JP2020082733A - Composition for ink receiving layer, inkjet recording sheet, and production method of inkjet recording sheet - Google Patents

Abstract

To provide a composition for an ink-receiving layer that is a liquid composition for forming an ink receiving layer in an inkjet recording sheet, in which a printing speed is not required to unnecessarily decrease during gravure off-set printing, excellent printability is shown, and an ink receiving layer having excellent drying property of the ink during inkjet printing time may be formed.SOLUTION: In a composition for ink receiving layer containing a cationic resin, a polysaccharide and water, the cationic resin is set to one kind or two kinds selected from the group consisting of polyamine and a polymer of epichlorohydrin, the polysaccharide is set to one kind or two kinds selected from the group consisting of glucose, galactose, mannose and glucuronic acid, in the composition for ink receiving layer, a ratio of a content of the cationic resin to a total mass of the composition for ink receiving layer is set to 3 to 30 mass%, and a ratio of a content of the polysaccharide to a total amass of the composition for ink receiving layer is set to 0.3 to 1.3 mass%.SELECTED DRAWING: None

Description

The present invention relates to an ink receiving layer composition, an inkjet recording sheet, and a method for producing an inkjet recording sheet.

An inkjet recording sheet to be subjected to inkjet printing usually includes a substrate and an ink receiving layer provided on the substrate. The ink receiving layer is a layer for absorbing ink to form a print or an image. The ink receiving layer can be formed by applying a liquid composition containing components necessary for fixing the ink and the like and a solvent for dispersing or dissolving these components onto a substrate and drying the composition. The method of applying the composition onto the substrate can be selected from known methods depending on the purpose. Then, if necessary, the components are adjusted so that the composition has characteristics suitable for application to this coating method.

For example, when the gravure offset printing method is applied as the coating method of the composition, the composition needs to have a high viscosity to some extent. If the viscosity of the composition is too low, the composition cannot be properly placed on the roll for transferring it. Further, if the viscosity of the composition is too low, the composition tends to scatter during printing, and therefore, it is usually desirable to set the printing speed to 1000 feet/min (304.8 m/min) or more. , I can't raise it so far. In order to avoid such problems, it is desirable that the viscosity of the composition be 200 mPa·s or more.

In order to increase the viscosity of the composition, it is effective to include a thickener in the composition, for example. As such a composition, an image forming treatment liquid containing a thickener and adapted to various coating methods is disclosed (see Patent Document 1).

JP, 2003-246135, A

However, the formed ink-receptive layer may not be able to exhibit its effect sufficiently by simply adding a thickener to the composition. For example, thickeners may reduce the dryness of the ink absorbed in the ink receiving layer. In that case, the speed of ink jet printing, which is usually considered to be preferably 500 feet/min (152.4 m/min) or more, could not be increased to this level. If the printing speed during inkjet printing cannot be increased, the productivity of printed matter will be reduced.

The present invention is a liquid composition for forming an ink-receiving layer in an inkjet recording sheet, which shows good printability without needing to reduce the printing speed more than necessary during gravure offset printing. An object of the present invention is to provide an ink-receiving layer composition capable of forming an ink-receiving layer having good ink drying property during inkjet printing, and an inkjet recording sheet obtained by using the composition. ..

A first aspect of the present invention is an ink-receiving layer composition for forming an ink-receiving layer included in an inkjet recording sheet, wherein the ink-receiving layer composition comprises a cationic resin, a polysaccharide and It contains water, the cationic resin is one or more selected from the group consisting of polyamines and polycondensates of epichlorohydrin, and the polysaccharide is glucose, galactose, mannose and glucuronic acid. In the composition for the ink receiving layer, the ratio of the content of the cationic resin to the total mass of the composition for the ink receiving layer is one or more condensates selected from the group consisting of 3 to 30% by mass, and in the composition for the ink receiving layer, the ratio of the content of the polysaccharide to the total mass of the composition for the ink receiving layer is 0.3 to 1.3% by mass. A composition for an ink receiving layer.
In the first aspect of the present invention, it is preferable that the polysaccharide is one or both of guar gum and xanthan gum.

A second aspect of the present invention is an inkjet recording sheet comprising a base material and an ink receiving layer formed on at least one surface of the base material, wherein the ink receiving layer is cationic. A resin and a polysaccharide are contained, and the cationic resin is one or more selected from the group consisting of polyamine and a polycondensate of epichlorohydrin, and the polysaccharide is glucose, galactose or mannose. And one or more condensates selected from the group consisting of glucuronic acid, wherein the ratio of the content of the cationic resin to the total mass of the ink receiving layer in the ink receiving layer is 70 to An ink jet recording sheet, wherein the content of the polysaccharide is 99% by mass, and the content of the polysaccharide in the ink receiving layer is 1 to 30% by mass based on the total mass of the ink receiving layer.
In the second aspect of the present invention, it is preferable that the polysaccharide is one or both of guar gum and xanthan gum.
A third aspect of the present invention is the method for producing an inkjet recording sheet according to the second aspect, wherein the composition for an ink receiving layer according to the first aspect is subjected to a gravure offset printing method at 304.8 m/ It is a method for producing an inkjet recording sheet, which comprises a step of coating on at least one surface of a substrate at a speed of min or more.

According to the present invention, a liquid composition for forming an ink-receiving layer in an inkjet recording sheet, which exhibits good printability without needing to reduce the printing speed more than necessary during gravure offset printing. Furthermore, there are provided an ink-receiving layer composition capable of forming an ink-receiving layer having good ink drying property during inkjet printing, and an inkjet recording sheet obtained by using the composition.

FIG. 1 is a sectional view schematically showing an example of an inkjet recording sheet according to an embodiment of the present invention. It is sectional drawing which shows the other example of the inkjet recording sheet which concerns on one Embodiment of this invention typically.

<< Ink Receptor Layer Composition >>
An ink receiving layer composition according to an embodiment of the present invention is an ink receiving layer composition for forming an ink receiving layer included in an inkjet recording sheet, wherein the ink receiving layer composition is: A cationic resin, a polysaccharide, and water are contained, and the cationic resin is one or more selected from the group consisting of a polyamine and a polycondensate of epichlorohydrin, and the polysaccharide is glucose. , Galactose, mannose, and glucuronic acid, which are one or more condensates selected from the group consisting of the above-mentioned cationic properties relative to the total mass of the ink-receiving layer composition. The ratio of the content of the resin is 3 to 30% by mass, and the ratio of the content of the polysaccharide to the total mass of the composition for the ink receiving layer is 0.3 in the composition for the ink receiving layer. Is about 1.3% by mass.

The composition for the ink receiving layer of the present embodiment contains the components in the specific range of the cationic resin and the polysaccharide in the content of the specific range, so that the printing speed becomes more than necessary during the gravure offset printing. It is possible to form an ink receiving layer which does not need to be lowered, exhibits good printability, and has good ink drying properties during inkjet printing. In addition, in the present specification, the composition for the ink receiving layer is described as “gravure offset printing, in which the printing speed does not need to be reduced more than necessary during gravure offset printing”. It has printability”.

The composition for an ink receiving layer of the present embodiment is, for example, an ink receiving layer capable of suppressing ink bleeding, ink strike-through (a phenomenon in which ink permeates from the printed surface of a sheet to the opposite back surface), and the like. Can also be used to form
Hereinafter, each contained component of the composition for the ink receiving layer will be described.

<Cationic resin>
The cationic resin is one or more selected from the group consisting of polyamines and polycondensates of epichlorohydrin (also known as 3-chloro-1,2-epoxypropane).
The cationic resin is a resin that exhibits a cationic property in the presence of water.
The cationic resin is an essential component for fixing the ink in the ink receiving layer and for the ink receiving layer to exhibit its basic function. Further, the cationic resin realizes good gravure offset printing suitability in the composition for the ink receiving layer.
In the present specification, unless otherwise specified, the "cationic resin" means the above-mentioned "polyamine" or "polycondensation product of epichlorohydrin".

[Polyamine]
Examples of the polyamine in the cationic resin, for example, an amino group (-NH _2), and one or two substituted amino group in which a hydrogen atom is substituted with a group other than a hydrogen atom in the amino group, amino group or Examples of the resin include one or two or more kinds selected from the group consisting of the group in which the substituted amino group forms a salt and two or more kinds in total in one molecule.

When the polyamine has two or more substituted amino groups or groups forming the salt in one molecule, these substituted amino groups or the groups forming the salt may be the same or different from each other. Good.
In addition, in the present specification, not only the substituted amino group and the group forming the salt, but also the functional group having a plurality of options, “two or more functional groups may be the same or different from each other. “Good” means that all functional groups may be the same, all functional groups may be different, or only some of the functional groups may be the same.

The polyamine may be linear, branched (in the present specification, “linear” and “branched” are collectively referred to as “chain”) and cyclic. In the present specification, the “cyclic polyamine” means a polyamine having a cyclic structure, may have only a cyclic structure, or may have both a cyclic structure and an acyclic structure (that is, a chain structure). May be.

The positions of the amino group, the substituted amino group and the group forming the salt in the polyamine are not particularly limited.
For example, when the polyamine has a chain structure, the amino group, the substituted amino group and the group forming the salt may be present at the terminal part of the main chain or may be present at the non-terminal part. May be. In addition, in the present specification, the “main chain” means a chain structure having the largest number of atoms forming the chain structure, out of a chain structure having a single connection present in the molecule.

Examples of the polyamine include monomers, oligomers or polymers of primary amine, secondary amine, tertiary amine or quaternary ammonium salt.
As the polyamine, more specifically, for example, polyamine-epichlorohydrin polycondensate; acrylic polymer having a secondary amino group, tertiary amino group or quaternary ammonium group; polyvinylamine; polyvinylamidine; 5-membered ring Amidines; dicyandiamide-formalin copolymers and other dicyan-based cationic resins; dicyandiamide-polyethyleneamine copolymers and other polyamine-based cationic resins; polyalkylenepolyamines such as polyethylenepolyamine and polypropylenepolyamine and their derivatives; diallyldimethylammonium -SO ₂ copolymer; diallylamine salt -SO ₂ copolymer; diallyldimethylammonium chloride polymers; homopolymers or copolymers of vinyl benzyl triallyl ammonium salts; polymer of allylamine salt dialkylamino ethyl (meth) Acrylate quaternary salt copolymers; acrylamide-diallylamine salt copolymers and the like.
The polyamine-epichlorohydrin polycondensate is a polycondensate of epichlorohydrin, but in the present specification, it is treated as a polyamine rather than a polycondensate of epichlorohydrin described later.

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

Further, in the present specification, the polymer includes a polycondensate.
In addition, in the present specification, the description of “derivative” or “class” means one in which 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 combining a plurality of atoms but also one atom.

[Polycondensation product of epichlorohydrin]
The polycondensate of epichlorohydrin (excluding polyamine-epichlorohydrin polycondensate) in the cationic resin may have a constitutional unit derived from epichlorohydrin.
Examples of the polycondensate of epichlorohydrin include, for example, polycondensates of epichlorohydrin and monomers other than epichlorohydrin (in other words, structural units derived from epichlorohydrin and structural units derived from monomers other than epichlorohydrin). Resin).

The monomer other than epichlorohydrin is not particularly limited as long as it can be polycondensed with epichlorohydrin (excluding polyamine). Examples of the monomer include an amino group (—NH ₂ ), or a substituted amino group in which one or two hydrogen atoms in the amino group are substituted with groups other than hydrogen atoms, one in each molecule. The amine compound which has is mentioned.

The molecular weight of the amine compound is not particularly limited. For example, the amine compound may be a low molecular weight compound having a molecular weight of less than 10,000 or a high molecular weight compound having a molecular weight of 10,000 or more. Further, the amine compound may be either a polymer or a non-polymer. Here, "polymerization product" also includes "polycondensation product".

The positions of the amino group and the substituted amino group in the amine compound are not particularly limited.

Monomers other than epichlorohydrin constituting the polycondensate of epichlorohydrin (in other words, structural units derived from monomers other than epichlorohydrin in the polycondensate) may be only one kind, or two kinds. It may be more than two, and in the case of two or more, the combination and ratio thereof can be arbitrarily selected according to the purpose.

The monomer other than epichlorohydrin is preferably the amine compound described above, more preferably alkylamine (amine having an alkyl group), and particularly preferably dimethylamine.
That is, the polycondensate of epichlorohydrin is preferably an amine compound-epichlorohydrin polycondensate, more preferably an alkylamine-epichlorohydrin polycondensate, and particularly preferably a dimethylamine-epichlorohydrin polycondensate. ..

The cationic resin contained in the composition for the ink receiving layer may be only one kind, or may be two or more kinds, and in the case of two or more kinds, the combination and the ratio thereof may depend on the purpose. Can be selected arbitrarily.
For example, the composition for the ink receiving layer may contain only one or two or more polyamines as the cationic resin, or may contain only one or more polycondensates of epichlorohydrin. Or one or more polyamines and one or more polycondensates of epichlorohydrin may be contained together.

In the composition for the ink receiving layer, the ratio of the content of the cationic resin to the total mass of the composition for the ink receiving layer is 3 to 30% by mass, preferably 3.5 to 27% by mass, It is more preferably 4 to 24% by mass, and particularly preferably 4.5 to 22% by mass. Moreover, the said ratio may be 7.5 mass% or more, for example. When the ratio is within such a range, the composition for an ink receiving layer can form an ink receiving layer having better characteristics without deteriorating the printing speed and printability during gravure offset printing. And In particular, when the ratio is at least the lower limit value, the effect of suppressing ink bleeding in the ink receiving layer is enhanced. Further, when the ratio is not more than the upper limit value, the drying property of the composition for the ink receiving layer becomes high, and further the ink absorbability of the ink receiving layer becomes high.

<Polysaccharide>
The polysaccharide is one or more condensates selected from the group consisting of glucose, galactose, mannose and glucuronic acid. The polysaccharide is a component (that is, a thickener) for increasing the viscosity of the composition for the ink-receiving layer, and in the ink-receiving layer, the drying property of the ink is not lowered and the ink-receiving layer has a sufficient property. It is possible to exert its effect on.
In the present specification, unless otherwise specified, the "polysaccharide" means the above-mentioned "one or more condensates selected from the group consisting of glucose, galactose, mannose and glucuronic acid". means.

The polysaccharide is selected from the group consisting of a structural unit derived from glucose, a structural unit derived from galactose, a structural unit derived from mannose, and a structural unit derived from glucuronic acid. It suffices to have two or more species.
Examples of the polysaccharides include, for example, glucose, galactose, mannose, and one or more condensates selected from the group consisting of glucuronic acid (in other words, a constitutional unit derived from glucose, as a constitutional unit, Condensate having only one or more selected from the group consisting of a galactose-derived structural unit, a mannose-derived structural unit, and a glucuronic acid-derived structural unit); glucose, Condensation of one or two or more kinds selected from the group consisting of galactose, mannose and glucuronic acid, and a monosaccharide other than that (may be abbreviated as “other monosaccharide” in the present specification) Thing (in other words, as a structural unit, a structural unit derived from glucose, a structural unit derived from galactose, a structural unit derived from mannose, and a structural unit derived from glucuronic acid, from the group consisting of A condensate containing one or more selected and a structural unit derived from the other monosaccharide.

Examples of preferable polysaccharides include condensates of galactose and mannose only; condensates of glucose, mannose and glucuronic acid only; galactose, mannose and condensates of other monosaccharides; glucose, mannose and glucuronic acid. And condensates of only the other monosaccharides mentioned above.

When the polysaccharide is a condensate of one or more selected from the group consisting of glucose, galactose, mannose and glucuronic acid, and the other monosaccharide, in one molecule of the polysaccharide, Ratio of the total number of glucose-derived structural units, galactose-derived structural units, mannose-derived structural units, and glucuronic acid-derived structural units to the total number of all structural units ([The total number of constituent units derived from glucose, constituent units derived from galactose, constituent units derived from mannose, and constituent units derived from glucuronic acid in one molecule of the polysaccharide. ]/[Total number of all structural units in one molecule of the polysaccharide]×100) is not particularly limited, but is preferably 80% or more, more preferably 90% or more, and 95% or more. Is particularly preferable.

The upper limit of the ratio is not particularly limited. For example, the above ratio is preferably 99% or less from the viewpoint that the effect of using the other monosaccharide is more remarkably obtained.

The other monosaccharide is not particularly limited as long as it does not correspond to any of glucose, galactose, mannose, and glucuronic acid, and can be arbitrarily selected according to the purpose.

The other monosaccharide constituting the polysaccharide (in other words, the structural unit derived from the other monosaccharide in the polysaccharide) may be only one kind or two or more kinds. In the case of two or more kinds, the combination and ratio thereof can be arbitrarily selected according to the purpose.

The weight average molecular weight of the polysaccharide is not particularly limited, but is preferably 100,000 to 80,000,000, and more preferably 150,000 to 60,000,000.
In addition, in this specification, a weight average molecular weight is a polystyrene conversion value measured by a gel permeation chromatography (GPC) method, unless otherwise specified.

The polysaccharide contained in the composition for the ink receiving layer may be only one kind, or may be two or more kinds, and in the case of two or more kinds, the combination and the ratio thereof may depend on the purpose. Can be selected arbitrarily.

Examples of preferable polysaccharides contained in the composition for the ink receiving layer include guar gum and xanthan gum.
That is, it is preferable that the polysaccharide contained in the composition for the ink receiving layer is one or both of guar gum and xanthan gum.

In the composition for the ink receiving layer, the ratio of the content of the polysaccharide to the total mass of the composition for the ink receiving layer is 0.3 to 1.3% by mass, and 0.3 to 1.1% by mass. Is more preferable, 0.3 to 0.95% by mass is more preferable, and 0.3 to 0.8% by mass is particularly preferable. When the ratio is within such a range, the composition for an ink receiving layer can form an ink receiving layer having better characteristics without deteriorating the printing speed and printability during gravure offset printing. And In particular, when the ratio is at least the lower limit value, the viscosity of the ink receiving layer composition increases. Further, when the ratio is equal to or less than the upper limit value, the ink drying property of the ink receiving layer becomes high.

<Water>
In the composition for the ink receiving layer, water is a component for dissolving or dispersing components other than water in the solvent and is removed from the ink receiving layer.
In the present specification, the solvent and the dispersion medium are collectively referred to as “solvent” unless otherwise specified.

In the composition for the ink receiving layer, the ratio of the content of water to the total mass of the composition for the ink receiving layer may be, for example, 68.7 to 96.7% by mass.

<Other ingredients>
The composition for the ink receiving layer does not correspond to any of the cationic resin, the polysaccharide, and water, and other components (in the present specification, may be abbreviated as “other components”). Yes) may be contained.
The other components are not particularly limited and can be arbitrarily selected according to the purpose.
Examples of the other component include, for example, a cationic resin other than the cationic resin (in the present specification, it may be referred to as “other cationic resin”), a polysaccharide other than the polysaccharide (the present specification). May be referred to as "other polysaccharides"), a solvent other than water, a binder, an ink fixing agent, a polyvalent metal salt, a pH adjusting agent, a defoaming agent, a defoaming agent, a releasing agent, a foaming agent. , Antioxidants, preservatives, water resistance agents, paper strength agents, dyes, pigments, dye fixing agents, pigment dispersants, optical brighteners, ultraviolet absorbers, etc. The ingredients that may be used are mentioned.

The other component contained in the composition for the ink receiving layer may be only one type, or may be two or more types, and in the case of two or more types, the combination and the ratio thereof are intended. It can be arbitrarily selected according to.

In the composition for the ink receiving layer, the content of the other component is usually preferably 20 parts by mass or less with respect to 100 parts by mass of the total content of the cationic resin and the polysaccharide, and for example, 15 It may be any one of parts by mass or less, 10 parts by mass or less, 5 parts by mass or less, and 1 part by mass or less, and 0 parts by mass, that is, the composition for the ink receiving layer contains the above-mentioned other components. You don't have to. When the content of the other components is less than or equal to the upper limit value, the effect of using the cationic resin and the polysaccharide can be more significantly obtained.
Furthermore, the content of the other component may be further adjusted within the above range depending on the type of the other component.

[Other cationic resins]
The other cationic resin is a cationic resin which does not correspond to any of the polyamine and the polycondensation product of epichlorohydrin described above.
Other cationic resins are not particularly limited as long as this condition is satisfied.
Other cationic resins can be used as the ink fixing agent.

Examples of the other cationic resin include aluminum salts such as polyaluminum chloride and polyaluminum acetate.

The other cationic resin contained in the composition for the ink receiving layer may be only one kind, or may be two or more kinds. Can be arbitrarily selected according to.

In the composition for the ink receiving layer, the content of the other cationic resin is preferably 10 parts by mass or less, for example, 5 parts by mass or less, and 3 parts by mass with respect to 100 parts by mass of the content of the cationic resin. It may be either 1 part by mass or less and 1 part by mass or less, and 0 part by mass, that is, the ink receiving layer composition may not contain other cationic resin. When the content of the other cationic resin is less than or equal to the upper limit value, the effect of using the cationic resin can be more remarkably obtained.

[Other polysaccharides]
The other polysaccharide is a polysaccharide that does not correspond to the one or more condensates selected from the group consisting of glucose, galactose, mannose and glucuronic acid described above.
Other polysaccharides are not particularly limited as long as this condition is satisfied.
Other polysaccharides can be used as a thickener, a binder, etc., for example.

Examples of other polysaccharides include oxidized starch, phosphoric acid esterified starch, low cons and the like.

The other polysaccharide contained in the composition for the ink receiving layer may be only one kind, or may be two or more kinds, and in the case of two or more kinds, the combination and the ratio thereof are intended. It can be arbitrarily selected according to.

In the composition for the ink receiving layer, the content of the other polysaccharide is preferably 10 parts by mass or less, for example, 5 parts by mass or less and 3 parts by mass, relative to 100 parts by mass of the content of the polysaccharide. It may be either 1 part by mass or less or 1 part by mass or less, and 0 part by mass, that is, the composition for the ink receiving layer may not contain other polysaccharides. When the content of the other polysaccharide is less than or equal to the upper limit value, the effect of using the polysaccharide can be more remarkably obtained.

[Solvents other than water]
The solvent other than water is a liquid at room temperature, and is not particularly limited as long as it is a component other than water among components used as a solvent or a dispersion medium.
In addition, in this specification, "normal temperature" means a temperature at which it is not particularly cooled or heated, that is, a normal temperature, and examples thereof include a temperature of 15 to 25°C.

In the present embodiment, in order to produce the composition for the ink receiving layer, the cationic resin, the polysaccharide, or the other component other than the solvent, when blended as a dispersion or solution, the dispersion or When a solvent (excluding water) other than the solvent used to prepare the solution is not mixed, the solvent other than water is used to prepare the dispersion or solution. It means the solvent (excluding water) used for.
On the other hand, when a solvent (excluding water) other than the solvent used for preparing the dispersion or solution is separately mixed, the solvent other than water means the dispersion. It means both a solvent (excluding water) used for preparing a product or a solution and this separately blended solvent (excluding water).
Then, the cationic resin, the polysaccharide, and the other components other than the solvent, when all are blended as a solid, with the solvent other than water, a solvent formulated separately from these (however water Excluding).

Examples of the solvent other than water include alcohol and the like.

The solvent other than water contained in the composition for the ink receiving layer may be only one kind, or may be two or more kinds, and in the case of two or more kinds, the combination and the ratio thereof are intended. It can be arbitrarily selected according to.

[PH adjuster]
Examples of the pH adjuster include bases.
Since the composition for the ink receiving layer contains the cationic resin, it usually tends to be acidic. Therefore, at the time of gravure offset printing, if the printing apparatus has iron components as its components, the iron components will corrode (generate rust) unless washed after printing. Then, the printing performance of the printing apparatus in which the components are corroded may be significantly deteriorated.

Examples of the iron component include, but are not limited to, a shaft portion and a gear portion of a gravure roller.
The reason why the printing device is provided with iron as its component parts is, for example, to maintain the mechanical strength of the printing device.

On the other hand, by using a composition for an ink receiving layer containing a base and having a reduced acidity or a non-acidic property, at the time of gravure offset printing, a printing device equipped with iron components is used to print. The corrosion of the iron component can be suppressed and the deterioration of the printing performance of the printing apparatus can be avoided without performing the subsequent cleaning.

The base is preferably a strong base.
The base preferably has a solubility of 70 g/100 mL or more in water, more preferably 100 g/100 mL or more. The base preferably has these solubilities in water at 18 to 23°C.

Examples of the preferable base include sodium hydroxide, potassium hydroxide and the like.

The ink-receiving layer composition may contain only one type of base, or two or more types of bases, and in the case of two or more types, the combination and ratio thereof are optional depending on the purpose. You can choose to.

Preferred examples of the ink receiving layer composition containing a base include those containing one or both of sodium hydroxide and potassium hydroxide.

When a base is used, in the composition for the ink receiving layer, the ratio of the content of the base to the total mass of the composition for the ink receiving layer is preferably 0.4 to 1.2% by mass. When the ratio is at least the lower limit value, the effect of using the base in the composition for the ink-receiving layer becomes higher. When the ratio is less than or equal to the upper limit value, the effect of avoiding the inclusion of a solid matter (insoluble matter) in the ink receiving layer composition (increasing solubility) is improved, and the ink receiving layer composition The coating suitability of is improved.
The ratio may be further adjusted within the above numerical range, for example, depending on the type of base used.

The degree of the corrosion inhibition effect of the ink receiving layer composition is determined by, for example, immersing iron in the ink receiving layer composition, and measuring the absorption spectrum of the ink receiving layer composition before and after the immersion in a specific wavelength range. , L ^* a ^* b ^* L ^* , a ^*, and b ^* values in the color system were calculated, and the color difference (ΔE) of the ink receiving layer composition before and after immersion was calculated from these calculated values. Can be evaluated.
This evaluation method utilizes that when the corrosion inhibiting effect on the iron of the composition for the ink receiving layer is low, the tint of the composition for the ink receiving layer greatly changes with the fast corrosion rate of iron. Then, the degree of the corrosion inhibition effect of the composition for the ink receiving layer is evaluated from the degree of change in the tint.
More specifically, it is as follows.

That is, for example, the composition for the ink receiving layer and iron are mixed in a mass ratio of [composition for the ink receiving layer (parts by mass)]:[iron (parts by mass)]=85:15, and iron is mixed into the ink. The iron and the composition for the ink receiving layer were allowed to stand for 72 hours under a temperature condition of 28° C. while being immersed in the composition for the receiving layer in this state, and the composition for the ink receiving layer before and after the immersion was The absorption spectrum is measured in the wavelength range of 380 to 780 nm, the values of L ^* , a ^*, and b ^* in the L ^* a ^* b ^* color system are calculated, and from these calculated values, the ink receiving layer before and after immersion. The color difference (ΔE) of the composition for ink is calculated, and the corrosion inhibition effect of the composition for the ink receiving layer can be evaluated by the calculated value.

The color difference (ΔE) of the ink receiving layer composition before and after the immersion of iron is L ₀ ^* , a ₀ of the values of L ^* , a ^* and b ^* of the composition for the ink receiving layer before the immersion of iron, respectively. ^* and the _b ^{0 *,} the ink-receiving layer composition after immersion of the iron ^L *, ^{a *} and ^{b *} values, _{respectively,} ^L 1 _*, when the _a ^{1 *} and _b ^{1 *,} the following formula :
ΔE=[(L ₁ ^* -L ₀ ^* ) ² +(a ₁ ^* -a ₀ ^* ) ² +(b ₁ ^* -b ₀ ^* ) ² ] ^1/2
Can be calculated by

The corrosion inhibiting effect of the ink receiving layer composition, for example, using a test ink receiving layer composition which is the same as the intended ink receiving layer composition except that it does not contain a polysaccharide, You may evaluate. This is because it may not be possible to calculate accurate values of L ^* , a ^*, and b ^* in a composition having a high viscosity for an ink receiving layer, while a polysaccharide may inhibit corrosion of the composition for an ink receiving layer. This is because there is no or very little effect on the effect.

The ΔE of the ink receiving layer composition of the present embodiment is preferably 40 or less, more preferably 7 or less, and further preferably 1 or less.
The corrosion inhibiting effect of the ink receiving layer composition having ΔE of 1 or less is extremely high, and the corrosion rate of iron is equivalent to that of stainless steel.
Although the corrosion inhibitory effect of the ink receiving layer composition having ΔE of more than 1 and 7 or less is inferior to the case of ΔE of 1 or less, the corrosion rate of iron is high, and the corrosion rate of iron is It is equivalent to the corrosion rate.
The corrosion inhibiting effect of the ink receiving layer composition having ΔE of more than 7 and 40 or less is inferior to that when ΔE is 1 or less, and iron is used in the ink receiving layer composition in an environment of 28° C. Corrosion will start after about 12 hours of contact with, but by using other measures (except cleaning of iron components after printing), the printing performance of printing devices equipped with iron components will deteriorate. do not do.
Iron starts to corrode when contacted with the composition for an ink receiving layer having ΔE of more than 40 in an environment of 28° C. for 1 to 2 hours, and other measures (however, cleaning iron components after printing should be performed). However, the printing performance of the printing apparatus including the iron component may deteriorate.

The absorption spectrum of the composition for the ink receiving layer can be measured by using a spectrophotometer, and the measured values are used to calculate the values of L ^* , a ^* and b ^{* in} the L ^* a ^* b ^* color system. it can.

The composition for the ink receiving layer of the present embodiment has a high viscosity and is suitable for applying the gravure offset printing method.
The viscosity of the composition for the ink receiving layer measured with a B-type viscometer in an environment of 23° C. is preferably 200 Pa·s or more, for example, 300 Pa·s or more, 400 Pa·s or more, It may be any of 500 Pa·s or more, 600 Pa·s or more, and 700 Pa·s or more, or 1200 Pa·s or more. The composition for the ink receiving layer has a good gravure offset printability by virtue of its viscosity of 200 Pa·s or more.
The viscosity of the composition for the ink receiving layer can be measured by using a B-type viscometer, for example, according to JIS Z 8803:2011.

The viscosity of the composition for the ink receiving layer is preferably 1600 Pa·s or less from the viewpoint of further improving the gravure offset printing suitability.

The composition for the ink receiving layer has good solubility, a small amount of solid matter is deposited or is not recognized, and the deposition of solid matter is suppressed. It is suitable for application to coating methods.

<<Method for producing composition for ink receiving layer>>
The composition for the ink receiving layer can be produced by mixing the above-mentioned cationic resin, polysaccharide, water and, if necessary, the above-mentioned other components and sufficiently stirring these components.

The mixing order of each component is not particularly limited.
At the time of blending each component, all components may be added and then mixed, or some components may be sequentially added and mixed, or all components may be sequentially added and mixed. Good.
Water and the other solvent may be pre-mixed with the other components other than the cationic resin, the polysaccharide, or the solvent, as described above, or may be pre-mixed with these components. It may be used alone without performing.

The temperature at the time of blending each component is not particularly limited and may be appropriately adjusted according to the type of the blending component, etc., but is usually preferably 15 to 30°C.
The mixing method is not particularly limited, a method of mixing by rotating a stirrer or a stirring blade, a method of mixing using a mixer, a three-roll, a kneader or a bead mill, a method of adding ultrasonic waves and the like, It may be appropriately selected from known methods.
The mixing time may be appropriately adjusted according to the total amount of the ink-receiving layer composition to be produced, the mixing method, etc., and is preferably 10 minutes to 24 hours, for example.

<<Inkjet Recording Sheet, Method for Manufacturing Inkjet Recording Sheet>>
An inkjet recording sheet according to an embodiment of the present invention is an inkjet recording sheet including a base material and an ink receiving layer formed on at least one surface of the base material. The layer contains a cationic resin and a polysaccharide, the cationic resin is one or more selected from the group consisting of a polyamine and a polycondensate of epichlorohydrin, and the polysaccharide is One or more condensates selected from the group consisting of glucose, galactose, mannose and glucuronic acid, wherein the content of the cationic resin relative to the total mass of the ink receiving layer in the ink receiving layer is The ratio is 70 to 99 mass %, and the ratio of the content of the polysaccharide in the ink receiving layer is 1 to 30 mass% with respect to the total mass of the ink receiving layer.

The ink receiving layer in the inkjet recording sheet of the present embodiment is formed using the above-mentioned composition for ink receiving layer. Therefore, the ink jet recording sheet of the present embodiment has good ink drying properties during ink jet printing, and the printing speed during ink jet printing may be, for example, 152.4 m/min (500 feet/min) or more. It is possible and suitable for high-speed printing.
Hereinafter, the configuration of the inkjet recording sheet and the method for manufacturing the same will be described.

<Substrate>
The constituent material of the base material 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.
Examples of the water resistant base material include a base material having a residual rate of 10% or more in either a longitudinal grain or a lateral grain in a wet tensile strength test according to JIS P8135:1998.

Specific examples of the constituent material of the substrate include papers such as water resistant paper, coated paper, fine paper, art paper, cast coated paper, resin coated paper, synthetic paper; polyethylene, polypropylene, polyvinyl chloride, polystyrene. , Polyvinyl acetate, acrylic resin, AS resin, ABS resin, polyamide, polyacetal, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyphenylene sulfide, polysulfone, polycarbonate, epoxy resin, Examples thereof include synthetic resins such as melamine resin, phenol resin, urea resin, polyurethane and polyimide.

The base material may be composed of a single layer, or may be composed 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.
In addition, in this specification, not only in the case of a base material, “a plurality of layers are different from each other” means that at least one of a constituent material and a thickness of each layer is different from each other.

The thickness of the substrate is not particularly limited as long as the substrate has a sheet shape or a film shape, but is preferably 20 to 1000 μm, more preferably 35 to 500 μm, and 50 to 200 μm. Is particularly preferable. When the thickness of the base material is at least the above lower limit, the structure of the ink receiving layer can be held more stably. When the thickness of the substrate is equal to or less than the above upper limit, the handleability as an inkjet recording sheet becomes better.
When the substrate is composed of a plurality of layers, the total thickness of each layer may be the preferable thickness of the substrate.

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

<Ink receiving layer>
The ink receiving layer can be formed by applying the composition for the ink receiving layer on a substrate and drying the composition.
The coating of the composition for the ink receiving layer on the substrate may be performed once or may be performed in plural times. When the coating is performed in plural times, a method of further coating the composition for the ink receiving layer on the dried coating layer, and a method of further coating the ink on the non-dried coating layer Any method of applying the layer composition may be used.
The coating amount of the composition for the ink receiving layer may be appropriately adjusted in consideration of the contents of the cationic resin and the polysaccharide, the thickness of the ink receiving layer and the like in the composition for the ink receiving layer.

The method for applying the composition for the ink receiving layer is not particularly limited, and any method that can apply the liquid material may be used, but the gravure offset printing method is preferable.
Since the composition for the ink receiving layer has a high viscosity unlike the conventional composition, when the gravure offset printing method is applied, the composition for the ink receiving layer should be normally placed on the roll for transferring the composition. You can Furthermore, the composition for the ink receiving layer is less likely to scatter during printing even when gravure offset printing is performed at high speed. As described above, the composition for the ink receiving layer has gravure offset printing suitability, and by applying the gravure offset printing method, the effect of the present invention is most exerted when the ink receiving layer is formed.

In the present embodiment, by using the composition for an ink receiving layer having a high viscosity, the printing speed in the gravure offset printing method can be set to, for example, 304.8 m/min (1000 feet/min) or more. Therefore, high-speed printing is possible.

The coated ink-receiving layer composition may be dried by a known method such as blast drying or heat blast drying. The conditions such as the drying temperature and the drying time may be appropriately set according to the drying method. For example, in the case of performing heating air drying, the heating temperature is preferably 80 to 120, and the heating time is preferably 30 seconds to 3 hours. However, this drying condition is an example.

The ink receiving layer contains a cationic resin and a polysaccharide.
The cationic resin contained in the ink receiving layer is the same as the cationic resin contained in the composition for the ink receiving layer, and one or two kinds selected from the group consisting of polyamine and polycondensation product of epichlorohydrin. That is all. Further, the polysaccharide contained in the ink receiving layer is the same as the polysaccharide contained in the composition for the ink receiving layer, and one or more kinds selected from the group consisting of glucose, galactose, mannose and glucuronic acid. It is a condensate.

The cationic resin contained in the ink receiving layer may be only one kind, or may be two or more kinds, and in the case of two or more kinds, the combination and the ratio thereof may be arbitrarily selected depending on the purpose. You can choose.
For example, the ink receiving layer may contain only one or two or more polyamines as the cationic resin, or may contain only one or two or more polycondensates of epichlorohydrin. It is good, and one or two or more polyamines and one or more polycondensates of epichlorohydrin may be contained together.

The polysaccharide contained in the ink receiving layer may be only one kind, or may be two or more kinds, and in the case of two or more kinds, their combination and ratio may be arbitrarily selected depending on the purpose. You can choose.

Preferred examples of the polysaccharide contained in the ink receiving layer include guar gum and xanthan gum.
That is, it is preferable that the polysaccharide contained in the ink receiving layer is one or both of guar gum and xanthan gum.

The content ratio of the components that do not vaporize at room temperature in the composition for the ink receiving layer is usually the same as the content ratio of the components in the ink receiving layer.

Therefore, in the ink receiving layer, the ratio of the content of the cationic resin to the total weight of the ink receiving layer is 70 to 99% by mass, and preferably 80 to 98.6% by mass, 85 ˜98.3% by mass is more preferred, and 90 to 98% by mass is particularly preferred.

In the ink receiving layer, the ratio of the content of the polysaccharide to the total weight of the ink receiving layer is 1 to 30% by mass, preferably 1.3 to 20% by mass. It is more preferably 6 to 15% by mass, and particularly preferably 2 to 10% by mass. When the ratio is less than or equal to the upper limit value, the drying property of the ink in the ink receiving layer becomes higher.

The ink receiving layer contains another component (which may be abbreviated as “other component” in the present specification) which does not correspond to either the cationic resin or the polysaccharide. May be.
The other component contained in the ink receiving layer is the same as the other component contained in the composition for the ink receiving layer except for the solvent other than water.

The other component contained in the ink receiving layer may be only one kind, or may be two or more kinds, and in the case of two or more kinds, the combination and the ratio thereof are arbitrary depending on the purpose. You can choose to.

In the ink receiving layer, the content of the other component is usually preferably 20 parts by mass or less, for example, 15 parts by mass or less, based on 100 parts by mass of the total content of the cationic resin and the polysaccharide. It may be any one of 10 parts by mass or less, 5 parts by mass or less, and 1 part by mass or less, and 0 parts by mass, that is, the ink receiving layer may not contain the other component. When the content of the other components is less than or equal to the upper limit value, the effect of using the cationic resin and the polysaccharide can be more remarkably obtained.

Furthermore, the content of the other component may be further adjusted within the above range depending on the type of the other component.
For example, in the ink receiving layer, the content of the other cationic resin is preferably 10 parts by mass or less, for example, 5 parts by mass or less and 3 parts by mass, relative to 100 parts by mass of the content of the cationic resin. 1 part by mass or less, or 0 part by mass, that is, the ink receiving layer may not contain other cationic resin. When the content of the other cationic resin is less than or equal to the upper limit value, the effect of using the cationic resin can be more remarkably obtained.
For example, in the ink receiving layer, the content of the other polysaccharide is preferably 10 parts by mass or less, for example, 5 parts by mass or less, 3 parts by mass or less, relative to 100 parts by mass of the polysaccharide content. And 1 part by mass or less, and 0 part by mass, that is, the ink receiving layer may not contain other polysaccharides. When the content of the other polysaccharide is less than or equal to the upper limit value, the effect of using the polysaccharide can be more remarkably obtained.

The amount of the ink receiving layer formed on the substrate is preferably 0.4 g/m ² or more, more preferably 0.6 g/m ² or more, and 0.8 g/m ² or more. Is particularly preferable. When the formation amount of the ink receiving layer is not less than the lower limit value, the effect of providing the ink receiving layer can be more remarkably obtained.
On the other hand, the upper limit of the amount of the ink receiving layer formed on the substrate is not particularly limited. For example, the amount of the ink receiving layer formed on the substrate is preferably 10 g/m ² or less from the viewpoint that the ink receiving layer is not excessively formed.

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

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

The inkjet recording sheet of the present embodiment may include a base material and an ink receiving layer formed on at least one surface of the base material, and the ink receiving layer is provided only on one surface of the base material. It may be provided, or may be provided on both sides.
When the ink jet recording sheet has ink receiving layers on both sides of the substrate, these two ink receiving layers may be the same or different from each other.

That is, the inkjet recording sheet of the present embodiment can be manufactured by a manufacturing method including a step of applying the above-described composition for an ink receiving layer on at least one surface (one surface or both surfaces) of a substrate. Then, a preferred production method is to apply the above-mentioned composition for an ink receiving layer onto at least one surface (one surface or both surfaces) of a base material by a gravure offset printing method at a speed of 304.8 m/min or more. It is a manufacturing method having a process of working.

Next, the overall configuration of the inkjet recording sheet of this embodiment will be described with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing an example of the inkjet recording sheet of this embodiment. Further, FIG. 2 is a cross-sectional view schematically showing another example of the inkjet recording sheet of the present embodiment.
2, the same components as those shown in FIG. 1 are designated by the same reference numerals as in FIG.
Further, in the drawings used in the following description, in order to facilitate understanding of the features of the present invention, for the sake of convenience, there may be a case where an essential part is enlarged and the dimensional ratios of the respective constituent elements are the same as the actual ones Not necessarily.

The inkjet recording sheet 1 shown in FIG. 1 is configured by including an ink receiving layer 12 only on one surface (sometimes referred to as “first surface” in this specification) 11a of a substrate 11. ing.
The inkjet recording sheet 2 shown in FIG. 2 has both the first surface 11a of the base material 11 and the other surface (which may be referred to as a "second surface" in this specification) 11b (that is, The ink receiving layer 12 is provided on both sides). Regarding the two ink receiving layers 12 and 12 of the inkjet recording sheet 2, the one provided on the first surface 11a of the base material 11 is shown as the first ink receiving layer 121, if necessary. What is provided on the second surface 11b of 11 is shown as the second ink receiving layer 122 to be distinguished from each other.

In FIG. 1, reference numeral 12a indicates a surface of the ink receiving layer 12 opposite to the base material 11 side (may be referred to as “first surface” in the present specification), and reference numeral 12b indicates an ink receiving layer. The surface of the substrate 12 on the base material 11 side (which may be referred to as “second surface” in this specification) is shown.
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, respectively, which are opposite to the base material 11 side. , Reference numerals 12b, 121b, and 122b denote the surfaces (second surface) of the ink receiving layer 12, the first ink receiving layer 121, and the second ink receiving layer 122 on the base material 11 side, respectively.

1 and 2, the base material 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 inkjet recording sheet of the present embodiment, and the inkjet recording sheet of the present embodiment is not limited thereto.

In the ink jet recording sheet of the present embodiment, the ink receiving layer may be provided on the entire surface to be formed on the base material, or may be provided only on a part of the area.
When the inkjet recording sheet of the present embodiment 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 substrate, There is no particular limitation as long as this condition is satisfied. The shapes of the ink receiving layer and the base material when viewed in a plane as described above can also be set arbitrarily according to the purpose and are not particularly limited. For example, the shapes of the ink receiving layer and the substrate when viewed in a plane as described above may be similar to each other or may be similar to each other.

The inkjet recording sheet of the present embodiment may have a layer other than the ink receiving layer on the substrate, depending on the purpose.
Examples of the other layer include a pressure-sensitive adhesive layer, an adhesive layer, a release film, and the like.

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

As the adhesive layer, for example, the overlapping surfaces of the objects to be adhered that are initially separated from each other are adhered to each other via the adhesive layer, and then the objects to be adhered are peeled off from each other. There is also a pseudo-adhesive layer for adhering the objects to be adhered to each other so that they can be separated again without damaging the overlapping surfaces of the objects, that is, so-called re-peelable. In the present specification, the adhesion of the objects to be adhered by the pseudo adhesive layer is referred to as "pseudo-adhesion", and bringing the objects to be adhered pseudo-adhered to each other is referred to as "re-peel". ..
The pseudo adhesive layer may be provided on the ink receiving layer.

In the inkjet recording sheet provided with the pseudo adhesive layer, the object to be adhered may be removably adhered to the pseudo adhesive layer, or the object to be adhered may not be adhered. In addition, the inkjet recording sheet provided with the pseudo adhesive layer may be in a state in which one sheet of the inkjet recording sheet is folded and removably adhered by the pseudo adhesive layer.

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 described below.

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

<raw material>
In the following Examples, Comparative Examples and Reference Examples, the following were used as the cationic resin, the polysaccharide and the base.

[Example 1]
<<Production of Ink Receptive Layer Composition>>
The polysaccharide (b)-1 (0.55 g) was added to water (90.35 g) at room temperature, and the mixture was stirred for 1 hour at a stirring speed of about 500 rpm using a stirrer to give the polysaccharide (b). -1 was completely dissolved and an aqueous solution was obtained.
Then, at room temperature, the cationic resin (a)-1 (9.1 g, 5.0 g as an alkylamine-epichlorohydrin polycondensate, 4.1 g as water) was added to the obtained aqueous solution, and a stirrer was used. By stirring at a stirring speed of about 500 rpm for 10 minutes, a liquid ink receiving layer composition was obtained.

<<Manufacture of inkjet recording sheet>>
Using a bar coater, the composition for ink receiving layer obtained above is coated on one surface of the substrate (z)-1, and the coated substrate (z)-1 is The ink-receiving layer was formed by placing it in a hot air oven at 105° C. and drying it for 1 minute to obtain an inkjet recording sheet. In this inkjet recording sheet, the amount of the ink receiving layer formed on the substrate (z)-1 was ² g/m ² .

<<Evaluation of Ink Receptive Layer Composition>>
The following items were evaluated for the composition for an ink receiving layer obtained above. The results are shown in Tables 7 and 8.

<Evaluation of solubility>
The composition for the ink receiving layer was visually observed, and the solubility of the composition for the ink receiving layer was evaluated according to the following criteria.
(Evaluation criteria)
A: No solid matter was observed in the composition, and there was no turbidity.
B: A slight increase in viscosity of the composition with time or slight clouding is observed, but no solid matter is observed.
C: A slight increase in viscosity of the composition with time, or a slight white turbidity is observed, and a solid is observed.

<Measurement of viscosity>
Using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd.), the viscosity of the composition for the ink receiving layer was measured under the environment of 23° C. with the rotor rotation speed set to 30 rpm. Then, based on the measured values, the gravure offset printing suitability of the composition for an ink receiving layer was evaluated according to the following criteria.
(Evaluation criteria)
A: Viscosity is 300 mPa·s or more, and gravure offset printing suitability is high.
B: Viscosity is 200 mPa·s or more and less than 300 mPa·s, and the gravure offset printability is inferior to that in the case of “A”, but it has gravure offset printability.
C: Viscosity is less than 200 mPa·s, and it does not have gravure offset printing suitability.

<Evaluation of corrosion inhibition effect>
A test ink-receiving layer composition (solution) which was the same as the ink-receiving layer composition obtained above except that it did not contain a polysaccharide was prepared.
The composition for the test ink-receiving layer and the iron member (iron washer) thus obtained were evaluated as follows: [composition for the test ink-receiving layer (parts by mass)]: [iron member (parts by mass)]=85:15 The mass ratio was sealed in a glass bottle, and the iron member was dipped in the test ink-receiving layer composition and sealed. In this state, the iron member and the test ink-receiving layer composition were allowed to stand for 72 hours at a temperature of 28°C. As the iron member, a member whose surface had been polished and which had no corroded portion was used.

Using an ultraviolet-visible spectrophotometer (“V-770” manufactured by JASCO Corporation), a wavelength of 380 to 780 nm for the test ink-receiving layer composition before being enclosed in a glass bottle (before coexisting with an iron member). The absorption spectrum was measured in the region and the values of L ^* , a ^* and b ^* (L ₀ ^* , a ₀ ^* and b ₀ ^* ) were calculated in advance. Further, the values of L ^* , a ^* and b ^* (L ₁ ^* , a ₁ ^* and b ₁ ^* ) were calculated by the same method for the composition for a test ink receiving layer after soaking in the above state for 72 hours. did. When calculating these L ^* , a ^*, and b ^* , the condition of illuminant D65 and 2° visual field was adopted. Then, the color difference (ΔE) of the test ink-receiving layer composition before and after immersion was calculated from these calculated values. Then, from this ΔE, the corrosion inhibition effect of the ink receiving layer composition on the iron member was evaluated according to the following criteria. In addition, the numerical value in the parentheses in the column of "corrosion inhibitory effect" in Table 7 and Table 8 is said ΔE.
(Evaluation criteria)
A: ΔE≦1.
B: 1<ΔE≦7.
C: 7<ΔE≦40.
D:40<ΔE.

<<Evaluation of inkjet recording sheet>>
The following items were evaluated for the inkjet recording sheet obtained above. The results are shown in Tables 7 and 8.

<Evaluation of ink drying property>
Using an inkjet printer, printing was performed on the ink receiving layer of the inkjet recording sheet with four color inks of cyan, magenta, yellow and black. More specifically, printing was performed by changing the print density for each color in units of 10% from 100% to 400%.
Immediately after the completion of printing, a transparent polyethylene terephthalate film (thickness: 100 μm) was overlaid on the printing surface of the inkjet recording sheet and firmly pressed to bring it into close contact.
Next, while keeping this film in close contact with the printing surface, visually observing from the side opposite to the contact surface to the printing surface, and confirming the maximum print density of the ink not transferred from the printing surface to the contact surface. Then, the dryness of the ink was evaluated according to the following criteria. The values in parentheses in the column of "dryability of ink" in Tables 7 and 8 are the maximum print density. In this evaluation method, it was previously confirmed that the evaluation results did 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, it has excellent dryness, and 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 high-speed printing suitability is obtained.
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 printing suitability.

<Evaluation of suppression effect of dot bleeding>
The effect of suppressing dot bleeding was evaluated by the dot shape factor. More specifically, it is as follows.
That is, using a desktop inkjet printer, at a printing speed of 76.2 m/min (250 feet/min), dots of the aqueous black pigment ink having a size of 2 cm×2 cm do not overlap on the ink receiving layer of the inkjet recording sheet. Thus, an evaluation sample was produced by printing (monochromatic printing) at a density of 10%.
Next, a microscope image of the surface of the inkjet recording sheet was taken, and the image was analyzed using a dot analyzer (“DA6000” manufactured by Oji Scientific Instruments). Specifically, the perimeter and area of each dot were measured, and the dot shape factor was calculated by the following formula.
Dot shape factor = (perimeter) ² /(4π x area)

The dot shape coefficient is 1 when the dot is a perfect circle, and becomes larger as the shape of the dot is farther from the perfect circle, that is, as the dot is blurred. Prior to this evaluation, the dot shape factor measured using a desktop inkjet printer was set to 76.2 m/min (250 feet/min), and the printing speed was set to 152.4 m/min using a high-speed inkjet printer. It was previously confirmed that there is a sufficient correlation with the dot shape coefficient measured as (500 feet/min).

With the method described above, the dot shape coefficient was calculated for about 30 dots to obtain an average value, and the effect of suppressing dot bleeding was evaluated according to the following criteria. The numerical value in parentheses in the "dot bleeding" column in Tables 7 and 8 is the average value of the dot shape coefficient.
(Evaluation criteria)
A: The average value of the dot shape coefficient is 1.3 or less, the dots are extremely close to a perfect circle, and the blurring of the dots is most highly suppressed.
B: The average value of the dot shape factor exceeds 1.3 and is 1.5 or less, and the dot is inferior to that in the case of "A", but is considerably close to a perfect circle, and the bleeding of the dot is highly suppressed. There is.
C: The average value of the dot shape coefficient is more than 1.5 and 1.8 or less, and the dots are inferior to those in the case of “B”, but are close to a perfect circle and the blurring of the dots is suppressed.
D: The average value of the dot shape coefficient is more than 1.8 and 2.0 or less, and the blurring of dots is not slightly suppressed.
E: The average value of the dot shape coefficient exceeds 2.0, and the blurring of dots is not further suppressed as compared with the case of “D”.

<<Production and Evaluation of Ink Receptive Layer Composition, Production and Evaluation of Inkjet Recording Sheet>>
[Examples 2-35]
One of the type of the base material, the type of the blending component of the composition for the ink receiving layer, the blending amount of the blending component of the composition for the ink receiving layer, and the amount of the ink receiving layer formed on the substrate. A composition for an ink receiving layer and an inkjet recording sheet were produced and evaluated in the same manner as in Example 1 except that they were as shown in Table 5 or Table 6. The results are shown in Tables 7 and 8.
In addition, the description of "-" in the column of the blending component in Tables 5 and 6 means that the component is not blended.

<<Production and Evaluation of Inkjet Recording Sheet>>
[Comparative Example 1]
An inkjet recording sheet was produced and evaluated in the same manner as in Example 1 except that the composition for the ink receiving layer was not used. The results are shown in Table 8.

In this comparative example, since the composition for the ink receiving layer was not used, all components for obtaining the composition were not blended.

[Comparative example 2]
An inkjet recording sheet was produced and evaluated in the same manner as in Example 2 except that the composition for the ink receiving layer was not used. The results are shown in Table 8.
Also in this comparative example, since the composition for the ink receiving layer was not used, all components for obtaining the composition were not blended.

<<Production and Evaluation of Composition for Ink Receptive Layer>>
[Comparative Examples 3-6, Reference Examples 1-2]
For the ink receiving layer, the same method as in Example 1 was used except that both the types of compounding ingredients of the composition for the ink receiving layer and the compounding amounts thereof were as shown in Table 5 or Table 6. The composition was prepared and evaluated. The results are shown in Tables 7 and 8.

In Comparative Examples 3 to 6 and Reference Examples 1 and 2, inkjet recording sheets were not manufactured and evaluated as described later. In Tables 5 and 6, the description "-" in the column of the base material means that the base material was not used, and "-" in the column of the amount of ink receiving layer formed (g/m ² ). Means that the ink receiving layer was not formed. The description with "-" in the evaluation result column in Tables 7 and 8 means that the item is not evaluated.

As is clear from the above results, the ink receiving layer compositions of Examples 1 to 35 contained no solid matter, had high solubility, and had coating suitability. Further, the ink receiving layer compositions of Examples 1 to 35 had a viscosity of 229 mPa·s or higher (229 to 1469 mPa·s), a high viscosity, and were suitable for gravure offset printing. In particular, the ink receiving layer compositions of Examples 1 to 7, 10, 11, 13 to 22, 25 to 32, and 35 have a viscosity of 312 mPa·s or more (312 to 1469 mPa·s), which is higher in viscosity. Therefore, the gravure offset printing suitability was high. Further, the ink receiving layer compositions of Examples 1 to 7, 10, 11, 13 to 20 have a viscosity of 436 mPa·s or more (436 to 1469 mPa·s), a higher viscosity, and a gravure offset. The printability was particularly high.

The ink-receiving layer compositions of Examples 1 to 35 contained an alkylamine-epichlorohydrin polycondensate or a polyamine as the cationic resin, and the amount of the cationic resin content relative to the total mass of the ink-receiving layer composition was The ratio was 5 to 20 mass %.
The ink-receiving layer compositions of Examples 1 to 35 contain, as a polysaccharide, one or both of a condensate of mannose and galactose and a condensate of glucose, mannose and glucuronic acid, The ratio of the content of the polysaccharide to the total mass of the composition for the receiving layer was 0.3 to 0.75 mass %.

The ink jet recording sheets of Examples 1 to 35 had good ink drying properties and high-speed printing suitability due to the use of the above-described ink receiving layer composition. In particular, the ink jet recording sheet of Example 1 had a high ink drying property.

As described above, the ink-receiving layer compositions of Examples 1 to 35 have good printability without needing to reduce the printing speed more than necessary during gravure offset printing, and further have good printability during inkjet printing. It was possible to form an ink receiving layer having good ink drying property.

Furthermore, the inkjet recording sheets of Examples 2-35 had the effect of suppressing dot bleeding. The inkjet recording sheet of Example 1 did not have the effect of suppressing dot bleeding, but it is possible to improve dot bleeding by adjusting the blending components of the ink receiving layer composition and selecting the type of substrate. Is considered to be.

On the other hand, the ink receiving layer compositions of Examples 21 to 26, 29, 30, and 33 to 35 had the effect of inhibiting corrosion of iron members. The ink receiving layer compositions of these examples contained a base, and the ratio of the content of the base to the total weight of the ink receiving layer composition was 0.5 to 1% by mass.

On the other hand, the ink jet recording sheets of Comparative Examples 1 and 2 did not use the composition for the ink receiving layer and did not form the ink receiving layer, and thus did not have the effect brought by the ink receiving layer. Further, the ink jet recording sheet of Comparative Example 2 was inferior in ink drying property and did not have high-speed printing suitability.

The ink receiving layer compositions of Comparative Examples 3, 5 and 6 and Reference Examples 1 and 2 contained a solid substance, had low solubility, did not have coating suitability, and were not applied to a substrate. Normal coating was impossible. Therefore, in these Comparative Examples and Reference Examples, inkjet recording sheets were not manufactured and evaluated. Further, the ink receiving layer compositions of Comparative Example and Reference Example could not be measured accurately because of the influence of solids, and therefore the viscosity was not measured.

The ink-receiving layer compositions of Comparative Examples 3, 5 and 6 contained other polymers (polyvinyl alcohol, sodium carboxymethylcellulose or cellulose nanofibers) instead of the above-mentioned polysaccharide.
The ink receiving layer compositions of Reference Examples 1 and 2 contain an alkylamine-epichlorohydrin polycondensate as a cationic resin, and the ratio of the content of the cationic resin to the total mass of the ink receiving layer composition is And 15% by mass, and further contains a condensate of mannose and galactose as a polysaccharide, and the ratio of the content of the polysaccharide is 0.5% by mass with respect to the total mass of the composition for the ink receiving layer. However, it contains sodium carbonate as a base (Reference Example 1) or contains sodium hydroxide, and the ratio of the content of the base to the total mass of the composition for the ink receiving layer is 1.5% by mass. Was (Reference Example 2).

The ink-receiving layer composition of Comparative Example 4 had too low a viscosity and did not have gravure offset printability. Therefore, in Comparative Example 4, the inkjet recording sheet was not manufactured and evaluated.
The composition for the ink receiving layer of Comparative Example 4 contained another polymer (the same polyvinyl alcohol as in Comparative Example 3) instead of the above-mentioned polysaccharide, and the content thereof was higher than that of Comparative Example 3. There were few.

INDUSTRIAL APPLICATION This invention can be utilized as an inkjet recording sheet, especially an inkjet recording sheet suitable for high-speed printing.

1, 2... Inkjet recording sheet, 11... Base material, 11a... First surface of base material, 11b... Second surface of base material, 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 (5)

An ink-receiving layer composition for forming an ink-receiving layer included in an inkjet recording sheet, comprising:
The composition for the ink receiving layer contains a cationic resin, a polysaccharide and water,
The cationic resin is one or more selected from the group consisting of polyamines and polycondensates of epichlorohydrin,
The polysaccharide is one or more condensates selected from the group consisting of glucose, galactose, mannose and glucuronic acid,
In the composition for the ink receiving layer, the ratio of the content of the cationic resin to the total mass of the composition for the ink receiving layer is 3 to 30% by mass,
In the composition for the ink receiving layer, the ratio of the content of the polysaccharide is 0.3 to 1.3 mass% with respect to the total mass of the composition for the ink receiving layer. The composition for an ink receiving layer according to claim 1, wherein the polysaccharide is one or both of guar gum and xanthan gum. 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 a cationic resin and a polysaccharide,
The cationic resin is one or more selected from the group consisting of polyamines and polycondensates of epichlorohydrin,
The polysaccharide is one or more condensates selected from the group consisting of glucose, galactose, mannose and glucuronic acid,
In the ink receiving layer, the ratio of the content of the cationic resin with respect to the total weight of the ink receiving layer is 70 to 99% by mass,
In the ink-receiving layer, the content of the polysaccharide is 1 to 30 mass% with respect to the total mass of the ink-receiving layer. The inkjet recording sheet according to claim 3, wherein the polysaccharide is one or both of guar gum and xanthan gum. A method for manufacturing an inkjet recording sheet according to claim 3 or 4, wherein
An ink jet printer having a step of applying the composition for an ink receiving layer according to claim 1 or 2 by a gravure offset printing method at a speed of 304.8 m/min or more on at least one surface of a substrate. Recording sheet manufacturing method.

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