JPH048580A - Pressure-sensitive copying paper - Google Patents

Abstract

PURPOSE:To obtain superior running properties and eliminate a shift in gathering in a collator and an occurrence of skew by using base paper having a specific relation of a thermal shrinkage coefficient in a paper making direction and a thermal shrinkage coefficient in a width direction as a substrate. CONSTITUTION:Where a thermal shrinkage coefficient in a paper making direction in base paper is DELTAT and a thermal shrinkage coefficient in a width direction is DELTAW, base paper having a relation of 0.40<=DELTAW/DELTAT<=0.70, preferably 0.45 <=DELTAW/DELTAT<=0.65, and more preferably 0.48<=DELTAW/DELTAT<=0.60 is used. A skew in the qualities of NIP paper which is related to a fiber orientation of the base paper cannot be demonstrated by a thermal shrinkage only in one direction. This is why the thermal shrinkage coefficient of the base paper is shown by a ratio of DELTAT to DELTAW in two directions, i.e., a paper making direction and in width direction. When DELTAW/DELTAT is less than 0.40, a large thermal shrinkage in paper making direction causes problems of running properties in NIP and a shift in gathering in a collator as a post handling. When DELTAW/ DELTAT is more than 0.70, a skew occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to pressure-sensitive copying paper, and particularly to pressure-sensitive copying paper that is highly suitable as output paper for non-impact printers (NIP).

``Prior art'' Pressure-sensitive copying paper is made of a base paper coated with a layer containing microcapsules containing an electron-donating dye on one side, and an electron-accepting compound that develops color when it comes into contact with the electron-donating dye. Lower paper coated with a layer containing (color developer), inner paper coated with a layer containing microcapsules on one side of the base paper and a layer containing a color developer on the other side, and even the same side of the base paper. Self-coloring papers are known in which microcapsules and color developers are laminated or mixed, and these are used in appropriate combinations.

In recent years, as computers have become larger and the amount of information processed has increased, output printers have become faster, more versatile, and more versatile.
Low noise has been required, and non-impact type printers (NIP) are widely used in place of conventional impact type printers.

Up until now, forms output from computers have been difficult to read because they are expressed in katakana or English characters, and there is also a potential high demand for printouts in kanji, so high-speed kanji printouts are possible. This is one reason why the use of non-impact printers is rapidly increasing.

The number of forms in which pressure-sensitive copy paper is used as NIP paper is increasing. For example, after printing out the top paper, middle paper, and bottom paper of pressure-sensitive copy paper using NIP, the top, middle, and bottom paper are printed out using a collator, etc. It is used to compile forms and create contracts, etc.

The mainstream of NIP is electrophotography, which uses laser light to form a latent image on a photosensitive drum based on information from a computer, develops it with toner, and transfers it to paper.
There is a method of heat fixing using a heat roll, or a method of fixing using a flash lamp or cold fusion.

In the heat roll method, heat of 180 to 200°C is applied to the paper, and in the flash lamp method, heat of 70 to 80''C is applied to the paper.This has the drawback of causing troubles due to thermal deformation of the paper.

The qualities that NIP paper should have are: - Good foldability in a stacker. In particular, so-called "skewing", that is, a phenomenon in which the shapes of folded sheets become misaligned when stacked on top of each other, does not occur.

■ Good printing suitability and sufficient electrical properties and surface properties to withstand high-speed printing.

■ Good toner adhesion.

■ No paper dust or curling occurs.

etc.

When pressure-sensitive copying paper is used as NIP paper, in addition to the above-mentioned items 1 to 2, it must also have no odor.

■ The function as pressure-sensitive copying paper is not impaired.

■ Dimensional stability is good, and no deviation occurs when the collator is adjusted.

is added.

As for pressure-sensitive copying paper, if you are trying to make a large number of copies, the thinner the paper is, the better, but then it becomes more difficult to control skew and expansion/contraction, so it is better to have a good balance of NIP suitability and pressure-sensitive copy suitability. At present, pressure-sensitive copying paper for NIP has not been developed.

