JPH10259588A - Additive for papermaking and production of paper or paperboard - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an additive for papermaking capable of manifesting high improving effects on paper strength as a paper strengthening agent by compounding phosphate group-containing starches with a specific ionic poly(meth)acrylamide derivative and an inorganic salt. SOLUTION: This additive for papermaking is prepared by mixing 50-98wt.% urea phosphated starch with 50-2wt.% ionic poly(meth)acrylamide derivative obtained by copolymerizing (meth)acrylamide as a principal component with an anionic group-containing monomer such as acrylic acid and/or a cationic group-containing monomer such as an N,N'-dialkylaminoalkyl(meth)acrylamide in an amount of 1-30mol.% based on the total molar amount of the monomers and an inorganic salt such as sodium chloride or sodium sulfate in an amount of 1-2wt.% based on the sum of the solid weight of the two components. The resultant additive has 100-20,000cPs viscosity (at 25 deg.C) at 10wt.% concentration. The additive is internally added to a pulp slurry and then formed to produce a sheet of paper or paperboard.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a papermaking additive and a method for producing paper or paperboard. The papermaking additive of the present invention can be used as a drainage agent for papermaking, a paper strength enhancer, a filler retention agent, a size fixing agent, and the like. In particular, the papermaking additive of the present invention has a high paper strength improving effect as a paper strength enhancer.

[0002]

2. Description of the Related Art Conventionally, starches have been used as paper strength agents. In many cases, starches are gelatinized and added to the pulp slurry in the form of a sizing solution. However, the starch paste has poor storage stability, and causes a deterioration phenomenon called aging, which causes a problem that the paste is gelled or water is separated.
For this reason, not only the desired paper strength effect cannot be obtained, but also it is necessary to gelatinize the starch powder on site, resulting in a decrease in productivity and workability of the papermaking company.

[0003] In order to solve these problems, attempts have been made to improve the storage stability of the paste in the form of a paste by adding a surfactant to the starch paste. However, the one in which the storage stability of the starch paste solution is improved by such a method, the paper strength effect of starch inherently decreases,
There has not yet been found one that achieves both storage stability and maintenance of the paper strength effect. In addition, studies have been made on the graft polymerization of acrylamide to starch, but when the blending ratio of starch is high, it cannot be said that the storage stability of the starch paste solution and the paper strength effect are also compatible. , Has not yet solved the problem.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a papermaking additive which has a long-term storage stability in the state of a starch paste solution and which can maintain the excellent paper strength enhancing effect inherent to starch. The purpose was to.

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above problems, and as a result, mixed an ionic poly (meth) acrylamide derivative with a starch paste solution containing a phosphate group. In addition, they have found that a water-soluble or water-dispersible starch paste solution obtained by further adding an inorganic salt solves the above-mentioned problems, and have completed the present invention.

That is, the present invention provides (A) a starch containing a phosphate group, (B) an ionic poly (meth) acrylamide derivative, and a weight sum (solid content) of (A) and (B).
To a papermaking additive consisting of a mixed solution containing 1 to 20% by weight of (C) an inorganic salt, and further to a pulp slurry,
The present invention relates to a method for producing paper or paperboard, wherein papermaking is performed after the addition of the papermaking additive.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION (A) Starches containing a phosphate group include those originally containing a phosphate group, such as potato starch, or raw starch such as wheat, rice, corn, tapioca, and the like. Dextrin or urea phosphate modified starch such as oxidized starch into which a phosphate group is introduced can be used. In the present invention, among these (A) starches containing a phosphate group, the viscosity (viscosity measured immediately at 25 ° C. after cooling by gelatinizing to a concentration of 10% by weight) is 1%.
It is preferable to use one showing 00 cps or more from the viewpoint of paper strength enhancing effect. The use of a material having a viscosity of 20,000 cps or less is advantageous in terms of workability and the like when a mixture of (B) an ionic poly (meth) acrylamide derivative and (C) an inorganic salt is sent to a pulp slurry. Is preferred.

[0008] The (B) ionic poly (meth) acrylamide derivative is a polymer obtained by polymerizing (meth) acrylamide as a main component, and an anionic and / or cationic polymer is contained in the polymer. It refers to those containing an ionic group, and any of anionic poly (meth) acrylamide derivatives, cationic poly (meth) acrylamide derivatives or amphoteric poly (meth) acrylamide derivatives can be used. The content of the anionic group-containing monomer constituent unit and / or the cationic-containing monomer constituent unit in such a polymer is about 1 mol% or more based on the total molar amount of the monomers constituting the polymer. It is preferable to improve storage stability after mixing with (A) a starch containing a phosphate group. Further, in consideration of economy, it is preferable to set the content to about 30 mol% or less.

