JP2001072413A - Precipitated calcium carbonate and ink-jet recording paper using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ink-jet recording paper, having excellent recording characteristics such as ink absorption, fixation, etc., and high gloss. SOLUTION: Precipitated calcium carbonate which is subjected to dispersion treatment with a cationic dispersant and has >=5 mV ζpotential and <=0.9 μm model pore diameter is used as a pigment for a coated layer of ink-jet recording paper. To be concrete, a coated layer containing precipitated calcium carbonate and a binder is formed on a base paper. The cationic dispersant is preferably a cationic compound or a cationic resin having <10,000 molecular weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to light calcium carbonate and an ink jet recording paper using the same.

[0002]

2. Description of the Related Art Since high ink absorption is required for ink jet recording paper, coated paper having a coating layer formed by coating a porous and high surface area pigment is used. . As such pigments, synthetic silica, alumina and the like are generally used, but various kinds of ink jet recording papers using colloidal calcium carbonate which is inexpensive and have a small particle diameter have been developed.

However, ordinary calcium carbonate is inferior to silica or the like in ink-jet recording characteristics such as ink absorbency and ink fixability, and various proposals have been made to improve such characteristics. For example, Japanese Patent Publication No. 4-60033, Japanese Patent Publication 4-6
[0034] JP-A No. 8-198623 and JP-A-8-198623 propose a device using calcium carbonate having a specific surface area in a specific range or a specific porous structure in order to enhance the ink absorption. Further, in order to enhance the ink fixing property and water resistance, it has been proposed to modify calcium carbonate with a cation agent or to incorporate a cation agent into the coating liquid for the recording layer (Japanese Patent Application Laid-Open No. 10-129113, JP-A-11-20301).

On the other hand, high-quality ink-jet recording paper used for printing photographic images and the like is required to have high gloss. However, in general, silica-based paper has a very small silica particle size, so that aggregation is difficult. Since it is strong and hard to be highly smooth, sufficient gloss cannot be obtained as it is. Therefore, after forming a coating layer, high gloss is obtained by performing a cast coat (mirror finish) or a super calender treatment.

[0005]

In the case of calcium carbonate, it is possible to increase the glossiness by increasing the proportion of the pigment in the coating layer. When using fine calcium carbonate, especially colloidal calcium carbonate having an average particle diameter of 0.10 μm or less,
Since such pigments have poor dispersibility, there has been a problem that when added to a coating liquid, the surface becomes rough and gloss does not increase. In addition, since the concentration of light calcium carbonate (PCC) slurry is low, the color concentration in the coating solution has to be lowered, resulting in low productivity.

On the other hand, as a method of increasing the gloss, there is a dispersion treatment of a pigment. However, since a dispersant is generally an anionic dispersant, there is a problem that the ink absorption capacity is reduced when dispersed calcium carbonate is used. there were. Further, when a cationic agent is contained in the coating liquid in order to enhance the ink absorbing ability, there is a problem that color loss occurs if the cationic agent is not well distributed.

Accordingly, an object of the present invention is to provide a cationic calcium carbonate slurry which contains a relatively large amount of fine calcium carbonate and is easy to handle in subsequent applications. Another object of the present invention is to provide an ink jet recording paper which is excellent in recording characteristics such as ink absorbency and fixability and has high gloss.

[0008]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies and found that zeta (Zeta) was obtained by first dispersing fine calcium carbonate with a cationic agent functioning as a dispersant. ii) A calcium carbonate slurry having an electric potential of +5 mV or more and usable for various applications and easy to handle can be obtained. When such slurry calcium carbonate is mixed with a binder, a relatively large amount of pigment and cationic agent can be obtained. A coating liquid uniformly and easily dispersed in a binder can be obtained, and a recording layer formed by applying such a coating liquid has excellent ink absorbency, fixability, and high gloss. Heading, the present invention has been completed.

