JPH03284980A - Pressure-sensitive copy paper - Google Patents

Abstract

PURPOSE:To effectively improve a strike through phenomenon, the shortage of printing ink and developed color fog by using raw paper wherein regenerated pulp content is 10wt.% or more, the number of pinholes of 0.05mm<2> or more is 150 or less per 100cm<2> and regular reflection type surface smoothness under pressure of 20kg/cm<2> is 10% or more as a support. CONSTITUTION:Since the surface smoothness or paper strength of raw paper is lowered when regenerated pulp is compounded in an untreated state, it is desirable to treat the regenerated pulp by a beater and the Canadian Standard Freeness thereof is pref. lowered to about 30-150ml. In the surface smoothing treatment of the raw paper, a super calender, a gloss calender or a soft calender constituted of a metal roll and an elastic roll is used according to an ON- machine or OFF-machine system. A microcapsule-containing coating solution or a developer-containing coating solution is applied to the raw paper thus obtained to finish the raw paper as 'upper paper', 'lower paper', 'middle paper' or 'self-developing paper'.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to pressure-sensitive copying paper, which has particularly high opacity, no color fogging (staining) during printing, and printability without printing ink short-circuit. This paper relates to pressure-sensitive copying paper that has excellent properties.

``Prior art'' Pressure-sensitive copying paper (so-called carbonless paper) is made of electron-donating color formers (hereinafter referred to as color formers) such as crystal violet lactone and hendyl leucomethylene blue, activated clay,
Electron-accepting color developers (hereinafter referred to as color developers) such as hentonite, phenolic resins, polyvalent metal salts of aromatic carboxylic acids, etc.
It utilizes the color-forming reactivity of A colored image can be obtained on the lower paper by placing a lower paper coated on the surface of the paper, with each coated surface facing each other, and printing on the surface of the upper paper under pressure using a typewriter or the like. If you wish to make even more copies, insert the required number of inner sheets coated with the color developer on the front side of the base paper and microcapsules on the back side between the upper and lower sheets. You can obtain one copy. Also, so-called self-coloring paper in which the above-mentioned microcapsules and color developer are formed as a laminated or mixed layer on the same surface of a base paper is also well known as a form of pressure-sensitive copying paper.

In recent years, the demand for pressure-sensitive copying paper has been increasing significantly as its uses have expanded, with a wide variety of uses, such as general slips, contract documents, and computer paper.

When used for slips, contract documents, etc., various types of printing may be performed on both sides of the top, middle, and bottom sheets of pressure-sensitive copy paper depending on the use and purpose. Incidentally, each of the sheets of pressure-sensitive copying paper, that is, the top sheet, middle sheet, and bottom sheet, is generally made of a thin base paper weighing 30 to 50 g/board in order to provide better copyability. However, when such thin base paper is used, a problem of so-called strike-through occurs in which the printed images on both sides are visible through each other. For example, when pressure-sensitive copying paper is used for policy documents such as insurance contracts, it may be printed on one side with low-density ink such as indigo, gray, or sepia. In such a case, if ink with a high color density is printed on the opposite side, the print image with a high color density will appear on the opposite side as a strike-through phenomenon, making it difficult to read the print or printed image with a low color density. Furthermore, if printed images are made on both sides using ink with a high color density, the printed images of the opposite sides appear on each side due to a strike-through phenomenon, making it difficult to read the layers. Furthermore, if the paper has many pinholes, the printing ink bleeds to the back side (printing ink short), resulting in poor printability such as ink show-through. Furthermore, after printing on the top paper and the middle paper, a copy set is made so that the color developer-containing microcapsule layer faces the developer surface of the middle paper or the bottom paper, and the sets are stacked and stored. This also causes the problem of color development fog occurring on the developer surface.

