JP2907498B2 - Papermaking additives - Google Patents

Description

The present invention relates to an improvement in a papermaking additive containing a Hoffman-degraded acrylamide polymer used in the papermaking industry.

More specifically, the strength in the paper layer (meaning the strength in the direction perpendicular to the plane of the paper; hereinafter referred to as Z-axis strength)
The present invention relates to a paper strength enhancer having a high effect of enhancing paper strength such as burst strength and compressive strength.

[Conventional technology]

BACKGROUND ART Conventionally, various papermaking additives have been used in a papermaking process in order to improve paper quality.

In particular, a paper-strengthening agent having a performance of improving paper strength is indispensable for papermaking as a particularly important chemical.

Examples of the paper strength enhancer include starches such as oxidized starch, pregelatinized starch, cationized starch, and dialdehyde starch; epichlorohydrin modified polyamide polyamine; Hereinafter, acrylamide-based paper-strengthening agents are used according to the purpose. Among them, acrylamide-based paper-strengthening agents are advantageous in their synthesis,
It is most widely and generally used because of its performance and ease of use.

So far known acrylamide-based paper strength agents include anionic polyacrylamide, or amphoteric polyacrylamide obtained by modification by Mannich reaction or Hoffman decomposition reaction, or copolymerization of cationic monomer. And amphoteric polyacrylamide obtained by the method described above.

These acrylamide-based paper strength enhancers, when added to a pulp slurry in a papermaking system, have not only a paper strength enhancement effect, but also a drainage improvement effect, a yield improvement effect of fillers, etc., used alone or in combination. Are simultaneously expressed.

However, due to the recent increase in the ratio of used paper in the papermaking process, the increase in the degree of white water closeness due to drainage regulations, and the deterioration of papermaking conditions such as the speeding up of papermaking machines. It is difficult for the various performances to be fully exhibited.

In particular, overcoming the reduction in paper strength is an important issue, and depending on the use of paper, various problems due to the reduction in Z-axis strength often hinder the use of the paper.

Specifically, in the paperboard field, for example, poor post-processing suitability due to low Z-axis strength generated by coated white balls and the like, and in the paper field, during off-wheel printing due to low Z-axis strength of coated paper. Blisters and lower surface strength.

As a paper strength enhancer for improving the Z-axis strength, for example,
As described in JP-A-55-108405, JP-A-58-152004, and Tokikai-62-59602, an acrylamide-based paper strength enhancer (hereinafter referred to as a Hoffman-degraded acrylamide-based paper Is abbreviated as "enhancing agent".

However, the base acrylamide-based polymer that undergoes the Hoffman decomposition reaction is basically a linear polymer, and the Hoffman decomposition product of the acrylamide-based polymer in which the linear polymer is bonded to a three-dimensional structure is:
The performance as a paper strength agent has not been considered at all, and its effect has not been known at all.

[Problems to be solved by the invention]

SUMMARY OF THE INVENTION The present invention provides an acrylamide-based paper strength enhancer by a Hoffman decomposition reaction having a high effect of enhancing paper strength such as Z-axis strength, burst strength, and compressive strength, especially under the deterioration of papermaking conditions.

If further improvements can be achieved by further devising the Hoffman-decomposed acrylamide-based paper strength enhancer, the amount of papermaking additives used can be reduced overall and papermaking costs can be reduced. In addition, many advantages are expected, such as a reduction in the amount of unfixed resin that can cause contamination in the papermaking system.

[Means for solving the problem]

The present inventors, in view of the above circumstances, as a result of intensive studies on the improvement of Hoffman degradation acrylamide-based paper strength agent,
Using an acrylamide-based polymer having a three-dimensional crosslinked structure in the main chain, the Huffman-degraded acrylamide-based paper strength enhancer obtained by subjecting this to Hoffman degradation is compared with a conventionally known Huffman-degraded acrylamide-based paper strength enhancer, Not only Z-axis strength, but also paper strength improvement such as burst strength and compression strength,
Furthermore, they have found that a remarkable effect is seen in the performance of improving the freeness and the like, and have completed the present invention.

