JP2979741B2 - Manufacturing method of papermaking additives - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing an amphoteric acrylamide copolymer having a branched structure useful as a papermaking additive.

[0002]

2. Description of the Related Art In recent years, papermaking additives, in particular, paper strength agents, have been regarded as important in the production of paper and paperboard. This is due to the fact that the use of real pulp was restricted due to the worsening log supply situation, and the necessity of reusing waste paper for the purpose of energy saving and effective use of resources was further strengthened. Thus, papermaking additives as modifiers for paper and paperboard have become even more indispensable.

[0003] On the other hand, for the purpose of improving productivity due to speeding up of a paper machine or improving quality in accordance with diversification of paper, the dependence on a drainage improver and a paper strength enhancer and the range of use thereof are further increased. Is widespread. Under such circumstances, polyacrylamide-based additives have become the mainstream as papermaking additives.

Polyacrylamide-based papermaking additives are anionic and cationic (including amphoteric) depending on ionicity.
Can be classified into types. For example, the anion type includes acrylamide and an α, β-unsaturated monocarboxylic acid, which is a vinyl monomer having an anion group, or α, β.
-Copolymerization with unsaturated dicarboxylic acids or partial hydrolysates of polyacrylamide copolymers are known. On the other hand, as the cationic (amphoteric) type, there are a modified type and a copolymerized type based on the difference in the method of introducing an ionic functional group. For example, as a modified type,
There are a Hoffman rearranged product and a Mannich modified product of a polyacrylamide copolymer. On the other hand, as the copolymerization type, a vinyl monomer having a cationic group and (meth) acrylamide, and if necessary, an anionic vinyl monomer or other Nonionic vinyl monomer capable of copolymerization
Are known (JP-A-60-94697).

[0005] However, in recent years, the use conditions of papermaking additives have become more and more severe, and therefore, conventionally known relatively low molecular weight polyacrylamide-based papermaking additives have
It has reached its limit in terms of its effect as an additive. for that reason,
Means of increasing the molecular weight are taken to improve the performance,
When the molecular weight is simply increased, the viscosity of the obtained copolymer is excessively increased, so that the dispersibility at the time of papermaking becomes poor. As a result, when such a copolymer is used as a papermaking additive, excessive coagulation occurs, and the formation of the formed paper tends to be disordered.

In order to solve this problem, attempts have been made to increase the molecular weight of the resulting copolymer while suppressing the rise in viscosity by using a crosslinking agent to impart a branched structure. When a polyfunctional vinyl monomer was used, its effect as a papermaking additive was not yet sufficient because the reactivity of the polyfunctional vinyl monomer was insufficient or it was difficult to introduce a uniform branched structure. .

[0007]

The inventors of the present invention have conducted intensive studies to solve these problems, and as a result, have found that a conventional amphoteric acrylamide polymer having a linear structure can be reacted with a specific crosslinking agent. It has been found that a desired branched structure can be more easily introduced, and a papermaking additive having excellent various effects can be obtained. The present invention has been completed based on such findings.

That is, the present invention provides:
(A) acrylamide and / or methacrylamide, (B) a vinyl monomer having a cationic group copolymerizable with the component (A), (C) a vinyl monomer having an anionic group copolymerizable with the component (A), And (D) a water-soluble copolymer obtained by copolymerizing a nonionic monomer copolymerizable with the above-mentioned component (A), if necessary, and (E) a polyfunctional epoxy compound with each monomer of the copolymer. The present invention relates to a method for producing an additive for papermaking, characterized in that a crosslinking reaction is carried out in such a proportion that the amount of the polyfunctional epoxy compound (E) used is 0.1 to 2 mol% with respect to the total amount of the components.

In the present invention, acrylamide or methacrylamide as the component (A) can be used alone or in combination, but from the viewpoint of economy, acrylamide is preferably used alone.

Typical examples of the cationic monomer (B) include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, and the like. Or a vinyl monomer having a tertiary amino group such as diethylaminopropyl (meth) acrylamide
Or a salt of an inorganic or organic acid such as hydrochloric acid, sulfuric acid, or acetic acid, or a reaction of the tertiary amino group-containing vinyl monomer with a quaternizing agent such as methyl chloride, benzyl chloride, dimethyl sulfate, or epichlorohydrin. And a vinyl monomer containing a quaternary ammonium base.

The component (C) as the anionic monomer includes, for example, monocarboxylic acids such as acrylic acid and methacrylic acid; dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid; vinyl sulfonic acid and styrene sulfone Organic sulfonic acids such as acids; and sodium salts and potassium salts of these various organic acids.

If desired, it is also possible to introduce, besides the above-mentioned constituent monomers, any monomers copolymerizable therewith. Examples of the optional monomer component (D) include esters of alcohol having 1 to 8 carbon atoms with acrylic acid or methacrylic acid, and nonionic monomers such as acrylonitrile, styrene, vinyl acetate and methyl vinyl ether. No.