On the other hand, in addition to resource conservation, the paper contained in municipal waste has received particular attention in recent years. Contrary to what was said to be a "paperless" society with the progress of office automation (OA), a large amount of information paper called OA paper is being discarded from offices and factories, and newspaper insert advertisements are being discarded. The consumption of coated paper for printing is rapidly increasing due to the increasing visualization, colorization, and luxury of magazines, magazines, and advertisements, and the disposal of this rapidly increasing amount of paper waste is currently becoming a major social problem. ing.

Japan's waste paper recovery rate is approximately 50%, which is higher than other developed countries.
For example, 90% of used newspapers are recovered. Approximately 40% of the raw material for newspaper production is made up of waste paper pulp. However, when waste paper pulp is used as a raw material for so-called information paper such as pressure-sensitive copying paper and heat-sensitive recording paper, quality problems may occur, so it is not fully utilized as a raw material for these materials.

The use of waste paper for pressure-sensitive copying paper has disadvantages such as a decrease in the smoothness of the copying paper surface and worsening of color fog, so that it has not yet been put to practical use.

``Problems to be Solved by the Invention'' As mentioned above, the present invention addresses the problem of strike-through, which is a problem when pressure-sensitive copying paper is used for printing, and bleeding of printing ink to the back side (printing ink short). ) and a pressure-sensitive copying paper with excellent printability that has very effectively improved the problems of color fog during printing.

"Means for Solving the Problems" The present invention provides a pressure-sensitive copying paper having a coating layer on a support that utilizes a color-forming reaction between an electron-donating color former and an electron-accepting color developer. , the total pulp composition contains 10% by weight or more of recycled pulp made from waste paper, and
0.05■12 or more pinholes are 15 per 100d
It is characterized by using a base paper in which the number of particles is 0 or less and the specular reflection type smoothness of the surface is 10% or more under a pressurizing condition of 20 kg/C11l.

"Function" As a result of intensive research into improving the above-mentioned drawbacks, the present inventors have found that these drawbacks are largely caused by the characteristics of the base paper that makes up pressure-sensitive copying paper, especially the characteristics of the pulp that makes up the base paper. I discovered that.

In other words, chemical pulp has traditionally been used as the pulp constituting base paper, but satisfactory results have not been obtained even after various adjustments to the beating conditions and paper-making conditions. A certain amount of recycled pulp (hereinafter referred to as recycled pulp) is blended to control the number of pinholes, which are minute defects in the base paper, and to adjust the smoothness of the base paper surface to a specific level as measured by a special smoothness meter. When adjusted to this value, the strike-through phenomenon of pressure-sensitive copying paper using this base paper is effectively improved, and color capri during printing and short-circuit phenomena caused by printing ink on the back side are also improved. Heading: The present invention has been completed.

In the pressure-sensitive copying paper of the present invention, a base paper containing 10% by weight or more of recycled pulp in the total pulp composition is used as a support. In comparison, the compressive elastic modulus of the base paper is lower and the pressing pressure is buffered, so it is presumed that color fog during printing is effectively improved. Furthermore, due to its history, recycled pulp has a higher light scattering coefficient than chemical pulp, which increases the opacity of the base paper and improves strike-through. Incidentally, if the amount of recycled pulp used is less than 10% by weight, sufficient improvement effects cannot be expected.

Specific examples of raw materials for recycled pulp include, for example, top white, ruled white, cream top white, card, special white, medium white, imitation, colored clay, Kent, white art, special top cut, special top cut, newspapers, and magazines. (Used Paper Standard Quality Specification Table: @Compiled by Waste Paper Recycling Promotion Center). Regenerated 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. In the disintegration process, low concentration pulper, high concentration pulper, etc. are used, screens, cleaners, etc. are used in the rough selection process and fine selection process, and in the deinking process, flotation method, water washing method, compromise method, etc. selected based on quality.

Note that if the obtained recycled pulp is blended without being treated, there is a risk that the smoothness of the surface of the base paper and the paper strength of the base paper will decrease. Therefore, it is preferable to treat the untreated recycled pulp with a beating machine in the pre-process of the paper machine, and it is preferable to reduce the Canadian Standard freeness of the untreated recycled pulp in the range of about 30 to 150 degrees Fahrenheit. 30J.

