JP2005336677A - Method for producing waste paper pulp for recording paper and recording paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing waste paper pulp for recording paper with which the recording paper of uniform quality can be obtained even when the waste paper pulp is used and occurrence of paper breakage during papermaking can be reduced. <P>SOLUTION: The method for producing the waste paper pulp for the recording paper comprises the following steps. a disintegration step of disintegrating nonselected waste paper and providing a pulp fiber suspension, a coarse screening step of removing impurities from the pulp fiber suspension, a flotation step of removing ink/impurities from the pulp fiber suspension from which the impurities are removed by flotation and a step of carrying out a beating treatment of the pulp fibers contained in the pulp fiber suspension from which the ink/impurities are removed and providing 0.70-1.00 mm Kajaani average fiber length of the pulp fibers. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing waste paper pulp for recording paper, and a recording paper containing pulp obtained by the method for producing waste paper, and in particular, the waste paper used as a raw material includes back glue such as hot melt, a compact disc, and the like. The present invention relates to a method for producing waste paper pulp suitable for the case.

  Waste paper pulp, which is the raw material for recycled paper, dissolves waste paper that is difficult to produce many kinds of contaminants such as newspapers and leaflets into a suspension, and then removes impurities, deinks, and bleaches. In general, the paper is manufactured in order, and used paper such as magazines and books is rarely used. Old paper such as magazines and books may have reduced productivity because back glue such as hot melt remains, or compact discs (hereinafter simply referred to as CDs), etc., are sandwiched between pages. Further, this is because the quality of recycled paper may be deteriorated, and troubles may occur during printing.

However, from the viewpoint of effective use of resources, it is desirable to use used paper such as magazines and books. In particular, if waste paper such as magazines and books can be used without sorting from waste paper such as newspapers and flyer papers, it is also preferable in that the waste of sorting waste paper can be saved.
Therefore, the applicant of the present invention can use waste paper containing hot-melt and alkali-meltable materials such as hot melt and CD as it is without sorting, as disclosed in Japanese Patent Laid-Open No. 2002-155482. An economical method for producing waste paper pulp was proposed.

Japanese Patent Laid-Open No. 2002-155482

  The waste paper pulp manufacturing method disclosed in the above publication has generally solved the separation and removal of coarse impurities such as hot melt and CD. However, when the waste paper used as a raw material is not selected, there is a disaggregation freeness in the raw waste paper. Even if there is waste paper containing good quality pulp fibers (hereinafter also referred to as good quality waste paper) that is 350 cc or more, waste paper (hereinafter referred to as poor waste paper) containing other poor quality pulp fibers (with a disaggregation freeness of 300 or less). It was difficult to improve the quality of the used waste paper pulp. In addition, unsorted waste paper is a main cause of fluctuations in the quality of waste paper pulp because the mixing ratio of good quality waste paper and poor waste paper is not constant. Therefore, it has still been difficult to produce high-quality waste paper pulp using unselected waste paper as a raw material, and to produce recording paper that can be used for recording from waste paper pulp made from unselected waste paper.

  Then, the main subject of this invention is providing the pulp manufacturing method for manufacturing the used paper pulp which can obtain the recording paper of uniform quality from unsorted used paper. Another problem is to stabilize the quality of waste paper pulp obtained from unsorted waste paper and recording paper made from it.

  As a result of intensive studies to achieve the above object, the inventors of the present invention disaggregated unselected waste paper to obtain a pulp fiber suspension; a coarse selection step of removing impurities from the pulp fiber suspension; A flotation step of removing ink and contaminants from the pulp fiber suspension from which the contaminants have been removed by flotation; and beating the pulp fibers contained in the pulp fiber suspension from which the ink and contaminants have been removed; The present invention was completed by obtaining the knowledge that a method for producing waste paper pulp for recording paper having a step of setting the mean fiber length of the pulp fibers to a specific range can achieve the above-mentioned object.

