JP5900844B2 - Colored paper manufacturing method and colored paper - Google Patents

Description

The present invention relates to a colored paper manufacturing method and colored paper that can improve the efficiency of colorant fixation and improve production efficiency.

In the production of colored paper in which a paper is made by adding a colorant to a pulp raw material, there are a batch type and a continuous type as a coloring method. In the batch method, a certain amount of coloring agent is added to a chest or tank containing a certain amount of pulp slurry, and the coloring agent is fixed to the pulp. Since the fixing time of the dye can be taken long, the fixing rate is high and it is advantageous for the production of dark colored paper, but since the toning can be performed only for each batch, it is difficult to finely adjust the hue and adjust to the target hue It takes time to do. In a paper machine with a large production amount, a large amount of colored loss paper is generated. Therefore, this method is suitable for a paper machine with a relatively small production amount.

The continuous method is a method of continuously adding a colorant to the flowing pulp slurry. Colorants are continuously added to machine chests, seed boxes, fan pumps, etc. in the paper machine pre-process. Since the amount of the colorant added can be increased or decreased while looking at the paper to be produced, the hue can be finely adjusted, and the target hue can be adjusted in a shorter time than the batch type. For paper machines with a relatively large production volume, the continuous type is adopted. However, when producing dark colored paper with a large amount of colorant added, it takes a long time to meet the target hue.

Colored paper that has been produced to the desired hue can only be used when producing colored paper of the same or near hue, so if a large amount of paper is lost, a place to store it until the next papermaking It is necessary to cut, put in, and dissolve when used. Patent documents relating to the coloring method of paper include the following.

The colorant is continuously injected into the primary side of the screen for selecting the complete paper material sent to the paper machine so as to be fixed per unit time. (Problem) It is possible to facilitate the work of determining the concentration of the colorant relative to the paper material per unit volume, shortening the fixing time, eliminating the trouble of washing the color paper material remaining in the flow path. (Patent Document 1)

The dye is added directly at the front stage of the pulp adjustment process, and the basic dye is added in the seed box immediately before the paper machine. The color tone is adjusted by adjusting the amount of basic dye added. (Problem) To provide a method for dyeing a surface layer of a liner, which does not cause a problem of fading or color rendering, and can immediately respond to a change in product color tone. (Patent Document 2)

At least two or more types of basic dyes are added in at least two places in the process from mixing to supplying the raw material to the paper machine to adjust the color tone within a specific range. (Purpose) Make sure to adjust to the desired color tone. (Patent Document 3)

As described above, various proposals for specifying the colorant addition location and the colorant type have been made. This is because there is a reason that there is still no complete solution.
In the production of colored paper, if the same amount of colorant is added to the same pulp for each production, colored paper of the same hue should be obtained, but in reality it depends on various factors such as pulp quality and water quality. Since the fixing property of the colorant is changed, it is necessary to adjust the color to the target color every production. Since this operation is performed while continuously making paper and checking the hue, a lot of damaged paper is generated. Usually, even if an action for changing the addition rate of the colorant is taken in order to match the colors, a certain time is required until it appears as the hue of the paper.

If the place where the colorant is added is close to the paper machine such as a seed box or a fan pump, the time until the result of the action appears is shortened, but the fixing is insufficient and the colorant concentration in the system is stable. It takes time to do.
If the place where the colorant is added is away from the paper machine such as mixing or a machine tank, the fixing time is sufficient, but the time until the action result appears becomes longer.

Factors affecting the fixability of the colorant to the pulp include the type of pulp, the degree of pulp beating, the effect of chemicals such as yield improvers, the temperature of the water, pH, hardness, and the addition process (addition location). . Also, the hue may change depending on the state of the wire and blanket of the paper machine (dehydration and squeezing conditions).
With respect to the change in hue due to these factors, the human sense of hue is sharp, and the range of hues allowed when manufacturing colored paper is very small. Therefore, in the case of colored paper, it takes a longer time to match the color than ordinary white printing paper, etc., and the amount of spoiled paper tends to increase. In some cases, the hue changes during the production of colored paper. Waste paper may be generated.

