JPH04289300A - Multi-layered paper - Google Patents

Abstract

PURPOSE:To produce multi-layered paper improved in the disorder of the smoothness of the paper caused by the employment of thick wall fiber pulp, mechanical pulp or waste paper-regenerated pulp and useful as base paper for printing, recording or coating paper. CONSTITUTION:The above-mentioned purpose is achieved by forming a pulp layer comprising chemical pulp using as a raw material the wood part of KENAFU (an annual plant belonging to the genus Malvaceae Hibiscus cultivated in Australia and the Southeast Asia) on at least one surface of a pulp layer containing at least one from thick wall fiber pulp, mechanical pulp and waste paper-regenerated pulp.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to multilayer paper, which improves the poor smoothness caused by thick-walled fiber pulp, mechanical pulp, and recycled waste paper pulp, and can be used as base paper for printing, recording, or coating. A useful multilayer paper is provided.

0002

[Prior Art] The quality of paper is greatly influenced by the beating method of the pulp contained in the paper stock, the paper making method, etc.
It is no exaggeration to say that it is essentially determined by the characteristics of the pulp used. Characteristics of pulp include fiber length, fiber diameter, inner pore diameter, fiber wall thickness, etc., and these are important factors that determine the quality of paper.

[0003] For example, thick-walled fiber pulp has the property of being rigid and hard to crush, and paper made from paper stock containing this pulp has a small bonding area between fibers and less tangles between fibers. , it becomes bulky and has poor smoothness. In addition, mechanical pulp is used to improve the decrease in opacity associated with weight reduction of paper, but due to the lignin it contains, it is rigid and difficult to crush, and also has poor smoothness. Recycled paper pulp is a raw material that we would like to use as much as possible, considering the issue of resource conservation has been drawing attention in recent years. is progressing and the fibers are becoming hard. Also, since some raw materials contain mechanical pulp, they are difficult to crush and have poor smoothness.

In order to improve the poor smoothness of papers containing these thick-walled fiber pulps and mechanical pulps, Japanese Patent Publication No. 2-42952 and Japanese Patent Application Laid-Open No. 2-91277 disclose methods for improving the paper stock constituting the paper. A method has been disclosed in which a chemical pulp made from the woody part of kenaf (hereinafter simply referred to as kenaf woody chemical pulp) is added, and a considerable improvement effect has been obtained. However, in these methods, since kenaf wood chemical pulp is blended into the paper stock, satisfactory results in improving smoothness cannot necessarily be obtained. In order to improve the smoothness of the paper sheet, there is a method of beating the pulp, but this method results in poor dewatering performance on the paper machine, resulting in a decrease in paper-making speed and poor productivity. Moreover, there is a problem in that the shrinkage rate of the sheet during drying increases and dimensional changes due to changes in humidity become large.

[0005]

SUMMARY OF THE INVENTION The present invention aims to improve the above-mentioned poor smoothness and reduced dimensional stability particularly caused by thick-walled fiber pulp, mechanical pulp, and recycled waste paper pulp.
The present invention provides multilayer paper useful as printing/recording paper or base paper for coating.

[0006]

[Means for Solving the Problems] The present invention provides a pulp layer made of chemical pulp made from the woody part of kenaf on at least one side of a pulp layer containing at least one of thick-walled fiber pulp, mechanical pulp, or recycled waste paper pulp. This is a multilayer paper characterized by having a layer formed as a surface layer.

[0007]

[Operation] The kenaf used in the present invention is an annual herb of the genus Hibiscus in the family Malvaceae cultivated in Australia, Southeast Asia, etc., and is generally used as a fiber raw material for ropes and packaging materials. Techniques have been proposed to pulp them and use them as paper raw materials, and although some of them have been converted into chemical pulp and used, the majority of them are currently used only as mechanical pulp raw materials.

In the present invention, a pulp made from such kenaf as a raw material is used, but rather than being used as a mechanical pulp, the woody part of kenaf is used as a raw material, and this is particularly used after being converted into chemical pulp. Moreover, by covering the pulp layer made of thick-walled fiber pulp, mechanical pulp, and recycled waste paper pulp as part of the paper stock with a pulp layer made of this special kenaf wood-based chemical pulp, it is possible to accelerate beating and increase paper-making speed. This improves the smoothness and dimensional stability of the resulting multilayer paper without any deterioration. The kenaf wood chemical pulp used in the present invention is produced by barking the raw material kenaf to separate the bast, and using the wood as the raw material, it is processed by kraft pulping method, soda pulping method, monkey pulping method, etc. Manufactured by chemical pulping using phytopulping method etc.

[0009] Thick-walled fiber pulp is a pulp consisting of fibers with an inner pore diameter of 50 or less when the fiber diameter is 100,
For example, Southern pine (inner pore diameter 45), Douglas fir (
Examples include pulp made of mangrove (inner pore diameter 25), mangrove (inner pore diameter 25), and the like. Specific examples of mechanical pulp include ground wood pulp (GP), pressurized ground wood pulp (PGW), refined ground wood pulp (RGP), thermomechanical pulp (TMP), and chemically treated pulp. Ground Wood Pulp (CGP), Chem Refiner Ground Wood Pulp (CRGP), Chemothermomechanical Pulp (CT
Examples include unbleached pulp and bleached pulp such as MP). Raw materials for used paper recycled pulp include, for example, top white, ruled white,
Card, special white, medium white, imitation, colored, Kent, white art,
Examples include newspapers, magazines, etc., but used paper recycled pulp is generally processed through a disintegration process, rough selection process, fine selection process,
It is manufactured by a process that appropriately combines a deinking process and a bleaching process.

[0010] In the multilayer paper of the present invention, at least one side of the pulp layer (hereinafter simply referred to as the base pulp layer) containing these thick-walled fiber pulp, mechanical pulp, or recycled waste paper pulp as a part of the paper stock, A pulp layer made of kenaf wood chemical pulp is formed as a surface layer, and this surface layer has a weight of 5 g/m2 or more, preferably 10 g/m2 or more.
/m2 or more is desirable. Incidentally, 5g/m2
If it is less than that, the coverage of the base pulp layer will be insufficient, and the fibers of the base pulp layer may affect the paper surface, making it impossible to obtain sufficient surface smoothness.

[0011] Kenaf wood chemical pulp does not have a fiber length comparable to that of softwood pulp, unlike chemical pulp made from bast, and has a fiber length that is 1/1 that of hardwood pulp.
Since the fiber length is about 2.2 mm and the fibers are thin-walled, they swell considerably even in an unbeaten state. When used as the surface layer of paper like the multilayer paper of the present invention, the fibers on the surface of the base pulp layer Close the gaps, and further demonstrate your own characteristics,
It is estimated that this has the effect of significantly improving smoothness.

The method for producing the multilayer paper of the present invention is not particularly limited, and conventional paper making techniques can be applied as appropriate, but in particular, the multilayer paper making technique using a combination of paper machines as shown below is applicable. It is preferable to manufacture using. That is, as a head box for multilayer papermaking, for example,
Beloit's Strata-Flo, Tampera's Co
This method uses ntro-Flo, HTB-3L manufactured by KMW Co., etc., and forms layered paper layers by flowing out the paper stock constituting each layer in parallel from a stock inlet. In these multilayer papermaking methods using a single headbox, the stock is appropriately mixed at the interface between each paper layer, so compared to the conventional papermaking method, the strength in the Z direction is greater and delamination is reduced. This is because it is possible to make paper that is less likely to generate.

The thus obtained multilayer paper of the present invention may be used as printing paper or copy paper as it is, and may also be used as art paper or coated paper whose surface is coated with paint containing pigments, binders, etc. as main components. It can also be used as base paper for thermal recording paper, pressure-sensitive copying paper, etc. Even when finished into each product, the improvement effects such as the smoothness and dimensional stability of the base paper are sufficiently maintained, and the quality of the final product is maintained. This contributes to

[0014]

[Examples] The present invention will be explained in more detail with reference to Examples below, but the present invention is of course not limited to these. Note that all % and parts in the examples indicate weight % and parts by weight.

Example 1 [Preparation of chemical pulp from kenaf wood part] The wood part was collected from Australian kenaf, and the wood part was kraft-cooked to obtain unbleached pulp. This unbleached pulp was treated with a screen to remove undigested materials, and then treated sequentially with chlorine, sodium hydroxide, sodium hypochlorite, and chlorine dioxide to obtain bleached pulp. The Canadian Standard Freeness (hereinafter simply referred to as CSF) of the obtained pulp is 3.
It was 90cc.

[Preparation of paper stock constituting the surface layer and base pulp layer] Kenaf wood chemical pulp is not beaten, and 0.25% rosin (weight ratio of pulp, the same applies hereinafter) and 3% sulfuric acid are added to it. It was added to form a paper stock that constitutes the surface layer. In addition, bleached kraft pulp (hereinafter simply referred to as BKP) produced from commercially available southern pine was refined using a double disc refiner to obtain a refined raw material of 550 cc of CSF. Separately, broad-leaved BKP was beaten to 500 cc of CSF and mixed at a ratio of 70% with 30% of the above Southern pine BKP. and,
0.25% of rosin and 3% of sulfuric acid were added to this to prepare a paper material constituting the base pulp layer.

[Manufacture of multilayer paper] The paper stock prepared above is
A multi-layer paper machine with a multi-layer head box, each surface layer weighs 10 g/m2 and the base pulp layer weighs 4 g/m2.
Three-layer paper was made so that the weight was 3 g/m2. Then, an aqueous solution of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) was size-pressed to a dry solid content of 1.5 g/m2, processed with a machine calender, and finished with a weight of 64 g/m2. A multilayer paper was obtained.

Example 2 A multilayer paper was obtained in the same manner as in Example 1, except that the southern pine in Example 1 was replaced with mangrove BKP.

Example 3 The surface area of Example 1 had a weight of 5 g/m2,
A multilayer paper was obtained in the same manner as in Example 1, except that the basis weight of the base pulp layer was 53 g/m2.

Example 4 A multilayer paper was obtained in the same manner as in Example 1, except that the southern pine used in Example 1 was replaced with bleached GP refined to 100 cc of CSF using a single disc refiner.

Example 5 Multilayer paper was obtained in the same manner as in Example 1, except that the southern pine used in Example 1 was replaced with DIP, which was made from old newspaper that had been refined to 250 cc of CSF using a single disc refiner.

Example 6 Waste newspaper D obtained by refining 30% of the southern pine from Example 1 to 250 cc of CSF using a single disc refiner.
Changed to IP70% and hardwood BKP70% to CSF
A multilayer paper was obtained in the same manner as in Example 1, except that 500 cc of softwood BKP was changed to 30%.

Comparative Example 1 The surface area of Example 1 had a weight of 3 g/m2,
A multilayer paper was obtained in the same manner as in Example 1 except that the basis weight of the base pulp layer was 57 g/m2.

Comparative Example 2 DIP20.5 of used newspaper beaten to CSF250cc
%, 47.8% of hardwood BKP with 500cc of CSF, and 31.7% of the kenaf wood chemical pulp used in Example 1 were mixed, and 0.25% of rosin and 3% of sulfuric acid were added thereto. Fourdrinier paper machine yields 63g/m2
The paper was made to look like this. Then, an aqueous solution of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) was size-pressed to a dry solid content of 1.5 g/m2, and treated with a machine calender, resulting in a finished product weighing 64 g/m2.
A paper sheet of m2 was obtained.

Comparative Example 3 CSF500cc of hardwood BKP70% and CSF500
A paper stock prepared by mixing 30% beaten Southern Pine BKP with cc and adding 0.25% rosin and 3% sulfuric acid was made into paper using a fourdrinier paper machine to give a paper weight of 63 g/m2. And oxidized starch (product name: Ace A,
Oji Cornstarch Co., Ltd.) aqueous solution with a dry solid content of 1
．． It was size pressed to a weight of 5 g/m 2 and treated with a machine calender to obtain a finished paper sheet with a weight of 64 g/m 2 .

Comparative Example 4 A paper sheet was obtained in the same manner as in Comparative Example 3, except that Southern Pine BKP in Comparative Example 3 was changed to Southern Pine BKP beaten to 300 cc of CSF.

[Preparation of coated paper] Kaolin (product name: U
W-90, made by EMC) 80 parts, heavy calcium carbonate (
Product name: Softon 1800, manufactured by Bihoku Funka Kogyo) 10 copies,
10 parts of Sachin White and 0.1 part of sodium hydroxide,
Disperse 0.3 parts of sodium polyacrylate using a Coles disperser, add 5 parts of oxidized starch, 13 parts of styrene-butadiene latex, and 0.05 parts of a silicone antifoaming agent, and stir and mix to obtain a solid content concentration of 60. % coating composition was prepared. Next, this coating composition was coated on both sides of the multilayer paper and paper sheet obtained in the above Examples and Comparative Examples with a blade coater so that the dry solid content was 20 g/m2 per side, and then with a dryer. After drying, it was treated with a super calender to obtain double-sided coated paper.

[Preparation of thermal recording paper] 10 parts of 3-(N-cyclohexyl-N-methylamino)-6-methyl-7-phenylaminofluorane, 20 parts of methyl cellulose (5% aqueous solution) and 10 parts of water were sand milled. Pulverize until the average particle size is 3 μm to obtain liquid A, and add bisphenol A.
30 parts of methyl cellulose (5% aqueous solution) and 20 parts of water were ground in a sand mill until the average particle diameter was 3 μm to obtain liquid B. Next, 40 parts of liquid A, 80 parts of liquid B, 30 parts of silicon oxide pigment (oil absorption: 180cc/100g),
A coating composition for heat-sensitive recording prepared by stirring and mixing 100 parts of a 20% oxidized starch aqueous solution and 70 parts of water was applied to the multilayer paper and paper sheet obtained in the above Examples and Comparative Examples, each having a dry solid content of 7 g. /m2, and after drying, it was treated with a super calender to obtain heat-sensitive recording paper.

[Preparation of pressure-sensitive copying paper] "Preparation of top paper" 20% of a copolymer consisting of 15 mol% vinyl sulfonic acid, 5 mol% styrene, 70 mol% acrylic acid, and 10 mol% ethyl acrylate. Add 112.5 parts of water to 37.5 parts of aqueous solution, and adjust the pH with 20% NaOH aqueous solution.
The aqueous medium adjusted to 4.6 was used as an aqueous medium for capsule production. To this was added 105 parts of diisopropylnaphthalene (trade name: K-113, manufactured by Kureha Chemical Co., Ltd.) in which 5 parts of crystal violet lactone had been dissolved, and after emulsifying and dispersing it so that the average particle size was 5 μm, the temperature of the emulsion was lowered. The temperature was raised to 70°C. Next, 20 parts of methylated methylolmelamine initial condensate (trade name: Beckamine APM, 80% concentration, manufactured by Dainippon Ink Chemical Co., Ltd.) was added to the system, and the temperature of the system was maintained at 70°C for 1 hour while stirring. After being held, it was cooled to obtain a milky white capsule dispersion. A capsule coating liquid prepared by adding 70 parts of wheat starch and 20 parts of dissolved oxidized starch (solid content) to this capsule dispersion liquid was applied to the multilayer paper and paper sheet obtained in the above Examples and Comparative Examples, each with a dry solid content. 4g/m2
It was coated on one side and dried to obtain a top sheet for pressure-sensitive copying paper.

