JPH03167388A - Converted paper - Google Patents

Abstract

PURPOSE:To provide the title paper having Japanese paper feeling in terms of porosity, flexibility, etc., and capable of high-speed printing using one of various kinds of printing machine, comprising, as the essential components, specific papermaking fiber and a small amount of fibrous water-insoluble carboxymethylcellulose with its surface to be printed imparted with a chitosan- contg. material. CONSTITUTION:A mixture comprising (A) >=20wt.% of at least one kind of papermaking fiber selected from bast fiber from wood-based bast of e.g. mulberry and leaf fiber from e.g. Manila hemp, (B) wood pulp, and (C) 2-20wt.% of fibrous water-insoluble carboxymethylcellulose or its salt (pref. a sodium salt of carboxymethylcellulose 0.5-1.2 in substitution degree) is put to a papermaking machine followed by drying or semi-drying, and the resulting product is immersed in a solution of chitosan prepared by dissolving chitosan in an inorganic or organic acid (pref. acetic acid) to impart the surface of the product with 0.1-4.0wt.%, based on the paper weight, of chitosan, thus obtaining the objective converted paper.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to processed paper having a Japanese paper-like texture and appearance that can be printed at high speed with various high-performance printing machines.

[Problems to be solved by conventional techniques and inventions] Conventionally,
Bulky paper made from papermaking fibers as the main raw material is porous, light, flexible, and tough, and is highly valued for its so-called Japanese paper-like texture and appearance. however,
Its printability is inferior to that of printing paper made precisely from wood pulp, or processed paper such as coated paper, which is coated on western paper. In particular, when printing with a rotary printing press or a rotary printing press, paper fibers called paper dust drop off and fluffing called paper peeling occurs, making it unsuitable for high-speed printing.

The following methods have been adopted as conventional methods for preventing paper dust and paper peeling.

■A method of selecting raw material fibers and beatability to create a tight and tight paper quality. This method is used for securities paper, etc., but there is a problem in that the so-called Japanese paper-like texture and appearance, such as porosity, lightness, and flexibility, are lost.

■A method of processing using a hot pressure roll such as super calender processing. This method also has the same problems as the above (2).

■A method of mixing or impregnating a filler such as inorganic powder with a binder such as synthetic latex. This method has the problem that, in particular, porosity is lost and the appearance changes to that of Japanese paper.

■Method of attaching natural polymers such as starch and chitosan. This method has the problem that if the amount of adhesion is large, the same problem as described in (2) above occurs, and if the amount of adhesion is too small, the effect is small.

Note that there is a composition for coating the surface of paper that contains an aqueous chitosan solution and a cellulose derivative such as carboxymethyl cellulose (Japanese Patent Application Laid-open No. 14396/1983); There is a problem in that coagulation occurs due to the ionic action of anions. Further, this carboxymethyl cellulose forms an aqueous solution and does not form fibers.

The purpose of the present invention is to use papermaking fibers as the main raw material to create porous,
We provide processed paper that maintains the texture and appearance of washi paper, such as lightness and flexibility, and has fibers that are tightly bonded to prevent paper dust and paper peeling from occurring when printing with a rotary printing machine or rotary printing machine. It's about doing.

[Means to solve the problem]

In order to solve the above problems, the present invention uses one or more types of papermaking fibers selected from bast fibers and leaf fibers, and a small amount of fibrous water-insoluble carboxymethyl cellulose or its salt as essential components. This paper employs a method in which chitosan-containing material is attached to at least the printing surface.

Next, each of the above components will be explained in detail.

The bast fibers are preferably pulp-like fibers obtained from woody basts such as Sanpoku, Kaku, Gampi, and Mulberry.

This bast fiber has a unique texture and appearance even among Japanese paper-like materials.
It can impart a high degree of toughness to paper as well as fiber luster.

As the leaf fiber, pulp fibers obtained from Manila hemp, sisal hemp, banana, pineapple, etc. are preferred. These leaf fibers provide paper with porosity, lightness, flexibility and moderate toughness.

The higher the weight ratio of the bast fibers and leaf fibers in the paper, the more the above-mentioned features will be imparted to the paper quality, but the price will also usually be higher. If this weight ratio is 20% by weight or more, texture, appearance, and other paper qualities will be imparted depending on the ratio. When this ratio is low, wood pulp or cellulose-based chemical fibers are usually mixed as other papermaking fibers.

Next, as the fibrous water-insoluble carboxymethyl cellulose or its salt, one having a degree of substitution of less than 0.5 is preferable, and one that does not lose its fibrous form even if it is re-dried after being dispersed in water is preferable. Cellulose raw materials include softwood, hardwood, Manila hemp, etc., but those made from thin cellulose fibers are preferred. The content of this fibrous water-insoluble carboxymethylcellulose or its salt is not preferably too high, and is preferably in the range of 2 to 20% by weight. If it exceeds 20% by weight, the texture and appearance will change, and it will start to look different from Japanese paper. If it is less than 2% by weight, the effect will be small. A range of 3 to 10% by weight is particularly preferred.

Next, chitosan is extracted from acid from the outer shells of crustaceans such as crabs and shrimp.
It is obtained by deacetylating chitin obtained by alkali treatment or the like. It is preferable that the color is white and does not contain any insoluble matter. Although the effect varies depending on the viscosity and degree of deacetylation, most of the effects can be corrected by adjusting the amount of adhesion. Chitosan is dissolved in an aqueous solution of an inorganic or organic acid and applied to the paper.

As the solvent, an aqueous solution or liquid of an organic acid such as formic acid, acetic acid, or glycolic acid is preferable. Moreover, a commercially available product dissolved in an acetic acid aqueous solution can also be used.

The chitosan-containing material is applied by impregnation or coating with an acidic aqueous solution of chitosan. If the paper is porous, the chitosan solution will diffuse into the paper layer even if applied from one side. Therefore,
A uniform application on at least one side will usually accomplish the purpose. As the coating or impregnating method and apparatus, known methods for paper can be used depending on the structure and quality of the paper. For paper that has finished drying, methods such as the dipping method, spray method, kiss roll method, curtain coating method, etc. are adopted, and when coating before the drying is completed, the spray method, size press, and other in-line coaters are used. be able to. The concentration of chitosan in the solution is appropriately selected depending on the target deposition amount and application method, but is usually 5% by weight or less.

The adhesion amount of the chitosan-containing material is 0.0% of the weight of the paper. The range is preferably 1 to 4.0% by weight, and more preferably 0.4 to 2.0% by weight in terms of both the effect of preventing paper dust and paper peeling and the maintenance of tactile sensation including porosity and flexibility.

Next, water-soluble anionic polymers include derivatives of natural polymers and derivatives of synthetic polymers.

For the former, carboxymethyl derivatives of polysaccharides such as carboxymethyl cellulose and carboxymethyl starch and their alkali salts are suitable. Synthetic polymer derivatives include water-soluble substances such as vinyl and polyacrylic polymers modified with carboxyl groups, sulfate ester groups, sulfonic acid groups, phosphoric acid groups, etc. Specifically, carboxyl-modified polyacrylamide Alkaline salts such as polyvinyl alcohol sulfate and polyvinyl alcohol sulfate can be used. The most preferred one is a degree of substitution of 0. 5 to 1.2 sodium salt of carboxymethyl cellulose, the concentration of which is 0. 5-2.
It is preferable that a stable 0% aqueous solution can be easily prepared.

This water-soluble anionic polymer is preferably added while stirring an aqueous solution diluted to have as low a viscosity as possible so as to mix uniformly. Further, for example, it is effective to set the addition location while the slurry is flowing from the mixing tank to the paper screen and add it using a metering pump. The amount added is 0.0% in terms of solid content ratio to the slurry containing the chitosan acidic aqueous solution.
1 to 5.0 is preferable, and 0.2 to 2.0 is more preferable. This ratio is 0. When it is less than 1, the effect of improving surface strength is small, and even when it exceeds 5.0, the effect is not improved any further.

Next, a method for manufacturing processed paper will be explained.

First, papermaking fibers are beaten according to the required paper quality to form a water-dispersed slurry. Next, a small amount of fibrous water-insoluble carboxymethyl cellulose or its salt and additive chemicals as needed are mixed in the mixing tank, and paper is made using a paper machine.
dry. After drying or in a semi-dry state, a chitosan solution is added and then dried.

Bast fibers have a long fiber length and are easily tangled and bound during beating, and high strength can be obtained even with low beating, so it is best to use them without beating.

Leaf fibers may be lightly beaten or simply dispersed, or processed depending on the required paper quality. When wood pulp is used, it is optionally beaten if necessary. In the case of paper where porosity is important, softwood pulp may be used after being lightly beaten.

The fibrous water-insoluble carboxymethylcellulose or its salt is thoroughly stirred and dispersed in water. When using a wet strength agent, it is preferable to use a small amount of a wet strength agent whose cationic property is as weak as possible, since many of them tend to aggregate with the above-mentioned carboxymethyl cellulose. As the wet strength agent, a strong cationic agent such as polyamide amine/ebichlorohydrin type is suitably added in an amount within 1% of the total cellulose fibers. In addition, when applying a chitosan acidic solution to paper using a spray coater on a conveyor net, or when applying a small amount of a highly concentrated solution to one side and drying it with a conveyor dryer or cylinder dryer, use a high-wetting agent. agent is not necessarily required.

As the sizing agent, a known sizing agent such as a rosin-based sizing agent or a neutral sizing agent may be used depending on the conditions of the ink and the printing machine. others,
Known papermaking additives such as antifoaming agents and dryer release agents can be used.

The paper machine is preferably a cylinder type or a short screen type. The fourdrinier method normally used for Western paper is not suitable when bast fibers are mixed or when leaf fibers are mixed in large quantities. For drying, dryers for paper manufacturing and paper processing such as cylinder dryers and hot air dryers can be used within the normal drying temperature range.

[Examples 1 to 3 and Comparative Examples 1 to 3] Examples embodying the present invention will be described below in comparison with comparative examples.

First, Manila hemp pulp that had been pressure-cooked with sodium hydroxide and bleached with sodium hypochlorite was blended with 0 and 10% by weight of water-insoluble fibrous carboxymethyl cellulose with a degree of substitution of 0.33 produced from hardwood pulp. , a handmade sheet with a weight of 40g/m" is made using TAPPI T205
Prepared according to US-71.

The sheet was dried by attaching it to a chrome-plated drum dryer with a surface temperature of 120°.

On the other hand, purified chitosan was mixed and dissolved in equal amounts of glycolic acid and ion-exchanged water to give a weight concentration of 2%. This was diluted appropriately, sprayed onto a handmade sheet, and dried on a chrome-plated drum dryer with a surface temperature of 120°C until the amount of chitosan deposited was 0. 5, 1. Processed paper containing 2.0% by weight of O was prepared.

Regarding this processed paper, density, tear length, wet tear length, Klemm method water absorption (JIS P8141), ink size,
The wax method surface strength was measured and the results are shown in Tables 1 and 2.

The density was measured by the test method specified in JIS P8118. In the case of washi-like paper, which is mainly composed of organic fibrous raw materials and has a trace amount of components other than fibers, as in the present invention, the porosity can be determined by this density value, which is 0.5 g/
ml or less is preferable. This density gives a paper with good printability.

The tear length and wet tear length were determined according to JIS P8113.

Clem's water absorption was measured according to JIS P8141.

The ink size was expressed as the time (seconds) required for the paper to float on the surface of the water-based ink and for the ink to penetrate into the opposite surface and occupy 2/3 of the area of the opposite surface. The dryer contact surface and non-contact surface of the paper were each floated on the ink liquid surface and measured, and the average value was used.

The wax method surface strength was measured by the test method specified in JIS P8129. At least 12A, preferably 13A or more is suitable for high performance printing presses.

In addition, CMC represents carboxymethyl cellulose.

Table 1 l Table 2 As can be seen from Table 1 and Table 2 above, fibrous CMC
In the case of not containing both CMC and chitosan (Comparative Example 1), the case of not containing fibrous CMC (Comparative Example 2), and the case of not containing chitosan (Comparative Example 3), the dry and wet tear length, wax method surface strength, etc. Fibrous CMC has poor performance, whereas fibrous CMC
When chitosan is used in combination (Examples 1 to 3), the dry and wet tear length is improved, and the wax method surface strength is also significantly improved. In particular, compared to Comparative Example 2, which is a processed paper processed by the known chitosan impregnation method, the surface strength is greater at the same adhesion amount and the same density, and therefore the water absorbency is at the same level, yet the ink bleed prevention effect is achieved. Therefore, even in multi-color printing such as gravure printing, relatively clear printing is possible despite the porosity, without paper peeling.

[Example 4] The same manila hemp pulp and bleached softwood pulp as in Example 1 were used, and the latter was beaten to a beating degree of 18°SR using a beater.
Manila hemp pulp: Softwood pulp = 70:3
An aqueous slurry with a mixing ratio of 0.3% and a concentration of 0.3% was prepared in a container.

The water-insoluble fibrous carboxymethyl cellulose used in Example 1 was added to this slurry in an amount of 1/9 of the total amount of the above pulp, stirred well, and mixed uniformly. was made into paper. The chitosan solution used in Example 1 was diluted twice and applied to this paper using a spray coater directly connected to a net conveyor dryer, and then dried with hot air at 110°C.

As a result, the amount of chitosan attached was 0.8%.

The resulting processed paper did not lose its porosity, had a wax-poured surface strength of 14A, and did not peel at all even after continuous gravure printing.

〔Effect of the invention〕

The processed paper of the present invention is made from papermaking fibers as the main raw material, and can be printed using a rotary printing press, a rotary printing press, etc., while retaining the texture and appearance of Japanese paper, such as porosity, lightness, and flexibility. The effect is that the fibers are sufficiently bonded to prevent paper dust and paper peeling from occurring.

Claims (1)

[Claims] 1. Paper whose essential components are one or more types of papermaking fibers selected from bast fibers and leaf fibers, and a small amount of fibrous water-insoluble carboxymethyl cellulose or its salt, and which contains chitosan on at least the printed surface. Processed paper made by adhering things to it.