That is, the present invention relates to a papermaking additive containing a Hoffman-decomposed acrylamide-based polymer obtained by reacting an acrylamide-based polymer with a hypohalite in a temperature range of 50 to 110 ° C in the presence of an alkali, Acrylamide-based polymer having the three-dimensional cross-linked structure in the main chain obtained by adding 0.01 to 1 mol% of a crosslinkable monomer and / or 0.01 to 5 mol% of a crosslinker in the polymer constituting monomers. A polymer or B) an acrylamide-based polymer is further graft-polymerized to provide a papermaking additive characterized by being an acrylamide-based polymer having a side chain structure in a main chain.

In the above-mentioned papermaking additives, it is presumed that all of the acrylamide-based polymers subjected to the Huffman reaction have a structure in which the polymer main chains are partially crosslinked.

By having a crosslinked structure between polymer main chains, the aqueous solution has a non-Newtonian viscosity.

Here, the fact that the polymer aqueous solution has a non-Newtonian viscosity is synonymous with the fact that the viscosity index n is less than 1 in the following equation.

S = kD ⁿ (S: shear stress, D: shear rate, k: constant, n: viscosity index) As a method of measuring the viscosity index n, various methods such as a rotational viscometer and a rheometer can be considered. As a method, the viscosity is measured while changing the rotation speed with a rotation viscometer, and the viscosity index n can be calculated from the correlation between the indicated value at that time and the rotation speed.

Generally, an aqueous solution of an acrylamide-based polymer has a Newtonian viscosity in a molecular weight range usually used as a paper strength enhancer, but a polymer produced by an ordinary method exhibits Newtonian viscosity. It shows Newtonian viscosity. However, it is possible to estimate the degree of crosslinking of the polymer from the value of the viscosity index n.

The acrylamide-based polymer in the present invention refers to a water-soluble polymer containing acrylamide and / or methacrylamide in an amount of 30 mol% or more based on the total moles of the monomers constituting the polymer.

Components other than acrylamide and / or methacrylamide in the acrylamide polymer include:
The following monomers can be exemplified, and they can be used as long as the water solubility of the polymer is not impaired.

Examples of nonionic monomers include styrene, acrylonitrile, vinyl acetate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate,
Suitable are various (meth) acrylate derivatives such as various methoxypolyethylene glycols.

Examples of anionic monomers acrylic acid, monocarboxylic acids such as methacrylic acid, itaconic acid, maleic acid,
Examples include dicarboxylic acids such as fumaric acid and sulfonic acids such as acrylamidomethylpropanesulfonic acid.

Examples of the cationic monomer include dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminoethyl (meth) acrylate, diethylaminopropyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide,
3 such as diethylaminopropyl (meth) acrylamide
Vinyl monomers having a tertiary amino group, or salts of inorganic acids or organic acids thereof such as hydrochloric acid, sulfuric acid or acetic acid, or vinyl monomers having a tertiary amino group and alkyl halides such as methyl chloride and methyl bromide, and benzyl chloride A vinyl monomer containing a quaternary ammonium salt obtained by reaction with an arylalkyl halide such as benzyl bromide, dimethyl sulfate, or a quaternizing agent such as epichlorohydrin;
There are cationic monomers having an allyl group such as dimethyldiallylammonium chloride.

The viscosity (25 ° C.) of the above-mentioned acrylamide-based polymer in an aqueous solution state is preferably 100 to 100,000 cps at a Brookfield viscosity of 7 to 20%, more preferably 500 to 50,000 cps in the concentration range.

Examples of the crosslinking monomer used in the present invention include bis (meth) acrylamides such as methylenebis (meth) acrylamide and hexamethylenebis (meth) acrylamide, ethylene glycol di (meth) acrylate, and polyethylene glycol di (meth) acrylate. Di (meth) acrylates, divinyl esters such as divinyl adipate and divinyl sebacate, and monomers having two double bonds represented by divinylbenzene, etc., trimethylolpropane triacrylate, N, N
-Reaction of a monomer having three double bonds represented by diallyl acrylamide or the like, or a reaction of methylol (meth) acrylamide, glycidyl (meth) acrylate, N-methoxymethyl (meth) acrylamide, N-methoxybutyl (meth) acrylamide, etc. For example, a vinyl monomer having a functional group can be used. Two or more of these monomers may be used in combination.