  The present invention has been made based on the above knowledge, a disaggregation step of disaggregating unselected waste paper to obtain a pulp fiber suspension; a rough selection step of removing impurities from the pulp fiber suspension; Flotation process for removing ink and contaminants from the pulp fiber suspension from which the ink has been removed; and pulp fibers contained in the pulp fiber suspension from which the ink and contaminants have been removed by beating the pulp fiber The present invention provides a method for producing waste paper pulp for recording paper, characterized by comprising a step of setting the average fiber length of the paper to 0.70 mm to 1.00 mm.

  In the conventional method of producing waste paper pulp from sorted waste paper raw materials, fiber beating was performed, but in the method of producing waste paper pulp from unsorted waste paper, the fiber length manipulation of the fiber is unknown. Unlike the conventional waste paper pulp manufacturing method, which uses unsorted waste paper as raw material, it is different from the conventional manufacturing method, such as the removal operation of CD, vinyl and other foreign matters. It has the process of. Further, the quality of the contained fibers (fibers to be beaten) and the width of the fiber length are also different. Therefore, even if the beating process is simply incorporated in the process according to the conventional manufacturing method, the effect of the present invention cannot be obtained. The above-described present invention has been completed as a result of earnestly researching which stage and in what form the beating operation should be performed by the present inventors in such an unprecedented situation. And according to the present invention, after removing impurities derived from unsorted waste paper such as CD and vinyl, and after further flotation treatment, the average fiber length of the pulp fibers is 0.70 mm to By setting the thickness to 1.00 mm, waste paper pulp applicable to recording paper or the like can be obtained from unselected waste paper.

The method for producing waste paper pulp for recording paper preferably includes a step of adding a cationic coagulant to the pulp fiber suspension before beating the pulp fiber suspension.
By adding a cationic coagulant to the pulp fiber suspension before the beating treatment, the ash is condensed on the used paper pulp, and a used paper pulp having a high ash content and high whiteness is obtained. Thus, it is possible to prevent the ash from flowing out after the raw material adjustment step of the paper machine using waste paper pulp to suppress the variation in drainage at the paper making stage, and to reduce the cost of use by reducing the filler used.

Further, the present invention is a recording paper produced by making a pulp raw material containing waste paper pulp for recording paper obtained by the above method for producing waste paper pulp for recording paper, wherein the recording paper is evenly distributed in the Z-axis direction. Alternatively, a recording sheet is provided that is divided into two almost evenly and the difference in the mean length of the crabs on the front and back surfaces is 0.2 mm or less.
In recording paper, it is necessary to stably supply paper with excellent smoothness on the paper surface, and in the papermaking stage, it is necessary to accurately adjust the beating degree and fiber length of the raw pulp. The used paper pulp used in the present invention is the use of used paper pulp having an average fiber length of Kayani in a predetermined range, and by adjusting the ash content that causes the drainage fluctuation of the raw material pulp, which is a problem at the paper making stage, by a coagulant Fluctuation at the wet end is extremely small, and the paper that has been made is divided equally or nearly equally in the Z-axis direction, and the difference in mean fiber length between the crabs on the divided front and back surfaces is kept within 0.2 mm. This makes it possible to stably supply paper with excellent smoothness.
The recording paper is preferably coated on the surface with a coating liquid.

  According to the used paper pulp manufacturing method of the present invention and the recording paper using the used paper pulp of the present invention, even when used paper pulp is used as a raw material, it is possible to obtain a recording paper of uniform quality, Occurrence can be reduced.

Hereinafter, the method for producing waste paper pulp for recording paper of the present invention will be described.
The method for producing waste paper pulp for recording paper of the present invention comprises a disaggregation step of disaggregating unselected waste paper to obtain a pulp fiber suspension; a roughing step of removing contaminants from the pulp fiber suspension; A flotation process for removing ink and contaminants from the pulverized pulp fiber suspension by flotation; and pulp fibers contained in the pulp fiber suspension from which the ink and contaminants have been removed are beaten to obtain a mean of pulp fibers A step of setting the fiber length to 0.70 mm to 1.00 mm.

