JP2528487B2 - Method for producing pulp having improved filler yield and method for producing paper - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a pulp to which a filler is mechanically attached and a method for producing a paper using the pulp.

[Prior Art] In the production of printing paper or various base papers for processing, a filler is indispensable for improving the surface property, opacity, printability, etc. of the paper.

As a method for producing paper, there has been known a method in which pulp is beaten in advance and then a filler is added to prepare a papermaking raw material, and the paper is made into paper. However, since the surface charge of the filler in water is negative and it has the same polarity as that of the negative pulp, the coexisting system electrically repels each other and the fixing is not so good. . For this reason, a fixing agent or retention aid made of a cationic or anionic polymer is used as an internal additive to chemically fix the filler to the pulp to form a sheet on a paper machine. The fixing rate was poor and the fine filler easily escaped into white water. Moreover, as the papermaking speed increases, the yield of filler decreases, and if a large amount of a fixing agent or a retention improver is added to further improve the yield, the flocs of the fibers will increase and the texture of the paper will be poor. Therefore, there was a limit to the content of the filler that can remain in the paper.

[Means for Solving the Problems] The present inventors have studied how to effectively retain the filler in the paper without the above-mentioned drawbacks, and as a result, beaten the slurry in which the filler is added to the pulp to fibrillize the slurry. It has been found that such a problem can be solved by attaching a filler to the prepared pulp.

Examples of the pulp used in the present invention include NBKP, LBKP, hemp pulp and the like, and they are used in an unbeaten state or in a state in which they have not reached a predetermined beating degree. The present invention, when beating to a predetermined beating degree, is to be beaten in the state where the filler is mixed, whether the pulp has already been beaten at the start of the mixed beating, or is it not beaten yet? Although it depends on the degree of predetermined beating degree, the kind of filler, and the mixing ratio, unbeaten one is preferable from the viewpoint of the adhesion efficiency.

Next, as the filler added to the pulp, any one can be used as long as it is water-insoluble, for example, heavy calcium carbonate used for ordinary papermaking as an inorganic filler,
In addition to light calcium carbonate, titanium oxide, talc, kaolin, clay, diatomaceous earth, aluminum hydroxide and the like, ceramic raw material powders such as alumina and zirconia can be used. It is also possible to use one kind or a combination of two or more kinds of optional fillers depending on the use and performance of paper.

It is desirable to add about 10 to 100 parts by weight of these fillers to 100 parts by weight of pulp. If it is less than 10 parts by weight, a sufficient effect may not be obtained, and if it exceeds 100 parts by weight, the absolute amount of pulp is small and fibrillation becomes the limit state, so it is difficult to retain the increased filler. become.

The beating machine used in the present invention for beating the pulp and the filler together can be any beating machine that is usually used for beating pulp, and examples thereof include a disc refiner and a conical refiner. High-concentration viscous beating is suitable for promoting fibrillation of pulp.

When sheeting the pulp obtained in the present invention,
Although it is possible to lead it to a normal paper machine as it is for papermaking, it is possible to add a small amount of the above-mentioned fixing agent or retention improving agent in order to make the yield more efficient. Further, papermaking may be performed after adding a filler as a post-addition.

[Operation] In the mixed beating of the present invention, unlike the case where the beating degree is advanced with the pulp alone, the pulp preliminarily mixed with the filler undergoes the beating process, and therefore, the beating is not performed only by the blade of the beating machine. It will also be loosened by the fillers that are present at the same time. For this reason, when the fibrillation of the cellulose surface progresses, on the other hand, the filler is entangled with a large number of whisker-shaped small fibers generated by the fibrillation, and the filler retaining ability of the pulp is improved.

[Examples] Hereinafter, the present invention will be specifically described based on Examples.

(Example 1) To a pulp slurry composed of 100 parts by weight of unbeaten LBKP solid content, 40 parts by weight of a solid content of light calcium carbonate having an average particle diameter of 1.5 μm was added as a filler to dilute the concentration to 5%. The mixture was stirred to prepare a mixed slurry of pulp and filler. Then, the mixture was refined by mixing with a disc refiner to obtain 207 ml of freeness (Canadian standard freeness).

60g / m ² , 1 with TAPPI hand-made sheet machine using this raw material
00 g / m ² of handmade paper was prepared. The filler yield and paper quality test results of the obtained handmade paper are shown in Table 1.

(Comparative Example 1) For comparison, mixed beating was not performed, that is, freeness
A slurry of 40 parts by weight of the solid content of the light calcium carbonate used in Example 1 was added to 100 parts by weight of 180 ml of individually beaten LBKP solid content, the concentration was diluted to 5%, and the mixture was sufficiently stirred to complete 209 ml with freeness. I got the raw material.

A handmade paper was prepared from this raw material in the same manner as in Example 1, and the filler yield and paper quality test results of the obtained handmade paper are shown in Table 1.

(Example 2) To a pulp slurry consisting of 100 parts by weight of unbeaten LBKP solids was added a slurry of 50 parts by weight of solids of clay having an average particle diameter of 2.5 μm to dilute the concentration to 5%, and the mixture was sufficiently stirred to produce pulp And a mixed slurry of filler.

Next, the mixture was beaten with a disc refiner to obtain a finished material with a freeness of 203 ml.

Using this raw material, 50 g / m ² of handmade paper was prepared with a TAPPI handmade sheet machine. The filler yield and paper quality test results of the obtained handmade paper are shown in Table 2.

(Example 3) A trace amount of the cationic acrylamide retention improver was added to the finished material having a freeness of 203 ml obtained in Example 2,
After thorough stirring, 230 ml of raw material was obtained as a freeness. Using this raw material, a handmade paper was prepared in the same manner as in Example 2, and the filler yield and paper quality test results of the obtained handmade paper are shown in Table 2.
Shown in the table.

(Comparative Example 2) For comparison, a slurry of 50 parts by weight of the solid content of the clay used in Example 2 was added to 100 parts by weight of the individual beating LBKP solid content of 180 ml of freeness without mixed beating to obtain a concentration of 5%.
The mixture was diluted with and thoroughly stirred to obtain a finished material with a freeness of 200 ml. A handmade paper was prepared from this raw material in the same manner as in Example 2.

(Comparative Example 3) A trace amount of the cationic acrylamide retention improver was added to the finished raw material having a freeness of 200 ml obtained in Comparative Example 2,
After sufficiently stirring, 234 ml of freeness of raw material was obtained. A handmade paper was prepared from this raw material in the same manner as in Example 3. The filler yield and paper quality test results for the handmade papers of Comparative Examples 2 and 3 are shown in Table 2.

(Example 4) To a pulp slurry consisting of 100 parts by weight of LBKP which had been beaten to a freeness of 450 ml, 40 parts by weight of light calcium carbonate having an average particle diameter of 1.5 μm was added to dilute it to a concentration of 5%, and sufficiently stirred. A mixed slurry of pulp and filler was obtained. Then, mixed beating was carried out in the same manner as in Example 1 to obtain a finished material having a freeness of 205 ml, and handmade paper was prepared. The filler yield and paper quality test results for the obtained handmade paper are shown in Table 3.

[Effects of the Invention] In the present invention, a slurry of pulp and filler is mixed and beaten to generate a special physical relationship between them,
A high yield of filler can be realized. Moreover, the obtained pulp can be directly used for papermaking, and a paper with a high filler yield can be produced without deteriorating the formation of the paper.

Claims (4)

(57) [Claims] 1. A pulp having an improved filler yield, characterized in that the filler is adhered to the pulp by adding a filler to a beating or unbeaten chemical pulp slurry in advance and performing mixed beating to a predetermined beating degree. Production method. 2. The filler is heavy calcium carbonate, light calcium carbonate, titanium oxide, talc, kaolin, clay,
The method for producing pulp according to claim 1, which is one kind or a combination of two or more kinds selected from diatomaceous earth, aluminum hydroxide, alumina, and zirconia. 3. The amount of filler added is 10 per 100 parts by weight of pulp.
The method for producing pulp according to claims 1 and 2, wherein the pulp content is from 100 to 100 parts by weight. 4. A method in which a filler is added in advance to a beaten or unbeaten chemical pulp slurry and mixed and beaten to a predetermined beating degree to allow the filler to adhere to the pulp, and then the pulp slurry is made into paper. To make paper.