JPH0717085B2 - Recording paper and ink jet recording method using the same - Google Patents

Abstract

A recording paper comprises a fibrous substrate paper on the surface of which a silicon containing type pigment and a fibrous material of the substrate paper are present in a mixed state, said recording paper having a Stöckigt sizing degree ranging from 0 to 15 sec. and a basis weight ranging from 90 to 200 g/m<2>.

Description

Description: TECHNICAL FIELD The present invention relates to a recording paper useful for ink jet recording and an ink jet recording method using the same, and in particular, it is excellent in the absorbability of aqueous ink and the coloring property of a coloring material. The present invention relates to a low-cost recording paper that does not cause strike-through and cockling, and an ink jet recording method using the same.

[Conventional technology]

As a recording paper for conventional ink jet, (1) general paper containing pulp as a main component, which is made into a low-size paper like filter paper or blotter paper, (2) as base paper (3) JP-A-52-53012, JP-A-55-53012, in which a size-sensitive paper is used and a porous filler having a large oil absorption such as silica or zeolite is coated to form an ink absorption layer. There are known base papers of low size having a coating layer as disclosed in JP-A-11829 and JP-A-59-38987.

Although the recording paper (1) has excellent ink absorbency, since the ink penetrates deeply into the fiber layer of the paper, the coloring property of the coloring material in the ink is poor, and the ink softly adheres to the fibers on the paper surface. As a result, a phenomenon called feathering occurs, the dots do not become circular, and the dots become jagged, the resolution is lowered, and high-quality images cannot be obtained.

In the recording paper (2), since the ink absorption layer is porous and uniform, a good dot shape and resolution can be obtained, but in order to impart sufficient ink absorption,
There is also a problem that the ink absorption layer has to be thick and the coating needs to be performed a plurality of times because one coating is insufficient.

If the ratio of the filler to the binder (P / B) in the ink absorbing layer is increased too much in order to further improve the ink absorbency, so-called powder falling due to the falling of the filler occurs, and the paper feeding roller slips, There are drawbacks such as clogging of the ink jet nozzle.

The recording paper (3) has an advantage that a recording material having excellent ink absorbability and excellent coloring property of the coloring material can be obtained as compared with (2) even when a relatively thin coat layer is provided. . However, a recording method with higher resolution and a higher ink adhesion density is required, and when the recording paper (3) is applied to such a method, a large amount of ink is applied to the base paper even if the ink absorption is sufficient. Since the ink permeates, the coloring property of the coloring material and the resolution decrease, and it is difficult to achieve both of these properties and the ink absorbability.

Furthermore, the pulp fibers in the base paper swell with the ink, the printed portion is deformed into a wavy shape, a problem called cockling,
The so-called strike-through problem occurs in which the ink reaches the back surface of the paper. These problems not only impair the quality of the recorded image, but the crocking causes rubbing between the recording paper and the head during printing, damaging the image, and the strike-through when the other recording papers are overlaid. It may cause backsiding, both of which are serious problems.

These phenomena are problems peculiar to the recording paper (3) in which ink is received by the entire recording material, and have become particularly apparent as high-resolution images by ink jet recording are required. However, even though the above-mentioned problems are peculiar to the recording paper (3), detailed studies on these problems have not yet been made.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a recording paper that is produced at a relatively low cost with less powder falling, and has excellent ink absorbency and coloring property of a coloring material, and an ink jet recording method using the same.

A further object of the present invention is to provide a recording paper suitable for providing a high-definition image that does not cause problems such as cockling and strike-through in the printing portion.

[Means and Actions for Solving Problems]

 The above object is achieved by the present invention described below.

That is, the present invention has a coating layer containing a silicon-containing pigment on the surface of the fibrous base paper, and the surface of the coating layer exhibits a mixed state of the silicon-containing pigment and the fibrous substance of the base paper. The recording paper is characterized by having a Steckigt sizing degree in the range of 0 to 15 seconds and a basis weight in the range of 90 to 200 g / m ^2. It is an inkjet recording method in which a water-based ink is applied to paper to perform recording.

