JPH06262845A - Ink-jet recording form - Google Patents

Abstract

PURPOSE:To provide an ink-jet recording form wherein color development, uniformity of a dot and absorptivity of ink are excellent in an ink receptive coating layer of low coating amount. CONSTITUTION:An aqueous ink-jet recording form is equipped with base paper constituted of cellulose pulp as a main component and an ink receptive coating layer which is formed on one side of the base paper and has white pigment and aqueous polymer substance as the main component. The base paper is sheetlike and contains 55-80wt.% cellulose pulp which is restricted to <=5% moisture and dried and Steckigt sizing degree is regulated to 20-50 seconds. Thereby absorptivity of ink is excellent and also ink is uniformly absorbed. Therefore homogeneous and excellent color development and the shape of the dot are obtained and high-speed ink-jet printing is enabled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material. More specifically, the present invention relates to a water-based inkjet recording sheet which is provided with an ink-receptive coating layer having excellent color image characteristics on the surface of a base paper and has excellent dot uniformity and ink absorbability. is there.

[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.

For example, Japanese Unexamined Patent Publication (Kokai) No. 62-158084 discloses a method for producing an ink jet recording medium having high water-based ink absorbency, color reproducibility and color density by using fine particle synthetic silica. That is, in order to comply with the above-mentioned required characteristics, a coating layer containing a white pigment having an excellent liquid absorbing property such as fine particle synthetic silica as a main component is provided on the surface of a base paper containing 10 g / m ² or more of cellulose pulp as a main component. Providing is usually practiced.

On the other hand, in order to reduce the cost, an ink receptive coating layer is provided on the surface in a thin range of 1 to 10 g / m ² .
Moreover, so-called single-sided fine coated paper has been developed, which is intended to have sufficient performance. However, in such a lightly coated paper, since the coating layer is thin, a part of the pulp fiber is exposed on the surface, and the texture or unevenness of the base paper makes it easily affected by the ink absorbency (amount, speed), As a result, uneven absorption of ink is caused, which causes unevenness of dots.

Further, conventionally, not only the ink-receptive coating layer has been improved but also pulp has been improved in order to increase ink absorbency and suppress the spread of dots. For example, JP-A-62-162584 discloses an inkjet recording material containing 10% by weight or more of rag pulp. Further, JP-A-62-227685 discloses an ink jet recording material containing 10% by weight or more of recycled pulp, and JP-A-62-178383 discloses an ink jet recording material containing 5 to 50% by weight of dry ground pulp. JP-A-4-12880 discloses an ink jet recording material containing a pulp obtained by re-beating pulp beaten and dried so that the Canadian standard freeness is lowered by 20 ml or more together with undried pulp.

However, recording materials containing these improved pulps have very good ink absorbency, but on the other hand, they also have improved water absorbency and are of a type in which an ink receptive coating layer is provided on at least one surface of the base paper. In ink jet recording paper, the water component of the paint is taken up by the base paper when the paint that constitutes the ink receptive coating layer is applied, and the strength of the ink receptive coating layer formed decreases It is difficult to form the receptive coating layer, and there is a problem that unevenness in ink absorption and non-uniformity of dots occur.

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made earnest studies on the uniform absorption of ink in view of the present situation, and as a result, contained 55 to 80% by weight of cellulose pulp dried by restraining the water content to 5% or less. , Steckigt size degree is 2
It is possible to remarkably improve the uniformity of dots and the uniformity of ink absorption by providing an ink-receptive coating layer containing a white pigment having a high absorbability and an aqueous polymer substance on one surface of the base paper for 0 to 50 seconds. It was found that high quality and uniform images can be obtained by printing the thus produced recording paper by an ink jet method, and the present invention has been completed.

To explain the present invention in more detail, most of the base papers of conventional ink jet recording papers are obtained by beating pulp to an appropriate degree in water, adding a filler and various other additives to the paper, and making paper. According to the research conducted by the present inventor,
% To 50% by weight or less of the pulp, the water retention and stretchability of the base paper when the coating material for forming the ink-receptive coating layer is applied, that is, when it is wet. It has been found that the coating layer is reduced and a uniform coating layer is obtained.

