JP2019043097A - Recording sheet for inkjet - Google Patents

Abstract

To provide a recording sheet for inkjet capable of achieving good dryness of ink and surface glossiness even if having only one ink receiving layer on a substrate.SOLUTION: There is provided a recording sheet for inkjet 1 which comprises a substrate 11 and an ink receiving layer 12 formed on at least one surface 11a of the substrate 11, wherein the ink receiving layer 12 contains first and second aggregated light calcium carbonates having different average secondary particle diameters as a pigment and a polyvinyl alcohol having a saponification degree of 97 mol% or more as a binder and contains hollow particles, and in the ink receiving layer 12, the ratio of the content of the polyvinyl alcohol to the total content of the first and second aggregated light calcium carbonates is set to be 4 to 13.5 mass% and the ratio of the content of the hollow particles to the total content of the first and second aggregated light calcium carbonates is set to be 3 to 23 mass%.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an inkjet recording sheet.

An information recording method using an ink jet ink is widely used because a full color high quality image can be easily obtained and the recent high technology can realize high image quality approaching silver salt photography.
As the ink, an aqueous ink containing various coloring materials in a solvent such as water or a mixed solvent of water and a hydrophilic organic solvent, and an oil-based ink containing an oil-soluble coloring material in a hydrophobic organic solvent Inks and the like can be mentioned, and these inks can be used properly depending on the purpose.

The inkjet recording sheet is configured to have an ink receiving layer for absorbing ink and forming a print or an image on a substrate such as paper. The ink receiving layer can be formed by coating and drying a composition containing components necessary for fixing the ink and the like and a dispersion medium for dispersing these.
The ink receptive layer is required to have a good ink drying property, and also to have other properties depending on the application. For example, ink jet recording sheets having good ink drying properties and surface glossiness are widely used for various purposes, and they are highly versatile and important.

  As such an inkjet recording sheet having surface glossiness, an inkjet recording sheet having a glossiness of 45 or more measured under an incident angle of 60 ° and an ink drying time of 20 minutes or less Material (refer to Patent Document 1), an under layer, an ink receiving layer, and a gloss layer containing a pigment and an adhesive as main components are sequentially laminated on a paper substrate, and the pigment of the under layer is mainly calcined kaolin. And the pigment of the porous layer of the ink receiving layer has an oil absorption of 2 to 5 times that of calcined kaolin as the main component, and the pigment of the glossing layer has an average particle diameter of 500 nm or less An ink jet recording material (see Patent Document 2) containing ultrafine particles as a main component and having the above glossing layer formed by a cast processing method, and having at least two or more layers on a support An ink jet recording medium containing the fine particles and the water-soluble resin as the main components among the layers, and hollow particles having a porosity of 30% or more as the main components in the lowermost layer provided on the side close to the support (patent Reference 3) is disclosed.

JP 2000-335097 A JP 2005-280149 A Unexamined-Japanese-Patent No. 2006-103040

  However, each of the ink jet recording sheets disclosed in Patent Documents 1 to 3 includes two or more layers including a layer corresponding to an ink receiving layer on a substrate (support). ing. This is because it is necessary to increase the smoothness of the surface of the sheet in order to make the surface of the recording sheet for ink jet recording have a high glossiness. It is because the drying property of the ink of the said sheet will deteriorate. As described above, in the ink jet recording sheet, the surface glossiness and the drying property of the ink are generally opposite properties, and a layer having both of these properties is realized by a single ink receiving layer. It is technically very difficult. Therefore, in the ink jet recording sheet disclosed in Patent Documents 1 to 3, by providing two or more layers including the ink receiving layer on the substrate, good ink drying property and surface glossiness are obtained. , To achieve both.

  However, the recording sheet for inkjet provided with such two or more layers on the base material has a problem that the production efficiency is low because the number of processes required at the time of its production increases by the number of layers. There was a point.

  Therefore, an object of the present invention is to provide an ink jet recording sheet capable of achieving good ink drying property and surface glossiness even if only one ink receiving layer is provided on a substrate.

  The present invention is an ink jet recording sheet comprising a substrate and an ink receiving layer formed on at least one surface of the substrate, wherein the ink receiving layer comprises, as a pigment, an average secondary particle. The ink receiving layer contains, as a binder, polyvinyl alcohol having a degree of saponification of 97 mol% or more, and the ink receiving layer contains hollow particles, and the first and second aggregated light calcium carbonates have different diameters. In 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 carbonates is 4 to 13.5% by mass, the ink receiving layer In the layer, the ratio of the content of the hollow particles to the total content of the first and second aggregated light calcium carbonates is 3 to 23% by mass. To provide a use recording sheets.

  In the ink jet recording sheet of the present invention, the average secondary particle diameter of the first aggregated light calcium carbonate is less than 1 μm, and the average secondary particle diameter of the second aggregated light calcium carbonate is 2 to 5 μm. And in the ink receiving layer, a ratio of [the first content of aggregated light calcium carbonate (mass)]: [the content of the second aggregated light calcium carbonate (mass)] is 22:78 to 78:22. Is preferred.

  According to the present invention, it is possible to provide an inkjet recording sheet capable of achieving good ink drying properties and surface gloss even when only one ink receiving layer is provided on a substrate.

FIG. 1 is a cross-sectional view schematically showing an embodiment of an inkjet recording sheet of the present invention. FIG. 6 is a cross-sectional view schematically showing another embodiment of the inkjet recording sheet of the present invention.

<< Inkjet recording sheet >>
The inkjet recording sheet of the present invention is an inkjet recording sheet comprising a substrate and an ink receiving layer formed on at least one surface of the substrate, wherein the ink receiving layer is a pigment. An ink receiving layer containing polyvinyl alcohol having a saponification degree of 97 mol% or more as a binder, the ink receiving layer containing first and second aggregated light calcium carbonates having different average secondary particle sizes; The layer contains hollow particles, and the ratio of the content of the polyvinyl alcohol to the total content of the first and second aggregated light calcium carbonates in the ink receiving layer is 4 to 13.5% by mass. In the ink receiving layer, the ratio of the content of the hollow particles to the total content of the first and second aggregated light calcium carbonates is 3 to 2 And it has a mass%.