There is the following patent document as a manufacturing method of colored paper that does not require consideration of the fixing property of the colorant.
A dye / pigment carrier in which a dye / pigment is supported on fine fibrillated cellulose is added to and mixed with a paper stock prepared using pulp for papermaking as a main material, and then the paper stock is made. (Purpose) To provide a method for producing a dyed paper which can fix a high level of dyes and pigments without requiring a complicated work requiring skill and does not deteriorate formation or light resistance due to the combined use of a large amount of dyeing assistant. (Patent Document 4)

Even in the case of colored paper with a large amount of dye addition or colored paper having a high blending ratio of waste paper pulp with non-uniform quality, even with techniques such as Patent Documents 1 to 3, until the desired hue is obtained for each production Need a lot of time. According to Patent Document 4, it is necessary to produce fine fibrillated cellulose for producing a dye / pigment carrier in addition to the production of ordinary pulp, which increases the production cost and is difficult to apply to mass production. Further, since the dye / pigment carrier is finely fibrillated cellulose, if the content is high, the papermaking property (water drainage) is deteriorated.

Japanese Examined Patent Publication No. 7-103516 JP 2002-88686 A JP 2005-15976 A JP 7-324300 A

The object of the present invention is intended to solve the above problems. That is, it is an object to provide a colored paper manufacturing method and a colored paper capable of improving the production efficiency because the colorant is well fixed and the time until the target hue is reached is short.

The inventors of the present invention are able to solve the above problems even in highly colored waste paper with a high content of used paper by specifying the colorant addition method and addition location different from conventional ones, and further specifying the type of colorant. The headline and the present invention have been completed.

The colored paper manufacturing method and colored paper of the present invention have the following configuration.
(1) A method for producing a colored paper, in which a colorant is continuously added to a pulp raw material to make a paper, wherein at least one colorant is added to white water of a paper machine.
(2) The method for producing colored paper according to (1), wherein the colorant added to the white water is a basic dye and / or a cationic direct dye.
(3) The method for producing colored paper according to (1) or (2), wherein the pulp raw material contains 50% or more of waste paper pulp.
(4) A colored paper obtained by the production method according to any one of (1) to (3), wherein L according to the Lab color system measured in accordance with JISP8150 is 80 or less. Colored paper.

According to the present invention, even when dark colored paper is produced on a paper machine with a large production amount, it is possible to adjust to the target hue in a short time, and the colored paper can reduce the amount of colored spoiled paper generated. And a colored paper can be provided. Further, since the fixing of the colorant to the pulp is improved, it is possible to provide a colored paper manufacturing method and a colored paper that can reduce the basic unit of the colorant and reduce the drainage load. Furthermore, there is no need to add production facilities.

Flow chart showing the method for producing colored paper of the present invention

Embodiments of the present invention will be described below. In the method for producing colored paper of the present invention, a paper machine comprising the steps of a wire part, a press part, a dryer part, and a reel part is used.

In the method for producing colored paper according to the present invention, kraft pulp, waste paper pulp, mechanical pulp and the like can be used as raw material pulp. As the kraft pulp, softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP), and the like can be used. In addition, as waste paper pulp, deinked pulp (DIP) such as newspaper waste paper deinked pulp and high-quality waste paper deinked pulp can be used. As the mechanical pulp, stone ground pulp (SGP), pressurized stone ground pulp (PGP), refiner ground pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), or the like can be used.

When the colored paper which is the object of the colored paper manufacturing method of the present invention contains 50% or more of waste paper pulp as a pulp raw material, the effect of the present invention is further enhanced. A high content of waste paper pulp is desirable in terms of promoting recycling, but the upper limit is determined by the quality of the colored paper such as hue, appearance, and required strength.

In the method for producing colored paper of the present invention, a filler may be added. The type of filler to be used is not particularly limited, and fillers generally used for paper, such as inorganic fillers such as calcium carbonate, talc, clay, titanium dioxide and white carbon, and plastic pigments, etc., as needed to improve opacity, etc. Can be used.

The hue of the colored paper that is the object of the method for producing the colored paper of the present invention can be arbitrarily set, but a dark color such that L according to the Lab color system measured in accordance with JISP8150 is 80 or less, and further 75 or less. In the case of the colored paper, the effect of the present invention is even greater. Such a low L colored paper has a large amount of colorant added.

A sulfate band, a sizing agent, a paper strength enhancer, a yield improver, a drainage improver, and the like can be added to the raw material pulp. As the sizing agent, a sizing agent such as rosin sizing agent, alkyl ketene dimer, alkenyl succinic anhydride can be used. As the paper strength enhancer, cationized starch, polyacrylamide resin and the like can be used. In addition, additives such as a slime control agent, a pitch control agent, and an antifoaming agent can be used.

Next, the coloring method in the manufacturing method of the colored paper of this invention is demonstrated.
Conventionally, in the continuous dyeing, the colorant is added to the raw material of the main line such as a machine tank, a seed box, a fan pump, etc. in the pre-process of the paper machine, based on the idea of fixing the colorant to the pulp.
In the present invention, the basic idea is to add a colorant to the white water of a paper machine that is not a raw material of the main line, and in this way, it becomes possible to match the target hue in a short time compared to the prior art, and coloring It has been found that the amount of waste paper generated can be reduced.
As chemicals added to white water, there are slime control agents and antifoaming agents, but these are auxiliary chemicals that do not need to be fixed to the raw material, and are added to white water. It is a concept that has never been before to add a colorant, which is a chemical that needs to be fixed to a raw material, to white water.

White water is a pulp suspension containing fine fibers and fillers that are drained when the stock is dewatered by the wire part of the paper machine. The prepared stock is sent to the paper machine at a concentration of 2.5-3.0%. This stock is diluted to 0.4 to 1.0% through the seed box on the suction side of the fan pump, and supplied from the head box to the wire part. In the wire part, a large amount of water is discharged through the wire, and the concentration of the wet paper becomes about 20%. This discharged water is about ½ of the concentration of the head box and contains fine fibers and fillers. This type of pulp suspension is generally called white water. White water from the wire part is used to dilute the high concentration stock described above. The concentration of white water varies depending on the pulp composition, filler addition rate, paper making speed, basis weight, wire part dewatering characteristics, and the like. In general, the concentration of white water is high when the ratio of waste paper pulp is high or when the addition rate of filler is high.

In the case of making newsprint, the ratio of the stock from the seed box to the stock from the white water out of the stock supplied to the inlet is about 20:80 in terms of flow rate, and about the amount of dry pulp. 70 to 30. (See Paper and Pulp Technology Association, Paper and Pulp Production Technology Series (6) “Paper making” on page 4)
Therefore, it can be seen that the ratio of the amount of pulp coming from white water is as high as about 30% in the absolute dry pulp amount of the stock supplied to the inlet.
In recent years, the proportion of fine fibers contained in waste paper has increased due to an increase in the ratio of recycled paper and the number of recycling, and more fine fibers are discharged into white water without riding on wires. It is thought that the ratio of the stock contained in white water out of the supplied stock is increasing. Under such circumstances, the colored paper manufacturing method of the present invention is advantageous.

At the start of papermaking, calculate the amount of stock in the whitewater silo based on the volume of whitewater silo that stocks whitewater and the concentration of whitewater, and add the colorant necessary to color the target hue. The concentration of the colorant in the system can be stabilized quickly.

Although the reason why the time for adjusting to the target hue can be shortened by the colored paper manufacturing method of the present invention is not clear, the following reasons (1) to (3) are conceivable.
(1) The colorant concentration in the papermaking system becomes constant quickly.
By adding the colorant directly to the white water with a large amount of circulation, the colorant concentration in the papermaking system is quickly and constant, and the hue of the colored paper to be produced is stabilized quickly.
(2) The fixing ratio of the colorant to the fine fiber is high.
When the same amount of colorant is added to the high freeness pulp and the low freeness pulp, the color density of the low freeness pulp is higher than that of the high freeness pulp. In general, when making colored paper, comparing the felt surface of the paper with the wire surface, the color density of the felt surface where many fine fibers remain is high. The reason for this is considered to be that fine fibers have a larger surface area and higher colorant fixing rate per unit weight of pulp than long fibers. Therefore, it is considered that the fixing ratio of the total colorant can be increased by preferentially dyeing fine fibers contained in white water.
(3) The fixing time of the coloring agent can be taken with the white water silo.
White water silos have a large capacity because the concentration of the stock needs to be stabilized, and because the stock has a residence time, it is possible to take a long time for the colorant to come into contact with the pulp. Becomes higher.

The raw material of the main line is diluted with white water and supplied to the paper machine, but since white water contains a lot of fine fibers, the color of the white water in the white water silo is only colored to some extent, and the hue of the paper becomes stable. It is thought to come. In the case of a dark colored paper with a high colorant addition rate in the conventional manufacturing method, the time until the white water of the white water silo is colored becomes longer, so the time until the hue of the paper becomes stable becomes longer. Therefore, it is considered that the hue of the paper is quickly stabilized if a colorant is added to white water containing a large amount of fine fibers.

Even if the colorant is added only to the white water and the colorant is not added to the raw material of the main line, the resulting paper has no uneven coloring, and a colored paper having a uniform hue can be obtained. The reason for this is considered to be that the fine fibers contained in the white water are so small that they cannot be visually recognized.

Examples of the colorant that can be used include basic dyes, dyes such as acid dyes, anionic direct dyes, and cationic direct dyes, and colored pigments such as inorganic pigments and organic pigments. Depending on the type of dye, there are dyes that require fixing time for pulp fibers and those that fix in a short time. When the dye is added in the raw material chest, the contact time with the pulp fiber is long, and the influence on the colorability is small. When added in the middle of the process, since the contact time is short, dyes that require a long fixing time tend to cause a decrease in the density of the colored paper, and those that fix in a short time may have uneven fixing and uneven color. Since the dye has little affinity for the filler, when the filler is porous, the dye is fixed in such a way that the void is filled with the dye.

Pigments are not used to color pulp fibers, but are used to color paper with its own colors. In addition to poor fixing, many pigments are more expensive than dyes, and light resistance is important. Used for colored paper.

As the colorant added to the white water in the present invention, it is desirable to use a basic dye or a cationic direct dye having a short fixing time to the pulp fiber. Basic dyes are well fixed to mechanical pulp but have poor light resistance. Cationic direct dyes have good light resistance but are expensive, so it is preferable to use them properly as necessary.

Even when such a dye having a short fixing time is used, it is added to white water having a low paper concentration, so there is little concern about the occurrence of uneven color as described above. Addition to the line is desirable because the dye is immediately diluted and dispersed to prevent color unevenness. The coloring agent is basically added to the white water, but may be added to the raw material of the main line such as a machine tank, a seed box, a fan pump or the like in the pre-process of the paper machine. In this case, it is desirable to add a dye that requires a long fixing time to the pulp fiber (many relatively inexpensive ones) in a process upstream of the machine tank because the fixing time can be secured.

A surface treatment agent containing a paper strength enhancer may be applied to the colored paper of the present invention for the purpose of improving the surface strength. The coating amount for obtaining the effect of the paper strength enhancer is about 0.2 to 1.5 g / m ^{2 on} one side, and usually the same coating amount is applied to both sides.

As a device for applying the surface treatment agent, a commonly used roll coater such as a two-roll size press coater or a gate roll coater, a blade coater, or a spray coater can be used.

As the paper strength enhancer to be applied, oxidized starch, cationized starch, polyacrylamide, polyvinyl alcohol, carboxymethyl cellulose, styrene maleic acid copolymer, styrene acrylic acid copolymer and the like can be used. In addition to the paper strength enhancer, chemicals such as surface sizing agents, lubricants, and anti-slip agents can be mixed and applied to the surface treatment agent.

