JPH03251487A - Sheet for ink jet recording - Google Patents

Abstract

PURPOSE:To print a sharp image having high ink absorbing speed and large absorbing capacity and excellent in preservability, in an aqueous ink jet type printer, by using special precipitated calcium carbonate. CONSTITUTION:An ink receiving coating layer based on precipitated calcium carbonate wherein oil absorbency is 30 - 60 ml/100g, a specific surface area is 5 - 15 m<2>/g and primary needle particles having a length of 0.2 - 2 mum form secondary bur-like flocs having a particle size of 1 - 5 mum and a water-soluble polymer adhesive is provided to the single surface of a base material in an amount of 2 - 30 g/m<2>.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a water-based ink recording material, and more specifically to an improved color inkjet blink having excellent color development, image storage stability, dot shape, etc. Regarding recording sheets for use.

[Prior Art] Ink sheet printers that use water-based ink have improved performance, especially printing speed, resolution, gradation, etc., and have improved the ability to absorb ink quickly, have a high absorption capacity, and produce regular ink dots on recording materials. More advanced characteristics are required regarding bleeding, etc. For example,
Japanese Patent No. 8084 discloses a method for producing an ink sheet recording medium using synthetic fine-grained silica and having high color reproducibility and color density when printed with a water-based ink having gloss and high ink absorption. In this way, synthetic fine particle silicic acid,
In other words, amorphous synthetic silica has a fast ink absorption speed,
It is considered to be the most excellent material because it has a large ink absorption capacity, the ink spreads small (the dot shape is close to a circle), and it does not impair the color development of the dye.

However, the receptive coating layer of the recording sheet, which is mainly composed of fine silica, not only absorbs ink;
The dye is adsorbed onto the silica of the receiving layer while quickly absorbing the solvent such as water in the ink throughout the layer, making the color vivid, but it has a serious drawback of impairing the stability of the dye.

Precipitated calcium carbonate is also commonly used as a main component of the receptor layer of recording sheets. Precipitated calcium carbonate is generally produced by the precipitation method, and is sometimes used in the form of primary particles, but it is usually produced in the form of strongly or slightly agglomerated particles.
As the particles become secondary particles, various types of pores are created between the particles.
The absorbency of the ink used as a recording material for inkjet printing and the vividness of color development are affected. That is, it is inferred that the liquid absorbency, dye color development, concealment, adsorption, etc. are determined by the shape of the primary particles of precipitated calcium carbonate, the shape and density of secondary aggregation, etc.

Calcitic calcium carbonate, which is generally used in coated printing paper, has many primary particles that are cubic in shape (but in secondary agglomerated particles of such calcium carbonate particles, there are gaps between the particles). It tends to be dense and absorb ink poorly.

The oil absorption amount of fine silica, which is generally used for inkjet paper, is 100 ml/100 g to 350 mI;! ,
/100g, specific surface area is 100m2/g ~ 500m2/
g range, but these are not considered as indicators of lipophilicity (they are considered indicators of the absorption and retention capacity of water-based inks, and can also be applied to precipitated calcium carbonate. However, if the ink absorption is larger than necessary, the printed dot shape becomes too small (too much) and the coloring density decreases, which is preferable.

Furthermore, when aragonitic long columnar calcium carbonate is used as the receiving layer of an inkjet recording sheet, there is a drawback that the dot diameter is too small (too small).

[Problems to be Solved by the Invention] In view of the current situation, the present inventor has searched for a material suitable for a recording material having more advanced characteristics in an aqueous inkjet printer, and as a result, has developed a material to replace synthetic silica and cubic calcium carbonate. The present invention was completed by discovering that a special precipitated calcium carbonate can be used for this purpose.

Therefore, an object of the present invention is to provide an inkjet printer that has a fast ink absorption speed, a large absorption capacity, can print sharp high-resolution images at high speed, and has excellent image storage stability in an inkjet printer that uses water-based ink. The objective is to provide recording materials.

"Means for solving the problem" The present invention has an oil absorption amount of 30rnj2/100g on one side of the base material.
~60rnj2/100 g, specific surface area 5m2/g~
The main ingredients are precipitated calcium carbonate and water-soluble polymer adhesive, in which acicular primary particles with a length of 15 m2/g and a length of 0.2 to 2 μm form bur-like secondary aggregates of 1 to 5 μm. This is a recording sheet characterized by having an ink receptive coating layer of 2 g/m2 to 30 g/m2 as a component.

The precipitated calcium carbonate used in the present invention belongs to the calcite type in crystal classification, and if the length of the primary particles is 0.2 μm or less, there are no pores formed in the particles of the secondary aggregates, so the ink On the other hand, if the length of the primary particles is 2 μm or more, the particle size of the secondary aggregates becomes too large and the coated surface becomes rough, so the length should be 0.2 to 2 μm.
It is preferable that needle-like primary particles of about m in size form bur-like secondary aggregates of 1 to 5 μm, particularly 1 μm
It is most preferable that acicular primary particles of about 100 to 100 µm form secondary aggregates of 2 to 3 μm in size. It is also preferable that the particle size distribution of the primary particles be narrow in order to achieve image clarity.

