particles are mainly composed of a fluororesin as a main material, and a material other than a material having a Rockwell hardness value larger than that of the fluororesin. Specific examples of such a material include various starches (starch) and polyethylene. And silica, shirasu balloon, natural zeolite, synthetic zeolite, zinc oxide, titanium oxide, kaolin, activated clay and the like. Among these, starch (starch) and silica are preferable as the material of the other fine particles. For example, by using silica, the strength of the adhesive layer is increased, and the adhesive base easily adheres to the filler surface due to its porous property, so the adhesive force and removability can be adjusted more easily. it can. In addition, even when printing on the adhesive layer using a non-impact printer method that requires the use of silicone oil, silica absorbs the silicone oil, so the effect of suppressing a decrease in the adhesive strength of the adhesive layer due to the silicone oil becomes higher. .

The other fine particles preferably have an average particle diameter of 0.01 to 30 μm, more preferably 1 to 20 μm, and particularly preferably 2 to 15 μm.
The other fine particles are preferably used in combination of two or more kinds having different average particle diameters. By doing in this way, it becomes easy to form an unevenness | corrugation in the adhesive bond layer surface, As a result, removability improves more, without impairing the adhesive force of an adhesive bond layer.

  The material of the other fine particles may be one kind or two or more kinds. That is, other fine particles made of one kind of material may be used alone, or two or more kinds of other fine particles made of one kind of material and having different materials may be used in combination. In the case where there are two or more materials of the other fine particles, the combination and ratio of these materials may be appropriately adjusted according to the purpose.

  In the composition, the ratio of the amount of the other fine particles to the total amount of the solid compounding components can be arbitrarily adjusted according to the type and purpose of the other fine particles. For example, the ratio of the total amount of starch (starch) fine particles and silica fine particles to the total amount of solid compounding components is preferably 5 to 40% by mass, and more preferably 10 to 30% by mass. When the ratio of the total amount of these fine particles is not less than the above lower limit value, the effect of using these fine particles is sufficiently obtained, and the ratio of the total amount of these fine particles is not more than the above upper limit value. The effect of the present invention is further improved.

  The additive may be a known one that is usually used in the field of pressure-sensitive adhesives. Specifically, a tackifier, a viscosity modifier, an anti-aging agent, a stabilizer, a colorant, a preservative, an antioxidant, Examples include antifoaming agents and antifungal agents. From these, one or more desired components can be blended in any amount depending on the purpose.

  For example, as will be described later, other components other than the solvent such as the adhesive base, fluororesin fine particles, hard fine particles, and other fine particles may be blended as a dispersion using various solvents at the time of preparing the composition. . Examples of the solvent in the other components include the dispersion medium at this time and various solvents used for adjusting the viscosity of the composition, and more specifically, water and various organic solvents.

As said water, ion-exchange water is preferable.
The organic solvent is not particularly limited as long as it does not deteriorate the compounding components, but is preferably a highly polar organic solvent, specifically, an alcohol such as methanol, ethanol, 2-propanol; acetone, methyl ethyl ketone, cyclohexanone, etc. Examples of chain or cyclic ketones include chain or cyclic ethers such as diethyl ether and tetrahydrofuran.
The said organic solvent may be used individually by 1 type, and may use 2 or more types together. When two or more kinds are used in combination, their combination and ratio may be appropriately selected according to the purpose.

  The solvent is preferably water or a mixed solvent of water and a highly polar organic solvent, and the mixed solvent is more preferable as the ratio of water is higher. And as said solvent, water is especially preferable.

  In the composition, the blending amount of the solvent may be appropriately adjusted in consideration of the type of blending component and the like, but is 25 to 400 parts by weight with respect to 100 parts by weight of the total amount of solid blending components. Preferably, it is 65 to 250 parts by mass. When the blending amount of the solvent is not less than the lower limit, the composition can be handled more easily, and when the blending amount of the solvent is not more than the upper limit, the adhesive strength of the adhesive layer is further improved.

