JPH0790796A - Neutral paper making process - Google Patents

Abstract

PURPOSE:To provide a process for making a neutral paper capable of efficiently improving the paper strength and getting a paper having excellent quality in the case of using a highly closed system of a paper-making white liquor to save the water to be used in the paper-making process or using a large amount of waste coated paper in a paper stock. CONSTITUTION:Water containing clear water recovered from paper-making white liquor is used for the defibration of waste coated paper and in a paper stock compounded with waste coated paper. In the above process for making a neutral paper, at least one kind of substance selected from ampholytic surfactant and cationic polymer is added after the addition of an anionic polymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a neutral papermaking method capable of efficiently increasing paper strength when highly closed paper water is used and a large amount of coated broke is used in the stock. Is.

[0002]

2. Description of the Related Art In recent years, in the papermaking process, in order to reduce the amount of water discharged to the outside of the system from the viewpoint of saving water, the amount of water circulating in the process is increased and the amount of fresh water to be replenished is reduced. The so-called papermaking process is being closed down.

[0003] Papermaking white water used in the papermaking process can generally be roughly classified into first circulating water and second circulating water. The 1st circulating water is mainly the backwater that comes out of the wire part and is used as it is for the dilution of the paper stock and sent to the headbox. However, the accumulated salt in the circulating water accumulates stains and paper strength in the papermaking system. There is a limit to the reuse of circulating water due to the reduced effectiveness of the chemicals and retention aids. The second circulating water is the over-water of the first circulating water, drainage from the press part, etc., and the stock material and the clear water are separated by a raw material recovery machine such as a saver, adca, or a poly disc filter, and the stock material is The clarified water that is reused in the papermaking system is used as shower water for the paper machine, water for disintegrating pulp and broke, and a part of it is discharged to the outside of the papermaking system.

The closed papermaking process increases the frequency of reuse of the first circulating water, reduces the discharge of the second circulating water to the outside of the papermaking system, and is contained in the stock newly supplied to the papermaking machine. To reduce the amount of fresh water. In particular, it is necessary to reduce the discharge of the second circulating water to the outside of the papermaking system.

Further, from the viewpoint of resource saving, it is desirable to increase the coating waste paper in the stock. The coated spoiled paper here means
Coated paper for printing, carbonless paper, which occurs in the paper mill
It is broke such as thermal paper.

[0006] Neutral papermaking can suppress the dissolved salts centering on aluminum ions in the system to a lower level than acidic papermaking, so that the whitening of papermaking can be easily closed. Further, even if the coated broke containing calcium carbonate is reused, the neutral papermaking causes less problems.

[0007] Since neutral papermaking does not use aluminum sulfate when the papermaking pH is near neutrality, a method using a specific amphoteric or cationic paper strengthening agent is disclosed in JP-A-57-128.
No. 293, JP-A-58-104299, etc.
Japanese Patent Publication No. 62-24560 discloses a method of using a coated broke in a paper stock in a neutral papermaking process and using a cationic paper strengthening agent. Further, Japanese Patent Laid-Open No. 4-333683 discloses a method of using a broke of information recording paper without passing through a used paper process.

[0008] In neutral papermaking, amphoteric polyacrylamide and cation are used as a method for improving the raw material yield on the wire in order to close the papermaking whitewater, which increases the reuse frequency of the papermaking whitewater and reduces the release outside the papermaking process. A method of using a polymer having a functional group and different from the above-mentioned polyacrylamide-based copolymer is disclosed in JP-A-5-78997, and in neutral papermaking, papermaking white water is clarified and a paper-strengthening agent or a step is added. In order to bring out the effect of the retention improver, a method of adding a cationizing agent to papermaking white water to specify the specific conductivity of the papermaking white water is disclosed in JP-A-2-80690. Further, Japanese Patent Publication No. 63-17958 discloses a method of adding a low molecular weight cationic agent before the addition of the cationic paper strengthening agent in order to block the anion component.