The ink jet recording sheet according to the present invention has good ink drying property and surface gloss even if only one ink receiving layer is provided on the substrate by the ink receiving layer having the above-described limited composition. Can be realized.
In addition, since the ink jet recording sheet of the present invention can include only one ink receiving layer as described above, the number of layers can be small, the number of steps can be small, and the production efficiency is high.

  The ink jet recording sheet of the present invention can be used in various applications where such characteristics are required because the ink receiving layer has surface glossiness. For example, the inkjet recording sheet of the present invention can form an image of high quality similar to that of silver-based photographic printing paper, and thus is suitable for use as photographic paper.

In the ink jet recording sheet of the present invention, the glossiness of the surface of the ink receiving layer measured according to JIS P 8142: 2005 (paper and paper board-measurement method of mirror glossiness at 75 degrees) is 30% or more. For example, it may be 35% or more, 40% or more, 45% or more, and 50% or more.
The upper limit of the glossiness of the surface of the ink receiving layer is not particularly limited. For example, the glossiness of the surface of the ink receiving layer may be 65% or less. Such an inkjet recording sheet can be manufactured more easily.

  The inkjet recording sheet of the present invention is not particularly limited as long as the substrate and the ink receiving layer are provided. For example, the inkjet recording sheet may be calendered (smoothed) or high-speed super calendered.

The calendering treatment is a treatment for smoothing by pressing the surface of the sheet, and may simultaneously heat the surface of the sheet. The high-speed super calendar processing is to perform the 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.

In the calendered inkjet recording sheet, the surface of the ink receiving layer is smoothed. Therefore, such an inkjet recording sheet usually deteriorates in the drying property of the ink in the ink receiving layer more than the inkjet recording sheet which has not been subjected to the calendering process.
On the other hand, the ink jet recording sheet of the present invention is provided with the ink receiving layer having the above-described limited composition, so that the ink drying layer in the ink receiving layer has a good drying property even if it is calendered. It is.

<Ink receiving layer>
The ink receiving layer can be formed using a composition for an ink receiving layer containing components for constituting the same. More specifically, the ink receiving layer can be formed by applying the composition for the ink receiving layer on a substrate and drying it.

  The ratio of the contents of the components which do not vaporize at normal 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, "normal temperature" means the temperature which does not cool or heat especially, ie, the normal temperature, for example, the temperature of 15-25 degreeC etc. are mentioned.

The application of the composition for the ink receiving layer onto the substrate may be carried out once or in several times. In the case where coating is performed in a plurality of times, a method of further applying a composition for an ink receiving layer on the dried coating layer, and an ink receiving on the non-dried coating layer It may be any of the methods of applying 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 method for applying the composition for ink receiving layer is not particularly limited, and any method may be used as long as it can apply a liquid. Specific coating methods include, for example, various coaters such as an air knife coater, curtain coater, die coater, blade coater, blade coater, roll coater, gate roll coater, bar coater, rod coater, gravure coater, gravure offset coater, etc .; There are known methods using an apparatus such as a coater.

  The composition for an ink receptive layer applied may be dried by a known method such as air flow drying or heat air flow drying. The conditions such as the drying temperature and the drying time may be appropriately set according to the drying method.

Formation of the ink receiving layer on the substrate is preferably 2 g / ^{m 2} or more, more preferably 2.4 g / ^{m 2} or more, in particular not less 2.8 g / ^{m 2} or more preferable. When the formation amount of the ink receiving layer is equal to or more than the lower limit value, for example, the effect of suppressing ink bleeding is further enhanced, and in particular, when the surface of at least the ink receiving layer is smoothed using a calendar device. In addition, such effects are higher.
On the other hand, the upper limit of the formation amount of the ink receiving layer on the substrate is not particularly limited. For example, the amount of the ink receiving layer formed on the substrate may be any of 30 g / m ² or less, 25 g / m ² or less and 20 g / m ² or less.

The formation amount of the ink receiving layer can be appropriately adjusted within a range which is set by arbitrarily combining any of the preferable lower limit value and the upper limit value described above. For example, the formation amount of the ink receiving layer may be preferably ^{2 to} 30 g / m ² , more preferably 2.4 to 25 g / m ² , and particularly preferably 2.8 to 20 g / m ² . These are an example.

  The formation amount of the ink receiving layer can be adjusted, for example, by adjusting the coating amount of the composition for the ink receiving layer on the substrate, or the blending amount of each component of the composition for the ink receiving layer, etc. .

In the ink jet recording sheet of the present invention, the value of the formed amount (g / m ² ) of the ink receiving layer on the substrate is the thickness (μm) of the formed ink receiving layer, It will be the same.

The ink jet recording sheet of the present invention may be provided on only one surface of the substrate as long as the ink receiving layer is provided on at least one surface of the substrate, or may be provided on both surfaces.
When the ink jet recording sheet of the present invention has the ink receiving layer on both sides of the substrate, the two ink receiving layers may be identical to or different from each other.

<Composition for ink receiving layer>
Examples of the composition for the ink receiving layer include those containing the pigment, a binder, hollow particles, and, if necessary, other components that do not correspond to any of these.
Each component will be described below.

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

Among calcium carbonates, ground calcium carbonate and light calcium carbonate are present.
Heavy calcium carbonate is obtained by crushing and classifying natural limestone.
Light calcium carbonate is chemically synthesized, and the shape and size of its particles can be controlled chemically. The shape of the light calcium carbonate particles is usually cubic, spindle or columnar, and the like. Light calcium carbonates include those in which primary particles exist as single particles and those in which primary particles are aggregated to form secondary particles.
Light calcium carbonate in which primary particles are aggregated to form secondary particles is referred to as aggregated light calcium carbonate. The average particle size (average primary particle size) of the primary particles is determined, for example, from the observation result with a scanning electron microscope. The average particle size of the secondary particles can be determined, for example, by measurement using a laser diffraction method.
In the present invention, as the pigment, first aggregated light calcium carbonate and second aggregated light calcium carbonate having different average secondary particle diameters from each other are used.

The average secondary particle diameter 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 However, these are merely examples.
On the other hand, the lower limit value of the average secondary particle diameter of the first aggregated light calcium carbonate is not particularly limited. For example, the average secondary particle diameter may be 0.2 μm or more.
When the ink receiving layer contains the first aggregated light calcium carbonate, the effect of suppressing ink bleeding when ink jet printing is performed on the ink jet recording sheet is further enhanced.

The average secondary particle diameter of the second aggregated light calcium carbonate is preferably 2 to 5 μm, more preferably 2.3 to 4.7 μm, for example, 2.6 to 4.4 μm and 3 to 3 μm. Although any of 4 micrometers may be sufficient, this is an example.
When the ink receiving layer contains the second aggregated light calcium carbonate, the drying property of the ink when ink jet printing is performed on the ink jet recording sheet is further enhanced. Here, "the drying property of the ink is high" means that "the time required to dry the ink is short".

It is preferable that the ink receiving layer contains, as the first aggregated light calcium carbonate and the second aggregated light calcium carbonate, one having any of the above-mentioned average secondary particle sizes in combination as appropriate. For example, as a preferable combination of the first aggregated light calcium carbonate and the second aggregated light calcium carbonate in the ink receiving layer, the first secondary particle having an average secondary particle diameter of less than 1 μm (eg, 0.2 μm or more and less than 1 μm) A combination of aggregated light calcium carbonate and second aggregated light calcium carbonate having an average secondary particle diameter of 2 to 5 μm can be mentioned, but this is an example.
As described above, when the ink receiving layer contains both the first aggregated light calcium carbonate and the second aggregated light calcium carbonate, the ink jet recording sheet can be inked even when color printing is performed by a high speed ink jet printer. The drying property of the

  In the composition for ink receiving layer and the ink receiving layer, the ratio of [content (mass) of first aggregated light calcium carbonate]: [content (mass) of second aggregated light calcium carbonate] 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. When the ratio of [content (mass) of first aggregation light calcium carbonate]: [content (mass) of second aggregation light calcium carbonate] is in the above-mentioned range, the ink jet recording sheet is obtained Both the improvement of the effect of suppressing the bleeding and the improvement of the drying property can be achieved in a more balanced manner, and the ink jet recording sheet has better ink drying properties even when color printing is performed by a high speed ink jet printer. Become.

  In the composition for ink receptive layer and the ink receptive layer, the content of the first aggregated light calcium carbonate is preferably high in that the effect of suppressing ink bleeding is further increased. Thus, when the content of the first aggregated light calcium carbonate is large, [the first aggregated light calcium carbonate content (mass)]: [the second aggregated light calcium carbonate content (mass)] The ratio may be, for example, any of 53:47 to 90:10, 58:42 to 84:16, and 63:37 to 78:22, but these are an example.

  On the other hand, in the composition for ink receptive layer and the ink receptive layer, the content of the second aggregated light calcium carbonate is preferably high in that the drying property of the ink becomes higher. Thus, when the content of the second aggregated light calcium carbonate is large, the content of the first aggregated light calcium carbonate (mass): the content of the second aggregated light calcium carbonate (mass) The ratio may be, for example, any of 47: 53 to 10: 90, 42: 58 to 16: 84, and 37: 63 to 22: 78, but these are an example.

The composition for ink receptive layer and the ink receptive 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 pigments include inorganic pigments, and more specifically, non-aggregated light calcium carbonate (ie, light calcium carbonate in which primary particles are not aggregated to form secondary particles); Calcium carbonates other than the first and second aggregated light calcium carbonates, such as the above-mentioned ground calcium carbonate, may 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, The combination and ratio of may be suitably selected according to the purpose.

  In the composition for ink receptive layer and the ink receptive layer, the ratio of the total content of the first and second aggregated light calcium carbonates to the total content of the pigment is preferably 92% by mass or more, and 94% by mass It is more preferable that it is the above, It is more preferable that it is 96 mass% or more, It is especially preferable that it is 98 mass% or more, 100 mass% may be sufficient.

In the composition for the ink receiving layer, the ratio of the content of the pigment (that is, the content of the pigment in the ink receiving layer) to the total content of components other than the solvent described later is preferably 60 to 93% by mass It is more preferable that it is 65-88 mass%, and it is especially preferable that it is 70-83 mass%. The effect by using a pigment is acquired more notably by the said ratio being more than the said lower limit. Further, when the ratio is equal to or less than the upper limit value, the strength of the ink receiving layer becomes higher.
In the present specification, “content of pigment” refers to all pigments used including the other pigments as well as the first and second aggregated light calcium carbonate, unless otherwise specified. By content is meant the total content of the pigment.

  As one example particularly preferable for the composition for ink receptive layer and the ink receptive layer, a first aggregated light calcium carbonate having an average secondary particle size of less than 1 μm and a second one having an average secondary particle size of 2 to 5 μm And the content of the first aggregated light calcium carbonate (mass): the ratio of the content of the second aggregated light calcium carbonate (mass) is from 22:78 to 78:22.

[binder]
The binder is a component for retaining the pigment (first and second aggregated light calcium carbonate and the like) contained in the ink receiving layer.
The composition for ink receptive layer and the ink receptive layer contain, as the binder, polyvinyl alcohol having a degree of saponification of 97 mol% or more.
Polyvinyl alcohol is a component that largely affects the drying property and the surface gloss of the ink in the ink receiving layer. Polyvinyl alcohol is also a component that can affect the strength of the ink receiving layer.

  The polyvinyl alcohol may be, for example, either fully saponified polyvinyl alcohol or partially saponified polyvinyl alcohol.

The saponification degree of polyvinyl alcohol is 97 mol% or more, preferably 97.3 mol% or more, more preferably 97.6 mol% or more, and 97.8 mol% or more Particularly preferred. When the degree of saponification of polyvinyl alcohol is at least the lower limit value, the drying property of the ink in the ink receiving layer becomes high.
The upper limit value of the degree of saponification of polyvinyl alcohol is not particularly limited. For example, the degree of saponification of polyvinyl alcohol may be 100 mol% or less, 99.8 mol% or less, 99.6 mol% or less, and 99.3 mol% or less.