  In the present invention, the unsorted used paper means used paper that also contains used paper such as magazines and books, and coated paper. Old paper such as magazines and books has back glue such as hot melt remaining, and CDs etc. are sandwiched between pages as an appendix, so usually such magazines and books are selected to produce pulp However, in the present invention, used paper such as magazines, books and coated papers is used without sorting.

  In the method for producing waste paper pulp for recording paper of the present invention, unsorted waste paper is first disaggregated to obtain a pulp fiber suspension. In the present invention, raw paper containing unselected waste paper is used as the raw paper, and for example, waste paper such as printing paper, newspaper, magazine, OA waste paper, flyer waste paper, etc. may be included. There is no particular limitation on the ratio of unselected waste paper in the waste paper used as a raw material in the waste paper pulp manufacturing method for recording paper of the present invention, but it is more effective when the raw waste paper contains at least 50% by mass or more. is there.

In the method for producing waste paper pulp for recording paper of the present invention, a conventionally known method can be used without particular limitation as a method for obtaining a pulp fiber suspension by disaggregating waste paper.
For example, when used paper is disaggregated using a pulper, it is preferable that water is added to the used paper to make the used paper concentration about 2 to 5% by mass. The pH during the disaggregation treatment is preferably about 4 to 10, the temperature is preferably about 10 to 60 ° C., and the stirring speed is preferably about 900 to 2500 rpm (concentration 3% by mass).

Next, in the coarse selection step, impurities such as CD and vinyl are removed from the pulp fiber suspension.
A conventionally known method can be used as a method for removing impurities from the pulp fiber suspension. For example, a low-vibration flat screen, a low-vibration rotary screen, a high-vibration flat screen, a high-vibration rotary screen, a centrifugal force type screen, an overflow cleaner, and the like can be given.

  Next, ink and contaminants (unreleased waste paper, lightweight foreign matter (plastic, synthetic resin, synthetic fiber, etc.)) are removed by flotation from the pulp fiber suspension from which the contaminants have been removed in the rough selection step (flotation step) ). Flotation is a method of adsorbing and separating ink, contaminants, and the like into bubbles, and a conventionally known method can be used as a flotation method. For example, there are a bubble generation method using a rotating air diffuser tube type, a micro bubble type using a high-speed turbine, and a special injector.

  In the waste paper pulp manufacturing method for recording paper of the present invention, after the flotation step, the pulp fibers in the pulp fiber suspension are beaten so that the average fiber length of the pulp fibers is 0.70 mm to 1.00 mm. . By beating the pulp fiber, the freeness value of the pulp contained in the pulp fiber suspension becomes a constant value, so the quality of the pulp is homogenized and the wet end during paper making does not fluctuate. The recording paper that is included has little variation in quality, and the occurrence of paper breakage during papermaking is reduced.

  In the used paper pulp manufacturing method of the present invention, the pulp fiber suspension is beaten, and the average fiber length of the used paper pulp contained in the pulp fiber suspension is 0.70 mm to 1.00 mm, preferably 0. .80 to 0.90 mm. If the average fiber length of the pulp fiber after beating is less than 0.70 mm, the beating power consumption will increase and the cost will increase, the pulp strength will decrease, the ash yield will decrease due to the coagulant, and there will be variations. Arise. On the other hand, if it exceeds 1.0 mm, the drainage fluctuation at the wet end becomes large, resulting in a problem that the smoothness is not stable. In the present specification, “kayani average fiber length” means a weight average fiber length measured using a kayani fiber length measuring machine (FS-100, manufactured by Kayani Automation Co., Ltd.).

  As a method for beating the pulp fiber, a conventionally known method can be used without particular limitation, and for example, it can be carried out using a beater such as various refiners or PFI mills. The waste paper pulp concentration when the pulp fiber suspension (waste paper pulp) is beaten is preferably about 2 to 5% by mass, and more preferably about 3 to 4% by mass. In addition, the pH of the pulp fiber suspension during the beating treatment is preferably about 4 to 10, and the temperature is preferably about 10 to 60 ° C. The beating speed is preferably 900-2500 rpm. In order to make the mean fiber length of the pulp fiber within the above range, it is easily carried out by adjusting the load of the beating device such as pulp concentration, processing time, beating speed, pH of pulp fiber suspension, etc. can do.

