JP6827873B2 - Recording sheet for inkjet - Google Patents

Description

The present invention relates to a recording sheet for an inkjet.

The information recording method using inkjet ink is widely used because it is possible to easily obtain a high-quality image in full color and to realize a high image quality close to that of silver halide photography due to recent technological advances.
The inks are water-based inks containing various coloring materials in a solvent such as water or a mixed solvent of water and a hydrophilic organic solvent, and oil-based inks containing an oil-soluble coloring material in a hydrophobic organic solvent. Ink can be mentioned and used properly according to the purpose.

A recording sheet for an inkjet is configured by providing an ink receiving layer for absorbing ink to form a print or an image on a base material such as paper. The ink receiving layer is required to have good ink drying property and to suppress ink bleeding, which is particularly important when performing high-speed printing. Further, in consideration of mass production, it is desirable that the recording sheet for an inkjet can perform a so-called high-speed super calendar processing in which the surface is smoothed while being heated and pressed at high speed, and the ink receiving layer withstands such processing. It is desirable to be. The ink receiving layer can be formed by applying and drying a composition containing components necessary for fixing ink and a dispersion medium for dispersing them.

On the other hand, the recording sheet for an inkjet may be used in an environment wet with water due to the expansion of applications. In this case, it is desired that the recording sheet for an inkjet device fully exerts its function even in the presence of water. For example, a recording sheet for an inkjet may be used as a removable sheet. As such a removable sheet, for example, an inkjet recording sheet is used as a sheet-like base material, a pressure-sensitive adhesive layer having removability is provided on the surface thereof, and the pressure-sensitive adhesive layer is provided with a pressure-sensitive adhesive layer. Examples thereof include a sheet to be adhered to be re-peelable, a sheet to be adhered to which the sheet to be adhered is not adhered, a recording sheet for inkjet to be folded and adhered to be re-peelable, and the like. In such an inkjet recording sheet, for example, when the ink receiving layer overlaps the adhesive surface, the above sheet or the folded inkjet recording sheet is adhered to the pressure-sensitive adhesive layer, and the ink receiving layer is not exposed. It will be in a sealed state.

Taking a pressure-sensitive crimping postcard as a typical releasable sheet, it may be delivered to the destination in rainy weather, in which case during delivery or in the post-delivery mailbox. Water may adhere. Then, when the postcard in such a state is opened, the ink receiving layer may be broken or peeled off, or the base material may be torn, and the print or the image may not be read. Therefore, it is expected that the recording sheet for an inkjet used as a removable sheet can suppress the occurrence of such a defect.

As a recording sheet for inkjet having improved water resistance, an ink receiving layer containing a pigment, an adhesive, a cationic sizing agent, and two or more kinds of cationic resins having a specific range of cationization degree and molecular weight ( A binder provided with a receiving layer) (see Patent Document 1), containing a pigment and a binder, and the binder contains polyvinyl alcohol having a specific degree of saponification and polyurethane, and the binder is based on the pigment content. A material having an ink receiving layer having an content in a specific range (see Patent Document 2) is disclosed.

Japanese Patent No. 4042970 Japanese Unexamined Patent Publication No. 2016-182818

However, although the inkjet recording sheet disclosed in Patent Document 1 has a high effect of suppressing bleeding due to the adhesion of moisture for printing and images, the water resistance of the ink receiving layer itself is insufficient and the ink receiving layer itself gets wet with water. When used in an environment, there is a problem that the ink receiving layer is likely to be broken or peeled off.
Further, the inkjet recording sheet disclosed in Patent Document 2 also has a high effect of suppressing bleeding due to the adhesion of water on prints and images, and although the ink receiving layer itself has a certain level of water resistance, water There is a problem that the ink receiving layer is liable to be broken or peeled off when it is immersed in the ink or rubbed with water attached.
Further, none of the recording sheets for inkjet disclosed in Patent Documents 1 or 2 can sufficiently exhibit the function as a removable sheet depending on the type of the base material and the type of the pressure-sensitive adhesive layer to be formed. There is also a possibility.

The present invention has been made in view of the above circumstances, and is an ink acceptor having good ink drying property, suppressing ink bleeding, strength enough to withstand high-speed super calendar processing, and water resistance. An object of the present invention is to provide a recording sheet for an inkjet, which has a layer and can be used as a removable sheet even when it is wet with water.

The present invention comprises an inkjet comprising a water resistant substrate, an ink receiving layer formed on at least one surface of the water resistant substrate, and a pressure sensitive adhesive layer formed on the ink receiving layer. In the recording sheet for use, the ink receiving layer contains first and second aggregated light calcium carbonates having different average secondary particle diameters as a pigment, and the ink receiving layer is a cationic styrene type as a binder. The ink receiving layer contains a resin and polyvinyl alcohol, and the ink receiving layer contains a cationic resin other than the cationic styrene resin as an ink fixing agent. In the ink receiving layer, the first and second aggregated light carbon dioxide The ratio of the total content of the cationic styrene resin and the polyvinyl alcohol to the total content of calcium is 11 to 25% by mass, and in the ink receiving layer, the aggregated light calcium carbonates of the first and second aggregates The ratio of the content of the polyvinyl alcohol to the total content is 7% by mass or less, and the pressure-sensitive adhesive layer is one selected from the group consisting of natural rubber-based adhesives and synthetic rubber-based adhesives. Alternatively, the present invention provides a recording sheet for inkjet, which contains two or more kinds of adhesive bases and a filler, and is capable of removably adhering overlapping surfaces of objects to be adhered to each other.

In the recording sheet for inkjet of the present invention, the average secondary particle size of the first aggregated light calcium carbonate is less than 1 μm, and the average secondary particle size of the second aggregated light calcium carbonate is 2 to 5 μm. In the ink receiving layer, the ratio of [content of first aggregated light calcium carbonate (mass)]: [content of second aggregated light calcium carbonate (mass)] is 22:78 to 78:22. It is preferable to have.

According to the present invention, the ink has an ink receiving layer having good drying property, suppression of ink bleeding, strength enough to withstand high-speed super calendar processing, and water resistance, and further gets wet with water. Provided is an inkjet recording sheet that can be used as a removable sheet even in the state of being in the state.

It is sectional drawing which shows typically one Embodiment of the recording sheet for an inkjet of this invention. It is sectional drawing which shows typically the other embodiment of the recording sheet for an inkjet of this invention.

<< Recording Sheet for Inkjet >>
The recording sheet for inkjet of the present invention includes a water-resistant base material, an ink receiving layer formed on at least one surface of the water-resistant base material, and a pressure-sensitive adhesive layer formed on the ink receiving layer. The ink receiving layer contains, as a pigment, first and second aggregated light calcium carbonates having different average secondary particle diameters, and the ink receiving layer serves as a binder. , Cationic styrene resin and polyvinyl alcohol, and the ink receiving layer contains a cationic resin other than the cationic styrene resin as an ink fixing agent, and in the ink receiving layer, the first and first The ratio of the total content of the cationic styrene resin and the polyvinyl alcohol to the total content of the aggregated light calcium carbonate of 2 is 11 to 25% by mass, and in the ink receiving layer, the first and second The ratio of the content of the polyvinyl alcohol to the total content of the aggregated light calcium carbonate is 7% by mass or less, and the pressure-sensitive adhesive layer is composed of a group consisting of a natural rubber-based adhesive and a synthetic rubber-based adhesive. It contains one or more selected adhesive bases and fillers, and can re-detach the overlapping surfaces of the objects to be bonded.

In the recording sheet for an inkjet of the present invention, since the ink receiving layer has the above-mentioned limited composition, the drying property of the ink is good, the ink bleeding can be suppressed, and the ink receiving layer has a high-speed super calendar. By having enough strength to withstand processing and water resistance, printing and images can be stably retained.
That is, the recording sheet for an inkjet of the present invention may be calendar-processed (smoothed).

The calendar process is a process of smoothing the surface of the sheet by pressurizing the surface of the sheet, and the surface of the sheet may be heated at the same time. The high-speed super calendar processing is to perform this calendar processing (smoothing processing) at high speed.
The processing speed at the time of high-speed super calendar processing is, for example, 300 m / min or more.
The recording sheet for an inkjet of the present invention is particularly suitable for mass production because the ink receiving layer can withstand high-speed super calendar processing.

The recording sheet for an inkjet of the present invention further includes a pressure-sensitive adhesive layer and functions as a removable sheet.
In the recording sheet for an inkjet of the present invention, usually, inkjet printing is performed on the surface of the ink receiving layer opposite to the water resistant base material side, and the printing layer is formed in the area on the surface side of the ink receiving layer. Later, a pressure-sensitive adhesive layer is formed on the ink receiving layer. That is, the recording sheet for an inkjet of the present invention corresponds to a so-called post-glue type removable sheet. Therefore, this printing sheet for an inkjet usually includes a printing layer in a region on the surface side of the ink receiving layer. However, the recording sheet for an inkjet of the present invention does not have to include the printing layer.