  In the composition, the total amount of the other components other than the solvent can be arbitrarily adjusted within a range not impairing the effects of the present invention.

<Method for producing pressure-sensitive adhesive composition>
The composition can be produced by blending the adhesive base, fluororesin fine particles, hard fine particles, and other components as required.
At the time of blending each component, all the components may be added and then mixed, or some components may be mixed while being added sequentially, or all components may be mixed while being added sequentially. Good. The solid component may be added as a dispersion in which at least a part thereof is dispersed in a solvent.
The mixing method is not particularly limited, and may be appropriately selected from known methods such as a method of mixing by rotating a stirrer or a stirring blade, a method of mixing using a mixer, a method of adding ultrasonic waves, and the like. . And it is preferable to stir until the component which is not melt | dissolving disperse | distributes uniformly.

  The temperature at the time of compounding is not particularly limited as long as each compounding component does not deteriorate, but it is preferably 15 to 30 ° C. Moreover, what is necessary is just to adjust a mixing time suitably according to the kind of compounding component, and the temperature at the time of a mixing | blending, For example, it is preferable that it is 0.5 to 24 hours.

<Removable sheet>
In the releasable sheet according to the present invention, the overlapping surfaces of the sheets are bonded to each other so as to be peeled off by the adhesive layer formed using the composition.
The said sheet | seat is a base material which forms an adhesive bond layer, and an adhesive bond layer can be formed by apply | coating the said composition to the predetermined location of a sheet | seat, and making it dry, for example.

  The said sheet | seat can be arbitrarily selected according to the intended purpose of a releasable sheet. For example, as a preferable releasable sheet, a pressure-sensitive pressure-bonding postcard when paper is used as the substrate can be exemplified.

  The material of the sheet is not particularly limited as long as the composition can be applied, and can be arbitrarily selected according to the purpose. Specific examples of preferred materials for the sheet include paper such as base paper, art paper, coated paper, cast coated paper, resin coated paper, and synthetic paper; polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyvinyl acetate, acrylic Resin, AS resin, ABS resin, polyamide, polyacetal, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyphenylene sulfide, polysulfone, polycarbonate, epoxy resin, melamine resin, phenol resin, Examples include synthetic resins such as urea resin, polyurethane, and polyimide.

  The sheet may be composed of a single layer, or may be composed of two or more layers (multiple layers are laminated). And when it consists of multiple layers, the material of these multiple layers may be only 1 type, 2 or more types, and when it is 2 or more types, the combination and ratio of these materials can be arbitrarily selected according to the objective.

When the material of the sheet is the synthetic resin, the surface of the sheet is preferably subjected to a surface treatment such as a mat treatment or a corona treatment.
In the present invention, it is preferable that the material of the application surface of the composition is paper.

  Although the thickness of a sheet | seat is not specifically limited, Usually, it is preferable that it is 50-200 micrometers, and it is more preferable that it is 80-150 micrometers. When the sheet is composed of a plurality of layers, the total thickness of the plurality of layers is preferably in the above numerical range.

  A method for coating the composition on the sheet is not particularly limited, and a known method can be appropriately used. Preferred methods include an air knife coater, a curtain coater, a die coater, a blade coater, a roll coater, and a gate roll coater. Examples thereof include various coaters such as bar coaters, rod coaters, and gravure coaters; and a method of coating using an apparatus such as a wire bar.

  The composition may be applied once or may be divided into a plurality of times. When performing by dividing into multiple times, either a method of further applying on a dried coated surface or a method of further applying on a non-dried coated surface may be used.

The coating amount of the composition may be appropriately adjusted in consideration of the solid content concentration of the composition. Usually, preferably 1 to 30 g / ^{m 2} is coated amount of solids, more preferably 1.5 to 20 / ^{m 2,} particularly preferably such that 2 to 15 g / ^{m 2,} coating compositions Adjust the amount. When the coating amount of the solid content is equal to or higher than the lower limit value, the adhesive force of the adhesive layer is further improved, and when the coating amount of the solid content is equal to or lower than the upper limit value, the removability is better. Become.