(Meth) acrylamide refers to acrylamide and / or methacrylamide, which can be used alone or in combination, but from the viewpoint of economy, acrylamide is preferably used alone.

The method for producing the anionic poly (meth) acrylamide derivative is not particularly limited. For example, a method of introducing an anionic group by a suitably selected modification method such as hydrolysis of poly (meth) acrylamide in an alkaline aqueous solution. Alternatively, a method of copolymerizing (meth) acrylamide with an anionic group-containing monomer can be employed. Specific examples of the anionic group-containing monomer include α, β such as monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, and dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, muconic acid and citraconic acid. -Unsaturated carboxylic acid; vinyl sulfonic acid, styrene sulfonic acid, methallyl sulfonic acid, 2-
Α, β-unsaturated sulfonic acids such as acrylamide-2-methylpropanesulfonic acid; polyethylene glycol (meth) acrylate phosphate, 2-((diethoxyphosphyl) oxy) ethyl (meth) acrylate, bis ((meth) acro Yloxyethyl) hydrogen phosphate, mono (2- (meth) acryloyloxyethyl) acid phosphate, diphenyl-
2- (meth) acryloyloxyethyl phosphate,
2-hydroxyethyl (meth) acroyl phosphonic acid,
Phosphoric acid group-containing monomers such as 2- (meth) acrylamide-2-methylpropanephosphonic acid; and alkali metal salts such as sodium salts and potassium salts thereof.

The method for producing the cationic poly (meth) acrylamide derivative is not particularly limited. For example, a method of introducing a cationic group into poly (meth) acrylamide by an appropriately selected modification method such as Mannich modification or Hoffman modification, or A method of copolymerizing (meth) acrylamide with a cationic group-containing monomer can be employed. Examples of the cationic group-containing monomer include N, N-dialkylaminoalkyl (meth) acrylamide and / or N, N
Tertiary amino group-containing monomers such as -dialkylaminoalkyl (meth) acrylate, and specific examples thereof include N, N-
Dimethylaminoethyl (meth) acrylate, N, N-
Diethylaminoethyl (meth) acrylate, N, N-
Dimethylaminopropyl (meth) acrylamide, N,
N-diethylaminopropyl (meth) acrylamide and the like; their inorganic or organic acids such as hydrochloric acid, sulfuric acid, and acetic acid; or the tertiary amino group-containing monomer and methyl chloride, benzyl chloride, dimethyl sulfate,
Examples include vinyl monomers containing a quaternary ammonium salt obtained by reaction with a quaternizing agent such as epichlorohydrin. By using these cationic group-containing monomers, a higher paper strength effect can be imparted when used as a paper strength enhancer in the production of paper having a neutral or weakly acidic papermaking pH.

The method for producing the amphoteric poly (meth) acrylamide derivative is carried out by appropriately combining the method for producing the anionic poly (meth) acrylamide derivative and the method for producing the cationic poly (meth) acrylamide derivative.

The (B) ionic poly (meth) acrylamide derivative of the present invention includes, in addition to the above (meth) acrylamide, anionic group-containing monomer and cationic group-containing monomer component, a crosslinkable monomer. A monomer obtained by copolymerizing a monomer having a chain transfer substituent or another copolymerizable monomer can be appropriately used.

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

Other copolymerizable monomers include, for example, N-substituted (meta) such as t-octylacrylamide.
Esters of anionic monomers such as acrylamides, (meth) acrylic acid and maleic acid with alcohols, styrene, α-methylstyrene, vinyltoluene, acrylonitrile, methylvinylether, isopropylacrylamide, vinyl acetate, α-olefin and the like. Can be The use amount of these other copolymerizable monomers is preferably about 30 mol% or less based on the total molar sum of the monomers. 3
If it exceeds 0 mol%, it is difficult to obtain a paper having a sufficient paper strength effect.

