WO2015056557A1

WO2015056557A1 - Intermediate for papermaking additive, and method for manufacturing papermaking additive

Info

Publication number: WO2015056557A1
Application number: PCT/JP2014/075871
Authority: WO
Inventors: 嘉義陳
Original assignee: 栗田工業株式会社
Priority date: 2013-10-15
Filing date: 2014-09-29
Publication date: 2015-04-23
Also published as: CN105593435A; KR101626284B1; JP2015078453A; KR20160042171A; CN105593435B; JP5817802B2

Abstract

　Provided are an intermediate that yields a papermaking additive having excellent balance between a yield improvement effect and a freeness improvement effect, and a method for manufacturing the papermaking additive. An acrylamide polymer included in the intermediate for the papermaking additive has an intrinsic viscosity of 12.5-28 dL/g and an anionization degree of 0.005 meq/g or less. No crosslinking agent is added in a polymerization reaction step for generating the acrylamide polymer included in the intermediate. The method for manufacturing the papermaking additive has a step for subjecting the intermediate for the papermaking additive to a Hoffman degradation reaction.

Description

Intermediate for papermaking additive and method for producing papermaking additive

The present invention relates to a papermaking additive intermediate comprising a polyacrylamide polymer and a method for producing a papermaking additive characterized by subjecting the intermediate to a Hofmann decomposition reaction.

In recent years, various paper additives for improving yield and drainage have been used in the paper manufacturing process. For example, as a yield improver, a cationic copolymer (C-PAM) of dimethylaminoethyl (meth) acrylate (DAA) and acrylamide (AAM) is mainly used. In addition, polyethyleneimine and polyvinylamine are mainly used as the drainage improver.

The DAA-PAM yield improver has a large molecular weight, but the DAA cationic group is separated from the main chain. Therefore, although the effect of improving the yield rate is remarkable, there is a problem that the floc of papermaking is large, the formation often collapses, and poor dehydration is caused.

Polyethyleneimine and polyvinylamine have a high drainage improvement effect, but they have a problem that they have a low molecular weight and need to be used in a large amount and lack a yield improvement effect. In particular, since polyethyleneimine is too cationic, it cannot be effective unless it is added in a large amount. Polyvinylamine has a problem that it is expensive and difficult to use.

Although an additive for papermaking utilizing the Hoffman reaction has been developed, it was a paper strength agent mainly for the purpose of enhancing paper strength. In addition, the Hoffman reactant has a problem in that it cannot obtain a sufficient spread of molecular structure and a floc is weak, so that a sufficient yield improvement effect or drainage improvement effect cannot be obtained (see Patent Document 1).

Japanese Patent No. 2907498

Although these paper additives have high effects in some properties in terms of yield improvement effect, drainage improvement effect, etc., they do not have sufficient effects in all these properties, The additive was unbalanced.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an intermediate for providing a paper additive with an excellent balance of yield improvement effect and drainage improvement effect and a method for producing the paper additive. And

The present inventor has a well-balanced effect of improving the yield and the drainage of the paper additive obtained by subjecting the intermediate of the paper additive containing a predetermined acrylamide polymer to the Hofmann decomposition reaction. As a result, the present invention has been completed. Specifically, the present invention provides the following.

(1) An intermediate of a paper additive containing an acrylamide polymer having an intrinsic viscosity of 12.5 to 28 dl / g and an anionization degree of 0.05 meq / g or less.

(2) The intermediate of the papermaking additive according to (1), wherein no crosslinking agent is added in the polymerization reaction step for producing the acrylamide polymer.

(3) A method for producing a papermaking additive comprising a step of subjecting the intermediate of the papermaking additive described in (1) or (2) to a Hofmann decomposition reaction.

(4) The method for producing a paper additive according to (3), wherein in the Hofmann decomposition reaction, the acrylamide polymer is subjected to the reaction as a solution of 2% by mass or less.

According to the present invention, it is possible to provide a new papermaking additive having a good balance between yield improvement and drainage improvement.

Hereinafter, embodiments of the present invention will be described, but the present invention is not particularly limited thereto.

<Intermediate of paper additive>
The intermediate of the papermaking additive in the present invention is an acrylamide having an intrinsic viscosity (measured value at 30 ° C. in 1N—NaNO ₃ aqueous solution) of 12.5 to 28 dl / g and anionization degree of 0.05 meq / g or less. It is characterized by containing a system polymer. When the inherent clay and the anionization degree are within the above ranges, the papermaking additive can have a sufficient effect in a balanced manner in terms of yield improvement and drainage improvement.