If the beating temperature is less than 1,507, it is difficult to obtain a sufficient smoothness improvement effect, whereas if the beating is more than 1507, the compressive elastic modulus of the obtained base paper becomes high, and the desired effect of the present invention becomes small. There is a risk that it will happen.

As the refining machine, a conical refiner, a single disc refiner, a double disc refiner, etc. are used, but in consideration of power, it is more preferable to use a double disc refiner.

In addition, recycled paper pulp is more likely to have pinholes, which are minute defects (holes), in the base paper than chemical pulp. The reason for this is presumed to be that the surfactant used as a deinking agent remains in the recycled pulp of used paper, resulting in increased foaming and poor yield of keratinized fibers. When printing on one side, these pinholes cause the ink to bleed to the opposite side, impairing the printing effect, so the number of pinholes must be adjusted. That is, it is important that the number of pinholes of 0.05 mm or more in the base paper is 150 or less per 100.

The number of pinholes can be controlled by the capacity of the dust remover and deaerator before the inlet, pulp beating conditions, papermaking conditions such as foil arrangement, size press conditions, and internal additives such as retention improvers and antifoaming agents. This is done by appropriately selecting the type and amount of addition.

In the pressure-sensitive copying paper of the present invention, as described above, recycled pulp is
This paper uses a base paper containing % by weight or more, but the surface of the base paper is further tested with a specular reflection type smoothness meter (measurement pressure: 20k).
It is necessary to process so that the measured value in g/cm2) is 10% or more, more preferably 14% or more.

The specular reflection type smoothness meter referred to here is a device that measures the smoothness of a glass surface by pressing paper against the glass surface under constant pressure conditions, and is a general air leak type smoothness measuring device. It is not affected by the air permeability of the paper, unlike the specular reflection type smoothness meter (measurement pressure; It has become clear that the desired effect of the present invention can be determined very appropriately by the measured value at 20 kg/cI112).

Incidentally, the regular reflection type smoothness of the base paper surface (measurement pressure: 20 kg/
cI! If +2) is less than 10%, color fog during printing cannot be effectively improved even if the base paper contains 10% by weight or more of recycled pulp.

For smoothing the surface of base paper, machine calenders consisting only of metal rolls installed at the rear of Fourdrinier or circular wire paper machines can also be used, but supercalendar gloss calenders consisting of metal rolls and elastic rolls can also be used. It is effective to use a soft calendar, etc., on-machine or off-machine.

As the metal roll, for example, a chilled roll, an alloy chilled roll, a steel roll, or a metal roll whose surface is plated with hard chrome, etc. are selected and used as appropriate.As for the elastic roll, for example, natural rubber, styrene rubber, nitrile rubber, chloroprene, etc. are used. Rubber, chlorosulfonated ethylene rubber, butyl rubber, polysulfide rubber, silicone rubber, fluorine rubber, urethane rubber, aromatic polyamide resin, polyimide resin, polyether resin, polyester resin, polycarbonate resin, etc., various plastic resins, cotton, etc.
An elastic roll made of paper, wool, Tetoron, nylon, or a mixture thereof is appropriately selected and used.

Note that, in terms of efficiency, on-machine smoothing treatment is preferable, and in this case, a calender composed of elastic rolls having a Shore D hardness of 42 to 98 degrees (ASTM standard, D-2240) is particularly preferably used. Among these, elastic rolls made of urethane rubber, aromatic polyamide resin, a mixture of paper and wool, a mixture of wool and Tetron, a mixture of wool and nylon, a mixture of paper, wool and Tetron, a mixture of paper, wool and nylon, etc. are preferred. In particular, elastic rolls made of urethane rubber and aromatic polyamide resin are most preferably used because they are easy to handle, have a long roll life, and efficiently exhibit the desired effects of the present invention.