The quantitative ratio of the above-mentioned crosslinkable monomer is from 0.01 to 1 mol%, preferably from 0.02 to 0.5 mol%, based on the total mol of the polymer constituting monomers.

The cross-linking agent used in the present invention means one having a property capable of cross-linking between the polymer main chains of the acrylamide-based polymer of the present invention by a covalent bond.

Specifically, formalin, glyoxal, glutaraldehyde, epichlorohydrin and the like can be exemplified.

The quantitative ratio of the above-mentioned crosslinking agent is 0.01 to 5 mol%, preferably 0.02 to 5 mol%, based on the total mol of the polymer constituting monomers.
3 mol%.

The graft-polymerized acrylamide polymer used in the present invention can be obtained by performing polymerization in two or more stages.

As a specific method, there are a method in which polymerization is performed by adding a polymerization initiator in two or more stages, and a method in which polymerization is performed by adding a monomer in two or more stages.

In the two-stage addition method of the polymerization initiator, the second stage is preferably added after the time when the polymerization starts and heat is generated, the temperature rises, and the rising speed starts to decrease.

The amount of initiator added at that time depends on the initial polymerization (synthesis of the main chain).
It is appropriate that the amount is equal to or less than the amount of the monomer added, preferably 10 to 50%.

At this time, the polymerization temperature may be raised by heating, or a different initiator may be added.

Also in the two-stage monomer addition method, the timing of the second-stage monomer addition is preferably after the time when the rate of increase in the polymerization temperature of the first-stage monomer starts to decrease.

The ratio of the monomer addition amount (Y) in the second stage to the monomer addition amount (X) in the first stage is X: Y = 10: 90 by weight.
90:10, preferably X: Y = 30: 70-70: 30.

At this time, a polymerization initiator may be added together, or the temperature may be increased by heating.

As a polymerization solvent for the acrylamide-based polymer used in the present invention, a polar solvent such as water, alcohol, or dimethylformamide can be used, but water-soluble polymerization is desirable from the viewpoint of economy and the like.

The polymerization initiator of the acrylamide polymer used in the present invention is not particularly limited as long as it is soluble in a polymerization solvent.

Specific examples include ammonium persulfate, potassium persulfate, hydrogen peroxide, tert-butyl peroxide and the like.
In this case, although it can be used alone, it is combined with a reducing agent such as a sulfite, a bisulfite, or an organic amine such as N, N, N ', N'-tetramethylethylenediamine, and further, a reducing sugar such as aldose or ketose. Thus, it is preferable to use it as a redox polymerization initiator.

Also, azo compounds can be used, specifically, azobisisobutyronitrile, 2,2′-azobis-2-amidinopropane hydrochloride, 2,2′-azobis-2,4-dimethylvaleronitrile, 4,4'-azobis-4-cyanovaleic acid and salts thereof can be exemplified.

When the acrylamide-based polymer obtained by the graft polymerization is obtained, a transition metal ion such as a cerium ion or a ferric ion can be used as the polymerization initiator in addition to the polymerization initiator described above. Yes, it may be used in combination with the above-mentioned polymerization initiator.

Two or more of these initiators can be used in combination. In addition to the initiator, a chain transfer agent such as isopropyl alcohol and allyl alcohol can be used as needed.

Next, a Hoffman decomposition reaction of the acrylamide-based polymer produced by the above method is performed.

At that time, when the acrylamide-based polymer as a raw material is produced in an aqueous solution, the acrylamide-based polymer can be used for the reaction as it is or after dilution as necessary.

The Hoffman decomposition reaction is carried out in the alkaline region, that is, by the action of hypohalous acid on the amide group of the acrylamide polymer in the coexistence of an alkaline substance, and hypochlorous acid is hypochlorous acid or hypobromite. acid,
Hypoiodic acid.

Examples of the hypochlorite include alkali metal or alkaline earth metal salts of such hypochlorous acid. Specifically, sodium hypochlorite, potassium hypochlorite, lithium hypochlorite, Examples include calcium chlorite, magnesium hypochlorite, and barium hypochlorite. Similarly, hypobromous acid and hypoiodic acid include hypobromous acid and alkali metal or alkaline earth metal salts of hypoiodous acid. It is also possible to generate a hypohalite by blowing a halogen gas into an alkaline solution.