On the other hand, with the recent progress in office automation (OA), contrary to what was said to be a "paperless" society, large amounts of information paper called OA paper are being discharged from offices and factories, and newspapers The consumption of coated paper for printing is rapidly increasing due to the increasing use of visual inserts, magazines, and advertisements, as well as the use of color and luxury. It has become a social problem.

However, if valves made from recycled waste paper are used as a raw material for office automation paper, coated paper for printing, and uncoated paper, quality problems may occur, so valves are not fully utilized as raw materials for these materials. . Furthermore, there is a limit to the amount of recycled paper that can be used as a raw material for conventional newspapers and cardboard. In particular, waste paper such as office automation paper and coated paper for printing, which is difficult to recycle, is actually collected and incinerated, which increases the cost of incineration in each local government, issues with landfill and other processing capacity, and even causes problems for the planet. It has developed into an international environmental issue such as resource protection and forest resource decline issues.

Therefore, there is a strong demand for establishing a method for reusing waste paper pulp as a raw material for OA paper, coated paper for printing, uncoated paper, and the like. However, most of the used office paper such as printer paper for office computers, personal computers, word processors, Funks, etc. and copy paper are printed with toner containing resin components, and offset printing of printing paper also uses resin components. Because the paper is printed with a large amount of printing ink (particularly in the case of rotary offset printing), it is difficult to remove colored prints and printing pigments from the paper.

For this reason, various methods have been proposed for collecting waste paper such as office automation paper and printing paper.In particular, a hydrophilic surfactant-based deinking agent is used, and a machine is used to apply compressive force to the waste paper using a kneader or disperser. The so-called high-density kneading system method (hereinafter referred to as the HDK method), which performs deinking by applying agitation, is attracting attention because of its excellent deinking effect.

However, the recycled pulp obtained by this HDK method is
Because it is strongly treated with a special surfactant under heat and pressure, the resulting recycled pulp exhibits physical properties that are quite different from ordinary pulp fibers, making it possible to produce recycled pulp that does not involve the conventional virgin pulp or HDK method. Furthermore, it is difficult to control the expansion and contraction stability against heat compared to base paper obtained by blending simple recovered pulp obtained from common loss paper at paper mills and unprinted waste paper, and it is difficult to control the expansion and contraction stability against heat, making it difficult to control pressure-sensitive copying for NIP. Currently, paper is not fully utilized.

"Problem to be Solved by the Invention" The present invention has excellent runnability when used as output paper for a non-impact printer (NIP).
It is an object of the present invention to provide a pressure-sensitive copying paper which does not cause misregistration or skew in the collator and has excellent coloring ability without coloring stains.

"Means for Solving the Problems" The present invention provides a pressure-sensitive copying paper that utilizes a color-forming reaction between an electron-donating color former and an electron-accepting color developer. The thermal contraction rate ΔW in the direction is 0.4
This pressure-sensitive copying paper is characterized by using a base paper having a relationship of 0≦ΔW/ΔT≦0.70.

The present invention is based on the Clark stiffness of base paper (JIS P-8143,
A pressure-sensitive copying paper having a thickness of 10 cm or more (Method A) is disclosed.

The present invention also discloses a pressure-sensitive copying paper in which the base paper contains recycled pulp made from waste paper.

Furthermore, the pressure-sensitive copying paper described above is disclosed, wherein the recycled pulp is a recycled pulp obtained by a deinking process that includes a mechanical stirring step in which compressive force is applied to waste paper in the presence of a surfactant-based deinking agent.

"Function" An important factor in the quality of pressure-sensitive copying paper for NIP is its stability against heat expansion and contraction. The inventors of the present invention have determined the quality of pressure-sensitive copying paper for NIP as a result of various studies on the ratio of the heat shrinkage rate in the papermaking direction and the heat shrinkage rate in the width direction as an index of the expansion and contraction stability of pressure-sensitive copying paper for NIP. I found out that it can be done. In other words, the thermal shrinkage rate of the base paper in the papermaking direction is ΔT
, when the heat shrinkage rate in the width direction is ΔW, 0.40≦ΔW/
ΔT≦0.70, more preferably 0.45≦ΔW/ΔT
≦0.65, more preferably 0.48≦ΔW/ΔT≦0
．． The above problem can be solved by using No. 60 base paper.