  In the method for producing waste paper pulp for recording paper of the present invention, it is preferable to add a cationic coagulant to the pulp fiber suspension before beating the pulp fiber. By adding a cationic coagulant to the pulp fiber suspension, anionic trash present in the pulp fiber can be removed. Further, by adding a cationic coagulant to the pulp fiber suspension before the beating treatment, ash is condensed on the used paper pulp, and used paper pulp having high ash content and high whiteness can be obtained. As a result, it is possible to prevent ash outflow after the raw material adjustment step of the paper machine using waste paper pulp and suppress the fluctuation in drainage at the paper making stage, and to reduce the cost of use by reducing the filler used.

  Moreover, it is preferable that the used paper pulp raw material to which a coagulant is added has a pulp concentration of 2 to 5% by mass, a temperature of 20 to 60 ° C., and a pH of 4 to 10. And the addition amount of a coagulant | flocculant is 100-1000 weight ppm with respect to the absolute dry pulp. If the amount is less than 100 ppm by weight, sufficient effects are not exhibited. If the amount exceeds 1000 ppm by weight, problems such as pipe contamination may occur.

  Furthermore, in the present invention, in the step of adding a cationic coagulant to the pulp fiber suspension before the beating treatment of the pulp fiber, the cationic coagulant is added to the pulp fiber suspension, and the cation requirement of the pulp fiber Is preferably 0 to 0.2 meq. By setting the cation requirement in the range of 0 to 0.2 meq, it is possible to suppress fluctuations in drainage at the wet end, improve the ash content of recycled paper recycled pulp, reduce discharge dredging, and reduce the use of new fillers. it can.

The cationic coagulant is not particularly limited as long as it is a coagulant exhibiting cationic properties. For example, polydiallyldimethylammonium chloride (pDADMAC) or a derivative thereof, diallyldimethylammonium chloride and other monomers. Examples thereof include a copolymer, aluminum sulfate, polyacrylamide, polyamine, polyethyleneimine, 2- (methacryloyloxy) ethyltrimethylammonium chloride polymer, and modified polyethyleneimine.
The amount of the cationic coagulant used is an amount necessary to bring the required cation amount of the used paper pulp into the above range, and specifically, about 100 to 1000% by mass per the absolute dry mass of the pulp. If the amount is less than 100% by mass, the coagulation effect may not be sufficiently exerted. If the amount exceeds 1000% by weight, excessive additives may leak and form a lump of dust in the feed pipe, which is not preferable.

Next, the recording paper of the present invention will be described.
The recording paper of the present invention is manufactured by papermaking a pulp raw material containing the used paper pulp obtained by the above-described used paper pulp manufacturing method of the present invention. The recording paper of the present invention may contain pulp other than the waste paper pulp obtained by the above-mentioned waste paper pulp manufacturing method, and the pulp to be blended in addition to the waste paper pulp is GP, PGW, RMP, TMP, CTMP. Well-known pulp such as mechanical pulp such as CMP and CGP, wood pulp such as chemical pulp such as LBKP and NBKP, and non-wood pulp such as kenaf, bagasse, hemp, straw, bamboo, straw and linter can be suitably used.

  The mixing ratio of the waste paper pulp in the recording paper of the present invention in the total pulp is preferably 50% by mass or more, and more preferably, from the viewpoint of environmental protection and recycling, the stable paper surface smoothness in the present invention is obtained. Therefore, it is preferable to blend 70% by mass or more, and the use of 100% can exhibit the effect of the present invention most.

The recording paper of the present invention is divided into two equally or substantially uniformly in the Z-axis direction (paper thickness direction), the difference in the mean fiber length between the divided front and back surfaces is 0.2 mm or less, Preferably it is 0.1 mm or less. If the difference in mean fiber length between the front and back of the divided surface exceeds 0.2 mm, the difference between the front and back of the paper surface will increase, and the appearance will deteriorate in printing such as double-sided printing that is frequently used recently. The transportability, operability, and handling in the recording apparatus are deteriorated.
Although there is no restriction | limiting in particular in the method of making the difference of the said Kayani average fiber length into the said range, For example, it can implement by a post refiner and a kneader.