Next, the present invention will be described in more detail. The base paper used in the present invention is a sheet containing a fibrous substance and optionally a filler, and has a Steckigt sizing degree of 0 according to JIS P8122.
It should be in the range of 15 seconds (basis weight of 65 g / m ² standard), and it should have been prepared by a conventionally known acidic papermaking method or neutral papermaking method with an appropriate sizing agent to a sizing degree of 0 to 15 seconds. Both can be used. From the viewpoint of ink absorbency of the resulting recording paper, the sizing degree of the base paper is preferably in the range of 0 to 10 seconds,
More preferably, it is in the range of 0 to 5 seconds. Further, from the viewpoint of coating stability of the coating liquid, it is preferably one second or longer.

In addition, the basis weight of the base paper is also an important factor in achieving the intended purpose in the present invention. That is, the basis weight of the base paper used in the present invention needs to be in the range of 90 to 200 g / m ² , and when the basis weight is less than the above range, the so-called stiffness of the obtained recording paper is weak, and printing At the same time, there is a problem in transportability within the printer, and the ink absorption capacity of the recording paper is insufficient, so that the printing portion causes crocking, resulting in a decrease in image sharpness. Also, when recording using a printer having multiple recording heads, the convex portion caused by cockling may contact the head during recording, causing clogging of the head, etc. There is a problem that unevenness occurs.

Furthermore, since the ink receiving capacity is low, there is a problem in that the ink that cannot be completely received will pass through and the ink image on the upper recording paper will be transferred to the image on the lower recording paper when the prints are placed on top of each other. There are also problems such as occurrence of recording, and recording on the back side.

On the other hand, when the grammage exceeds the above range, the stress applied to the coating layer on the surface when the recording paper to be obtained is bent becomes strong, so that problems such as cracking, powder dropping, and peeling of the coating layer occur.

That is, during the coating process, repeated bending along the rolls of the coating machine causes cracks on the surface of the coating layer, which may cause image unevenness and powder drop later. Further, there is a problem that similar powder fall-off easily occurs during cutting of recording paper, storage after manufacturing, attachment to a printer, or even in a printer conveyance path. In particular, the powder drop that occurs during recording causes clogging of the recording head and is not preferable. Further, it is not preferable to thicken the base paper, which has a large expansion / contraction ratio with respect to humidity, because it causes a problem of curling.

The various problems mentioned above have a basis weight of 90 to 200 g as the base paper.
It is solved by adopting a base paper of / m ² .

Further, the thickness of the base paper used in the present invention is preferably in the range of 50 to 250 μm, and when the thickness is less than the above range, the so-called stiffness of the obtained recording paper is weak and the paper is conveyed in the printer during printing. However, there is a problem in that the ink absorption capacity of the recording paper is insufficient, and therefore, the printing portion is clogged and the sharpness of the image is deteriorated.

The fibrous substance constituting the above-mentioned base paper used in the present invention is
Mainly wood pulp represented by LBKP and NBKP,
If necessary, various synthetic fibers or glass fibers may be mixed.

The aqueous coating liquid used in the present invention mainly comprises a silicon-containing filler and an aqueous binder. As the silicon-containing filler, those which are hydrophilic and have a relatively large oil absorption amount according to JIS K5101 are preferable from the viewpoint of ink absorbency and color development of the coloring material, for example, silica, calcium silicate, aluminum silicate, silicic acid. Magnesium and the like can be mentioned. Among them, those having an oil absorption of JIS K5101 of 80 to 300 ml / 100 g are preferable, and those of 150 to 250 ml / 100 g are more preferable.

Incidentally, the above-mentioned silicon-containing filler, it is preferable that all the particles have the above oil absorption amount, but the filler does not necessarily have all the particles have a uniform oil absorption amount. A mixture may be used, and in the case of such a mixture of fillers having different oil absorptions, it is sufficient that 60% by weight or more of the entire filler has an oil absorption in the above range.

When the oil absorption of JIS K5101 of the filler is less than 80 ml / 100 g, the ink absorbency when used as recording paper is poor, and the coloring material in the ink cannot be secured on the surface of the coating layer. Tend to penetrate deep into the recording paper, and the coloring of the coloring material tends to deteriorate. On the other hand, if the amount exceeds 300 ml / 100 g, powder will fall off with the same amount of binder, and if the amount of binder required to prevent powder fall is used, the ink absorbency will decrease, which is not preferable.