The thermal shrinkage rate of the base paper as used in the present invention is the rate of change in length (%) when the base paper is held at a high temperature of 110° C. for 3 minutes.

The reason why the thermal shrinkage rate of the base paper was calculated as the ratio of the paper making direction ΔT and the width direction ΔW is because the slant of the quality of NIP paper is related to the fiber orientation of the base paper. This is because it cannot be discussed in terms of contraction.

Incidentally, if ΔW/ΔT is less than 0.40, heat shrinkage in the papermaking direction will be large, causing problems with runnability in NIP and balance in the collator, which is a subsequent process, and if ΔW/ΔT is 0.
．． If it exceeds 70, a tilt occurs.

The ΔW/ΔT of base paper can be controlled by, for example, pulp composition, beating conditions, type and amount of filler added, paper strength agent, internal sizing agent, pH1 surface sizing agent, surface treatment agent, paper density,
This is achieved by appropriately adjusting various conditions such as wire mesh, hydrofoil arrangement, jet/wire ratio of the paper machine, wire shaking, paper filler distribution, smoother pressure conditions, press pressure conditions, and drying temperature conditions. be done. However, since the various conditions mentioned above affect the paper making speed, it is natural that the optimum conditions should be selected as appropriate depending on the paper machine used.

Specifically, (1) the Jet/Wire ratio during paper making is increased, and the fiber orientation is made irregular to reduce the heat shrinkage rate in the width direction.

■Make the draw as weak as possible during paper making to reduce stress on the width method when wet. - Reduce the degree of expansion and contraction after paper making by reducing the degree of beating, suppressing fibrillation of fibers, and reducing entanglement of fibers. ■DIP, BCTM
Particularly effective methods include blending pulp such as P, TMP, and CP and using fibers with little swelling.

In the pressure-sensitive copying paper of the present invention, the ΔW/Δ of the base paper is as described above.
T is adjusted to a specific range, but it is also desirable for NIP paper to adjust the Clarity stiffness (JIS P) of the base paper.
-8143, A method) is 10 cm or more, more preferably 12 cm or more. If the Clark stiffness is less than 10 cm, the suitability for folding in a stunker will be somewhat poor, and jamming may occur.

Clark stiffness may be controlled by appropriately selecting a known method. Specifically, ■Reduce the ash content in the base paper.

■Increase the blending rate of NBKP in the pulp composition. Measures such as lowering the tension of the zero paper are effective.

As the base paper of the pressure-sensitive copying paper of the present invention, a base paper containing recycled pulp of waste paper can be used.

Base paper containing recycled waste paper pulp has more keratinization than base paper made only of virgin pulp, and fibers that have undergone carbon thermal deformation do not deform any further when exposed to new heat, so they have excellent NIP suitability. This has the advantage of providing pressure-sensitive copying paper with high quality.

Recycled paper pulp is generally obtained by appropriately combining a disintegration process, a rough selection process, a fine selection process, a deinking process, and a bleaching process. Low concentration pulper, high concentration pulper, etc. are used in the disintegration process, screens, cleaners, etc. are used in the rough selection process and fine selection process, and flotation method, main selection method, compromise method, etc. are used in the deinking process. be selected depending on the quality of the material.

Traditionally, deinking methods include using a combination of sodium sulfite and caustic soda, earth kettle high-pressure cooking and cleaning method, solvent method, pulper immersion cleaning method, pulper immersion flotation method, etc.
The method used was to dissolve or emulsify printing ink, resin, etc. using chemicals or heat.

On the other hand, the HDK method (high-density kneading system method) is a waste paper processing method in which a surfactant is added to a high-density paper stock of about 15% or more, and the process is performed using strong and uniform interfiber friction similar to kneading. , separates printing ink from pulp fibers,
A method in which foreign substances such as printing ink are uniformly made into ultra-fine particles and removed by the flotation method [Paper Bag Technical Association Magazine 1986 6]
Monthly issue, pages 1 to 17, Paper and Pulp Technology Times, August 1988 issue, pages 25 to 31, and Japanese Patent Publication No. 11353/1983].