Moreover, the average length of the squirrels obtained by dividing the recording paper obtained by making the waste paper pulp obtained by the method for producing waste paper pulp of the present invention into two equal or almost evenly in the Z-axis direction, The measurement can be carried out by separating the front and back using a sheet splitter (manufactured by Kumagai Riki Kogyo Co., Ltd.), but the method described in JP-A-03-69694 is preferably employed.
Kayani average fiber length was measured using disintegrated pulp with a solid content concentration of 1% by mass and disaggregated for 25 minutes using a standard Tappi disaggregator (based on JIS P 8209) for the front and back layers separated into two layers almost uniformly. can do.

  An internal sizing agent may be added to the recording paper of the present invention. Examples of the internally added sizing agent include known rosin sizing agents, alkenyl succinic anhydride, alkenyl ketene dimer, and the like. The addition amount of the internal sizing agent is preferably 0.03 to 0.3% by mass with respect to the absolute dry mass of the pulp. When the amount added is less than 0.03% by mass, for example, when offset printing is performed on the obtained recording paper, the paper strength of the paper may decrease due to water absorption of the dampening water, and trouble may occur that causes the paper to be cut. If it exceeds 0.3 mass%, an increase in hole defects due to the sizing agent may occur.

  Further, a surface sizing agent may be applied to the surface of the obtained recording paper and dried. Examples of the surface sizing agent include known ones such as acrylic or styrene. The addition amount of the surface sizing agent is preferably 0.06 to 0.3% by mass with respect to the absolute dry mass of the pulp. When the addition amount is less than 0.06% by mass, similarly to the internally added size, when offset printing is performed on the obtained recording paper, the paper strength may be reduced due to water absorption, and a paper-cutting trouble may occur. Further, coating exceeding 0.3% by mass is not preferable because the amount of the surface sizing agent is excessive.

  Further, a filler may be added to the recording paper of the present invention as necessary. Examples of fillers include inorganic pigments such as light calcium carbonate, heavy calcium carbonate, magnesium carbonate, talc and kaolin, organic pigments such as melamine resin and urea resin, paper strength enhancer, conductive agent, yield improver, drainage An improving agent etc. are mentioned.

Further, with the recent increase in environmental protection, users are demanding recording papers with increased bulk in order to make effective use of pulp for paper manufacture produced from forest resources.
Furthermore, a bulking agent may be added to increase the bulk of the recording paper. Any compound that can increase the bulk of the recording paper can be used without particular limitation. Examples of the bulking agent used include compounds having a hydrophobic group and a hydrophilic group in the molecule. For example, a surfactant can be used. Examples of such surfactants include ester compounds of higher alcohols and higher fatty acids. Other examples of usable bulking agents include aliphatic polyamidoamine compounds. As the bulking agent, commercially available ones can be used, for example, BASF's Sulsol VL, Bayer's Bi-Volume P Liquid, Sanki's React Pake, Kao's KB-08T, KB-115 Etc.
The addition amount of the bulking agent is preferably 10 kg / t or less with respect to the pulp from the viewpoint of suppressing the strength reduction of the product.

  The cationized starch used for the purpose of improving the yield of the bulking agent for paper (cationization degree 0.030 to 0.050) is less than 5 kg / t of pulp, and the yield of the bulking agent for paper is too low. If it exceeds 15 kg / t, the yield improvement effect is not seen for the cost increase.

There is no particular limitation on the method for papermaking the recording paper of the present invention, and papermaking can be performed using a long paper machine, a circular paper machine, a twin wire paper machine, or the like.
The recording paper of the present invention may be subjected to machine calendar processing as necessary.
The basis weight of the recording paper of the present invention can be appropriately set according to the intended use. Generally, when used for printing, paper of about 50 g to 160 / m ² is preferably used.