Intrinsic viscosity and molecular weight of acrylamide polymers are generally correlated. That is, when the intrinsic viscosity decreases, the molecular weight decreases, and the freeness and yield decrease. Therefore, in order to improve drainage and yield, the intrinsic viscosity of the acrylamide polymer needs to be 12.5 dl / g or more. The intrinsic viscosity of the acrylamide polymer is more preferably 13.0 dl / g or more, further preferably 14.0 dl / g or more, and most preferably 14.5 dl / g or more. On the other hand, if the intrinsic viscosity of the acrylamide polymer is too high, the molecular weight becomes too large, and when added in the papermaking process, it acts as a flocculant and the papermaking texture is destroyed. Therefore, in order to prevent aggregation, the intrinsic viscosity of the acrylamide polymer needs to be 28 dl / g or less. The intrinsic viscosity of the acrylamide polymer is more preferably 24 dl / g or less, further preferably 20 dl / g or less, and most preferably 16 dl / g or less. The intrinsic viscosity is calculated by measuring the flow time using a Canon Fenceke viscometer and using the Huggins equation and the Mead-Fuoss equation from the measured value.

If the degree of anionization of the acrylamide polymer is too high, an ionic reaction between a cation group and an anion group occurs in the acrylamide polymer molecule, resulting in a decrease in yield. Therefore, the anionization degree of the acrylamide polymer for improving the yield is preferably 0.05 meq / g or less, more preferably 0.04 meq / g or less, and further preferably 0.03 meq / g or less. And most preferably 0.01 meq / g or less.

The degree of anionization is represented by a colloid equivalent value, and the colloid equivalent value is measured by the following method as described in paragraph 0029 of JP-A-2009-228162.

[Method of measuring colloidal equivalent value]
An anionic polymer compound diluted in a 50 ppm aqueous solution (diluted with pure water) is collected in a 100 ml graduated cylinder and transferred to a 200 ml beaker. After adding 0.5 ml of 2N sodium hydroxide solution (manufactured by Wako Pure Chemical Industries, Ltd.) with a whole pipette while stirring the rotor, N / 200 methyl glycol chitosan solution (manufactured by Wako Pure Chemical Industries, Ltd.) ) Add 5 ml with a whole pipette. Put 2 to 3 drops of toluidine blue indicator (Wako Pure Chemical Industries, Ltd.) and titrate with N / 400 polyvinyl alcohol potassium sulfate solution (Wako Pure Chemical Industries, Ltd.). The end point is the point where the blue color changes to magenta and does not disappear after a few seconds. Similarly, a blank test is performed with pure water (blank).
Colloid equivalent value (meq / g) = [Measured value of anionic polymer compound (ml) −Titrate of blank test (ml)] / 2

The high drainage is particularly effective in papermaking systems that do not use sulfuric acid bands. Not only that, it means that water drainage in the paper machine is good, and the formation of a tight floc has the effect that press dehydration is good, leading to a reduction in steam consumption in the drying section. That is, the present invention also has a feature of high press dewaterability.

High press dewaterability means that wet paper web moisture at the press inlet is reduced, and crushing is suppressed. Moreover, since the steam consumption of a drying part is the bottleneck of the paper making speed of a normal paper machine, steam reduction leads to the speeding up of the machine.

In the present invention, the yield rate is remarkably improved as compared with polyethyleneimine, and the paper strength is superior as compared with polyethyleneimine and polyvinylamine.

Paper additive refers to what is used as an additive in the paper making process, and is mainly used for the purpose of improving yield, improving drainage or improving paper strength. However, it is not necessarily limited to these purposes, and may be appropriately selected according to the purpose.

The intermediate of the paper additive is an acrylamide polymer that is a precursor of the paper additive. More specifically, it refers to an acrylamide polymer intended to be subjected to a Hofmann decomposition reaction.

Acrylamide polymer refers to a polymer obtained by polymerization reaction of acrylamide, and may contain other cationic monomers. The anionic monomer may or may not be contained, but the acrylamide polymer obtained by the polymerization reaction has an intrinsic viscosity of 12.5 to 28 dl / g and an anionization degree of 0.05 meq / g or less. Need to be. However, in order to improve the yield by lowering the degree of anionization and suppressing hydrolysis decomposition of the acrylamide polymer during polymerization, it is preferable not to contain an anionic monomer.