In addition, if the oil absorption amount of the precipitated calcium carbonate used in the present invention is 30 mg or less than 7100 g, the capacity to absorb ink will be insufficient and the ink will spread on the receiving surface, which is undesirable. The ink absorption becomes larger than necessary, and the diameter of the printed dots becomes small (
If it becomes too much, the color density will drop, so the amount of precipitated calcium carbonate to be supplied is preferably 60 mff/100 g or less. Suitable precipitated calcium carbonate having an oil absorption within this range has a specific surface area of 5 m''/g to 15 m2/g.

The adhesives used in the present invention include proteins such as polyvinyl alcohol and casein, and natural or synthetic water-soluble polymers such as starch and starch derivatives, which have good adhesion to precipitated calcium carbonate and have good affinity with water-based inks. Although it is preferred because of its good properties, polymer latexes such as polyvinyl acetate and styrene-bucdiene can also be used in combination.

The composition of precipitated calcium carbonate, an absorbent pigment, adhesive, etc. constituting the receptive layer for the present invention is determined based on the absorption behavior of the aqueous ink receptive layer and the strength requirements of the coating layer.

In addition, this formulation is also restricted by the requirements for operational characteristics of the aqueous coating solution, such as viscosity, fluidity, and drying properties of the coating film.

The ink-receptive coating layer is 2 to 30 g/m2, but if the coating layer is too small, ink absorption will be insufficient, and if it is too large, it will be unsuitable. Any known method may be selected and carried out depending on the concentration and viscosity of the coating solution.

For the purpose of the present invention, the water-based polymer adhesive has a coating layer solid content of 2
0 to 50% by weight, preferably 25 to 35% by weight,
Cationic vinyl acetate copolymer (emulsion polymer)
is 2 to 25% by weight of the solid content of the coating layer, preferably 5 to 15% by weight of the solid content of the coating layer.
% by weight is used.

The sheet-like support used in the present invention is preferably paper whose main material is ordinary wood bulbs, but synthetic fibers,
Synthetic pulp may also be mixed. The thickness of the support is determined by the end use of the print, but is between 10 and 200 μm9
The basis weight used is preferably 20 to 200 g/m2. The pH of the sheet-like support is preferably in the range of 4 to 8; if the pH is low, there is a risk of discoloration during long-term storage, and if the pH is high, the water resistance and storage stability of the dye in the image will be poor. The Steckigt sizing degree of the sheet-like support is preferably 2 to 10 seconds,
If the size degree is low, there are concerns such as print image bleed through, irregular spreading of ink, and decreased water resistance of dyes, etc. If the size degree is high, ink absorption will be poor, so in order to maintain absorbency, support is required. The ink receiving layer on the body surface is 10g/m2.
It will be necessary to increase it considerably.

In the present invention, the effects of the receiving layer, such as excellent ink absorption, are improved by using neutral paper made with 30% by weight or less of light calcium carbonate and a pH of 6 to 8.

[Examples] The present invention will be described in more detail with reference to Examples below, but the present invention is of course not limited thereto.

Example 1 20 parts by weight of calcite-based light calcium carbonate (PC: manufactured by Shiroishi Kogyo Co., Ltd.) was added to an aqueous suspension of 100 parts by weight of bleached hardwood kraft bulb with a whiteness of 91%, and further cationic starch (K-1-F) was added to the suspension. : Manufactured by Tamago National Co., Ltd.) 1 part by weight,
A papermaking raw material was obtained by adding 0.05 parts by weight of a neutral sizing agent (Fiberan 81, manufactured by Tamago National Co., Ltd.) and 15 parts by weight of sulfuric acid.

Using this raw material, high-quality paper (referred to as base paper) was produced as a sheet-like support using a conventional Fourdrinier multi-tube paper machine. The whiteness of the base paper is 92%, and the ash content (as calcium carbonate) is 15.0.
%, Steckigt sizing degree was 5 seconds, and pH was 65.

5 g of paint-1 consisting of the following composition on one side of the base paper
/ m 2 bar coating and drying to prepare an inkjet recording sheet with a receiving layer.

Composition of Paint-1 Primary particles are needle-shaped, secondary particles are bur-shaped Calcium 100 parts by weight Site-based precipitated calcium carbonate (Note 1) (Univer 70 manufactured by Nishakuishi Kogyo Co., Ltd.) (Note 1) The oil absorption amount is 55.0 m/100 g, the average particle diameter is 25 μm, and the specific surface area is 13.0 m 2 /g.

20 parts by weight of polyvinyl alcohol (PVA
117: manufactured by Kuraray Co., Ltd.) Polyethyleneimine quaternary ammonium salt 10 parts by weight (manufactured by Nippon Shokubai Kagaku Co., Ltd.) Concentration of coating liquid 15% by weight 0 Example 2 Paint-2 having the following composition was applied on one side of base paper. 5g/m
Ink sheller 1 to recording sheets were prepared by bar coating at a ratio of 1:2 and drying to provide a receptor layer.