On the other hand, examples of the alkaline substance include alkali metal hydroxides, alkaline earth metal hydroxides, and alkali metal carbonates. Among them, alkali metal hydroxides are preferable, and sodium hydroxide, potassium hydroxide, and water. Lithium oxide and the like.

The amount of the above-mentioned substance added to the acrylamide-based polymer is 5 to 5 with respect to the amide group in hypohalite.
It is 200 mol%, preferably 10 to 150 mol%, and in an alkaline substance, it is 5 to 400 mol%, preferably 10 to 300 mol%, based on the amide group.

The range of the alkaline region, that is, the pH range is generally about 11 to 14.
In the range.

The reaction temperature of the Hoffman decomposition reaction can be selected from the range of 0 to 110 ° C., but a higher temperature range of 50 to 110 ° C. than the lower temperature side is preferable because the effect as a paper strength enhancer is higher. The temperature is more preferably in the range of 60 to 100 ° C.

The concentration of the acrylamide-based polymer at the time of performing the Hoffman decomposition reaction is generally about 0.1 to 25% by weight, but since the gelation is likely to occur when the reaction concentration is high, the concentration is usually in the range of 0.1 to 15% by weight. Is preferred.

When the Hoffman decomposition reaction is performed at a high temperature for a short period of time, if the reaction temperature is less than 1%, there is a problem that the reaction rate becomes slow. Therefore, it is more preferably 1 to 10% by weight.

The Hoffman decomposition reaction time can vary depending on the reaction temperature and the polymer concentration in the reaction solution, but a low temperature requires a long time, whereas a high temperature of 50 ° C. or higher can perform the reaction in a short time. .

For example, when the polymer concentration is about 1 to 10% by weight, 50
Within 10 minutes at 65 ° C, within several minutes at 65 ° C and within several tens of seconds at 80 ° C are sufficient. The higher the polymer concentration, the shorter the reaction time.

Next, after carrying out the reaction under the above conditions, in the present invention, it is desirable to stop the reaction in order to suppress the progress of the side reaction. However, when used immediately after the reaction, the reaction need not necessarily be stopped.

The reaction can be stopped by (1) adding a reducing agent such as sodium sulfite, sodium thiosulfate, ethyl malonate, thioglycerol, or triethylamine; (2) cooling to a low temperature; and (3) adjusting the pH of the solution to an acid. The method of lowering by addition may be used alone or in combination.

The papermaking additive of the present invention is used in the papermaking process of paper or paperboard, and its addition brings great efficacy.

At this time, the amount of the papermaking additive added is 0.005 to 5% by weight, preferably 0.005 to 5% by weight, based on the weight of the dry solid content of the raw pulp.
It is in the range of 0.01 to 2%.

The papermaking additive of the present invention can be used alone, but if necessary, it is preferable to perform papermaking in combination with an anionic resin such as a sulfate band or an anionic acrylamide polymer.

These chemicals can be added in any order or simultaneously.

The addition ratio of the cationic acrylamide polymer to the anionic resin can be arbitrarily selected, and is in the range of 100: 0 to 10:90 in terms of the weight of the solid content.

The place for adding the papermaking additive of the present invention may be any place before the wet sheet is formed, and it is usually better to add the additive to a place near the papermaking wire portion.

The acrylamide-based paper-strengthening agent by the Hoffman decomposition reaction of the present invention has a high effect of enhancing paper-strength such as Z-axis strength, bursting strength, and compressive strength, especially under the deterioration of papermaking conditions.

Therefore, a further improvement in performance can be achieved, the amount of papermaking additives used can be reduced as a whole, and not only the cost of papermaking can be reduced, but also unfixed resin which can cause contamination in the papermaking system. Many benefits are expected, including a reduction in volume.

〔Example〕

Next, the present invention will be described specifically with reference to Examples and Application Examples, but the present invention is not necessarily limited to the following Examples and Application Examples. In addition,% and pp
Unless otherwise specified, “m” means “% by weight” and “ppm by weight”.

