JP2572233B2 - Composition for paper surface coating - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a paper surface coating composition exhibiting an excellent effect of improving printability and water resistance of paper.

[Conventional technology]

The development of printing technology in recent years has been remarkable, and with the increase in printing speed and quality, high printing suitability has been required for printing paper.

Conventionally, surface coating agents for increasing the surface strength of paper and improving printability include starch derivatives such as starch, oxidized starch and cationized starch, and cellulose derivatives such as carboxymethyl cellulose (hereinafter abbreviated as CMC). , Polyvinyl alcohol (hereinafter abbreviated as PVA)
A natural or synthetic water-soluble polymer compound such as polyacrylamide (hereinafter abbreviated as PAAm) or anion-modified polyacrylamide is used, and among them, oxidized starch is most frequently used.

[Problems to be solved by the invention]

However, in response to recent demands for high printability and improvement in water resistance, the above-mentioned existing surface coating agents have not been able to obtain satisfactory results, resulting in insufficient paper surface strength or insufficient water resistance. Are causing more printing troubles. In particular, there is currently no effective paper for neutral paper whose production has been increasing recently, and the appearance of a high-performance surface coating agent has been desired.

[Means for solving the problem]

The present inventors have conducted intensive studies to respond to the request, and found that when a starch derivative such as starch, oxidized starch and cationized starch, and a water-soluble polymer compound such as CMC, PVA or PAAm are used in combination with chitosan, the water-soluble It has been found that printability and water resistance are remarkably improved as compared with the case where a polymer compound is used alone, and it is found that the present invention exerts an excellent effect not only on acidic paper but also on neutral paper, thereby completing the present invention. .

 Next, the present invention will be described in detail.

The chitosan used in the present invention is represented by the general formula (I) (1 → 4) -2-acetamido-2-deoxy-β-.
It is a deacetylated product of chitin having the structure of D-glucan.

Chitin forms a supporting tissue for crustaceans, insects, and fungi, and is industrially obtained from crusts such as crabs and shrimps by decalcification and deproteinization. The chitosan used in the present invention is obtained by deacetylation of chitin, and the deacetylation method is not particularly limited, and any known method can be used. From the viewpoint of obtaining an aqueous solution of chitosan, the degree of deacetylation is preferably 50% or more. If necessary, the viscosity is adjusted to a predetermined value by a known method using sodium hypochlorite, sodium nitrite, hydrogen peroxide or the like. The viscosity of a 1% aqueous solution of chitosan dissolved in acetic acid is preferably 3 to 300 centipoise under the conditions of a Brookfield M-type viscometer at 25 ° C. and 60 rotations, and particularly preferably 3 to 50 centipoise. Most preferred.

The method of using chitosan used in the present invention is not particularly limited, but it is most convenient to use an aqueous solution of chitosan. Specifically, using chitosan as an inorganic or organic acid,
Adjust to pH 6.5 or lower to make an aqueous solution.

Although chitosan alone exhibits excellent performance as a surface coating agent, it is expensive compared to inexpensive existing surface coating agents such as starch and oxidized starch, and economic disadvantages are inevitable. Therefore, the paper surface coating composition of the present invention comprising chitosan and an inexpensive water-soluble polymer compound is very economically advantageous as compared with the case where chitosan is used alone, and also has good printability and water resistance. The water-soluble polymer compound can be improved to a necessary and sufficient extent to a higher degree than when the water-soluble polymer compound is used alone. And the size effect is improved, and it is effective not only for acidic paper but also for neutral paper.

Examples of the water-soluble polymer compound used in combination with chitosan in the present invention include starch, oxidized starch, starch derivatives such as cationized starch, cellulose derivatives such as CMC, PVA
And PAAm are preferred, and starch derivatives such as oxidized starch and cationized starch are most preferred.

The surface coating composition of the present invention can be prepared by mixing with an aqueous solution of the water-soluble polymer compound in which an aqueous solution of chitosan has been previously dissolved, or by mixing with a dispersion of the water-soluble polymer, followed by cooking. it can.

Chitosan and the water-soluble polymer compound can be mixed in any ratio, and the mixing ratio can be determined as necessary.

In order to apply the paper surface coating composition of the present invention to the paper, it is preferable to use a size press, a gate roll coater, a blade coater or a calender. Coating can also be carried out with a bar coater, knife coater, air knife coater or the like.

[Examples] Hereinafter, the present invention will be described specifically with reference to Examples.

Example 1 Chitosan aqueous solution with reduced molecular weight (addition of acetic acid of the same weight)
And an aqueous solution of oxidized starch (manufactured by Oji Constarch Co., Ltd., trade name: Oji Ace A), which was previously cooked, was mixed at the mixing ratio shown in Table 1 below to prepare. The obtained coating liquid having a solid content of 5% is applied and dried on acidic woodfree paper of the following (1) as in the following (2), and the surface strength, paper strength,
The size effect was measured under the following condition (3).

(1) the surface of the base paper treated with non acidic conditions in the paper making the high quality paper pulp: bleached kraft pulp softwood / hardwood = 3/7 basis weight: 65 g / m ^2, the paper filler: Talc 14% (inner添薬product) sulfate Band: 1.5%, rosin size: 0.1%, base paper stiffness degree: 1.5 seconds (2) Coating and drying Double-side coating (nip pressure 20 kg / cm) using a test size press (Kumagaya Riki Kogyo Co., Ltd.) , A coating speed of 100 m / min, and a coating temperature of 60 ° C.), followed by drying with a drum dryer at 80 ° C. for 50 seconds. After drying, it was left for 24 hours in a constant temperature and humidity room of 20 ° C. and 65% RH and then subjected to a test.

(3) Measurement conditions Sizing degree: Stequicht method; JIS P-8122-1976 Cobb method (2 minutes); JIS P-8140-1976 Pen writing size degree; J. TAPPI paper pulp test method No. 12 Dry tensile strength: shopper Type tensile tester; JIS P-8113-1976 Wet tensile strength: Shopper type tensile tester; JIS P-8135-1976 Water immersion time 30 minutes Surface strength: Dry pick RI printing tester, nip width 10mm ink; FINE INK. (Dai Nippon Ink and Chemicals, for IGT printing suitability test) TV 16 Wet Topic RI printing tester, nip width 10 mm, using Molton roll, ink; CAPS G (Dai Nippon Ink and Chemicals, for offset) TV 8 The paper peeling state after printing was visually observed, and a five-grade evaluation was performed with 5 being excellent and 1 being poor. As a result,
That is, Table 1 shows the sizing degree and paper strength of the obtained coated paper.

Example 2 A low-molecular-weight aqueous solution of chitosan (addition of the same weight of acetic acid) and an aqueous solution of pre-cooked oxidized starch (manufactured by Oji Constarch Co., Ltd., trade name: Oji Ace A) were mixed at the mixing ratio shown in Table 2 below. Prepared. The obtained coating solution having a solid content of 5% was applied to neutral paper under the conditions described in (1) to (3) below, and the surface strength and size effect of the coated paper were measured. Table 2 shows the obtained results.

(1) base paper surface treatment have not calcium carbonate-containing paper pulp: bleached kraft pulp softwood / the hardwood = 3/7 basis weight: 65 g / m ^2, the paper filler: heavy calcium carbonate 14% (inner添薬product) alkyl Ketene dimer: 0.06%, polyacrylamide-based retention aid: 0.03%, Stekigt sizing degree of base paper: 0.4 seconds, (2) Coating and drying Coating and drying were performed in the same manner and under the same conditions as in Example 1. .

(3) Measurement conditions Measurement was performed in the same manner as in Example 1.

Examples 3 to 6 A low molecular weight chitosan aqueous solution (1
% Viscosity of 12 cps) and pre-cooked cationized starch (commercial product for size press) (Example 3), PVA (commercial product with complete saponification, polymerization degree 500) (Example 4), CMC (viscosity of 1% solution) 80 cps commercial product at 25 ° C) (Example 5) or PAA
m (anion-modified commercial product for size press) (Example 6) was mixed with a coating solution having a solid concentration of 4% and mixed with a high-quality paper (acid) under the following conditions (1) to (3). Paper) and its surface strength and size effect were measured. However, the solid content concentration of the coating liquid composed of chitosan and CMC was 2%. Table 3 shows the obtained results.

(1) Base Paper Fine paper made under the same acidic condition as in Example 1 but without surface treatment was used.

(2) Coating and drying Examples 3, 4 and 6 are No. 3 bar coaters, and Example 5 is N
The coating was performed on one side with a bar coater of o.6, and dried with a drum dryer at 80 ° C. for 50 seconds. 20 ° C, 65% RH after drying
For 24 hours in a constant temperature and humidity chamber.

(3) Measurement conditions Measurement was performed in the same manner as in Example 1.

Example 7 A low molecular weight chitosan aqueous solution (1
% Viscosity of 20 cps) and a pre-cooked aqueous solution of oxidized starch (Oji Ace A manufactured by Oji Cornstarch Co., Ltd.), and a coating solution having a solid content of 5% was prepared by the following (1) to
Under the condition of (3), high-quality paper (acid paper) was coated, and its surface strength and size effect were measured. Table 4 shows the obtained results.

(1) Base paper Fine paper made under acidic condition without surface treatment Pulp: bleached kraft pulp softwood / hardwood = 50/50 basis weight: 60 g / m ² , filler in paper: talc: 13%, (internal chemicals) Rosin size: 0.1%, Sulfuric acid band: 1.5%, Stekigt size of base paper: 2.5 seconds, (2) Coating and drying One side coating with a No. 4 bar coater, 80 ° C, 50 seconds with a drum dryer Dry under conditions. 20 ℃ after drying, 65%
The specimen was left in a RH constant temperature and humidity chamber for 24 hours for the test.

(3) Measurement conditions Measurement was performed in the same manner as in Example 1.

Comparative Examples 1 to 8 As shown in Tables 1 to 4, the coatings of Comparative Examples 1 to 8 were carried out in the same manner as the corresponding Examples, except that chitosan and the water-soluble polymer compound were not used. A liquid was prepared, and coated, dried and measured under the same conditions as in the corresponding examples. The results are shown in Table 1 (Comparative Example 1), Table 2 (Comparative Example 2), Table 3 (Comparative Examples 3 to 6), and Table 4 (Comparative Examples 7 to 6).
8).

From the above results, those of Examples 1 to 7 have significantly improved surface strength as compared with those of Comparative Examples 1 to 8,
The size effect is also improved, and the effect of the present invention is clear.

〔The invention's effect〕

As described above, by using the paper surface coating composition of the present invention, the printability of the paper is improved, high-speed printing can be performed without any trouble, and the printed result can be beautifully finished. Further, since the surface coating composition of the present invention improves the water resistance of paper, it can be said that the composition is particularly suitable for offset printing using dampening water.

Continuing on the front page (72) Inventor Satoshi Takizawa 17-2 Yawata Kaigandori, Ichihara-shi, Chiba Prefecture Inside Dick Hercules Co., Ltd. (72) Inventor Hisashi Hisashi 481 Sakurai 481 Kisarazu-shi, Chiba Prefecture 1284-23 Kamijiya, Okegawa City, Prefecture (56) References JP-A-63-135594 (JP, A) JP-A-63-203896 (JP, A)

Claims (5)

(57) [Claims] 1. An aqueous solution of chitosan and (2) one or more selected from the group consisting of starch and starch derivatives, cellulose derivatives, polyvinyl alcohol and polyacrylamide, and a pigment. A composition for coating the surface of paper, characterized in that there is no coating. 2. The viscosity of an aqueous solution of chitosan dissolved in acetic acid is as follows:
3 to 300 centipoise at 1% by weight (2
The composition for coating the surface of paper according to claim 1, wherein the composition is measured at 5 ° C and 60 rpm. 3. The paper surface coating composition according to claim 1, wherein the starch derivative is oxidized starch. 4. The paper surface coating composition according to claim 1, wherein the starch derivative is a cationized starch. 5. The paper surface coating composition according to claim 1, wherein the cellulose derivative is carboxymethylcellulose.