JPH06235188A - Paper making method - Google Patents

Abstract

PURPOSE:To produce a rigid paper having excellent smoothness and opacity. CONSTITUTION:A filler having an average particle diameter of 0.1-5.0mum is mixed with a softwood pulp having a water retention value of 2.0-3.0 together with a fixing agent, the mixture is mixed with a hardwood pulp having a water retention value of 1.1-1.4 and a paper is formed from the pulp mixture. A paper having especially excellent quality can be produced by mixing the softwood pulp (N) and the hardwood pulp (L) at a weight ratio (N/L) of 5/95 to 20/80. Since the produced paper has excellent rigidity, smoothness and opacity, it has excellent workability in printing and gives excellent printed letter quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a paper which is rigid and has excellent smoothness and opacity.

[0002]

2. Description of the Related Art Normally, the standard of paper is defined by basis weight, but the thickness is often more important as a characteristic of printing paper and information paper. In particular, with the automation of printing machines, printers, etc., sufficient rigidity may be required when it is required to improve workability when feeding paper to the machine and runnability of the paper inside the machine. First of all, it is required to supply the paper with the thickness suitable for the machine or device. In doing so, of course, it is expected that the printing or print-related quality characteristics of the original application, such as smoothness, will remain unchanged or even improved. In addition, along with the trend of lowering the basis weight of paper, high opacity is also required at the same time.

In order to meet the above requirements for paper thickness, technical measures such as reducing the beating degree and lightening the pressure applied by a press are first taken, but the filler yield is reduced accordingly. There is a limit to the countermeasures because stains occur on the press roll, the smoothness decreases, the strength decreases, and the like. Therefore, it is unavoidable to manufacture paper with a basis weight of more than the standard. Recently, however, the review is required from the viewpoint of protecting wood resources.

On the other hand, attempts have been made to improve the paper manufacturing method to actively manufacture low-density paper. They include a method disclosed in Japanese Patent Laid-Open No. 59-43199, in which paper is made to contain fibers crushed by being compressed when wet, as disclosed in Japanese Laid-Open Patent Publication No. 51-132822. A method of adding expandable microspheres to pulp,
JP-B-55-47385, JP-A-58-2400
No. 0, JP-A-58-197400, etc., there is a method of mixing and using lightly beaten pulp and beaten pulp. Also, as a means for improving the opacity of paper, attempts have been made to use high refractive index pigments and increase the filler content.

[0005]

Various studies have been conducted in order to produce a paper that is rigid and has excellent smoothness and opacity. As a result, the method of containing the fibers crushed by the compression treatment and the method of incorporating the expandable microspheres into the paper can obtain a paper having a low density but not a paper having sufficient rigidity and smoothness. It became clear that I could not. The method of mixing and using a pulp that has been beaten gently and a pulp that has been beaten is also a method in which the water retention of the pulp that is beaten is too low (Japanese Patent Publication No. Sho 55-47385) under the conditions disclosed in the above publications, or the like. Is too high (JP-A-58-24000,
Therefore, even if a paper having a low density and excellent rigidity can be produced, it was not sufficient to obtain a paper having excellent smoothness. Further, in order to improve the opacity, it was tried to change the kind and the addition amount of the filler, but it was unavoidable that the strength and the rigidity were lowered. That is, an object of the present invention is to provide a method for producing paper that is rigid and has excellent smoothness and opacity.

[0006]

[Means for Solving the Problems] In order to solve the above problems, as a result of trying various methods, as a result, a method of mixing and using a pulp that has been softly beaten and a pulp that has been beaten has been significantly changed. Because it can be carried out without
It turned out to be advantageous. Therefore, in order to improve the lack of excellent smoothness, which is a drawback of the conventional method, and to focus on the improvement of opacity, a detailed study will be conducted focusing on the swelling property of the pulp fiber and the dispersibility of the filler. went.

As a result of the above, the average particle diameter is 0.1 to 5.0 μm.
After mixing m filler and softwood pulp (N) having a water retention of 2.0 to 3.0 with a fixing agent, the water retention is 1.1 to 1.4.
It was clarified that a paper with high rigidity, smoothness and opacity can be obtained by mixing with the hardwood pulp of No. 3 and papermaking. Also, softwood pulp (N) and hardwood pulp (L)
When mixed so that the weight ratio (N / L) of the mixture is 5/95 to 20/80, or the filler (P) having an average particle size of 0.1 to 5.0 μm and the water retention of 2.0 to 3. The mixing ratio (P / N) of 0 softwood pulp (N) is 1/2 or more by weight 5 /
It has been revealed that the case of 1 or less, or any case thereof is particularly preferable.

The filler of the present invention has an average particle size of 0.
1 to 5.0 μm talc, clay, kaolin, calcined kaolin, titanium dioxide, precipitated calcium carbonate, ground calcium carbonate, calcium sulfate, barium sulfate, aluminum hydroxide, aluminum silicate, calcium silicate, plastic pigment, etc. Usually, fillers that can be used in paper can be used alone or in combination. When the average particle size is less than 0.1 μm or more than 5.0 μm, sufficient opacity cannot be obtained.

The average particle size in the present invention means the particle size distribution obtained by dispersing an aqueous dispersion of filler for 5 minutes with an ultrasonic disperser and then using a light transmission type particle size distribution measuring device (SKN type, manufactured by Seishin Enterprise Co., Ltd.). Cumulative weight percentage of 5 determined from the curve
The diameter of the particles corresponds to 0%.

Examples of the fixing agent for the filler include cationic polyacrylamide, polyethyleneimine, polyamidoamine, polyamino polyamide polyamide epichlorohydrin, cationic starch, cationic polyelectrolytes such as cationic guar gum, sulfuric acid bands, aluminum chloride, PAC and the like. Inorganic cationic substances can be used. Further, an anionic substance or an amphoteric polyelectrolyte which forms a complex with a cationic polyelectrolyte such as anionic polyacrylamide, colloidal silica or bentonite can be used in combination with the cationic substance.

Filler (P) having an average particle size of 0.1 to 5.0 μm and softwood pulp (N) having a water retention of 2.0 to 3.0
The mixing ratio (P / N) is preferably 1/2 to 5/1 by weight. The range of the mixing ratio is limited by the (N / L) ratio and the target filler content in the paper, but is usually 1
If it is less than / 2, sufficient opacity and rigidity cannot be obtained, and if it exceeds 5/1, the effect of improving opacity tends to decrease. As a means for mixing the filler with the fixing agent into the softwood pulp, a method of adding and mixing the filler and the fixing agent to a pulp slurry having a concentration of several percent in a chest or a tank while stirring and continuously adding and mixing using an in-line mixer, etc. How to do it is available.

In the present invention, water retention is taken as an index of fiber swelling property and beating degree. The freeness is preferable from the viewpoint of ease of measurement, but the freeness is considered to be unsuitable as a method for defining the swelling property of the fibers because it is easily affected by the fiber morphology and chemical composition of the pulp.

The water retention is a value measured according to TAPPI standard method UM256, and after centrifugation under predetermined conditions,
The weight of water retained on the wet pulp (W) was expressed as a ratio (W / P) to the dry weight of pulp. However,
In the present invention, the centrifugation conditions include a temperature of 21 ± 3 ° C. and a temperature of 30 ° C.
00g (g = gravitational acceleration) for 15 minutes.

The water retention of pulp is 2.0 to 3.0 for softwood pulp and 1.1 to for hardwood pulp.
It is 1.4. If the water retention of the softwood pulp is less than 2.0, good rigidity cannot be obtained because the reinforcing effect of the interfiber bond is insufficient, and the effect of improving the opacity due to the addition of the filler is small and 3.0 When it exceeds, the shrinkage at the time of drying becomes large and the smoothness is lowered. When the water retention of the hardwood pulp is less than 1.1, sufficient flexibility cannot be obtained due to lack of flexibility of the fiber, and the rigidity becomes low. Is decreased (the density is increased), the rigidity is decreased and the smoothness is decreased, which is not preferable.

In the present invention, the means for controlling the water retention of pulp is usually equipment used for beating pulp, that is, beaters, conical refiners, disc refiners, etc., or JP-A-56-100801. The method of treating the pulp under high pressure with a homogenizer can be used. For softwood pulp, it is particularly preferable to select a device or blade type capable of viscous beating.

Examples of the pulp used in the paper of the present invention include kraft pulp, sulfite pulp, chemithermo-mechanical pulp and the like. The mixing ratio (N / L) of the softwood pulp and the hardwood pulp is preferably in the range of 5/95 to 20/80. If it is less than 5/95, sufficient rigidity cannot be obtained, and 2
If it is larger than 0/80, the shrinkage during drying becomes large, so that good smoothness cannot be obtained.

The paper of the present invention is usually used in papermaking,
A dye, a filler, a sizing agent, a fixing agent, a dry paper strengthening agent and the like are contained as necessary. Furthermore, it is also possible to apply starch, polyvinyl alcohol, or the like to the paper surface by a size press or the like. It is also possible to provide a coating layer on the surface depending on the application. In addition, as a coating device at that time, an air knife coater, a gravure coater, a curtain coater, a die coater, a blade coater, or the like is used.

The rigid, smooth and excellent opaque paper according to the present invention can be used as an uncoated printing paper, an electrophotographic transfer paper, a thermal transfer image-receiving paper, or a printing coated paper. It is used as a base paper for thermal recording paper, ink jet paper, magnetic recording paper, photographic printing paper, etc.