The polyfunctional epoxy compound as the component (E) used in the present invention can be used without any particular limitation as long as it is water-soluble and has two or more epoxy groups in the molecule. Representative examples of the component (E) include various known components such as (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, (poly) glycerin diglycidyl ether, and (poly) glycerin triglycidyl ether. Things can be mentioned.

A feature of the present invention is to provide a branched amphoteric acrylamide copolymer obtained by crosslinking a linear amphoteric acrylamide copolymer which is effective as a papermaking additive with the component (E). However, in the production of the amphoteric acrylamide copolymer, a polyfunctional vinyl monomer may be used in combination without departing from the scope of the present invention. Examples of the polyfunctional vinyl monomer include ethylene glycol di (meth) acrylate, diethylene glycol
Di (meth) acrylates such as rudi (meth) acrylate and triethylene glycol di (meth) acrylate;
Methylenebis (meth) acrylamide, ethylenebis (meth) acrylamide, hexamethylenebis (meth)
Bis (meth) acrylamides such as acrylamide, divinyl esters such as divinyl adipate and divinyl sebacate, allyl methacrylate, epoxy acrylate
Difunctional benzenes, urethane acrylates, divinylbenzene, glycidyl (meth) acrylate and other bifunctional vinyl monomers; 1,3,5-triacryloylhexahydro-S
-Triazine, triallyl isocyanurate, N, N-
Trifunctional vinyl monomers such as diallyl acrylamide;
Examples include tetrafunctional vinyl monomers such as tetramethylol methane tetraacrylate and tetraallyl pyromellitate.

In the present invention, the amount of each of the components (A) to (D) must be determined in due consideration of the performance of the obtained copolymer as a papermaking additive. Range. That is, the component (A) is usually 98 to 60 mol%, preferably 96 to 70 mol%, based on the total mol of the components (A), (B), (C) and (D); 1 to 20 mol%, preferably 2
Component (C) is also 1 to 20 mol%, preferably 2 to 15 mol%; Component (D) is also 25 mol% or less, preferably 20 mol% or less. Therefore,
Outside this range, a sufficient paper strength enhancing effect cannot be obtained in any case.

Furthermore, the amount of the component (E) used in the present invention has the most important effect on the performance of the obtained copolymer as a papermaking additive, and therefore must be determined particularly carefully. Usually, the amount of component (E) used is in the range of 0.1 to 2 mol%, preferably 0.2 to 1.5 mol%, based on the total amount of each monomer component of the water-soluble copolymer before crosslinking. It is said. When the amount is less than 0.1 mol%, the branched structure is insufficient, and the effect as a papermaking additive, for example, the improvement of the effect by crosslinking is almost recognized as compared with the paper strength enhancing effect of the copolymer before crosslinking. Not preferred. On the other hand, if it exceeds 2 mol%, the degree of crosslinking of the resulting cross-linked copolymer becomes too high, so that the clay becomes too high, the water-solubility decreases, and in some cases, the water-insoluble is preferable. Absent.

The copolymer used in the present invention before the cross-linking reaction can be synthesized by various conventionally known methods. For example, the above-mentioned various monomers are stored in a predetermined reaction vessel.
(Components (A) to (D)) and water are charged, and a persulfate such as potassium persulfate or ammonium persulfate, or a redox polymerization initiator in the form of a combination of these with a reducing agent such as sodium bisulfite is used. A normal radical polymerization initiator is added, and if necessary, a chain transfer agent such as isopropyl alcohol and allyl alcohol is appropriately used,
The desired water-soluble and amphoteric acrylamide copolymer can be obtained by heating under stirring. The viscosity of the obtained copolymer is usually preferably not more than about 15,000 cps in terms of workability in terms of solid content concentration of 15% by weight.

Next, the amphoteric acrylamide copolymer before crosslinking obtained above and the component (E) are simultaneously charged at the above-mentioned predetermined ratio, respectively, or the component (E) is divided or gradually charged, and sufficient Usually 40 to 9 under stirring conditions
The reaction may be performed at about 0 ° C. for 0.5 to 3 hours. Under such conditions, a papermaking additive having a relatively low viscosity despite being a polymer can be easily obtained.

The branched and amphoteric acrylamide copolymer of the present invention obtained as described above can exert excellent effects as a papermaking additive even under recent severe papermaking conditions. In addition, although it is not clear why the papermaking additive of the present invention exerts such an excellent effect, since the resulting polymer has a uniform and high branched structure,
It is presumed that the number of contact points between pulp fibers increases, and as a result, various characteristic performances as papermaking additives are exhibited.

[0019]

By using the specific branched copolymer obtained according to the present invention as an additive for papermaking, it can be used as an additive for papermaking which is more excellent than a linear copolymer before the crosslinking reaction. , Especially the effect of enhancing paper strength and excellent workability. Further, as compared with a conventional partially crosslinked polymer made of a polyfunctional vinyl monomer, there is a great effect that a papermaking additive, which is a branched acrylamide copolymer, can be provided more easily.

In the present invention, it is essential that the above-mentioned component (E) is applied to the amphoteric acrylamide copolymer to cause crosslinking, but naturally, an anionic acrylamide copolymer or a cationic acrylamide copolymer is required. By similarly crosslinking the copolymer with the component (E), a desired branched structure can be introduced. However, the effect as a papermaking additive, particularly the effect of enhancing paper strength, is inferior to the branched amphoteric acrylamide copolymer obtained in the present invention.

[0021]

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

Example 1 A four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube was charged with 60 parts of acrylamide, 80%
4 parts of an aqueous solution of acrylic acid, 7 parts of dimethylaminoethyl methacrylate and 280 parts of ion-exchanged water were charged, and oxygen in the reaction system was removed through nitrogen gas. Next, the temperature in the system was adjusted to 40 ° C., and 0.25 part of ammonium persulfate and 0.15 part of sodium hydrogen sulfite were added as a polymerization initiator with stirring. After the temperature was raised to 85 ° C., the temperature was kept for 2 hours. After completion of the polymerization, 115 parts of ion-exchanged water was added, and
An aqueous copolymer solution having a 5.2% viscosity (25 ° C.) of 4000 cps was obtained. Then, 0.8 parts of ethylene glycol diglycidyl ether was added to the aqueous copolymer solution at a time, and a crosslinking reaction was performed at 70 ° C. for 1 hour. Table 2 shows the property values of the obtained branched copolymer aqueous solution.

Examples 2 to 8 and Comparative Examples 1 to 5 In Example 1, at least one of the types of the components (A) to (D) and the component (E) and the amount used thereof is shown in Table 1. Except for the above, the same operation as in Example 1 was performed to obtain an aqueous copolymer solution. Table 1 shows the composition of each aqueous copolymer solution obtained in each Example and Comparative Example, and Table 2 shows property values.

[0024] In the table, AM: acrylamide DM: dimethylaminoethyl methacrylate DMAPAM: dimethylaminopropyl acrylamide DMC: methacryloyloxytrimethylammonium chloride AA: acrylic acid IA: itaconic acid AN: acrylonitrile BA: butyl acrylate TAF: 1,3,5-tri Acryloyl hexahydro-
S-Triazine EGDGE: Ethylene glycol diglycidyl ether GTGE: Glycerin tridiglycidyl ether. The amount of the component (E) used is represented by mol% based on the total amount of the components (A) to (D).

[0025]

(Performance Evaluation Method 1) Recycled corrugated paper was beaten with a Niagara beater to obtain Canadian Standard.
1.6% sulfuric acid band was added to pulp adjusted to 420 ml of de-freeness (CSF) to pH 5.5,
Then, 0.6% of pulp was added to each aqueous solution of the copolymer obtained in each of the above Examples and Comparative Examples as a paper strength enhancer.
After stirring, the mixture was diluted to a pulp slurry concentration of 0.1%, dewatered with a tappy sheet machine, pressed at 5 kg for 2 minutes, and paper-made to a basis weight of 150 g / m ² . Then, it is dried at 105 ° C. for 3 minutes in a rotary dryer, and is dried at 20 ° C. and 65% R.C. H. After conditioning for 24 hours under the above conditions, the specific burst strength was measured according to JIS P8112. Table 3 shows the results. (Performance Evaluation Method 2) BKP was beaten with a Niagara beater, and (CSF) pulp (pH 6.8) adjusted to 550 ml was used to obtain each copolymer obtained in the above Examples and Comparative Examples. The aqueous solution was added in the same manner as above, and the same operation as above was performed to measure the specific burst strength. Table 3 shows the results.

[0027]

From the results shown in Table 3, it can be seen that the branched amphoteric acrylamide copolymer obtained by the method of the present invention has a relatively low viscosity as compared with the conventional product, and furthermore exhibits an excellent paper strength enhancing effect. Is recognized.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) D21H 17/52 C08F 8/08 D21H 17/41-17/45

Claims (2)

(57) [Claims] (A) acrylamide and / or methacrylamide; (B) a vinyl monomer having a cationic group copolymerizable with the component (A); and (C) an anionic group copolymerizable with the component (A). (D) a water-soluble copolymer obtained by copolymerizing a nonionic monomer copolymerizable with the component (A), if necessary, and (E) a polyfunctional epoxy compound. A method for producing a papermaking additive, wherein a crosslinking reaction is carried out in such a proportion that the amount of the polyfunctional epoxy compound (E) used is 0.1 to 2 mol% with respect to the total amount of each monomer component of the polymer. 2. The method for producing a papermaking additive according to claim 1, wherein the reaction temperature between the water-soluble copolymer and the component (E) is 40 to 90 ° C.