In particular, refiner, kneader 1
The pulp obtained by deinking waste paper, which includes a process of mechanically treating it while applying compressive force using a twin-shaft mixer, divider, etc., has a good deinking rate of printing ink, etc., and can yield recycled pulp with high whiteness. Therefore, it is preferable.

As the deinking agent, commonly used surfactants can be used, and among them, surfactants made of fatty acid soaps, fatty acids, and fat-based adducts of ethylene oxide and propylene oxide are exemplified.

In addition, as a surfactant, a surfactant having an HLB value of 11 to 14 is preferable because a high degree of whiteness can be obtained.

The waste paper used as raw materials includes information-related paper such as uncoated printer paper for computers, personal computers, word processors, fax machines, etc., printer paper such as thermal paper and pressure-sensitive copy paper, and so-called OA waste paper such as Xerox copy paper. , art paper, coated paper, lightly coated paper, coated paper such as matte paper, as well as high-quality paper, high-quality colored paper, notebooks, stationery, wrapping paper, fancy paper, medium-quality paper, newsprint, receiving paper, and super paper. Hanging paper, imitation paper, pure white roll paper, uncoated paper and paperboard such as milk cartons, acidic or neutral paper, chemical pulp paper, high-yield pulp (SOP, BSGP, BCTMP, TMP)
, RGP, CNP, etc.) can be used, and there are no particular limitations.

Please note that if the obtained recycled pulp is blended without treatment, the smoothness of the base paper surface and the paper strength of the base paper may decrease.
It is preferable that the paper be treated with a beating machine in the pre-process of the paper machine to reduce the Canadian Standard freeness in the range of about 30 to 150 cc. In addition, as a refining machine, a conical refiner, a single disc refiner, a double disc refiner, etc. are used.
In consideration of power, it is more preferable to use a double disc refiner.

The base paper thus obtained is coated with a microcapsule-containing coating liquid or a color developer-containing coating liquid according to a conventional method to be finished as top paper, bottom paper, inner paper, self-coloring paper, etc. However, the method of applying the coating liquid is not clear. is not particularly limited, and a coating liquid having a dry weight of about 2 to 10 g/m 2 is applied and dried using a suitable coating device such as an air knife coater, roll coater, blade coater, rod coater, or curtain coater.

Microcapsule-containing coating liquids generally include triarylmethane lactones, spiropyrans, fluorans,
Basic dyes such as diphenylmethanes and azine gB can be extracted from synthetic oils such as alkylated naphthalene, alkylated diphenyl, alkylated diphenylmethane, and alkylated terphenyl, vegetable oils such as cotton oil and castor oil, animal oils, mineral oils, or mixtures thereof. The microcapsules are prepared by dissolving them in a solvent and incorporating them into microcapsules by each of the 11 capsule manufacturing methods such as the coacervation method, interfacial polymerization method, and 1n-situ method, and further adding a binder and the like.

