JPH05139023A - Ink jet recording paper - Google Patents

Abstract

PURPOSE:To provide an improved water-soluble ink jet recording paper with properties such as an excellent color development or dot shape, etc. CONSTITUTION:On one surface of a base paper of which the major component is a broad leaf tree bleached pulp, and of which the Oken-(developed by Laboratory of Oji Paper Making Co.)-type smoothness is 21 sec, the density of 0.70g/cm<3>, the areal weight is 74g/m<2>, a paint consisting of sorpuscle silica with an oil absorbency of 220ml/100g and polyvinyl alcohol is applied and dried, and supercalender treatment is applied to manufacture the title ink jet recording paper. The density of an ink acceptable coat layer is 0.72g/cm<3>, the Oken-type smoothness of the ink jet recording paper is 33 sec, the opacity is 83%, and the bursting strength is 1.7kg/cm<2>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material, and more particularly, to an improved water-based ink jet recording paper having excellent color-developing characteristics and characteristics such as dot shape.

[0002]

2. Description of the Related Art The performance of ink jet printers using water-based inks, especially the improvement in printing speed, resolution, saturation, etc., enables high-speed absorption even on recording materials.
Higher characteristics such as high absorption capacity and regular ink bleeding are required, and so-called coated paper having an ink-receptive coating layer on the surface has been developed.

As a conventional ink jet recording paper,
A paper using an absorbent material such as a non-sized paper (for example, Japanese Examined Patent Publication No. 62-55996), or a substantially non-sized paper provided with an absorptive coating layer containing silica (JP-A-52-52).
-53012), a high-size paper provided with an absorptive coating layer containing silica (JP-A-61-68286), an absorptive coating layer containing silica as a main component on a substrate such as a non-absorptive plastic film. Provided with (Japanese Patent Laid-Open No. 63-115
779) and the like have been proposed.

For an ink jet recording paper having an ink receptive coating layer on its surface, various methods are used to express the ink absorbency and ink absorbing capacity of the paper, which is expressed by the ratio of air permeability and basis weight. Method (JP-A 63-1582), Stoeckigt sizing degree and Beck smoothness (JP-A 61-16
885) and a method of expressing water absorption by the Brist method (Japanese Patent Laid-Open No. 60-122188).

When the method of measuring the ink absorptivity which has been conventionally used for ink jet recording paper is used, the absorptivity of the ink is varied, and it is not sufficient for those requiring a delicate ink absorption capacity.

The ink jet recording paper coated with a commonly used fine particle silica pigment is usually 10
It was necessary to provide an ink receiving layer of g / m ² or more. The ink-receiving layer containing silica as a main component is 10
If it is less than g / m ² , in many cases, the ink absorption capacity will be insufficient, and the image will run out, color fringing will occur, the image will be blurred, the drying will be slow, and the ink will adhere to the roll and become dirty. Occur. However,
When the ink receiving layer of 10 g / m ² or more is provided, the coating layer is thick and the adhesion to paper is weakened, which often causes a problem such as clogging of the head nozzle, and the cost is high. There is a problem.

[0007]

DISCLOSURE OF THE INVENTION As a result of intensive studies made by the present inventors in view of the present situation, the formation of the base paper is improved by specifying the burst strength of the ink jet recording paper, and the uniform ink absorbency is obtained. Therefore, the present invention has been completed by finding that unevenness of the paper after printing is eliminated and excellent printing can be obtained.

Therefore, an object of the present invention is to maintain a high smoothness while the ink-receptive coating layer has a low coating amount and has a good ink absorbency without bleeding, and has a uniform ink absorbency and a high resolution. Another object of the present invention is to provide an excellent inkjet recording paper having characteristics such as clear color development.

[0009]

The present invention comprises cellulose pulp as a main component, and has a smoothness of 5 to 60 seconds by Oken type and a density of 0.6.
An oil absorption of 1 on at least one surface of a base paper composed of 0 to 0.75 g / cm ³ and a basis weight of 20 to 200 g / m ^2.
50 to 350 ml / 100 g of fine particle synthetic silicic acid and a water-soluble polymer adhesive
10 g / m ² , the ink-receptive coating layer has a density of 0.70 to 0.80 g / cm ³ , and the inkjet recording paper has an Oken type smoothness of 10 to 150 seconds and an opacity of 80. ~ 90%, burst strength 1.5 ~ 2.0Kg
The water-based inkjet recording paper is characterized in that it is in the range of / cm ² .