The recording paper of the present invention may be coated with a coating liquid on the surface thereof. By applying the coating liquid, there is an effect that printing suitability, glossiness, smoothness, and appearance are improved. As the coating liquid, paints such as starch, oxidized starch, processed starch, carboxymethylcellulose, polyacrylamide, polyvinyl alcohol, latex and the like can be used. The coating amount is preferably ² to 50 g / m ^{2 in} terms of solid content, but is preferably adjusted in the range of about 5 to 30 g / m ² in consideration of the white paper quality of the obtained coated paper, printing suitability, and the like.
Note that other appropriate fillers (for example, calcium carbonate, talc, etc.) and chemicals (for example, an internal paper strength enhancer, a yield improver, etc.) may be used as necessary. In addition, the coating liquid used in the present invention uses various auxiliaries blended in ordinary coated paper pigments such as dispersants, thickeners, water retention agents, antifoaming agents, water resistance agents, and lubricants. You may do it.

As a method for applying the coating liquid to the surface of the recording paper, either an on-machine coater or an off-machine coater may be used. For example, a known coating method such as an air knife coater, a curtain coater, a die coater, a blade coater, a gate roll coater, a bar coater, a rod coater, a roll coater, a bill blade coater, a short L blade coater, or a spray coater can be employed. When applying the coating liquid to the surface of the recording paper, the coating liquid may be applied to one side or both sides of the recording paper.
The coating recording paper of the present invention can be suitably used as a printing paper.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited thereto. In the following examples, “parts” and “%” represent “parts by mass” or “% by mass” unless otherwise specified.
Example 1
Unsorted raw paper (including 92% magazine-based waste paper and 8% high-quality waste paper) was disaggregated with a pulper to obtain a pulp fiber suspension. Then, CD pulp fiber suspension, after removing the contaminants vinyl etc., the ink non defibration paper with floater coater, to remove impurities such as lightweight foreign matters, then dehydrated, the H ₂ O _{2 2.} 1% by mass (per dry pulp mass), 2.2% by mass of NaOH, and 0.7% by mass of Na ₂ SiO ₃ were added, bleached at 60 ° C. for 3 hours, and re-flowed with a flowmeter. After deinking, the pH of the pulp fiber suspension was adjusted to 6, and polydiallyldimethylammonium chloride was added as a cationic coagulant to a concentration of 50 ppm. Next, beating treatment was performed at a beating speed of 2500 rpm and a temperature of 60 ° C. so that the average fiber length of the pulp fiber was 0.7 mm, and a waste paper pulp for recording paper having an ISO whiteness of 80% was obtained. Obtained. About the obtained used paper pulp for recording paper, the average fiber length and cation requirement amount were calculated | required as follows. The evaluation results are shown in Table 1.

Using the mixed pulp obtained by mixing 70 parts of LBKP and 20 parts of NBKP to 10 parts of the used waste paper pulp for recording paper, paper is made at 800 m / min with a twin wire paper machine, and the weight is 64 g / m. ^Two recording sheets were obtained. About the obtained recording paper, the two-part kayani average fiber length, the cation requirement, the ISO smoothness, and the formation evaluation were obtained as follows using a kayani fiber length measuring device. Further, the wet operation stability was also evaluated as follows. The evaluation results are shown in Table 1.

Evaluation Method (1) Kayani Average Fiber Length of Waste Paper Pulp This was measured with a Kayani average fiber length measuring machine (FS-100, manufactured by Kayani Automation Co., Ltd.).
(2) Cation requirement amount Collect 5g of waste paper pulp by dry mass, add 1kg of distilled water to this, disaggregate the sample with a standard disintegrator used for the handsheet preparation method for pulp test, and make particles made by CyberMetrics, USA The amount of cation required was measured by the name of the surface charge measuring device Cyber Charge.
(3) Two-part Kayani average fiber length difference The obtained recording paper was divided into two almost evenly in the Z-axis direction using a sheet splitter (manufactured by Kumagai Riki Kogyo Co., Ltd.). The average fiber length was measured in the same manner as (1), and the difference between each was determined.