Examples of the aqueous binder include water-soluble polymers such as polyvinyl alcohol, starch, oxidized starch, chaotic starch, casein, carboxymethyl cellulose, gelatin, hydroxyethyl cellulose, SBR latex, and MBR.
One or more water-dispersible polymers such as latex and vinyl acetate emulsion are used in combination.

The present inventor further investigated various properties of the water-based coating liquid at the time of coating, and found that the liquid viscosity at 30 ° C. of the water-based coating liquid was 60.
It was found that a recording paper having good ink jet recording characteristics can always be obtained stably in the range of up to 200 cps.

The viscosity in the present invention is measured by a B-type viscometer under the condition of 60 rotations / min. By changing the rotation speed, thixotropic property, dilatarant property and the like can be evaluated.

If the viscosity of the water-based coating liquid is less than 60 cps, the water-based coating liquid penetrates deep into the base paper, filling the voids that the base paper has for absorbing ink, resulting in Ink absorption may be deteriorated.

On the other hand, if it exceeds 200 cps, the viscosity is too high, which causes uneven coating, which is not preferable. Further, only the water in the water-based coating liquid may be absorbed by the base paper, and the strength of the surface layer may be reduced, which may cause powder drop or the like.

The viscosity of the water-based coating liquid as described above can be easily adjusted by the kind and combination of the filler and the binder, the ratio of their use, their respective concentrations, the total concentration and the like. In the present invention, generally, the use ratio of the silicon-containing filler and the binder is in the range of 3/1 to 1/1 (weight ratio), and the total solid content is in the range of about 3 to 70% by weight. A working solution is preferable.

If the amount of the binder is larger than the above range, the ink absorbency, particularly the initial absorption rate of the ink, decreases. This problem is more remarkable as the sizing degree of the base paper is higher and the grammage is lower within the range of the sizing degree of the base paper of 0 to 15 seconds. Further, if the content of the pigment is higher than the above range, the adhesive force is insufficient even when the thin coat layer is provided, and the problem of powder falling occurs. In particular, in the present invention using a base paper having a low size and a high basis weight, it is essential that the ratio of the pigment does not exceed the above range because the binder in the coating liquid is easily absorbed by the base paper during coating. is there. The problem of powder fallout becomes more serious as the size of the base paper becomes lower.

Furthermore, the viscosity of the water-based coating liquid has a close relationship with the coating speed. That is, the water-based coating liquid which is hydrophilic and comprises a filler having an oil absorption of 80 to 300 ml / 100 g according to JIS K5101 and a water-based binder often exhibits a thixotropic viscosity like a general coating liquid.

Therefore, if the coating speed is too fast, coating unevenness is likely to occur no matter how low the viscosity is, and if it is too slow, after coating,
It takes too long to scrape to a constant coating amount,
The water-based coating liquid permeates deep into the base paper and reduces ink absorbency, which is not preferable. Therefore, as a balance between the viscosity of the water-based coating liquid and the coating speed, when the viscosity is 60 to 200 cps, the coating speed of 60 to 200 m / min is suitable, and the travel speed is faster or slower than this. It is not preferable because the above-mentioned various problems occur.

As the coating machine used in the present invention, all conventionally known coating machines can be used, but coaters suitable for the present invention include an air knife coater and a bar coater.

The coating amount of the water-based coating liquid is 2 to 10 as the dry coating amount.
The range of g / m ² is suitable, and if it is less than 2 g / m ^2, it will not function as a coating layer. That is, the coating amount is 2 g / m
^{When it is} less than ^2, the ink that has collided with the surface of the recording paper bleeds along the fibers and the dot shape is disturbed, and at the same time, the dye penetrates deeply into the paper, and the color density of the image decreases. on the other hand,
If the coating amount exceeds 10 g / m ² , the merits of setting the sizing degree of the base paper to 0 to 15 seconds will disappear, and the fibrous substance of the base paper will not exist on the surface of the recording paper, resulting in ink absorption and color development. In addition to the unsatisfactory properties, the feel of the paper is reduced, and the problem of powder falling occurs.