  The coated composition may be dried, for example, under normal pressure, reduced pressure, or blowing conditions, or may be performed under air or an inert gas atmosphere. Also, the drying temperature is not particularly limited, and may be either heat drying or room temperature drying. And other drying conditions, such as drying time, should just be set suitably according to the drying method.

  The adhesive layer preferably has a thickness of 3 to 40 μm, and more preferably 5 to 30 μm. By being in such a range, the same effect as the case where the coating amount of the solid content of the composition is limited as described above can be obtained.

  The adhesive layer has a uniform composition regardless of the site by being formed using the composition in which the components are uniformly dissolved or dispersed. Therefore, when considering an arbitrary cross section other than the surface (adhesive surface) of the adhesive layer and paying attention to a specific component, the concentration of the component in the cross section is the same as the concentration in the adhesive surface, or It is a very close value that can be regarded as the same. Therefore, for example, when focusing on fine particles such as fluororesin fine particles, hard fine particles, and other fine particles as a component, and observing each surface looking down from above (ie, in plan view) as an index representing the amount thereof When the area values of these contained components are adopted, the ratio of the total area value of the contained components in each surface is also the same in the cross section and the adhesive surface, or very close to the extent that can be regarded as the same. It becomes the value. Thus, since the concentration of the contained component in the cross section and the adhesive surface is the same, when attention is paid to two or more contained components, the concentration ratio of these contained components (for example, the fluororesin with respect to the concentration of the hard fine particles) Similarly, the ratio of the concentration of fine particles ([concentration of fluororesin fine particles] / [concentration of hard fine particles]) is the same in the cross section and the adhesive surface.

  The releasable sheet according to the present invention has good feed characteristics. The reason for this is that since hard fine particles exist on the surface of the adhesive layer formed from the composition, when the releasable sheet is fed to various devices, the members in the device and the adhesive layer are in contact with each other. However, the area value of the contact surface is reduced, the movement (transfer) from the fluororesin adhesive layer, which is a soft material, to the member is suppressed, and an excessive decrease in the frictional resistance value in the member is suppressed. It is estimated that. In addition to being hard, the hard fine particles have a high affinity with the adhesive base. Therefore, even if the member in the apparatus and the adhesive layer come into contact with each other, the movement from the adhesive layer to the member hardly occurs from the beginning.

  When information such as characters is recorded on the overlapping surface of the sheet, the information may be recorded on a sheet serving as a base material or may be recorded on an adhesive layer. The information recording process may be performed at a timing suitable for the recording part of the information. For example, after forming the adhesive layer after recording information on the sheet, or after forming the adhesive layer on the sheet Information may be recorded on it.

  The color and transparency of the adhesive layer may be appropriately adjusted in consideration of the information recording site. For example, when information is recorded on a sheet, the adhesive layer is preferably as the color is lighter and the transparency is higher, and is particularly preferably colorless and transparent. On the other hand, this is not the case when information is recorded on the adhesive layer. What is necessary is just to adjust the color and transparency of an adhesive bond layer suitably with the kind and quantity, etc. of the compounding component of the said composition.

  Specific examples of pressure-sensitive pressure-bonding postcards preferable as the re-peelable sheet will be described below with reference to the drawings. 1 is a developed front view of a tri-fold postcard according to the present invention, FIG. 2 is a developed rear view of the postcard shown in FIG. 1, FIG. 3 is a cross-sectional view taken along the line XX of FIG. It is a figure explaining the state at the time of folding. 5 is a developed front view of a half-folded postcard according to the present invention, FIG. 6 is a developed rear view of the postcard shown in FIG. 5, and FIG. 7 is a diagram for explaining a state when the postcard shown in FIG. 8 is a front development view of a partially folded postcard according to the present invention, FIG. 9 is a rear development view of the postcard shown in FIG. 8, and FIG. 10 is a diagram for explaining a state when folding the postcard shown in FIG. .

