JPH10121396A - Production of paper or paper board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain paper or paper board having high paper strength by adding a water-dispersible (meth)acrylamide-based polymer to a papermaking system containing a large amount of anionic contaminant. SOLUTION: A paper-strengthening agent composed of a water-dispersible (meth)acrylamide-based polymer is produced by polymerizing (meth)acrylamide with 0.1-10mol% of a monomer expressed by the formula (X is H, a 1-4C hydrocarbon group or an alkali metal atom) and containing phosphoric acid group such as mono(2-methacryloyloxyethyl) acid phosphate and further a cationic monomer such as dimethylaminopropyl (meth)acrylamide as constituent components. The paper-strengthening agent is added to a pulp slurry containing anionic contaminants composed of inorganic materials such as sulfate ion and chlorine ion at an inorganic anion concentration of 500-10,000ppm and/or an organic material such as a resin acid and lignin in an amount of 10-5,000ppm in terms of the anionic organic material concentration or 10-2,000 micro- equivalent/L in terms of cation requirement and a paper or paper board is produced from the pulp slurry compounded with the paper-strengthening agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing paper or paperboard. More specifically, the present invention relates to a method for producing paper or paperboard having excellent paper strength even in a papermaking system having a large amount of anionic impurities.

[0002]

2. Description of the Related Art In recent years, the situation of supply of raw wood, which is a raw material for paper, has been deteriorating, and an increase in the usage ratio of used paper has become an important issue. In addition, as a part of environmental measures, the closed process in the paper or paperboard manufacturing process has become unavoidable, and accompanying this, papermaking conditions such as a decrease in water quality and an increase in water temperature have become increasingly worse. In particular, the amount of used magazine waste paper and the like has increased, and as a result, a large amount of anion impurities have been present in the papermaking system.

[0003] Conventionally, anionic, cationic or amphoteric acrylamide-based polymers have been widely used as a paper-strength enhancer in such papermaking processes of paper or paperboard. However, due to the increase in the proportion of waste paper and the closure of wastewater, a large amount of anionic contaminants are present in the papermaking system, and as a result, the fixability of the paper strength enhancer to pulp is reduced, and the effect as a paper strength enhancer is reduced. It has not been able to express enough. That is, in the acrylamide-based polymer paper strength enhancer having ionicity, when a large amount of anionic impurities is present, the fixability to pulp is reduced, and the desired paper strength enhancement effect is not obtained.

[0004]

SUMMARY OF THE INVENTION The present invention provides a method for producing paper or paperboard having good fixation to pulp and excellent paper strength even in a papermaking system containing a large amount of anionic impurities. The purpose is to do.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems of the prior art, and as a result, as a paper strength enhancer, a (meth) acrylamide containing a specific phosphate group is used. By using a water-dispersible polymer, it was found that even a papermaking system containing a large amount of anionic impurities can produce paper or paperboard having excellent paper strength, and to complete the present invention. Reached.

That is, the present invention provides an anionic contaminant,
When an inorganic substance is contained as an anionic contaminant, the inorganic anion concentration is 50 ppm to 10000 ppm and / or when an organic substance is contained, the anionic organic concentration is 10 ppm to 5000 ppm or the cation requirement is 10 microequivalents / liter to 2000. In a pulp slurry containing microequivalents / liter, a general formula (1) is used as a paper strength agent:

[0007]

Embedded image

(Wherein, Xs are the same or different and each represents a hydrogen atom, a hydrocarbon group having 1 to 4 carbon atoms or an alkali metal atom). The present invention relates to a method for producing paper or paperboard, wherein papermaking is performed after adding a dispersible polymer.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The (meth) acrylamide-based water-dispersible polymer having a phosphate group represented by the general formula (1) of the present invention is obtained by polymerizing (meth) acrylamide. The method of introducing the phosphate group is not particularly limited as long as the polymer is a water-dispersible polymer and contains the phosphate group in the water-dispersible polymer.

[0010] Such a (meth) acrylamide-based water-dispersible polymer containing a phosphate group is, for example, (meth)
It is obtained by copolymerizing acrylamide and a monomer containing a phosphoric acid group represented by the general formula (1) as main components.

In the present invention, (meth) acrylamide means acrylamide or methacrylamide (hereinafter, the same meaning as (meth)). These can be used alone or in combination, but from the viewpoint of economy. Acrylamide is preferably used alone.

