JPH08188982A - Additive for papeermaking - Google Patents

Abstract

PURPOSE: To obtain a new additive for papermaking, having high aluminum ion addition effect with a small amount, exhibiting paper strength enhancing effect in neutral paper making using a small amount of a aluminum sulfate. CONSTITUTION: This additive for neutral papermaking comprises an ampholytic polyacrylamide based polymer containing both a cationic group and an anionic group obtained by bonding aluminum ion. The viscosity of the ampholytic polyacrylamide-based polymer is preferably 500-15,000cps in a 15% aqueous solution. An aluminum compound to supply an aluminum ion in an aqueous solution is added and mixed during polymerization of the ampholytic polyacrylamide-based polymer or after the polymerization.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a papermaking additive, and more specifically, an acrylamide system in which aluminum ions are electrically bonded so as to more effectively exert a chemical effect by being added to a papermaking system having a small band usage. The present invention relates to a papermaking additive containing a copolymer as a main component.

[0002]

2. Description of the Related Art In recent years, the papermaking industry has become more and more dependent on waste paper due to the circumstances of raw materials, and on the other hand, there is a tendency for wastewater to be treated closed due to social demands for environmental protection. Under such circumstances, the paper strength of paper tends to decrease, and various papermaking additives are indispensable for suppressing the decrease in paper strength and maintaining the quality of paper. Current,
Acrylamide-based polymer (PA
M) is the mainstream, and various improvements have been made so far in terms of composition and polymer structure. In terms of composition, they are classified into anion type, cation type, and amphoteric type.
Methods of introducing ionic groups into this type of PAM include a copolymerization type obtained by copolymerizing various ionic monomers with acrylamide and a modified type obtained by a Hoffmann degradation product or Mannich modified product of PAM. From that, pH
A variety of products with an ionic composition that matches each papermaking condition, such as the amount of paper and the amount of band used, is selected and applied.

However, the amount of bands used in neutral papermaking systems, which has been increasing recently, is low due to the filler, and the bands are added separately from the polymer. Also,
Under such conditions of high pH use, the aluminum ion undergoes a morphological change, its cationicity decreases (inactivates), and the ionic interaction through the band does not work sufficiently. It is at a lower level than acidic systems.

In order to make up for such drawbacks, in addition to ionic improvement, the molecular structure of the polymer has been improved, and PA has been improved.
Due to the high molecular weight and cross-linking of M, the mechanism other than ionic adsorption works to improve the polymer yield and paper strength effect and stabilize the effect (JP-A-2-61197).
Issue, Ibid. 4-18190, Id. 3-227482, Id. 3-227483, Id. 5-2709
2, ibid 5-287693, ibid 5-140893, ibid 6-41898).

[0005]

However, in order to obtain a product having the target physical properties by the above method, an increase in cost due to the use of special chemicals is unavoidable, or the control of the polymerization conditions is complicated, and fluctuations occur. There are problems such as occurrence. In addition, the deterioration of the papermaking environment as described above is progressing.

[0006] Therefore, as a result of intensive studies so that the aluminum ion can be added without changing the morphology of the aluminum ion under the neutral papermaking condition in which the band is used in a small amount, the aluminum ion is mixed with the anionic PAM. Then, thickening is large and it cannot be used as an additive for papermaking due to gelation, but when mixed with amphoteric PAM, ionic crosslinking between aluminum ion and anionic property proceeds,
It was found that the polymer thickens to some extent, but gelation is suppressed by the presence of cationic groups, and the polymer can be used as an additive for papermaking. Moreover, it was discovered that the function of strengthening paper strength as amphoteric PAM and aluminum ions does not deteriorate.

Therefore, it is an object of the present invention to provide a novel papermaking additive which has a large effect of adding aluminum ions and exhibits a paper strength-enhancing effect in a small amount of neutral papermaking using a small amount of sulfuric acid band. To do.

[0008]

The present invention resides in an additive for neutral papermaking, which comprises an amphoteric polyacrylamide polymer having a cationic group and an anionic group as a main component, to which aluminum ions are bound.

Examples of acrylamides used to obtain the copolymerization type polyacrylamide polymer in the present invention include acrylamide and methacrylamide, as well as N-methyl acrylamide, N-ethyl acrylamide, N, N-dimethyl acrylamide and N. Examples include water-soluble N-substituted lower alkyl acrylamides such as isopropyl acrylamide and diacetone acrylamide, and these may be used alone or in combination of two or more.

As the monomer to be copolymerized with acrylamides, nonionic monomers as well as ionic monomers having anions and cations can be applied. Examples of the anionic monomer include monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid and muconic acid, and salts thereof. In addition, organic sulfonic acids such as vinyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and salts thereof can be used, but a carboxylic acid system having a strong interaction with an aluminum compound. It is preferably used in combination with a monomer.