Composition of Paint-2 Primary particles are acicular, secondary particles are squid-shaped Calcium 100 parts by weight Zite precipitated calcium carbonate (Note 1) (Univer 70 = Shiraishi Kogyo Co., Ltd.) Comparative Example 1 Group Coating material 3 having the composition shown below was coated on one side of the paper and dried to prepare an ink sheet recording sheet provided with a receiving layer.

Composition of Paint-3: 100 parts by weight of calcite with primary particle shape or spindle shape Precipitated calcium carbonate (Note 2) (PC manufactured by Shiraishi Kogyo Co., Ltd.) Polyvinyl alcohol copolymer 30 parts by weight (R-1)
130: manufactured by Kuraray Co., Ltd.) Cationic vinyl acetate copolymer emulsion (Yodozol I E508: manufactured by Kanebo N.C. Co., Ltd.) Coating liquid concentration: 20 parts by weight, 15% by weight 1 (Note 2) Oil absorption is 40 .0m/100g, average particle size is 30cm, and specific surface area is 5.0m2/g.

20 parts by weight of polyvinyl alcohol (PVA
117 Ri-7L/manufactured by Nippon Shokubai Kagaku Co., Ltd.) Polyethyleneimine quaternary ammonium salt 10 parts by weight 2 (manufactured by Nippon Shokubai Kagaku Co., Ltd.) Coating liquid concentration 15% by weight Comparative Example 2 Paint-4 having the following composition was applied on one side of the base paper. was bar coated at a rate of 5 g/m 2 and dried to prepare an ink sheet recording sheet provided with a receptor layer.

Composition of Paint-4: 100 parts by weight of calcite-based precipitated calcium carbonate (Note 3) whose primary particles are cubic in shape (manufactured by PZ, Shiraishi Kogyo Co., Ltd.) (E3) Oil absorption is 47.0+nj2/' 100 g, average particle size is 3.0 LLm, and specific surface area is 5.5 m2/g.

Polyvinyl alcohol (PVAl17: manufactured by Kuraray Co., Ltd.) 20 parts by weight Polyethyleneimine quaternary ammonium salt 10 parts by weight (manufactured by Nippon Shokubai Chemical Co., Ltd.) Coating liquid concentration 15% by weight Comparative Example 3 The following composition was applied on one side of the base paper. 5g/m' of paint-5!
An inkjet recording sheet was prepared by applying a bar coating at a ratio of 1,000 ml, and drying to provide a receiving layer.

Paint-5 Primary particles are needle-like and secondary particles are sea urchin-like. 100 parts by weight Gonitic precipitated calcium carbonate (Note 4) (Callite SA: manufactured by Shiraishi Kogyo Co., Ltd.) (Note 4) Oil absorption is 60.0 ml/100 g, the average particle diameter is 3.3 μm, and the specific surface area is 10.5 m2/g.

3 4 Polyvinyl alcohol (PVA11.7, manufactured by Kuraray Co., Ltd.) 20 parts by weight Quaternary polyethyleneimine 10 parts by weight Ammonium salt Coating liquid concentration 15% by weight
(PJ300S manufactured by Canon Inc.) was used to evaluate ink absorption, color density, dot shape, and storage stability.

Table 1 shows the results of quality evaluation of the recording sheets for ink sheller 1 prepared in Examples 1 to 2 and Comparative Examples 1 to 3.

Ink absorbency: The time (seconds) it took for the ink to dry from pudding 1 was measured, and the ink absorbency was ranked as excellent, good, fair, and slightly difficult.

・Yellow, magenta, cyan Color development 48 degrees・ Dot shape/ Preservability/ Check the color development of the color ink. Visually evaluate, excellent, good, Fair, slightly de-IL.

・The dots are close to a perfect circle Indicated as excellent, good, fair, or somewhat difficult. Ta.

・Atlas Fade Meter (manufactured by Toyo Seiki Co., Ltd.) by 24 Evaluate concentration after time exposure and is graded as excellent, good, fair, or somewhat difficult. did.

[Effects of the Invention] The ink sheller 1 to the liquid recording sheet for printers of the present invention has a high ink absorption speed and absorption amount, clear images, little bleeding of dots, excellent storage stability, and high resolution and color development. It enables high-speed inkjet full-color printing, and will greatly contribute to industry.

Claims (1)

[Claims] 1. Oil absorption amount on one side of the base material is 30ml/100g~60m
l/100g, specific surface area 5m^2/g ~ 15m^2/
g and 1 to 5 needle-shaped primary particles with a length of 0.2 to 2 μm.
An ink-receptive coating layer containing 2 g/m^2 to 30 g/m^2 of precipitated calcium carbonate and water-soluble polymer adhesive as main components forming a micrometer-sized bur-shaped secondary aggregate was provided. A water-based inkjet recording sheet characterized by: