JP2000034685A - Recycling of resin-containing wastepaper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recycling method for wastepaper printed with a toner for electrophotography or an UV ink and capable of obtaining the finished pulp having high strength and decreased smut by dry-disintegration (defiberization) with little moisture subsequently washing and then beating the resultant pulp. SOLUTION: This recycling method for wastepaper including resinous components is characterized by dry-disintegration under condition that pulp solid concentration is >=70% and washing treatment in the recycling method for reclaimed pulp from wastepaper printed with a toner for electrophotography or an UV ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a dry defibration treatment (fibrillation treatment) in which the waste paper printed with an electrophotographic toner and an ultraviolet curable ink has a low moisture content, and then a washing treatment. The present invention relates to a method for recycling waste paper having high strength while reducing resin foreign matter in a finished pulp.

[0002]

2. Description of the Related Art The utilization rate of waste paper in Japan is 19
As of 1996, it is more than 53%, and has exceeded the majority of pulp raw materials. Furthermore, there is a plan to raise the utilization rate to 56% by the year 2000, and the use of waste paper as a raw material for pulp is expected to increase in the future. However, the use of recycled paper has been slowing in recent years.

[0003] The types of recyclable waste paper include Kamikochi, card, Tokushiro, Nakashiro, White Manila, imitation, color, notch, Nakashirare, newspapers, magazines, cardboard, etc. Recycled paper classified into these categories according to the grade of the product has been used alone or in combination.

[0004] In recent years, the reason why the utilization rate of used paper has slowed down is that the used paper that is easy to recycle has been selectively used. In other words, old paper that is difficult to recycle,
For example, as office waste paper, recycled paper using computer output, xerography, toner printed matter from facsimile, or the like, or waste paper using ultraviolet curable ink (UV ink) used for forms has not been regenerated much.

[0005] Of office waste paper, toner prints contain high-quality chemical pulp, or pulp obtained from high-whiteness pulp can provide high-quality pulp.

[0006] In recent years, the use of UV inks has been rapidly increasing due to labor saving and mass production of printing plants, and it is expected that demand will further increase in the future.

[0007] As a method of recycling and pulping from such waste paper, waste paper is defibrated at a pulp solid content concentration (absolute dry weight of pulp / g of total weight including moisture; hereinafter, abbreviated as pulp concentration) of 20% or less. Generally, recycled pulping is performed through a disaggregation process to obtain a suspension, a rough selection process to separate foreign substances in the pulp suspension, a fine selection process, a deinking process to separate printing ink, and a bleaching process to whiten the color. It is a target.

[0008] However, in the case of a toner print even after the above-mentioned recycled pulping, the toner contains, as a binder, an ester polymer, polyvinyl acetate, an ethylene-vinyl acetate copolymer, a styrene-butadiene copolymer, or the like. With the binder resin as a nucleus and the fibers embraced therein, the finished pulp remains as black spots having a diameter of 100 μm or more. Also, in the case of a UV ink print, a UV curable resin (UV curable resin) having a hard surface is used, so that the UV ink remains as a thin film on the finished pulp after deinking. For this reason, at present, the blending ratio of the toner and the UV ink printed matter with other used paper is severely restricted.

For this reason, various proposals have been made to remove resin-based ink and to recycle waste paper. For example, JP-A-4-91298 and JP-A-4-108197
Japanese Patent Application Laid-Open Publication No. H11-146,086 discloses a method of dissolving and removing a toner print with an organic solvent or the like, but there is a concern that the use of an organic solvent may adversely affect the human body. Further, Japanese Patent Application Laid-Open No. 4-153384 describes a method in which a deinking agent is added, and after aging, deinking is performed by a flotation method. However, even with this method, it is undeniable that a large amount of large particle size toner still remains in the finished pulp. Further, Japanese Unexamined Patent Application Publication No.
No. 2 describes processing at a temperature of 60 to 80 ° C. in the defibration step or the defibration step and the kneading step. As described in the gazette of the publication, in a toner print, the toner binder is firmly fused to the surface of the fiber, and there is a possibility that the toner binder may be easily detached from the fiber to some extent by raising the temperature above the glass transition point of the toner binder. is there.

[0010] However, during the disintegration and kneading, the toner binder which has been staying only on the surface of the fiber until it melts and covers the entire fiber may cause a significant decrease in whiteness. Further, depending on the type of the toner binder, it may be aggregated by application of a temperature and may become tacky, so that it cannot be easily applied. Meanwhile, 19
The Journal of the Japan Pulp and Paper Technology Association, pages 447 to 455, describes in detail "dry dry processing technology for waste office paper", particularly the results of dry disintegration of toner prints. Here, the important point is that dry processing is effective for peeling and dispersing the toner ink. The strength of the dry-processed pulp hand-made sheet was lower than that of the wet-processed pulp in all cases, indicating that damage to the pulp fibers due to the dry process was estimated. Therefore, it is considered that it is difficult to achieve both improvement of the deinking property and maintenance of the pulp quality only by the conventional dry treatment (dry disintegration).

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention performs a defibration process (fibrillation process) in a state in which the used paper printed with an electrophotographic toner and UV ink has a low water content. It promotes fragmentation of the resin in the toner and ink and separation from the fiber, then performs a washing process, and beats the obtained pulp to reduce resin foreign matter in the finished pulp and increase the strength. An object of the present invention is to provide a method for recycling used paper.

[0012]

According to the present invention, there is provided a method for obtaining recycled pulp from waste paper printed with an electrophotographic toner or an ultraviolet curable ink, wherein a dry defibration treatment is carried out when the solid content of the pulp is 70% or more. And a method for recycling used paper containing a resin component, characterized by performing a washing treatment thereafter. Further, the present invention resides in a method for reclaiming waste paper containing a resin component, characterized by beating the washed pulp.

The waste paper materials to be used in the waste paper recycling method used in the present invention include imitation, color, cut, middle and old, newspaper, magazine, cardboard, magazine, etc., but are not necessarily limited to these. Rather, it refers to treated pulp containing printed matter printed with ink containing a resin component.

The pulp to be treated by the dry defibration of the present invention may be a pulp that has been subjected to a rough-selection treatment or a mechanical dispersion treatment such as kneading as a pre-treatment, or a pulp that has been subjected to a mechanical What performed distributed processing may be sufficient.

The pulp concentration at the time of dry defibration is preferably at least 70%, particularly preferably at least 90%. When the pulp concentration is less than 70%, water acts as a buffer between the fibers and the defibrillator, and good defibration of fibers and fragmentation of ink cannot be obtained.

Various machines actually exist as a defibration or defibration device used for dry defibration, but a device capable of processing a wide variety of paper qualities, having little damage to fibers, and capable of taking out long fibers. Is required. For example, a refiner used in the manufacture of groundwood pulp, a dry disintegrator (trade name: cleaning separator) of Ein Engineering Co., Ltd., which is effective in separating a polymer film such as a milk pack from wood fiber, and Kobe Steel There is a dry disintegration device (trade name: Eco Pulper) manufactured by the company. Of these devices, any device that can take out one or several fibers from paper at a pulp concentration of 70% or more may be used. However, it should be noted that dry disintegration is a method of extracting fibers from waste paper, and therefore it is desirable to minimize fiber deterioration. Therefore, when using a refiner or the like, it is necessary to devise measures such as widening the clearance.

The processing time in dry disaggregation may be sufficient time for disintegration. For example, in the case of dry disintegration manufactured by Ein Engineering, stirring is performed for about 1 to 2 minutes. If this is the case, sufficient pulping pulp can be obtained with only one pass.

The pulp after dry defibration is preferably diluted to a pulp concentration of 20% or less for washing, and particularly preferably a pulp concentration of 10% or less is selected. 20
If the pulp concentration exceeds 100%, the washing becomes insufficient and the residual ink tends to remain.

As the washing step, a known apparatus may be used as long as the fiber can be washed and the ink content can be removed. There is no particular limitation, but the pulp concentration is temporarily reduced, for example, using a diffuser washer, a drum washer, an extractor, or the like. After that, a combination of a plurality of washing methods, i.e., a dilution dehydration method for increasing the pulp concentration, and a flotation method for selectively removing a product having a center of about several tens of microns to about 100 microns using a flotator or the like, while checking the degree of washing You can choose from the methods.

Further, if a defibration step using a pulper or the like is added in the dilution treatment before the washing step, the degree of peeling of the ink from the fibers is further improved.

The pulp after the washing step is subsequently beaten. Here, the beating treatment refers to a step of cutting or fibrillating the fiber, and is performed by selecting from various types of conical, drum, and disk refiners. Further, it is preferable that the degree of beating is reduced by a width of 50 ml or more with respect to the value of the Canadian Standard Freeness (hereinafter simply referred to as freeness) in an unbeaten state. Although a specific range cannot be determined unconditionally because it differs depending on the type of the product, the freeness value should be within a range of 100 to 500 ml.

Regarding the reason why the dry disaggregation improves the deinking property of the resinous ink, first, in the dry disaggregation, when the fibers are made into a single fiber, the cured resinous ink is shredded by energy transmission close to impact. At the same time, it separates from the fiber. After that, by performing the dilution washing method, the flaked ink can be removed, and even some ink that is not flaked can be separated from the fiber so that the ink can be removed efficiently in the flotation process etc. it is conceivable that. On the other hand, in the resin ink in the conventional deinking process using wet disintegration, sufficient fragmentation does not proceed because water acts as a buffer material. In addition, it is difficult to separate the ink from the fiber even with the ink that strongly adhered to the fiber, and it was not removed by dilution or flotation washing. Will remain.

It is considered that the reason why the fibers can have high strength is that the fibers have a certain degree of elasticity as compared with the resinous ink, so that damage to the fibers is small and the decrease in strength is small. Further, the pulp after the dry disintegration was observed with a microscope, and it was found that the fluff of the fibers was smaller than that in the wet disintegration. In other words, it can be said that single fibers were formed by removing fluffs involved in bonding fibers during dry defibration. Therefore,
It is considered that hydrogen bonding between fibers increases for the first time by performing new beating, and high strength is imparted.

In the method for recycling used paper of the present invention, the pulp that has been defibrated by dry disaggregation is then diluted and washed in a washing step to remove the ink pieces that have been fragmented by dry disaggregation. In addition, the peeling of the ink proceeds by adding a disintegration process using a pulper or the like before the dilution washing,
The effect of dilution washing is improved. After diluting and washing, a plurality of steps selected from kneading (kneading or disperser treatment), aging (soaking or bleaching), washing (flotator, cleaner, washer), beating (refiner, beater), etc. By combining them, it is possible to obtain a pulp having high whiteness and strength. In addition, an enzyme treatment such as cellulase or hemicellulase may be provided in a part of the process for the purpose of reducing the addition of chemicals and improving pulp quality.

[0025]

EXAMPLES The present invention will be described more specifically with reference to examples and comparative examples below, but of course the present invention is not limited to these examples. The addition ratios in Examples and Comparative Examples are shown by weight% based on absolute dry pulp.

Example 1 (1) Dry disintegration processing: PPC paper on which toner printing has been performed using an electronic copying machine manufactured by Fuji Xerox Co., Ltd. is cut into 6 mm × 12 mm by a shredder. The cut sample was put into a dry disintegration device (cleaning separator) manufactured by Ein Engineering Co., Ltd., and circulated in the device for about 2 minutes to obtain a dry disintegration pulp passed through a 2 mm mesh. (2) Dilution washing process: Pulp slurry after disintegration is 150
Open on mesh wire, then 10g pulp solids
The diluted washing was performed at a rate of 1 liter of ion-exchanged water per unit. The washed pulp was centrifugally dehydrated to a pulp concentration of 30% to obtain a test pulp. (3) Aging treatment: Take a predetermined amount of the test pulp of (2) in a plastic bag, and then add water and a chemical solution (caustic soda 0.6%, hydrogen peroxide 1.0%) to a pulp concentration of 25%. .
The pulp was aged in a water bag at 70 ° C. for 2 hours by aging in a plastic bag containing a sample that was well stirred by hand. (4) Kneading treatment: The aged pulp was continuously subjected to kneading treatment using a biaxial kneader (manufactured by Yamamoto Hyakuma Seisakusho). The kneading conditions were as follows: pulp concentration 25%, 30
Two passes at ℃. (5) Flotation washing treatment: The kneaded pulp is diluted to 1.2% with ion-exchanged water, and then put into a floatator (manufactured by Kyoshin Sangyo Co., Ltd.), and then a nonionic deinking agent DI1020.
(Manufactured by Kao Corporation) at a solid concentration of 0.3%, and an anionic DI370 (manufactured by Kao Corporation) as a foaming agent at a solid concentration of 0.0
After adding 1%, it was prepared with ion-exchanged water so that the pulp concentration became 1.0%. After adjusting the pulp slurry, flotation treatment was performed at 30 ° C. for 10 minutes at an air intake of 2.6 L / min. (6) Dewatering treatment: After the flotation washing treatment, the pulp is dewatered to 15% with a 150 mesh wire and further diluted to 1% and then 2
Dehydrated to 5%. (7) Beating: After dehydration treatment of (6), the pulp was diluted to an absolute dry weight of 30 g to a pulp concentration of 10%, and further heated to a temperature of 3%.
After the temperature was adjusted to 0 ° C., the beating was carried out using a PFI mill with a clearance of 0.25 mm to obtain a finished pulp.

Example 2 The dry disaggregation treatment of (1), the dilution washing treatment of (2), the flotation washing treatment of (5), the dewatering treatment of (6), and the beating of (7) by the method described in Example 1. Processing was performed to obtain a finished pulp.

Example 3 A finished pulp was obtained in the same manner as in Example 2 except that waste paper printed with UV ink was used.

Comparative Example 1 The toner print used in Example 1 was cut into a size of 6 mm × 12 mm. Dilute the cut sample to 2% pulp consistency,
Example 1 was repeated except that the disintegration was performed at 30 ° C. for 10 minutes using a Tappi disintegrator (hereinafter, the process of removing pulp fibers via water from the paper shape is referred to as wet disintegration for convenience in comparison with dry disintegration). The same treatment was performed to obtain a finished pulp.

Comparative Example 2 Wet disaggregation was performed instead of dry disaggregation, and the dilution washing treatment of (2), the flotation washing treatment of (5), the dewatering treatment of (6) and (7) ) Was processed to obtain a finished pulp.

COMPARATIVE EXAMPLE 3 A dry-disintegration treatment of (1), a dilution washing treatment of (2), a flotation washing treatment of (5) and a dehydration treatment of (6) were completed by the method described in Example 1. Obtained as pulp.

Comparative Example 4 A finished pulp was obtained in the same manner as in Comparative Example 3, except that wet disintegration was performed instead of dry disintegration.

Comparative Example 5 A finished pulp was obtained in the same manner as in Example 3 except that wet disintegration was performed instead of dry disintegration.

[0034]

[Table 1]

(Measuring method of pulp quality and strength) The whiteness was measured by Suga Test Instruments Co., Ltd., spectral whiteness colorimeter SC-10WN.
Was used to determine the ISO whiteness. Tensile strength is JIS P
It was shown as the breaking length using 8113. The tear strength is JI
It was shown as a specific tear strength using SP8116. The finished pulp of Examples 1, 2, and 3 and Comparative Examples 1, 2, and 5 was adjusted to 450 ml in Canadian Standard Freeness using a PFI mill.
A sheet of 0 g was prepared and a strength comparison test was performed. For the measurement of the residual ink, a dot analyzer DA5000 manufactured by Oji Scientific Instruments was used to count toner particles having a particle size of 16 μm or more for an area of 100 square centimeters, and the residual ink ratio and the diameter were converted to 100 μm.
The above ink particle size number was calculated.

As is clear from Table 1, the finished pulp obtained by the present invention has a small amount of resinous foreign matter in the pulp and can obtain a pulp having a high strength (Examples 1 to 3). On the other hand, the pulp which was disintegrated only by wet disintegration according to the conventional method without dry disintegration had many resinous foreign substances (Comparative Examples 2, 3, 4, and 5). Alternatively, the amount of resinous foreign matter is smaller than that of other wet disaggregation, but the pulp is inferior in strength as compared with the examples (Comparative Example 1). Further, even if dry disintegration is performed, pulp having poor strength is obtained without beating treatment (Comparative Example 3).

[0037]

As is apparent from the above description, the method of the present invention for regenerating waste paper printed with the toner for electrophotography and UV ink reduces the amount of foreign resin particles in the finished pulp when compared with the conventional method. This has made it possible to produce pulp having high strength.

Claims (1)

[Claims] In a method for obtaining recycled pulp from waste paper printed with an electrophotographic toner or an ultraviolet curable ink, dry defibration is performed at a solid content of pulp of 70% or more, followed by washing. A method for recycling used paper containing a resin component.