Elastic rolls such as those mentioned above are softer than normal elastic rolls (and tend to generate heat even under stable operating conditions, and this tendency is particularly noticeable in elastic rolls made of urethane rubber.The heat generation phenomenon causes physical properties of the elastic body. The elastic properties may become unstable, and in extreme cases, the elastic body itself may be damaged by melting due to the accumulated heat. Therefore, it is a preferable embodiment to introduce a refrigerant inside the roll for cooling. Various measures are taken as appropriate, such as cooling from the base, changing the roll diameter, and changing the thickness of the elastic body.

On-machine super calenders and on-machine soft calenders, which are composed of metal rolls and elastic rolls, are published in the August 1988 issue of Gio Pulp Technology Times (page 31) and in 1988.
It is introduced in the May issue (page 10), etc. Further, processing conditions are appropriately adjusted depending on the number of nips, nip linear pressure, machine speed, etc.

It is also possible to smooth the base paper surface by using a Yankee dryer whose dryer surface has been mirror-treated with hard chrome plating, etc. as the paper machine dryer, but in any case, regular reflection type smoothing of the base paper surface is possible. It is necessary to make the measured value at 10% or higher (measurement pressure, 20 kg/α2).

The base paper thus obtained is coated with a microcapsule-containing coating liquid or a color developer-containing coating liquid in accordance with a conventional method to form "upper paper".
It can be finished as "lower paper", "middle paper", "self-coloring paper", etc., but there are no particular limitations on the method of applying the coating liquid, such as air knife coater, roll coater, blade coater, ronto coater, curtain coater, etc. A coating liquid having a dry weight of about 2 to 10 g/m'' is applied and dried using a suitable coating device.

Microcapsule-containing coating liquids generally include triarylmethane lactones, spiropyrans, fluorans,
Basic dyes such as diphenylmethanes and azines are combined with 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. It is prepared by dissolving it in a solvent consisting of the following, containing it in microcapsules by various capsule manufacturing methods such as coacervation method, interfacial polymerization method, and 1n-situ method, and dispersing it in a binder.

Coating liquids containing color developers 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, and benzoic acid. , salicylic acid, 3-isopropylsalicylic acid, 3-phenylsalicylic acid, 3-cyclohexylsalicylic acid, 3-methyl-5(α-methylbenzyl)salicylic acid, 3-methyl-5(α,α-dimethylbenzyl)salicylic acid, 3,5-dimethylsalicylic acid 5ec-butylsalicylic acid,
3,5-di-tert-butylsalicylic acid, 3,5-di-tert-butyl-6-methylsalicylic acid, 3-te
rt-butyl-5-phenylsalicylic acid, 3.5-diter t-amylsalicylic acid, 3.5-dicyclohexylsalicylic acid, 3-cyclohexyl-5-(αmethylbenzyl)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-dimethylbenzyl)salicylic acid, 3-(α-methylbenzyl) -Salicylic acid, 3-(α-methylbenzyl)5-methylsalicylic acid, 3-(α-methylbenzyl)5-phenylsalicylic acid, 3-(α-p-)′)ruethyl)-5-methylsalicylic acid, 3,5 -di(α-p-tolylethyl)salicylic acid, 3-(α,α-dimethylbenzyl)-5-methylsalicylic acid, 3-(α,α-dimethylbenzyl)-6-
Methyl salicylic acid, 3I5-di(α,α-dimethylbenzyl)salicylic acid, 3,5-di(α-methylbenzyl)
Salicylic acid, 3-(α-methylbenzyl)-5-(α,
α-dimethylhensyl)salicylic acid, 3-(α-methylbenzyl)5-bromosalicylic acid, 3-(α-methylbenzyl)-4-methylsalicylic acid, 3-(α~methylbenzyl)6-methylsalicylic 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, benzylated styrenated salicylic acid, 2-hydroxy-3-(α,α-dimethylbenzyl)-1-naphthoic acid, 3-hydroxy-2-naphthoic acid, 3-hydroxy- Organic color developers such as aromatic carboxylic acids such as 7-(α,α-dimethylhensyl)-2-naphthoic acid, phenolic resins such as p-phenylphenol-formalin resin, and p-butylphenolacetylene resin; Organic color developer such as zinc, magnesium, aluminum,
It is prepared by dispersing various color developers, such as salts with polyvalent metals such as calcium, titanium, manganese, tin, and nickel, in a binder.