Specific examples of the phosphoric acid group-containing monomer represented by the general formula (1) include, for example, polyethylene glycol (meth) acrylate phosphate, 2-((diethoxyphosphinyl) oxy) Ethyl (meth) acrylate, bis ((meth) acryloyloxyethyl) hydrogen phosphate, mono (2- (meth) acryloyloxyethyl) acid phosphate, diphenyl-2- (meth) acryloyloxyethyl phosphate, 2-hydroxyethyl Examples thereof include (meth) acryloylphosphonic acid, 2- (meth) acrylamido-2-methylpropanephosphonic acid, and alkali metal salts thereof.

When the (meth) acrylamide and the phosphoric acid group-containing monomer represented by the general formula (1) are copolymerized as constituents, the amount of each monomer used is usually ( 9) meth) acrylamide
It is about 0 to 99.9 mol%, preferably about 92 to 99.5 mol%, while the phosphate group-containing monomer is 0.1 to 0.1 mol%.
About 10 to 10 mol%, preferably 0.5 to 8 mol%.

The (meth) acrylamide-based water-dispersible polymer having a phosphoric acid group according to the present invention may be any of the above (meth)
In addition to acrylamide and the phosphoric acid group-containing monomer represented by the general formula (1), an anionic property excluding a cationic monomer and / or a phosphoric acid group-containing monomer represented by the general formula (1) Includes those obtained by copolymerizing monomers as constituents.

As the cationic monomer, for example,
Salts of inorganic or organic acids such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, or the tertiary amino group-containing vinyl monomer Examples include vinyl monomers containing a quaternary ammonium salt obtained by a reaction with a quaternizing agent such as methyl chloride, benzyl chloride, dimethyl sulfate, and epichlorohydrin.

Examples of the anionic monomer other than the monomer having a phosphate group represented by the general formula (1) include monocarboxylic acids such as (meth) acrylic acid and crotonic acid; maleic acid and fumaric acid. Dicarboxylic acids such as acid, itaconic acid, muconic acid and citraconic acid; vinyl sulfonic acid, styrene sulfonic acid, methallyl sulfonic acid, 2-
Organic sulfonic acids such as acrylamide-2-methylpropanesulfonic acid; and sodium salts and potassium salts of these various organic acids.

When using an anionic monomer other than a cationic monomer and / or a monomer having a phosphate group represented by the above general formula (1), the amount of each monomer used is based on the total molar sum of the monomers. It is as follows.
That is, (meth) acrylamide is usually 80 to 9
It is about 9.8 mol%, preferably about 80 to 99.4 mol%. If it is less than 80 mol%, it is difficult to have a sufficient paper strength effect. On the other hand, the phosphate group-containing monomer is 0.1 to
It is about 10 mol%, preferably 0.5 to 8 mol%.
When the cationic monomer is used, the amount of the ionic monomer is about 0.1 to 10 mol%, preferably 0.2 to 8 mol%, and is represented by the general formula (1). When an anionic monomer other than a phosphoric acid group-containing monomer is used, the sum of the anionic monomer and the phosphoric acid group-containing monomer represented by the general formula (1) is 0.1 to 10 Mol%, preferably 0.2 to 8 mol%.

Furthermore, the (meth) acrylamide-based water-dispersible polymer of the present invention can be copolymerized with a crosslinkable monomer or another monomer as a constituent component within a range that does not adversely affect the performance, if necessary.

Examples of the crosslinking monomer include bifunctional monomers such as ethylene glycol di (meth) acrylate, diallylamine and N-methylolacrylamide, trifunctional monomers such as triallyl isocyanate and N, N-diallylacrylamide, and tetraallyloxy. Examples include tetrafunctional monomers such as ethane, and vinyl polymers having a chain transfer substituent such as allyl (meth) acrylate, diethylene glycol mono (meth) acrylate, and dimethylacrylamide. When a crosslinkable monomer is used, its amount is usually about 5 mol% or less, preferably 2 mol% or less, based on the total mol of the monomer. If it exceeds 5 mol%, the obtained copolymer becomes gel-like, which is not preferable.

Other monomers include, for example, t
N-substituted (meth) acrylamides such as octylacrylamide, (meth) acrylic acid, esters of anionic monomers such as maleic acid and alcohol, styrene,
α-methylstyrene, vinyltoluene, acrylonitrile, methylvinylether, isopropylacrylamide, vinyl acetate, α-olefin and the like. When other monomers are used, the amount used is about 20 mol% or less based on the total mol of the monomers, and (meth)
Instead of acrylamide, the amount of (meth) acrylamide used is reduced. If it exceeds 20 mol%, the proportion of (meth) acrylamide becomes small, and it is difficult to obtain a paper having a sufficient paper strength effect.