Comparative Example 7 A four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube was charged with 70.93 g of acrylamide and 0.154 g of methylenebisacrylamide, and water was added to bring the total amount to 444.
3 g. Thereafter, the internal temperature was raised to 45 ° C. while blowing nitrogen gas. While stirring, 0.57 g of ammonium persulfate and 0.26 g of sodium bisulfite were added to initiate polymerization. Thereafter, the temperature was maintained at 85 ° C., and water was added two hours after the start of the polymerization to complete the polymerization. As a result, the polymer component was 15% and the Brookfield viscosity at 25 ° C. was No. 4
Rotor, 3700cps at 60rpm, No3 rotor, 4500c at 6rpm
ps, that is, an aqueous solution of an acrylamide polymer having a viscosity index of 0.82 was obtained.

Thereafter, 237.0 g of this aqueous solution was cooled to 5 ° C., and 40% NaOH 20.0 g available chlorine 12.0% was added to the aqueous solution while stirring was continued.
Of NaOCl and 118.5 g of water were mixed and dropped, and reacted at 24 ° C. for 24 hours. After the reaction is completed, pH is adjusted with 20% HCl.
Was adjusted to 4.5, water at 5 ° C was added, and the Hoffman-decomposed acrylamide paper strength was 6.0% in terms of acrylamide-based polymer, the cation equivalent by colloid titration was 2.39meq / g, and the anion equivalent was 0.28meq / g. An enhancer A-1 was obtained.

Example 1 The aqueous solution of an acrylamide polymer obtained in Comparative Example 7 was diluted with distilled water to obtain a 2% aqueous solution. Then this aqueous solution
355.4 g was heated to 80 ° C., and a mixed solution of 4.0 g of 40% NaOH and 11.64 g of NaOCl containing 12.2% of available chlorine was added to the aqueous solution at a time while stirring was continued. After the addition, the mixture was allowed to react for 5 seconds, which was 1.92% in terms of the acrylamide-based polymer, and had a cation equivalent of 2.42 meq / g and an anion equivalent of 0.30 meq / g by colloid titration. I got

Comparative Examples 8 and 9 Examples 2 and 3 Comparative Example 7 or Example 1 except that the amount of methylenebisacrylamide and the amount of the polymerization initiator associated therewith were changed.
In the same manner as described above, Hoffman-decomposed acrylamide-based paper strength agents A-3 to A-6 were obtained.

 Table 1 shows the synthesis conditions and physical properties of A-3 to A-6.

Comparative Example 1 A four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube was charged with 71.0 g of acrylamide, and water was added to make a total amount of 443.8 g. Thereafter, the internal temperature was raised to 45 ° C. while blowing nitrogen gas. With stirring, ammonium persulfate 0.22g, sodium bisulfite
The polymerization was started by adding 0.10 g. Thereafter, the temperature was maintained at 85 ° C., and after 2 hours from the start of the polymerization, water was added, and the polymerization was completed. When the polymerization was completed, the Brookfield viscosity at 25 ° C. was 15%, the Brookfield viscosity at 25 ° C. was 4510 cps at 60 rpm, the No. 3 rotor was 6 rpm. Thus, an aqueous acrylamide polymer solution having a viscosity index of 1.00 was obtained at 4500 cps.

Thereafter, 236.7 g of this aqueous solution was cooled to 5 ° C., and 20.0 g of 40% NaOH and 12.2 g of available chlorine were added to the aqueous solution while stirring.
58.2 g of NaOCl and 118.3 g of water were mixed and dropped, and reacted at 24 ° C. for 24 hours. After the reaction, p with 20% HCl
H was adjusted to 4.5, water at 5 ° C was added, and it was 6.0% in terms of the acrylamide-based polymer. The cation equivalent by colloid titration was 2.35 meq / g, and the anion equivalent was 0.28 meq / g. Paper strength enhancer B-1 was obtained.