In addition, color developer-containing coating liquids generally include inorganic color developers such as acid clay, activated clay, and attapulgide, various aliphatic carboxylic acids, benzoic acid, p-tert-butylbenzoic acid,
Phthalic acid, salicylic acid, 3-isopropylsalicylic acid,
3-phenylsalicylic acid, 3-cyclohexylsalicylic acid, 3-methyl-5-(α-methylhensyl)salicylic acid, 3-methyl-5-(α,α-dimethylhensyl)salicylic acid, 3.5-di-5ec-butylsalicylic acid ,3,
5-tert-butylsalicylic acid, 3,5-tert-butyl-6-methylsalicylic acid, 3-t
erbutyl-5-phenylsalicylic acid, 3,5-di-t
er tAmylsalicylic acid, 3,5-dicyclohexylsalicylic acid, 3-cyclohexyl-5-(α-methylbenzyl)salicylic acid, 3-dodecylsalicylic acid, 3-methyl-5-dodecylsalicylic acid, 3-dodecyl-5- Methylsalicylic acid, 3-dodecyl-6-methylsalicylic acid, 3-phenyl-5-(α-methylbenzyl)salicylic acid/3-phenyl-5-(α,α-dimethylhensyl)
Salicylic acid, 3-(α-methylbenzyl)-salicylic acid, 3-(α-methylbenzyl)-5-methylsalicylic acid, 3-(α-methylbenzyl)-5-phenylsalicylic acid, 3-(α,P-tolylethyl) -5 Methylsalicylic acid, 3.5-di(α,p-tolylethyl)-salicylic acid, 3-(α,α-dimethylhensyl)-5-methylsalicylic acid, 3-(α,α-dimethylhensyl)-6 -Methylsalicylic acid, 3,5-di(αα-dimethylbenzyl)salicylic acid, 3,5-di~ (α-methylbenzyl)
Salicylic acid, 3-(α~methylbenzyl)-5~ (α
, α-dimethylbenzyl)salicylic acid, 3-(α-methylhensyl)-5-bucomosalicylic acid, 3-(α-methylbenzyl)-4-methylsalicylic acid, 3-(α-methylbenzyl)-6methylsalicylic acid, 3 -nonylsalicylic acid, 3-nonyl-5-methylsalicylic acid, 3-nonyl-6-methylsalicylic acid, 3-nonyl-5-phenylsalicylic acid, 3-methyl-5-nonylsalicylic acid, 5-(4
-Mesitylmethylbenzyl) salicylic acid, pinene salicylic acid, hensylated styrenated salicylic acid, 2-hydroxy-3-(α,α-dimethylbenzyl)-1-naphthoic acid, 3-hydroxy-2-naphthoic acid, 3-hydroxy Aromatic carboxylic acids such as -7-(α,α-dimethylbenzyl)-2-naphthoic acid, p-phenylphenol-
Organic color developers such as phenolic resins such as formalin resin and p-butylphenol-acetylene resin, and furthermore, combinations of these organic color developers and polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, and nickel. It is prepared by dispersing various color developers such as salts in a binder.

Examples of binders include starches, celluloses, proteins, gum arabic, polyvinyl alcohol, styrene-maleic anhydride copolymer salts, styrene-butadiene copolymer emulsions, acetic acid and maleic anhydride copolymer salts, and polyvinyl alcohol. Acrylates and the like are appropriately selected and used.

For pressure-sensitive copying paper, see, for example, U.S. Pat. No. 2,505.
No. 470, No. 2.505.471, No. 2,505,4
No. 89, No. 2, 548.366, No. 2,712.50
No. 7, No. 2,730.456, No. 2,730.457
As described in No. 3,418.250, No. 3,924,027, No. 4,010,038, etc., there are six types of forms, and the present invention is applicable to these various forms. It can be applied to pressure-sensitive copying paper.

The pressure-sensitive copying paper of the present invention uses the above-mentioned specific base paper as a base paper, but in the case of a transfer-type pressure-sensitive copying paper that uses an appropriate combination of top paper, middle paper, and bottom paper, Even if a specific base paper is used only in part, the desired effect can be obtained.

``Example J'' The present invention will be described in more detail with reference to Examples below, but the present invention is of course not limited to these.

In addition, parts and % in the examples indicate parts by weight and % by weight, respectively, unless otherwise specified.

Example 1 ■ Preparation of base paper Canadian Standard Freeness 500cc LB
Talc was added to a pulp suspension prepared by blending 80 parts of KP and 20 parts of NBKP so that the paper ash content was 6%, and rosin size was added as a sizing agent at 1.4% based on the bone-dry pulp.

After adjusting the pH of this pulp slurry to 4.6 with a sulfuric acid band, paper was made using a long multi-cylinder cylinder dryer paper machine, and 1.5 g of an aqueous solution of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) was added to the pulp slurry. size press so that it becomes
(A base paper for pressure-sensitive copying paper was obtained. ΔW/Δ of this base paper
T was 0.55, and Clark stiffness was 13.5 cm.

■ Preparation of top paper Add 37.5 parts of a 20% aqueous solution of a copolymer consisting of 15 mol% vinyl sulfonic acid, 5 mol% styrene, 70 mol% acrylic acid, and 10 mol% ethyl acrylate to 112.5 parts of water. , pH was adjusted to 4°6 with 20% sodium hydroxide aqueous solution.
The aqueous medium for capsule production was adjusted to .