Examples of the cationic monomer include tertiary amine monomers such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, allylamine and diallylamine. Alternatively, salts of inorganic or organic acids such as hydrochloric acid, sulfuric acid, acetic acid, etc., or tertiary amine type monomers with methyl chloride, benzyl chloride, dimethyl sulfate,
Examples thereof include ammonium salt-based monomers which are quaternized by a reaction with epichlorohydrin and the like. These ionic monomers may be used alone or in combination of two or more.

The nonionic monomer can be used in an amount that does not impair the water solubility of the polymer, and examples thereof include (meth) acrylonitrile, styrene and vinyl acetate.

It is also possible to use small amounts of crosslinkers in the polymerization of the copolymers according to the invention. Examples of the cross-linking agent include bis (meth) bis (meta) acrylamide such as methylenebis (meth) acrylamide, ethylenebis (meth) acrylamide, bis (meth) acrylamide-methylolethyleneurea condensate, and bis (meth) acrylamide-methylolurea.
Di (meth) acrylates such as acrylamides, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, divinyl adipate, divinyl sebacate, etc., N,
Examples thereof include trivinyl monomer-based crosslinking agents such as N-diallyl acrylamide, 1,2,3-triacroylhexahydro-S-triazine and triallyl isocyanurate. The addition amount of these crosslinking agents is 0.005-1
Optimally, it is 0.01 to 0.2 mol% in terms of mol%.

The method for polymerizing the amphoteric polyacrylamide copolymer according to the present invention can be carried out by various conventionally known methods. For example, the above-mentioned various monomers and water are charged into a predetermined reaction vessel, and a persulfate such as potassium persulfate or ammonium persulfate, or a usual redox-based polymerization initiator such as a combination thereof with a reducing agent such as sodium bisulfite is used. A desired polymer can be obtained by adding a radical polymerization initiator or an azo-based polymerization initiator, and optionally using a chain transfer agent such as isopropyl alcohol or allyl alcohol as appropriate and heating with stirring. .

The resulting amphoteric polyacrylamide polymer is a 15% aqueous solution and has a viscosity of 100 to 20,0 as measured by a Brookfield viscometer at 25 ° C.
Although it is 00 cps, normally 500 to 10,000 cps is used. Further, the amphoteric polyacrylamide polymer used in the present invention may be a mixture of one kind or two or more kinds of copolymers having different compositions.

Any aluminum compound can be used in the present invention as long as it is water-soluble and forms aluminum ions, aluminum aqua complex ions and the like. Examples of the aluminum compound include polyaluminum chloride, alumina sol, polyaluminum sulfate, polysulfate aluminum silicate, aluminum chloride, aluminum sulfate, alum and the like.
These aluminum compounds may be used alone or in combination of two or more. In particular, aluminum sulfate is preferable in terms of handling and cost.

The aluminum compound may be added to the above amphoteric PAM at the time before the polymerization or the polymer during and after the polymerization, but it is added after the polymerization for the sake of easy control of the viscosity of the product. Is the best.
Therefore, the present invention is to add and mix an aluminum compound that supplies aluminum ions in an aqueous solution during or after the polymerization of an amphoteric polyacrylamide polymer having a cationic group and an anionic group formed by binding aluminum ions. It also provides a method for producing a characteristic neutral papermaking additive.

If the aluminum compound is mixed in an amount greater than the required amount, the viscosity increases and gelation may occur depending on the combination with the polymer, or the effect may decrease due to a decrease in the effective components of the polymer. preferable. The addition amount of the aluminum compound varies depending on the composition of the polymer, the concentration and the kind of the aluminum compound, but is generally in the range of 0.05 to 7 mol% as Al ions relative to the polymer solid content, preferably 0.1 to It is 4 mol%.

Since the polymer is thickened by the addition of the aluminum compound, the polymer is diluted so that the gelation does not proceed partially, and the mixture is gradually added dropwise while stirring. The viscosity of the 15% aqueous polymer solution of the final product of the amphoteric PAM to which aluminum ions are bound is 300 to 30,000 cps as measured by Gluckfield viscometer at 25 ° C., but is usually in the range of 500 to 15,000 cps. Preferably there is.

The polymer obtained by the present invention exerts a higher effect under the papermaking conditions where the amount of band used is small and the sufficient chemical effect cannot be obtained conventionally. For example, the amount of band added to the pulp slurry is effective under papermaking conditions in the range of 0% to 2%, and more preferably the amount of band is 0%.
The pH is in the range of 7.5 to 5.3 at 1%. Therefore, in the present invention, papermaking is carried out by adding an additive for neutral papermaking whose main component is an amphoteric polyacrylamide polymer having a cationic group and an anionic group obtained by binding aluminum ions under neutral papermaking conditions. It is intended to provide a papermaking method.

