JP3483220B2 - Paper coating method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating paper, and more particularly to a method for obtaining a base paper for newsprint which does not adhere to or wind around an offset rotary press and does not generate paper dust.

[0002]

2. Description of the Related Art In recent years, the weight of base paper used in newspapers and weekly magazines has been decreasing, and the proportion of waste paper has been increasing. Thus, such a base paper is often coated with a water-soluble polymer such as starch or polyvinyl alcohol so as to be suitable for printing, particularly high-speed printing.

[0003]

However, such coated paper may generate paper dust during printing to deteriorate the appearance of the printed matter, or paper dust may accumulate between rolls of the printing machine, causing paper breakage. I have something to do. Further, since the paper becomes sticky due to the dampening water at the time of offset printing and sticking to each other or to the roll occurs, there is room for improvement.

[0004]

However, as a result of intensive studies to solve the above problem, the present inventor has found that 50 to 100% by weight of the pulp composition is a high yield pulp on a base paper.
It consists composition of starch and dialdehyde, dialdehyde
It was found that the object can be achieved by blending 0.5 to 30% by weight with respect to starch and clear-coating a starch- based aqueous solution having a pH of 4 to 8 to complete the present invention. Hereinafter, the present invention will be specifically described.

[0005] base paper as an object of the present invention, newsprint, paperboard, medium-quality paper, medium-quality coated base paper, tissue, paper towels, a 50 to 100% by weight of high-yield pulp which is widely used in such exposure It is the one contained.

The high-yield pulp includes, for example, stone ground pulp, pressure stone ground pulp, refiner ground pulp, thermomechanical pulp, chemithermomechanical pulp, chemimechanical pulp, bleached chemithermomechanical pulp, semichemical pulp, and the like. , A pulp mainly containing so-called mechanical treatment containing lignin produced by these modified methods, or deinked pulp or recycled pulp containing these.

Starch in the coating solution used in the present invention
Is used.

Examples of starch include raw starch (corn starch, potato starch, sweet potato starch, wheat starch, kissava starch, sago starch, tapioca starch, sorghum starch, rice starch, bean starch, kudzu starch, bracken starch, lotus starch,
Physically modified starch (α-starch, fractionated amylose, heat-moisture treated starch, etc.): Enzyme-modified starch (hydrolyzed dextrin, enzyme-degraded dextrin, amylose, etc.): Chemically-modified starch (acid-treated starch, hypochlorous acid) Acid-oxidized starch, dialdehyde starch, etc.): chemically modified starch derivatives (esterified starch, etherified starch, cationized starch, cross-linked starch, etc.) and the like, and mixtures of two or more thereof are used.

Among the chemically modified starch derivatives, esterified starch includes acetic acid esterified starch, succinic acid esterified starch, nitrate esterified starch,
Etherified starches such as phosphoric acid esterified starch, urea phosphoric acid esterified starch, xanthogenic acid esterified starch, acetoacetic acid esterified starch, etc. are allyl etherified starch, methyl etherified starch, carboxymethyl etherified starch, hydroxyethyl. Examples of the cationized starch such as etherified starch and hydroxypropyl etherified starch include a reaction product of starch and 2-diethylaminoethyl chloride and a reaction product of starch and 2,3-epoxypropyltrimethylammonium chloride.

[0010]

Examples of the dialdehyde include glyoxal, malonaldehyde, succinaldehyde, glutaraldehyde, adipine aldehyde, heptanedial and the like, but glyoxal is most effective.

The coating solution is a solution of the above-mentioned starch and dialdehyde in water. The feature of the present invention is that the pH of this solution is 4-8, preferably 5-7, and particularly preferably 6-.
It is limited to 7. When the pH is 4 or less, the viscosity of the coating solution is increased and the coatability is deteriorated. On the other hand, when the pH is 8 or more, the adhesiveness during rewetting and the effect of preventing paper dust are not exhibited.

As the alkali used for adjusting the pH, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium acetate and potassium acetate are practical.

[0014] The mixing ratio of each component in the coating solution, de
0.1-15 % by weight, preferably 0.5-10
% By weight. If it is 0.1% by weight or less, it is difficult to obtain a sufficient paper strength-enhancing effect. The dialdehyde should be 0.5 to 30% by weight based on starch , preferably 1
Is about 20% by weight. Is 0.5 wt% or less can not be obtained effects of preventing and paper dust preventing adhesive, stiff Contact decrease in surface strength of the paper is 30 wt% or more.

There is no particular limitation on the preparation of the above coating solution, and starch and dialdehyde are dissolved in water, and then the pH is adjusted. Alternatively, the pH-adjusted dialdehyde and starch may be dissolved in water.

In the present invention, other additives may be contained or used in combination as desired within a range not hindering the present invention. Other additives include, for example, styrene-butadiene copolymer latex, styrene-butadiene-methacrylic acid ester copolymer latex, and other synthetic rubber-based latex, urea resin, epoxy resin, polyamide resin, melamine resin, etc. , Cross-linking agents such as borax, boric acid, aluminum sulfate, magnesium acetate, and defoaming agents, mold release agents, preservatives, insect repellents, rust preventives, thickeners, glycerin, diethylene glycol, plasticizers such as ethylene glycol, etc. Can be mentioned.

[0017] The method of the present invention, Ru is used to clear coating of paper.

As the base paper to be coated, a high yield pulp used in newspapers, weekly magazines, etc., having a pulp composition of 50 to 100 is used.
It is a paper containing wt% .

When applied to paper, a size press coat, a gate roll coater method, an eardactor method,
Any conventionally known method such as a blade coating method can be adopted. The coating amount can be arbitrarily selected according to the desired properties of the paper, but is usually about 0.1 to 5 g / m ² ( Demp
(As solid content). The drying condition after coating can be arbitrarily selected according to the properties of the paper, but it is usually performed at 80 to 250 ° C. for about 2 to 60 seconds.

[0020]

In the present invention, it is possible to obtain a base paper, particularly newsprint base paper, which does not adhere to or wrap around an offset rotary press and does not generate paper dust.

[0021]

EXAMPLES Next, the present invention will be described more specifically by way of examples. In the examples, "parts" and "%" are based on weight unless otherwise specified. Example 1 2400 parts water with 100 parts starch and 5 glyoxal
Part (in terms of solid content) was dissolved, and the pH of the system was adjusted to 6.5 with sodium hydroxide to obtain a base paper coating solution.

Next, using a test size press manufactured by Kumagai Riki Co., Ltd., a nip pressure of 11 Kg / cm and a speed of 9
Under a condition of 0 m / min, the solution was applied to a newspaper base paper (high yield pulp content 75%, basis weight 40 g / m ² ) so that the amount of starch deposited was 0.4 g / cm ^2. ℃, 1
Super calender treatment (temperature 80
℃, linear pressure 40Kg / cm, speed 10m / min, 2Pa
The coated paper was obtained. The coated paper at 20 ° C, 65% R
After conditioning the humidity for 24 hours with H, the following physical properties were measured. The results are shown in Tables 1 and 2.

[Measurement of Adhesiveness of Coated Paper] (1) Adhesiveness between Coated Papers Two coated papers having a width of 50 mm and a length of 100 mm are heated at a temperature of 20 ° C.
Of water for 5 seconds. Next, these two sheets are superposed and one uncoated paper is placed on each of both outer sides thereof, and super calender treatment (linear pressure 400 kg / cm, speed 5 m / mi
n, 1 Pass) was used as a sample. This sample was peeled by 180 degrees using a tensile tester (TENSILON / UTM-II-20) at a tensile speed of 40 mm / min, and the peel strength was measured (g / 50 mm).

(2) Adhesiveness between coated paper and rubber plate A coated paper having a width of 100 mm and a length of 150 mm was immersed in water at a temperature of 20 ° C. for 5 seconds. Then put this on a rubber plate (150 mm
X150 mm, made by NBR), and uncoated paper was placed thereon and pressed at a pressure of 50 kg / cm ² for 5 seconds to prepare a sample. The peel strength of this sample was measured by the same method as (1) (g / 100 mm). [Measurement of Paper Powder Generation of Coated Paper] The surface of the coated paper for evaluation test was lightly rubbed with a hand to determine whether or not paper powder was generated. ○: No paper dust is generated △: Paper dust is slightly generated ×: Paper dust is generated

[Measurement of surface strength of paper] About coated paper for evaluation test Using a RI printing aptitude tester manufactured by Akira Seisakusho Co., Ltd., FIN IN IN DAINIPPON INK CO., LTD.
Printing was performed using KTV-10, and dry pick (printing in a state where the coated paper was dried) and wet pick (printing in a state where the coated paper was wet) were visually determined based on the following criteria. A: No change B: Slight swelling C: Slight picking swelling D: Many picks E: Paper tearing

Examples 2 to 4 Experiments were conducted according to Example 1 under the conditions shown in Table 1 and Table 2. The results are shown in Tables 1 and 2.

Comparative Examples 1 to 5 The use of glyoxal was omitted (Comparative Example 1), the pH of the coating aqueous solution was set to 2 (Comparative Example 2), and the pH of the coating aqueous solution was set to 9 (Comparative Example 3) . Compounding amount
To 0.1 parts (Comparative Example 4) and 50 parts (Comparative Example 5)
The experiment was performed according to Example 1 except that the above was performed. The results are shown in Tables 1 and 2.

[Table 1] Composition of coating liquid Starch sorption (g / m ² ) Starch GX pH Example 1 100 5 6.5 0.4 Example 2 100 0.5 6.3 0.4 Example 3 100 30 6.5 0.4 Example 4 100 5 6.5 1.0 Comparative Example 1 100 0 6.5 0.4 Comparative Example 2 100 5 2 No uniform coating Comparative Example 3 100 5 9 0.4 Comparison Example 4 100 0.1 6.5 0.4 Comparative Example 5 100 50 6.5 0.4

[Table 2] Adhesive Paper Powder Surface Strength Paper / Paper Paper / Rubber Wet Dry Example 1 0.5 1.5 ○ C C Example 2 1.0 3.5 Δ C C Example 3 0.5 1.4 ○ C C Example 4 3.0 5.0 ○ A A Comparative example 1 4.0 80 × C C Comparative example 2 − − − − − Comparative example 3 2.0 40 × CC Comparative example 4 3.7 73 ○ to Δ C C Example 5 0.8 2.2 ○ C to D C to D ( Note) GX: Glyoxal

Examples 7-8 The same procedure as in Example 1 was carried out using papers with a high yield pulp content of 55% and 95%. The same effect as in Example 1 was obtained.

[0031]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a base paper that does not adhere to or wrap around an offset rotary press and does not generate paper dust, especially a newsprint base paper.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) D21H 19/10 D21H 19/24

Claims (3)

(57) [Claims] 1. A composition comprising starch and a dialdehyde on a base paper in which 50 to 100% by weight of the pulp composition is a high-yield pulp, and the dialdehyde is added in an amount of 0.5 to 0.5 with respect to the starch.
A method for coating paper, which comprises 30% by weight of a starch solution and a clear coating of a starch- based aqueous solution having a pH of 4 to 8. 2. The method according to claim 1, characterized in that a base paper for newsprint is used as the base paper. 3. The method according to claim 1, wherein glyoxal is used as the dialdehyde.