However, when water containing recovered clear water is used for disaggregation of stock such as coated broke and a neutral papermaking method containing a cationic paper strength enhancer is used, sufficient paper strength is obtained. It is not possible to obtain the enhancing effect.

[0010]

However, in the conventionally known method as described above in the neutral papermaking method, the amount of water used is saved, and a polymer having a cationic group as a cationizing agent is added to make a paper. In this case, when the water in the papermaking system is contaminated, it is necessary to add a large amount in order to obtain the effect of increasing the paper strength, so the electrical balance in the system is disrupted and the texture deteriorates, causing a deterioration in paper quality. The strength-enhancing effect cannot be further improved. This tendency is particularly remarkable when a large amount of coated broke is used.

The object of the present invention is to save the water used in the papermaking process and to use a large amount of coated broke,
At the same time, it is intended to provide a neutral papermaking method capable of obtaining a paper of good quality.

[0012]

Means for Solving the Problems The present invention provides a neutral papermaking method in which water containing recovered clear water from paper white water is used for disaggregation of coated broke and stock containing blended broke,
The neutral papermaking method is characterized by adding at least one selected from an amphoteric polymer and a cationic polymer after adding an anionic polymer.

[0013]

The present invention is a neutral papermaking method capable of enhancing the paper strength and simultaneously improving the quality of paper when a large amount of coated broke is used in the paper stock, and the papermaking white water is highly closed. Is.

When the coated broke is used as a stock, neutral papermaking is widely practiced in order to prevent decomposition of calcium carbonate contained in the coated broke. In the neutral papermaking method, the addition of a paper strength enhancer, a retention improver, etc. should be performed in the papermaking system.
In consideration of H and electric balance, a cationic polymer and an amphoteric polymer are used alone, or a dual polymer system in which a cationic polymer and an amphoteric polymer are added and then an anionic substance is added is widely used.

However, in these conventional neutral papermaking methods, white papermaking water is divided into paper stock and recovered clear water by a raw material recovery machine, and water containing the recovered clear water is disaggregated from coated stock such as uncoated paper. When used for papermaking by the neutral papermaking method, it is impossible to obtain a sufficient paper-strengthening effect.

When the amount of coated broke is increased in the stock in the papermaking process, the anionic component from the coated broke is increased, and it reacts with the cellulose in the pulp to exhibit an effect. The ingredients react and reduce their effectiveness. Therefore, a large amount of the paper strength additive is added, and the operability, quality and economical efficiency are deteriorated.

There is a method of adding a low molecular weight cationic agent before adding a cationic paper strength enhancer for blocking the above-mentioned anion component. However, water containing recovered clear water is used for coating uncoated paper etc. When the paper is used for the disintegration of paper stock and prepared by the neutral paper making method in which the cationic paper strengthening agent is added, a sufficient paper strengthening effect cannot be obtained. In other words, the effect cannot be fully exerted under the influence of the dissolved salts remaining in the recovered clear water and the unblocked anion components such as coated rubbed paper. Further, when the amount of the low molecular weight cationic agent added is increased, the papermaking system is likely to shift to the acidic side, and the amount of dissolved salts in the paper stock is increased to increase the amount of M such as alumina deposit.
/ C stains are caused, and the electrical balance in the papermaking system is lost, so that the workability is deteriorated and the paper strength increasing effect is not improved so much.

Further, when the amount of the paper strength enhancer having a cationic group is increased, the aggregation effect becomes stronger than the paper strength effect and the wire separation becomes worse, which makes the operation difficult.

According to the neutral papermaking method of the present invention, when the coated broke is disintegrated by using the water containing the recovered clear water, the disintegrated coated broke is added to the stock material first to have a high anionic content. The molecule is added, followed by the amphoteric polymer or the cationic polymer. This method keeps the papermaking system neutral,
The dissolved salts in the paper stock and the electrical balance in the system can be well maintained, the operability can be stabilized, and the paper strength enhancing effect can be improved.

That is, the anionic component in the paper stock is increased by first adding the anionic polymer substance, but since the polymer which is rich in the bondability with the pulp and has the paper strength enhancing effect is added, When an amphoteric polymer or a cationic polymer is added, pulp, an anionic polymer, and an amphoteric polymer or a cationic polymer are sufficiently bound to efficiently enhance the paper strength.

It should be noted that, while adding an anionic polymer and then an amphoteric polymer or a cationic polymer in order to block a minute anion component, a low content of aluminum sulfate, polyaluminum chloride, polyaluminum silicate sulfate, etc. Molecular cationic agent 0.05% to 0.5
% (Per pulp) can also be added.

In the present invention, the coated broke is 20% of the total stock.
%, Or if the recovered clarified water is less than 50% of the water used for disaggregation, the effects of the present invention may not be sufficiently obtained. It is a particularly excellent method when

The anionic polymer used in the present invention is specifically a side chain of a polymer such as monocarboxylic acid, dicarboxylic acid, sulfonic acid and the like, and starch, cellulose, polyacrylamide and the like having these salts added thereto. In particular, anionic polyacrylamide having a hydroxyl group or an amide group, which easily hydrogen-bonds with cellulose in pulp in the polymer chain, is desirable.

If the molecular weight of the anionic polyacrylamide exceeds 4,000,000 and is large, the cohesive effect is stronger than the paper strength enhancing effect, and the paper quality is deteriorated due to difficulty in operation in the wire part and deterioration of the formation. Further, if the molecular weight is less than 300,000, the effect of increasing the paper strength cannot be obtained due to the dissolved salts in the paper material and the fine substances that have a negative effect on the paper strength. Especially in the case of anionic low-molecular weight compounds and inorganic salts, it is difficult to obtain the desired effect. Therefore, in consideration of the compatibility with the amphoteric or cationic polymer added later, the molecular weight is 300,000 to 4,000,000,
More preferably, it is 300,000 to 1,000,000. Further, the addition amount is preferably 0.05% to 0.3% (per pulp).

Examples of the amphoteric or cationic polymer used in the present invention include cationized starch, polyamine polyamide epichlorohydrin, cationic polyacrylamide, amphoteric polyacrylamide and the like, and particularly cationic polyacrylamide and amphoteric polyacrylamide. desirable. The molecular weight of the amphoteric polymer or the cationic polymer is preferably 1,000,000 to 4,000,000, depending on the binding properties with the cellulose of the pulp and the anionic polymer substance added previously. From the viewpoint of effect and handling, paper pulp technology Association magazine, 46 (8), 28 (1992), JP-A-5-195
Those having a low-viscosity, branched or crosslinked structure as exemplified in JP-A No. 485 and JP-A No. 5-86597 are preferable. If the molecular weight of the amphoteric polyacrylamide or the cationic polyacrylamide is less than 1 million, it is difficult to exert the effect of enhancing the paper strength, and if the molecular weight exceeds 4 million, the aggregation becomes strong and the formation becomes poor, so that it becomes difficult to obtain good paper quality.

The amphoteric polyacrylamides and cationic polyacrylamides used in the present invention are copolymers of acrylamide and cationic vinyl monomers, polyacrylamides which are made cationic by Mannich reaction or Hoffmann decomposition. A region-stable copolymer of acrylamide and a cationic vinyl monomer is desirable. Further, the addition amount is preferably 0.3% to 1.0% (per pulp).

In the present invention, pulp, filler, sizing agent and various auxiliaries are added to the paper material in addition to the paper strengthening agent.

The pulp to be used is at least one selected from chemical pulp, mechanical pulp made from wood fibers and plant fibers such as hemp, or used paper pulp, synthetic pulp, inorganic fibers and the like obtained from them. It can be appropriately selected and used.

As the filler, commonly used fillers are used and are not particularly limited. For example, heavy calcium carbonate, light calcium carbonate, calcium sulfite, gypsum, talc, kaolin, clay, calcined kaolin, Inorganic pigments such as amorphous silica, deramikaolin, diatomaceous earth, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, polystyrene resin particles, urea formalin resin particles, micro hollow particles, etc. The organic pigments and the like are listed as examples, and the fillers and pigments contained in waste paper, broke and the like can also be recycled. Further, if necessary, two or more kinds of fillers can be appropriately combined and used.

In addition to pulp fiber and filler in the paper,
The internally used sizing agent or the like which has been conventionally used is appropriately selected and used as needed within a range that does not impair the intended effects of the present invention. For example, various compounds of various sizing agents (alkyl ketene dimer type, alkenyl succinic anhydride type, styrene-acrylic type, higher fatty acid type, petroleum resin type sizing agent, rosin type sizing agent, etc.) can be exemplified. Further, within a range that does not impair the desired effects of the present invention, papers after adding an amphoteric polymer or a cationic polymer of the present invention to an internal additive such as a retention improver or a drainage improver that has been conventionally used It is also possible to add it to the ingredients.

Further, dyes, optical brighteners, pH adjusters,
An internal additive for papermaking such as a defoaming agent, a pitch control agent and a slime control agent may be appropriately added depending on the application.

As the paper machine, a Fourdrinier paper machine, a twin wire paper machine, a cylinder paper machine, a Yankee paper machine, or the like can be appropriately used.

A size press treatment may be applied to the paper produced by the present invention. Size press liquids include starch, various modified starches, various water-soluble celluloses, various polyvinyl alcohols, various polyacrylamides, latex, alkyl ketene dimers, styrene-acrylic, olefin-maleic anhydride, and higher fatty acid surface sizes. Agents, waterproofing agents such as epoxy compounds, optical brighteners, defoamers, wetting agents, antistatic agents, various inorganic pigments, various organic pigments, dyes,
Starch particles and various additives can be added according to the purpose.

The application method of the size press liquid is not particularly limited, and for example, a commonly used size press device such as a two-roll or metering blade type size press, a bill blade size press, a gate roll size press, a calender, and the like. Air knife coater,
A commonly used coating device such as a roll coater, a pure blade coater, a rod blade coater, a short dwell coater, a gravure coater, a metalling bar coater, a curtain coater, a die coater, and a spray coater is appropriately used, and both sides or one side of the paper is used. Applied to.

In addition, the white papermaking paper is divided into a stock and a recovered clear water by a raw material recovery machine, and various kinds of water used when disintegrating the water containing the recovered clear water for pulp and coated stock such as broke A flocculant can also be appropriately used in the present invention.

The paper produced by the neutral papermaking method of the present invention is
Applicable to paper products of all grades and types.
For example, not only base paper for printing coated paper such as brochures, calendars, weekly magazines, gravure paper used as wrapping paper, art paper, coated paper, cast coated paper, slightly coated paper, but also pressure sensitive recording paper, Information paper such as thermosensitive recording paper, ink jet paper, photosensitive paper, sublimation transfer image receiving paper, adhesive paper, base paper such as processed paper used for lamination or vapor deposition, and various printing paper, newsprint paper, book paper, foam paper, PPC It is widely applicable to paper, OCR paper, paperboard, paper base paper, cardboard base paper and the like.

[0037]

EXAMPLES In order to clarify the effects of the present invention, examples will be described below, but the invention is not limited thereto. Parts and% in the examples mean parts by weight and% by weight, respectively.

Example 1 Pulp slurry 100 consisting of 70 parts of LBKP disintegrated using recovered clear water and beaten to 450 ml of CSF, and 30 parts of broke of coated printing paper disintegrated using recovered clear water
Part was diluted to a concentration of 3% with recovered clear water, 10 parts of heavy calcium carbonate was added, and then anionic polyacrylamide having a molecular weight of 350,000 (Polystron 11
7, Arakawa Chemical Industry Co., Ltd.) 0.1 part, aluminum sulfate 0.1 part, and a copolymer type amphoteric polyacrylamide having a molecular weight of 3,000,000 (Harmide EX-360, manufactured by Harima Chemicals Co., Ltd.) 0.5 part The paper stock was prepared by diluting the papermaking white water with the first circulating water. The obtained paper material was paper-made with a Fourdrinier paper machine to obtain 64 g / m ² of paper.

Example 2 LBK4 was prepared by adding 70 parts of LBKP to 30 parts in Example 1 and disintegrating using fresh water, and beating into 450 ml of CSF.
A paper was obtained in the same manner as in Example 1 except that 0 part was newly added and the broke of the coated printing paper was changed to the broke of the under-carbon paper.

Example 3 A paper was obtained in the same manner as in Example 1 except that fresh water was used instead of the recovered clear water for disaggregation of LBKP.

Example 4 A paper was obtained in the same manner as in Example 1 except that the addition of aluminum sulfate was stopped.

Example 5 In Example 1, recovered clear water was used for disaggregation to remove CS.
Paper was obtained in the same manner as in Example 1 except that 70 parts of LBKP beaten to 450 ml of F was changed to 30 parts, and 30 parts of broke of the coated printing paper disintegrated using the recovered clear water was changed to 70 parts.

Example 6 In Example 1, the recovered clear water was used for disaggregation to remove CS.
Paper was obtained in the same manner as in Example 1 except that 70 parts of LBKP beaten to 450 ml of F was changed to 85 parts, and 30 parts of broke of the coated printing paper disaggregated by using the recovered clear water was changed to 15 parts.

Example 7 The same as Example 1 except that the anionic polyacrylamide having a molecular weight of 350,000 was replaced with the anionic polyacrylamide having a molecular weight of 4 million (Arafix 504, manufactured by Arakawa Chemical Industry Co., Ltd.). Got the paper.

Example 8 In Example 1, a copolymer type amphoteric polyacrylamide having a molecular weight of 3,000,000 (Harmide EX-360, manufactured by Harima Chemicals) was used as a copolymer type amphoteric polyacrylamide having a molecular weight of 800,000 (Polystron 678, Arakawa). A paper was obtained in the same manner as in Example 1 except that it was changed to (Chemical Industry Co., Ltd.).

Example 9 In Example 1, a copolymer type amphoteric polyacrylamide having a molecular weight of 3,000,000 (Harmide EX-360, manufactured by Harima Kasei) was used as a cationic polyacrylamide having a molecular weight of 6,000,000 (Hydrocor 803, manufactured by Kyowa Sangyo Co., Ltd.). A paper was obtained in the same manner as in Example 1 except that the content was changed to ().

Example 10 In Example 1, anionic polyacrylamide having a molecular weight of 350,000 was converted into anionic polyacrylamide having a molecular weight of 2 million, and amphoteric polyacrylamide having a molecular weight of 3 million was amphoteric as a copolymer type having a molecular weight of 2 million. Paper was obtained in the same manner as in Example 1 except that polyacrylamide was used.

Example 11 In Example 1, the addition amount of the anionic polyacrylamide having a molecular weight of 350,000 was changed from 0.1 part to 0.04 part, and the addition amount of the copolymer type amphoteric polyacrylamide having a molecular weight of 3 million was changed to 0. Example 1 except that the amount was changed from 0.5 part to 0.25 part.
Paper was obtained in the same manner as in.

Example 12 In Example 1, the amount of anionic polyacrylamide having a molecular weight of 350,000 was changed from 0.1 part to 0.4 part, and a molecular weight of 3 was added.
A paper was obtained in the same manner as in Example 1 except that the addition amount of the copolymer type amphoteric polyacrylamide was changed from 0.5 parts to 1.1 parts.

Example 13 In Example 1, the anionic polyacrylamide having a molecular weight of 350,000 was replaced with carboxymethyl cellulose, and a copolymer type amphoteric polyacrylamide having a molecular weight of 3 million was replaced with polyamine polyamide epichlorohydrin (WS-57).
0, manufactured by Japan PMC Co., Ltd.), and paper was obtained in the same manner as in Example 1.

Comparative Example 1 A paper was obtained in the same manner as in Example 1 except that the addition of the anionic polyacrylamide having a molecular weight of 350,000 was stopped.

Comparative Example 2 A paper was obtained in the same manner as in Example 1 except that the addition of the copolymer type amphoteric polyacrylamide having a molecular weight of 3,000,000 was stopped.

Comparative Example 3 Regarding the disaggregation of broke of LBKP and coated printing paper in Example 1, paper was obtained in the same manner as in Example 1 except that fresh water was used instead of the recovered clear water.

Comparative Example 4 In Example 1, the anionic polyacrylamide having a molecular weight of 350,000, aluminum sulfate 0.1 part, and a copolymer type amphoteric polyacrylamide having a molecular weight of 3 million were added in the order of copolymer type amphoteric polymer having a molecular weight of 3 million. Paper was obtained in the same manner as in Example 1 except that polyacrylamide, aluminum sulfate, and anionic polyacrylamide having a molecular weight of 350,000 were changed in this order.

Comparative Example 5 A paper was obtained in the same manner as in Example 1 except that nonionic polyacrylamide was used instead of the anionic polyacrylamide.

Comparative Example 6 In Example 1, except that the amount of the copolymer type amphoteric polyacrylamide having a molecular weight of 3,000,000 was changed from 0.5 part to 1.5 parts, and the addition of the anionic polyacrylamide having a molecular weight of 350,000 was stopped. Was obtained in the same manner as in Example 1.

The 19 types of neutral paper stocks and the papers produced as described above were evaluated for stains, internal strength and formation by the following methods. The evaluation results are shown in Table 1.

(Evaluation Test of Stain) After adding various chemicals, a stock material diluted with the first circulating water of papermaking white water was filtered through a 100 mesh wire, and 100 kg of the filtrate was circulated for 1 hour.
It was poured on a stainless steel plate at a flow rate of 00 ml / min for 10 days. After washing with water, the degree of stain was visually evaluated according to the following evaluation criteria. ⊚: Excellent ○: Good Δ: Slightly soiled ×: A lot of soiled

(Measurement of Internal Strength) TAPPI UM 4
It measured based on 03.

(Measurement of formation) Formation measurement machine FMT-100
0A (manufactured by Nomura Trading Co., Ltd.). If the formation index is large, the formation is inferior.

[0061]

[Table 1]

[0062]

As is clear from the results of the examples, in the neutral papermaking method of the present invention, it is possible to achieve a high degree of closedness of white papermaking paper, and when a large amount of uncoated paper is used in the stock. In addition, excellent operability, paper-strengthening effect and paper with good texture were obtained.

Claims (4)

[Claims] 1. Water containing recovered clear water from papermaking white water,
In the neutral papermaking method used for disaggregation of coated broke and paper stock containing coated broke, at least one selected from amphoteric polymers or cationic polymers after addition of anionic polymer A neutral papermaking method characterized by adding. 2. The neutral papermaking method according to claim 1, wherein the coated broke has a pulp content of 20% or more with respect to the total stock pulp. 3. The neutral papermaking method according to claim 1, wherein the water contains 50% or more of recovered clear water. 4. The molecular weight of the anionic polymer is 300,000-40.
It is an anionic polyacrylamide having a molecular weight of 1,000,000 to 40, and is an amphoteric polymer or a cationic polymer.
The neutral papermaking method according to any one of claims 1 to 3, wherein the amount is 100,000 amphoteric polyacrylamide or cationic polyacrylamide.