To this was added 105 parts of diisopropyl naphthalene (trade name: Ni 113, manufactured by Kureha Chemical Co., Ltd.) in which 75 parts of Crystal High Olene Tract 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 precondensate (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.

Add 70 parts of wheat starch and 2 parts of dissolved oxidized starch to this capsule dispersion.
A capsule coating solution prepared by adding 0 parts (solid content) was coated on the above-mentioned base paper to a dry weight of 4 g/rrf and dried to prepare a top paper for pressure-sensitive copying paper.

■ Preparation of bottom paper and inner paper [Preparation of color developer dispersion] 100g of 3.5-di(α-methylbenzyl)zinc salicylate (softening point 72°C) and 100g of toluene were added to 70g of
The mixture was mixed and dissolved at °C to prepare a toluene solution.

Separately, 300 g of water containing 6 g of polyvinyl alcohol with a degree of polymerization of 1700 and a degree of saponification of 98% was placed in a stainless steel beaker with an internal volume of 1000 d, and a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) was heated at 3000 per minute. The above toluene solution was added to this while stirring with rotation.

After adding the toluene solution, increase the rotation speed to 1000 per minute.
The temperature was increased to 0 and stirred for 2 minutes. This dispersion was transferred to a hard glass three-necked flask with an internal volume of 1000 d and equipped with a stirrer, a thermometer, and a distillation port. The flask was heated while rotating the stirrer slowly so that toluene and water were distilled out from the distillation port. After continuing this operation at 100°C for about 1 hour, the dispersion contained almost no toluene. This was cooled to obtain an aqueous dispersion containing about 33% of the color developer.

The average particle diameter of the obtained developer-dispersed particles was 1.0 μm.

Next, this aqueous dispersion was processed with a sand grinder (manufactured by Igarashi Kikai Co., Ltd., MODEL NO. 03G-8G) at a rate of 2 kg/min to prepare a color developer dispersion having an average particle size of 0.97 μm. .

[Preparation of color developer coating liquid] 15 parts of the 33% color developer dispersion obtained in the above treatment, 70 parts of calcium carbonate, 10 parts of zinc oxide, and 100 parts of water were mixed and dispersed, and further 10% as a binder was added. 100 parts of polyvinyl alcohol aqueous solution, 50% carboxy-modified S
A developer coating solution was prepared by mixing and dispersing 20 parts of BR latex (SN-307, manufactured by Jumanoga Tank Co., Ltd.) and 200 parts of water.

[Manufacture of bottom paper and middle paper]

Apply the above color developer coating liquid to one side of the above base paper at a dry weight of 6 g/
A base sheet for pressure-sensitive copying paper was prepared by coating and drying to obtain rrf.

Next, the capsule coating liquid was applied to the surface opposite to the developer-coated surface of the lower paper to a dry weight of 4 g/rrr and dried to prepare an inner sheet for pressure-sensitive copying paper.

A performance comparison test was conducted using the top paper, middle paper, and bottom paper thus obtained, and the results are listed in Table 1.

Example 2 A mixture of OA waste paper, high-quality coated paper, and non-coated printed paper was disintegrated in an alkaline aqueous solution using a pulper, screened to remove foreign substances such as plastics and adhesives, and made into pulp. It was dehydrated to a concentration of 30%. In addition, NaOH 3%, NazSi0 34%, H2O
23%, surfactant-based deinking agent [trade name: 01600.
[manufactured by Kao Corporation] 0.4% was added, and the mixture was compressed and stirred using a heating kneader, and then held at about 60°C for 2 hours. Next, about 1
%, deinked by flotation treatment, and dehydrated to obtain recycled pulp with a whiteness of 78% and a freeness of 550 cc.

50 parts of this recycled pulp has a freeness of 500 parts each.
Talc was added to the pulp suspension obtained by blending 30 parts of LBKP and 20 parts of NBKP beaten in cc, and the ash content was 6.
%, and furthermore, rosin size was added as a sizing agent at 1.6% based on the bone dry pulp.