(4) ISO smoothness Measured with an ISO smoothness tester.
(5) Formation evaluation The formation was evaluated visually. Evaluation was performed according to the following evaluation criteria.
○: The formation was uniform.
(Triangle | delta): There was unevenness of formation, but it was an acceptable level.
X: The formation unevenness was large.
(6) Stability of wet end operation The presence or absence of fluctuations in drainage in the test machine was visually determined. Evaluation was performed according to the following evaluation criteria.
○: No variation occurred Δ: There was variation, but it was at an acceptable level.
X: The variation was large.

Example 2
Before the beating treatment, a cationic coagulant is added to the pulp fiber suspension so that the concentration becomes 100 ppm, the temperature during the beating treatment of the pulp fiber suspension is 40 ° C., the beating speed is 2000 rpm, Except that the beating process was performed so that the average fiber length of the crabs was 0.8 mm, the same operation as in Example 1 was performed to obtain used paper pulp for recording paper. The obtained waste paper pulp for recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
A recording paper was obtained in the same manner as in Example 1 except that 30 parts of the obtained waste paper pulp for recording paper was mixed pulp obtained by mixing 45 parts of LBKP and 25 parts of NBKP. The obtained recording paper was operated in the same manner as in Example 1 to obtain a recording paper having a basis weight of 64 g / m ² . The obtained recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 3
Before the beating treatment, a cationic coagulant is added to the pulp fiber suspension so that the concentration becomes 500 ppm, the temperature during the beating treatment of the pulp fiber suspension is 40 ° C., the beating speed is 1600 rpm, Except that the beating treatment was performed so that the average fiber length of the fibers was 0.9 mm, the same operation as in Example 1 was performed to obtain used paper pulp for recording paper. The obtained waste paper pulp for recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
Using mixed pulp obtained by mixing 75 parts of LBKP and 15 parts of NBKP to 10 parts of the used waste paper pulp for recording paper, AKD (Nippon PMC Co., Ltd.) was used for 100 parts of pulp in terms of solid content as an internal sizing agent. Manufactured, SS-362) 0.3 part was added, and paper making was performed at 800 m / min with a twin wire paper machine to obtain a recording paper having a basis weight of 64 g / m ² . The obtained recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 4
Before the beating treatment, a cationic coagulant is added to the pulp fiber suspension so that the concentration becomes 1000 ppm, the temperature during the beating treatment of the pulp fiber suspension is 40 ° C., the beating speed is 1000 rpm, Except that the beating process was performed so that the average fiber length of the fibers was 1.0 mm, the same operation as in Example 1 was performed to obtain used paper pulp for recording paper. The obtained waste paper pulp for recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
Using mixed pulp obtained by mixing 80 parts of LBKP and 10 parts of NBKP to 10 parts of the used waste paper pulp for recording paper, AKD (Japan PMC Corporation) Manufactured, SS-362) 0.3 part was added, and paper making was performed at 800 m / min with a twin wire paper machine to obtain a recording paper having a basis weight of 64 g / m ² . The obtained recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 5
Before the beating treatment, a cationic coagulant is added to the pulp fiber suspension so that the concentration becomes 2000 ppm, the temperature during the beating treatment of the pulp fiber suspension is 40 ° C., the beating speed is 1000 rpm, Except that the beating process was performed so that the average fiber length of the fibers was 1.0 mm, the same operation as in Example 1 was performed to obtain used paper pulp for recording paper. The obtained waste paper pulp for recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
A recording paper having a basis weight of 64 g / m ² was obtained in the same manner as in Example 1 except that only the obtained waste paper pulp for recording paper was used. The obtained recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Comparative Example 1
The pulp paper suspension was not beaten and the operation was performed in the same manner as in Example 1 except that the cationic coagulant was not added to obtain used paper pulp for recording paper. The obtained waste paper pulp for recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
Using mixed pulp obtained by mixing 75 parts of LBKP and 15 parts of NBKP to 10 parts of the used waste paper pulp for recording paper, AKD (Arakawa Chemical Co., Ltd.) was used for 100 parts of pulp in terms of solid content as an internal sizing agent. Ltd., SP287) was added 0.2 part performs paper at 800 m / min at a twin-wire paper machine, basis weight was obtained recording paper 64 g / ^{m 2.} The obtained recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Comparative Example 2
The operation was performed in the same manner as in Example 1 except that the temperature during the beating treatment of the pulp fiber suspension was 30 ° C., the beating speed was 3000 rpm, and the cationic coagulant was added to a concentration of 45 ppm. Waste paper pulp for paper was obtained. The obtained waste paper pulp for recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
Using mixed pulp obtained by mixing 60 parts of LBKP and 10 parts of NBKP to 30 parts of the used waste paper pulp for recording paper, AKD (Japan PMC Co., Ltd.) was used for 100 parts of pulp in terms of solid content as an internal sizing agent. Manufactured, SS-362) 0.3 part was added, and paper making was performed at 800 m / min with a twin wire paper machine to obtain a recording paper having a basis weight of 64 g / m ² . The obtained recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Comparative Example 3
The same procedure as in Example 1 was carried out except that the pulp fiber suspension was beaten at a temperature of 40 ° C., the beat speed was 800 rpm, and no cationic coagulant was added. Obtained. The obtained waste paper pulp for recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
Using mixed pulp obtained by mixing 60 parts of LBKP and 10 parts of NBKP to 30 parts of the used waste paper pulp for recording paper, AKD (Arakawa Chemical Co., Ltd.) is used for 100 parts of pulp in terms of solid content as an internal sizing agent. Ltd., SP287) was added 0.2 part performs paper at 800 m / min at a twin-wire paper machine, basis weight was obtained recording paper 64 g / ^{m 2.} The obtained recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Comparative Example 4
Except that the temperature during the beating treatment of the pulp fiber suspension was 45 ° C., the beating speed was 3500 rpm, and the cationic coagulant was not added, the same operation as in Example 1 was performed, and the waste paper pulp for recording paper was Obtained. The obtained waste paper pulp for recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.
Using mixed pulp obtained by mixing 40 parts of LBKP and 10 parts of NBKP to 50 parts of the used waste paper pulp for recording paper, AKD (Arakawa Chemical Co., Ltd.) is used for 100 parts of pulp in terms of solid content as an internal sizing agent. Ltd., SP287) was added 0.2 part performs paper at 800 m / min at a twin-wire paper machine, basis weight was obtained recording paper 64 g / ^{m 2.} The obtained recording paper was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