[0021]

[Function] Since any amphoteric PAM is thickened by mixing the aluminum compound, the aluminum ion formed from the added aluminum compound is aqua complex ion [Al.
It is speculated that ionic bond or cross-linking is progressing due to the traction effect that charges the ions of the anionic dissociative group of amphoteric PAM mutually in the form of (H ₂ O) ₆ ] ³⁺ and the like. . It is considered that this bonding or cross-linking structure caused the spread of the polymer and the change of the molecular weight, and the structural factor was improved. In addition, since some of the aluminum compounds remain in the polymer with aluminum-like properties that remain active even under high pH conditions, ionic effects similar to those of the bands also work effectively, and excellent effects are achieved even under low band usage conditions. It seems to work.

[0022]

Therefore, according to the present invention, the conventionally used sulfuric acid band is different from the activated form of aluminum ion at the time of papermaking, and the amphoteric PA obtained in the examples is obtained.
It can be seen that the specific burst strength of the paper made from M is increased by an average of 9% or more as compared with that of the polymer S of the comparative example in which aluminum complex ions are not bound. On the other hand, when the same type of aluminum compound that forms aluminum complex ions is added at the time of papermaking (referred to as separate addition), the strength is not significantly different from that of the comparative polymer S, which is far from the effect of the present invention. That is, the effect of the present invention cannot be obtained by simply adding the aluminum compound separately. Therefore, amphoteric PA is produced under the low band papermaking conditions where it was difficult to obtain the chemical effect of adding aluminum ions.
The effects of adding both M and aluminum ions are more efficiently exhibited than the conventional chemicals.

[0019]

EXAMPLES The present invention will be described in more detail with reference to examples. Examples of the present invention will be shown below, but the present invention is not limited to these examples. Various polyacrylamide-based copolymers used as paper strengthening agents in Examples and Comparative Examples were prepared as follows. In the following,% is% by weight unless otherwise specified.

Comparative Example 1 In a 1-liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube, water 523 g, 40% acrylamide 314.1 g, dimethylaminoethyl methacrylate 12.0 g, 80% 5.1 g of acrylic acid and 2.0 g of isopropyl alcohol are charged, and the pH is adjusted to around 3.0 with acid or alkali.
Nitrogen gas was passed through the reaction system to remove oxygen. Then, the temperature was raised to 55 ° C. with stirring, and 10 g of a 5% ammonium persulfate solution and 5 g of 2.5% sodium sulfite were added as a polymerization initiator to initiate polymerization. After that, 85 ℃
The temperature was maintained for 2 hours to complete the polymerization. Nonvolatile content 16.4
%, Viscosity 2500 cps, pH 4.1, this polymer is abbreviated as S-1.

Comparative Example 2 In a 1-liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube, 561 g of water, 304.0 g of 40% acrylamide, 34.6 g of dimethylaminopropylacrylamide, and itaconic acid were placed. Charge 7.4 g and isopropyl alcohol 2 g, and adjust with acid or alkali so that the pH will be around 3.0. Nitrogen gas was passed through the reaction system to remove oxygen. Then, the temperature was raised to 55 ° C. with stirring, and 10 g of a 5% ammonium persulfate solution and 5% of 2.5% sodium sulfite were used as a polymerization initiator.
g was added to initiate polymerization. Then, the temperature was maintained at 85 ° C. for 2 hours to complete the polymerization. Nonvolatile content 16.3%, viscosity 1
This polymer having a constant number of 800 cps and pH 4.2 is abbreviated as S-2A.

A 1-liter four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube was charged with water 514.
g, 40% acrylamide 311.0 g, dimethylaminopropyl acrylamide 14.8 g, acrylic acid 8.
Charge 6 g and isopropyl alcohol 2 g, p
Adjust with acid or alkali so that H becomes around 3.0. Nitrogen gas was passed through the reaction system to remove oxygen. Then, the temperature was raised to 55 ° C. with stirring, and 10 g of a 5% ammonium persulfate solution and 5 g of 2.5% sodium sulfite were added as a polymerization initiator to initiate polymerization. afterwards,
Polymerization was terminated by holding at 85 ° C for 2 hours. Nonvolatile content 1
This polymer having a constant of 6.5%, viscosity of 2200 cps and pH 4.1 is abbreviated as S-2B.

Two polymers obtained (S-2A, B)
And a non-volatile content of 16.5.
%, Viscosity 2900 cps, pH 4.2, this polymer is abbreviated as P-2.