Further, by using a restrained dry pulp having a water content of 5% or less, hydration and swelling with water during beating are less likely to occur, and the pulp is subdivided in a state closer to a dry state during beating, and The surface area increases, the ink adsorption area increases, and since the dry pulp of the present invention has a low water content, it is rigid in itself and prevents the adhesion between the beaten pulp fibers beaten in water to prevent voids inside the paper. It was found that the ink absorption capacity was increased and a sufficient ink absorption capacity was obtained.

Therefore, an object of the present invention is to print a high-quality image at a high speed using an ink jet printer using an aqueous ink, and to absorb the ink even when the ink-receptive coating layer is thinly applied. An object is to provide an inkjet recording paper having uniform properties.

[0011]

DISCLOSURE OF THE INVENTION The present invention relates to a base paper containing cellulose pulp as a main component, and an ink receptive coating formed on one surface of the base paper and containing a white pigment and an aqueous polymer as main components. And a layer of the base paper in the form of a sheet having a moisture content of not more than 5% and dried by drying 55
-80% by weight and has a Steckigt sizing degree of 20-
The present invention relates to a water-based inkjet recording paper characterized by being 50 seconds.

The pulp material contained in the sheet support used in the present invention is a softwood such as Akamatsu, Kuromatsu, Ezo pine, Todo pine, Japanese cedar, etc. , Kraft pulp, semi-chemical pulp, chemi-ground pulp, refiner ground pulp and waste paper pulp are appropriately selected and used.

The base paper as the sheet support used in the present invention comprises the above wood pulp as a main raw material, an internal additive sizing agent such as an alkyl ketene dimer and an alkenyl succinic acid as an additive, a sulfuric acid band, and a cationic starch. Adhesives such as fixing agents, clay, talc, light calcium carbonate, calcined kaolin, aluminum oxide, aluminum hydroxide, titanium oxide, etc., polyacrylamide-based polymers, paper-strengthening agents such as starch, etc. are appropriately selected and added internally, and rosin is added. System, petroleum resin system,
Composed of two or more copolymers of starch such as oxidized starch, acetylated starch and hydroxyethylated starch and its derivatives, polyvinyl alcohol and its derivatives, styrene, alkyd, polyamide, acryl, olefin, maleic acid and vinyl acetate. A base paper having a Steckigt sizing degree of 20 to 50 seconds, which has been sized by a surface sizing agent such as a synthetic resin type, a synthetic resin emulsion type or a wax type, is preferably used.

When the sizing degree of the base paper is less than 20 seconds, the water component of the paint is taken by the base paper when the paint constituting the ink-receptive coating layer is applied, and the strength of the ink-receptive coating layer formed. However, there is a problem in that it is difficult to form a uniform ink-receptive coating layer, unevenness in ink absorption, and non-uniformity of dots occur. On the other hand, when the sizing degree exceeds 50 seconds, the ink absorbency becomes insufficient, and as a result, the ink receptive coating layer on the surface of the base paper is set to 1 to maintain the absorbency at a constant level.
It is necessary to make it significantly thicker than 0 g / m ² .

The dry pulp used in the present invention is prepared by immersing the above pulp material in warm water for 24 hours, treating it with a known disintegrator such as a kneader, beater, or pulper for an appropriate period of time, and then making a thin paper with a pulp machine. And sheet 5% moisture
Use after drying. If the water content exceeds 5%,
The water retention of the pulp is high, and the elasticity is also high, and when the paint for forming the ink-receptive coating layer is applied, the water component of the paint is taken up by the base paper to form a uniform ink-receptive coating layer. Not only can not be formed, but also the rigidity of the pulp is weakened, the internal void volume when made into a sheet is reduced, sufficient ink absorption capacity is not obtained, and further hydration and swelling with water during beating tend to occur. Therefore, the pulp is less likely to be finely sheared. As a result, the ink absorption capacity is reduced, and the coating amount of the ink-receptive coating layer must be set to exceed 10 g / m ² , resulting in problems such as a reduction in coating layer strength and an increase in cost.