In the ink jet recording paper of the present invention, the ink-receptive coating layer has a low coating amount, and in order to increase the ink absorbability of the ink-receptive coating layer, the recorded ink is the ink-receptive coating layer only. Instead, it is absorbed inside the paper layer, resulting in an apparently dry state.

The base paper used as a sheet support in the present invention is usually bleached kraft pulp as a main raw material, and an alkyl ketene dimer as an additive, a neutral sizing agent such as alkenyl succinic acid, a sulfuric acid band, and a high cationic content. Selective addition of fixing agents such as molecular electrolytes, clay, talc, calcium carbonate, calcined kaolin, fillers such as aluminum oxide, aluminum hydroxide and titanium oxide, and paper strength enhancing agents such as polyacrylamide polymers and starch. However, a paper having a good liquid absorbing property with a Steckigt sizing degree of 1 to 20 seconds, which is produced by a known paper machine, is preferably used.

When the Steckitt sizing degree of the base paper is less than 1 second, there is concern that strikethrough of the ink, irregular spreading of the ink, deterioration of water resistance of the dye, etc. may occur due to the relationship with the coating amount of the coating layer. When the human sizing degree exceeds 20 seconds, the ink absorbency becomes insufficient, and as a result, the ink receptive coating layer on the surface of the base paper is significantly thickened to exceed 10 g / m ² in order to maintain the absorbency at a constant level. Will be needed.

The basis weight of the base paper used in the present invention is determined by the end use of the print, but is 20 to 200 g / m ² ,
It is preferably 60 to 90 g / m ² . The density of the base paper is determined by the end use of printing and the amount of ink to be recorded, but is 0.60 to 0.75 g /
cm ³ is preferable. Base paper density is 0.60g / c
If it is less than m ³ , there is a concern that strike-through of the ink, irregular spreading of the ink, deterioration of water resistance of the dye and the like may occur. Further, if the density of the base paper exceeds 0.75 g / cm ³ , the ink absorbency will be insufficient, and as a result, the coating amount of the ink receptive coating layer will be increased.

The Oken type smoothness of the base paper used in the present invention is preferably 5 to 60 seconds. If the Oken type smoothness is less than 5 seconds, it is desirable because the ink absorbency is improved, but the ink dots are too tight and the dot diameter becomes small. On the other hand, when the Oken type smoothness exceeds 60 seconds, the ink absorbency deteriorates, leading to deterioration in image quality such as ink bleeding in the heavy color portion.

In the present invention, the smoothness, density, and basis weight of the base paper are controlled by adjusting the composition and amount of various auxiliaries such as pulp composition, beating conditions, fillers, sizing agents, and paper strengthening agents. The operating conditions, such as drying conditions and pressurizing conditions, can be appropriately selected and selected according to the paper machine used.

The pigment used in the ink receptive coating layer of the ink jet recording paper of the present invention is mainly composed of fine particle synthetic silicic acid which is a white pigment which is porous and has high ink absorption and enables clear color development. Preferably. The fine particle synthetic silicic acid is produced by a precipitation method or a gelling method and is used as secondary particles in which primary particles are strongly aggregated. The diameter of the primary particles and the denseness of the secondary aggregation determine the pore radius and the pore volume. Further, the voids between particles are determined by the shape and size of the secondary particles. As a result, there are two kinds of pores in the silica, and inside and between particles, and each of them affects the ink absorbency and the color vividness as the recording material for inkjet, and therefore has a balance with the ink absorbability of the base paper. It is necessary to select the optimum performance with.

Such fine particle synthetic silicic acid has an oil absorption of 1
In the coating liquid for forming the ink-receptive coating layer, 50 to 350 ml / 100 g, having an average particle diameter of 1 to 15 μm (Coulter counter method) in a dispersed state is used. In particular, those having an oil absorption of 200 to 300 ml / 100 g and an average particle diameter of 3 to 12 μm are preferably used because the ink absorption speed is high and the storage stability of the colored portion is good. Examples of usable white pigments other than fine particle synthetic silicic acid include kaolin clay, talc, zeolite, precipitated calcium carbonate, ground calcium carbonate, aluminum hydroxide, white carbon, organic pigments (plastic pigments) and the like.