Tables below are obtained in the same manner as in the above comparative example.
The base polymers S-3 to S-7 are prepared by using a monomer composition corresponding to the composition shown in Example 1 and using an appropriate catalyst amount.
I got The polymer constants obtained are shown in Table 1.

[0025]

[Table 1]

Example 1 A 500 ml four-necked flask equipped with a stirrer and a thermometer was charged with 500 g of the polymer (S-1) obtained in Comparative Example 1. 40 g of an aluminum sulfate (Al content is 1.8 wt%) aqueous solution diluted to a concentration of 20% is added dropwise to the stirred polymer. Nonvolatile content 15.3%, viscosity 8500 cps, p
This polymer having a constant of H3.7 is abbreviated as P-1.

Example 2 A 500 ml four-necked flask equipped with a stirrer and a thermometer is charged with 500 g of the polymer (S-1) obtained in Comparative Example 1. 16 g of an aluminum sulfate (Al content is 1.8 wt%) aqueous solution diluted to a concentration of 20% is added dropwise to the stirred polymer. Nonvolatile content 15.6%, viscosity 6900 cps, p
This polymer having a constant of H3.9 is abbreviated as P-2.

The following is a table in the same manner as in the above embodiment.
Various aluminum compounds were mixed with the base polymers S-3 to S-7 shown in 1 to obtain polymers P-3 to P-7.
The constants of the obtained polymer are shown in Table 2.

[0029]

[Table 2] Abbreviations of monomers in the table are as follows. AM: Acrylamide MAM: Methacrylamide AA: Acrylic acid IA: Itaconic acid FA: Fumaric acid MA: Maleic acid DM: Dimethylaminoethyl methacrylate DM-Q: DM chloride quaternary DM-BQ: DM benzyl chloride quaternary Compound DMAPAA: Dimethylaminopropylacrylamide DMAPAA-Q: Methyl chloride quaternary product of DMAPAA DMAPAA-BQ: Benzyl chloride quaternary product of DMAPAA

Evaluation method 1 BKP was beaten with a Niagara type beater, and Canadian Standard Freeness (CSF) 380 m
A sulfuric acid band was added to the pulp adjusted to 1 to 0.5% by weight with respect to the pulp to adjust the pH to 6.5. Furthermore, the polymer obtained in each of the above Comparative Examples and Examples was added to 0.4% by weight of pulp.
Is added. The obtained pulp slurry is made into a sheet having a basis weight of 80 g / m ² using a square sheet machine and 5 kg.
/ M ² was pressed for 1 minute and further dried at 105 ° C. for 3 minutes to prepare a test paper. Furthermore, at 20 ° C. and 65% R.
After conditioning the humidity for 24 hours under the condition of H, JIS P 811
According to 2, the specific burst strength was measured. The results are shown in Table 3.

[0031]

[Table 3]

The relationship between the specific burst strength of paper and the amount of aluminum compound added by the papermaking additive obtained in the examples of the present invention and the comparison between the strength in the examples and that of the comparative example without addition of the aluminum compound were compared. As shown in FIG.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the amount of aluminum compound added and the specific burst strength of paper.

FIG. 2 is a diagram showing the influence of the type and addition amount of an aluminum compound on the specific burst strength of paper.

FIG. 3 is a diagram showing the relationship between the presence or absence of addition of an aluminum compound and the specific burst strength.

[Explanation of symbols]

 None

Claims (8)

[Claims] 1. An aluminum ion bonded,
An additive for neutral papermaking, which comprises an amphoteric polyacrylamide polymer having a cationic group and an anionic group as a main component. 2. An amphoteric polyacrylamide polymer is 1
The additive according to claim 1, wherein the seed or the mixture is a mixture of two or more copolymers having different compositions. 3. The additive according to claim 1, wherein the aluminum ion bonded to the amphoteric polyacrylamide polymer is 0.05 mol% to 7 mol% based on the polymer in terms of ion. 4. An aqueous solution of a 15% amphoteric polyacrylamide polymer having a cationic group and an anionic group bonded with aluminum ions and having a viscosity of 500 to 1500.
Neutral papermaking additive with 0 cps. 5. An additive for neutral papermaking, which comprises adding and mixing an aluminum compound which supplies aluminum ions during or after the polymerization of an amphoteric polyacrylamide polymer having a cationic group and an anionic group. Method of manufacturing agent. 6. The method according to claim 5, wherein the aluminum compound is added as Al ions in an amount of 0.05 to 7 mol%, preferably 0.1 to 4 mol%, based on the polymer solids. 7. The method according to claim 5, wherein the aluminum compound is aluminum sulfate. 8. Paper making by adding a neutral papermaking additive containing as a main component an amphoteric polyacrylamide polymer having a cationic group and an anionic group, which are formed by binding aluminum ions under neutral papermaking conditions. A papermaking method characterized by: