JP2894952B2 - Neutral papermaking - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a neutral papermaking in which good sizing is prevented from deteriorating.

[0002]

2. Description of the Related Art Sizing agents are usually used to impart water resistance to paper and prevent recording bleeding. In conventional acidic papermaking, the paper is treated with a rosin-based sizing agent or the like, and treated with aluminum sulfate as a fixing agent to give a desired sizing degree. However, when aluminum sulfate is used, a dehydration reaction occurs with the lapse of time due to the presence of a sulfate group, which causes a problem of so-called paper deterioration such as yellowing of paper and reduction in strength. The effect of the rosin-based sizing agent, which attempts to neutralize the pulp slurry for the purpose of preventing paper deterioration, rapidly decreases at pH 6 or higher as shown in FIG. Can not.

On the other hand, there is a so-called neutral papermaking method for preventing deterioration. In neutral papermaking, a neutral sizing agent such as alkyl ketene dimer or alkenyl succinic anhydride is used as a sizing agent, a cationic polymer is used as a retention aid, and calcium carbonate is used as a filler. In neutral papermaking technology, paper extraction PH
Is about 8.0 to 9.5, but since the pulp slurry PH at the time of paper making is in the same alkaline region as the extracted PH, pitch and slime are generated, and furthermore, a neutral sizing agent and the like in the paper machine system. There were many occurrences of dirt and the like, which was regarded as an operational problem.

To solve these problems, Japanese Patent Laid-Open No.
-73692 proposes the following.

In a system containing a filler, aluminum sulfate, a hydrophobized modified rosin emulsion-based sizing agent and a water-soluble alkaline salt, the pulp slurry at the time of papermaking is adjusted to pH
The pH is adjusted to 6.5 to 7.5, and an alkali metal salt of an acid having a pKa of 5 to 14 is applied, and the cold water extraction PH of the coated paper is adjusted to 7.5 to 9.0. .

However, in the above-mentioned method, since the pulp slurry PH during papermaking is as low as 6.5 to 7.5, it is inferior to the so-called neutral papermaking in terms of paper deterioration, which is a characteristic of neutral papermaking. There were drawbacks.

[0007]

The present inventors have found that the deterioration of paper is equal to or more than that of so-called neutral papermaking,
In addition, as a result of intensive studies on paper and a method for producing the same that produce less pitch and slime and have good operability as a result, the pulp slurry PH during papermaking was reduced in a system using aluminum sulfate and an anionic neutral rosin emulsion sizing agent in combination. It was found that good results were obtained by adjusting with a water-soluble alkaline salt so as to be in the range of 6.5 to 8.5, and the present invention was reached.

[0008]

According to the present invention, there is provided an alkaline salt-free filler, at least one filler selected from the group consisting of kaolinite, illite or talc, and aluminum sulfate, anionic neutral rosin. The pH of the papermaking pulp slurry containing an emulsion-based sizing agent and a water-soluble alkaline salt is 6.5 to 8.5, and sometimes 7.5 to 8.5, depending on the water-soluble alkaline salt.
Achieved by paper characterized by being adjusted to 5.

In the present invention, the addition of aluminum sulfate to the pulp slurry for papermaking prevents generation of pitch and slime, and the use of an anionic neutral rosin emulsion sizing agent makes the pulp slurry for papermaking neutral and neutral. In the weakly alkaline region, it was possible to completely solve the problem of so-called paper deterioration such as good sizing property development and yellowing and strength reduction of paper.

Regarding the deterioration of paper, as shown in FIG.
The correlation is substantially recognized with the extracted pH of the paper, and when the pH is 6 or less, the deterioration is remarkable. In order to prevent deterioration, it is necessary that PH is 6.5 or more.
It is desirable that H is 7.0 or more. Further, the paper proposed in the above-mentioned JP-A-6-73692 raises the extraction pH of the paper by coating with an alkali metal salt, but has the disadvantage that deterioration is more likely to occur than so-called neutral paper. There is. The reason is that the pulp slurry PH at the time of paper making is 6.5.
７7.5, which is considered to be lower than that of pulp slurry PH for so-called neutral paper. In addition, as previously mentioned in FIG. 1, the conventional rosin-based sizing agent rapidly decreases in sizing degree at pH of 6 or more and cannot be put to practical use. Next, even when a hydrophobic modified rosin emulsion-based sizing agent (example of use, "Size Pine NTS" manufactured by Arakawa Chemical Industries, Ltd.) proposed in JP-A-6-73692 is used.
If it is 7.5 or more, the sizing degree expression is not sufficient. The present inventors have conducted intensive studies on the sizing agent and found that the pH was 7.5.
It has been found that anionic neutral rosin emulsion-based sizing agents can be used from the viewpoint that the expression of the degree of sizing is sufficient and that they can be used in combination with aluminum sulfate.

[0011] Even with an anionic neutral rosin emulsion sizing agent, if the pH is 9 or more, the sizing degree is reduced, and it cannot be put to practical use. Therefore, in the present invention, the pH of the pulp slurry at the time of papermaking is set to 6.5 to 8.5, preferably 7.0 to 8.5.

Since the pH of the pulp slurry for papermaking is adjusted to 6.5 to 8.5, and sometimes 7.5 to 8.5 with a water-soluble alkaline salt, the pH of the pulp slurry, such as calcium carbonate conventionally used for neutral papermaking, is adjusted. No alkaline salt filler is used.

As the filler, kaolinite, illite or talc is used alone or as a mixture of two or more. In the present invention, pH adjustment is required, and kaolinite, illite or talc is used. In addition,
The filler is usually added to the paper in an amount of 1 to 30% by weight.

The anionic neutral rosin emulsion-based sizing agent used as a sizing agent in the present invention is used as a usual paper-making chemical, and the amount of addition is 0.1.
0.5-0.7% is suitable.

In the present invention, aluminum sulfate is used from the operational viewpoint of preventing the generation of pitch and slime. The amount of aluminum sulfate used is 0.1 to
It is 5.0%, preferably 0.5 to 3.0%.
In the present invention, aluminum sulfate is used, and kaolinite, illite or talc is used alone or as a mixture of two or more fillers.
Therefore, the pulp slurry PH is adjusted to 6.5 to 8.5 with a water-soluble alkaline salt, and in some cases 7.5 to 8.5.
Adjust to 8.5.

Examples of the water-soluble alkaline salt include hydroxides such as sodium hydroxide and calcium hydroxide, silicates such as sodium silicate, carbonates such as sodium carbonate, potassium carbonate and sodium hydrogen carbonate, and hydrogen carbonate. Salts, phosphates such as sodium phosphate and disodium hydrogen phosphate and hydrogen phosphate.

The pulp used in the present invention is a chemical pulp,
It is a recycled pulp, and even when mechanical pulp is used, paper with little deterioration can be obtained. As other internal additives, a cationized starch, a retention aid, a dye, a paper strength enhancer, an antifoaming agent and the like can be appropriately added.

The paper of the present invention may be used for general office paper, writing paper,
It is used as printing paper, various coating base papers, output paper for computers, and transfer paper for electrophotography.

[0019]

As described above in detail, although the paper of the present invention is a size paper using aluminum sulfate, the pH of the pulp slurry at the time of papermaking is adjusted to 6.5 to 8.5. Therefore, it is excellent in preventing deterioration of the paper and developing the degree of sizing, and also generates little pitch and slime in operation.

[0020]

The present invention will be described in more detail with reference to the following examples, but it should not be construed that the invention is limited thereto. In the examples,% indicates pulp weight%. In addition, cold water extraction PH is measured according to JIS-P8133.

Example 1 90 parts by weight of LBKP (csf 400 ml), 10 parts by weight of kaolinite, 2.0% of aluminum sulfate, anionic neutral rosin emulsion sizing agent (CC-166K,
0.3%, manufactured by Nippon PMC Co., Ltd.), and an aqueous sodium hydroxide solution was added to the pulp slurry.
Was adjusted to 7.5. Papermaking was performed using the pulp slurry for papermaking to produce a high-quality paper of 64.0 g / m ² . When producing high quality paper, an aqueous solution of starch oxide was applied by a size press so as to have an application amount of about 2 g / m ² . The cold water extraction PH of this paper was 7.6. In addition, Table 1 shows the degree of Stigecht sizing of the paper, the degree of change in processing with a fade meter, and the bending strength.

[0022]

Comparative Example 1 Example 1 was repeated except that no aqueous sodium hydroxide solution was added.
Fine paper was obtained in the same manner as described above. At this time, the papermaking pulp slurry PH was 5.0, and the cold water extraction pH of the paper was 5.5. Table 1 shows the results of evaluation of this paper in the same manner as in Example 1.
It was shown to.

Comparative Example 2 A paper was made using the pulp slurry for papermaking of Example 1 to which no aqueous sodium hydroxide solution was added, and about 2 g of an aqueous solution of oxidized starch containing sodium carbonate was obtained by size pressing.
/ M ² . At this time, the pH of the pulp slurry was 5.0, and the pH of the paper extracted with cold water was 7.0.
It was 3. The results of evaluating this paper in the same manner as in Example 1 are shown in Table 1.

Comparative Example 3 87 parts by weight of LBKP (csf 400 ml), 13 parts by weight of calcium carbonate, 0.5% of anionic neutral rosin emulsion-based sizing agent (CC-166K, manufactured by Nippon PMC)
, And woodfree paper was produced in the same manner as in Example 1. The pulp slurry PH at this time was 8.8, and the cold water extraction PH of this paper was 8.6. The results of evaluating this paper in the same manner as in Example 1 are shown in Table 1.

[0026]

[Table 1] * 1 According to JIS P8122.

* 2 Difference in yellowness before and after 50 hours of treatment with a fade meter.

The yellowness is measured with a spectrophotometer (manufactured by Nippon Denshoku Co., Ltd.).

* 3 According to JIS P8115.

* 4: No occurrence of pitch or slime in the paper machine system was indicated by ○, and occurrence of slime was observed by X.

* 5: No occurrence of dryer stain was observed, and x was observed.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between pH and sizing degree of a pulp slurry for papermaking.

FIG. 2 is a graph showing a relationship between paper extraction PH and paper deterioration.

Claims (3)

(57) [Claims] 1. An alkaline salt-free filler, at least one filler selected from the group consisting of kaolinite, illite or talc, aluminum sulfate, anionic neutral rosin emulsion-based sizing agent and water-soluble alkaline A paper characterized in that it is a neutral paper that is made with a paper pulp slurry containing salt. 2. A papermaking pulp slurry having a pH of 7.5 to 7.5.
2. The paper according to claim 1, wherein the paper is 8.5. 3. The paper according to claim 1, which is used as an electrophotographic transfer paper.