The adhesive that can be used in the present invention includes polyvinyl alcohol and its derivatives, proteins such as casein,
Starch and its starch derivatives, conjugated diene polymer latex such as styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer, etc., acrylic polymer latex such as polymer or copolymer of acrylic acid ester and methacrylic acid ester , Vinyl-based polymer latexes such as ethylene-vinyl acetate copolymers, modified polymer latexes containing functional groups such as carboxyl groups and cationic groups of these various polymers, thermosetting resins such as melamine resins and urea resins Synthetic resin-based water-based adhesives, maleic anhydride copolymer resin-based, polyacrylamide-based, polymethylmethacrylate-based, polyurethane resin-based, unsaturated polyester resin-based, polyvinyl butyral-based, alkyd resin-based synthetic resin-based adhesives However, it has good adhesion to pigments and is compatible with water-based inks. For a good, since improving the absorbent, it is preferably used.

The optimum amount of the polymer adhesive for the ink-absorbent coating layer is determined depending on the end use of the recording paper, surface strength, etc., but generally 10 to 50% by weight of the total solid content of the coating layer is preferable. Is used in an amount of 15 to 35% by weight.

For coating the coating material of the present invention, known coating equipment such as a blade coater, a bar coater and an air knife coater are used. The sheet provided with the ink-receptive coating layer on the base paper can be used as it is as the recording paper of the present invention, but is preferably treated with, for example, a super calender or a gloss calender to give the surface smoothness. ..

The coating amount of the ink receptive coating layer of the ink jet recording paper of the present invention is determined by the end use,
There is no need to increase the amount unnecessarily as long as the ink absorbency, recording characteristics, storability, etc. are satisfied, and the ink is appropriately selected from the range of 1 to 10 g / m ² . If the ink-receptive coating layer is less than 1 g / m ² , the ink absorption capacity is often insufficient, and the image runs out, color bleeding occurs, the image blurs, the drying is slow, and the ink adheres to the roll.
It gets dirty. However, if an ink-receptive coating layer having a coating amount of more than 10 g / m ² is provided, the adhesiveness to paper is weakened due to the thick coating layer, which often causes the problem of clogging of the head nozzle, which is also expensive. It will be

The density of the ink receptive coating layer of the ink jet recording paper of the present invention is determined by the end use, and may be in the range that satisfies the ink absorption, recording characteristics, storability and the like. In the present invention, the density of the receptive coating layer is 0.70.
It is preferably 0.80 g / cm ³ . When the density of the ink receptive coating layer is less than 0.70 g / cm ³ , the ink absorbability is improved, which is desirable, but the ink dots are too tight and the dot diameter is small. On the other hand, 0.80 g / cm
^When it exceeds ³ , the ink absorption capacity is insufficient, the image runs out, color bleeding occurs, and the image blurs,
It dries slowly and ink adheres to the roll, causing it to become dirty.

The Oken type smoothness of the ink jet recording paper of the present invention is determined by the end use, and may be in the range satisfying the ink absorbency, recording characteristics, storability, etc., and 10 to 150 seconds in the present invention. The range is selected. When the smoothness is less than 10 seconds, the ink absorbability is improved, which is desirable, but the dots of the ink are too tight and the dot diameter becomes small. In addition, the surface is rough and the feel is bad,
The final printed matter also looks bad. On the other hand, when it is higher than 150 seconds, the ink absorption capacity is insufficient, the image runs out, color blurring occurs, the image blurs, the drying is slow, and the ink adheres to the roll and becomes dirty. In addition, since the paper adheres well, running troubles are likely to occur due to static electricity during actual printing. The surface property as described above is, for example, 30 to 30 steps in one to several steps with a super calendar.
It can be adjusted by applying a nip pressure of ˜300 kg / cm.

The opacity of the ink jet recording paper of the present invention is determined by adjusting the composition and amount of various auxiliaries such as pulp composition at the time of papermaking, beating conditions, fillers, sizing agents, paper strengthening agents and the like.
The operating conditions such as drying conditions and pressurizing conditions can be appropriately selected and selected according to the paper machine used. Further, the opacity can be controlled by appropriately selecting the type of pigment used in the coating material to be applied, and in the present invention, the range of 80 to 90% is preferable. When the opacity is less than 80%, the ink absorbency is too good to cause strike-through, and the amount of ink remaining on the surface is insufficient, so that the optical density and sharpness of the printed matter are insufficient. On the other hand, if it exceeds 90%, the ink absorption capacity is insufficient, the image runs out, color bleeding occurs, the image blurs, the drying is slow, and the ink adheres to the roll and becomes dirty.

The burst strength of the ink jet recording paper of the present invention can be adjusted by adjusting the composition and addition amount of various auxiliaries such as pulp composition at the time of papermaking, beating conditions, fillers, sizing agents, paper strengthening agents and the like.
Operating conditions such as drying conditions and pressurizing conditions can be appropriately selected and adjusted according to the paper machine used. Further, the burst strength can be controlled by appropriately selecting the type and amount of the adhesive used in the coating material to be applied.

Inkjet paper forms an image by absorbing and drying the ink onto a base paper and an ink receptive coating layer. Therefore, the paper may be uneven (usually referred to as cockling) after the ink is evenly absorbed and particularly after printing with a water-based ink.

In the present invention, the burst strength is determined by the texture, homogeneity,
Since it is a measure of resistance to convex deformation of paper, it is selected as a guideline for optimizing the uniformity of printed dots and cockling after printing, and the burst strength is 1.5 to 2.0 Kg.
The range of / cm ² is used.

If the burst strength is less than 1.5 Kg / cm ² , the texture of the paper will be poor and uniform ink absorption will not be obtained. In addition, the ink absorbency is too good to cause strike-through, cockling appears remarkably, and the amount of ink remaining on the surface is insufficient, so that the optical density and sharpness of the printed matter are insufficient. .. On the other hand, the burst strength is 2.0 Kg / cm ²
If it exceeds, the texture of the paper will be improved and the ink absorption will be uniform,
Cockling also decreases, but the ink absorption capacity is insufficient,
The image runs out, color blurring occurs, the image blurs, the drying is slow, the ink adheres to the roll, and it becomes dirty.

[0029]

The present invention will be described in more detail with reference to the following examples, but of course the present invention is not limited thereto. In the following, all parts and% mean parts by weight and% by weight.

Example 1 20 parts of light calcium carbonate was added to a slurry of 100 parts of hardwood bleached kraft pulp (whiteness 91%) and 1 part of cationic starch and 0.05 part of alkyl ketene dimer neutral sizing agent were added. It was added and mixed sufficiently to make a papermaking raw material, and a fine paper having a basis weight of 74 g / m ² was produced using a Fourdrinier cylinder paper machine.

The obtained high-quality paper has a whiteness of 92%, an ash content of 15.0% (calculated as calcium carbonate), and a density of 0.70 g.
/ Cm ³ , Oken type smoothness was 21 seconds, and Steckigt sizing degree was 10 seconds.

Ink-jet recording paper was manufactured by coating one side of this base paper with paint-1 at a rate of 8 g / m ² using a bar coater, drying, and performing one-step treatment with an experimental super calendar.

Paint-1 Pigment: Fine particle silica oil absorption 220 ml / 100 g 100 parts (Fineseal manufactured by Tokuyama Soda Co., Ltd.) Adhesive: Polyvinyl alcohol (PVA117 manufactured by Kuraray Co., Ltd.) 25 parts

Example 2 Paint-1 was applied to the base paper used in Example 1 by the same procedure as in Example 1 and dried, and the nip pressure of the super calender for experiment was increased to carry out one-step treatment to prepare an ink jet recording paper. Manufactured.

Example 3 By the same operation as in Example 1, the paint-2 having the following formulation was applied to the base paper used in Example 1, dried, and then subjected to a one-step treatment with a super calender for experimentation to prepare an ink jet recording paper. Was manufactured.