That is, the light calcium carbonate of the present invention is a light calcium carbonate dispersed with a cationic dispersant, and has a zeta potential of +5 mV or more and a most frequent pore diameter of 0.1 mV.
It is 9 μm or less.

The zeta potential (electrokinetic potential) means the potential difference between the fixed layer on the solid surface and the liquid (here, water). The higher this value is, the larger the charge amount of the fixed layer is. Further, in this specification, the most frequent pore diameter is a value measured by a mercury intrusion-type pore distribution measuring device, and the more frequent pore diameter can be reduced as the degree of dispersion is increased.

Such calcium carbonate can be used as a filler for an inner paper or a pigment for a coated paper, and can be particularly suitably used as a filler or a pigment for an ink jet recording paper.

The light calcium carbonate of the present invention is a light calcium carbonate having a zeta potential of +5 mV or more, a most frequent pore diameter of 0.9 μm or less, and a BET specific surface area of 30 m, which has been subjected to a dispersion treatment with a cationic dispersant. ² / g or more.

[0013] In the light calcium carbonate of the present invention, the cationic agent is preferably a cationic compound or a cationic resin having a molecular weight of less than 100,000.

Further, the ink jet recording paper of the present invention is
It has a layer formed by coating a base paper with a coating liquid containing light calcium carbonate dispersed with a cationic dispersant and a binder.

In a preferred embodiment, the light calcium carbonate is a light calcium carbonate having a ζ potential of +5 mV or more and a most frequent pore diameter of 0.9 μm or less. In a more preferred embodiment, the light calcium carbonate has a BET specific surface area of 30 m ² / g or more. The cationic dispersant is a cationic compound or a cationic resin having a molecular weight of less than 100,000.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The light calcium carbonate of the present invention is a light calcium carbonate dispersed with a cationic dispersant,
ζ The potential is +5 mV or more and the most frequent pore diameter is 0.9 μm or less.

In the present invention, light calcium carbonate (PCC) before the dispersion treatment is obtained by subjecting the slurry after the carbonation step to a concentration treatment, a dehydration treatment after the concentration treatment, or a dehydration treatment.
Either a concentrated liquid or a dehydrated cake or a dried and powdered one may be used. Particularly, a concentrated liquid or a dehydrated cake is suitable.

As the PCC as a raw material, one produced by a known method, such as baking limestone and adding water to the lime milk obtained by blowing carbon dioxide gas, can be used.
In particular, colloidal calcium carbonate having an SEM particle diameter of 0.10 μm or less is preferable. In order to obtain such colloidal calcium carbonate, a method of performing the carbonation step in a plurality of times, a soluble metal salt, a polyhydric alcohol, aluminum sulfate, magnesium sulfate, sulfuric acid, zinc sulfate, zinc chloride in the carbonation step, A method of adding additives such as sodium hexametaphosphate and bisphosphonic acid, a method of aging after the reaction, and the like can be appropriately combined and used.

The concentration treatment of the slurry after the carbonation is carried out using a usual concentration means, for example, a centrifugal dehydrator, a sedimentation concentrator and the like. Examples of the centrifugal dehydrator include a decanter and a screw decanter.

The dehydration treatment is carried out by using ordinary dehydration means, for example, a pressurized dehydrator such as a filter press, a belt press or a tube press; a vacuum drum dehydrator such as an Oliver filter; a centrifugal dehydrator such as a decanter; ,
For example, it is performed by using a means for granulating into a required shape at the same time as dehydration such as a belt press or a granulating roller.

When a PCC concentrate or dehydrated cake is used, the solid content concentration of PCC is preferably 20 to 85% by weight, more preferably 25 to 80% by weight, more preferably 25 to 80% by weight in terms of dry weight, although it varies depending on the use. Preferably 30 to 7
5% by weight.

In the present invention, a cationic dispersant is used for the dispersion treatment. The cationic dispersant means a compound or resin having a positive surface potential and having a function as a dispersant.

Specific examples of the cationic dispersant include 1) polyalkylene polyamines such as polyethylene polyamine and polypropylene polyamine or derivatives thereof, 2) secondary amine group, tertiary amine group and quaternary amine group. Acrylic resin having a quaternary ammonium group, 3) polyvinylamine, polyvinylamidines, 4) dicyandiamide-formalin polycondensate, dicyandiamide-diethylenetriamine polycondensate, dicyanamide resins such as copolymers of polyalkylenepolyamines and dicyandiamide, 5 ) Epichlorohydrin-dimethylamine addition polymer, 6) diallyldimethylammonium chloride,
Polymers such as dimethyldiammonium chloride and dimethylallylammonium chloride or copolymers with sulfonyl or acrylamide; 7) Copolymers of quaternary salt of dialkylaminoethyl (meth) acrylate such as dimethyldiaminoethyl acrylate sulfate or acrylamide 8) Polymer of allylamine salt,
9) A cationic resin or a cationic compound such as an acrylamide-diacrylamine salt copolymer is used. Of these, diallyldimethylammonium chloride,
A polymer composed of a monomer such as dimethyldiammonium chloride and dimethyldiaminoethyl acrylate sulfate, or a copolymer of the above monomer and another monomer such as acrylamide is preferred.

These cationic compounds or resins have a molecular weight of 100 to function as a dispersant.
0 or more, preferably 10000 or more. On the other hand, if the molecular weight is 100,000 or more, it becomes blocked and the viscosity of the slurry increases, and when a coating liquid is prepared using this, coating becomes difficult. Therefore, the molecular weight of the cationic dispersant is preferably less than 100,000.

The amount of the cationic dispersant is preferably from 0.1 to 50% by weight, more preferably from 0.5 to 50% by weight of the pigment in terms of dry weight.

The dispersion can be carried out using a conventional apparatus using a high-speed stirrer such as a Coreless mixer or a homogenizer or a medium mill such as a sand mill, an attritor, a pin mill, or a ball mill. When a medium mill is used to increase the number of dispersions, it is preferable to increase the filling rate.

Calcium carbonate thus dispersed with a cationic dispersant has a zeta potential of +5 mv or more. Thereby, when used for a material containing an anionic component, it reacts with or binds to the anionic component, thereby improving the properties of the material.

The higher the degree of dispersion, the larger the specific surface area and the smaller the most frequent pore size. The light calcium carbonate of the present invention has the most frequent pore size of 0.9 μm or less. The specific surface area of light calcium carbonate (BE
T) is preferably 30 m ² / g or more, more preferably 40 m ² / g, and still more preferably 50 m ² / g.

By using a pigment having a specific surface area and a most frequent pore diameter in the above-described ranges, high ink absorbency can be maintained when used as a pigment for ink jet recording paper.

Next, the ink jet recording paper of the present invention using such a calcium carbonate slurry will be described.

Ink-jet recording paper containing an inorganic pigment in a coating layer is produced and sold as a higher grade of clear-coat prescription ink-jet recording paper. The inkjet recording paper containing an inorganic pigment in the coating layer has one or more recording layers, an ink absorbing layer, and a coating layer called a gloss layer, and the gloss layer is cast-finished. There are some, but the calcium carbonate slurry of the present invention can be applied to any type, and can be added as a pigment to at least one of these recording layer, ink absorbing layer and gloss layer.

As the base material of the ink jet recording paper of the present invention, a paper base material such as an acidic paper and a neutral paper, a synthetic paper, a resin sheet and the like, which are used for general coated paper, are appropriately used.

The coating layer mainly comprises a pigment and a binder, and uses calcium carbonate dispersed with the above-mentioned cationic dispersant as the pigment. In this case, a colloidal calcium carbonate having a most frequent pore diameter of 0.9 μm or less and a specific surface area (BET) of 30 m ² / g or more is particularly preferable.

As the pigment for the coating layer, in addition to such light calcium carbonate, inorganic pigments such as silica (amorphous silica, colloidal silica, amorphous silica) and alumina (Al ₂ O ₃ ) may be used in combination. it can. Such a pigment other than calcium carbonate may be added at the time of preparing the coating liquid, but may also be added at the step of producing light calcium carbonate.

Examples of the binder include proteins such as casein, soy protein, and synthetic protein; various starches such as starch and oxidized starch; modified polyvinyl alcohols such as polyvinyl alcohol, cation-modified polyvinyl alcohol, and silyl-modified polyvinyl alcohol;
Water-soluble adhesives such as cellulose derivatives such as carboxymethylcellulose and methylcellulose, conjugated diene-based polymer latex such as styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, acrylic polymer latex, ethylene-vinyl acetate copolymer And water-dispersible adhesives such as vinyl polymer latex, etc. can be used alone or in combination.

The amount of the binder varies depending on the use of the coating layer, but is usually 5 to 100% by weight, preferably 10 to 95% by weight, based on 100% by weight of the pigment. Further, the coating liquid used in the present invention may further contain auxiliary agents such as a thickener, a defoaming agent, a coloring agent, an antistatic agent and a preservative which are generally used in the production of coated paper. .

In the ink jet recording paper of the present invention, the coating layer can be formed by mixing calcium carbonate slurried by a dispersion treatment with a binder, coating and drying.

The coating liquid is usually 0.05 to 30 g / m ² ,
The coating is preferably performed at a solid content of 0.1 to ²⁰ g / m ² , more preferably 0.2 to 15 g / m ² . The coating liquid is a blade coater, air knife coater, roll coater, brush coater, champlex coater, bar coater, gravure coater, gate roll,
It is coated by a conventional coating device such as a size press and dried. When a gloss layer is provided as a coating layer in addition to the recording layer, a coating solution for the recording layer is applied and dried, and then a coating solution for the gloss layer is applied and dried.

If necessary, after the coating liquid has dried,
The surface of the obtained recording layer or gloss layer may be subjected to a smoothing treatment such as super calendering or brushing or a cast finish.

The ink-jet recording paper of the present invention reacts with the anionic dispersant in the ink by using light calcium carbonate dispersed with a cationic agent as the pigment of the coating layer on the surface, thereby forming a dye. Can be prevented from penetrating into the inside, and the water resistance of the recorded image can be increased. Further, the coating layer can be easily prepared, and a glossy coating layer having excellent ink absorbency can be obtained.

[0042]

The present invention will be described in more detail with reference to examples.

In the following examples, the zeta potential is
Using a PEN KEN LAZER ZEE model 501, the BET specific surface area was measured using a Flow Sorb II model manufactured by Shimadzu Corporation. pore II 9220). The median diameter is a 50% particle diameter measured by a laser particle size distribution analyzer (LA-920, manufactured by Horiba, Ltd.).

Example 1 A 100-liter container was charged with 60 liters of tap water from Mizuho-cho, Nishitama-gun, Tokyo, and the temperature was adjusted to 60 ° C, followed by stirring with a stirrer at a peripheral speed of 2.6 m / s (500 rpm). While adding 6 kg of calcium oxide, continue stirring,
30 minutes after charging, the mixture was sieved with a 325 mesh sieve, and 10
An aqueous calcium hydroxide slurry of 0 g / l was obtained.

30 liters of this slurry was charged into a 50-liter cylindrical semi-batch reactor equipped with a stirrer.
After adjusting to 20 ° C., the stirring peripheral speed is 10 m / s (2550 rp).
m), while stirring with a sulfuric acid band 8% solution (AL ₂ (S
_{O 4) 3 · 18H 2 O} ) was added 3% per dry weight of calcium hydroxide, then, 10 NL carbon dioxide-containing gas at 100 volume% in terms of per calcium hydroxide 1kg
The reaction was continued until the carbonation rate reached 100% to obtain a PCC aqueous suspension. This is 325mesh
Calcium carbonate (PCC) obtained by filtration through a sieve has a pore volume of 2.1 cc / g, a most frequent pore diameter of 1.3 μm, a median diameter of 3.5 μm, a SEM particle diameter of 0.08 μm, a zeta potential of +1 mV, and a BET ratio. The calcite-type colloid particles had a surface area of 56 m ² / g.