After adjusting the pH of this pulp slurry to 4.6 with sulfuric acid band, paper was made using a fourdrinier cylinder dryer paper machine, and 1.5 g of an aqueous solution of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) was added to the pulp slurry. /rrf, then press the metal roll and elastic roll (Shore D hardness 9).
A base paper for pressure-sensitive copying paper having a basis weight of 50 g/%, a ΔW/ΔT of 0.65, and a Clark stiffness of 14.5 cm was obtained.

Pressure-sensitive copying paper was prepared in the same manner as in Example 1, except that this base paper was used, and a performance comparison test was conducted, and the results are listed in the table.

Example 3 200 cc of freeness recycled pulp made from newspaper was refined using a double disc refiner to produce 150 cc of freeness.
It was set as the freeness of c. To a pulp suspension obtained by blending 50 parts of this recycled pulp with 30 parts of LBKP and 20 parts of NBKP, each beaten to a freeness of 500 cc, talc was added so that the paper ash content was 6%, and rosin size was added as a sizing agent. 1 for bone dry pulp.
Added 0%.

After adjusting the pH of this pulp slurry to 4.6 with a sulfuric acid hand, paper was made using a long multi-cylinder cylinder dryer paper machine, and 1.5 g of an aqueous solution of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) was added to the pulp slurry. size press so that it becomes rrf, metal roll and elastic roll (Shore D hardness 9
A base paper for pressure-sensitive copying paper having a basis weight of 50 g/rrf, a ΔW/ΔT of 0.68, and a Clark stiffness of 14.9 cm was obtained.

Pressure-sensitive copying paper was prepared in the same manner as in Example 1, except that this base paper was used, and a performance comparison test was conducted, and the results are listed in the table.

Example 4 A mixture of used newspaper and printed paper was disintegrated in an alkaline aqueous solution using a pulper, foreign substances such as plastics and adhesives were removed using a screen, and water was dehydrated to a bulb concentration of 25%.

To this, NaOH2%, NazSio,
4%, HzOz3%, surfactant-based deinking agent [product name: DI 600R, manufactured by Kao Corporation] 0.4%, surfactant-based deinking agent [product name: DI 300. Manufactured by Kao Corporation] 0.3
%, and after compression stirring treatment with a heating kneader, about 7
It was kept at 0°C for 2 hours. Then, after further kneading treatment, it was diluted to about 1%, deinked by flotation treatment, and dehydrated to achieve a whiteness of 72% and a freeness of 350.
cc recycled pulp was obtained.

This recycled pulp was refined in a double disc refiner to a freeness of 250 cc, and 70 parts were made into NBKP30, which was refined to a freeness of 500 cc.
To the pulp suspension prepared by blending the above ingredients, heavy calcium carbonate was added so that the paper ash content was 6%, 0.5% of sulfate and 0.5% of cationic starch were added, and further as a sizing agent. Alkyl ketene dimer [trade name: Vercon, manufactured by Dick Vercules] 0.1%, polyacrylamide as a fixing agent [trade name: Percoll 155]
．． (manufactured by Allied Colloid) 0.02% was added.

The thus prepared pulp slurry with a pH of 8.0 was made into paper using a fourdrinier cylinder dryer paper machine, and 100 parts of oxidized starch and 2 parts of an acrylic surface sizing agent (trade name: Polymaron 482, manufactured by Arayo Kagaku Co., Ltd.) were added. 2g/-m”
It was size pressed and treated with an on-machine calendar consisting of a metal roll and an elastic roll (Shore D hardness 78 degrees) to give a basis weight of 50 g/bo and a ΔW/ΔT of 0.6.
A base paper for pressure-sensitive copying paper having a Clark stiffness of 13° and 8 cm was obtained.

Pressure-sensitive copying paper was prepared in the same manner as in Example 1, except that this base paper was used, and a performance comparison test was conducted, and the results are listed in the table.

Comparative Example 1 LBKP9 each beaten to a freeness of 400 cc
A base paper for pressure-sensitive copying paper was obtained in the same manner as in Example 1 except that a pulp suspension consisting of 0 parts of NBKP and 10 parts of NBKP was used. The base paper had a ΔW/ΔT of 0°75 and a Clark stiffness of 10.8 cm.