As apparent from Table 1, when recording paper was produced using the waste paper pulp for recording paper obtained in Examples 1 to 5, the wet end operability was stable and the formation evaluation was good. . That is, recording paper with uniform quality can be obtained by using the waste paper pulp for recording paper obtained in Examples 1 to 5.

Claims (4)

A disaggregation process for disaggregating unselected waste paper into a pulp fiber suspension;
A coarse selection step of removing impurities from the pulp fiber suspension;
A flotation step of removing ink and contaminants from the pulp fiber suspension from which the contaminants have been removed by flotation; and beating the pulp fibers contained in the pulp fiber suspension from which the ink and contaminants have been removed; A method for producing used paper pulp for recording paper, comprising a step of setting the mean fiber length of the pulp fibers to 0.70 mm to 1.00 mm. The method for producing waste paper pulp for recording paper according to claim 1, further comprising a step of adding a cationic coagulant to the pulp fiber suspension before beating the pulp fiber suspension. A recording paper produced by papermaking a pulp raw material containing waste paper pulp for recording paper obtained by the method for producing waste paper pulp for recording paper according to claim 1 or 2,
A recording sheet in which the recording sheet is divided into two equally or substantially uniformly in the Z-axis direction, and the difference in the mean fiber length between the divided front and back surfaces is 0.2 mm or less. The recording paper according to claim 3, wherein the surface is coated with a coating liquid.