When (B) an ionic poly (meth) acrylamide derivative is produced by copolymerizing a crosslinkable monomer, a monomer having a chain transfer substituent, and other copolymerizable monomers. The content of the anionic group-containing monomer constituent unit and / or the cationic-containing monomer constituent unit is
1 to 3 with respect to the total molar sum of the monomer components constituting the polymer
It is about 0 mol%. Further, in order to obtain a desired effect of improving paper strength, the amount of (meth) acrylamide used is preferably 50 mol% or more based on the total molar sum of the monomer components constituting the polymer.

As the method for copolymerizing the above-mentioned monomer to obtain the (B) ionic poly (meth) acrylamide derivative of the present invention, various conventionally known methods can be adopted. For example,
A predetermined reaction vessel is charged with the predetermined amount of the monomer and water, and a redox polymerization initiator in the form of a persulfate such as potassium persulfate or ammonium persulfate, or a combination thereof with a reducing agent such as sodium hydrogen sulfite. Alternatively, a normal radical polymerization initiator such as an azo initiator is added,
The aqueous solution of the (B) ionic poly (meth) acrylamide derivative of the present invention can be obtained by heating under stirring. In the case where an anionic group and / or a cationic group is introduced into a poly (meth) acrylamide derivative by a modification method, modification is performed according to a conventional method after polymerization.

The weight average molecular weight of the ionic poly (meth) acrylamide derivative (B) of the present invention is preferably 100,000 or more in order to obtain a desired paper strength effect. The weight average molecular weight is preferably 5,000,000 or less from the viewpoint of productivity when the aqueous solution does not become highly viscous and is mixed with (A) a starch containing a phosphate group.

The inorganic salt (C) used in the present invention includes alkali metal salts such as sodium chloride, sodium sulfate, sodium carbonate, potassium chloride and potassium sulfate; alkaline earth metal salts such as calcium chloride and barium sulfate; ammonium sulfate and the like. Ammonium salts and the like. These (C) inorganic salts are used alone or as a mixture of two or more. Among these (C) inorganic salts, alkali metal salts and ammonium salts are preferred.

In the present invention, a papermaking additive comprising a mixed solution containing (A) a starch containing a phosphate group, (B) an ionic poly (meth) acrylamide derivative and (C) an inorganic salt is used. . The mixing ratio of (A) the starch containing a phosphate group and (B) the ionic poly (meth) acrylamide derivative is such that the storage stability of the mixed solution, the paper strength effect are improved, and the paper is recycled. The determination is made with sufficient consideration so as to maintain the characteristics of starches such as good re-dissociation and low cost. Usually, in solid content ratio, (A)
About 50 to 98% by weight of starch containing phosphate group and (B) ionic poly (meth) acrylamide derivative 2
It is preferable to mix at a ratio of about 50% by weight. In particular, from the viewpoint of storage stability of the obtained mixed solution, the content of the (B) ionic poly (meth) acrylamide derivative is preferably 5% by weight or more.

The amount of the inorganic salt (C) to be used is 1 to 20 with respect to the weight sum (solid content) of (A) the starch containing a phosphate group and (B) the ionic poly (meth) acrylamide derivative.
% By weight. If the amount is less than 1% by weight, it is difficult to maintain the storage stability of the resulting mixed solution for a long time, and if it exceeds 20% by weight, a water separation phenomenon which is considered to be a salting out phenomenon occurs.

(A) starch containing a phosphate group, (B)
As a method of mixing the ionic poly (meth) acrylamide derivative and the inorganic salt (C), any method can be adopted as long as a uniform mixed state is achieved. For example,
There is a method in which gelatinized (A) starch containing a phosphate group, (B) an aqueous solution of an ionic poly (meth) acrylamide derivative, and (C) an inorganic salt are mixed in a container having a stirrer. Alternatively, mixing may be performed using a line mixer or the like instead of such a container. Further, after preliminarily mixing powdery (A) starch containing a phosphate group, (B) an aqueous solution of an ionic poly (meth) acrylamide derivative, and (C) an inorganic salt before gelatinization, the mixed solution is mixed. The mixture of the present invention can also be obtained by gelatinization.

The viscosity of the mixed solution is not particularly limited, but the viscosity of an aqueous solution or aqueous dispersion at which the concentration of the mixed solution becomes 10% by weight, measured at 25 ° C., is about 100 cps or more. It is preferable in terms of effect. Also, 200
What shows about 00 cps or less is preferable in that the storage stability of the mixture is excellent. The viscosity of the mixture is
The viscosity of the mixture is determined by a combination of (A) the viscosity of the starch paste liquid containing a phosphate group, (B) the viscosity of the aqueous solution of the ionic poly (meth) acrylamide derivative, and (C) the amount of the inorganic salt added. Is appropriately adjusted at the time of preparing the mixed solution so that the value falls within the above range.

