JPS62257498A - Production of paper excellent in interlayer strength - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a method for producing laminated paper having excellent glabellar strength.

(Prior art and its problems) Conventionally, in the production of laminated paper, in order to prevent peeling during lamination, in order to improve the interlayer adhesion strength,
A method is adopted in which an ungelatinized starch dispersion is sprayed onto the surface of the wet paper just before the paper is combined, the paper is combined in a conventional manner, and then the starch is gelatinized by heating in a part of the dryer of the paper machine. ing.

However, in this manufacturing method, most of the applied starch penetrates into the inside of the paper layer, and only a portion of the starch acts effectively on the papermaking surface, which is uneconomical. In addition, in order to improve glabella strength, it is necessary to gelatinize the ungelatinized starch that remains on the papermaking surface, but gelatinization is often insufficient just by heating in the dryer section of the paper machine. However, there is also the drawback that it is difficult to obtain stable glabellar strength.

Furthermore, since the non-gelatinized starch dispersion is applied by spraying, the spray nozzle is likely to become clogged, which poses a problem in terms of stable operation.

(Problems to be solved by the invention) In order to solve the above-mentioned difficulties in producing conventional laminated paper, the present invention has developed a fine colloidal dispersion that does not clog the spray nozzle, instead of the conventional ungelatinized starch dispersion. We have created an excellent adhesive solution that retains its active ingredients without wasting any waste when applied to the wet paper surface immediately before paper-making, and that exhibits sufficient adhesion strength to achieve interlayer adhesion without heating. It is an object of the present invention to provide a method for producing laminated paper with excellent glabellar strength.

(Means for Solving the Problems) In view of the fact that the starch-based interlayer adhesive used in the past has a disadvantage in that it uses an ungelatinized starch dispersion, the present invention is directed to the use of an ungelatinized starch dispersion. Alternatively, if a cationically modified starch, which can effectively utilize the attraction force with the surface charge of the wet paper, is used as the main agent for the interlayer adhesive, and an anionic polymer is used in combination to produce a fine colloid that has cationic properties as a whole, the spray nozzle will become clogged. Because it does not cause any damage and is in the form of a cationic fine colloid,
It was developed based on the discovery that it was able to adhere sufficiently to the surface of wet paper, and that it was already in a state where adhesive strength could be exerted even after it was applied. ``A method for producing paper combs by spraying a fine colloidal liquid containing cationic modified starch and anionic polymer as an interlayer adhesive onto the paper surface.''
It is in.

The cationically modified starch used in the present invention preferably contains 1 mol% to 15 mol% of cationic groups based on glucose units, and has a viscosity (at 25°C) of 50 cps or less at a solid content of 2% by weight. This is because if the cationic group is less than 1 mol % based on the glucose unit, it is difficult to form a fine colloid with the anionic polymer and it is difficult to remain even when sprayed on the wet paper surface. This is because, even with the above, modification costs are incurred, and no improvement in the above-mentioned effects can be expected, so there is no economic value.

In addition, its viscosity (25°C) is 50 cp at a solid content of 2% by weight.
The reason why it is necessary to use one having a speed of less than 10 cps, particularly in the range of 10 to 30 cps, is because it is necessary to improve the workability of spray coating and to prevent clogging of the spray nozzle.

As specific examples of cationically modified starches having such physical properties, those commonly used as paper strength enhancers can be used.

On the other hand, the anionic polymer used in the present invention is a vinyl-bonded polymer containing 10 mol% to 100 mol% of anionic groups, and its viscosity (25°C, pH 1 to 4)
It is preferable to use one having a solid content of 5% by weight and 100 to 100.0 OOcps.

This is because if the anionic group content of the anionic polymer is less than 10 mol %, it will not be possible to form a fine colloid with the cationically modified starch, and no residual effect on the wet paper surface can be expected by spray coating.

In addition, its viscosity (25°C, p) II to 4) is 100 to 100.000 cps, especially 1000 to 100.000 cps at a solid content of 5% by weight.
The reason why it needs to be 30,000 cp3 is because it is necessary to improve the workability of spray coating and to prevent clogging of the spray nozzle.

As specific examples of anionic polymers having such physical properties, those commonly used as paper strength enhancers can be used.

The blending ratio of the above-mentioned cation-modified starch and anionic polymer is 99.510.5 to 70/3 in terms of solid content weight ratio.
0, particularly preferably in the range of 99/1 to 90/10, because if it is 99.510.5 or more, the generation of fine colloids cannot be expected by the combination of the two, while 70/3
This is because if it is less than 0, the cationic nature of the fine colloids decreases, making it impossible to stop on the wet paper surface, and the expected effect cannot be obtained.

(Operations and Effects of the Invention) According to the present invention having the above configuration, instead of the conventional ungelatinized starch dispersion, a cationically modified starch that can effectively utilize the attraction force with the surface charge of the wet paper is used as the main ingredient of the interlayer adhesive. Moreover, since we have created a fine colloid that has cationic properties as a whole by using an anionic polymer, not only is stable operation possible without clogging the spray nozzle, but also a fine colloid with cationic properties. Therefore, even if it is applied to the wet paper surface just before the paper is combined,
It is economical because it penetrates into the inside of the paper and the active ingredients do not escape and most of them remain on the wet paper surface, and it is already in a state where it can exhibit adhesive strength even after being applied. It is extremely economical and efficient for producing laminated paper.

Hereinafter, the present invention will be specifically explained based on Examples.

(Example) (Preparation example 1 of cationic modified starch liquid) 250 g of water and 250 g of corn starch were charged into an 11-capacity separable flask equipped with a stirrer, a thermometer, and a regular condenser, and the mixture was stirred. -2~Hydroxy-propyltrimethylammonium chloride 50χ aqueous solution 20g, 4
Add 8g of 8x sodium hydroxide and raise the temperature to 50°C. After the reaction is completed at 50 to 60° C. for 5 hours, the mixture is neutralized with 10× hydrochloric acid, methanol is added thereto, filtered, and the filtration residue is washed with water-containing methanol to obtain a cation-modified starch powder. When the Ni content of this powder was determined by the Kelpool method and the cation modification rate was calculated, it was found that 3.3 moles χ of glucose units were cationized.

This cation-modified starch powder is hereinafter referred to as C3(A). Next, add 950 g of water to an 11-volume separable flask.

Prepare C5(A) sog, raise the temperature to 90℃, and AP
Add 0.1 g of S (ammonium persulfate). 30
Stir and hold at 90-95° C. for minutes. The resulting cationic modified starch liquid C3(^) -+11 has a solid content of 4.6
The viscosity at 25° C. was 110 Cp3.

(Preparation example 2 of cationic modified starch liquid) A cationic modified starch liquid CS (A )-(2) were adjusted.

(Preparation example 3 of cationic modified starch liquid) 50 g of water and 50 g of potato starch were charged into an 11-volume separable flask equipped with a stirrer, a thermometer, and a regular condenser, and stirred. Next, 3-chloro-2- Hydroxy-propyltrimethylammonium chloride 50x aqueous solution 10g, 48
Add 4 g of χ sodium hydroxide and raise the temperature to 50°C. After the reaction is completed, it is neutralized with 10x hydrochloric acid, 850g of water is added, and 98%
When the temperature is raised to ℃ and gelatinized, the resulting cationically modified starch liquid C5 (B) has 7.8 moles of glucose units χ cationized, solid content 4.9χ, and a viscosity at 25℃ of 13
It was 0 cps.

(Preparation example 1 of anionic polymer) 94 parts by weight of 80x acrylic acid monomer and 404 parts by weight of water are charged into a lj-capacity glass four-hole flask equipped with a stirrer, a thermometer, and a regular condenser, and heated with a mantle heater. . At 42° C., 0.2 parts by weight of sodium sulfite and 0.25 parts by weight of sodium persulfate are added. After confirming the generation of heat 2 to 3 minutes after the addition, stirring is continued until the maximum temperature is reached, and the reaction is continued for 30 minutes while maintaining the maximum temperature. Thereafter, a predetermined amount of water is added and cooled to obtain a polyacrylic acid aqueous solution. The solid content of this polyacrylic acid aqueous solution is 15 times i! χ and the viscosity is 2500c at 25℃
ps, PII was 2.2. This is PP^-+1
Set to 1.

(mHM 2 of anionic polymer) Solid content 15% by weight in the same manner as in Preparation Example 1 except that 0.5 parts by weight of sodium sulfite and 0.5 parts by weight of sodium persulfate were added.
, a polyacrylic acid aqueous solution PPA-+21 having a viscosity of 5700 cps at 25°C and a pH of 2.2 was obtained.

(Example 3 of preparation of anionic polymer) Into an 11-volume glass four-hole flask equipped with a stirrer, a thermometer, and a regular condenser, 50 parts by weight of 40x acrylamide,
10 parts by weight of 80x acrylic acid and 250 parts by weight of water are charged, and after raising the temperature to 50°C, 0.05 parts by weight of sodium persulfate is dissolved in 5 parts by weight of water and added.

Add. After being allowed to react for 3 hours, a predetermined amount of water was added and stirred to achieve a uniform solid content of 5.0% by weight.
An aqueous polyacrylic acid solution having a viscosity (25°C) of 2B, 0OOcps, and a pH of 2.4 is obtained. This polyacrylic acid aqueous solution is referred to as PPA-(31).

(Manufacturing example 1) Five Emperors Week! The cationically modified starch C3(A)-fl) 9Bg
After dissolving in 300 g of water, the anionic polymer P
Add 113.3g of PA-+ and dilute the total amount with water to 7.50g.
It was set to 0g. As a result, a fine colloidal liquid having a solid content lχ and a cation-modified starch/anionic polymer ratio of 90/10 is prepared.

Add 0.3 sizing agent (il! Shinkasei, bar size L-50) to the 2χ valve slurry (LBKP 450w1esf).
χ (in terms of pulp solid content), followed by addition of sulfuric acid band 2.0χ (in terms of pulp AlO3χ containing liquid), and the weighing amount was 100 g/
A wet paper d was obtained. The above liquid coating solution Tl) is applied to the surface of this wet paper.
Spray 60g/rd. After that, T
APPI handmade sheet, machine-made scale 11oo,
/rrt wet paper was layered, press dehydrated under certain conditions, and then dried for 3 minutes in a 105° C. rotary drum dryer to obtain a paper sheet (1).

(Production Example 2) After dissolving 76 g of the C3(A)-t2+ in 300 g of water, the anionic polymer PPA-+21 Log
was added, and the total amount was made up to 500 g with water. This results in
A fine colloidal liquid having a solid content lχ and a cation-modified starch/anionic polymer ratio of 70/30 was obtained. This is referred to as coating liquid (2).

A laminated sheet (2) was obtained in the same manner as the preparation of the laminated paper in Production Example 1, except that 60 g/rd of the coating liquid (2) was sprayed onto the surface of the laminated moisture control paper.

(Manufacturing example 3) l 奄豱! week! After dissolving 92 g of the C3 (B) in 300 g of water, adding 3110 g of the anionic polymer PPA-+,
The total amount was made up to 500 g with water. As a result, the solid content IL
Cation modified starch/anionic polymer ratio is 90/
10 fine colloid liquid (3) was obtained, and this was applied to the coating liquid (3).
shall be.

Her sister-in-law, Wataruto Retired Emperor! A laminated paper (3) was obtained in the same manner as the preparation of laminated paper in Production Example 1, except that 60 g/rd of the coating liquid (3) was sprayed onto the surface of the wet paper.

(Comparative Example 1) Easy to apply! Cornstarch 2B was adjusted to a total amount of 500g with water to obtain a cornstarch coating liquid (4) with a solid content of 5χ.

A laminated paper (4) was obtained in the same manner as the preparation of laminated paper in Production Example 2, except that 60 g/cd of the coating liquid (4) was spray-coated on the surface of the moisture control paper.

(Comparative Example 2) 60g/n of water on the surface of the humidity control paper? A laminated paper (5) was obtained in the same manner as in Preparation Example 2 except for spray coating.

(Test example) The papermaking process prepared in the above manufacturing examples and comparative examples (1
The glabellar strength of samples 1 to (5) was measured as follows, and the test results were compared.

The interlaminar strength was measured using a tensile tester by pasting the paper sheets (11 to (5)) with double-sided adhesive tape to a rectangular metal block with a flat surface of 1 inch x 1 inch. This measurement was conducted in accordance with TAPPI T5065u68. I will do it.

Test results (Table 1) Sewing glabellar strength (Kgf) Production example 1
(Shojiawasegi (11) 22.22
(2121,0 3(3124,7 Comparative example 1 (4118,12+51
12.7 As is clear from the above results, according to the present invention, laminated paper with excellent interlayer strength can be obtained.

Claims (4)

[Claims] (1) After spraying an interlayer adhesive onto the surface of the wet paper just before the paper is combined, a liquid containing cationic modified starch and anionic polymer is applied as an interlayer adhesive to the surface of the wet paper just before the paper is combined. A method for producing laminated paper with excellent interlayer strength, characterized by spray coating on the wet paper surface. (2) Cationically modified starch is 1 per glucose unit
The manufacturing method according to item (1) above, which contains cationic groups in an amount of mol % to 15 mol %, and has a viscosity (at 25° C.) of 50 cps or less at a solid content of 2% by weight. (3) Anionic polymer is 10 mol% to 100 mol%
A vinyl-bonded polymer containing anionic groups whose viscosity (25°C, pH 1-4) is 5% by weight of solids.
100 to 100,000 cps. (4) The manufacturing method according to item (1) above, wherein the blending weight ratio of the cation-modified starch and the anionic polymer is 99.5/0.5 to 70/30.