In the present invention, after the aqueous coating liquid is applied under the conditions of the present invention, the recording paper is dried by a conventionally known drying method, for example, a hot air drying oven, a drying drum or the like to obtain a recording paper. In terms of process, surface smoothing may be performed by super calendaring.

As described above, the Steckigt sizing degree of the present invention is 0 to 15
You can obtain recording paper with a basis weight of 90 to 200 g / m ² per ^second .
More preferably, the Steckigt sizing degree is 0 to 10 seconds, optimally 0 to 5 seconds, and the basis weight is preferably 90 to
There is a range of 160g / m ² .

When the Steckigt sizing degree of the recording paper exceeds 15 seconds, the ink absorbability, particularly the initial absorbency is lowered, which is not preferable.

Also, when the basis weight of the recording paper is less than 90, the obtained recording paper has a weak stiffness and there is a problem in transportability, the ink absorption capacity of the recording paper is insufficient, and the printing part causes the clickling and the strike-through. Causes various problems as described above.

If the grammage exceeds 200 g / m ² , the resulting recording paper may have a problem of powder falling or curling.

(Operation / Effect) Since the recording paper of the present invention contains a large amount of a silicon-containing filler having a high ink absorption capacity in the surface layer of the recording paper, there is a high probability that the ink droplets will be captured and absorbed by the pigment. In addition, it is considered that ink bleeding and diffusion are suppressed, the dot shape is improved, and the color density is improved.

In addition, since the base paper itself has ink absorbency, the ink is quickly absorbed inside the recording paper, and even if different color inks adhere to the same location within a short time, the ink will run out or bleed. There is no phenomenon of sticking out, excellent color coloring, and there is no cockling or strikethrough in the printed part.

Further, in the range of the coating amount of the recording paper of the present invention, the fibrous substance on the surface of the base paper is not completely covered with the silicon-containing filler in the aqueous coating liquid, and the surface of the recording paper is not covered with the silicon-containing filler and fibers. It is in a state that substances are mixed. Therefore, not only it has sufficient characteristics as an ink jet recording paper, but also less powder is removed from the coating layer and it has a texture close to that of plain paper.

〔Example〕

Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the text, parts or% are based on weight unless otherwise specified.

Examples 1 to 5 and Comparative Examples 1 to 5 As a base paper, a low-size handmade sheet was adjusted to have the following basis weight, and an aqueous coating solution having the following composition was added to each of the base papers below. To a dry coating amount of 12
After drying at 0 ° C. for 5 minutes, recording sheets A to J of the invention and comparative examples were obtained.

Table 1 shows the basis weight of the base paper, the dry coating amount of the coating layer, the basis weight of the recording paper, and the Steckigt sizing degree of the recording paper.

(Coating liquid composition) Synthetic silica (Cyroid 620 manufactured by Fuji Devison Chemical) 1
0 part Polyvinyl alcohol (manufactured by PVA-117 Kuraray) 4 parts Water 100 parts Comparative Example 6 As an example of the above-mentioned recording paper (2), a dry coating of the above-mentioned coating liquid was carried out on a high-quality paper having a basis weight of 80 g / m ^2. Coating was performed so that the amount was 6 g / m ^2, and drying was performed in the same manner as above to obtain a recording paper K for comparison.
The recording paper obtained had a Steckigt sizing degree of 25 seconds.

The ink jet recording suitability of the above recording papers A to K is 1 in 1 mm.
Ink jet head with 128 nozzles at intervals of 6 nozzles is recorded with ink of the following composition using an ink jet printer having 4 colors of Y, M, C and Bk, and ink absorbency is recorded. , And resolution and color developability were evaluated.