Comparative Example 2 The aqueous acrylamide polymer solution obtained in Comparative Example 1 was diluted with distilled water to obtain a 2% aqueous solution. Then this aqueous solution
355.05 g was heated to 80 ° C., and a mixed solution of 4.0 g of 40% NaOH and 11.64 g of NaOCl containing 12.2% of available chlorine was found in the aqueous solution at a time while stirring was continued. After the addition, the mixture was allowed to react for 5 seconds, which was 1.92% in terms of acrylamide-based polymer and had a cation equivalent of 2.43 meq / g and an anion equivalent of 0.30 meq / g by colloid titration. I got

Comparative Example 10 63.9 g of acrylamide, 5.3 g of acrylonitrile, and 0.162 g of 37% formalin were charged into a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube, and water was added to make a total amount of 577.17 g. Thereafter, the internal temperature was raised to 45 ° C. while blowing nitrogen gas. While stirring, 0.40 g of ammonium persulfate and 0.18 g of sodium bisulfite were added to initiate polymerization. Thereafter, the temperature was maintained at 75 ° C., and after 3 hours from the start of the polymerization, water was added, and the polymerization was completed.When the polymerization was completed, the Brookfield viscosity at 25 ° C. was 4% at 4 ° C.
An acrylamide-based polymer aqueous solution having a viscosity index of 0.85 was obtained at 6 rpm at 5,650 cps. Then, 346.3 g of this aqueous solution
And 40% NaOH 3 in the aqueous solution with continued stirring.
0.0g, 87.3g of NaOCl with 12.2% available chlorine were added dropwise and mixed.
The reaction was carried out for 3 hours while maintaining the temperature. After completion of the reaction, 20% HC
The pH is adjusted to 4.5 with l, water at 15 ° C is added, and the acrylamide polymer is 6.0% in terms of acrylamide polymer. The cation equivalent by colloid titration is 3.51meq / g and the anion equivalent is 0.41meq / g.
Of Hoffman-decomposed acrylamide-based paper strength agent A-7 was obtained.

Example 4 The aqueous solution of an acrylamide polymer obtained in Comparative Example 10 was diluted with distilled water to obtain a 2% aqueous solution.

Next, 346.3 g of this aqueous solution was heated to 75 ° C., and while stirring, 6.0 g of 40% HaOH and 12.2% of available chlorine were added to the aqueous solution.
l 17.46 g of the mixed solution was added at once.

After the addition, the mixture was reacted for 10 seconds, and was 1.87% in terms of the acrylamide-based polymer. The cation equivalent by colloid titration was 3.53 meq / g and the anion equivalent was 0.40 meq / g. I got

Comparative Example 11, Example 5, Comparative Example 12, Example 6 Huffman degradation was performed in the same manner as in Comparative Example 10 or Example 4, except that the amount of 37% formalin and the amount of the polymerization initiator involved were changed. Acrylamide paper strength agent A-
9 to A-12 were obtained.

 Table 1 shows the synthesis conditions and physical properties of A-9 to A-12.

Comparative Example 3 63.9 g of acrylamide and 5.3 g of acrylonitrile were charged into a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube, and water was added to make a total amount of 576.7 g. Thereafter, the internal temperature was raised to 45 ° C. while blowing nitrogen gas.

While stirring, 0.18 g of ammonium persulfate and 0.08 g of sodium bisulfite were added to initiate polymerization. Thereafter, the temperature was maintained at 75 ° C., and after 3 hours from the start of the polymerization, water was added, and the polymerization was completed.
Brookfield viscosity at No.4 rotor, 60rpm
5530 cps, No. 3 rotor, and 6500 rpm at 5500 cps, that is, an aqueous solution of an acrylamide polymer having a viscosity index of 1.01 was obtained.

Thereafter, 346.0 g of this aqueous solution was cooled to 5 ° C., and 30.0 g of 40% NaOH and 12.2 g of available chlorine were added to the aqueous solution while stirring.
87.3 g of NaOCl% was added dropwise thereto, and the mixture was reacted for 3 hours while keeping the temperature at 15 ° C. After completion of the reaction, the pH was adjusted to 4.5 with 20% HCl, water was added at 15 ° C, and the acrylamide-based polymer was 6.0% in terms of cation equivalent by colloid titration.
A Hoffman-degraded acrylamide paper strength agent B-3 having 3.48 meq / g and an anion equivalent of 0.42 meq / g was obtained.