[0019]

The filler of the present invention having an average particle diameter of 0.1 to 5.0 μm and the softwood pulp having a water retention of 2.0 to 3.0 are mixed with a fixing agent, and then the water retention of 1.1 to 1.4 is obtained. According to the manufacturing method of mixing with hardwood pulp of No. 3, and making paper, a rigid paper having excellent smoothness and opacity can be obtained.

[0020]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples. The present invention is not limited to the examples. All parts and% in the following are by weight. The value showing the coating amount is the weight after drying unless otherwise specified.

Example 1 A double disc refiner having a water retention of 2.0 and 2.6.
In addition, softwood kraft pulp (NBKP) beaten with three levels of 3.0 was added to precipitated calcium carbonate with an average particle size of 1.0 μm (TP121, manufactured by Okutama Kogyo Co., Ltd.).
In an amount such that the weight ratio to NBKP is 1.5, and 0.5 to the total weight of pulp and filler is added.
% Equivalent amount of cationic starch (Kate F, manufactured by Oji National Co., Ltd.) was added and mixed to obtain an aggregate of pulp and filler. Next, the hardwood kraft pulp (LBKP) beaten to a water retention of 1.2 has a weight ratio (N / L) of 10 / NBKP.
The mixture was mixed so as to have a mixing ratio of 90, and pulps having three kinds of formulations were prepared.

Next, an alkyl ketene dimer sizing agent (HACON 11-) was added to 100 parts of each pulp.
2, Dick Hercules Co., Ltd.) 0.1 parts, and cationic starch (Kate F, Oji National Co., Ltd.) 0.7 parts were added, and a basis weight of 64 g /
m ² of paper was produced. The paper dried with a multi-cylinder dryer was size-pressed with a 3% aqueous solution of oxidized starch, dried, and then machine calendered. These samples
Samples 1-2, in order of decreasing water retention of NBKP,
These are 1-3 and 1-4.

Comparative Example 1 In Example 1, the water retention of NBKP was 1.9 and 3.
Papers were obtained in the same manner except that the levels were changed to 1 and 2 levels. Samples 1-1 and 1-
Set to 5. Table 1 summarizes the results of the measured rigidity, smoothness, and opacity of the above samples.

Note that N / L in Tables 1 to 6 are NBKP and L
It is a weight ratio of BKP, and P / N is a weight ratio of filler and pulp. Stiffness is the value of Clark stiffness measured according to JIS P 8143. To obtain good runnability in an electrophotographic copying machine or printer, in the case of a paper having a basis weight of 64 g / m ² , the longitudinal direction is 53.0 cm. ^3/100 or more, more preferably it requires 56cm ^3/100 or more. Smoothness conforms to British Standard Method 6563, measuring pressure 10 kg /
cm ² is the smoothness measured by Parker Print Surf (manufactured by Lorenzen Co., Ltd.) under the condition of using a hard material as the pressure plate, and the smaller the value (μm), the smoother. In order to obtain good printing and printability, the thickness is required to be 5.5 μm or less, and more preferably 5.3 μm or less. The opacity is a value measured by a Hunter whiteness tester according to JIS P 8138, and in order to have good opacity, it is required to be 82% or more, and more preferably 85% or more. There is.

[0025]

[Table 1]

From the results shown in Table 1, the water retention of NBKP was 2.
It is clear that in the case of 0 to 3.0, a paper having good rigidity, smoothness and opacity can be obtained. It can be seen that when the water retention value is less than 2.0, a paper excellent in rigidity and opacity cannot be obtained, and when it exceeds 3.0, the smoothness is deteriorated.

Example 2 In Example 1, the water retention of NBKP was set to 2.6 and LBKP was used.
Paper was manufactured in the same manner except that the water retention was changed to two levels of 1.1 and 1.4. Samples 2-2 and 2-3 are prepared in order of decreasing water retention.
And

Comparative Example 2 In Example 2, the water retention of LBKP was 1.0 and 1.
Paper was obtained in the same manner except that the level was changed to 2 of 5. These samples are referred to as samples 2-1 and 2-4. The above results are summarized in Table 2.

[0029]

[Table 2]

From Table 2, the water retention of LBKP is 1.1 to.
It can be seen that in the case of 1.4, a paper excellent in rigidity and smoothness can be obtained. On the other hand, if it is less than 1.1, the flexibility of the fiber is insufficient and sufficient strength cannot be obtained, so the rigidity becomes low, and if it exceeds 1.4, the rigidity decreases and the smoothness also decreases. Is allowed to do.

Example 3 In Example 1, NBKP having a water retention of 2.6 and water retention of 1.
The weight ratio (N / L) of 2 LBKP is 3/97, 5
/ 95, 20/80 and 30/70, and the same method except that the amounts of the precipitated calcium carbonate and the cationic starch added were changed so that the filler content was the same as in Example 1. Got the paper in. Samples 3-1, 3-2, and 3-3 are prepared in order of decreasing weight ratio.
And 3-4. The above results are summarized in Table 3.

[0032]

[Table 3]

From the results in Table 3, the weight ratio (N / L) of NBKP and LBKP is required to be in the range of 5/95 to 20/80 in order to obtain a paper excellent in rigidity and smoothness, 5 /
When it is less than 95, sufficient rigidity cannot be obtained, and when it is more than 20/80, shrinkage at the time of drying becomes large, so that it is apparent that good smoothness cannot be obtained. The weight ratio of the filler to NBKP in this case is in the range of 1/2 to 5/1.

Example 4 In Example 1, the water retention of NBKP was set to 2.6, and LBKP was used.
Has a water retention of 1.2, (N / L) of 5/95, and weight ratios (P / N) of precipitated calcium carbonate (P) and NBKP (N) of 1/3, 1/2, 2 0.0, 5.0 and 6.
The amount of precipitated calcium carbonate is adjusted so that the filler content is 30%, and the amount of cationic starch added to the pulp is also adjusted so that the amount of cationic calcium added is constant. Paper was manufactured in the same manner except that Samples 4-1, 4-2, 4-3, 4-4 and 4-are prepared in order of decreasing weight ratio.
Set to 5. The above results are summarized in Table 4.

[0035]

[Table 4]

From Table 4, the average particle diameter is 0.1 to 5.0 μm.
The mixing ratio (P / N) of the filler (P) and the softwood pulp (N) having a water retention of 2.0 to 3.0 is 1/2 or more by weight 5 /
When it is 1 or less, a paper excellent in rigidity and opacity can be obtained, and (P / N) is less than 1/2 or 5/1.
It is clear that the rigidity and the opacity decrease when the value exceeds.

Example 5 In Example 1, the average particle diameter of the filler is 0.1 and 5.0.
Using different settling calcium carbonate in μm and 2 levels, N
Paper was manufactured by the same method except that the water retention of BKP was changed to 2.6. Samples 5-2 and 5-3 were prepared in order of decreasing average particle size of calcium carbonate.
And

Comparative Example 4 In Example 5, the average particle size of calcium carbonate was adjusted to 0.
Paper was obtained by the same method except that the levels were changed to two levels of 05 and 8.0 μm. These samples are referred to as samples 5-1 and 5-4, respectively. Table 5 is a summary of the above results.
Shown in.

[0039]

[Table 5]

By comparing Table 5 with Table 1, it is clear that by using calcium carbonate having an average particle size of 0.1 to 5.0 μm, a paper having excellent rigidity and opacity can be obtained. is there.

Comparative Example 5 Paper was manufactured in the same manner as in Example 1 except that NBKP had a water retention of 2.6 and no cationic starch for fixing the filler was added. This sample is referred to as sample 6-1.

Comparative Example 6 In Example 1, NBKP had a water retention of 2.6 and a filler of NBKP.
Paper was all made in the same manner except that it was added to the mixed pulp of BKP and LBKP. This sample is referred to as sample 6-2.

[0043]

[Table 6]

Comparing Table 6 with Samples 1-3 in Table 1, after the filler and NBKP were mixed with the fixing agent, the production method of the present invention in which LBKP was mixed and papermaking was performed after the fixing agent was not added or the filler was mixed. It can be seen that the method of adding to the pulp gives a paper having excellent rigidity, smoothness and opacity.

[0045]

From the above, the method for producing the paper of the present invention, that is, the filler having an average particle diameter of 0.1 to 5.0 μm and the water retention of 2.0.
After the softwood pulp of ~ 3.0 is mixed with the fixing agent, it is mixed with the hardwood pulp having the water retention of 1.1-1.4 to make a paper, and a rigid, smooth and excellent opaque paper is obtained. To be In addition, these papers have excellent rigidity, smoothness, and opacity, and at the same time, have good runnability in an electrophotographic copying machine,
The printability with a light printing machine and the print quality with an inkjet printer were also good.

Claims (3)

[Claims] 1. A filler having an average particle size of 0.1 to 5.0 μm and a softwood pulp having a water retention of 2.0 to 3.0 are mixed with a fixing agent, and then the water retention is 1.1 to 1.4. A method for producing paper, which comprises mixing with the above hardwood pulp to produce paper. 2. The method for producing paper according to claim 1, wherein the weight ratio (N / L) of the softwood pulp (N) and the hardwood pulp (L) is 5/95 to 20/80. 3. The weight ratio (P / N) of the filler (P) and the softwood pulp (N) having an average particle diameter of 0.1 to 5.0 μm is 1
It is / 2-5 / 1, The manufacturing method of the paper of Claim 1 or 2 characterized by the above-mentioned.