Paint-2 Pigment: Fine particle silica oil absorption 260 ml / 100 g 100 parts (Mizukasil Mizusawa Chemical Co., Ltd.) Adhesive: Silanolated polyvinyl alcohol 25 parts (R-2105 Kuraray Co., Ltd.)

Example 4 The same procedure as in Example 1 was carried out except that the base paper used in Example 1 was coated with paint-2 at a rate of 5 g / m ² , coating, drying, and further using a supercalender for experiment. Inkjet recording paper was manufactured by processing.

Comparative Example 1 The base paper used in Example 1 was coated with paint- ^{2 at} a rate of 15 g / m ² , dried, and subjected to a one-step treatment with an experimental super calendar to produce an ink jet recording paper.

Comparative Example 2 Coating material-1 was applied to the base paper used in Example 1 by the same procedure as in Example 1 and dried, and the nip pressure of the experimental super calender was increased to carry out one-step treatment to prepare an ink jet recording paper. Manufactured.

Comparative Example 3 By the same operation as in Example 1, the basis weight was 102.5 g /
m ² , density 0.81 g / cm ³ , Oken smoothness 98 seconds,
Stockigt sizing degree of 30 seconds to produce a base paper, coating paint -2 rate of 8 g / m ² on one surface, and dried, to produce an ink jet recording paper by the single-stage process in a laboratory supercalender.

Comparative Example 4 By the same operation as in Example 1, a base paper having a basis weight of 42 g / m ² , a density of 0.57 g / cm ³ , a smoothness of 10 seconds and a Steckigt sizing degree of 2 seconds was produced, and one side thereof was prepared. 8g / m of paint-1
^The ink-jet recording paper was manufactured by coating at a ratio of ² , dried, and then subjected to a one-step treatment with an experimental super calendar. The evaluation results of these coated papers are shown in Tables 1 and 2. The inkjet recording characteristics were evaluated by the following methods.

(1) Recording characteristics An ink jet printer (Paint jet: manufactured by HP) was used to perform ink absorption, color density, dot shape and cockling. To evaluate the ink absorbency, the number of seconds until the printed ink dries was measured. 5
Seconds or less are indicated by ◯, 6 to 10 seconds by Δ, and 11 seconds or more by x. For the vividness of color development, the color development of yellow, magenta, and cyan color inks was visually evaluated. Colors with good color development are indicated by ○, △, and ×. The dot shapes are indicated by ◯, Δ, and x, starting from a shape close to a perfect circle. Cockling is indicated by O, Δ, and X from the smallest cockling.

(2) Smoothness The Oken type smoothness was measured by the method of "Tester / Measuring instrument for paper and printing" edited by Research Institute of Printing Bureau, Ministry of Finance, and the ink receptive coating layer side was measured.

(3) Density The density of base paper and recording paper is measured according to JIS-P-8118.
Was used. The density of the ink-receptive coating layer is JIS-P by coating the release paper with paint and separating the coating layer from the paper.
It was measured by the method according to -8118.

(4) Basis weight The basis weight was measured by the method according to JIS-P-8124.

(5) Opacity The opacity was measured by the method according to JIS-P-8138.

(6) Bursting strength The method of JIS-P-8131 was used to measure the bursting strength.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

INDUSTRIAL APPLICABILITY The ink jet printer recording paper of the present invention has excellent color development and dot shape, and has the effect of enabling high speed ink jet printing.

Claims (1)

[Claims] 1. A cellulose pulp as a main component, Oken type smoothness of 5 to 60 seconds, and density of 0.60 to 0.75 g / c.
m ³ and basis weight of 20 to 200 g / m ^{2 on} at least one surface of the base paper, oil absorption of 150 to 350 ml /
An ink-receptive coating layer containing 100 g of fine particle synthetic silicic acid and a water-soluble polymer adhesive as main components is provided in an amount of 1 to 10 g / m ² ,
Further, the density of the ink receptive coating layer is 0.70 to 0.8.
0 g / cm ³ , and the inkjet recording paper has an Oken type smoothness of 10 to 150 seconds and an opacity of 80 to 90.
%, The burst strength is in the range of 1.5 to 2.0 Kg / cm ² , an aqueous inkjet recording paper.