The acrylamide polymer preferably has a linear structure (linear polymer) in order to further improve the drainage and yield of the paper additive. That is, as a monomer other than acrylamide used for the polymerization reaction of the acrylamide polymer, it is preferable that the crosslinkable monomer is not polymerized.

Examples of the crosslinkable monomer include methylene bisacrylamide, hexamethylene bisacrylamide, N, N-diallylacrylamide trimethylolpropane triacrylate, methylolacrylamide, and N-methoxymethylacrylamide.

As the solvent used for the polymerization reaction of the acrylamide polymer, for example, water, alcohol, dimethylformamide and the like can be used. In view of cost, water is preferable.

The polymerization initiator for the acrylamide polymer is not particularly limited as long as it is soluble in a solvent. Examples thereof include azo compounds such as 2,2'-azobis-2-amidinopropane hydrochloride, azobisisobutyronitrile, and 2,2'-azobis-2,4-dimethylvaleronitrile. In addition, peroxides such as ammonium persulfate, potassium persulfate, hydrogen peroxide, ammonium peroxodisulfate, benzoyl peroxide, lauroyl peroxide, succinic peroxide, octanoyl peroxide, t-butylperoxy 2-ethylhexanoate The system is raised. Further, a redox system in which ammonium peroxodisulfate is combined with sodium sulfite, sodium hydrogen sulfite, tetramethylethylenediamine, trimethylamine, or the like can be given.

The temperature and time of the polymerization reaction of the acrylamide polymer are not particularly limited as long as the obtained acrylamide polymer has an intrinsic viscosity of 12.5 to 28 dl / g and an anionization degree of 0.05 meq / g or less. By gradually raising the temperature from a low temperature, an acrylamide polymer that satisfies the above conditions can be polymerized. If the starting temperature is too high, the intrinsic viscosity decreases, and a hydrolyzate of acrylamide is generated during the reaction to increase the degree of anionization. Therefore, a lower starting temperature is better. More specifically, the starting temperature is preferably 10 ° C. to 30 ° C., more preferably 15 ° C. to 25 ° C., and further preferably 18 ° C. to 22 ° C. In addition, the upper limit of the temperature that rises after the start of polymerization is preferably 80 ° C. or less, more preferably 70 ° C. or less, and even more preferably 65 ° C. or less in that it is easy to control heat generation during polymerization. .

<Method for producing paper additive>
By subjecting the acrylamide polymer contained in the intermediate of the papermaking additive to the Hofmann decomposition reaction, it is possible to produce a papermaking additive having a sufficient yield improvement effect and drainage improvement effect in a well-balanced manner.

When performing the Hofmann decomposition reaction, a solution obtained by polymerization reaction of an acrylamide polymer may be used as it is, or may be diluted. Moreover, you may prepare a solution separately as needed.

If the concentration of the acrylamide polymer used for the Hofmann decomposition reaction is set high, the reaction becomes heterogeneous, and a sufficient yield improvement effect, drainage improvement effect, and paper strength improvement effect cannot be obtained. In order to obtain these effects sufficiently, the concentration of the acrylamide polymer is preferably 2% by mass or less. More preferably, it is 1.5 mass% or less, More preferably, it is 1 mass% or less. Further, if the concentration of the acrylamide polymer is too low, the efficiency of the Hoffman decomposition reaction is deteriorated, so that it is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.00. 1% by mass or more.

The Hofmann decomposition reaction is carried out by allowing hypohalous acid to act on the amide group of the acrylamide polymer under alkaline conditions. The Hoffmann decomposition reaction can be carried out in a specific pH range of 11-14. In order to make it alkaline conditions, alkali metal hydroxides, such as sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. are used, for example. Moreover, in order to make hypohalous acid act, hypohalites, such as a hypochlorite, a hypobromite, a hypoiodite, are used, for example.

Examples of hypochlorite, hypobromite, and hypoiodite include alkali metal salts or alkaline earth metal salts thereof. Examples of the alkali metal of hypochlorous acid include sodium hypochlorite, potassium hypochlorite, and lithium hypochlorite.

The amount of hypohalite used for the Hofmann decomposition reaction is not particularly limited, but if the amount of the acrylamide polymer relative to the hypohalite is too small or too large, the amount of the acrylamide polymer that is not subjected to the reaction or Since the amount of halite increases, the efficiency of the reaction decreases. In order to carry out the reaction efficiently, the molar ratio of hypohalite to acrylamide polymer is preferably 1:10 to 10:10, more preferably 2.5: 10 to 10:10, Preferably, it is 5:10 to 10:10.