  The degree of saponification of polyvinyl alcohol can be appropriately adjusted within the range set by arbitrarily combining any of the above-mentioned preferable lower limit value and upper limit value. For example, the saponification degree of polyvinyl alcohol is preferably 97 to 100 mol%, more preferably 97.3 to 99.8 mol%, still more preferably 97.6 to 99.6 mol%, particularly preferably 97.8 Although -99.3 mol% may be sufficient, these are an example.

  The polymerization degree of polyvinyl alcohol is preferably 300 to 3000, more preferably 350 to 2800, still more preferably 400 to 2600, and particularly preferably 450 to 2450. When the degree of polymerization of the polyvinyl alcohol is at least the lower limit value, the strength of the ink receiving layer becomes higher. In addition, when the polymerization degree of polyvinyl alcohol is equal to or less than the upper limit value, the drying property of the ink in the ink receiving layer becomes higher.

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

Examples of the water-soluble polymer include modified polyvinyl alcohol such as cation modified polyvinyl alcohol, anion modified polyvinyl alcohol, silanol modified polyvinyl alcohol, oxidized starch, phosphate esterified starch, rhoconsu, casein, carboxymethyl cellulose (CMC), ester Polyurethanes such as polyurethanes and carbonate polyurethanes can be mentioned.
The polyurethane may be, for example, any of cationic, anionic and nonionic.

  The polyvinyl alcohol and the other binders may be used alone or in combination of two or more. When two or more are used in combination, the combination and ratio thereof depend on the purpose. It may be selected appropriately.

  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 binder is preferably 80% by mass or more, and more preferably 85% by mass or more. The content is more preferably 90% by mass or more, and particularly preferably 95% by mass or more. For example, it may be 98% by mass or 100% by mass.

  In the composition for ink receptive layer and the ink receptive layer, the ratio of the content of the polyvinyl alcohol to the total content of the first and second aggregated light calcium carbonates is 4 to 13.5% by mass, 4 The content is preferably from 4.1 to 13.3% by mass, and more preferably from 4.8 to 13.1% by mass. When the ratio is equal to or more than the lower limit value, the strength of the ink receiving layer is increased. In addition, when the ratio is equal to or less than the upper limit value, the surface gloss of the ink receiving layer becomes high.

[Hollow particles]
The hollow particles are a component for improving the surface glossiness in the ink receiving layer.
The constituent material of the hollow particles may be either an organic material or an inorganic material.
The constituent material constituting one hollow particle may be only one type, may be two or more types, and in the case of two or more types, the combination and ratio thereof depend on the purpose. Can be selected appropriately.

The hollow particles are not particularly limited as long as the entire shape is particulate and has a hollow portion. For example, one hollow particle may have only one hollow portion or two or more hollow portions.
In addition, the hollow particle may have an opening at a part of its outer shell, which connects the inside and the outside of the hollow particle. It is important that the hollow particles have a void inside, and the shape of the outer shell is not particularly limited as long as the presence of the void inside can be maintained.

  As said hollow particle which has only one hollow part per piece, the thing of the state in which the microcapsule well-known in the field | area of a pharmaceutical, an agrochemical, etc. does not contain a solvent or core substance is mentioned, for example. Such hollow particles can also be referred to as, for example, particles formed to have only one hollow portion by a film-forming component that forms the outer shell of a microcapsule.

  Examples of the hollow particles having two or more hollow portions per one include, for example, known porous particles.

The constituent material of the hollow particles is preferably an organic material, and more preferably a resin.
As said resin, the latex (natural rubber latex) which has a natural rubber as a main component, the modification | denaturation latex which has as a main component the modification rubber which modified | denatured the natural rubber, a synthetic resin etc. are mentioned.

The synthetic resin may be a homopolymer obtained by polymerizing one kind of monomer, or a copolymer obtained by copolymerizing two or more kinds of monomers.
Examples of the copolymer include styrene / (meth) acrylic acid ester copolymer, styrene / (meth) acrylic acid copolymer and the like. The styrene / (meth) acrylic acid ester copolymer is, for example, preferably a styrene / (meth) acrylic acid methyl copolymer, and more preferably a styrene / methyl methacrylate copolymer.

  In the present specification, “(meth) acrylic acid” is a concept including both “acrylic acid” and “methacrylic acid”. The same applies to terms similar to “(meth) acrylic acid”, for example, “(meth) acrylate” is a concept including both “acrylate” and “methacrylate”, “(meth) acryloyl group” "Is a concept including both" acryloyl group "and" methacryloyl group ".

  The average particle diameter of the hollow particles is not particularly limited, but is preferably 0.35 to 3 μm, more preferably 0.4 to 2.7 μm, and preferably 0.45 to 2.4 μm. Particularly preferred. When the average particle diameter of the hollow particles is at least the lower limit value, the gloss of the surface of the ink receiving layer is further enhanced, and the effect of suppressing ink bleeding in the ink receiving layer is further enhanced. When the average particle diameter of the hollow particles is less than or equal to the upper limit value, the drying property of the ink in the ink receiving layer becomes higher.

The average particle size of hollow particles is the particle size at 50% accumulation (D (D) obtained from the volume-based cumulative particle size distribution curve obtained by measuring the particle size distribution of hollow particles using a Coulter Counter. ₅₀ means the median diameter).

The hollow percentage of the hollow particles is not particularly limited, but is preferably 40 to 85%, and more preferably 50 to 80%. When the hollow ratio of the hollow particles is in such a range, the effect of using the hollow particles can be more significantly obtained.
The hollow percentage (%) of the hollow particles is calculated from the theoretical value D ₁ of the density of hollow particles and the measured value D ₂ of the density of hollow particles according to the formula “(D ₁ −D ₂ ) / D ₁ × 100”. ,Desired.

  The thickness of the shell of the hollow particle is preferably 5 to 10% of the particle diameter of the hollow particle. When the thickness of the shell of the hollow particle is in such a range, the effect of using the hollow particle can be more remarkably obtained.

  The shape of the hollow particle is not particularly limited as long as it has a particle shape and a hollow portion in the ink receiving layer. For example, the shape of the hollow particles may not coincide between the completion of the production of the hollow particles and the completion of the production of the recording sheet for inkjet. When the ink jet recording sheet is manufactured, the hollow particles may be deformed by applying a force to the hollow particles. In the present invention, even if the shape is different from the original shape due to deformation, it can be recognized that the original shape before deformation is in the form of particles, and if it has a hollow portion even after deformation, Such things are handled as hollow particles. As described above, by using the hollow particles having the shape of a particle and having the hollow portion, the inkjet recording sheet of the present invention exhibits the above-described excellent effects.

  In the composition for ink receptive layer and the ink receptive layer, the ratio of the content of the hollow particles to the total content of the first and second aggregated light calcium carbonates is 3 to 23% by mass, 3.5 It is preferable that it is -22 mass%, It is more preferable that it is 4-21 mass%, It is especially preferable that it is 4.5-20.5 mass%. When the ratio is equal to or more than the lower limit value, the surface gloss of the ink receiving layer becomes high. In addition, when the ratio is equal to or less than the upper limit value, the drying property of the ink in the ink receiving layer becomes high.

[Other ingredients]
Examples of the other components include solvents, ink fixing agents, polyvalent metal salts, pH adjusters, antifoaming agents, foam inhibitors, mold release agents, foaming agents, antioxidants, preservatives, water resistance agents, Examples of such additives include paper strength agents, color dyes, color pigments, dye fixing agents, pigment dispersants, fluorescent whitening agents, ultraviolet light absorbers, and the like, which are commonly used in the ink receiving layer of the recording sheet for ink jet recording.
One of the other components may be used alone, or two or more may be used in combination. When two or more are used in combination, the combination and ratio thereof may be appropriately selected depending on the purpose. Good.

(solvent)
To prepare the dispersion or solution when the pigment, the binder, the hollow particles, or the other components other than the solvent are blended as a dispersion or a solution to prepare a composition for an ink receiving layer When no solvent is blended other than the solvent used, the solvent means the solvent used to prepare the dispersion or solution.
On the other hand, when a solvent is separately formulated in addition to the solvent used to prepare the dispersion or solution, the solvent means the solvent used to prepare the dispersion or solution, and the solvent separately. It means both of the blended solvent.
And when all the said other components other than the said pigment, a binder, hollow particles, or a solvent are mix | blended as a solid, the said solvent means the solvent mix | blended separately from these.

  Examples of the solvent include water, alcohol and the like.

  One of the solvents may be used alone, or two or more thereof may be used in combination. When two or more are used in combination, the combination and ratio thereof may be appropriately selected depending on the purpose.

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

(Ink fixing agent)
The ink fixing agent is a component for fixing the ink in the ink receiving layer.
Examples of the ink fixing agent include cationic resins and the like that exhibit cationic properties when dissolved or dispersed in water.

  The cationic resin is preferably a monomer, an oligomer or a polymer of a primary amine, a secondary amine, a tertiary amine or a quaternary ammonium salt, and more preferably the oligomer or the polymer.

More preferable examples of the cationic resin include, for example, an alkylamine-epichlorohydrin copolymer; an acrylic polymer having a secondary amino group, a tertiary amino group or a quaternary ammonium group; polyvinyl amine; polyvinyl amidine; 5-membered ring amidines; dicyan-based cationic resins such as dicyandiamide-formalin copolymer; polyamine-based cationic resins such as dicyandiamide-polyethyleneamine copolymer; polyalkylenepolyamines such as polyethylenepolyamine and polypropylenepolyamine and derivatives thereof diallyldimethylammonium -SO ₂ copolymer; diallylamine salt -SO ₂ copolymer; diallyldimethylammonium chloride polymers; polymers of allylamine salts; vinylbenzyl triallyl ammonium salts alone Polymer or copolymer; dialkyl aminoethyl (meth) acrylate 4 Kyushiotomo polymer; acrylamide - diallylamine salt copolymers; poly aluminum chloride, aluminum salts such as poly aluminum acetate and the like.
Among them, the cationic resin is particularly preferably an alkylamine-epichlorohydrin copolymer, and most preferably a dimethylamine-epichlorohydrin copolymer.

In the present specification, the polymer also includes a polycondensation product.
Further, unless otherwise specified, the descriptions of "derivative" and "class" mean that one or more hydrogen atoms of the original compound are substituted by a group other than a hydrogen atom. Here, the "group" includes not only an atomic group formed by combining a plurality of atoms, but also one atom.

  One type of ink fixing agent may be used alone, or two or more types may be used in combination. When two or more types are used in combination, the combination and ratio thereof may be appropriately selected according to the purpose. .

  When the composition for the ink receiving layer and the ink receiving layer contain the ink fixing agent, the ratio of the content of the ink fixing agent to the content of the pigment in the composition for the ink receiving layer and the ink receiving layer is 1 to The content is preferably 40% by mass, more preferably 1 to 25% by mass, and for example, 1 to 15% by mass, 1 to 10% by mass, 1 to 6% by mass, or 1 to 4% by mass It may be. However, these ratios are an example of a preferable thing. When the ratio is equal to or more than the lower limit value, the effect of using the ink fixing agent can be more remarkably obtained. In addition, when the ratio is equal to or less than the upper limit value, excessive use of the ink fixing agent is suppressed.

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

Examples of polyvalent metal salts include calcium chloride (CaCl ₂ ), magnesium chloride (MgCl ₂ ), aluminum chloride (AlCl ₃ ), barium chloride (BaCl ₂ ), zinc chloride (ZnCl ₂ ), calcium sulfate (CaSO ₄ ) , Magnesium sulfate (MgSO ₄ ), calcium nitrate (Ca (NO ₃ ) ₂ ), magnesium acetate ((CH ₃ COO) ₂ Mg), calcium acetate ((CH ₃ COO) ₂ Ca), aluminum potassium sulfate (potassium alum, AlK (SO ₄ ) ₂ ) and the like.
The polyvalent metal salt may be a hydrate or non-hydrate.

  Among them, polyvalent metal salts can improve ink drying properties and coloring density of the ink receiving layer in the ink receiving layer, and ink jet printability such as water resistance and scratch resistance of the ink receiving layer in a well-balanced manner, and have high safety. In terms of point, calcium chloride, magnesium chloride or aluminum potassium sulfate is preferable, and in particular, aluminum potassium sulfate is preferable in that the drying property of the ink becomes higher.

