JP3089747B2 - 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 method for producing an acrylamide copolymer having a branched structure useful as an additive for papermaking.

[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 deterioration of log supply, 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, as the anion type, α, β-unsaturated monocarboxylic acid, which is a vinyl monomer having acrylamide and an anionic 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 Hoffmann rearrangement products and Mannich modified products of polyacrylamide copolymers, while copolymerization types include vinyl monomers having a cationic group and (meth) acrylamide, and vinyl monomers having an anionic group or other monomers as required. Various copolymers obtained by copolymerizing a nonionic vinyl monomer which can be copolymerized with the above 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, the effect as a papermaking additive was not yet sufficient because the reactivity of the polyfunctional vinyl monomer was insufficient or a uniform branched structure was difficult to introduce. .

[0007]

The inventors of the present invention have made intensive studies to solve these problems, and as a result, have found that a conventional 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.

[0008]

That is, the present invention provides:
(A) acrylamide and / or methacrylamide, (B) a vinyl monomer having an anionic group copolymerizable with the above component (A), and (C) a cationic group copolymerizable with the above component (A) if necessary. And (D) a water-soluble copolymer obtained by copolymerizing at least one selected from nonionic vinyl monomers copolymerizable with the component (A), and (E) a polyfunctional aziridinyl compound. (E) a cross-linking reaction at a ratio of the amount of the polyfunctional aziridinyl compound of 0.001 to 1 mol% with respect to the total molar amount of each monomer component of the copolymer; According to the manufacturing method.

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

(B) Examples of the vinyl monomer having an anionic group include: monocarboxylic acids such as acrylic acid and methacrylic acid; dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid; and organic acids such as vinylsulfonic acid and styrenesulfonic acid. Sulfonic acid; or sodium salts and potassium salts of these various organic acids. The component (B) is an essential component in the water-soluble copolymer because it serves as a crosslinking reaction point with the polyfunctional aziridinyl compound (E).

In the present invention, the water-soluble copolymer can be made into an amphoteric acrylamide copolymer by using a vinyl monomer having a cationic group (C), if desired. Can be improved. As the component (C), for example, a vinyl monomer having a tertiary amino group such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, or diethylaminopropyl (meth) acrylamide Or a salt of an inorganic or organic acid such as hydrochloric acid, sulfuric acid or acetic acid, or a reaction between the tertiary amino group-containing vinyl monomer and a quaternizing agent such as methyl chloride, benzyl chloride, dimethyl sulfate or epichlorohydrin. And a vinyl monomer containing a quaternary ammonium base.

Further, in addition to the above monomers, (D) a nonionic vinyl monomer copolymerizable therewith can also be used. Examples of the component (D) include esters of an alcohol having 1 to 8 carbon atoms and acrylic acid or methacrylic acid, acrylonitrile, styrene, vinyl acetate, methyl vinyl ether, and the like.

The polyfunctional aziridinyl compound (E) used in the present invention is water-soluble and contains 2
Any compound having at least two aziridinyl groups can be used without any particular limitation. As the component (E), for example, tetramethylolmethane-tri-β-aziridinylpropionate, trimethylolpropane-tri-
β-aziridinylpropionate, 4,4′-bis (ethyleneiminocarbonylamino) diphenylmethane and the like.

The feature of the present invention is that the component (A) and the component (B)
A linear anionic or amphoteric acrylamide copolymer effective as a papermaking additive, obtained by copolymerizing at least one component selected from the components and, if necessary, the components (C) and (D), It is an object of the present invention to provide a branched acrylamide copolymer obtained by crosslinking with the component (E), but a polyfunctional vinyl monomer may be used for producing the acrylamide copolymer within a range not departing from the present invention. Can be used together. Examples of the polyfunctional vinyl monomer include di (meth) acrylates such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and triethylene glycol di (meth) acrylate; methylene bis (meth) acrylamide; Meth) acrylamide,
Bis (meth) acrylamides such as hexamethylenebis (meth) acrylamide; divinyl esters such as divinyl adipate and divinyl sebacate; allyl methacrylate, epoxy acrylates, urethane acrylates, divinyl benzene, glycidyl (meth) acrylate and the like Bifunctional vinyl monomers; Trifunctional vinyl monomers such as 1,3,5-triacryloylhexahydro-S-triazine, triallyl isocyanurate, N, N-diallylacrylamide; tetramethylolmethanetetraacrylate, tetraallylpyromelli And tetrafunctional vinyl monomers such as tate.

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 about 98 to 60 mol%, preferably 96 to 70 mol%, based on the total mole of the components (A), (B), (C) and (D).
Mol%; similarly, the component (B) is usually about 2 to 40 mol%,
Preferably it is 2 to 15 mol%. Similarly, the component (C) is usually about 20 mol% or less, preferably 15 mol% or less.
Mol% or less; Similarly, the component (D) is usually about 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 with particular care. Usually, 0.001 to 1 based on the total molar amount of each monomer component of the water-soluble copolymer before crosslinking.
Mol%, preferably in the range of 0.01 to 0.5 mol%. When the amount is less than 0.001 mol%, the branched structure is insufficient and the effect as a papermaking additive, for example, the improvement in 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 1 mol%, the resulting cross-linked copolymer will have too high a degree of cross-linking, so that the viscosity will be too high, the water solubility will be reduced, or in some cases it will be water-insoluble. Absent.