On the other hand, in the case of free-drying pulp using a flash dryer, even if the water content is 5% or less, the water retention and stretchability of the pulp become high, and when applying a paint for forming an ink-receptive coating layer. However, the water component of the paint is taken up by the base paper, making it impossible to form a uniform ink-receptive coating layer.

The use ratio of the dry pulp used in the present invention is preferably 55 to 80% by weight based on the total solid content of the base paper. 55
If it is less than 10% by weight, the stretchability of the base paper during coating is large and it is difficult to form a uniform coating layer. On the other hand, if it is more than 80% by weight, the paper strength etc. decreases and problems such as paper breakage during coating occur. Is undesirable because it causes

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, preferably used preferably has 60~120g / m ^2. The basis weight of the base paper for the present invention is selected from pulp composition, beating conditions, fillers, sizing agents, types and addition amounts of various auxiliaries such as paper strengthening agents, and drying conditions and pressurizing conditions. It can be adjusted by appropriately selecting operating conditions suitable for the paper machine used.

The pigment used in the ink-receptive coating layer used in the present invention preferably contains a white pigment as a main component, which is porous, has high ink absorbency, and enables clear color development. Examples of such pigments include fine particle synthetic silica, precipitated calcium carbonate, ground calcium carbonate, calcium silicate, aluminum hydroxide, magnesium carbonate,
Examples include white carbon and organic pigments (plastic pigments). The use ratio of such a pigment is preferably 50 to 90% by weight of the total solid content of the coating layer. If it is less than 50%, the uniformity of ink absorption becomes insufficient, and if it exceeds 90%, the strength of the ink-receptive coating layer may decrease, which is not suitable.

The aqueous polymer used in the ink-receptive coating layer on the surface of the base paper of the present invention includes polyvinyl alcohol and its derivatives, proteins such as casein, starch and starch derivatives, styrene-butadiene copolymer, and methyl. Conjugated diene-based polymer latex such as methacrylate-butadiene copolymer, acrylic-based polymer latex such as polymer or copolymer of acrylic acid ester and methacrylic acid ester, vinyl-based polymer such as ethylene-vinyl acetate copolymer Latex, or modified polymer latex containing functional groups such as carboxyl groups and cationic groups of these various polymers, synthetic resin-based aqueous resins such as thermosetting resins such as melamine resins and urea resins, maleic anhydride copolymers Resin type, polyacrylamide type, polymethylmethacrylate type, polyuret Polymers such as synthetic resin adhesives such as tan resin type, unsaturated polyester resin type, polyvinyl butyral type and alkyd resin type are preferably used.

The proportion of the aqueous polymer resin used in the ink-receptive coating layer is 10 to 50% by weight of the total solid content of the coating layer.
It is preferably 10 to 35% by weight. If it is less than 10%, the adhesive strength will be insufficient, and there is a concern that the strength of the coating layer will decrease. On the other hand, when it exceeds 50%, the adhesiveness is increased, but the use ratio of the pigment is reduced, and as described above, there is a problem in the uniformity of ink absorption, which is not suitable.

Known coating equipment such as a blade coater, a bar coater and an air knife coater is applied to the coating for forming the ink receptive coating layer of the present invention. The sheet provided with the ink-receptive coating layer on the base paper can be used as it is as the recording sheet of the present invention, but is treated with, for example, a super calendar or a gloss calendar,
It is also possible to provide surface smoothness.

The coating amount of the ink absorptive coating layer obtained in the present invention is determined by the end use, and does not need to be unnecessarily increased as long as the ink absorptivity, recording characteristics, storability, etc. are satisfied. It is appropriately selected from the range of 10 g / m ² . If the ink-receptive coating layer is less than 1 g / m ² , the ink absorption capacity is insufficient in many cases, and the image runs out, color bleeding causes blurring of the image, or the ink is attached to the roll due to slow drying. However, problems such as getting dirty occur. On the other hand, when the ink receptive coating layer having a thickness of more than 10 g / m ² is provided, the adhesiveness to the paper is weakened because the coating layer is thick, and problems such as clogging of the head nozzle often occur, and the cost is further reduced. Is also expensive.

[0024]

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, "parts and%" means "parts by weight of solids" and "% by weight of solids".