The reaction in the Hofmann decomposition reaction is possible at a temperature of 0 to 110 ° C. Regarding the combination of reaction temperature and reaction time, if the temperature is low or the time is too short, the reaction becomes insufficient, and if the temperature is too high or the time is too long, an undesirable side reaction may occur. . Therefore, in order to prevent such a situation and perform the reaction efficiently, for example, the reaction temperature and reaction time of 10 ° C. to 40 ° C. for 30 to 60 minutes or the temperature of 50 to 80 ° C. for 10 seconds to 10 minutes. The Hofmann decomposition reaction may be performed in combination.

The reaction can be stopped by adding a reducing agent such as strong acid such as hydrochloric acid, sulfuric acid or nitric acid, sodium sulfite, sodium thiosulfate, ethyl malonate, triethylamine or thioglycerol. The reaction can also be stopped by diluting with a large amount of water or cooling to low temperature.

The paper produced by adding the paper additive thus obtained has excellent properties balanced in drainage, yield, and paper strength.

In the papermaking process, the papermaking additive of the present invention and a conventional papermaking additive may be used in combination.

<Method of evaluating drainage yield improvement effect>
Evaluation of the drainage yield improvement effect is carried out by first using 100% used paper 1% corrugated pulp slurry as a slurry, and a CSF (Canadian Standard Freeness) value of 450 ml. Next, a chemical addition rate (vs. corrugated cardboard SS) is added so as to be 500 ppm, and stirred at 800 rpm for 10 seconds. Thereafter, the drainage, sheet moisture (press dewaterability) and yield are evaluated. Freeness is evaluated by the CSF measurement method. The sheet moisture (press dewaterability) is measured by DDA (Dynamic Drainage Analyzer: manufactured by AB Akribiki Kemikonsulter). The yield is measured by DFS (Dynamic Filtration System: manufactured by Mutek).

<Method of evaluating paper strength improvement effect>
Evaluation of the paper strength improvement effect is first made in accordance with JISP8209, using a papermaking additive with an LBKP (Hardwood Bleached Kraft Pulp) slurry and various papermaking additives, using hand-made round handmade sheet machine. At that time, handmade paper is prepared so as to have a basis weight of 120 g / m ² . The basis weight is measured by the method specified in JIS P 8124. The paper strength improvement effect is evaluated by measuring the specific burst strength and short span of the prepared handmade paper. The specific burst strength is a numerical value obtained by dividing the burst strength of paper expressed in kilopascal (kPa) by the basis weight. The short span (specific compressive strength) refers to a value obtained by dividing the maximum load when the span of a test piece to which a load is applied is shortened (0.7 mm) and compressed and broken by the basis weight. The specific burst strength is measured according to JIS P8112. Further, the short span of the prepared handmade paper is measured according to JIS P 8156.

<Example> (Polymer A)
To a four-necked flask equipped with a stirrer and a temperature sensor, 198 g of acrylamide (AAM) powder and 793 g of ion-exchanged water were added, and the monomer weight was adjusted to 20% of the whole and the total weight was 990 g. Next, the temperature was adjusted to 20 ° C. and nitrogen substitution was performed. Add 1 ml of ammonium persulfate 0.1% aqueous solution and 0.3 g of 2,2 'azobis-2-amidinopropane hydrochloride aqueous solution to the prepared solution, and continue to purge with nitrogen. After about 5 minutes, polymerization starts. It was done. The temperature gradually increased to about 65 ° C., and the polymerization was completed in 5 hours.

During the polymerization, the contents became highly viscous and stirring became difficult, so stirring was stopped halfway. After the polymerization was completed, the contents were taken out. The intrinsic viscosity of this polymer was about 14.8 dl / g. Further, a nonionic polymer having an anionization degree of 0.01 meq / g and a very high purity could be obtained. The intrinsic viscosity was calculated by measuring the flow time using a Canon Fenceke viscometer and using the Huggins equation and the Mead-Fuoss equation from the measured values. The degree of anionization was measured by the method described in paragraph 0029 of JP-A-2009-228162.