Examples of binders include starches, cellulose, proteins, gum arabic, polyvinyl alcohol,
Styrene-maleic anhydride H copolymer salts, styrene-butadiene copolymer emulsions, acetic acid bee-maleic anhydride copolymer salts, polyacrylic acid salts, 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 Japanese Patent Application No. 3,418,250, Japanese Patent No. 3,924,027, Japanese Patent No. 4,010,038, etc., there are various forms of the present invention. This can be applied to pressure copy paper.

``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 (1) Preparation of base paper Freeness 24o77I10 regenerated bulb made from newspaper was refined in a double disc refiner to obtain a freeness of 100-. 10 parts of this recycled pulp, 70 parts of LBKP beaten to a freeness of 50/pJ, and N
Talc was added to the pulp suspension obtained by blending 20 parts of BKP 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 fourdrinier cylinder dryer paper machine, and an aqueous solution of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) was added to the dry weight. It is size pressed to 1.5 g/g and processed with a machine calendar to have a basis weight of 40 g/ld and 45 pinholes of 0.05 mm or more.
pieces/100 all, specular reflection type smoothness (pressure condition 20
kg/e11! ) was obtained as a base paper for pressure-sensitive copying paper of 11%.

■ 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 diisopropylnaphthalene (trade name: Ni-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 was continued. After cooling, a milky white capsule dispersion was obtained.

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) to the base paper with a dry weight of 48/n? A top sheet for pressure-sensitive copying paper was prepared by applying and drying the mixture to give the following properties.

■ Preparation of 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 toluene.
The mixture was mixed and dissolved at ℃ 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 100 J, and a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) was heated at 3000 per minute. The above toluene solution was added thereto with rotational stirring.

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 100 J hard glass three-neck flask 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 liquid 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. 0SG-8G) at a rate of 2 kg per minute to prepare a color developer dispersion having an average particle size of 0.97 μm. .

[Preparation of 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, as a binder, 100 parts of a 10% polyvinyl alcohol aqueous solution and 50% carboxy-modified S
BR Latex (SN-307+ Resident Nogata.

A developer coating solution was prepared by mixing and dispersing 20 parts (manufactured by Co., Ltd.) and 200 parts of water.

[Manufacture of inner paper]

Apply the above color developer coating solution to one side of the base paper with a dry weight of 6 g.
After coating and drying, the capsule coating liquid was coated and dried to a dry weight of 4 g/m on the opposite side to the developer-coated side to prepare an inner sheet for pressure-sensitive copying paper.

A performance comparison test was conducted using the top paper and inner paper thus obtained, and the results are listed in the table.

Example 2 Freeness 40077L/17) recycled pulp made from imitation was beaten in a double disc refiner,
The freeness was set at 4. 10 parts of this regenerated valve, 70 parts of LBXP beaten to freeness 5007, and N
Talc was added to the pulp suspension obtained by blending 20 parts of BKP so that the paper ash content was 6%, and as a sizing agent, the rosin size was adjusted to 1.4% based on the bone dry pulp.
% added.

After adjusting the pH of this valve slurry to 4.6 with a sulfuric acid band, paper was made using a fourdrinier cylinder dryer paper machine, and an aqueous solution of oxidized starch (trade name: Ace A, manufactured by Oji Cornstarch Co., Ltd.) was added to the dry weight. It is size pressed to 1.5 g/rd and processed with an on-machine calendar consisting of a metal roll and an elastic roll (Shore D hardness 91 degrees) to give a basis weight of 40 g/d and a pinhole count of 72/100.
cm2, specular reflection type smoothness (pressure condition 20 kg /
A base paper for pressure-sensitive copying paper having cIa) of 16% was obtained.