  The polyvalent metal salt may be used alone or in combination of two or more. When two or more are used in combination, the combination and ratio thereof may be appropriately selected according to the purpose. Good.

  When the ink receiving layer composition and the ink receiving layer contain a polyvalent metal salt, those containing one or more selected from the group consisting of calcium chloride, magnesium chloride and potassium aluminum sulfate are preferable. Those containing aluminum potassium sulfate are more preferable, and when containing aluminum potassium sulfate, one containing one or both of calcium chloride and magnesium chloride is also more preferable. The ink receptive layer contains at least aluminum potassium sulfate, whereby 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 The content is preferably 3 to 55% by mass, more preferably 3 to 25% by mass, still more preferably 3 to 15% by mass, and particularly preferably 3 to 10% by mass. The effect by using polyvalent metal salt is more notably acquired because the said ratio is more than the said lower limit. Moreover, the excess use of a polyvalent metal salt is suppressed because the said ratio is below the said upper limit.

(Defoamer)
The antifoaming agent is not particularly limited, and may be a known one.
One of the antifoaming agents may be used alone, or two or more thereof may be used in combination. When two or more 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 ink receiving layer may be appropriately adjusted depending on the purpose.

<Method of producing composition for ink receiving layer>
The composition for the ink receiving layer can be produced by blending the pigment, the binder, the hollow particles, and the other components as needed, and sufficiently stirring the components. In the composition for the ink receiving layer, the pigment and the hollow particles are preferably dispersed, and the binder is preferably dissolved or dispersed.

There is no particular limitation on the blending order of each component.
In addition, when each component is blended, all the components may be added and then mixed, or some of the components may be sequentially added and mixed, or all the components may be sequentially added and mixed. May be
The solvent may be used as previously mixed with the pigment, the binder, the hollow particles, or the other components other than the solvent as described above, or may be used alone without being mixed with these components. You may

  However, when the composition for the ink receiving layer is produced, the surface gloss of the ink receiving layer tends to be higher by blending the pigment prior to the binder (blending the pigment and the binder in this order).

The temperature at which each component is blended is not particularly limited, and may be appropriately adjusted according to the type of the blended component and the like, but usually 15 to 30 ° C. is preferable.
Stirring may be carried out 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 for example, 10 minutes to 24 hours is preferable.

<Base material>
The material of the substrate is not particularly limited, and may be selected from those capable of forming a coating layer according to the purpose. For example, the substrate may be a water resistant substrate or a non-water resistant substrate.
As the water-resistant substrate, for example, a substrate having a residual ratio of either longitudinal or lateral in a wet tensile strength test according to JIS P8135: 1998 is 10% or more.

  Specific examples of the material of the substrate include, for example, paper such as water resistant paper, high quality paper, art paper, coated paper, cast coated paper, resin coated paper, synthetic paper, etc .; 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 Examples thereof include resins, phenolic resins, urea resins, polyurethane, and synthetic resins such as polyimide.

  The substrate may be composed of a single layer, or may be composed of two or more layers, and in the case of two or more layers, these 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. And when several layers mutually differ, the combination of these several layers is not specifically limited. Here, that the plurality of layers are different from each other means that at least one of the material and thickness of each layer is different from each other.

The thickness of the substrate is not particularly limited as long as the shape of the substrate is a sheet or film, but is preferably 20 to 1000 μm, more preferably 35 to 500 μm, and 50 to 200 μm. Is particularly preferred. When the thickness of the substrate is not less than the lower limit, the structure of the ink receiving layer can be held more stably, and when the thickness of the substrate is not more than the upper limit, the handling as an inkjet recording sheet Sex is better.
When the substrate is composed of a plurality of layers, the total thickness of each layer may be made to be the thickness of the above-mentioned preferred substrate.

  A commercial item may be used as a base material, and what was manufactured by the well-known method may be used.

<< Method for manufacturing inkjet recording sheet >>
The inkjet recording sheet of the present invention can be produced by forming an ink receiving layer on at least one surface of a substrate.
The method of forming the ink receiving layer is as described above.

  When the ink jet recording sheet of the present invention is calendered (smoothed), the calendering may be performed at least on the surface of the ink receiving layer after the ink receiving layer is formed.

  The calendar processing (smoothing processing) of the recording sheet for ink jet recording (surface of the ink receiving layer) is, for example, known machine calender, TG calender, super calender, soft calender, gloss calender, compact calender, matte super calender, matte calender etc. Can be performed using a calendar device.

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

  The conditions of the calendering process are appropriately selected according to the required quality according to the temperature of the rigid roll, the calendering pressure, the number of nips, the roll speed, the paper moisture before the calendering process and the like.

  Although the processing temperature at the time of calendering is not particularly limited, it can be, for example, 10 to 50 ° C.

Although the pressure at the time of calendering is not particularly limited, it can be, for example, 50 to 400 kN / m.
The pressure at the time of calendering is adjusted, for example, by 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 pressure at the time of calendering by adjusting the distance between the roll faces is suitable for calendering on a small scale. For example, the pressure at the time of calendering can be easily adjusted by setting the distance between the roll surfaces to preferably 10 to 400 μm according to the thickness of the inkjet recording sheet to be processed.

Next, the entire configuration of the inkjet recording sheet of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing an embodiment of the ink jet recording sheet of the present invention. FIG. 2 is a cross-sectional view schematically showing another embodiment of the ink jet recording sheet of the present invention.
In FIG. 2, the same components as those shown in FIG. 1 are denoted by the same reference numerals as in FIG. 1.
Further, in the drawings used in the following description, for the sake of easy understanding of the features of the present invention, the main parts may be enlarged for convenience, and the dimensional ratio of each component is the same as the actual one. Not necessarily.

The ink jet recording sheet 1 shown in FIG. 1 is provided with the ink receiving layer 12 only on one surface (sometimes referred to as a “first surface” in this specification) 11 a of a substrate 11.
Further, the inkjet recording sheet 2 shown in FIG. 2 is on the first surface 11a of the base material 11 and the other surface (sometimes referred to as "second surface" in this specification) 11b (ie, on both surfaces) Both have the ink receiving layer 12. As to the two ink receiving layers 12 and 12 in the inkjet recording sheet 2, those provided on the first surface 11 a of the substrate 11 are shown as the first ink receiving layer 121 as needed, What is provided on the 11th second surface 11 b is shown as a second ink receiving layer 122 to be distinguished from each other.

In FIG. 1, reference numeral 12 a denotes a surface of the ink receiving layer 12 on the opposite side to the substrate 11 (sometimes referred to as “first surface” in the present specification), and reference numeral 12 b denotes ink The surface (it may be called "2nd surface" in this specification) of the base material 11 side of the receptive layer 12 is shown.
Further, in FIG. 2, reference numerals 12a, 121a and 122a denote surfaces (first surface) of the ink receiving layer 12, the first ink receiving layer 121 and the second ink receiving layer 122 on the side opposite to the substrate 11 side. 12b, 121b and 122b indicate the surface (second surface) on the substrate 11 side of the ink receiving layer 12, the first ink receiving layer 121 and the second ink receiving layer 122, respectively.

  1 and 2, the substrate 11 and the ink receiving layer 12 (the first ink receiving layer 121 and the second ink receiving layer 122) are as described above.

  However, 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.

In the ink jet recording sheet of the present invention, the ink receiving layer may be provided on the entire surface of the surface to be formed on the substrate, or may be provided only in a partial region.
The surface area of the ink receiving layer may be equal to or less than the surface area of the substrate when the ink jet recording sheet of the present invention is viewed in plan from the upper side of the side provided with the ink receiving layer. There is no particular limitation as long as the condition is satisfied. The shapes of the ink receiving layer and the substrate when viewed in plan in this manner can also be arbitrarily set according to the purpose, and are not particularly limited. For example, the shapes of the ink receiving layer and the substrate when viewed in such a manner may be similar to each other or may not be similar to each other.

The ink jet recording sheet of the present invention may be provided with a layer other than the ink receiving layer on the substrate depending on the purpose.
As said other layer, an adhesive layer, an adhesive layer, a peeling film etc. are mentioned, for example.

  Examples of the pressure-sensitive adhesive layer and the adhesive layer include those for attaching and fixing an ink jet recording sheet to an object. When such a pressure-sensitive adhesive layer or adhesive layer is provided, the ink jet recording sheet preferably further includes a release film on these layers, and the pressure-sensitive adhesive layer or adhesive layer is not exposed.

As the adhesive layer, for example, after laminating the laminated surfaces of the sheets to each other, by peeling them, it is possible to make the laminated surfaces of the sheets releasable without damaging each other. There is also mentioned a pressure-sensitive adhesive layer which adheres the sheets releasably.
The pressure sensitive adhesive layer may be provided on the ink receiving layer.

  In the inkjet recording sheet provided with the pressure-sensitive adhesive layer, the sheet to be adhered may be releasably adhered to the pressure-sensitive adhesive layer, or the sheet to be adhered may be adhered. You do not have to. The ink jet recording sheet provided with the pressure sensitive adhesive layer may be in a state in which one ink jet recording sheet is folded in and releasably adhered by the pressure sensitive adhesive layer.

  Hereinafter, the present invention will be described in more detail by way of specific examples. However, the present invention is not limited at all to the examples shown below.

<Base material>
In the following examples and comparative examples, those shown below were used as the substrate.

<Raw material>
In the following examples and comparative examples, the following were used as the pigment, the binder and the hollow particles.

In the following Examples and Comparative Examples, the following materials were used as raw materials other than the pigment, the binder and the hollow particles.
[Ink Fixing Agent]
(C) -1: alkylamine-epichlorohydrin polycondensate (manufactured by Satoda Kako "Jetfix 260", molecular weight 710)
[Polyvalent metal salt]
(D) -1: calcium chloride (d) -2: potassium aluminum sulfate (potassium alum)

<< Manufacturing of inkjet recording sheets >>
Example 1
Binder (b) -2 (8.3 parts by mass (solid content)) to pigment (a) -1 (25 parts by mass) and pigment (a) -2 (75 parts by mass), hollow particles (Y) -1 (5 parts by mass), ink fixing agent (c) -1 (2.78 parts by mass (solid content)), polyvalent metal salt (d) -1 (4.29 parts by mass) and polyvalent metal salt (d) These components are dispersed by adding N.-2 (2.14 parts by mass) and stirring at 1400 rpm for 1 hour using a stirrer at normal temperature to obtain a composition for an ink receiving layer which is a dispersion liquid. The
Then, using the wire bar coater, the composition for the ink receiving layer obtained above is coated on the substrate (z) -1 and dried at 105 ° C. to obtain an ink receiving layer having a thickness of about 9 μm. The layer was formed at a formation amount of 9 g / m ² to obtain an ink jet recording sheet.
Furthermore, the ink jet recording sheet was subjected to calendering at room temperature to obtain a target ink jet recording sheet. At the time of calendering, the distance between the roll surfaces of a pair of metal rolls was set to 25 μm, and the ink jet recording sheet was passed twice between the roll surfaces to pressurize the ink jet recording sheet.

[Examples 2-14, Comparative Examples 1-7]
An ink jet recording sheet was produced in the same manner as in Example 1 except that either or both of the types and the blending amounts of the components of the composition for ink receiving layer were as shown in Table 5 or Table 6. .
In addition, the description of "-" of the column of the mixing | blending component in the following table means that the component is unblended.

[Example 15]
An ink jet recording sheet was manufactured in the same manner as in Example 2 except that the distance between the roll surfaces of the pair of metal rolls was changed to 25 μm to 100 μm at the time of calendering at room temperature.

<< Evaluation of inkjet recording sheet >>
The following items were evaluated about the ink jet recording sheet obtained above. The results are shown in Table 5.

[Dot blur]
Dot smear was evaluated by dot shape factor. The evaluation sample was printed on the ink receiving layer of the ink jet recording sheet using a desktop ink jet printer at a density of 10% (monochrome printing) so that dots of 2 cm × 2 cm do not overlap in size. Made. Then, a microscopic image of the surface of the recording sheet for ink jet recording was taken, and the image was analyzed using a dot analyzer ("DA6000" manufactured by Oji Scientific Instruments). Specifically, the peripheral length and the area of the dot were measured, and the dot shape factor was calculated by the following formula.
Dot shape factor = (perimeter length) ² / (4π × area)

  The dot shape factor is 1 when the dot is a perfect circle, and becomes larger as the shape of the dot deviates from the true circle, that is, as the dot blurs. The dot shape factor measured with a desktop inkjet printer (printing speed 250 f (76.2 m) / min) is sufficiently correlated with the dot shape factor measured with a high-speed inkjet printer (printing speed 500 f (152.4 m) / min) I confirmed in advance that there is.

The dot shape factor was calculated for about 30 dots by the above method, the average value was determined, and the dot bleeding was evaluated according to the following evaluation criteria. The results are shown in Table 7. The numerical values in parentheses in the column of “dot blur” in Table 7 are average values of dot shape factors.
(Evaluation criteria)
A: The average value of the dot shape factor is 1.8 or less, the dots are close to a perfect circle, and the bleeding of the dots is completely or highly suppressed.
B: The average value of the dot shape factor is more than 1.8 and not more than 2.0, and the bleeding of the dots is suppressed.
C: The average value of dot shape factors exceeds 2.0, and the bleeding of dots is not suppressed.

[Ink drying property]
Printing was performed using the ink jet printer on the ink receiving layer of the ink jet recording sheet with four color inks of cyan, magenta, yellow and black. More specifically, printing was performed by changing the printing density from 100% to 400% by 10% for each color.
Then, immediately after the completion of printing, a transparent polyethylene terephthalate film (100 μm in thickness) was superposed on the printing surface of the ink jet recording sheet and firmly pressed in contact.
Then, while keeping this film in close contact with the printing surface, visually observe from the side opposite to the contact surface to the printing surface, and confirm the maximum print density of the ink not transferred from the printing surface to the contact surface. The drying properties of the ink were evaluated according to the following evaluation criteria. The results are shown in Table 7. The numerical value in parenthesis in the column of "Dryability of ink" in Table 7 is the above-mentioned maximum print density. In this evaluation method, it was confirmed in advance that no variation occurs in the evaluation results as long as the film is in close contact with the printing surface.
(Evaluation criteria)
A: The maximum print density of the ink is 300% or more, the drying property is excellent, and the high-speed printability is provided.
B: The maximum print density of the ink is 190% or more and less than 300%, the drying property is good, and has high-speed printability.
C: The maximum print density of the ink is less than 190%, the drying property is poor, and the ink does not have high-speed printability.

[Surface glossiness]
The gloss of the surface of the ink receiving layer in the recording sheet for inkjet was measured according to JIS P 8142: 2005 (paper and paper board-measurement method of mirror surface glossiness at 75 degrees), and the inkjet recording sheet was evaluated according to the following evaluation criteria. The surface gloss was evaluated. The results are shown in Table 7.
(Evaluation criteria)
A: The glossiness is 50% or more, and the surface glossiness is high.
B: The glossiness is 30% or more and less than 50%, and has a good surface gloss.
C: The glossiness is less than 30% and there is no or low surface glossiness.

  As is clear from the above results, the inkjet recording sheets of Examples 1 to 15 were excellent in the effect of suppressing dot bleeding, and had excellent basic characteristics as an inkjet recording sheet. The ink jet recording sheets of Examples 1 to 15 were good in the drying property and the surface gloss of the ink. The ink jet recording sheet of Example 15 is different from the ink jet recording sheets of the other examples in that the pressure at the time of the calendering process is low, but the ink recording sheets of the example 15 have good characteristics as the ink jet recording sheets of the other examples. Had.

On the other hand, the ink jet recording sheet of Comparative Example 1 was inferior in surface glossiness because the ink receiving layer did not contain hollow particles.
In the ink jet recording sheet of Comparative Example 2, in the case of Comparative Example 1, the ratio of the content of hollow particles to the total content of the first and second aggregated light calcium carbonates in the ink receiving layer is too low. As well as poor surface gloss.
In the ink jet recording sheet of Comparative Example 3, the ratio of the content of the hollow particles to the total content of the first and second aggregated light calcium carbonates in the ink receiving layer is too high, so that the ink can be dried. It was inferior.
The ink jet recording sheet of Comparative Example 4 is inferior in surface glossiness because the ratio of the content of polyvinyl alcohol to the total content of the first and second aggregated light calcium carbonates in the ink receiving layer is too high. It was
The ink jet recording sheets of Comparative Examples 5 to 7 were inferior in the drying property of the ink because the degree of saponification of the polyvinyl alcohol contained in the ink receiving layer was too low.

  The present invention can be used as an inkjet recording sheet having surface glossiness such as photographic paper, and can also be used as an inkjet recording sheet for performing a calendering process.

  1, 2 ... recording sheet for ink jet, 11 ... substrate, 11a ... first surface of substrate, 11b ... second surface of substrate, 12 ... ink receiving layer, 12a · · · · · First surface of ink receiving layer, 12b · · · Second surface of ink receiving layer, 121 · · · First ink receiving layer, 121a · · · First surface of first ink receiving layer, 121b · · · Second surface of first ink receiving layer, 122: second ink receiving layer, 122a: first surface of second ink receiving layer, 122b: second surface of second ink receiving layer

Claims (2)

An inkjet recording sheet comprising: a substrate; and an ink receiving layer formed on at least one surface of the substrate,
The ink receiving layer contains, as a pigment, first and second aggregated light calcium carbonates having different average secondary particle sizes,
The ink receiving layer contains, as a binder, polyvinyl alcohol having a degree of saponification of 97 mol% or more,
The ink receiving layer contains hollow particles,
In 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 carbonates is 4 to 13.5 mass%,
The ink jet recording sheet, wherein the ratio of the content of the hollow particles to the total content of the first and second aggregated light calcium carbonates in the ink receiving layer is 3 to 23% by mass. The average secondary particle diameter of the first aggregated light calcium carbonate is less than 1 μm, and the average secondary particle diameter of the second aggregated light calcium carbonate is 2 to 5 μm,
In the ink receiving layer, the ratio of [the first content of the aggregated light calcium carbonate (mass)]: [the content of the second aggregated light calcium carbonate (mass)] is 22:78 to 78:22. An ink jet recording sheet according to claim 1.

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