As the method for copolymerizing the above-mentioned monomer to obtain the (meth) acrylamide-based water-dispersible polymer of the present invention, various conventionally known methods can be adopted. For example, the above-described monomers and water are charged into a predetermined reaction vessel, and potassium persulfate, a persulfate such as ammonium persulfate, or a redox polymerization initiator in the form of a combination thereof with a reducing agent such as sodium bisulfite. The (meth) acrylamide-based water-dispersible polymer of the present invention can be obtained by adding a usual radical polymerization initiator and heating the mixture under stirring.

The weight average molecular weight of the obtained (meth) acrylamide-based water-dispersible polymer is usually from 100,000 to 1,000.
The viscosity is about 30,000 cps (25 ° C.) or less, preferably about 100 to 20,000 cps (25 ° C.) or less, when converted to a solid concentration of 10% by weight.

According to the method for producing paper or paperboard of the present invention, when an anionic contaminant is contained as an anionic contaminant and contains an inorganic substance, the inorganic anion concentration is 50 ppm to 1 ppm.
0000 ppm and / or 10 ppm to 5000 p as anionic organic concentration when containing an organic substance.
10 microequivalents / pm or cation requirement
The method further comprises adding the (meth) acrylamide-based water-dispersible polymer as a paper strength enhancer to a pulp slurry containing from 1 to 2000 microequivalents / liter, and then making the paper. Adopts the same conditions as general paper or paperboard manufacturing methods, except that it contains impurities and uses the specific ionic (meth) acrylamide-based water-dispersible polymer as a paper strength agent. it can.

That is, the paper strength enhancer is usually added at a usage ratio of about 0.1 to 1% by weight (solid content) based on the pulp solid content. The timing of adding the paper strength enhancer can be appropriately set, and the pH of the papermaking system can be applied over a wide range from an acidic range to an alkaline range. Further, the type of pulp and the type of papermaking white water only need to be appropriately determined according to the papermaking conditions, and a sizing agent, a fixing agent, a filler and the like can be appropriately compounded and added.

The anionic impurities in the pulp slurry are as follows:
Sulfate ions, chlorine ions, and the like can be given as inorganic substances.
Organic substances include resin acids, lignins, fatty acids, defoamers,
Surfactants and their colloidal substances can be mentioned. The anion contaminants also include salts of the inorganic or organic substances, such as sodium, potassium, calcium, and magnesium salts.

When the pulp slurry contains an inorganic substance as an anion contaminant as described above, the content of the inorganic substance is represented by an inorganic anion concentration. The inorganic anion concentration is a value measured by ion chromatography or a pocket water quality meter manufactured by LASA.

When the pulp slurry contains an organic substance as an anionic contaminant, the content of the organic substance is expressed by an anionic organic concentration or a cation requirement. The anionic organic component concentration is a value measured by ion chromatography or gel permeation chromatography. The amount of required cation was determined by dropping poly (diallyldimethylammonium chloride) into a filtrate obtained by filtering a pulp slurry through a filter paper (No. 5A).
It is a value obtained from the amount of poly (diallyldimethylammonium chloride) required until the potential of the filtrate becomes zero by a streaming potentiometer (PCD02). Usually, the measurement of the organic matter content in the pulp slurry based on the required amount of cation is used when the organic matter is a high molecular weight substance such as lignin or colloidal substance, and it is difficult to measure the organic matter concentration.

[0028]

According to the present invention, it is possible to provide a paper or paperboard having a paper strength such as specific burst strength, tear length, surface strength, etc. even in a papermaking system in which a large amount of anionic impurities are present. .

[0029]

The present invention will now be described more specifically with reference to examples and comparative examples. All parts and percentages are based on weight.

Production Example 1 500 parts of ion-exchanged water was charged into a flask equipped with a stirrer, a dropping funnel (A), a dropping funnel (B), a thermometer, a reflux condenser, and a nitrogen gas inlet pipe. On the other hand, the dropping funnel (A) contains 170 parts of acrylamide and 2 parts of ion-exchanged water.
30 parts and mono (2-methacryloyloxyethyl)
Acid phosphate (14 parts) and a dropping funnel (B) were charged with ammonium persulfate (0.21 part) and ion exchange water (100 parts) as a polymerization initiator. After removing oxygen in all the reaction systems through nitrogen gas, the inside of the reaction system is heated to 80 ° C. with stirring, and from 80 ° C., the entire amount is simultaneously discharged from the dropping funnel (A) and the dropping funnel (B). It was added dropwise over 2 hours. Then, ion-exchanged water was added to obtain an aqueous dispersion of an acrylamide polymer having a solid content of 10.4% and a viscosity of 7,300 cps.

Production Example 2 In Preparation Example 1, what was charged into the dropping funnel (A) was replaced with 159 parts of acrylamide, 230 parts of ion-exchanged water,
15.6 parts of dimethylaminopropylacrylamide, 8
The same operation as in Production Example 1 was carried out except that 4.5 parts of 0% acrylic acid and 14 parts of mono (2-methacryloyloxyethyl) acid phosphate were used, and the solid content was 10.4%.
%, And an aqueous dispersion of an acrylamide polymer having a viscosity of 8500 cps was obtained.

Production Examples 3 to 8 Same as Production Example 1, except that at least one of the types of the monomer components and the amounts used (composition ratio: mol%) was changed as shown in Table 1. Was carried out to obtain an aqueous dispersion of an acrylamide polymer. Table 2 shows the property values of the obtained aqueous dispersions.

[0033]

[Table 1]

In Table 1, AM: acrylamide, PM: mono (2-methacryloyloxyethyl) acid phosphate, AA: acrylic acid, DMAPAA: dimethylaminopropyl acrylamide, DM: dimethylaminoethyl methacrylate, DMAA: dimethylacrylamide Is shown.

[0035]

[Table 2]

Reference Example BKP was beaten with a Niagara-type beater to obtain 550 m of Canadian Standard Freeness (CSF).
After adding sodium carbonate as a pH adjuster to the pulp adjusted to 1 l, a sulfate band was further added to the pulp by 0.5%.
Then, the aqueous dispersion of each acrylamide polymer obtained in each of the production examples shown in Table 3 was added as a paper strength enhancer to 0.5% with respect to pulp, stirred and uniformly mixed. The resulting pulp slurry (pH 6.5) was diluted to 0.5%,
The paper was made with a tappy sheet machine so as to have a basis weight of 100 g / m ^2, and press-dewatered at 5 kg / m ² for 2 minutes. Next, it is dried at 100 ° C. for 4 minutes in a rotary dryer, and then dried at 20 ° C.
65% R. H. For 24 hours.

Examples 1 and 2 and Comparative Examples 1 and 2 BKP was beaten with a Niagara-type beater to obtain 550 m of Canadian Standard Freeness (CSF).
After adding sodium carbonate as a pH adjuster to the pulp adjusted to 1 l, sodium sulfate was added to the pulp slurry so that the amount of sulfate ions became a predetermined concentration shown in Table 4 or Table 5, and a sulfate band was further added. The pulp 0.5
% Of the acrylamide-based polymer obtained in each of the above Production Examples shown in Table 4 or Table 5 as a paper strength enhancer with respect to pulp of 0.5%, stirred, and uniformly mixed. did. The obtained pulp slurry (pH 6.5) was added to 0.1%.
Diluted to 5% and weighed 100 with Tappi sheet machine
g / m ^2, and press dewatered at 5 kg / m ² for 2 minutes. Then, it is dried at 100 ° C. for 4 minutes in a rotary dryer, and dried at 20 ° C. and 65% R.C. H. For 24 hours.

Reference Examples, Examples 1-2 and Comparative Examples 1-2
Was measured for the fixing ratio (%) and the delamination strength (g / cm) of the paperboard. The results are shown in Tables 3-5.
Shown in

(Fixing rate) The nitrogen content of the obtained paper was measured, and the fixing rate to pulp was calculated. Fixing rate (%) = (B
-C) / Ax100. A: Nitrogen measurement value of the applied acrylamide-based water-dispersible polymer, B: Nitrogen measurement value of paper made by adding the acrylamide-based water-dispersible polymer, C: B
Measured value of nitrogen content of paper made by using the same pulp as above and without adding acrylamide-based water-dispersible polymer.

(Interlayer Delamination Strength of Paperboard) Tappi
No. It measured according to 19-77.

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

[Table 5]

Example 3 and Comparative Example 3 Paper was produced in the same manner as in Example 1 except that sodium chloride was added instead of sodium sulfate.

The fixing ratio (%) and the breaking length (km) of the papers obtained in Example 3 and Comparative Example 3 were measured.
Table 6 shows the results.

Breaking length: A method for testing the tensile strength of paper and paperboard based on JIS P8113.

[0047]

[Table 6]

Example 4 and Comparative Example 4 Paper was produced in the same manner as in Example 1 except that lauric acid was added instead of sodium sulfate.

The fixing ratio (%) and the breaking length (km) of the papers obtained in Example 4 and Comparative Example 4 were measured.
Table 7 shows the results.

[0050]

[Table 7]

Example 5 and Comparative Example 5 Paper was produced in the same manner as in Example 1 except that sodium ligninsulfonate was added instead of sodium sulfate.

The fixing ratio (%) and the breaking length (km) of the papers obtained in Example 5 and Comparative Example 5 were measured.
Table 8 shows the results.

[0053]

[Table 8]

Example 6 and Comparative Example 6 A cardboard waste paper and a magazine waste paper were mixed at a weight ratio of 1: 1.
Beat it with a Niagara beater, Canadian
After adding 2% of the sulfuric acid band to the pulp adjusted to the standard freeness (CSF) of 420 ml, the aqueous dispersion of each acrylamide polymer obtained in each of the above production examples shown in Table 7 was strengthened with paper strength. As an agent, 0.5% of pulp was added, stirred, and uniformly mixed. The obtained pulp slurry (pH 5.6, calcium ion concentration 280 ppm) was diluted to 0.5%, and the basis weight was 1 using a tappi sheet machine.
Paper was made to 60 g / m ² and press dewatered at 5 kg / m ² for 2 minutes. Subsequently, it is dried at 110 ° C. for 4 minutes in a rotary dryer, and dried at 20 ° C. and 65% R.C. H. For 24 hours.

The specific burst strengths (kPa) of the papers obtained in Example 6 and Comparative Example 6 were measured. Table 9 shows the results.

Specific burst strength: A method for testing the burst strength of paper and paperboard using a Mullen low-pressure tester based on JIS P8112.

[0057]

[Table 9]

Example 7 and Comparative Example 7 BKP and coat broke were mixed in a weight ratio of 7: 3,
Beat it with a Niagara beater, Canadian
After adding 1.5% of a sulfuric acid band to the pulp adjusted to 450 ml of standard freeness (CSF), the aqueous dispersion of each acrylamide polymer obtained in each of the above production examples shown in Table 8 was applied to paper. 0.5% with respect to pulp was added as a force enhancer, stirred and uniformly mixed. The obtained pulp slurry (pH 6.6, calcium ion concentration 240 ppm)
Was diluted to 0.5%, paper was made with a tappy sheet machine so as to have a basis weight of 100 g / m ^2, and press-dewatered at 5 kg / m ² for 2 minutes. Then, it is dried at 100 ° C. for 4 minutes in a rotary dryer, and dried at 20 ° C. and 65% R.C. H. For 24 hours.

The surface strength (A) of the papers obtained in Example 7 and Comparative Example 7 was measured. Table 9 shows the results.

Surface strength: A method for testing the surface strength of paper and paperboard based on JIS P8129. By a method using a wax pick.

[0061]

[Table 10]

Claims (5)

[Claims] 1. When the anion contaminant contains an inorganic substance as an anion contaminant, the inorganic anion concentration is 5%.
0 ppm to 10000 ppm and / or 10 ppm as an anionic organic concentration when containing an organic substance.
A pulp slurry containing 〜5000 ppm or 10 microequivalents / liter as a cation requirement amount to 2,000 microequivalents / liter as a paper strength enhancer is represented by the general formula (1): Wherein X is the same or different and each represents a hydrogen atom, a hydrocarbon group having 1 to 4 carbon atoms, or an alkali metal atom. A method for producing paper or paperboard, comprising papermaking after adding molecules. 2. The (meth) acrylamide-based water-dispersible polymer having a phosphoric acid group comprises (meth) acrylamide and a compound represented by the general formula (1): (Wherein X is the same or different and each represents a hydrogen atom,
Represents a hydrocarbon group having 1 to 6 carbon atoms or an alkali metal atom. 2. The method for producing paper or paperboard according to claim 1, which is a water-dispersible polymer comprising a phosphate group-containing monomer represented by the formula (1) as a main component. 3. The method for producing paper or paperboard according to claim 2, wherein the (meth) acrylamide-based water-dispersible polymer containing a phosphate group is a water-dispersible polymer further containing a cationic monomer as a constituent. . 4. The (meth) acrylamide-based water-dispersible polymer containing a phosphate group further comprises a compound represented by the general formula (1): (Wherein X is the same or different and each represents a hydrogen atom,
Represents a hydrocarbon group having 1 to 6 carbon atoms or an alkali metal atom. 4. The method for producing paper or paperboard according to claim 2, which is a water-dispersible polymer comprising, as a constituent, an anionic monomer other than a monomer having a phosphate group represented by the formula (1). 5. A compound of the general formula (1): (Wherein X is the same or different and each represents a hydrogen atom,
Represents a hydrocarbon group having 1 to 6 carbon atoms or an alkali metal atom. The monomer having a phosphoric acid group represented by the formula (1) is used as a component of the (meth) acrylamide-based water-dispersible polymer.
The method for producing paper or paperboard according to claim 2, 3 or 4, comprising 1 to 10 mol%.