A 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 shown in the table.

Example 3 Freeness 200 recycled pulp made from newspaper was refined in a double disc refiner to give a freeness of 100-. 50 parts of this recycled pulp and 500 parts of freeness
Talc was added to the pulp suspension obtained by blending 50 parts of beaten NBKP to the pulp suspension 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 an aqueous solution of oxidized starch (trade name: Ace A, manufactured by Tamago Cornstarch Co., Ltd.) was added to a dry weight of 1. It was size pressed to 5 g/rrr and processed with an on-machine calendar consisting of a metal roll and an elastic roll (Shore D hardness 91 degrees) to a size of 140 g/d and 137 pinholes/
100cn! , specular reflection type smoothness (pressure condition 20kg/
A base paper for pressure-sensitive copying paper having cj) of 18% was obtained.

A 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 shown in the table.

Example 4 Regenerated pulp with a freeness of 420-, which was made from Jojiro as a raw material, was refined in a double disc refiner to obtain a freeness of 300-doro. 90 parts of this recycled pulp and 500 parts of freeness/
? Talc was added to the pulp suspension obtained by blending the beaten NBKPIO part with I/I so that the paper ash content was 6%, and rosin size was added as a sizing agent to 1.4% based on the bone dry pulp. Added.

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 an aqueous solution of oxidized starch (trade name: Ace A, manufactured by Tamago Cornstarch Co., Ltd.) was dried by gravity. Month.

Size pressed to 5 g/rd, processed with an on-machine calendar consisting of a metal roll and an elastic roll (Shore D hardness 87 degrees) to give a basis weight of 40 g/d, number of pinholes 113/100 cflf, Specular reflection type smoothness (
A base paper for pressure-sensitive copying paper with a pressure condition of 20 kg/cm2) of 16% was obtained.

A 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 shown in the table.

Example 5 Recycled pulp made from newspaper and having a freeness of 200 was refined using a double disc refiner to obtain a freeness of 1504. 10 parts of this recycled pulp, 70 parts of LBKP beaten to a freeness of 500 and 20 parts of NBKP.
Heavy calcium carbonate (trade name: Softon 1200, manufactured by Bihoku Funka Co., Ltd.) is added to the pulp suspension obtained by blending
was added so that the paper ash content was 6%, and 0.5% of sulfuric acid hand was added to the bone-dry pulp, and cationic starch (trade name: CATO-F, manufactured by Tamago National Co., Ltd.) was added to the bone-dry pulp. After adding 0.5% of alkyl ketene dimer (trade name: SPK 90, manufactured by Arayo Kagaku Co., Ltd.) as a neutral sizing agent to the bone dry pulp, a fourdrinier multi-cylinder cylinder dryer was added. Paper is made using a paper machine, and oxidized starch (product name: Ace A) is used.

An aqueous solution of Egg Corn Starch Co., Ltd.) with a dry weight of 1.5
g/tri, and then processed with an on-machine calender consisting of a metal roll and an elastic roll (Shore D hardness 91 degrees) to give a basis weight of 40 g/d, number of pinholes 40/100 ad, positive A base paper for pressure-sensitive copying paper having a reflection type smoothness (pressure condition: 20 kg/an!) of 15% was obtained.

A 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 shown in the table.

Comparative Example 1 Freeness so o Jc beaten LBKP
A base paper for pressure-sensitive copying was obtained in the same manner as in Example 1 except that a pulp suspension consisting of 80 parts of NBKP and 20 parts of NBKP was used. The number of pinholes in this paper is 23/10
0-2 specular reflection type smoothness (pressure condition; 20kg/am”
) was 10%.

A 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 shown in the table.