In the method for producing colored paper of the present invention, the paper can be smoothed by a calender after drying with a dryer. As such a calendar device, a commonly used calendar device such as a chilled calendar, a soft calendar, or a gloss calendar can be used. The number of nips, nip pressure, roll temperature, roll material, roll hardness, etc. are set according to the target smoothness. The basis weight, thickness, smoothness, etc. of the colored paper of the present invention can be set according to the application.

It is desirable to install an on-line color sensor in the paper machine and continuously increase or decrease the amount of dye added by measuring the hue of the paper. By doing in this way, fine adjustment of a hue becomes easy and the change of the hue of the colored paper manufactured can be suppressed.

Next, the manufacturing method of the colored paper and the colored paper of the present invention will be specifically described by way of examples.
FIG. 1 is a flowchart showing a method for producing colored paper of the present application. Reference numeral 1 in the figure indicates a seed box, and the raw material of the main line is supplied to the seed box 1, diluted with white water stored in the white water silo 2, sent to the head box 3, and the papermaking wire 4 from the head box. Jetted up. White water that has passed through the wire is collected in the white water silo 2.

Machine chest of pulp, cationized starch 0.3% by mass and sulfuric acid band 3% (solid) to pulp dispersion liquid consisting of 90 parts by mass of deinked waste paper (230 ml CSF) and 10 parts by mass of thermomechanical pulp (110 ml CSF) 200 ppm of a coagulant (manufactured by Hymo Co., Ltd., trade name: Hymo Lock FR740) was added to the fan pump delivery side. As a colorant, yellow dye (manufactured by Nippon Chemical Industry Co., Ltd., trade name: basic yellow MGL, basic dye) 3000 ppm and green dye (manufactured by BASF Japan Ltd., trade name: Basazol Green 14L, basic dye) 75 ppm Continuously added to wire white water. Use a gate roll coater with the same coating amount on the front and back surfaces of oxidized starch (made by Oji Cornstarch Co., Ltd., trade name: Oji Ace A) as the surface treatment agent so that the coating amount is 0.80 g / m ² per side. Then, a colored paper was made at a basis weight of 49.0 g / m ² , a water content of 7.5%, and a paper making speed of 600 m / min. The target hue of the colored paper is L = 75.0 ± 1.0, a = −5.0 ± 1.0, b = 30.0 ± 2.0 (according to the Lab color system measured according to JISP8150) ) As a result of adjusting the amount of colorant added while continuously measuring the hue of the colored paper to be produced with an online color sensor, the time from the start of papermaking to the stabilization of the target hue was 20 minutes. .

The yellow dye was not diluted and was continuously added to the wire white water as the undiluted solution. However, since the flow rate of the wire white water is considerably larger than the flow rate of the colorant, the colorant is well dispersed and uneven color occurs on the colored paper. I did not. The green dye was diluted 1000 times and continuously added to the mixing chest.

Since the white water was not colored at the start of the production of colored paper, the amount of colorant required to color the pulp fibers in the white water silo was calculated from the white water silo volume and white water concentration. The dye was not diluted and added to the wire white water all at once.

The method for producing a colored paper of the present invention can be applied to a colored paper for paper making by continuously adding a colorant to a pulp raw material. Further, as a method for adding papermaking chemicals, it can be applied to internal chemicals that have the same fixability to pulp fibers as colorants.

1: seed box 2: white water silo 3: head box 4: paper making wire

Claims (3)

A colored paper manufacturing method for making paper by continuously adding a colorant to a pulp material, wherein at least one colorant is added to a white water silo line from white water under a wire of a paper machine. Production method. The method for producing colored paper according to claim 1, wherein the colorant added to the white water is a basic dye and / or a cationic direct dye. The method for producing colored paper according to claim 1 or 2, wherein the pulp raw material contains 50% or more of waste paper pulp.

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