The obtained aqueous PCC suspension was dewatered by filter press to obtain a dehydrated cake having a solid content of 55% by weight.

Water and a cationic dispersant were put into a Cores mixer (6400 rpm, stirring speed 25 m / s) so as to have a solid content of 45 to 46%, and the dehydrated cake obtained above was put into this, The primary dispersion was performed for 20 minutes.
The cationic dispersant is a diallyl dimethyl ammonium chloride polymer having an average molecular weight of 10,000 (hereinafter referred to as cation a).
) Was used at a ratio of 2% as [dispersant solids / PCC solids]. Next, a sand mill (Dynomill KDL-) using glass beads (diameter 1 to 1.4 mm) at a filling rate of 85%.
PILOT: Shinmaru Enterprises) with a peripheral speed of 1
Secondary dispersion was performed at 4 m / s and a liquid flow rate of 0.1 L / min to obtain an aqueous slurry.

The viscosity of the obtained calcium carbonate slurry is
The zeta potential and the median diameter were measured with a Brookfield viscometer (25 ° C., 60 rpm). The BET specific surface area, the pore volume, and the most frequent pore diameter were measured for a sample obtained by drying the aqueous slurry at 105 ° C. for 24 hours and pulverizing with a coffee mill for 1 minute. The results are shown in Tables 1 and 2.

Example 2 Colloidal calcium carbonate (BET) produced in the same manner as in Example 1
Using a dehydrated cake containing calcite-type colloid particles having a specific surface area of 56 m ² / g, instead of cation a, another cationic dispersant (copolymer of diallyldimethylammonium chloride having an average molecular weight of 20,000 and acrylamide; b) was used as a dispersant, and an aqueous slurry was produced in the same manner as in Example 1 except for the above. The viscosity and viscosity of this slurry were the same as in Example 1.
The zeta potential and median diameter were measured. The results are shown in Table 1. The BET specific surface area, the pore volume, and the most frequent pore diameter were measured for the sample obtained by pulverizing the aqueous slurry in the same manner as in Example 1. Table 2 shows the results.

Example 3 As an additive in the carbonation step of a calcium hydroxide slurry, aluminum sulfate (P
An aqueous slurry (slurry 4) was produced in the same manner as in Example 1, except that AC) was added in an amount of 3% by weight based on the dry weight of calcium hydroxide. The viscosity, zeta potential and median diameter of this slurry were measured in the same manner as in Example 1. The results are shown in Table 1. The BET specific surface area, the pore volume, and the most frequent pore diameter were measured for the sample obtained by pulverizing the aqueous slurry in the same manner as in Example 1. Table 2 shows the results.

Example 4 In the step of carbonating a calcium hydroxide slurry, when the degree of carbonation was 80%, an aqueous sodium silicate solution (for industrial use No. 3) was added at 10% by weight based on the dry weight of calcium hydroxide. The reaction was performed until the concentration reached 100% to produce a colloidal calcium carbonate. An aqueous calcium carbonate slurry was produced in the same manner as in Example 1 except that this colloidal calcium carbonate was used. This slurry was also used in Example 1.
The viscosity, the zeta potential and the median diameter were measured in the same manner as described above. The results are shown in Table 1. The BET specific surface area, the pore volume, and the most frequent pore diameter were measured for the sample obtained by pulverizing the aqueous slurry in the same manner as in Example 1. Table 2 shows the results.

Comparative Example 1 The dehydrated calcium carbonate cake obtained in Example 1 was slurried with a Cores mixer by adding water to a solid concentration of 45 to 46%. No dispersant was used. The viscosity, zeta potential and median diameter of these slurries were measured in the same manner as in Example 1. The results are shown in Table 1. The BET specific surface area, the pore volume, and the most frequent pore diameter were measured for the sample obtained by pulverizing the aqueous slurry in the same manner as in Example 1. Table 2 shows the results.

Comparative Example 2 The calcium carbonate dehydrated cake obtained in Example 1 was slurried by adding water so as to have a solid content concentration of 45 to 46% using a Cores mixer, and then subjected to dispersion treatment using a sand mill. However, the viscosity of the slurry increased to 10,000 cP or more. This slurry also has viscosity,
Table 1 shows the results of measuring the zeta potential and the median diameter. The BET specific surface area, the pore volume, and the most frequent pore diameter were measured for the sample obtained by pulverizing the aqueous slurry in the same manner as in Example 1. Table 2 shows the results.

Comparative Example 3 The dehydrated calcium carbonate cake obtained in Example 1 was dispersed in the same manner as in Example 1 except that an anionic dispersant (sodium polyacrylate having an average molecular weight of 15,000) was used. Manufactured. Table 1 shows the results of measurement of the viscosity, zeta potential, and median diameter of this slurry. In addition, for the sample obtained by pulverizing the aqueous slurry in the same manner as in Example 1, the BET specific surface area,
The pore volume and the most frequent pore size were measured. Table 2 shows the results.

Comparative Example 4 Instead of calcium carbonate, synthetic silica (manufactured by Mizusawa Chemical,
Mizukasil P-78A, a BET specific surface area of 400 m ² / g) was dispersed in water to a concentration of 30% by weight using a Cores mixer to obtain a slurry.

COMPARATIVE EXAMPLE 5 Instead of cation a, a calcium dispersing agent (average molecular weight: 5) was prepared in the same manner as in Example 1 except that cation a was used.
Using a 100,000 copolymer of diallyldimethylammonium chloride and acrylamide (hereinafter referred to as cation c), a slurry was formed with a Cores mixer. Blocks were formed locally in the initial stage of dispersion, but the blocks were resolved as dispersion proceeded. However, since the molecular weight of the cationic dispersant is high, the slurry viscosity is 10,000 cP.
It thickened more than this. Table 1 shows the results of measuring the viscosity and zeta potential of this slurry.

[0057]

[Table 1]

[0058]

[Table 2]

As can be seen from the results in Tables 1 and 2, by dispersing using a dispersant, all of the pore volume, the most frequent pore diameter and the median diameter can be made smaller than the light calcium carbonate as the raw material. In addition, the BET specific surface area could be increased. In addition, calcium carbonate having a high zeta potential was obtained by dispersing with a cationic dispersant.

Application Examples 1 to 4 100% by weight of each slurry obtained in Examples 1 to 4
And polyvinyl alcohol (Kuraray PV-117) 1
A coating solution having a solid content of 20% by weight was prepared by adding 5% by weight, and hand-coated on a commercial high-quality paper with a coating rod, followed by drying at 105 ° C. for 2 minutes. Thereafter, humidity control was performed for 24 hours, and calender treatment (linear pressure: 100 kg / cm, treatment temperature: 55 ° C., treatment speed: 8 m / min, number of nips: once) was performed to produce an inkjet recording paper.

Application Example 5 50% by weight of the aqueous slurry obtained in Example 2 and silica 5
0% by weight of polyvinyl alcohol (Kuraray PV-11)
7) 15% by weight and 1% by weight of cation a were added to prepare a coating solution having a solid content concentration of 20% by weight, and the other conditions were the same as in Examples 1 to 4 to produce inkjet recording paper.

Application Examples of Comparative Examples 1 to 4 (Comparative Application Examples 1 to 4)
4) 100% by weight of the slurry obtained in each of Comparative Examples 1 to 4
And polyvinyl alcohol (Kuraray PV-117) 1
5% by weight and 2% by weight of cation a were added, and the other conditions were the same as in Examples 1 to 4 to produce an inkjet recording paper. Table 3 shows the mixing ratio of each coating liquid in the application examples and the comparative application examples.

