JP6497788B2 - Inkjet printing paper - Google Patents

Description

  The present invention relates to ink jet printing paper, and in particular to on-demand ink jet printing paper.

  Printers that use the inkjet method are not limited to printers for terminal PCs, fax machines, or copiers. Inkjet printers that use a so-called on-demand printing method that enables printing of various types of small lots and variable information are also available. It is appearing. Recently, with the expansion of applications due to remarkable progress in high-speed and high-definition equipment, coated paper that has a texture similar to that of general-purpose coated paper (for example, general offset printing paper) There is an increasing demand for imparting inkjet suitability.

  The ink jet method is a method of forming an image by discharging fine ink droplets onto the surface of a transfer object. In recent years, technological progress has been remarkable, the image quality has become extremely high, and the preservability of the image area, which has been a weak point, has been greatly improved by the appearance of pigment-type ink.

  Conventionally, as the ink absorbing layer of ink jet paper, a coating layer having a large pore volume using a pigment having a large specific surface area such as silica, alumina or boehmite as a main component is usually used. However, these inkjet papers are not practical in the field of commercial printing such as on-demand printing because they are not only inferior in texture to general coated paper for printing but also expensive.

  As an ink jet printing paper technology, for example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-091627) discloses a printing paper in which the amount of kaolin, which is a pigment used in a coating layer, is limited to an appropriate value. Yes. However, the ink absorptivity cannot always be satisfied, and as a result, the ink drying property may be insufficient.

JP 2004-091627 A

  An object of the present invention is to provide an ink jet printing paper having a texture similar to that of a general printing paper and being inexpensive and having high ink absorbability and suitable for on-demand printing.

The ink jet printing paper of the present invention is provided with an ink absorbing layer containing a pigment and a binder on at least one surface of a base paper mainly composed of pulp, the binder containing styrene-butadiene latex, ˜80 mass% is light calcium carbonate, the ink absorbing layer does not contain a cationic ink fixing agent, and has a BET specific surface area of 9 m ² / g or more.

  Moreover, it is preferable that the inkjet printing paper of this invention contains 0.01-3.0 mass parts of lubricants with respect to 100 mass parts of said pigments in the said ink absorption layer.

  In the ink jet printing paper of the present invention, the content of the binder in the ink absorbing layer is preferably 3 to 50 parts by mass with respect to 100 parts by mass of the pigment.

  According to the present invention, it is possible to provide an inexpensive inkjet printing paper having a texture comparable to that of general printing coated paper and excellent in ink absorbability. Furthermore, the ink jet printing paper according to the present invention can be printed by a conventional printing machine (for example, an offset printing machine) other than the ink jet printing machine.

(1) Base paper The inkjet printing paper of the present invention is a base paper containing pulp as a main component, for example, a base paper containing 80% by mass or more, 90% by mass or more, and 95% by mass or more of pulp in the base paper. Use it. The pulp used for the base paper of the present invention includes chemical pulp such as LBKP (hardwood bleached kraft pulp), NBKP (softwood bleached kraft pulp), GP (crushed wood pulp), PGW (pressurized groundwood pulp), RMP (refiner mechanical pulp). ), TMP (thermomechanical pulp), CTMP (chemithermomechanical pulp), CMP (chemimechanical pulp), mechanical pulp such as CGP (chemiground pulp), wood pulp such as DIP (deinked pulp) and kenaf, bagasse, Non-wood pulp such as bamboo and cotton. These can be used alone or in admixture at any ratio. For example, a pulp containing 80 to 100 parts by mass of LBKP (hardwood bleached kraft pulp) in the total pulp may be used. In addition, a synthetic fiber can be further blended within a range that does not impair the intended effect of the present invention. From the viewpoint of environmental conservation, ECF (Elemental Chlorine Free) pulp, TCF (Total Chlorine Free) pulp, waste paper pulp, and pulp obtained from planted trees are preferable. Moreover, it is preferable that the pulp which comprises the base paper which concerns on this invention is made into the paper stock which has a suitable beating degree as an inkjet printing paper. Suitable beating degree is, for example, Canadian standard freeness (freeness) (JIS P 8121: 1995 “Pulp Freeness Test Method”), 350 to 650 ml CSF.

  The base paper may contain fillers such as light calcium carbonate, heavy calcium carbonate, talc, clay, kaolin, calcined clay, titanium dioxide, and aluminum hydroxide. The filler content in the base paper is preferably 2 to 20 parts by mass with respect to 100 parts by mass of the dry mass of the pulp. More preferably, it is 3-17 mass parts. More preferably, it is 4-15 mass parts. If it is 2 parts by mass or less, effects such as improvement in whiteness and improvement in opacity may not be obtained. If it exceeds 20 parts by mass, the strength of the paper itself is insufficient, and there is a possibility that it cannot withstand printing and processing and cannot be used substantially.

  In addition to pulp and filler, internal paper strength enhancers such as internal sizing agents and wet paper strength enhancers, bulking agents, yield improvers, drainage improvers, colored dyes, colored pigments, fluorescent brighteners Various auxiliary agents such as a fluorescent decoloring agent and a pitch control agent can be appropriately contained. Various types of internally added sizing agents can be used and are not particularly limited. Examples thereof include reinforced rosin sizing agents, acidic rosin sizing agents, weak acidic rosin sizing agents, AKD, and ASA. As the internally added paper strength enhancer, a conventionally known paper strength enhancer can be used. For example, starch based strength enhancer, polyacrylamide based strength enhancer, polyvinyl alcohol based strength enhancer. It is.

  The method of making the base paper is not particularly limited, and is a long net paper machine, a long net multilayer paper machine, a circular net paper machine, a circular net multilayer paper machine, a long net circular combination paper machine, a twin wire paper machine. It can be manufactured by various devices such as a machine.

A surface size liquid may be applied to the surface of the base paper and the ink absorbing layer. Examples of the surface sizing liquid include, but are not particularly limited to, known water-soluble polymers such as starch, polyvinyl alcohol, and polyacrylamide. Although the basic weight of a base paper is not specifically limited, It is preferable that it is 30-300 g / m < ² >.

  One or more under layers provided by applying a coating liquid mainly composed of a pigment and a binder may be provided between the ink absorption layers of the base paper.

(2) Ink Absorbing Layer In the inkjet printing paper of the present invention, an ink absorbing layer containing a pigment and a styrene-butadiene latex is provided on at least one surface of the base paper. The ink absorption layer is preferably provided so as to be the outermost layer of the inkjet printing paper. As the pigment used in the ink absorbing layer, a known white pigment used in general coated paper for printing can be used. In the present invention, 10 to 80% by mass of the pigment is light calcium carbonate. To do. Preferably it is 20-70 mass%, More preferably, it is 30-60 mass%. When the amount of light calcium carbonate added is less than 10% by mass, the BET specific surface area of the ink absorbing layer may be lowered. If it exceeds 80% by mass, the glossiness of white paper is impaired, and ink jet printing may be inferior in suitability. Furthermore, as pigments other than light calcium carbonate, for example, light calcium carbonate, secondary aggregate of light calcium carbonate, heavy calcium carbonate, kaolin (including clay), calcined clay, zinc oxide, titanium oxide, aluminum hydroxide, Organic pigments such as plastic pigments and plastic pigments, and one or two or more of these are appropriately selected from these according to the purpose. For example, as the pigment of the present invention, 20 to 90% by mass of kaolin and 10 to 80% by mass of light calcium carbonate are used with respect to the entire pigment, for example, 25 to 80% by mass of kaolin and 20 to 20% of light calcium carbonate. 75% by mass is used, preferably 30 to 70% by mass of kaolin and 30 to 70% by mass of light calcium carbonate.

  In the present invention, a styrene butadiene latex is used as the binder used in the ink absorbing layer from the viewpoints of production cost and coating layer strength of the ink absorbing layer. By using 50 to 100% by mass, preferably 60 to 90% by mass, and more preferably 70 to 80% by mass of the binder used for the ink absorbing layer as a styrene-butadiene latex, While maintaining the same level of texture, the coating layer strength can be set to the same level as that of conventional coated paper for printing, and since the cost is low, the manufacturing cost can be kept low. The blending amount of the styrene butadiene latex in the ink absorption layer is not particularly limited, but is preferably 2 to 50 parts by mass, more preferably 4 to 40 parts by mass, and further 4 to 25 parts by mass with respect to 100 parts by mass of the total pigment. More preferred. The binder other than the styrene-butadiene latex used in the ink absorbing layer is not particularly limited, and starches such as oxidized starch, enzyme-modified starch, esterified starch, etherified starch, cationic starch, and amphoteric starch, gelatin, Examples include water-soluble polymers such as casein, soybean protein, and polyvinyl alcohol, and synthetic resins such as vinyl acetate, ethylene vinyl acetate, polyurethane resins, acrylic resins, polyester resins, and polyamide resins. One or more of these can be appropriately selected from these according to the purpose. In particular, a combination of starch and styrene butadiene latex generally used for printing coated paper is preferable from the viewpoint of coating layer strength of the ink absorbing layer and cost reduction.

  Although the compounding quantity of the binder in an ink absorption layer is not specifically limited, It is preferable to set it as 3-50 mass parts with respect to 100 mass parts of all pigments, 5-40 mass parts, Furthermore, 5-20 mass parts, or 5-15. It is more preferable to set it as a mass part. If the blending amount is less than 3 parts by mass, the coating layer may fall off, and if it exceeds 50 parts by mass, the BET specific surface area of the ink absorption layer may be reduced and the ink absorbability may be deteriorated.

In the present invention, the BET specific surface area of the ink absorption layer is set to 9 m ² / g or more. When the BET specific surface area is smaller than 9 m ² / g, the ink absorptivity deteriorates and the ink drying property is inferior. Preferably ^{10 m} 2 / g more ^11m 2 / g or more. The upper limit of the BET specific surface area of the ink absorbing layer is not particularly set, but is preferably 50 m ² / g or less, more preferably 35 m ² / g or less. When it exceeds 50 m ² / g, the coating layer strength of the ink absorbing layer becomes weak, and the general printability such as offset printing may be inferior. Here, the BET specific surface area is a surface area per unit mass determined by the BET method. Further, in the present invention, the BET specific surface area of the ink absorption layer includes the BET specific surface area value (m ² / g) of the inkjet printing paper, the basis weight (g / m ² ) of the on-demand printing paper, and the coating of the ink absorption layer. It calculates | requires by calculation of the following (Formula 1) from quantity (g / m < ² >).

(Formula 1)
BET specific surface area of ink absorbing layer (m ² / g) = BET specific surface area of inkjet printing paper (m ² / g) × basis weight of inkjet (g / m ² ) / coating amount of ink absorbing layer (g / m ² )

  The BET method is a method for measuring the specific surface area of a powder by a gas phase adsorption method, and is a method for obtaining the total surface area, that is, the specific surface area of a 1 g sample from an adsorption isotherm. Usually, nitrogen gas is often used as the adsorbed gas, and the most frequently used method is to measure the amount of adsorption from the change in pressure or volume of the gas to be adsorbed. The most prominent expression for expressing the isotherm of multimolecular adsorption is the Brunauer, Emmett, and Teller equation, called the BET equation, which is widely used for determining the surface area. The adsorption amount is obtained based on the BET equation, and the surface area is obtained by multiplying the area occupied by one adsorbed molecule on the surface. In the present invention, the BET specific surface area of the paper support is treated as being negligibly small.

  Further, the ink absorption layer may contain various auxiliary agents as necessary, for example, lubricants, viscosity modifiers, softeners, gloss imparting agents, water resistance agents, dispersants, flow modifiers, ultraviolet absorbers, stabilizers. An antistatic agent, a crosslinking agent, a sizing agent, a fluorescent brightening agent, a colorant, a pH adjuster, an antifoaming agent, a plasticizer, and a preservative are appropriately blended as necessary. However, in the present invention, the ink absorbing layer does not contain a cationic ink fixing agent. The cationic ink fixing agent is widely used for an ink absorbing layer of a general ink jet recording paper. In the present invention, the ink absorbing layer is formed without using it. In the present invention, the ink absorption layer contains styrene-butadiene latex as a binder and light calcium carbonate as a pigment. Not only does thickening and agglomeration occur and good coating suitability is not obtained, but in some cases the BET specific surface area is lowered, and as a result, ink absorbability may be impaired.

(3) Coating method
The method for coating the ink absorbing layer is not particularly limited, and a commonly used coating apparatus is used. For example, air knife coater, blade coater, gravure coater, rod blade coater, roll coater, reverse roll coater, bar coater, curtain coater, die slot coater, champlex coater, metering blade type size press coater, short dwell coater, spray Various known coating apparatuses such as a coater, a gate roll coater, and a lip coater can be used.

The coating amount of the ink absorbing layer is preferably ² to 40 g / m ² per one side of the base paper. If the absolute dry coating amount is less than 2 g / m ² , it is difficult to obtain a desired ink absorbency, and if it exceeds 40 g / m ² , it is disadvantageous in terms of cost.

(4) Calendar processing
In the present invention, it is preferable to perform a calendering treatment after applying an ink absorbing layer to the base paper and drying it. As the processing apparatus, a normal super calender, gloss calender, shoe nip calender, soft calender, or the like is used. In this case, processing can be performed by appropriately adjusting processing conditions such as the configuration of the pressure device, the number of pressure nips, and temperature conditions. In the present invention, it is preferable to contain a lubricant in the ink absorbing layer in order to prevent stains generated during the calendar process. In the present invention, since the styrene-butadiene latex is contained as a binder in the ink absorption layer, depending on the glass transition temperature, particle size, butadiene ratio, etc. of the styrene-butadiene latex, the surface of the roll is likely to be contaminated during the calendar process. By including a lubricant in the ink absorption layer, this roll stain can be suppressed. The content of the lubricant is preferably 0.005 to 3.0 parts by mass, more preferably 0.008 to 3.0 parts by mass, and 0.01 to 2.7 parts by mass with respect to 100 parts by mass of the pigment. When the lubricant exceeds 3.0 parts by mass, the ink absorbability deteriorates and the ink drying property may be inferior. When the amount is less than 0.005 parts by mass of the lubricant, there is a possibility that calendar fouling occurs and a defect occurs. The lubricant is preferably selected from water-dispersible higher fatty acid salts and derivatives thereof from the viewpoints of ink drying properties and calendar stains. Examples of the water dispersible higher fatty acid salts and derivatives thereof include calcium stearate, ammonium stearate, magnesium stearate, zinc stearate, calcium laurate, barium laurate, calcium ricinoleate, zinc ricinoleate, calcium oleate, and oleic acid. Examples include water dispersions obtained by emulsifying a higher fatty acid salt, such as magnesium, barium oleate, calcium palmitate, or the like, which is hardly soluble or insoluble in water, using a dispersion emulsifier.

  Examples of the present invention will be specifically described below in comparison with comparative examples. This example does not limit the scope of the invention. Further, “parts” and “%” shown in the examples indicate solid mass parts and solid mass% unless otherwise specified.

Example 1
(Preparation of base paper)
Canadian standard freeness 450ml csf hardwood bleached kraft pulp 100 parts, light calcium carbonate (TP-121: manufactured by Okutama Kogyo Co., Ltd.) 10 parts, cationized starch (Neotac 30T: manufactured by Nippon Food Processing Co., Ltd.) 0.3 parts, neutral rosin size Water was added to 0.2 part of the agent (CC167: manufactured by Seiko PMC Co., Ltd.) to prepare a paper stock, and a base paper with a basis weight of 70 g / m ² was prepared using this using a long mesh multi-cylinder paper machine. . Oxidized starch (MS3800: manufactured by Nippon Shokuhin Kako Co., Ltd.) was applied to this base paper with a gate roll coater so that the dry coating amount was 2.5 g / m ² on both sides.

(Preparation of ink absorbing layer coating solution)
Add a dispersant (Aron T-50, manufactured by Toagosei Co., Ltd.) 0.2 part to kaolin (Contour 1500, manufactured by Imeris Co., Ltd.), 40 parts of light calcium carbonate (PC-700, manufactured by Shiroishi Kogyo Co., Ltd.) Then, water was dispersed using a coreless disperser to prepare a pigment slurry. To this pigment slurry, 2 parts of phosphate esterified starch (MS4600, manufactured by Nippon Food Processing Co., Ltd.) and 7 parts of styrene-butadiene latex (PA0372, Nippon A & L Co., Ltd.) are added as a binder, and then a higher fatty acid salt as a lubricant. 2.5 parts of an aqueous dispersion of calcium stearate (DEF-963TF, manufactured by Nisshin Chemical Laboratory Co., Ltd.) and water were added to prepare an ink absorbing layer coating liquid having a solid content concentration of 50%.

(Preparation of inkjet printing paper)
The ink absorbing layer coating solution was applied to both sides of the base paper obtained above using a blade coater and dried so that the dry coating amount per side of the base paper was 10 g / m ² . Thereafter, a calendar process was performed to prepare an inkjet printing paper having a basis weight of 92.5 g / m ² .

(Example 2)
In Example 1, 40 parts of light calcium carbonate (PC-700, manufactured by Shiroishi Kogyo Co., Ltd.) was changed to 40 parts of secondary agglomerated light calcium carbonate (TP121SA, manufactured by Okutama Kogyo Co., Ltd.). Inkjet printing paper was prepared.

(Example 3)
Example 1 except that the amount of kaolin (Contour 1500, manufactured by Imeris Corporation) was 30 parts and the amount of light calcium carbonate (PC-700, manufactured by Shiroishi Kogyo Co.) was 70 parts. Inkjet printing paper was prepared in the same manner.