Comparative Example 2 Freeness 2404 regeneration valve 90 made from newspaper
A base paper for pressure-sensitive copying paper was obtained in the same manner as in Example 1, except that a valve suspension obtained by blending a beaten NBKPIO part and a freeness part of 500- was used. The number of pinholes of this base paper was 210/100 ails, and the specular reflection type smoothness (pressure condition; 20 kg/cm) was 7%.

A 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 shown in the table.

Comparative Example 3 A freeness 240 do regenerated bulb made from newspaper was refined in a double disc refiner to obtain a freeness of 1004. In addition, Freeness 40, which is made from imitation,
The 0- regenerated bulb was refined with a double disc refiner to obtain a freeness of 250J. A base paper for pressure-sensitive copying paper was obtained in the same manner as in Example 1, except that a pulp suspension obtained by blending 30 parts of NBKP beaten in Freeness 5004 with 50 parts and 20 parts of each of the regenerated valves was used. The number of pinholes in this paper is 165/10
0 cm2, specular reflection type smoothness (pressure condition; 20 kg/a
m”) was 11%.

A 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 shown in the table.

Comparative Example 4 Freeness 240 )'/17) made from newspaper as raw material. Regenerated valve was refined with a double disc refiner and 200
The freeness was set at 4. A base paper for pressure-sensitive copying paper was obtained in the same manner as in Example 1, except that a pulp suspension obtained by blending 50 parts of this regenerated valve with 50 parts of NBKP beaten to a freeness of 500- was used. The number of pinholes in this base paper was 148/100 cj, and the specular reflection type smoothness (pressure conditions: 20 kg/an2) was 8%.

A 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 shown in the table.

"Evaluation" [Strike-through] For the upper paper and inner paper, offset printing and text printing were performed partially on the capsule-coated surface under the following conditions, and ruled lines and text were printed on the back surface. At this time, a visual evaluation was made to see how difficult it was to distinguish the printed images printed on both sides from the show-through τ of the printed image on the opposite side.

Printing machine: Business Form Printing Machine 178H (manufactured by Mei Seisakusho) Ink: Black ink with Champion F Gloss 857 manufactured by Dainippon Ink ■) "Evaluation Criteria" A: No show-through, easily distinguishable.

B: Slightly difficult to distinguish due to show-through.

C: Severe show-through and difficult to distinguish.

[Print color fog]

Using a business form printing machine 17BH (manufactured by Mei Seisakusho), printing was performed on the developer-coated surface of the inner paper using a wet offset printing method, and the paper was rolled up to a length of 300 m. 5. Winding after printing
After being left at 0° C. for 3 days, the state of dirt on the developer-coated surface at a distance of about 100 m from the winding core was visually determined.

"Evaluation criteria" A: Almost no stain (color development).

B: Very dirty (colored).

[Printing ink short]

On the capsule-coated surface of the upper paper, use R1 tester (manufactured by Mei Seisakusho) to ink the black ink with New Champion F Gloss 85/
(manufactured by Dainippon Ink) was printed in an amount of 0.5 cc, and a short circuit phenomenon due to bleeding of the printing ink to the back side was visually determined.

“Evaluation base t$J A: Extremely good.

B: Good.

C: Bad.

Table “Effects” As is clear from the results in the table, the pressure-sensitive copying paper of the present invention has
The pressure-sensitive copying paper had almost no show-through phenomenon due to strike-through, significantly improved color capri (smudge) after printing, and had excellent printability with almost no printing ink shorts.

Claims (1)

[Claims] In pressure-sensitive copying paper that has a coating layer on a support that utilizes a color-forming reaction between an electron-donating color former and an electron-accepting color developer, the support is a recycled paper made from waste paper in the entire pulp composition. Contains 10% by weight or more of pulp, and 0.05m
Pinholes of m^2 or more are 150 per 100cm^2
or less, and the specular reflection type smoothness of the surface is under pressure condition 2.
A pressure-sensitive copying paper characterized by using a base paper having a density of 10% or more at 0 kg/cm^2.