<Comparative Example 1> (Polymer B)
A four-necked flask equipped with a stirrer and a temperature sensor was charged with 71 g of acrylamide, and water was added to make a total amount of 443.8 g. Polymerization was initiated by adding 0.22 g of ammonium persulfate and 0.1 g of sodium bisulfite. The temperature was kept at 85 ° C., and the reaction was terminated after 2 hours. As a result, a polymer having a polymer concentration of 15% and an intrinsic viscosity of 7.9 dl / g was obtained. Moreover, the hydrolyzate of acrylamide produced | generated at the time of reaction, and the anionization degree was 0.11 meq / g. (Refer to the polymerization method of Comparative Example 1 described in Patent Document 1)

<Comparative Example 2> (Polymer C)
In a four-necked flask equipped with a stirrer and a temperature sensor, 70.93 g of acrylamide and 0.154 g of methylenebisacrylamide were charged, 0.22 g of ammonium persulfate and 0.1 g of sodium hydrogen sulfite were added to initiate polymerization. The temperature was kept at 85 ° C., and the reaction was terminated after 2 hours. As a result, a polymer having a polymer concentration of 15% and an intrinsic viscosity of 5.5 dl / g was obtained. An acrylamide hydrolyzate was produced during the reaction, and the anionization degree was 0.12 meq / g. (Refer to the polymerization method of Example 1 described in Patent Document 1)

<Hoffmann decomposition reaction>
The acrylamide polymers obtained in Examples and Comparative Examples 1 and 2 were first diluted to 1% by mass or less. Next, heating was performed, and sodium hypochlorite and caustic soda were added to react. The reaction was stopped with hydrochloric acid. The reaction conditions are shown in Table 1.

<Evaluation of drainage yield improvement effect>
As a slurry, a 1% corrugated cardboard pulp slurry made of 100% waste paper was used, and the CSF (Canadian Standard Freeness) value was 450 ml. The chemical addition rate (vs. corrugated cardboard SS) was added to 500 ppm and stirred at 800 rpm for 10 seconds. Thereafter, a measurement test was performed. Evaluation was performed by the CSF measurement method. Sheet moisture was measured by DDA. Yield was measured by DFS. The results are shown in Table 2.

<Evaluation of paper strength improvement effect>
Evaluation of the paper strength improvement effect was carried out in accordance with JISP8209. First, handmade paper was prepared by a Wangken type round handmade sheet machine using various papermaking additives in the LBKP slurry. At that time, handmade paper was prepared so as to have a basis weight of 120 g / m ² . The basis weight was measured by the method specified in JIS P 8124. The specific burst strength of the handmade paper was measured according to JIS P8112. Further, the short span of the handmade paper was measured according to JIS P 8156. The results are shown in Table 3.

Based on the above results, it can be confirmed that the polymers of Examples 1 to 4 can perform the Hoffman reaction at any temperature of room temperature, 60 ° C., and 70 ° C., and can achieve a certain degree of modification. It was. These polymers were confirmed to be excellent in all of drainage, press dewaterability (sheet moisture), yield, and paper strength. Although the polymers of Comparative Examples 1 and 2 are excellent in paper strength, the molecular weight is low or the spread of the molecules is reduced by crosslinking, so the drainage, press dewaterability (sheet moisture), and the yield are insufficient. I understood that. The normal C-PAM of Comparative Example 5 was excellent in both drainage and yield, but showed a tendency to decrease the press dewaterability of the wet paper, and the paper strength was low. Polyethyleneimine and polyethyleneamine were excellent in freeness and press dewaterability, but the paper strength was low. In particular, polyethyleneimine had a low yield. C-PAM was excellent in drainage and yield, but low in press dewaterability and paper strength. Therefore, it was found that only Examples 1 to 4 were excellent in balance in all properties. In Examples 1 to 4, since the DDA pressure was lower than those in Comparative Examples 1 to 4 and 6, it was confirmed that the sheet had good resistance (breathability), and the value of Comparative Example 5 was about 217 lower. From this, it was confirmed that the uniformity of the sheet was maintained.

Claims

An intermediate for a paper additive containing an acrylamide polymer having an intrinsic viscosity of 12.5 to 28 dl / g and an anionization degree of 0.05 meq / g or less.
The intermediate of the papermaking additive according to claim 1, wherein no crosslinking agent is added in the polymerization reaction step for producing the acrylamide polymer.
A method for producing a paper additive, comprising a step of subjecting the intermediate of the paper additive according to claim 1 or 2 to a Hofmann decomposition reaction.
The method for producing an additive for papermaking according to claim 3, wherein in the Hofmann decomposition reaction, the acrylamide polymer is subjected to the reaction as a solution of 2% by mass or less.