<Ink receiving layer>
The ink receiving layer can be formed by using a composition for an ink receiving layer containing a component for constituting the ink receiving layer. More specifically, the ink receiving layer can be formed by applying the composition for an ink receiving layer on a water resistant base material and drying it.

The ratio of the contents of the components that do not vaporize at room temperature in the composition for the ink receiving layer is usually the same as the ratio of the contents of the components of the ink receiving layer. In addition, in this specification, "room temperature" means a temperature which is not particularly cooled or heated, that is, a normal temperature, and examples thereof include a temperature of 15 to 25 ° C.

The coating of the composition for the ink receiving layer on the water-resistant substrate may be performed once or may be performed in a plurality of times. When the coating is performed in a plurality of times, the method of further coating the composition for the ink receiving layer on the dried coating layer and the method of further applying the ink receiving on the undried coating layer. It may be any method of coating the layer composition.
The coating amount of the composition for the ink receiving layer may be appropriately adjusted in consideration of the solid content concentration of the composition for the ink receiving layer, the thickness of the ink receiving layer, and the like.

The coating method of the composition for the ink receiving layer is not particularly limited, and any method can be used as long as it can coat a liquid substance. Specific coating methods include, for example, various coaters such as air knife coaters, curtain coaters, die coaters, blade coaters, roll coaters, gate roll coaters, bar coaters, rod coaters, gravure coaters, and gravure offset coaters; wire bars. A known method using a device such as a coater can be mentioned.

The coated composition for the ink receiving layer may be dried by a known method such as blast drying and heating blast drying. Conditions such as drying temperature and drying time may be appropriately set according to the drying method.

The amount of the ink receiving layer formed on the water-resistant substrate is preferably 4 g / m ² or more, more preferably 4.5 g / m ² or more, and particularly preferably 5 g / m ² or more. preferable. When the amount of the ink receiving layer formed is equal to or greater than the lower limit, for example, the effect of suppressing ink bleeding becomes higher, and in particular, at least the surface of the ink receiving layer is calendared (smoothed) using a calendar device. When processed), such an effect becomes higher.
On the other hand, the upper limit of the amount of the ink receiving layer formed on the substrate is not particularly limited, and may be, for example, 30 g / m ² .
The amount of the ink receiving layer formed is preferably within a range set by appropriately combining any of the above lower limit values and upper limit values.

The amount of the ink receiving layer formed can be adjusted by, for example, adjusting the amount of the composition for the ink receiving layer coated on the water resistant substrate, the amount of each compounding component of the composition for the ink receiving layer, and the like. Can be adjusted.

The recording sheet for an inkjet of the present invention may be provided with an ink receiving layer on at least one surface of a water resistant base material, and may be provided on only one side or both sides.
When the recording sheet for an inkjet of the present invention has ink receiving layers on both sides of a water resistant base material, these two ink receiving layers may be the same as each other or may be different from each other.

<Composition for ink receiving layer>
Examples of the composition for the ink receiving layer include the pigment, the binder, the ink fixing agent, and, if necessary, other components that do not fall under any of these.
Hereinafter, each component will be described.

[Pigment]
The pigment is a component that retains the pigment in the ink in the ink receiving layer and affects the absorption and permeation of water.
The composition for the ink receiving layer and the ink receiving layer contain the first aggregated light calcium carbonate and the second aggregated light calcium carbonate having different average secondary particle diameters as the pigment.

Calcium carbonate includes heavy calcium carbonate and light calcium carbonate.
Heavy calcium carbonate is a crushed classification of natural limestone.
Light calcium carbonate is chemically synthesized, and the shape and size of its particles can be chemically controlled. The shape of the particles of light calcium carbonate is usually cubic, spindle-shaped, pillar-shaped, or the like. Light calcium carbonate includes those in which primary particles exist as single particles and those in which primary particles aggregate to form secondary particles.
Light calcium carbonate in which primary particles aggregate to form secondary particles is called aggregated light calcium carbonate. The average particle size of the primary particles (average primary particle size) can be obtained from, for example, observation results with a scanning electron microscope. The average particle size of the secondary particles is determined by, for example, measurement by a laser diffraction method.
In the present invention, as the pigment, first aggregated light calcium carbonate and second aggregated light calcium carbonate having at least different average secondary particle diameters are used.

The average secondary particle size of the first aggregated light calcium carbonate is preferably less than 1 μm, more preferably 0.9 μm or less, for example, 0.8 μm or less, 0.7 μm or less, and 0.6 μm or less. These may be any of the above, but these are examples.
On the other hand, the lower limit of the average secondary particle size of the first aggregated light calcium carbonate is not particularly limited and may be, for example, 0.2 μm.
Since the ink receiving layer contains the first aggregated light calcium carbonate, the effect of suppressing ink bleeding becomes higher when the ink receiving layer is subjected to inkjet printing on an inkjet recording sheet.

The average secondary particle size of the second aggregated light calcium carbonate is preferably 2 to 5 μm, more preferably 2.3 to 4.7 μm, and for example, 2.6 to 4.4 μm. It may be, but this is just an example.
Since the ink receiving layer contains the second aggregated light calcium carbonate, the drying property of the ink becomes higher when the ink is printed on the recording sheet for inkjet. Here, "highly dry ink" means "short time required for drying ink".

The ink receiving layer preferably contains, as the first aggregated light calcium carbonate and the second aggregated light calcium carbonate, any of the above-mentioned average secondary particle diameters in an appropriate combination. For example, a preferred combination of the first aggregated light calcium carbonate and the second aggregated light calcium carbonate in the ink receiving layer is the first having an average secondary particle size of less than 1 μm (for example, 0.2 μm or more and less than 1 μm). Examples include a combination of aggregated light calcium carbonate and a second aggregated light calcium carbonate having an average secondary particle size of 2 to 5 μm, which is an example.
As described above, since the ink receiving layer contains both the first aggregated light calcium carbonate and the second aggregated light calcium carbonate, the recording sheet for an inkjet can be printed in color by a high-speed inkjet printer. The dryness of the ink is improved.

In the composition for the ink receiving layer and the ink receiving layer, the ratio of [content of first aggregated light calcium carbonate (mass)]: [content of second aggregated light calcium carbonate (mass)] is not particularly limited. Is preferably 10:90 to 90:10, more preferably 16:84 to 84:16, and particularly preferably 22:78 to 78:22. The content of the first aggregated light calcium carbonate is preferably high in that the effect of suppressing ink bleeding is higher, and the content of the second aggregated light calcium carbonate is higher in that the ink is more dry. Is preferable. Then, the ratio of [content (mass) of first aggregated light calcium carbonate]: [content (mass) of second aggregated light calcium carbonate] is within the above range, so that the recording sheet for an inkjet can be used. , Both the improvement of the effect of suppressing ink bleeding and the improvement of dryness can be achieved in a more balanced manner, and the recording sheet for inkjet has better dryness of ink even when color printing is performed with a high-speed inkjet printer. It will be good.

The composition for the ink receiving layer and the ink receiving layer do not fall under any of the first aggregated light calcium carbonate and the second aggregated light calcium carbonate, as long as the effects of the present invention are not impaired. It may contain a pigment.
Examples of the other pigment include non-aggregated light calcium carbonate (that is, light calcium carbonate in which primary particles are not aggregated to form secondary particles); the first and first heavy calcium carbonate and the like. Calcium carbonate other than the aggregated light calcium carbonate of 2 can be mentioned.

The first and second aggregated light calcium carbonates and the other pigments may be used alone or in combination of two or more, and when two or more are used in combination, they may be used alone. The combination and ratio of the above may be appropriately selected according to the purpose.

In the composition for the ink receiving layer and the ink receiving layer, the ratio of the total content of the first and second aggregated light calcium carbonate to the total content of the pigment is preferably 92% by mass or more, preferably 94% by mass. The above is more preferable, 96% by mass or more is further preferable, 98% by mass or more is particularly preferable, and 100% by mass may be used.

The ratio of the pigment content (that is, the pigment content of the ink receiving layer) to the total content of the components other than the solvent described later in the composition for the ink receiving layer is preferably 70 to 95% by mass. It is more preferably 74 to 92% by mass, and particularly preferably 78 to 89% by mass. When the ratio is at least the lower limit value, the effect of using the pigment can be obtained more remarkably. Further, when the ratio is not more than the upper limit value, the strength of the ink receiving layer becomes higher.
In the present specification, "pigment content" refers to all pigments used, including not only the first and second aggregated light calcium carbonates but also other pigments, unless otherwise specified. It means the content (that is, the total content of the pigment).