Pressure-sensitive copying paper was prepared in the same manner as in Example 1, except that this base paper was used, and a performance comparison test was conducted, and the results are listed in the table.

Comparative Example 2 Regenerated pulp was obtained in the same manner as in Example 2, except that in the regenerated pulping process of Example 2, a mixer was used instead of the kneader, and the stirring treatment was carried out at a pulp concentration of 10%. This recycled pulp has a whiteness of 70% and a freeness of 500 cc.
Met. This recycled pulp was made into paper in the same manner as in Example 2 to obtain a base paper for pressure-sensitive copying paper. This base paper had a ΔW/ΔT of 0.72 and a Clark stiffness of 9.4 cm.

Pressure-sensitive copying paper was prepared in the same manner as in Example 1, except that this base paper was used, and a performance comparison test was conducted, and the results are listed in the table.

Comparative Example 3 In Example 2, talc was added so that the ash content was 15%, and the amount of rosin size added was changed from 1.6% to 0.01%.
A base paper for pressure-sensitive copying paper was obtained by making paper in the same manner as in the example except that . This base paper had a ΔW/ΔT of 0.35 and a Clark stiffness of 8.9 cm.

Pressure-sensitive copying paper was prepared in the same manner as in Example 1, except that this base paper was used, and a performance comparison test was conducted, and the results are listed in the table.

The heat shrinkage rate (%) is 31.6 cm x 3.1.6 c
Measure the length of a sample piece of m after conditioning it at 20°C and 165% RH for 2 hours, heat it by placing it in an oven at 110°C for 3 minutes, and then conditioning it again at 20°C and 165%RH for 2 hours and measure its length. I measured and calculated.

[NIP suitability test] Pressure-sensitive copying paper with a paper width of 394 mm, perforations and marginal punches was printed using a form printing machine (NIPC Hitachi Koki H-6275 model) to check its suitability for folding with a stamper and the occurrence of later skew. We tested the presence or absence of

"Evaluation criteria" ○: No oblique bending and good foldability.

×: Tilt occurs, folding with a stanker is poor, and running performance is poor.

[Color development test]

The inner paper and the lower paper are stacked so that the capsule-coated side of the inner paper and the developer-coated side of the lower paper face each other, and the weight is 600 kg.
The density of the color image obtained by applying a load of /cm2 was measured using a Macbeth densitometer (model RD-914, Filter Visual).
It was measured with

[Color stain test]

The inner paper and the lower paper are stacked so that the capsule-coated side of the inner paper and the developer-coated side of the lower paper face each other, and the weight is 4 kg/c.
The degree of colored staining on the surface coated with the color developer was determined by rubbing it together five times under a load of m2.

"Evaluation criteria" ◎: Hardly dirty.

○: Slightly dirty.

×: Significantly dirty.

Table 1: "Effects" As is clear from the results in Table 1, the pressure-sensitive copying paper of the present invention was a pressure-sensitive copying paper with excellent NIP suitability, less color development stains, and excellent color development ability.

Claims (4)

[Claims] (1) In pressure-sensitive copying paper that utilizes a color-forming reaction between an electron-donating color former and an electron-accepting color developer, the base paper has a heat shrinkage rate ΔT in the papermaking direction and a heat shrinkage rate ΔW in the width direction of 0. 40≦
A pressure-sensitive copying paper characterized by using a base paper having a relationship of ΔW/ΔT≦0.70. (2) Clark stiffness of base paper (JIS P-8143, A
2. The pressure-sensitive copying paper according to claim 1, wherein the pressure-sensitive copying paper has a diameter of 10 cm or more. (3) The pressure-sensitive copying paper according to claim (1) or (2), wherein the base paper contains recycled pulp made from waste paper. (4) The recycled pulp according to claim (3), wherein the recycled pulp is a recycled pulp obtained by a deinking process including a mechanical stirring step of applying compressive force to the waste paper in the presence of a surfactant-based deinking agent. Pressure copy paper.