A tri-fold postcard 1 shown in FIGS. 1 to 3 is composed of a base sheet 2 having a size three times the standard postcard size, and is divided into three regions by folding lines 3a and 3b. On the surface of the left partition area A, destination information printing 4 such as a zip code, a destination name, and an address is applied. And the composition for pressure sensitive adhesives is apply | coated and dried to the whole surface of the center division area B and the right division area C of the base sheet 2, and the whole back surface of the left division area A and the center division area B, and it peels again. A possible pressure sensitive adhesive layer 6 is formed. A concealment information print 5 is applied on the adhesive layer 6 on the back surface of the left partition area A, the front and back surfaces of the central partition area B, and the front surface of the right partition area C. As shown in FIG. 4, the tri-fold postcard 1 configured as described above is folded into a Z shape at the fold lines 3 a and 3 b, and the adhesive layers 6 on the overlapping surfaces of the respective sections are brought into contact with each other. When the pressure is applied, the overlapping surfaces of the respective sections are bonded to each other through the adhesive layer 6 so as to be detachable.
In addition, although the case where the adhesive layer was formed in a total of four compartments for each of the front and back two compartments was explained here, what compartment (surface) the adhesive layer is formed on can be arbitrarily set according to the purpose, for example, The adhesive layer may be formed on the six compartments of the front and back whole compartments (surfaces). The same applies to other embodiments described below.

  A bi-fold postcard 11 shown in FIGS. 5 and 6 is composed of a base sheet 2 having a size twice as large as a standard postcard size, and is divided into two regions by a fold line 3 at the center. On the surface of the left partition area D, destination information printing 4 such as a postal code, a destination name, and an address is applied. And the composition for pressure sensitive adhesives is apply | coated and dried on the whole back surface of the left side division area D and the right side division area E of the base sheet 2, and the pressure sensitive adhesive layer 6 which can be removed again is formed. Then, concealment information printing 5 is applied on the adhesive layer 6 on the back surface of the left partition area D and the right partition area E. As shown in FIG. 7, the double-folded postcard 11 configured in this way is folded at the fold line 3 as shown in FIG. When the adhesive layers 6 are brought into contact with each other and a pressure is applied, the overlapping surfaces of the respective sections are bonded to each other through the adhesive layer 6 so as to be detachable.

  A partially folded postcard 21 shown in FIGS. 8 and 9 is composed of a base sheet 2 having a size 1.5 times the standard postcard size, and is divided into two left and right regions having different sizes by a folding line 3. . On the surface of the left partition area F, destination information printing 4 such as a zip code, a destination name, and an address is applied. Then, the pressure sensitive adhesive composition is applied and dried on the entire back surface of the right partition region G of the base sheet 2 and on the partial back surface of the partition region F that is overlapped when the partition region G is folded at the fold line 3. Thus, a pressure-sensitive adhesive layer 6 that can be re-peeled is formed. Then, concealment information printing 5 is performed on the adhesive layer 6 on the back surface of the right partition region G and the partial back surface of the left partition region F. As shown in FIG. 10, the partially folded postcard 21 configured in this manner is folded at the fold line 3 and is formed on the back surface and the left partitioned area of the right partitioned area G to be the overlapping surface, as shown in FIG. 10. When the adhesive layers 6 on the partial back surface of F are brought into contact with each other and a pressure is applied, the overlapping surfaces of the respective sections are bonded to each other through the adhesive layer 6 so as to be removable.

  In these embodiments, the example in which the concealment information print 5 is applied on the adhesive layer 6 has been shown. However, the concealment information print 5 can also be applied directly to the corresponding portion of the base sheet 2, and the recipient can overlap it. By re-peeling the mating surfaces, the concealment information 5 formed under the adhesive layer 6 can be read. However, from the viewpoint of ease of reading, it is preferable to perform concealment information printing 5 on the adhesive layer 6.

  The releasable sheet according to the present invention is suitable as a confidential information recording sheet in which various types of information such as characters and images are recorded on the overlapping surface of the sheets. In addition, although the pressure-sensitive pressure-bonding postcard has been described here, by appropriately selecting the configuration other than the composition, such as the material and shape of the sheet serving as the base material, the formation site of the adhesive layer, etc., it can be used in various applications. Applicable.

  The re-peelable sheet according to the present invention has good feed characteristics due to the use of the composition, and can be fed without stagnation without any abnormalities such as slippage in an apparatus for handling the sheet. Moreover, since the said adhesive bond layer is excellent in abrasion resistance in addition to removability, a releasable sheet can be manufactured with favorable quality by a stable manufacturing process.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the following examples.
For the fine particles (fluororesin fine particles, hard fine particles, and other fine particles) used in the following Examples and Comparative Examples, the Rockwell hardness and average particle diameter of the material were measured by the following methods.

<Measurement of Rockwell hardness>
Based on ASTM D-785, the Rockwell hardness was measured on an R scale.
<Measurement of average particle diameter>
Using a laser diffraction / scattering particle size analyzer ("MT3300" manufactured by Nikkiso Co., Ltd.), the particle refractive index is 1.81, the solvent refractive index is 1.333, and the 50% frequency particle diameter (median diameter) is calculated on a volume basis. The average particle diameter was determined.

<Manufacture of releasable sheet and evaluation of wear resistance and adhesive strength of pressure-sensitive adhesive layer>
[Example 1]
(Production of pressure-sensitive adhesive composition)
100 parts by mass (solid content) of natural rubber (NR) is graft-polymerized by 25 parts by mass of styrene and methyl methacrylate (hereinafter sometimes abbreviated as “MMA”) by a known method to obtain a solid content of 49 A mass% styrene MMA copolymer aqueous latex was prepared.
Next, a silica fine particle dispersion in which silica fine particles (“Nipsil E200” manufactured by Tosoh Silica Co., Ltd., average particle size 6.5 μm) are dispersed in ion-exchanged water so as to have a solid content of 16% by mass is prepared in advance. 125 parts by mass (20 parts by mass of solids) of this silica fine particle dispersion was added to 204.1 parts by mass (100 parts by mass of solids) of the aqueous styrene MMA copolymer latex obtained above, and 5 Stir and mix at ˜40 ° C. to obtain a first mixture.
Subsequently, polytetrafluoroethylene (hereinafter sometimes abbreviated as “PTFE”) fine particles (“TFW-500” manufactured by Seishin Enterprise Co., Ltd., average particle diameter of 58.4 μm) so that the solid content is 35.7% by mass. In this way, a PTFE fine particle dispersion in which a particle size distribution of 10.1 to 296.0 μm and a weight average molecular weight of 10,000 or less) is dispersed in ion-exchanged water is prepared in advance, and the total amount of the first mixture obtained above is adjusted. On the other hand, 11.2 parts by mass (4 parts by mass of solid content) of this PTFE fine particle dispersion was added and stirred and mixed at 5 to 40 ° C. to obtain a second mixed solution.
Next, 5 parts by mass of starch ("ACTISIZECWH" manufactured by Rocket Corporation, average particle diameter 20 μm), and fine particles of polymethyl methacrylate (hereinafter sometimes abbreviated as "PMMA") ("Gantz Pearl GM-2001 manufactured by Aika Industry Co., Ltd.) ”, 15 parts by mass of average particle diameter 19.5 μm) and 21 parts by mass of other thickeners and other additives (solid content) were added to the total amount of the second liquid mixture obtained above. The composition for pressure-sensitive adhesive was produced by stirring and mixing at ˜40 ° C. Table 1 shows the amounts of the adhesive base, the fluororesin fine particles, and the hard fine particles, which are essential components. In Table 1, the “blending amount (mass%)” of the essential blending component (solid) is the ratio of the blending amount of the solid component to the total amount of the solid blending component in the pressure-sensitive adhesive composition. Means.

(Manufacture of releasable sheet)
On one side of a paper sheet (manufactured by Nippon Paper Industries Co., Ltd.) having a thickness of 130 to 134 μm, the obtained composition is applied using a wire bar so that the solid content is about 6 g / m ^2. And dried at 105 ° C. to form a pressure-sensitive adhesive layer having a thickness of 9 to 18 μm. And the sheet | seat in which this adhesive bond layer was formed was cut | disconnected to the magnitude | size of 25 mm x 250 mm, and the releasable sheet was obtained.

(Evaluation of wear resistance of pressure-sensitive adhesive layer)
Using the obtained releasable sheet, the abrasion resistance of the adhesive layer was evaluated according to JIS P 8136-1994. Specifically, it is as follows.
Using a Gakushoku Dyeing Friction Fastness Tester (manufactured by Kumagai Riki Kogyo Co., Ltd.) at room temperature (about 25 ° C.), the load of the friction element was set to 500 g, and the obtained removable sheet was set, The test machine was stopped every 10 times of wear (one round of friction and one wear), and the adhesive layer was visually observed. Then, the wear resistance of the adhesive layer was evaluated by confirming the number of times the base material was exposed by the desorption of the adhesive layer as the number of desorption wears. The results are shown in Table 3.

(Evaluation of adhesive strength of pressure sensitive adhesive layer)
The obtained releasable sheet was folded in two so that the adhesive layers were in contact with each other, overlapped with the same paper sheet used for the application of the composition, and this stacked test piece was rolled sealer (Toppan Pressurized with Foam's “Pressle Multi”. The pressurization at this time was performed on a test piece having a width of 100 mm under the condition that the scale of the roll sealer was 34 (340 μm). After pressurizing under this condition, the test piece discharged from the roll sealer was allowed to stand for 30 minutes at a temperature of 23 ° C. and a relative humidity of 50%, and then peel tester (manufactured by Shimadzu Corporation “Autograph AGSH”). )), The resistance value was measured when the releasable sheet was peeled off at a speed of 300 mm / min and a peeling angle of 90 ° (ie, T-shaped peeling). Then, after the measurement was started, the average value was calculated from the measured values of the length of the peeled portion between 40 mm and 140 mm, and the average value was divided by 4 to determine the adhesive force. The results are shown in Table 3.

<Manufacture of removable sheet and evaluation of feed characteristics of removable sheet>
Using the composition for pressure-sensitive adhesive obtained above and a gravure coater, re-peeling was performed in the same manner as above except that the pressure-sensitive adhesive layer was formed with the production scale 1000 times equivalent to the actual scale. An adhesive sheet was produced.
Subsequently, 10,000 sets of the real scale re-peelable sheet thus obtained were passed through an industrial printer (“SX7900” manufactured by Showa Information Equipment Co., Ltd.) with a length of 6 ″ and a width of 13 ″ as one set.
Next, a non-passable releasable sheet similar to that passed through is cut into a length of 36 ″ and a width of 13 ″ to form a removable sheet for evaluation. Attach a spring balance, pull the other end with the scuff flow of the printer, check whether the value indicated by the spring balance is 500 g or more, and if it is 500 g or more, the feed characteristics are good (◯), less than 500 g In this case, it was decided that the feed characteristic was poor (x). The results are shown in Table 3.

[Example 2]
As shown in Table 1, the same as Example 1 except that the amount of PTFE fine particles was changed to 7 parts by mass instead of 4 parts by mass, and the amount of PMMA fine particles was changed to 12 parts by mass instead of 15 parts by mass. A pressure sensitive adhesive composition and a releasable sheet were produced by the method and evaluated. The results are shown in Table 3.

[Example 3]
As shown in Table 1, instead of blending 15 parts by mass of PMMA fine particles, 15 parts by mass of polypropylene (hereinafter, sometimes abbreviated as “PP”) fine particles (“PPW-5” manufactured by Seishin Enterprise Co., Ltd.) A composition for pressure-sensitive adhesive and a releasable sheet were produced and evaluated in the same manner as in Example 1 except that they were blended. The results are shown in Table 3.

[Comparative Example 1]
As shown in Table 1, the same amount as in Example 1 except that the amount of PTFE fine particles was changed to 4 parts by mass to be 12 parts by mass, and the amount of PMMA fine particles was changed to 15 parts by mass to be 8 parts by mass. A pressure sensitive adhesive composition and a releasable sheet were produced by the method and evaluated. The results are shown in Table 3.

[Comparative Example 2]
As shown in Table 1, the composition for pressure-sensitive adhesives was the same as in Example 1 except that the amount of PTFE fine particles was changed to 4 parts by mass and 12 parts by mass, and no PMMA fine particles were added. A releasable sheet was produced and evaluated. The results are shown in Table 3.

[Comparative Example 3]
As shown in Table 1, a pressure-sensitive adhesive composition and a releasable sheet were produced and evaluated in the same manner as in Example 1 except that PTFE fine particles were not blended. The results are shown in Table 3.

[Comparative Example 4]
As shown in Table 1, a pressure-sensitive adhesive composition and a releasable sheet were produced and evaluated in the same manner as in Example 1 except that PMMA fine particles were not blended. The results are shown in Table 3.

  Table 2 shows the measured values of Rockwell hardness and average particle diameter of the fine particles used in the above Examples and Comparative Examples.

In each of Examples 1 to 3 and Comparative Examples 1 to 4, the pressure-sensitive adhesive layer exhibits a good re-peelability equivalent to that of the conventional product and has sufficient adhesive strength as described above. It was.
As is apparent from the above results, in Examples 1 to 3, the pressure-sensitive adhesive layer was excellent in wear resistance, and the removable sheet had good feed characteristics.
On the other hand, in Comparative Example 1, the total blending amount of the fluororesin fine particles and the hard fine particles was almost the same as in Examples 1 to 3, but the blending amount of the fluororesin fine particles was larger than the blending amount of the hard fine particles. Although the wear resistance was excellent, the feed characteristics were poor. In Comparative Example 2, the same result as in Comparative Example 1 was obtained because no hard fine particles were blended. In Comparative Example 3, on the contrary, since the fluororesin fine particles were not blended, the feed characteristics were good, but the wear resistance was poor. In Comparative Example 4, no hard fine particles are blended, whereas the ratio of the amount of the fluororesin fine particles to the blend amount of the adhesive base is smaller than that of Comparative Examples 1 and 2, and the feed characteristics are good. However, the wear resistance was poor.
From the above results, pressure sensitive adhesive can be obtained by using a composition in which both fluororesin fine particles and hard fine particles are blended and the amount of hard fine particles is greater than or equal to the amount of fluororesin fine particles. It was confirmed that the agent layer was excellent in wear resistance without impairing the adhesive strength, and the feed characteristics of the releasable sheet were improved.

  The present invention can be used for a secret information recording sheet, such as a pressure-sensitive pressure-bonding postcard.

  DESCRIPTION OF SYMBOLS 1 ... Tri-fold postcard, 2 ... Base sheet, 3, 3a, 3b ... Folding line, 4 ... Destination information printing, 5 ... Concealment information printing, 6 ... Pressure-sensitive adhesion Agent layer, 11 ... Folded postcard, 21 ... Partially folded postcard

Claims (2)

A releasable sheet in which the overlapping surfaces of the sheets are removably bonded with a pressure-sensitive adhesive layer,
A composition for pressure-sensitive adhesive, wherein the adhesive layer contains an adhesive base, fluororesin microparticles, and hard microparticles made of a material having a larger Rockwell hardness value than the fluororesin. Is formed using,
In the pressure-sensitive adhesive composition, the mass ratio of [the amount of hard fine particles (parts by mass)] / [the amount of the fluororesin fine particles (parts by mass)] is 1.3 or more. Removable sheet.   The removable sheet according to claim 1, wherein the hard fine particles are acrylic resin fine particles.

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