Example 1 Hardwood bleached kraft pulp (water content 37%) was dipped in warm water at 35 ° C. for 24 hours, treated with a pulper for an appropriate time, and then made into a thin layer with a pulp machine, and dried pulp A ( Water content 4%). Add 25 parts of light calcium carbonate to a slurry of 95 parts of dry pulp A and 5 parts of bleached hardwood kraft pulp, add 0.8 parts of cationic starch and 0.05 parts of alkyl ketene dimer type neutral sizing agent, and mix well. Mix and use it as a papermaking raw material to form wet paper using a fourdrinier cylinder paper machine, make the felt side adhere to the surface of the Yankee dryer, dry the water to 10%, and apply paint-1 on both sides with a size press. 3 g / m ^{2 was} applied, dried, and dried to a water content of 7% to produce high-quality paper having a weight of 72 g / m ² .

The dry pulp content was 75.5% based on the total solid content of the base paper, the ash content of the obtained high-quality paper was 13.0% (calcium carbonate conversion), and the Steckigt sizing degree was 35 seconds. Ink-jet recording paper was manufactured by coating Paint-2 at a rate of 7 g / m ^{2 on} one surface of the obtained high-quality paper in a laboratory using a test blade coater and drying it to form a coating layer.

[0027] The paint -1 Ingredient weight starch 100 parts (Prince Ace A: manufactured by Oji Cornstarch)

[0028] Paint -2 Ingredient weight particulate silicic acid 100 parts (Fine Seal, manufactured by Tokuyama Soda) Polyvinyl alcohol 25 parts (PVA117: manufactured by Kuraray)

Example 2 25 parts of light calcium carbonate was added to the slurry of 75 parts of dry pulp A prepared in Example 1 and 25 parts of bleached hardwood kraft pulp, and 0.8 parts of cationic starch and alkyl ketene dimer type neutral were added. Add 0.05 parts of a sizing agent, mix well and use as a papermaking raw material, form a wet paper web using a fourdrinier multi-cylinder paper machine, and bring the felt surface into close contact with the surface of a Yankee dryer to obtain a water content of 10%. And coated with a size press at 3 g / m ² on both sides, dried, and dried to a water content of 7% to produce high-quality paper of 72 g / m ² in weight per square meter.

The dry pulp content was 59.6% based on the total solid content of the base paper, the ash content of the obtained high-quality paper was 12.4% (calcium carbonate conversion), and the Steckigt sizing degree was 37 seconds. An ink jet recording paper was manufactured by applying a paint- ^{2 at} a rate of 6 g / m <2> on one surface of the obtained high quality paper using a test blade coater in a laboratory and drying to form a coating layer.

Example 3 Waste paper pulp (water content 32%) was soaked in warm water at 35 ° C. for 24 hours, treated with a beater for 3 hours, and then made into a thin layer with a pulp machine, and dried pulp B (water content 4). .5%). 25 parts of light calcium carbonate, dry pulp B
90 parts, 10 parts of hardwood bleached kraft pulp, 0.8 parts of cationic starch and 0.05 parts of alkyl ketene dimer neutral sizing agent were added and mixed sufficiently to make a papermaking raw material. Wet paper is formed using a multi-cylinder paper machine, the felt surface is brought into close contact with the surface of a Yankee dryer, the water content is dried to 10%, and the paint is applied with a size press.
1 on both sides with 3 g / m ² coated, dried, to produce a high quality paper of basis weight 68 g / m ² and dried to 7% moisture.

The dry pulp content was 71.5% based on the total solid content of the base paper, the ash content of the obtained fine paper was 13% (calcium carbonate conversion), and the Steckigt sizing degree was 23 seconds.
On one surface of the obtained high-quality paper, a paint-2 was applied at a rate of 6 g / m ^{2 in} a laboratory using a test blade coater,
An inkjet recording paper was manufactured by drying to form a coating layer.

The paint -3 Ingredient weight of starch 66 parts (Oji Ace B: manufactured by Oji Corn Starch) Polyvinyl alcohol 34 parts (PVA 105: Kuraray)

Example 4 22 parts of light calcium carbonate was added to the slurry of 90 parts of the dry pulp B prepared in Example 3 and 10 parts of bleached hardwood kraft pulp, and 2.1 parts of cationic starch and alkyl ketene dimer type neutral were added. Add 0.1 parts of a sizing agent, mix well and use it as a papermaking raw material to form a wet paper web using a Fourdrinier cylinder paper machine, and bring the felt surface into close contact with the surface of a Yankee dryer to obtain a water content of 10%. And coated with a size press at 4 g / m ² on both sides, dried, and dried to a water content of 6% to produce high-quality paper having a weight of 74 g / m ² .

The dry pulp content was 72.5% based on the total solids content of the base paper, the ash content of the obtained high-quality paper was 11.2% (calcium carbonate conversion), and the Steckigt sizing degree was 47 seconds. An ink jet recording paper was manufactured by applying a paint- ^{2 at} a rate of 6 g / m <2> on one surface of the obtained high quality paper using a test blade coater in a laboratory and drying to form a coating layer.

Comparative Example 1 25 parts of light calcium carbonate was added to a slurry of 100 parts of hardwood bleached kraft pulp, 1 part of cationic starch and 0.05 part of alkyl ketene dimer neutral sizing agent were added and mixed thoroughly. As a raw material for papermaking, a wet paper web is formed by using a Fourdrinier cylinder paper machine, a felt surface is brought into close contact with the surface of a Yankee dryer, moisture is dried to 10%, and paint-1 is applied on both sides with a size press. 3 g / m ^{2 was} applied, dried, and dried to a water content of 6% to produce high-quality paper having a basis weight of 70 g / m ² .

The dry pulp composition was 0% with respect to the total solid content of the base paper, the ash content of the obtained high-quality paper was 12% (calcium carbonate conversion), and the Steckigt sizing degree was 30 seconds. An ink jet recording paper was manufactured by applying a paint- ^{2 at} a rate of 6 g / m <2> on one surface of the obtained high quality paper using a test blade coater in a laboratory and drying to form a coating layer.

Comparative Example 2 20 parts of light calcium carbonate was added to the slurry of 120 parts of pulp B prepared in Example 3 to give a cationic starch 1
Part, 0.05 part of alkyl ketene dimer type neutral sizing agent, mixed well and used as a papermaking raw material to form a wet paper web using a fourdrinier cylinder paper machine, and felt surface on the surface of Yankee dryer. And dry it to 10% moisture,
Paint-1 was applied at 3 g / m ² on both sides with a size press, dried, and dried to a water content of 6% to produce high-quality paper having a weight of 70 g / m ² .

The dry pulp content was 85.1% based on the total solid content of the base paper, the ash content of the obtained high-quality paper was 10.6% (calcium carbonate conversion), and the Steckigt sizing degree was 28 seconds. Ink-jet recording paper was manufactured by coating Paint-2 at a rate of 7 g / m ^{2 on} one surface of the obtained high-quality paper in a laboratory using a test blade coater and drying it to form a coating layer.

Comparative Example 3 25 parts of light calcium carbonate was added to a slurry of 90 parts of dry pulp A prepared in Example 1 and 10 parts of bleached hardwood kraft pulp, and 0.8 parts of cationic starch and alkyl ketene dimer type neutral were added. Add 0.04 parts of sizing agent, mix well and use it as a papermaking raw material to form wet paper using a fourdrinier multi-cylinder paper machine. until dried, both sides with 2 g / m ² coated with a coating material -1 a size press, dried, to produce a high quality paper of basis weight 68 g / m ² and dried to 7% moisture.

The dry pulp content was 71.5% based on the total solids content of the base paper, the ash content of the obtained high-quality paper was 13% (calcium carbonate conversion), and the Steckigt sizing degree was 14 seconds.
Applying Paint-2 at a rate of 7 g / m ^{2 on} one side of the obtained high-quality paper in a laboratory using a test blade coater,
An inkjet recording paper was manufactured by drying to form a coating layer.