In the method for producing paper or paperboard of the present invention, the pulp slurry contains (A) a starch containing a phosphate group, (B) an ionic poly (meth) acrylamide derivative, and (C) an inorganic salt. It is characterized in that papermaking is performed after adding a papermaking additive composed of a mixed liquid as a paper strength enhancer, except that the specific papermaking additive of the present invention is used as the paper strength enhancer. Note that the same conditions as in the method for producing paper or paperboard can be employed.

That is, the paper strength enhancer is usually added at a usage ratio of about 0.1 to 3% 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.

[0026]

The papermaking additive of the present invention has a high paper strength enhancing effect inherent to starch and also has a long-term storage stability.

[0027]

The present invention will now be described more specifically with reference to examples and comparative examples. Unless otherwise specified, parts and% are based on weight.

Production Example 1 91.9 parts of acrylamide, 899 parts of ion-exchanged water, 8.1 parts of acrylic acid, and 1 part of isopropyl alcohol were charged into a flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube. The air in the reaction system was replaced with nitrogen gas. Under stirring, the mixture was heated to 60 ° C., and 0.2 parts of ammonium persulfate and 0.1 part of sodium hydrogen sulfite were added as polymerization initiators, and polymerization was carried out at 85 to 90 ° C. for 120 minutes. An aqueous solution of 10.2% anionic polyacrylamide derivative having a viscosity of 2300 cps was obtained.

Production Examples 2 and 3 In Production Example 1, at least one of the kind of the monomer component and the amount used was changed as shown in Table 1, and the amount of the initiator was changed so as to obtain a desired viscosity. Otherwise in the same manner as in Production Example 1, an anionic polyacrylamide derivative aqueous solution was obtained. Table 1 shows the property values of the obtained aqueous solutions.
Shown in

[0030]

[Table 1]

The abbreviations in Table 1 are AM: acrylamide, AA: acrylic acid, IA: itaconic acid, AN:
Shows acrylonitrile.

Production Example 4 A flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube was charged with 77.8 parts of acrylamide, 900 parts of ion-exchanged water, and dimethylaminoethyl methacrylate.
After 7 parts and 6.5 parts of itaconic acid were charged and the pH was adjusted to 4 to 3 with sulfuric acid, all oxygen in the reaction system was removed through nitrogen gas. Heat to 60 ° C under stirring,
0.25 parts of ammonium persulfate and 0.1 part of sodium hydrogen sulfite were added as a polymerization initiator, and polymerization was carried out at 85 to 90 ° C. for 120 minutes.
% And an aqueous solution of an amphoteric polyacrylamide derivative having a viscosity of 4500 cps.

Production Examples 5 and 6 In Production Example 4, at least one of the kind of the monomer component and the amount used was changed as shown in Table 2, and the amount of the initiator was changed so as to obtain a desired viscosity. Otherwise in the same manner as in Production Example 1, an amphoteric polyacrylamide derivative aqueous solution was obtained. Table 2 also shows the property values of the obtained aqueous solutions.

[0034]

[Table 2]

In Table 2, DM: dimethylaminoethyl methacrylate, AP: dimethylaminopropylacrylamide. Others are the same as Table 1.

Production Example 7 860 parts of ion-exchanged water and 140 parts of urea phosphate starch (Oji Ace P340, manufactured by Oji Cornstarch Co., Ltd.) were placed in a flask equipped with a stirrer, thermometer, and reflux condenser, and stirred. The mixture was heated below and maintained at 85 to 90 ° C. for 1 hour to perform gelatinization. After cooling, pH 4 ~ with 10% sulfuric acid
It was adjusted to 5 and taken out. Solids concentration 13.1
% Urea phosphate starch paste having a viscosity of 2300 cps (25 ° C.) was obtained.

Production Examples 8 and 9 The same operations as in Production Example 7 were carried out except that the type of starch was changed as shown in Table 3 and the solid content concentration of the paste was adjusted as shown in Table 3. To obtain a starch paste solution. Table 3 shows the properties of the obtained starch paste solution.

[0038]

[Table 3]

Example 1 In a beaker equipped with a stirrer, the starch starch solution 12 of Production Example 7 was added.
3 parts, 40 parts of the aqueous solution of anionic polyacrylamide of Production Example 1, 2 parts of sodium chloride, and 35 parts of deionized water were weighed and stirred until the contents became uniform. A mixed solution having a solid content of 11.2% and a viscosity (25 ° C.) of 980 cps was obtained.

Examples 2 to 7 and Comparative Examples 1 to 6 In Example 1, the types of starch paste, aqueous solution of polyacrylamide and inorganic salts were changed as shown in Table 4,
The same as Example 1 except that the mixing ratio of the polyacrylamide derivative (solid content), the mixing ratio of inorganic salt / (starch and polyacrylamide derivative) (solid content), and the solid content concentration were adjusted as shown in Table 4. The operation was performed to obtain a mixed solution. Table 4 shows the properties of the obtained mixed solution.

[0041]

[Table 4]

(Evaluation 1: Storage stability of mixed solution) Production Example 7
Starch paste obtained in Examples 1 to 7, Examples 1 to 7 and Comparative Examples 1 to 6
Each of the mixed liquids obtained in the above was allowed to stand at 20 ° C. for 30 days, and changes in the state were visually observed. Table 5 shows the results.

[0043]

[Table 5]

(Manufacture of Paper 1) BKP was beaten with a Niagara beater, and pulps adjusted to 500 ml of Canadian Standard Freeness (CSF) were added to pulps.
After adding sodium carbonate as an H adjuster, a sulfuric acid band was further added to 1.0% with respect to pulp, and then a paper strength enhancer shown in Table 6 was added with 0.5% to pulp, followed by stirring and uniform mixing. . The obtained pulp slurry (pH 6.5) was diluted to 0.5%, and the basis weight was 1 using a tappi sheet machine.
The paper was made to be 00 g / cm 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. In the above (Evaluation 1: storage stability of the mixed solution), the same papermaking was carried out for the mixed solution stored for 15 days after mixing.

The T-peel strength (g / cm) of the paper obtained in Paper Production 1 was measured. Table 6 shows the results.

(T-shaped peel strength) Tappi No.
It measured according to 19-m.

[0047]

[Table 6]

(Manufacture of paper 2)
Papermaking was carried out in the same manner as in Example 1 except that sodium carbonate was not added as a modifier and calcium carbonate was added at 20% to pulp.

The breaking length (km) of the paper obtained in Paper Production 2 was measured. Table 7 shows the results.

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

[0051]

[Table 7]

(Manufacture of Paper 3) Used corrugated paper and used magazine paper were mixed at a weight ratio of 1: 1 and beaten with a Niagara beater to adjust to a Canadian Standard Freeness (CSF) of 360 ml. After adding 2% of the sulfuric acid band to the pulp, the paper strength enhancer shown in Table 8 was added to the pulp at 0.5%, and the mixture was stirred and uniformly mixed. The resulting pulp slurry (pH 5.6, calcium ion concentration 28
0 ppm) to 0.5%, and the paper is made with a tappy sheet machine to a basis weight of 160 g / cm ^2, and 5 kg
/ M ² for 2 minutes. Next, 1
Dry at 10 ° C. for 4 minutes, 20 ° C., 65% RH. H. For 24 hours.

The specific burst strength (kPa) of the paper obtained in Paper Production 3 was measured. Table 8 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.

[0055]

[Table 8]

Claims (5)

[Claims] 1. (A) starch containing a phosphate group,
(B) an ionic poly (meth) acrylamide derivative, and 1 to 2 with respect to the weight sum (solid content) of (A) and (B)
A papermaking additive comprising a mixture containing 0% by weight of (C) an inorganic salt. 2. The solid content ratio of (A) a starch group containing a phosphate group and (B) an ionic poly (meth) acrylamide derivative is (A) 50 to 98% by weight and (B) 50 to 98% by weight.
2. The papermaking additive according to claim 1, wherein the amount is from 2 to 2% by weight. 3. The viscosity (25 ° C.) at a concentration of 10% by weight of the mixture is 100 to 20,000 cps.
Or the papermaking additive according to 2. 4. An ionic poly (meth) acrylamide derivative (B) comprising an anionic group-containing monomer constituent unit and / or a cationic group-containing monomer constituent unit with respect to the total molar amount of monomers. The papermaking additive according to claim 1, 2 or 3, which contains 1 to 30 mol%. 5. A method for producing paper or paperboard, comprising adding the papermaking additive according to claim 1 to a pulp slurry and then making the paper.