Comparative Example 4 The aqueous solution of an acrylamide polymer obtained in Comparative Example 3 was diluted with distilled water to obtain a 2% aqueous solution.

Next, 346.0 g of this aqueous solution was heated to 75 ° C., and 6.0 g of 40% NaOH and 12.2% of available chlorine were added to the aqueous solution while stirring was continued.
A mixed solution of 17.46 g of NaOCl was added all at once. After addition, 10
After reacting for 2 seconds, 1.
87%, cation equivalent by colloid titration is 3.51me
A Huffman-degraded acrylamide-based power enhancer B-4 having a q / g and anion equivalent of 0.39 meq / g was obtained.

Comparative Example 13 A four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube was charged with 31.95 g of acrylamide and 2.65 g of acrylonitrile, and water was added to make a total amount of 288.3 g.
Thereafter, the internal temperature was raised to 45 ° C. while blowing nitrogen gas.

While stirring, 0.132 g of ammonium persulfate and 0.06 g of sodium bisulfite were added to initiate polymerization. Forty-five minutes after the addition of the polymerization initiator, the temperature was raised to 76 ° C., and then kept at 75 ° C. for one hour to obtain an acrylamide-based polymer aqueous solution.
Thereafter, 35.5 g of acrylamide and water were charged into the acrylamide-based polymer aqueous solution, and the total amount was 584.17 g.
And the internal temperature was adjusted to 45 ° C.

While stirring, an aqueous solution of 3.2 g of 1N nitric acid aqueous solution of cerium ammonium nitrate was added, and the reaction was carried out at 60 ° C. for 1 hour. After that, water was added to complete the polymerization, and the polymer component was 10%. The Brookfield viscosity at 25 ° C was 5 cps at 4 rpm, 5000 cps at 60 rpm, and 5550 cps at 6 rpm.
s, that is, an acrylamide-based polymer aqueous solution having a viscosity index of 0.90 was obtained.

Thereafter, 350.5 g of this aqueous solution was cooled to 10 ° C., and 10.0 g of 40% NaOH and 12.2 g of available chlorine were added to the aqueous solution while stirring was continued.
29.1 g of NaOCl% was added dropwise thereto and reacted at 10 ° C. for 10 hours. After completion of the reaction, the pH was adjusted to 4.5 with 20% HCl, water was added at 10 ° C, and the acrylamide-based polymer was 6.0% in terms of cation equivalent by colloid titration.
A Huffman-degraded acrylamide paper strength agent A-13 having 1.28 meq / g and anion equivalent of 0.14 meq / g was obtained.

Example 7 The aqueous solution of an acrylamide polymer obtained in Comparative Example 13 was diluted with distilled water to obtain a 2% aqueous solution.

Next, 350.5 g of this aqueous solution was heated to 70 ° C., and 2.0 g of 40% NaOH and 12.2% of available chlorine were added to the aqueous solution while stirring.
A mixed solution of 5.82 g of NaOCl was added all at once. After addition, 15
After reacting for 2 seconds, 1.
96%, cation equivalent by colloid titration 1.29me
Comparative Example 5 A four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, and a nitrogen gas inlet tube was obtained. Then, 67.45 g of acrylamide and 2.65 g of acrylonitrile were charged into the mixture, and water was added to adjust the total amount to 584.17 g.
Thereafter, the internal temperature was raised to 45 ° C. while blowing nitrogen gas. With stirring, ammonium persulfate 0.18
g and sodium bisulfite 0.08 g were added to initiate polymerization. Thereafter, the temperature was maintained at 85 ° C., and after 3 hours from the start of the polymerization, water was added, and the polymerization was completed.
No.4 rotor with Brookfield viscosity at 25 ℃, 6
An acrylamide-based polymer aqueous solution having 5880 cps at 0 rpm and a No. 3 rotor and 5870 cps at 6 rpm, that is, a viscosity index of 1.00 was obtained.

Thereafter, 350.5 g of this aqueous solution was cooled to 10 ° C., and 10.0 g of 40% NaOH and 12.
29.1 g of 2% NaOCl was added dropwise thereto, and the mixture was reacted for 10 hours while maintaining the temperature at 10 ° C. After completion of the reaction, the pH was adjusted to 4.5 with 20% HCl, water was added at 10 ° C, and the acrylamide-based polymer was 6.0% in terms of cation equivalent by colloid titration.
A Hoffman-degraded acrylamide paper strength agent B-5 having 1.28 meq / g and an anion equivalent of 0.15 meq / g was obtained.

Comparative Example 6 The aqueous solution of an acrylamide polymer obtained in Comparative Example 9 was diluted with distilled water to obtain a 2% aqueous solution. Then this aqueous solution
350.5 g was heated to 70 ° C., and a mixed solution of 2.0 g of 40% NaOH and 5.82 g of NaOCl containing 12.2% of available chlorine was added to the aqueous solution at a time while stirring was continued. After the addition, the mixture was allowed to react for 15 seconds. The acrylamide-based polymer was 1.96%, the cation equivalent by colloid titration was 1.30 meq / g, and the anion equivalent was
A Hoffman-decomposed acrylamide paper strength agent B-6 of 0.13 meq / g was obtained.

Table 1 shows a list of the paper strength agents of Examples 1 to 7 and Comparative Examples 1 to 12.

Application Example 1% sulfuric acid band was added to 1% pulp slurry of 1% pulp slurry to 1% pulp slurry of corrugated waste paper beaten to 450 ml of CFS and stirred for 1 minute. The pH of the pulp slurry after stirring was 5.5.

To this 1% pulp slurry, a 1% aqueous solution of the paper strength agent produced in Comparative Example 7 was added to the pulp at a solid content of 0.5%.
And stirred for 1 minute. After completion of the stirring, Canadian Standard Freeness (CSF) was measured using a part of the pulp slurry according to JIS-P-8121.

In addition, a part is made into paper with a basis weight of 150 g / m ² by a tappy standard sheet machine, the burst strength is determined by JIS-P-8112, the compressive strength is determined by JIS-P-8126, and Kumagaya Riki Kogyo Co., Ltd. The Z-axis strength was measured with an internal bond tester.

Moreover, the same operation as the paper strength enhancer produced in Example 1 was performed also about the paper strength enhancer produced in Examples 1-7 and Comparative Examples 2-12.

The results are shown in Tables 2-1 to 2-3. The paper strength enhancers used here were all those immediately after production.

Blank indicates no added sulfuric acid band and paper strength agent.

[Effect of the Invention] The papermaking additive according to the present invention, that is, the paper strength enhancer is shown in Table 1.
As shown in the above, compared with a Hoffman-decomposed acrylamide-based paper strength enhancer obtained using a conventionally known acrylamide-based polymer, the effect of improving drainage, Z-axis strength, burst strength, compressive strength, etc. is high. . As for the Hoffman decomposition reaction conditions, the effect of the Hoffman decomposition acrylamide paper strength agent reacted at a high temperature in a short time is higher than that of a reaction performed at a low temperature for a long time.

As described above, it is clear that the papermaking additive according to the present invention has excellent performance.

Claims (2)

(57) [Claims] 1. A papermaking additive comprising a Hoffman-decomposed acrylamide-based polymer obtained by reacting an acrylamide-based polymer with a hypohalite in the presence of an alkali in a temperature range of 50 to 110 ° C. Acrylamide-based polymer having the three-dimensional crosslinked structure in the polymer main chain obtained by adding 0.01 to 1 mol% of a crosslinkable monomer and / or 0.01 to 5 mol% of a crosslinker in the polymer constituting monomer A) Polymer or B) An additive for papermaking which is characterized by being an acrylamide polymer having a side chain structure in the polymer main chain by further graft-polymerizing the acrylamide polymer main chain. 2. A) Acrylamide having a three-dimensional cross-linked structure in a polymer main chain obtained by adding 0.01 to 1 mol% of a cross-linkable monomer and / or 0.01 to 5 mol% of a cross-linking agent in a monomer constituting a polymer. Or B) Acrylamide-based polymer main chain is further graft-polymerized, and the acrylamide-based polymer having a side chain structure in the polymer main chain is reacted with hypohalite at 50 ° C or more in the presence of an alkali. A method for producing an acrylamide-based polymer for a papermaking additive, which comprises subjecting to Hoffman decomposition.