Comparative Example 4 23 parts of light calcium carbonate was added to the slurry of 90 parts of dry pulp A prepared in Example 1 and 10 parts of bleached hardwood kraft pulp, and 2 parts of cationic starch and neutral ketene dimer neutral sizing agent were added. Add 0.2 parts and mix well to make a papermaking raw material, form a wet paper web using a fourdrinier multi-cylinder paper machine, make the felt surface adhere to the surface of a Yankee dryer, and dry it to 10% moisture. And paint with a size press-
3g was coated on both sides at 5 g / m ² , dried, and dried to a water content of 7% to produce high-quality paper having a basis weight of 74 g / m ² .

The dry pulp content was 71.9% based on the total solid content of the base paper, the ash content of the obtained high-quality paper was 11.4% (calcium carbonate conversion), and the Steckigt sizing degree was 72 seconds. Ink-jet recording paper was manufactured by coating Paint-2 at a rate of 7 g / m ^{2 on} one surface of the obtained high-quality paper in a laboratory using a test blade coater and drying it to form a coating layer.

Comparative Example 5 Hardwood bleached kraft pulp (water content 37%) was immersed in warm water at 35 ° C. for 24 hours, and then treated with pulper for 6 hours,
Dry pulp C (water content 4%) was prepared with a flash dryer. 25 parts of light calcium carbonate, dry pulp A9
5 parts, and 5 parts of hardwood bleached kraft pulp were added to a slurry, 0.8 parts of cationic starch and 0.05 parts of an alkyl ketene dimer type neutral sizing agent were added, and they were sufficiently mixed to prepare a papermaking raw material. Wet paper is formed using tubular papermaking, and the felt surface is brought into close contact with the surface of the Yankee dryer to remove moisture.
Dry to 0% and use size press to paint-1 on both sides 3
g / m ² coating, drying, water content 7%
A fine paper of 4 g / m ² was produced.

The dry pulp content was 75.5% with respect to the total solid content of the base paper, the ash content of the obtained fine paper was 13.0% (calcium carbonate conversion), and the Steckigt sizing degree was 38 seconds. An ink jet recording paper was manufactured by applying a paint- ^{2 at} a rate of 6 g / m <2> on one surface of the obtained high quality paper using a test blade coater in a laboratory and drying to form a coating layer.

Table 1 shows the evaluation results of these coated papers. The inkjet recording characteristics were evaluated by the following methods. Recording Performance Inkjet Printer (Desk Writer-
C: manufactured by HP) was used for ink absorbency, uniformity of ink color density, vividness of color development, and dot shape.

To evaluate the ink absorbency, the number of seconds until the printed ink dries was measured. 5 seconds or less ○, 6
-10 seconds is indicated by Δ, and 11 seconds or more is indicated by x.

The uniformity of the color density of the ink was determined by solid printing and measuring the optical densities of 20 randomly selected locations with a Macbeth densitometer (made by Kollmorgen Corp).
A variation of 0.05 or less is ◯, 0.06 to 0.1 is Δ,
0.11 or more is shown by x.

The vividness of coloring is yellow, magenta,
The color development of the cyan color ink was visually evaluated. The items with good color development are shown by O, Δ, and X.

The shape of the dot is from a circle close to a circle,
It is shown by Δ and ×. Table 1 shows the evaluation results of these coated papers.

[0051]

[Table 1]

As can be seen from Table 1, the ink jet recording papers obtained in Examples and Comparative Examples showed almost no difference in the vividness of the color development, but the ink absorbency, the uniformity of the color development density, and the dot shape. Regarding the above, the inkjet recording papers obtained in Examples are superior to those in Comparative Examples.

[0053]

INDUSTRIAL APPLICABILITY The ink jet printer recording paper of the present invention has not only excellent ink absorption but also uniform ink absorption, so that it has uniform and excellent color development and dot shape, and high speed. This has the effect of enabling inkjet printing.

Claims (1)

[Claims] 1. A base paper containing cellulose pulp as a main component, and an ink-receptive coating layer formed on one surface of the base paper and containing a white pigment and an aqueous polymer as main components. The base paper is in the form of a sheet, and contains 55 to 80% by weight of cellulose pulp which is constrained and dried to have a water content of 5% or less,
A water-based inkjet recording paper having a Steckigt sizing degree of 20 to 50 seconds.