[binder]
The binder is a component for retaining the pigment (first and second aggregated light calcium carbonate, etc.) contained therein in the ink receiving layer.
The composition for the ink receiving layer and the ink receiving layer contain a cationic styrene resin and polyvinyl alcohol as the binder.
The cationic styrene resin is a component that mainly affects the water resistance of the ink receiving layer and also affects the drying property and bleeding of the ink in the ink receiving layer.
Polyvinyl alcohol is a component that mainly affects the strength of the ink receiving layer.

Cationic styrene-based resins have structural units derived from styrene and exhibit cationic properties when dissolved or dispersed in water.
The cationic styrene resin is not particularly limited as long as it is such a resin, and may have, for example, only a structural unit derived from styrene or a derivative thereof, or a configuration derived from styrene or a derivative thereof. It may have a unit and other structural units other than these.
Further, the cationic styrene resin may be a copolymer of a resin having a structural unit derived from styrene or a derivative thereof and another resin other than the resin, and such a copolymer may be used. For example, a copolymer of a resin having a structural unit derived from styrene or a derivative thereof and an acrylic resin (a resin having a (meth) acryloyl group) can be mentioned.

In addition, the description of "derivative" and "class" in this specification means that one or more hydrogen atoms of the original compound are substituted with a group other than a hydrogen atom, unless otherwise specified. Here, the "group" includes not only an atomic group formed by bonding a plurality of atoms but also one atom.
Further, the "(meth) acryloyl group" is a concept including both "acryloyl group" and "methacryloyl group". The same applies to terms similar to the (meth) acryloyl group. For example, "(meth) acrylic acid" is a concept that includes both "acrylic acid" and "methacrylic acid", and "(meth) acrylate". "" Is a concept that includes both "acrylate" and "methacrylate".

The weight average molecular weight of the cationic styrene resin is preferably 5000 to 110,000.
In the present specification, the weight average molecular weight is a polystyrene-equivalent value measured by a gel permeation chromatography (GPC) method unless otherwise specified.

Examples of polyvinyl alcohol include fully saponified polyvinyl alcohol and partially saponified polyvinyl alcohol.

The degree of saponification of polyvinyl alcohol is preferably 90 mol% or more, more preferably 93 mol% or more, and particularly preferably 96 mol% or more. When the degree of saponification of polyvinyl alcohol is at least the above lower limit value, the effect of suppressing ink bleeding in the ink receiving layer becomes higher, and the strength of the ink receiving layer becomes higher. The upper limit of the degree of saponification of polyvinyl alcohol is not particularly limited, and may be, for example, 99.5 mol% or 100 mol%.
The degree of saponification of polyvinyl alcohol is preferably within a range set by appropriately combining any of the above lower limit values and upper limit values.

The degree of polymerization of polyvinyl alcohol is preferably 500 to 2500, more preferably 750 to 2350, further preferably 1000 to 2200, and particularly preferably 1250 to 2000. When the degree of polymerization of polyvinyl alcohol is not more than the above upper limit value, the drying property of the ink becomes higher. Further, when the degree of polymerization of polyvinyl alcohol is at least the above lower limit value, the strength of the ink receiving layer becomes higher.

The composition for the ink receiving layer and the ink receiving layer may contain other binders other than the cationic styrene resin and polyvinyl alcohol as long as the effects of the present invention are not impaired.
Examples of the other binder include cationic styrene resins and water-soluble polymers other than polyvinyl alcohol.

Examples of the water-soluble polymer include modified polyvinyl alcohols such as cation-modified polyvinyl alcohols, anion-modified polyvinyl alcohols, and silanol-modified polyvinyl alcohols; oxidized starch; phosphoric acid esterified starch; locons; casein; carboxymethyl cellulose (CMC); esters. Examples thereof include polyurethanes such as polyurethanes and carbonates.
The polyurethane may be, for example, cationic, anionic or nonionic.

The cationic styrene resin, polyvinyl alcohol, and the other binder may be used alone or in combination of two or more, and when two or more are used in combination, they may be used alone. The combination and ratio may be appropriately selected according to the purpose.

The ratio of the total content of the cationic styrene resin and polyvinyl alcohol to the total content of the binder in the composition for the ink receiving layer and the ink receiving layer is preferably 65% by mass or more, preferably 75% by mass or more. It is more preferable, and it is particularly preferable that it is 85% by mass or more, and for example, it may be either 90% by mass or more, 95% by mass or more, or 100% by mass.

The ratio of the total content of the cationic styrene resin and polyvinyl alcohol to the total content of the first and second aggregated light calcium carbonates in the composition for the ink receiving layer and the ink receiving layer is 11 to 25 mass by mass. %, More preferably 12.5 to 23% by mass, and more preferably 14 to 21% by mass. When the ratio is not more than the lower limit value, the water resistance of the ink receiving layer becomes higher, and when the ratio is not more than the upper limit value, the drying property of the ink in the ink receiving layer becomes higher.

In the composition for the ink receiving layer and the ink receiving layer, the ratio of the content of the polyvinyl alcohol to the total content of the first and second aggregated light calcium carbonate is 7% by mass or less, and is 0.5 to 0.5. It is preferably 7% by mass, more preferably 0.5 to 6.5% by mass, further preferably 0.5 to 6% by mass, and 0.5 to 5.5% by mass. Is particularly preferred. When the ratio is not more than the upper limit value, the water resistance of the ink receiving layer is increased, and when the ratio is not more than the lower limit value, the strength of the ink receiving layer is further increased. In particular, the high strength of the ink receiving layer makes the recording sheet for an inkjet suitable for performing high-speed super calendar processing.

The ratio of the content of the cationic styrene resin to the total content of the first and second aggregated light calcium carbonates in the composition for the ink receiving layer and the ink receiving layer is 4 to 24.5% by mass. It is preferably 6 to 22.5% by mass, more preferably 8 to 20.5% by mass, and particularly preferably 8 to 20.5% by mass.

[Ink fixer]
The ink fixing agent is a component for fixing ink in the ink receiving layer.
In the composition for the ink receiving layer and the ink receiving layer, as the ink fixing agent, a cationic resin other than the cationic styrene resin (in the present specification, it may be referred to as a "cationic resin fixing agent") is used. contains.

The cationic resin fixing agent exhibits cationic properties when dissolved or dispersed in water.
The cationic resin fixing agent is preferably, for example, a monomer, oligomer or polymer of a primary amine, a secondary amine, a tertiary amine or a quaternary ammonium salt, and is preferably the oligomer or polymer. More preferred.

More preferred cationic resin fixers are, for example, alkylamine-epicrolhydrin copolymers; acrylic polymers having a secondary amino group, a tertiary amino group or a quaternary ammonium group; polyvinylamine; polyvinylamidine. 5-membered ring amidines; dicyan cationic resins such as dicyandiamide-formalin copolymers; polyamine-based cationic resins such as dicyandiamide-polyethyleneamine copolymers; polyalkylene polyamines such as polyethylene polyamines and polypropylene polyamines and derivatives thereof. ; diallyldimethylammonium -SO ₂ copolymer; diallylamine salt -SO ₂ copolymer; dimethyldiallylammonium chloride polymer; polymer of allylamine salt, a homopolymer of vinylbenzyl triallyl ammonium salts or copolymers; dialkylamino Ethyl (meth) acrylate quaternary salt copolymer; acrylamide-diallylamine salt copolymer; aluminum salts such as polyaluminum chloride and polyaluminum acetate, and alkylamine-epichlorohydrin copolymer is particularly preferable, and dimethyl Most preferably, it is an amine-epicrolhydrin copolymer.

In the present specification, the polymer also includes a polycondensate.

As the cationic resin fixing agent, 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 composition for the ink receiving layer and the ink receiving layer, the ratio of the content of the cationic resin fixing agent to the content of the pigment is preferably 1 to 40% by mass, and preferably 1 to 25% by mass. More preferably, for example, it may be any one of 1 to 15% by mass, 1 to 10% by mass, 1 to 6% by mass and 1 to 4% by mass, but these are examples.

[Other ingredients]
Examples of the other components in the composition for an ink receiving layer include a solvent, a polyhydric metal salt, a pH adjuster, an antifoaming agent, an antifoaming agent, a mold release agent, a foaming agent, an antioxidant, an antiseptic agent, and water resistance. Examples thereof include components usually used in the ink receiving layer of an inkjet recording sheet, such as an agent, a paper strength enhancer, a coloring dye, a coloring pigment, a dye fixing agent, a pigment dispersant, a fluorescent whitening agent, and an ultraviolet absorber.
As the other components, 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 may be appropriately selected according to the purpose. Good.

(solvent)
In the composition for the ink receiving layer, the solvent other than the pigment, the binder, the ink fixing agent, or the other component other than the solvent is blended as a dispersion or a solution and used as the dispersion medium or the solvent at that time. When not used, the solvent means the dispersion medium used to prepare the dispersion or the solvent used to prepare the solution.
Further, when a solvent is separately blended in addition to the dispersion medium used for preparing the dispersion or the solvent used for preparing the solution, the solvent is the dispersion medium or solvent and this separately blended. Means both solvent and. When all of the pigment, the binder, the ink fixing agent, and the other components other than the solvent are blended as a solid substance, the solvent means a solvent blended separately from these.
Examples of the solvent include water, alcohol and the like.

As the solvent, 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 may be appropriately selected according to the purpose.

The content of the solvent in the composition for the ink receiving layer may be appropriately selected depending on the intended purpose, and is not particularly limited, but is preferably 35 to 90% by mass, for example.

(Multivalent metal salt)
The polyvalent metal salt is a component for improving the drying property of the ink in the ink receiving layer, and is not particularly limited as long as it contains a metal cation having a valence of 2 or more as a constituent component.

Examples of the polyvalent metal salt include calcium chloride (CaCl ₂ ), magnesium chloride (MgCl ₂ ), aluminum chloride (AlCl ₃ ), barium chloride (BaCl ₂ ), zinc chloride (ZnCl ₂ ), and calcium sulfate (CaSO ₄ ). , Magnesium Sulfate (sulfonyl ₄ ), Calcium Nitrate (Ca (NO ₃ ) ₂ ), Magnesium Acetate ((CH ₃ COO) ₂ Mg), Calcium Acetate ((CH ₃ COO) ₂ Ca), Potassium Aluminum Sulfate (Karimyoban, AlK (SO ₄ ) ₂ ) and the like can be mentioned.
The polyvalent metal salt may be a hydrate or a non-hydrate.

Among them, the polyvalent metal salt can improve the drying property and color density of the ink in the ink receiving layer, and the water resistance and scratch resistance of the ink receiving layer in a well-balanced manner, and has high safety. In that respect, calcium chloride, magnesium chloride or potassium aluminum sulfate is preferable, and potassium aluminum sulfate is particularly preferable in that the drying property of the ink becomes higher.

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 may be appropriately selected according to the purpose. Good.

When the composition for the ink receiving layer and the ink receiving layer contain a polyvalent metal salt, it is preferable that the composition contains one or more selected from the group consisting of calcium chloride, magnesium chloride and potassium aluminum sulfate, and potassium aluminum sulfate. Is more preferable, and when potassium aluminum sulfate is contained, one containing either or both of calcium chloride and magnesium chloride is more preferable. By containing at least potassium aluminum sulfate in the ink receiving layer, the drying property of the ink becomes higher.

When the composition for the ink receiving layer and the ink receiving layer contain a polyvalent metal salt, the ratio of the content of the polyvalent metal salt to the content of the pigment in the composition for the ink receiving layer and the ink receiving layer is It is preferably 3 to 55% by mass, more preferably 3 to 25% by mass, further preferably 3 to 15% by mass, and particularly preferably 3 to 10% by mass. When the ratio is at least the lower limit value, the effect of using the polyvalent metal salt can be obtained more remarkably. Further, when the ratio is not more than the upper limit value, excessive use of the polyvalent metal salt is suppressed.

(Defoamer)
The defoaming agent is not particularly limited and may be a known one.
As the defoaming agent, 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 may be appropriately selected according to the purpose. ..

The total content of the other components in the composition for the ink receiving layer may be appropriately adjusted according to the intended purpose.

Examples of particularly preferable compositions for the ink receiving layer and the ink receiving layer are a first aggregated light calcium carbonate having an average secondary particle size of less than 1 μm and a second aggregated light calcium carbonate having an average secondary particle size of 2 to 5 μm. The ratio of [content of first aggregated light calcium carbonate (mass)] to [content of second aggregated light calcium carbonate (mass)] is 22:78 to Those that are 78:22 can be mentioned.

<Manufacturing method of composition for ink receiving layer>
The composition for the ink receiving layer can be produced by blending the pigment, the binder, the ink fixing agent, and other components as necessary, and sufficiently stirring these blending components. In the composition for the ink receiving layer, the pigment is preferably dispersed, and the binder and the ink fixing agent are preferably dissolved or dispersed.

The blending order of each component is not particularly limited.
Further, when blending each component, all the components may be added and then mixed, or some components may be sequentially added and mixed, or all the components may be sequentially added and mixed. You may.
As described above, the solvent may be used by being mixed in advance with the pigment, the binder, the ink fixing agent, or the other components other than the solvent, or may be used alone without being mixed with these components in advance. You may use it.

The temperature at the time of blending each component is not particularly limited and may be appropriately adjusted according to the type of the blended component and the like, but is usually preferably 15 to 30 ° C.
Stirring may be performed by a known method for preparing a dispersion, such as a method using a mixer. The stirring time may be appropriately adjusted according to the total amount of the composition for the ink receiving layer to be produced, the stirring method, and the like, and is preferably 10 minutes to 24 hours, for example.

<Water resistant base material>
The material of the water-resistant base material (sometimes referred to simply as "base material" in the present specification) is not particularly limited as long as it has water resistance, and is selected from those capable of forming a coating layer according to the purpose. do it.
Examples of the water-resistant base material include a base material having a residual ratio of either vertical grain or horizontal grain of 10% or more in a wet tensile strength test based on JIS P8135: 1998.

Specific examples of the material of the water-resistant base material include papers such as water-resistant paper; polyethylene, polypropylene, polyvinyl chloride, polyvinyl chloride, polyvinyl acetate, acrylic resin, AS resin, ABS resin, polyamide, polyacetal, and polyethylene. Examples include terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyphenylene sulfide, polysulfone, polycarbonate, epoxy resin, melamine resin, phenol resin, urea resin, polyurethane, and synthetic resins such as polyimide. Be done.

The thickness of the water-resistant base material is not particularly limited as long as the shape of the water-resistant base material is in the form of a sheet or a film, but is preferably 20 to 1000 μm, more preferably 35 to 500 μm, and 50. It is particularly preferably ~ 200 μm. When the thickness of the water resistant base material is at least the above lower limit value, the structure of the ink receiving layer can be held more stably, and when the thickness of the water resistant base material is at least the above upper limit value, as a recording sheet. The handling of the ink becomes better.

The water resistant base material may be composed of a single layer, may be composed of a plurality of layers of two or more layers, and when 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 water resistant base material is composed of a plurality of layers, the total thickness of each layer may be set to the above-mentioned preferable base material thickness.

As the water resistant base material, a commercially available product may be used, or a product manufactured by a known method may be used.

<Pressure-sensitive adhesive layer>
As described above, the pressure-sensitive adhesive layer is capable of removably adhering the overlapping surfaces of the objects to be bonded to each other. More specifically, the pressure-sensitive adhesive layer adheres the overlapping surfaces of the objects to be bonded to each other and then peels them off to hold the objects to be bonded without damaging the overlapping surfaces of the objects to be bonded. It is possible to make it in a peeled state again.
The pressure-sensitive adhesive layer may be one known in the art.

Examples of the object to be adhered to the recording sheet for an inkjet of the present invention include a recording sheet for an inkjet or a sheet other than that.

When the object to be adhered to the recording sheet for an inkjet of the present invention is a recording sheet for an inkjet, a recording sheet for an inkjet may be separately prepared and adhered (that is, two recordings for an inkjet). (The sheet may be adhered), or the inkjet recording sheet of the present invention may be used alone, and the sheet may be folded and adhered.

The inkjet recording sheet separately adhered to the inkjet recording sheet of the present invention may be the inkjet recording sheet of the present invention, or may be an inkjet recording sheet that does not fall under the one of the present invention.
Further, the inkjet recording sheet to be separately bonded to the pressure-sensitive adhesive layer of the inkjet recording sheet of the present invention may be provided with a pressure-sensitive adhesive layer. In this case, the pressure-sensitive adhesive layer is used as the present invention. It may be attached to the pressure-sensitive adhesive layer of the inkjet recording sheet of the present invention, or a portion other than the pressure-sensitive adhesive layer may be attached to the pressure-sensitive adhesive layer of the inkjet recording sheet of the present invention.

The recording sheet for inkjet of the present invention may be in a state where the object to be adhered is adhered to the pressure-sensitive adhesive layer, or the object to be adhered may not be adhered to the pressure-sensitive adhesive layer. May be folded and bonded by a pressure-sensitive adhesive layer.

The pressure-sensitive adhesive layer can be formed by using a pressure-sensitive adhesive composition containing components for constituting the pressure-sensitive adhesive layer. More specifically, the pressure-sensitive adhesive layer can be formed by applying the pressure-sensitive adhesive composition onto the ink receiving layer and drying it. The pressure-sensitive adhesive layer may be formed not only on the ink receiving layer but also on the water-resistant substrate.

The ratio of the contents of the components that do not vaporize at room temperature in the pressure-sensitive adhesive composition is usually the same as the ratio of the contents of the components in the pressure-sensitive adhesive layer.

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 method of further coating the pressure-sensitive adhesive composition on the dried coating layer and the pressure-sensitive coating layer on the undried coating layer. Any method of applying the adhesive composition may be used.
The coating amount of the pressure-sensitive adhesive composition may be appropriately adjusted in consideration of the solid content concentration of the pressure-sensitive adhesive composition, the thickness of the pressure-sensitive adhesive layer, and the like.

The coating method of the pressure-sensitive adhesive composition is the same as the coating method of the composition for the ink receiving layer described above.
The method for drying the coated pressure-sensitive adhesive composition is the same as the method for drying the composition for the ink receiving layer described above. However, the pressure-sensitive adhesive composition is preferably heat-dried, and the drying temperature may be appropriately adjusted according to the components contained in the pressure-sensitive adhesive composition, but is usually 50 to 150 ° C. Is preferable.

In the inkjet recording sheet, the amount of the formed pressure-sensitive adhesive layer is not particularly limited, is preferably from 1 to 20 g / ^{m 2,} more preferably 1 to 15 g / ^{m 2,} 2 to 10 g It is particularly preferable that it is / m ² . When the amount of the pressure-sensitive adhesive layer formed is equal to or greater than the lower limit, the object to be bonded can be adhered more stably, and when the amount of the pressure-sensitive adhesive layer formed is equal to or less than the upper limit, pressure-sensitive adhesion is achieved. Overformation of the agent layer is suppressed.

The amount of the pressure-sensitive adhesive layer formed can be adjusted, for example, by adjusting the amount of the pressure-sensitive adhesive composition applied, the amount of each compounding component of the pressure-sensitive adhesive composition, and the like.

<Pressure-sensitive adhesive composition>
Examples of the pressure-sensitive adhesive composition include the adhesive base, a filler, and, if necessary, other components that do not fall under any of these.
Hereinafter, each component will be described.

[Adhesive base]
The adhesive base is a component that exhibits adhesive strength and imparts adhesive strength to the pressure-sensitive adhesive layer.
The pressure-sensitive adhesive composition and the pressure-sensitive adhesive layer contain one or more selected from the group consisting of natural rubber-based adhesives and synthetic rubber-based adhesives as the adhesive base.

Examples of the natural rubber-based adhesive and the synthetic rubber-based adhesive include adhesive resins known in the art. For example, examples of synthetic rubber-based adhesives include styrene-butadiene rubber; acrylic copolymers such as (meth) acrylic acid ester copolymers.

As for the natural rubber adhesive and the synthetic rubber adhesive, 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 shall be , It may be appropriately selected according to the purpose.

The ratio of the total content of the natural rubber-based adhesive and the synthetic rubber-based adhesive to the total content of components other than the solvent described later in the pressure-sensitive adhesive composition (that is, the natural rubber-based pressure-sensitive adhesive layer). The total content of the adhesive and the synthetic rubber-based adhesive) is not particularly limited and may be, for example, 50 to 95% by mass, but this is an example.

[Filler]
The filler is a component for reducing the adhesive force of the adhesive, and functions as an adhesive force adjusting agent in the pressure-sensitive adhesive layer.
The pressure-sensitive adhesive layer has removability because it contains such an adhesive base and a filler.

The filler may be either an organic filler or an inorganic filler.
In particular, the filler remains solid without melting even under the heating temperature environment when the pressure-sensitive adhesive composition is heated, such as the drying temperature when the pressure-sensitive adhesive composition is applied and then dried. Those that can exist are preferable, and for example, the melting point of the filler is preferably 45 ° C. or higher.

Preferred organic fillers include, for example, starch.
Preferred examples of the inorganic filler include silica, alumina, glass, zinc oxide, titanium oxide, calcium carbonate, kaolin, active white clay, and shirasu balloon.
The silica may be amorphous silica, and examples of the amorphous silica include synthetic amorphous silica such as dry silica and wet silica.

The filler is preferably in the form of particles (fine particles).
The average particle size of the filler is not particularly limited as long as the effect of the present invention is not impaired, but may be, for example, 1 to 35 μm.
In the present specification, the "average particle diameter" in the present specification was measured by laser diffraction method means the median D ₅₀ of the cumulative volume distribution

As the filler, 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 may be appropriately selected according to the purpose. ..

The ratio of the content of the filler to the total content of the components other than the solvent described later in the pressure-sensitive adhesive composition (that is, the content of the filler in the pressure-sensitive adhesive layer) is not particularly limited. For example, it may be 5 to 50% by mass, but this is an example.

[Other ingredients]
Examples of the other component in the pressure-sensitive adhesive composition include a solvent and the like.
Examples of the solvent in the pressure-sensitive adhesive composition include the same solvent as in the composition for the ink receiving layer.

As the other components, 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 may be appropriately selected according to the purpose. Good.

The total content of the other components in the pressure-sensitive adhesive composition may be appropriately adjusted according to the intended purpose.
However, the ratio of the total content of the other components other than the solvent to the total content of the components other than the solvent in the pressure-sensitive adhesive composition (that is, the other components other than the solvent in the pressure-sensitive adhesive layer). The total content of) is preferably 20% by mass or less, more preferably 10% by mass or less, further preferably 5% by mass or less, for example, 3% by mass or less and 1% by mass or less. It may be either 1 or 0% by mass.
In other words, the ratio of the total content of the adhesive base and the filler to the total content of the components other than the solvent in the pressure-sensitive adhesive composition (that is, the adhesive base of the pressure-sensitive adhesive layer). And the total content of the filler) is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, for example, 97% by mass or more and 99% by mass. It may be any of mass% or more, and may be 100 mass%.

<Manufacturing method of pressure-sensitive adhesive composition>
The pressure-sensitive adhesive composition can be produced by blending the adhesive base, a filler, and if necessary, other components, and sufficiently stirring these blended components.
The pressure-sensitive adhesive composition can be produced by the same method as the above-mentioned composition for an ink receiving layer, except that the compounding components are different.

<< Manufacturing method of recording sheet for inkjet >>
The recording sheet for an inkjet of the present invention can be produced by forming an ink receiving layer on at least one surface of a water resistant base material and forming the pressure-sensitive adhesive layer on the ink receiving layer.
The method for forming the ink receiving layer and the pressure-sensitive adhesive layer is as described above.
When the inkjet recording sheet of the present invention has a printing layer in a region on the surface side of the ink receiving layer opposite to the water resistant substrate side, such an inkjet recording sheet is placed on the water resistant substrate. By forming the ink receiving layer, then forming the printing layer on the ink receiving layer, and then forming the pressure-sensitive adhesive layer on the ink receiving layer (typically, also on the printing layer). , Can be manufactured.

When the recording sheet for an inkjet of the present invention is subjected to calendar processing (smoothing processing), the calendar processing may be performed on at least the surface of the ink receiving layer after the ink receiving layer is formed.

The calendar processing (smoothing processing) of the recording sheet for inkjet (the surface of the ink receiving layer) is known as, for example, a machine calendar, a TG calendar, a super calendar, a soft calendar, a gloss calendar, a compact calendar, a mat super calendar, a mat calendar and the like. It can be done using the calendar device of.

The calendar device may be either an off-type separated from the coater or an on-type integrated with the coater.
Among the calendar devices, the rolls include, for example, a rigid roll and an elastic roll.
Examples of the rigid roll include a metal roll, a roll whose metal surface is mirror-treated with hard chrome plating, and the like.
Examples of the elastic roll include a roll made of a resin such as polyurethane, epoxy resin, polyamide, phenol resin or polyacrylate; and a roll obtained by molding cotton, nylon, asbestos, aramid fiber or the like.

The conditions for the calendar processing are appropriately selected according to the required quality, such as the temperature of the rigid roll, the calendar pressure, the number of nip, the roll speed, and the paper moisture before the calendar processing.

The processing temperature during the calendar processing is not particularly limited, but can be, for example, 10 to 50 ° C.

The pressure during calendar processing is not particularly limited, but can be, for example, 50 to 400 kN / m.
The pressure during calendar processing is adjusted by, for example, adjusting the pressure when pressing a pair of rolls in the calendar device against the recording sheet for inkjet to be processed and the distance between the roll surfaces of the pair of rolls. it can. The method of adjusting the distance between the roll surfaces to adjust the pressure during calendar processing is suitable for calendar processing on a small scale. As an example, the pressure during calendar processing can be easily adjusted by setting the distance between the roll surfaces to preferably 10 to 400 μm according to the thickness of the recording sheet for inkjet to be processed.

Next, the overall configuration of the recording sheet for an inkjet of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing an embodiment of a recording sheet for an inkjet of the present invention. Further, FIG. 2 is a cross-sectional view schematically showing another embodiment of the recording sheet for an inkjet of the present invention.
In FIG. 2, the same components as those shown in FIG. 1 are designated by the same reference numerals as those shown in FIG.
In addition, the drawings used in the following description may be shown by enlarging the main parts for convenience in order to make the features of the present invention easy to understand, and the dimensional ratios and the like of each component are the same as the actual ones. Is not always the case.

The recording sheet 1 for an inkjet shown in FIG. 1 includes an ink receiving layer 12 only on one surface (sometimes referred to as a “first surface” in the present specification) 11a of the water resistant base material 11, and receives ink. The pressure-sensitive adhesive layer 13 is provided on the surface (sometimes referred to as the "first surface" in the present specification) 12a of the layer 12 opposite to the water-resistant base material 11 side.
The inkjet recording sheet 1 further includes a printing layer 14 in a region on the first surface 12a side of the ink receiving layer 12. The print layer 14 is formed by an inkjet printing method, and forms a print, a pattern, an image, or the like.
The recording sheet 1 for an inkjet corresponds to a so-called post-glue type removable sheet, and usually, after inkjet printing is performed on the ink receiving layer 12 to form the printing layer 14, the pressure-sensitive adhesive layer is formed. 13 is formed.

In FIG. 1, reference numeral 12b indicates the surface of the ink receiving layer 12 on the water resistant base material 11 side (sometimes referred to as “second surface” in the present specification).

The recording sheet 2 for inkjet shown in FIG. 2 is on the first surface 11a and the other surface (sometimes referred to as “second surface” in the present specification) 11b (that is, on both sides) of the water resistant base material 11. Both are provided with an ink receiving layer 12, and a pressure-sensitive adhesive layer 13 is provided on the first surface 12a of these ink receiving layers 12.

Regarding the two ink receiving layers 12 and 12 in the recording sheet 2 for inkjet, those provided on the first surface 11a of the water resistant base material 11 are shown as the first ink receiving layer 121, if necessary. What is provided on the second surface 11b of the water resistant base material 11 is shown as a second ink receiving layer 122 to distinguish them from each other.
Similarly, with respect to the two pressure-sensitive adhesive layers 13 and 13 in the recording sheet 2 for inkjet, those provided on the first surface 11a side of the water-resistant base material 11 are used as the first pressure-sensitive adhesive layer 13 and 13 as needed. What is shown as the adhesive layer 131 and provided on the second surface 11b side of the water resistant base material 11 is shown as the second pressure-sensitive adhesive layer 132 to distinguish them from each other.

The inkjet recording sheet 2 further includes a region (in other words, a surface (first surface) 121a of the first ink receiving layer 121 opposite to the water resistant base material 11 side of the first surface 11a side of the ink receiving layer 12. On the side region and the surface (first surface) 122a side of the second ink receiving layer 122 opposite to the water resistant base material 11 side), the printing layer 14 similar to that of the recording sheet 1 for inkjet is used. Is equipped with.
Like the inkjet recording sheet 1, the inkjet recording sheet 2 also corresponds to a so-called post-glue type removable sheet, and usually, the ink receiving layer 12 is subjected to inkjet printing to form the printing layer 14. After that, the pressure-sensitive adhesive layer 13 is formed.

In FIG. 2, reference numerals 121b and 122b indicate the surfaces (second surface) of the first ink receiving layer 121 and the second ink receiving layer 122 on the water resistant base material 11 side, respectively.

In FIGS. 1 and 2, the water resistant base material 11, the ink receiving layer 12 (first ink receiving layer 121, the second ink receiving layer 122) and the pressure sensitive adhesive layer 13 (first pressure sensitive adhesive layer 131, first The two pressure-sensitive adhesive layers 132) have been described above.

1 and 2 show a recording sheet for inkjet in which the object to be adhered is not adhered to the pressure-sensitive adhesive layer, but the object to be adhered is adhered to the pressure-sensitive adhesive layer. These single ink-ink recording sheets may be folded and adhered by a pressure-sensitive adhesive layer.

The inkjet recording sheet shown in FIGS. 1 and 2 is only an example of the present invention, and the inkjet recording sheet of the present invention is not limited thereto.

For example, in the recording sheet for an inkjet of the present invention, the ink receiving layer may be provided on the entire surface of the surface to be formed of the water resistant base material, or may be provided only in a part of the region.
The pressure-sensitive adhesive layer may be provided on the entire surface of the ink receiving layer, or may be provided only in a part of the region. Further, when the ink receiving layer is provided only in a part of the formation target surface of the water resistant base material (in other words, the formation target surface of the water resistant base material is not covered by the ink receiving layer). If there is), the pressure sensitive adhesive layer may be provided in direct contact with the water resistant substrate.
Similar to the pressure-sensitive adhesive layer, the printing layer may be provided on the entire surface of the first surface of the ink receiving layer, or may be provided only in a part of the region.

When the recording sheet for an inkjet of the present invention is viewed in a plan view from above the side where the ink receiving layer is provided, the surface area of the ink receiving layer may be equal to or less than the surface area of the water resistant substrate. , As long as this condition is satisfied, there is no particular limitation.
Similarly, when the recording sheet for an inkjet of the present invention is viewed in a plan view from above the side where the pressure-sensitive adhesive layer is provided, the surface area of the pressure-sensitive adhesive layer is relative to the surface area of the water-resistant base material. It does not have to be the same or less, and is not particularly limited as long as this condition is satisfied.
The shapes of the pressure-sensitive adhesive layer, the ink receiving layer, and the water-resistant base material when viewed in a plan view as described above can be arbitrarily set according to the purpose and are not particularly limited.

The recording sheet for an inkjet of the present invention may be provided with a layer other than the ink receiving layer, the pressure-sensitive adhesive layer and the printing layer on the water-resistant substrate, depending on the purpose.
Examples of the other layer include an adhesive layer, an adhesive layer, a release film, and the like.
In addition, in this specification, the description of a simple "adhesive layer" means an adhesive layer other than the pressure-sensitive adhesive layer (that is, a non-pressure-sensitive adhesive layer) unless otherwise specified. To do.

Examples of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive layer include those for attaching and fixing an inkjet recording sheet to an object. When the recording sheet for an inkjet is provided with such an adhesive layer or an adhesive layer, it is preferable that a release film is further provided on these layers and the adhesive layer or the adhesive layer is not exposed.
Further, the recording sheet for an inkjet has a release film on the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer does not have to be exposed.

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.

<Base material>
In the following examples and comparative examples, the following materials were used as the base material.

<Raw materials>
In the following Examples and Comparative Examples, the pigments and binders shown below were used.

In the following examples and comparative examples, the following raw materials were used as raw materials other than pigments and binders.
[Cationic resin fixing agent]
(C) -1: Alkylamine-epichlorohydrin polycondensate (“Jetfix 260” manufactured by Satoda Kako Co., Ltd.)

<Pressure-sensitive adhesive composition>
In the following Examples and Comparative Examples, the pressure-sensitive adhesive compositions shown below were used.

<< Manufacturing of Recording Sheets for Inkjet >>
[Example 1]
Pigment (a) -1 (25 parts by mass) and pigment (a) -2 (75 parts by mass), binder (b) -1 (12.5 parts by mass (solid content)), binder (b) -2 ( 2.5 parts by mass (solid content)) and the cationic resin fixing agent (c) -1 (2.78 parts by mass (solid content)) are added, and these components are sufficiently stirred at room temperature to remove these components. The mixture was dispersed to obtain a composition for an ink receiving layer, which is a dispersion liquid.
Next, using a wire bar coater, the composition for the ink receiving layer obtained above is coated on the base material (z) -1 with a coating amount such that the amount of the ink receiving layer formed is 9 g / m ^2. Then, it was dried at 105 ° C. to form an ink receiving layer having a thickness of about 10 μm to obtain a laminated sheet.
The obtained laminated sheet was further subjected to calendar processing at room temperature. At the time of calendar processing, the distance between the roll surfaces of the pair of metal rolls was set to 25 μm, and the laminated sheets were passed between the roll surfaces to pressurize the laminated sheets.

Next, on the surface of the ink receiving layer in the laminated sheet after the calendar processing, a pressure-sensitive adhesive layer is formed in a region that becomes a laminated surface when the laminated sheet is folded in order to be a recording sheet for an inkjet. The pressure-sensitive adhesive composition (y) -1 was coated with a coating amount of 3 to 5 g / m ² . One hour after coating, the laminated sheet was folded and crimped under the condition that the peel strength after crimping was 2N / 6 inches (15.24 cm) to obtain a recording sheet for an inkjet. In the obtained recording sheet for an inkjet, the formed pressure-sensitive adhesive layers are bonded to each other, and the overlapped surfaces are releasably bonded to each other via the pressure-sensitive adhesive layers. is there.

[Examples 2 to 7 , Comparative Examples 1 to 11 ]
Table 5 shows one or more of the type of the base material, the type and amount of the compounding components of the composition for the ink receiving layer, the amount of the ink receiving layer formed, and the type of the pressure-sensitive adhesive composition. A recording sheet for an inkjet was produced in the same manner as in Example 1 except for the points.
In addition, the description of "-" in the column of the compounding component in Table 5 means that the component is not compounded.

<< Evaluation of Recording Sheet for Inkjet >>
The following items were evaluated with respect to the above-mentioned inkjet recording sheet or the laminated sheet after calendar processing (hereinafter, may be simply referred to as "laminated sheet") before being used as an inkjet recording sheet. The results are shown in Table 6 .

[Dot bleeding]
Dot bleeding was evaluated by the dot shape coefficient. The evaluation sample is printed with a desktop inkjet printer on the ink receiving layer of the laminated sheet after calendar processing at a size of 2 cm × 2 cm and a density of 10% so that dots do not overlap (single color printing). ). Next, a microscope image of the surface of the laminated sheet was taken and analyzed using a dot analyzer (“DA6000” manufactured by Oji Measuring Instruments Co., Ltd.). Specifically, the peripheral length and area of the dots were measured, and the dot shape coefficient was calculated by the following formula.
Dot shape coefficient = (peripheral length) ² / (4π x area)

The dot shape coefficient becomes 1 when the dots are perfect circles, and becomes a larger value as the shape of the dots deviates from the perfect circle, that is, the dots are blurred. The dot shape coefficient measured by a desktop inkjet printer (printing speed 250 f (76.2 m) / min) has a sufficient correlation with the dot shape coefficient measured by a high-speed inkjet printer (printing speed 500 f (152.4 m) / min). I confirmed in advance that there is.

By the above method, the dot shape coefficient was calculated for about 30 dots to obtain the average value, and the dot bleeding was evaluated according to the following evaluation criteria. The results are shown in Table 6. The numerical value in parentheses in the column of "dot bleeding" in Table 6 is the average value of the dot shape coefficients.
(Evaluation criteria)
A: The average value of the dot shape coefficients is 1.8 or less, and the bleeding of dots is completely or highly suppressed.
B: The average value of the dot shape coefficients exceeds 1.8 and is 2.0 or less, and dot bleeding is suppressed.
C: The average value of the dot shape coefficients exceeds 2.0, and dot bleeding is not suppressed.

[Ink drying property]
Using an inkjet printer, printing was performed on the ink receiving layer of the laminated sheet after the calendar processing with four color inks of cyan, magenta, yellow, and black. More specifically, the printing was performed by changing the printing density for each color from 100% to 400% in units of 10%.
Then, immediately after the completion of printing, a transparent polyethylene terephthalate film (thickness 100 μm) was superposed on the printed surface of the laminated sheet and firmly pressed against the printed surface to bring them into close contact with each other.
Next, with the film in close contact with the printing surface, visually observing from the side opposite to the contact surface with the printing surface, the maximum print density of the ink not transferred from the printing surface to the contact surface is confirmed. Then, the dryness of the ink was evaluated according to the following evaluation criteria. The results are shown in Table 6. The numerical value in parentheses in the column of "ink dryness" in Table 6 is the maximum print density. In this evaluation method, it was confirmed in advance that the evaluation results would not vary as long as the film was in close contact with the printed surface.
(Evaluation criteria)
A: The maximum print density of the ink is 300% or more, the drying property is excellent, and the ink has high-speed printing suitability.
B: The maximum print density of the ink is 190% or more and less than 300%, the drying property is good, and the ink has high-speed printing suitability.
C: The maximum print density of the ink is less than 190%, the drying property is inferior, and the ink does not have high-speed printing suitability.

The reason why the dot bleeding and the dryness of the ink were evaluated on the laminated sheet after the calendar processing was that the target of the inkjet printing was not the pressure-sensitive adhesive layer formed on the ink receiving layer but the ink receiving layer. This is because.

[Strength of ink receiving layer]
The laminated sheet after the calendar treatment was cut into a size of 70 mm × 40 mm to prepare a test piece. Further, a polyethylene terephthalate (PET) film having a size of 20 mm × 40 mm and a thickness of 75 μm was prepared. The test piece and the PET film are laminated so that the entire surface of one surface of the PET film overlaps one surface of the test piece and the surface of the test piece on the side provided with the ink receiving layer is an exposed surface. The first laminate was obtained. Further, the first laminate was sandwiched between two stainless steel mirror plates having a size larger than that of the first laminate and a thickness of 1 mm to form a second laminate. At this time, the first laminated product was arranged so that the entire surfaces of both of the first laminated products overlap with the mirror surface plate. As a result, in the second laminate, the ink receiving layer of the test piece is in direct contact with the mirror plate. Next, using a heat pressurizing device (laminator) capable of pressurizing and heating at the same time, the second laminate is sandwiched between the two heat and pressurizing treatment surfaces, and the temperature is 50 ° C. and the pressure is 10 kN. The second laminate was heat-pressurized under the condition of a treatment time of 30 seconds. At this time, the second laminate was arranged so that the entire surfaces of both surfaces of the second laminate overlap with the heat-pressurized surface. As a result, the pressure during the heat and pressurization treatment was evenly applied to the entire surface of the test piece that overlaps with the PET film.
After the completion of the heat and pressurization treatment, the surface of the mirror plate that was in direct contact with the test piece was visually observed, and the presence or absence of transfer of the ink receiving layer to the mirror plate, and if there was transfer, the degree of transfer. From the viewpoint, the strength of the ink receiving layer was evaluated according to the following evaluation criteria. The results are shown in Table 6.
(Evaluation criteria)
A: No transfer of the ink receiving layer to the mirror plate is observed, and the ink receiving layer has sufficient strength to withstand high-speed super calendar processing.
B: Although some transfer of the ink receiving layer to the mirror surface plate is observed, the ink receiving layer has enough strength to withstand high-speed super calendar processing.
C: The transfer of the ink receiving layer to the mirror plate is clearly observed, and the ink receiving layer is not strong enough to withstand the high-speed super calendar processing.

[Water resistance of ink receiving layer]
Using the same desktop inkjet printer used in the evaluation of dot bleeding described above, printing (solid printing) at 100% density with black ink was performed on the entire surface of the ink receiving layer of the laminated sheet after calendar processing. It was. Then, the ink after printing was completely dried.
Next, the printed laminated sheet was immersed in a sufficient amount of tap water for 1 minute, and the ink receiving layer was rubbed with a finger in the tap water in that state. Next, the state of the ink receiving layer was visually observed, and the water resistance of the ink receiving layer was evaluated according to the following evaluation criteria from the viewpoint of the presence or absence of breakage and peeling of the ink receiving layer and the degree of breakage or peeling. The results are shown in Table 6. The reason why the laminated sheet was printed with black ink as described above is that the presence or absence of breakage and peeling of the ink receiving layer can be clearly visually recognized.
In addition, in this specification, in order to distinguish "water resistance of an ink receiving layer" of this item from "water resistance of an ink receiving layer at the time of wet opening" which will be described later, "ink at the time of non-wetting opening". It may be referred to as "water resistance of the receiving layer".
(Evaluation criteria)
A: No breakage or peeling of the ink receiving layer was observed, and the ink receiving layer has excellent water resistance.
B: The ink receiving layer is slightly broken or peeled off, but there is no problem in actual use, and the ink receiving layer has good water resistance.
C: The ink receiving layer is clearly broken or peeled off, there is a problem in actual use, and the ink receiving layer is inferior in water resistance.

[Openability]
Evaluation of the above-mentioned dot bleeding on one surface of the ink receiving layer in the laminated sheet after the calendar processing, which becomes the overlapping surface when the laminated sheet is folded in order to be a recording sheet for an inkjet. Using the same desktop inkjet printer used at that time, printing (solid printing) was performed with black ink at a density of 100%. Then, the ink after printing was completely dried.
Next, both sides of the surface of the ink receiving layer in the laminated sheet after printing, which are the overlapping surfaces (in other words, both the printed surface and the non-printed surface of the ink receiving layer). The pressure-sensitive adhesive composition (y) -1, (y) -2, or (y) -3 is applied to the pressure-sensitive adhesive layer with a coating amount of 3 to 5 g / m ^2. I worked on it. One hour after coating, the laminated sheet was folded and crimped under the condition that the peel strength after crimping was 2N / 6 inches (15.24 cm) to obtain a recording sheet for an inkjet. In the obtained recording sheet for an inkjet, the formed pressure-sensitive adhesive layers are bonded to each other, and the overlapped surfaces are releasably bonded to each other via the pressure-sensitive adhesive layers. is there.

