JP6340587B2 - Paperboard manufacturing method - Google Patents

Description

  The present invention relates to a method for producing paperboard, which enables efficient drying in a dryer part by improving drainage in a papermaking process, and can more efficiently produce paperboard such as corrugated board.

In the manufacture of paper, especially paperboards such as liners and core paper, there is a strong demand for improved drainage in the wire part and dryness in the dryer part from the viewpoint of improving production efficiency by increasing the papermaking speed in the papermaking process. ing.
In recent years, from the viewpoint of resource saving and energy saving, the ratio of waste paper used as a raw material for papermaking has increased, and with the increase in the ratio of broke pulp (waste paper) and the closure of white water, it has been accumulated in a circulating manner. The ratio of (anion trash) and fine fibers in papermaking raw materials has increased, yield and drainage have been reduced, and pitch troubles have frequently occurred.

Since anion trash consumes a yield improver and a drainage improver, an inorganic coagulant such as aluminum sulfate or polyaluminum chloride has been conventionally used as an anion trash catcher.
Aluminum sulfate has been used as a drainage improver, but this is insufficient, so polyethyleneimine, polyacrylamide organic polymer, cationized starch, etc. are used alone, or aluminum sulfate Often used in combination. JP-A-9-279498 (Patent Document 1) proposes the combined use of an acrylic water-soluble cationic copolymer and colloidal silica for the purpose of improving drainage.

  On the other hand, the applicant of the present application described in Japanese Patent No. 4143750 (Patent Document 2) and Japanese Patent No. 4825604 (Patent Document 3) uses a polydiallyldimethylammonium salt having a specific molecular weight and an inorganic aluminum compound in combination. A pitch failure prevention method is proposed.

Japanese Patent Laid-Open No. 9-279498 Japanese Patent No. 4143750 Japanese Patent No. 4825604

However, each of the additives used in the above prior art has problems.
Inorganic coagulants can manifest scale and corrosion problems as their usage increases.
In addition, polyethyleneimine has problems such as high addition costs and water foaming.
In addition, polyacrylamide-based cationic polymers that are frequently used as organic polymer polymers have many types of linear high-molecular weights mainly used to improve the yield of papermaking raw materials with wires, improving the yield. Even so, excessive moisture may be taken into the floc formed by the polymer, and the drainage and water squeezability may be reduced.
In addition, colloidal silica has a low concentration of active ingredients, which increases transportation costs, and there is a concern about the generation of silica scale at the addition point.

  The present invention provides a paperboard manufacturing method that enables efficient drying in a dryer part by improving the drainage in the papermaking process, and can more efficiently manufacture paperboard such as corrugated cardboard. Let it be an issue.

  The inventors of the present invention have added an aqueous solution of hypochlorite and an aqueous solution of inorganic ammonium salt or aqueous ammonia in the papermaking process water before being filtered by the wire when adding the aluminum ion supply compound to produce paperboard. The coexistence of the reaction mixture obtained by mixing with the aluminum ion supply compound so as to have a specific concentration significantly improves the drainage in the paper making process, thereby enabling efficient drying in the dryer part. As a result, the present inventors have completed the present invention.

It is well known that a bactericidal effect can be obtained by adding a reaction mixture obtained by mixing an aqueous solution of hypochlorite and an aqueous solution of inorganic ammonium salt to papermaking process water (for example, Japanese Patent No. 4288866). And Japanese Patent No. 4914146).
However, by allowing the above reaction mixture to coexist with the aluminum ion supply compound so as to have a specific concentration as residual chlorine in the papermaking process water before being filtered by the wire, the drainage improvement inherent in the aluminum ion supply compound is improved. It is a surprising fact that the effect is significantly enhanced.

Thus, according to the present invention, when manufacturing the plate sheet, the paper making process water before it is filtered by a wire, and (a) an aqueous solution of an aqueous solution and (b) inorganic ammonium salts hypochlorite or aqueous ammonia The reaction mixture obtained by mixing the effective chlorine in the aqueous solution of hypochlorite and the aqueous solution of inorganic ammonium salt or nitrogen in the aqueous ammonia to have a molar ratio of 1: 1 to 1: 2 as the residual chlorine concentration such that the 0.3 and 30 mg / L, the manufacturing method of paperboard, characterized in that for improving the freeness coexist with a Rumi ion supply compound.

According to the board manufacturing method of the present invention, by improving the drainage in the paper making process, it is possible to efficiently dry the dryer part, and more economically to manufacture board such as corrugated board. A manufacturing method can be provided.
Moreover, according to the board | substrate manufacturing method of this invention, the turbidity of filtrate becomes very clear, and the effect that the pitch trouble in a post process reduces can also be anticipated.

The board manufacturing method of the present invention has at least one of the following requirements:
(1) The addition amount of the aluminum ion supply compound is 1.0 to 8.0 kg as aluminum ions per ton of absolutely dry pulp.
(2) (a) component is an aqueous solution of sodium hypochlorite, potassium hypochlorite or calcium hypochlorite hypochlorite, (b) component is ammonium chloride, ammonium bromide, Ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium sulfate or ammonium nitrate aqueous solution or aqueous ammonia.
(3) the aluminum supply compound is aluminum sulfate, aluminum nitrate, polyaluminum chloride or polyhydroxyaluminum chloride; and (4) an organic polymer as a yield improver or drainage improver in the papermaking process water. When the organic polymer is further added to satisfy the coexistence of the organic polymer with the aluminum supply compound and the reaction mixture, the above effect is further exhibited.

6 is a flowchart showing the procedure of a test method of Test Example 1. FIG.

The paperboard manufacturing method of the present invention is a pulping process in which fibers are disaggregated and beaten from a pulp raw material containing waste paper to obtain a pulping process water, and a papermaking chemical is added to the pulping process water thus obtained. A papermaking process for making a paperboard by making the obtained pulp raw material, a drying process for drying the obtained wet paper, and a recovery process for recovering white water from the papermaking system and reusing it as a diluent. A method for producing paperboard,
In the production of paperboard by adding an aluminum ion supply compound, (a) an aqueous solution of hypochlorite and (b) an aqueous solution of inorganic ammonium salt or aqueous ammonia before being filtered by the wire. The reaction mixture obtained by mixing the effective chlorine in the aqueous hypochlorite solution and the aqueous solution of the inorganic ammonium salt or nitrogen in the ammonia water so as to have a molar ratio of 1: 1 to 1: 2 The drainage is improved by coexisting with the aluminum ion supply compound so that the chlorine concentration is 0.3 to 30 mg / L.

The drainage improvement effect of the present invention can be confirmed, for example, by measuring the dynamic drainage (g) of the papermaking process water by a known method as described in Examples.
In the method for producing paperboard of the present invention, the coexistence of the reaction mixture of the component (a) and the component (b) and the aluminum ion supply compound makes the dynamic drainage of the papermaking process water the conventional aluminum ion. Compared to the case of adding the feed compound alone, it is improved about 30 to 60%.

The turbidity reducing effect of the present invention can be confirmed, for example, by measuring the turbidity (NTU) of papermaking process water by a known method as described in Examples.
In the method for producing paperboard of the present invention, the turbidity of papermaking process water can be obtained by using a conventional mixture of the aluminum ion supply compound alone by coexisting the reaction mixture of the components (a) and (b) and the aluminum ion supply compound. 10 to 20% lower than the case of addition.

In the paperboard manufacturing method of the present invention, it is important that the aluminum ion supply compound and the above-mentioned reaction mixture at a specific concentration coexist in the papermaking process water before being filtered by the wire, that is, before papermaking. The order of addition, that is, the addition location is not particularly limited.
Examples of the place where the aluminum ion supply compound is added include a mixing chest, a machine chest, a seed box, and an inlet.
Examples of the addition location of the reaction mixture include a white water silo, a recovery tank, a mixing chest, a machine chest, a seed box, and an inlet.

(Aluminum ion supply compound)
The aluminum ion supply compound is not particularly limited as long as it does not inhibit the effect of the present invention, and examples include aluminum sulfate, aluminum nitrate, polyaluminum chloride, polyhydroxyaluminum chloride, alum and the like. Among these, aluminum sulfate, aluminum nitrate, Polyaluminum chloride and polyhydroxyaluminum chloride are preferred, and aluminum sulfate and aluminum nitrate are particularly preferred from an economical viewpoint.
The aluminum ion supply compound can be used in the form of a commercially available aqueous solution as it is, in a form in which the aqueous solution is appropriately diluted with water, or in a form in which a commercially available compound is appropriately dissolved in water.

The addition amount of the aluminum ion supply compound varies depending on the place of addition, but is preferably 1.0 to 8.0 kg / ton as aluminum ions per ton of absolutely dry pulp.
If the addition amount of the aluminum ion supply compound is less than 1.0 kg as aluminum ions per ton of absolutely dry pulp, the expected effect may not be exhibited. On the other hand, if the added amount of the aluminum ion supply compound exceeds 8.0 kg as aluminum ions per ton of absolutely dry pulp, an effect commensurate with economic loss may not be exhibited.
A more preferable addition amount of the aluminum ion supply compound is 3.0 to 7.0 kg as aluminum ions per ton of absolutely dry pulp.

(Reaction mixture)
The reaction mixture comprises (a) an aqueous solution of hypochlorite and (b) an aqueous solution of inorganic ammonium salt or aqueous ammonia, an effective chlorine in aqueous solution of hypochlorite and an aqueous solution of inorganic ammonium salt or aqueous ammonia. It is obtained by mixing so that the molar ratio with nitrogen is 1: 1 to 1: 2.

The component (a) is not particularly limited as long as the effect of the present invention is not impaired, and examples thereof include an aqueous solution of sodium hypochlorite, potassium hypochlorite and calcium hypochlorite. .
In the present invention, these aqueous solutions can be suitably used, and among these, a sodium hypochlorite aqueous solution is particularly preferable from an economical point of view.

The component (b) is not particularly limited as long as the effects of the present invention are not impaired. For example, ammonium chloride, ammonium bromide, ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium sulfate, and ammonium nitrate are water-soluble. An aqueous solution of an aqueous ammonium salt and aqueous ammonia are mentioned.
In the present invention, these aqueous solutions and aqueous ammonia can be suitably used. Among these, ammonium bromide aqueous solution, ammonium chloride aqueous solution and ammonium sulfate aqueous solution are particularly preferred from the economical viewpoint.

  The component (a) and the component (b) are used in the form of a commercially available aqueous solution as it is, in the form of appropriately diluting the aqueous solution with water, or in the form of appropriately dissolving a commercially available compound in water. be able to.

In the present invention, the component (a) has a concentration of 1000 to 9000 mg / L as the effective chlorine concentration, the component (b) has a concentration of 1000 to 9000 mg / L, and the effective chlorine in the component (a) and the component (b) It is preferable to use a reaction mixture obtained by mixing so that the molar ratio of nitrogen in the mixture is 1: 1 to 1: 2.
A more preferable reaction mixture has (a) component having a concentration of 1000 to 6000 mg / L as the residual chlorine concentration, (b) component having a concentration of 1000 to 6000 mg / L, and (a) the amount of residual chlorine in the component ( b) The molar ratio of nitrogen in the component is from 1: 1.1 to 1: 1.6.

The reaction mixture varies depending on the location of addition and the amount of chlorine required in the papermaking process water to be added, but in the papermaking process water before being filtered by the wire, the total residual chlorine concentration is 0.3 to 30 mg / L of aluminum ions. It only has to coexist with the supplied compound.
If the concentration of the reaction mixture is less than 0.3 mg / L as the total residual chlorine concentration, the expected effect may not be obtained. On the other hand, when the concentration of the reaction mixture exceeds 30 mg / L as the total residual chlorine concentration, an effect commensurate with economic loss may not be exhibited.
A preferable reaction mixture concentration is 0.5 to 30 mg / L as a total residual chlorine concentration, and a more preferable reaction mixture concentration is 1.0 to 20 mg / L.
In the present invention, “total residual chlorine” includes bound chlorine and free chlorine.
The “total residual chlorine concentration” can be measured by a known method such as the DPD method (JIS K0101) as described in Examples.

The reaction mixture may be added to the papermaking process water continuously or intermittently.
Moreover, in order to reduce the cost of the chemical | medical agent to be used, in the range which does not inhibit the effect of this invention, you may reduce the density | concentration of an aluminum ion supply compound and a reaction mixture, or you may make addition frequency intermittent.

(Organic polymer)
In the present invention, it is preferable to add an organic polymer as a yield improver or a drainage improver to the papermaking process water so that the organic polymer coexists with the aluminum supply compound and the reaction mixture. Thereby, the further improvement of the drainage in a papermaking process can be anticipated.

  Organic polymers include polyethyleneimine, polyvinylamine, acrylamide / aminomethylacrylamide copolymer salt (or quaternary ammonium salt), (meth) acryloyloxytrimethylammonium chloride homopolymer, acrylamide / (meth) Acryloyloxytrimethylammonium chloride copolymer, polydiallyldimethylammonium chloride, acrylamide / diallyldimethylammonium chloride copolymer, acrylic acid / diallyldimethylammonium chloride copolymer, cationic polymer such as cationized starch, polyacrylic acid soda, Polyacrylamide, polyacrylamide partial hydrolyzate, acrylamide / sodium acrylate copolymer, carboxymethylcellulose na Such as anionic polymers, such as potassium salts.

The weight average molecular weight of the organic polymer is preferably 5,000 to 50,000,000.
If the weight average molecular weight of the organic polymer is less than 5,000, the expected effect may not be obtained. On the other hand, if the weight average molecular weight of the organic polymer exceeds 50,000,000, excessive moisture may be taken into the floc formed by the polymer, and drainage and water squeezing may be reduced.
A more preferable organic high molecular weight polymer has a weight average molecular weight of 1,000,000 to 40,000,000.

The addition amount of the organic polymer is preferably 10 to 500 g, more preferably 10 to 50 g per ton of absolutely dry pulp.
The organic polymer can be used in a form in which a commercially available compound is appropriately dissolved in water.

  The present invention will be specifically described by the following test examples, but the present invention is not limited thereto.

Test example 1
Various chemicals were added to the pulp slurry, and their drainage improvement effect and turbidity reduction effect in the filtrate were evaluated.
For the test, the following commercially available compounds and separately prepared reaction mixtures were used.

(Aluminum supply compound)
Aluminum sulfate: 20% liquid aluminum sulfate was used.

(Reaction mixture)
Reaction mixture A:
Sodium hypochlorite solution (made by Kishida Chemical Co., Ltd., reagent) diluted 30 times with pure water (effective chlorine concentration 4800 mg / L) and 30% by weight ammonium sulfate aqueous solution of effective chlorine and nitrogen in the mixed solution The mixture was mixed so that the molar ratio was 1: 1.2 to obtain a reaction mixture A.
Reaction mixture B:
1.7% sodium hydroxide aqueous solution of 1 mol / L was added to a solution obtained by diluting a sodium hypochlorite solution (made by Kishida Chemical Co., Ltd., reagent) 30 times with pure water (effective chlorine concentration 4800 mg / L). Thereafter, a 35% by weight aqueous solution of ammonium bromide was mixed so that the molar ratio of effective chlorine to nitrogen in the mixed solution was 1: 1.2 to obtain a reaction mixture B.

(Organic polymer)
Polymer A: Cationic polymer comprising a copolymer of dimethylaminoethyl acrylate methyl chloride quaternary salt and acrylamide (manufactured by Nalco, weight average molecular weight: 30,000,000)
Polymer B: an anionic polymer comprising a copolymer of acrylamide and acrylate sodium salt (Nalco, average molecular weight: 5,000,000)
Polymer C: Polyacrylamide cationic polymer (manufactured by Nalco, average molecular weight: 5,000,000)

(Test method)
The pulp slurry collected from the pulp process at the paperboard factory was dehydrated to obtain a pulp cake. The pulp concentration of the pulp cake is measured in advance, tap water is added so that the pulp concentration is about 10 g / L (about 1% by weight), and the rotation speed is 300 rpm using a stirrer so that the pulp is uniformly dispersed. And stirred for 15 minutes to obtain a pulp slurry.
The obtained pulp slurry was divided into 15 L portions, and the reaction mixture was added so as to have the concentration shown in Table 1, and then allowed to stand at a liquid temperature of 36 ° C. for a certain period of time shown in Table 1. After standing, the total residual chlorine concentration (mg / L) in the pulp slurry (treated product) was measured by the DPD method (JIS K0101).
In addition, a comparison object is the pulp slurry which does not add a reaction mixture (unprocessed goods: Test numbers 1-4).

Based on the profile shown in FIG. 1, using an automatic retention / freeness freeness drainage meter (Spectris Co., Ltd., model: DFR05), each pulp slurry is mixed with the above-mentioned aluminum sulfate and organic polymer, in part From the above, the above reaction mixture was added, and the turbidity (NTU) in the filtrate immediately after the 90-second dynamic freeness (g) test was measured. The test start time of 0 seconds was set at the start of stirring of the drainage meter.
The above-described drainage meter sets a plurality of additive chemicals at the addition port, and has a profile as shown in FIG. 1, specifically, the additive agent addition amount and timing, the pulp slurry stirring speed and stirring time. By setting the discharge timing, various conditions of the papermaking process water in the actual machine can be reproduced, and the dynamic freeness and turbidity under these conditions can be measured.

Aluminum sulfate was added to all of test numbers 1 to 17 10 seconds after the start of the test. Test numbers 1 to 4 are comparative examples, and test numbers 5 to 17 are examples of the present invention.
5-17 except test number 7 are the examples which added the reaction mixture previously. Test No. 7 is an example in which the reaction mixture was added in 15 seconds after the test was started after the reaction mixture was not added in advance and left to stand for 60 minutes.
Test No. 8 is an example in which the reaction mixture was further added 15 seconds after the start of the test.
Test Nos. 6 to 11, 13, 15, and 17 are examples in which an organic polymer polymer of an arbitrary additive was further added within 20 seconds from the start of the test.

The used pulp slurry had the following physical property values (no addition of aluminum sulfate).
Pulp concentration: 7.96 g / L
Dynamic freeness (blank): 525 g
Turbidity (blank): 584 NTU
The difference from the above blank was determined from the measured values of dynamic freeness and turbidity.
For example, since the measured values of dynamic freeness and turbidity of test number 1 were 620 g and 184 NTU, respectively, the difference from each blank was determined by the following formula.
Dynamic freeness difference from blank = 620−525 = 95 (g)
Difference from turbidity blank = 184-584 = -400 (NTU)
In other words, the larger the difference from the dynamic freeness blank, the higher the dynamic freeness, the higher the freeness, and the lower the difference from the turbidity blank, the lower the turbidity. Means lower and clearer.

  The obtained results are shown in terms of the type of reaction mixture, the standing time (minutes), the total residual chlorine concentration after standing (mg / L), the amount of aluminum sulfate added (kg / ton), and the type of organic polymer. And the amount added (g / ton) are shown in Table 1. In Table 1, the addition amount of aluminum sulfate and the organic polymer is the addition amount with respect to the absolutely dry pulp.

From the results in Table 1, the following can be understood.
(1) When aluminum sulfate and a reaction mixture of a specific concentration coexist (test numbers 5, 12, 14 and 16), and when an organic polymer is used in combination (test numbers 6 to 11, 13, 15 and In 17), compared to the case of aluminum sulfate alone (Test No. 1), the dynamic freeness is remarkably improved and the turbidity in the filtrate is remarkably lowered (clarifies).
(2) When aluminum sulfate and a reaction mixture of a specific concentration are allowed to coexist (test numbers 5, 12, 14 and 16), aluminum sulfate and an organic cationic polymer are used in combination. Compared with the case (test number 2), the dynamic freeness is improved to the same level or more, and the turbidity in the filtrate is also reduced (clarifies).
Decreasing turbidity in the filtrate (clarification) means that the pitch component is dispersed and yielded on the paperboard, and the content of the pitch component in the filtrate is reduced. It is presumed that the pitch trouble will be reduced.

Claims (5)

In producing a plate sheet, the paper making process water before it is filtered by the wire, and (a) an aqueous solution of an aqueous solution and (b) inorganic ammonium salts hypochlorite or aqueous ammonia hypochlorite solution The reaction mixture obtained by mixing so that the molar ratio of available chlorine in the aqueous solution of inorganic ammonium salt or nitrogen in the aqueous ammonia is 1: 1 to 1: 2 is 0.3 to 0.3 as the total residual chlorine concentration. as it will be 30 mg / L, the manufacturing method of paperboard, characterized in that for improving the freeness coexist with a Rumi ion supplying compound.   The board | substrate manufacturing method of Claim 1 whose addition amount of the said aluminum ion supply compound is 1.0-8.0kg as aluminum ion per ton of absolutely dry pulp.   The component (a) is an aqueous solution of sodium hypochlorite, potassium hypochlorite or calcium hypochlorite hypochlorite, and the component (b) is ammonium chloride, ammonium bromide, phosphorus The method for producing paperboard according to claim 1 or 2, which is an aqueous solution of ammonium ammonium, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium sulfate or ammonium nitrate, or aqueous ammonia.   The method for producing paperboard according to any one of claims 1 to 3, wherein the aluminum supply compound is aluminum sulfate, aluminum nitrate, polyaluminum chloride or polyhydroxyaluminum chloride.   An organic polymer as a yield improver or a drainage improver is further added to the papermaking process water, and the organic polymer is allowed to coexist with the aluminum supply compound and the reaction mixture. 5. The method for producing paperboard according to any one of 4 above.

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