Y (yellow) ink composition CI Direct Yellow 86 2 parts Glycerin 15 parts Diethylene glycol 15 parts Water 70 parts M (magenta) ink composition CI Acid Red 35 2 parts Glycerin 15 parts Diethylene glycol 15 parts Water 70 parts C (cyan) ink composition CI Direct Blue 199 2 parts Glycerin 15 parts Diethylene glycol 15 parts Water 70 parts Bk (black) Ink composition CI Food Black 2 2 parts Glycerin 15 parts Diethylene glycol 15 parts Water 70 parts Evaluation item (1) Dot concentration is JIS K7505 applied to micro dot Sakura Micro Densitometer PDM-5
(Konishi Roku Photo Industry Co., Ltd.) was used to measure the black dots.

(2) Ink absorbency is 128 at 16 nozzle intervals per 1 mm.
YMC ink jet recording head with two nozzles
Evaluation was performed using a bubble jet printer having four Bk colors. In the mixed color part of the two color inks of the recorded image, X is thicker than the single color part and feathering occurs in the mixed color part, and the blurred edge is Δ, and the mixed color part is as clear as the single color part. Those having an edge were marked with a circle.

(3) Dust is generated when the surface of the coat layer is touched with a finger, paper dust adheres to the finger, and when the recording paper is folded, the coat layer peels or cracks to generate paper dust. Those that were not were rated as ○.

(4) The strike-through was evaluated as × when the strike-through was confirmed when (2) was printed by the same printer, ◯ when it was not printed, and Δ when the median.

(5) When printed with the same printer as (2), the crocking is x when a scratch is generated on the surface of the recording paper that causes the head and the crocking, but no scrub is generated.
The cockling was visually confirmed, and the image quality was inferior, and the ones that were not noticeable were evaluated as ◯.

The evaluation results are shown in Table-2.

Examples 6 to 9 The recording papers L and M of the present invention and the base paper used in Example 3 were prepared in the same manner as in Example 1 except that the following composition was used on the base paper used in Example 1. Further, recording papers N and O of the present invention were obtained in the same manner except that the following composition was used. next,
Recording was carried out in the same manner as in Example 1 using these recording papers, and evaluation was performed. The results are shown in Table 3.

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-57-129779 (JP, A) JP-A-58-151291 (JP, A) JP-A-61-68288 (JP, A) JP-A-60- 63195 (JP, A) JP-A-62-162584 (JP, A)

Claims (11)

[Claims] 1. A fibrous base paper having a coating layer containing a silicon-containing pigment on the surface thereof, and the surface of the coating layer presents a mixed state of the silicon-containing pigment and the fibrous substance of the base paper. A recording paper which is characterized by further having a Steckigt sizing degree in the range of 0 to 15 seconds and a basis weight in the range of 90 to 200 g / m ² . 2. The recording paper according to claim 1, having a Steckigt sizing degree in the range of 0 to 10 seconds. 3. The recording paper according to claim 1, having a Steckigt sizing degree in the range of 0 to 5 seconds. 4. The recording paper according to claim 1, having a basis weight of 90 to 160 g / m ² . 5. The oil absorption of JIS K5101 of the silicon-containing pigment is in the range of 80 to 300 ml / 100 g.
Recording paper described in paragraph. 6. A silicon-containing pigment and an aqueous binder are 1/1
The recording paper according to claim 1, which is formed by coating a coating liquid containing the coating liquid in a weight ratio of 3/1. 7. An ink jet recording method in which an ink droplet is applied to a recording material by using an aqueous ink for recording, and the recording material contains a silicon-containing pigment on the surface of a fibrous base paper. A recording paper having a coating layer, wherein the surface of the coating layer is in a mixed state of a silicon-containing pigment and a fibrous substance of a base paper, further having a Steckigt sizing degree of 0 to 15 An ink jet recording method, wherein the inkjet recording method is in the range of seconds and the basis weight is in the range of 90 to 200 g / m ² . 8. The ink jet recording method according to claim 7, wherein the water-based ink contains a water-soluble dye. 9. The Stoeckigt sizing degree of the recording material is 0.
The ink jet recording method according to claim 7, which is in the range of 10 seconds. 10. The Stoeckigt sizing degree of the recording material is
The ink jet recording method according to claim 7, which is in the range of 0 to 5 seconds. 11. The ink jet recording method according to claim 7, wherein the recording material has a basis weight of 90 to 160 g / m ² .