Two hours after the overlapped surfaces were bonded to each other (after the inkjet recording sheet was manufactured), an attempt was made to open the inkjet recording sheet in a normal state (an attempt was made to re-peel it). Next, if the package can be opened, the state of the base material and the ink receiving layer of the recording sheet for inkjet after opening is visually observed, and the viewpoint of whether or not the base material is torn and whether or not the ink receiving layer is broken or peeled off. Therefore, if the base material is torn or the ink receiving layer is broken or peeled off, the openability of the recording sheet for an inkjet is evaluated according to the following evaluation criteria from the viewpoint of the degree of tearing. The results are shown in Table 6. As described above, the reason why the black ink is used for printing on the recording sheet for an inkjet is to make it possible to clearly see whether or not the ink receiving layer is broken or peeled off. Further, in the following, the description of mere "opening property" means the above-mentioned "opening property of a recording sheet for an inkjet in a normal state (not at the time of wet opening described later)" unless otherwise specified. ..
(Evaluation criteria)
A: The overlapping surfaces of the recording sheets for inkjet can be peeled off again, the ink receiving layer is not broken or peeled off, the base material is not torn, and the opening property is excellent.
B: The overlapping surfaces of the recording sheets for inkjet can be peeled off again, and the ink receiving layer is slightly broken or peeled off, or the base material is slightly torn, but there is no problem in actual use and the opening property is open. Is good.
C: The overlapping surfaces of the recording sheets for inkjet cannot be re-peeled, or the re-peeling is possible, but the ink receiving layer is largely broken or peeled off, or the base material is severely torn. It is recognized, there is a problem in actual use, and it is inferior in openability.

[Water resistance of the base material when it is wet and opened]
At the time of the above evaluation of "openability", the water resistance of the base material at the time of wet opening was separately evaluated for the recording sheet for an inkjet whose evaluation result was A or B by the following procedure.
That is, a recording sheet for an inkjet was obtained by the same method as in the evaluation of "openability" described above.
Next, the obtained recording sheet for inkjet was immersed in a sufficient amount of tap water for 2 hours, then pulled out from the tap water, excess water was removed using a dry towel, and an attempt was made to open the package immediately (removal). I tried to make it). Next, the state of the base material of the recording sheet for inkjet is visually observed, and from the viewpoint of the presence or absence of tearing of the base material and the degree of tearing, the water resistance of the base material at the time of wet opening is based on the following evaluation criteria. Gender was evaluated. As described above, since the printing was performed on the recording sheet for the inkjet with black ink, the presence or absence of tearing of the base material can be clearly visually recognized. The results are shown in Table 6.
(Evaluation criteria)
A: No tearing of the base material was observed, and the base material has excellent water resistance.
B: Although some tearing of the base material is observed, there is no problem in actual use, and the base material has good water resistance.
C: The base material is clearly torn, there is a problem in actual use, and the base material is inferior in water resistance.

[Water resistance of ink receiving layer when wet and opened]
At the time of the evaluation of the above-mentioned "water resistance of the base material at the time of wet opening", the state of the ink receiving layer at the time of wet opening was visually observed for the recording sheet for an inkjet whose evaluation result was A or B. Then, from the viewpoint of the presence or absence of breakage and peeling of the ink receiving layer, and the degree of breakage or peeling, the water resistance of the ink receiving layer at the time of wet opening was evaluated according to the following evaluation criteria. At the time of this evaluation, the overlapping surfaces of the ink receiving layers are bonded to each other via the pressure-sensitive adhesive layer. Therefore, if the ink receiving layers are broken or peeled off on the re-peeled overlapping surfaces, the overlapping surfaces are formed. Transfer of the ink receiving layer from one surface to the other may be observed. Further, as described above, since the printing is performed on the recording sheet for the inkjet with black ink, the presence or absence of breakage and peeling of the ink receiving layer can be clearly visually recognized. The results are shown in Table 6.
(Evaluation criteria)
A: No breakage or peeling of the ink receiving layer was observed, and the ink receiving layer has excellent water resistance.
B: The ink receiving layer is slightly broken or peeled off, but there is no problem in actual use, and the ink receiving layer has good water resistance.
C: The ink receiving layer is clearly broken or peeled off, there is a problem in actual use, and the ink receiving layer is inferior in water resistance.

The description of "-" in the evaluation result column of Table 6 means that the item was not evaluated.

As is clear from the above results, the inkjet recording sheets of Examples 1 to 7 had a good effect of suppressing dot bleeding and good ink drying properties, and had good characteristics as an inkjet recording sheet. All of these inkjet recording sheets have the strength of the ink receiving layer, the water resistance of the ink receiving layer at the time of non-wet opening and wet opening, the water resistance of the base material at the time of wet opening, and the opening of the inkjet recording sheet. The sex was all good.

On the other hand, in the recording sheet for an inkjet of Comparative Example 1, the strength of the ink receiving layer was insufficient because polyvinyl alcohol was not used as a binder.
The inkjet recording sheets of Comparative Examples 2 to 4 were inferior in openability of the inkjet recording sheets due to the use of the pressure-sensitive adhesive composition (y) -2.
The recording sheet for an inkjet of Comparative Example 5 was inferior in the openability of the recording sheet for an inkjet because the pressure-sensitive adhesive composition (y) -3 was used.

In the recording sheet for inkjet of Comparative Example 6, the ratio of the total content of the cationic styrene resin and the polyvinyl alcohol to 100 parts by mass of the total content of the first and second aggregated light calcium carbonate was too low. The water resistance of the ink receiving layer at the time of non-wetting opening was insufficient.
The inkjet recording sheet of Comparative Example 7 received ink when it was not wet and opened because the ratio of the content of polyvinyl alcohol to 100 parts by mass of the total content of the first and second aggregated light calcium carbonate was too high. The water resistance of the layer was insufficient.
In the recording sheet for inkjet of Comparative Example 8, dot bleeding was suppressed because the ratio of the content of polyvinyl alcohol to 100 parts by mass of the total content of the first and second aggregated light calcium carbonate was too high. However, the water resistance of the ink receiving layer at the time of non-wetting opening was insufficient.

Since the base material (z) -2 was used in the recording sheets for inkjet of Comparative Examples 9 to 11, the water resistance of the base material at the time of wet opening was insufficient, and the base material was largely torn.
Further, the inkjet recording sheet of Comparative Example 10 did not use a cationic resin other than the cationic styrene resin as the ink fixing agent, so that dot bleeding was not suppressed.
Further, the recording sheet for an inkjet of Comparative Example 11 does not use a cationic styrene resin as a binder, and the ratio of the content of polyvinyl alcohol to the total content of 100 parts by mass of the first and second aggregated light calcium carbonates is Because it was too high, the water resistance of the ink receiving layer at the time of non-wetting opening was insufficient.

INDUSTRIAL APPLICABILITY The present invention can be used as a recording sheet for an inkjet, which has excellent suitability for inkjet printing and is intended to be a removable sheet for performing high-speed super calendar processing.

1, 2, ... Ink recording sheet, 11 ... Water resistant base material, 11a ... First surface of water resistant base material, 11b ... Second surface of water resistant base material, 12 ... Ink receiving layer, 12a ... 1st surface of ink receiving layer, 12b ... 2nd surface of ink receiving layer, 121 ... 1st ink receiving layer, 121a ... 1st surface of 1st ink receiving layer Surfaces, 121b ... Second surface of the first ink receiving layer, 122 ... Second ink receiving layer, 122a ... First surface of the second ink receiving layer, 122b ... Second ink receiving layer Second surface, 13 ... pressure-sensitive adhesive layer, 131 ... first pressure-sensitive adhesive layer, 132 ... second pressure-sensitive adhesive layer, 14 ... printing layer

Claims (1)

A water-resistant base material, an ink receiving layer formed on at least one surface of the water-resistant base material, and a region on the surface side of the ink receiving layer opposite to the water-resistant base material side. and inkjet printing layer, and the water resistant substrate side of the ink receiving layer a record sheet and a pressure-sensitive adhesive layer formed on the surface opposite,
The ink receiving layer contains first and second aggregated light calcium carbonates having different average secondary particle diameters as pigments.
The ink receiving layer contains a cationic styrene resin and polyvinyl alcohol as a binder, and contains
The ink receiving layer contains a cationic resin other than the cationic styrene resin as an ink fixing agent.
In the ink receiving layer, the ratio of the total content of the cationic styrene resin and polyvinyl alcohol to the total content of the first and second aggregated light calcium carbonate is 11 to 25% by mass.
In the ink receiving layer, the ratio of the content of polyvinyl alcohol to the total content of the first and second aggregated light calcium carbonate is 7% by mass or less.
The average secondary particle size of the first aggregated light calcium carbonate is less than 1 μm, and the average secondary particle size of the second aggregated light calcium carbonate is 2 to 5 μm.
In the ink receiving layer, the ratio of [content (mass) of first aggregated light calcium carbonate]: [content (mass) of second aggregated light calcium carbonate] is 22:78 to 78:22. ,
The pressure-sensitive adhesive layer contains one or more adhesive bases selected from the group consisting of natural rubber-based adhesives and synthetic rubber-based adhesives, and fillers, and stacks the objects to be bonded. is combined faces capable adhesion repeelably, the record sheet.

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