Example 4
Example 1 is the same as Example 1 except that the addition amount of kaolin (Contour 1500, manufactured by Imeris Corp.) is 75 parts and the addition amount of light calcium carbonate (PC-700, manufactured by Shiroishi Kogyo Co., Ltd.) is 25 parts. Inkjet printing paper was prepared in the same manner.

(Example 5)
Example 1 is the same as Example 1 except that the amount of kaolin (Contour 1500, manufactured by Imeris Corp.) is 80 parts and the amount of light calcium carbonate (PC-700, manufactured by Shiraishi Kogyo Co.) is 20 parts. Inkjet printing paper was prepared in the same manner.

(Example 6)
An ink jet printing paper was prepared in the same manner as in Example 1 except that the amount of lubricant added was 0.01 parts in Example 1.

(Example 7)
An ink jet printing paper was prepared in the same manner as in Example 1 except that the amount of lubricant added was 3.0 parts in Example 1.

(Comparative Example 1)
In Example 1, except that 40 parts of light calcium carbonate (PC-700, manufactured by Shiraishi Kogyo Co., Ltd.) in the ink absorbing layer was changed to 40 parts of heavy calcium carbonate (Carbillax, manufactured by Imeris Co., Ltd.), the same as in Example 1. Inkjet printing paper was prepared.

(Comparative Example 2)
Inkjet printing paper was prepared in the same manner as in Example 1 except that only 100 parts of heavy calcium carbonate (Carbillax, manufactured by Imeris) was used as the pigment of the ink absorbing layer.

  The obtained inkjet printing paper was evaluated by the following method. The obtained results are shown in Table 1.

(1) Evaluation of ink drying properties
Solid printing was performed using the following ink jet printer, PPC paper was stacked after printing, and the transfer amount of ink was visually measured as follows by rubbing by hand.

Printer: PX-101A (manufactured by EPSON)
A: There is no transfer and it can be used practically.
○: The transfer amount is small and practical.
(Triangle | delta): Although there are many transcription | transfer amounts, it is practical if it is a pattern with light printing.
X: The transfer amount is large and impractical.

(2) BET specific surface area of the ink absorbing layer
After the obtained inkjet printing paper is cut into a plurality of small pieces having a size of about 3 mm × 3 mm, about 1 g is vacuum degassed at 105 ° C. and 10 Pa or less for 12 hours, and then a pore distribution measuring device by nitrogen adsorption method The BET specific surface area value was measured using (Tristar II3020: manufactured by Shimadzu Corporation). Further, the BET specific surface area value of the ink absorbing layer of the present invention is obtained by the following calculation (Equation 1).

(Equation 1)
BET specific surface area of ink absorbing layer (m ² / g) = BET specific surface area of inkjet printing paper (m ² / g) × basis weight of inkjet printing paper (g / m ² ) / coating amount of ink absorbing layer (g / M ² )

As is clear from Table 1, the ink-jet printing paper obtained in Examples 1 to 7 had better ink drying properties than Comparative Examples 1 and 2. From this, it is thought that the ink absorption layer of the inkjet printing paper obtained in Examples 1-7 has high ink absorptivity. On the other hand, the ink-jet printing paper obtained in Comparative Examples 1 and 2 resulted in poor ink drying properties. It is considered that the BET specific surface area of the ink absorbing layer was less than 9 m ² / g, and the ink absorptivity could not be satisfied.

Claims (4)

Only one layer of an ink absorbing layer containing a pigment and a binder is provided on at least one surface of a base paper containing pulp as a main component, the binder contains a styrene-butadiene latex, and the pigment is a light weight of 40 to 70% by mass. It consists of calcium carbonate and 30-60% by weight kaolin , and the pigment does not contain silica and heavy calcium carbonate, the ink absorption layer does not contain a cationic ink fixing agent, and the BET specific surface area is 9 m ² / g. This is the inkjet printing paper. Only one layer of an ink absorbing layer containing a pigment and a binder is provided on at least one surface of a base paper containing pulp as a main component, the binder contains a styrene-butadiene latex, and the pigment is 40 to 70% by mass. An ink jet printing paper comprising calcium carbonate and 30 to 60 % by mass of kaolin, wherein the ink absorbing layer does not contain a cationic ink fixing agent, and has a BET specific surface area of 9 m ² / g or more.   The inkjet printing paper according to claim 1 or 2, wherein the ink absorbing layer contains 0.005 to 3.0 parts by mass of a lubricant with respect to 100 parts by mass of the pigment.   The inkjet printing paper according to any one of claims 1 to 3, wherein the content of the binder in the ink absorbing layer is 3 to 50 parts by mass with respect to 100 parts by mass of the pigment.