"Preparation of bottom paper and middle paper" A mixture of 65 parts of aluminum hydroxide, 20 parts of zinc oxide, zinc 3,5-di(α-methylbenzyl)salicylate and α-methylstyrene/styrene copolymer. 15 parts of melt (melt ratio 80/20),
5 parts of polyvinyl alcohol aqueous solution (solid content) and 30 parts of water
A color developer coating solution prepared by adding 20 parts (solid content) of carboxyl-modified styrene-butadiene copolymer latex to a dispersion obtained by grinding 0 part with a ball mill for 24 hours,
The multilayer paper and paper sheet obtained in the above examples and comparative examples were coated on one side so that the dry solid content was 4 g/m2, respectively.
After drying, a lower sheet for pressure-sensitive copying paper was obtained. Then, on the side opposite to the color developer coated side of the bottom paper, apply the capsule coating liquid used in making the top paper, each with a dry solid content of 4 g/m2.
It was coated and dried to obtain a medium leaf for pressure-sensitive copying paper.

"Quality Test" [Water immersion elongation] The water immersion elongation of the multilayer papers and paper sheets obtained in the Examples and Comparative Examples was determined by J. TAPPI No. 27, and the results are listed in Table 1. [Smoothness] The smoothness of the multilayer papers and paper sheets obtained in Examples and Comparative Examples was measured according to the JIS P 8138 method, and the smoothness of the coated paper was measured using a Smoother smoothness tester (manufactured by Toei Electronics Co., Ltd.). ), and the results are listed in Table 1. [Ink smoothness] Black ink was printed on coated paper using an RI printing tester (manufactured by Mei Seisakusho Co., Ltd.), and the smoothness of the printed surface was visually evaluated. The evaluation criteria were [○: good, △: slightly poor, ×: poor].

[0032]

[Table 1]

[Evaluation of thermal recording paper] Printing was performed using an ultra-high speed thermal printer (UP-103, manufactured by Sony Corporation) at a head voltage of 15.5 volts and a pulse width of 6 ms, and the image density was measured using a Macbeth densitometer. . In addition, background stains on the surface of the recording layer were visually determined. The evaluation criteria were as follows: [◎: Excellent, ○: Slight stains observed, △: Stain stains observed, ×: Significant stains observed]. Furthermore, the sharpness of the recorded image was visually judged. In this case, the evaluation criteria were [◎: extremely excellent, ◯: good, △: slightly poor]. The evaluation results are listed in Table 2.

[0034]

[Table 2]

[Evaluation of pressure-sensitive copying paper] The middle paper and the bottom paper were stacked so that the capsule-coated surface of the middle paper and the developer-coated surface of the bottom paper faced each other, and a load of 600 kg/cm2 was applied. The color image obtained was measured using a Macbeth densitometer to evaluate color development. In addition, the middle paper and the bottom paper were stacked so that the capsule-coated surface of the middle paper and the color developer-coated surface of the bottom paper faced each other, and a load of 4 kg/cm2 was applied.
The samples were rubbed together several times, and the extent of colored stains on the surface coated with the color developer was visually determined. The judgment criteria are [◎: Extremely good, ○
: Some stains are observed; ×: Significant stains are observed. The evaluation results are listed in Table 3.

[0036]

[Table 3]

[0037]

Effects of the Invention As is clear from the results in the table, all of the multilayer papers obtained in the examples of the present invention have greatly improved smoothness, and coated paper using this multilayer paper as a base paper The smoothness of the paper and the smoothness after printing were also improved. Also,
Thermal recording paper using this multilayer paper as a base paper can produce clear and excellent recorded images without causing background stains.
The pressure-sensitive copying paper had an extremely good balance between color development ability and color development stains.

Claims (4)

[Claims] Claim 1: A pulp layer made of chemical pulp made from the woody part of kenaf is formed as a surface layer on at least one side of a pulp layer containing at least one of thick-walled fiber pulp, mechanical pulp, or recycled waste paper pulp. Features multilayer paper. 2. The multilayer paper according to claim 1, wherein the surface layer is made of chemical pulp made from the woody part of kenaf and has an amount of 5 g/m 2 or more. 3. The multilayer paper for printing and recording according to claim 1 or 2, wherein printing or recording is performed on the surface layer made of chemical pulp made from the woody part of kenaf. Claim 4: Claim 1 or 2, wherein various coating materials are applied to the surface layer made of chemical pulp made from the woody part of kenaf.
Multilayer paper for coating base paper as described.