[0063]

[Table 3]

The ink-jet papers manufactured in the above-mentioned application examples 1 to 6 and comparative application examples 1 to 4 were printed using an ink-jet printer (manufactured by EPSON, PM-750C), and were suitable for ink-jet recording (solid uniformity, ink uniformity). Drying property, image quality, print density) were evaluated. The glossiness of the blank portion and the printed portion was evaluated.

The evaluation method for each item is as follows. Solid uniformity: Observation of printing unevenness was visually observed for a solid printing portion of a mixture of two colors of cyan and magenta, and O was observed when no printing unevenness was observed, Δ when almost no printing unevenness was observed, and A marked case was marked as x. Ink drying property: When the solid printed portion was touched with a finger immediately after printing, it was evaluated as ○ when no stain was found, Δ when slightly stained, and X when stained. Image quality: Bleeding of the ink at the boundary between the printed part and the non-printed part was visually observed.
If it was slightly recognized, then ×
And Glossiness of white paper part and printed part: 75 ° gloss of white part and solid black part was measured according to JIS-P8142. Table 4 shows the results.

[0066]

[Table 4]

As is evident from the results shown in Table 4, all of the ink jet recording papers prepared using the calcium carbonate slurries obtained in Examples 1 to 4 provided good or practical level recording suitability. In particular, when calcium carbonate produced by adding sodium silicate in the carbonation step is used (Application Example 4) or when used in combination with silica (Application Example 5), silica is used for all recording aptitudes (Application Example 5). It exhibited excellent characteristics not inferior to Comparative Application Example 4).

As for the gloss, both the white portion and the printed portion exhibited excellent gloss as compared with the case using only silica (Comparative Application Example 4), and particularly exhibited excellent gloss when only calcium carbonate was used. . On the other hand, in the case of inkjet recording paper prepared using a slurry dispersed without using a dispersant or using an anionic dispersant, the glossiness was excellent, but the recording suitability was not at a practical level. .

When light calcium carbonate synthesized by using aluminum sulfate and PAC together is used as an additive for synthesizing light calcium carbonate (Application Example 3),
Excellent ink jet characteristics were obtained as compared with the case of using aluminum sulfate alone.

[0070]

According to the ink jet recording paper of the present invention, a coating liquid obtained by mixing a binder and calcium carbonate obtained by dispersing a coating layer such as a recording layer with a cationic dispersant is applied. Due to the formation, the pigment and the cationic agent are uniformly dispersed in the recording layer. Therefore, the ink jet recording paper of the present invention is excellent in ink jet recording characteristics such as excellent ink absorbability and no ink bleeding or color loss. Further, when colloidal calcium carbonate is used as the pigment, the ink absorbency is further improved, and the glossiness can be improved. Therefore, there is no need to separately provide a gloss layer, and reduction in production cost and improvement in productivity can be achieved.

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Claims (7)

[Claims] 1. Light calcium carbonate dispersed with a cationic dispersant, having a ζ potential of +5 mV or more and a most frequent pore diameter of 0.9 μm or less. 2. The light calcium carbonate according to claim 1, wherein the light calcium carbonate has a BET specific surface area of 30 m ² / g or more. 3. The light calcium carbonate according to claim 1, wherein the cationic dispersant is a cationic compound or a cationic resin having a molecular weight of less than 100,000. 4. An ink jet recording paper having a layer formed by coating a base paper with a coating liquid containing light calcium carbonate dispersed with a cationic dispersant and a binder. 5. The light calcium carbonate has a ζ potential of +5.
5. The ink jet recording paper according to claim 4, which is a light calcium carbonate having a mV or more and a most frequent pore diameter of 0.9 [mu] m or less. 6. The ink jet recording paper according to claim 4, wherein the light calcium carbonate is a light calcium carbonate having a BET specific surface area of 30 m ² / g or more. 7. The ink jet recording paper according to claim 4, wherein said cationic dispersant is a cationic compound or a cationic resin having a molecular weight of less than 100,000.