The synthesis of the copolymer before the crosslinking reaction used in the present invention can be carried out by various conventionally known methods. For example, the above various monomers (components (A) to (D)) and water are charged into a predetermined reaction vessel, and a persulfate such as potassium persulfate or ammonium persulfate, or a combination thereof with a reducing agent such as sodium hydrogen sulfite. A normal radical polymerization initiator such as a redox polymerization initiator in the form of a mixture 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. It is preferable that the viscosity of the obtained copolymer is usually about 15,000 cps or less in terms of workability in terms of a solid concentration of 15% by weight.

Then, the anionic or 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. The reaction may be usually performed at about 40 to 90 ° C. for 0.5 to 2 hours under sufficient stirring conditions. Under such conditions, a papermaking additive having a relatively low viscosity despite being a polymer can be easily obtained.

The branched acrylamide copolymer of the present invention obtained as described above can exhibit 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 exhibits such an excellent effect, since the produced polymer has a uniform and high branched structure, the number of contacts between pulp fibers increases, As a result, it is presumed that various characteristic performances as papermaking additives are exhibited.

[0020]

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. In addition, compared with the conventional partially crosslinked polymer having a polyfunctional vinyl monomer, there is a great effect that a papermaking additive, which is a branched acrylamide copolymer, can be provided more easily.

[0021]

The present invention will now be described more specifically with reference to examples and comparative examples. Both parts and% are
Unless otherwise specified, 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 210 parts of acrylamide (3.
0 mol), 14.8 parts of an 80% aqueous solution of acrylic acid (0.1
6 mol), dimethylaminoethyl methacrylate25.
7 parts (0.16 mol), 1086 parts of ion-exchanged water, 50
% Sulfuric acid was charged, and oxygen in the reaction system was removed through nitrogen gas. Next, the temperature in the system was raised to 40 ° C., 0.3 parts of ammonium persulfate and 0.125 part of sodium bisulfite were added as a polymerization initiator with stirring, the temperature was raised to 70 ° C., and the temperature was kept for 2 hours. After the completion of the polymerization, 280 parts of ion-exchanged water are charged, and the solid content is 15.2%, and the viscosity (25 ° C)
Of 12,000 cps. Then
Tetramethylolmethane-tri-β was added to the aqueous copolymer solution.
0.42 parts of aziridinyl propionate (0.03 mol% based on the total moles of all charged monomers) was added at a time, and a crosslinking reaction was carried out at 70 ° C. for 1 hour. Table 2 shows the property values of the obtained branched copolymer aqueous solution.

Examples 2 to 6 and Comparative Examples 1 to 3 In Example 1, at least one of the types of the components (A) to (D) and the component (E) and the amount used thereof was used.
Except that the seeds were changed as shown in Table 1, the same operation as in Example 1 was performed to obtain an aqueous copolymer solution. Table 2 shows the property values of the obtained aqueous copolymer solutions.

Comparative Example 4 In Example 1, 0.33 parts of 1,3,5-triacryloylhexahydro-S-triazine (0.04 mol% based on the total molar amount of all charged monomers) was used. The same operation as in Example 1 was performed except that an aqueous polymer solution was produced, and the subsequent operation was not performed. Table 2 shows the property values of the obtained aqueous copolymer solutions.

[0025]

[Table 1]

In the table, AM: acrylamide, DM: dimethylaminoethyl methacrylate, DMAPAA: dimethylaminopropyl acrylamide, DMC: methacryloyloxyethyltrimethylammonium chloride, A
A: acrylic acid, IA: itaconic acid, AN: acrylonitrile, BA: butyl acrylate, TMMTAP: tetramethylolmethane-tri-β-aziridinylpropionate, TMPTAP: trimethylolpropane-tri-β-aziridinylpro Indicates pionate. In addition,
The use amount of the component (E) indicates mol% based on the total molar amount of the components (A) to (D).

[0027]

[Table 2]

(Performance Evaluation Method 1) Waste cardboard was beaten with a Niagara beater, and 1.6% of a sulfuric acid band was added to pulp adjusted to 420 ml of Canadian Standard Freeness (CSF) to obtain a pH of 5.5. 5 and
Then, the aqueous solution of each copolymer obtained in each of the above Examples and Comparative Examples was added as a paper strength enhancer to 0.6% of pulp, and the mixture was stirred and diluted to a pulp slurry concentration of 0.1%. Dehydrate with tappi sheet machine, 2 at 5Kg
The paper was then pressed to obtain a 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 pulp (pH 6.8) adjusted to 550 ml of (CSF) was added to each pulp obtained in each of the above Examples and Comparative Examples. An aqueous copolymer solution was added as described above,
The same operation as above was performed to measure the specific burst strength. Table 3 shows the results.

[0030]

[Table 3]

From the results shown in Table 3, it is recognized that the branched 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. Can be

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) D21H 17/00-27/42

Claims (2)

(57) [Claims] (A) acrylamide and / or methacrylamide, (B) a vinyl monomer having an anionic group copolymerizable with the component (A), and optionally (C) a component (A). A water-soluble copolymer obtained by copolymerizing at least one selected from a vinyl monomer having a polymerizable cationic group and (D) a nonionic vinyl monomer copolymerizable with the component (A); The cross-linking reaction of the functional aziridinyl compound is carried out in such a ratio that the amount of the polyfunctional aziridinyl compound used is 0.001 to 1 mol% with respect to the total molar amount of each monomer component of the copolymer. Manufacturing method of papermaking additives. 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.