JPH05140896A - Additive for paper making - Google Patents

Abstract

PURPOSE:To obtain the subject additive containing a specific (meth)acrylamide based copolymer being low viscosity and excellent in paper strength enhancing effect and workability and useful for reclamation of waste paper, etc. CONSTITUTION:The objective additive containing a copolymer obtained by copolymerizing (A) (meth)acrylamide, preferably of 70-96mol% with (B) an anionic vinyl monomer such as acrylic acid, (C) one or more kinds of monomers selected from cationic vinyl monomers such as dimethylaminoethyl (meth) acrylate, preferably of 2-15mol%, (D) a vinyl monomer having a polyalkylene glycol group such as polyethylene glycol mono(meth)acrylate or polypropylene glycol mono(meth)acrylate, preferably of 0.5-20mol% and as necessary (E) a nonionic vinyl monomer other than the above-mentioned monomers, (e.g. acrylonitrile), preferably of <=20mol% and (F) a cross-linkable copolymer, preferably of 0.05-2.0mol%.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a papermaking additive. More specifically, it relates to a papermaking additive containing a (meth) acrylamide-based copolymer having a highly branched structure.

[0002]

2. Description of the Related Art In recent years, papermaking additives, especially paper strength enhancers, have been regarded as important in the production of paper and paperboard. The reasons for this are that the use of good quality pulp was restricted due to the deterioration of the situation of supply of raw wood, and the need to reuse used paper was further strengthened for the purpose of energy saving and resource saving. However, papermaking additives as paperboard modifiers have become even more indispensable.

On the other hand, for the purpose of improving the productivity with the speeding up of paper machines, or improving the quality according to the diversification of paper, the dependence on the drainage improver and the paper strength enhancer and the range of use thereof are further increased. It is widespread. Under these circumstances, polyacrylamide-based additives have become the mainstream as additives for papermaking.

Polyacrylamide-based papermaking additives are anionic type and cation (including amphoteric) depending on ionicity.
It can be classified into types. For example, as the anion type, a copolymer of acrylamide and an anionic vinyl monomer, α, β-unsaturated monocarboxylic acid or α, β-unsaturated dicarboxylic acid, or partial hydrolysis of an acrylamide copolymer Things are known. On the other hand, as the cation (amphoteric) type, there are a modified type and a copolymerized type based on the difference in the method of introducing the ionic functional group. For example, modified types include Hoffmann rearranged products of Mannich, mannich modified products, and the like, while copolymerized types include cationic vinyl monomers and (meth) acrylamides, and if necessary anionic vinyl monomers. Alternatively, various copolymers prepared by copolymerizing other non-polymerizable vinyl monomers are known (JP-A-60-94697).

However, in recent years, the use conditions of the papermaking additives have become more and more severe, so that in the conventionally known relatively low molecular weight polyacrylamide-based papermaking additives,
It has reached the limit in terms of its effect as an additive. for that reason,
A means of increasing the molecular weight is adopted to improve performance,
If the polymer is simply made to have a high molecular weight, the resulting copolymer has an excessively high viscosity, which results in poor dispersibility during papermaking. As a result, when such a copolymer is used as a papermaking additive, excessive cohesion occurs, and the texture of the papermaking is apt to be disturbed.

In order to solve this problem, attempts have been made to give a branched structure by using a cross-linking agent to increase the molecular weight of the resulting copolymer while suppressing the increase in viscosity thereof. The reactivity of the crosslinking agent is insufficient, and it is difficult to introduce a uniform branched structure. Further, a copolymer obtained by using a vinyl monomer having a hydroxyalkyl group in combination with a crosslinking agent has also been proposed, but its effect as an additive for papermaking is not yet sufficient (JP-A-2-13949).
No. 4).

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a papermaking additive containing a high molecular weight (meth) acrylamide copolymer and having a relatively low viscosity.

[0008]

As a result of intensive studies to solve the above-mentioned problems of the prior art, the present inventors have found that a method for producing a (meth) acrylamide copolymer having a branched structure by adding a crosslinking agent. In the case of using a vinyl monomer having a polyalkylene glycol group as a copolymerization component, a high molecular weight (meth) acrylamide copolymer can be obtained without increasing the viscosity.
Moreover, they have found that the copolymer is excellent in various effects as an additive for papermaking, and have completed the present invention.

That is, the present invention has (A) acrylamide and / or methacrylamide, and at least one selected from (B) anionic vinyl monomer and (C) cationic vinyl monomer, and (D) polyalkylene glycol group. The present invention relates to a paper-making additive containing a vinyl monomer, (E) a nonionic vinyl monomer other than the above, and (F) a copolymer obtained by copolymerizing a crosslinkable vinyl monomer.

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

Examples of the anionic vinyl monomer as the component (B) include monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid and muconic acid; vinylsulfonic acid. , Styrenesulfonic acid, organic sulfonic acids such as 2-acrylamido-2-methylpropanesulfonic acid; or sodium salts and potassium salts of these various organic acids, and these can be used alone or in combination of two or more. ..

Typical examples of the cationic vinyl monomer as the component (C) include dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth).
Vinyl monomers having a tertiary amino group such as acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, allylamine, diallylamine, or triallylamine, or their inorganic or organic acids such as hydrochloric acid, sulfuric acid, and acetic acid. Or a vinyl monomer containing a quaternary ammonium salt obtained by reacting the tertiary amino group-containing vinyl monomer with a quaternizing agent such as methyl chloride, benzyl chloride, dimethylsulfate and epichlorohydrin. These can be used alone or in combination of two or more.

In the present invention, it is essential to use a vinyl monomer having a polyalkylene glycol group as the component (D). As the polyalkylene glycol group,
Any compound having at least two repeating units of oxyalkylene groups may be used, and it is preferable to use up to about 10 repeating units. That is, this component is intended to introduce more branched structures into the copolymer obtained by utilizing the fact that there are a plurality of chain transfer points derived from oxyalkylene groups in the molecule. Specific examples of the component (D) include polyethylene glycol mono (meth) acrylates such as diethylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate, and polypropylene glycol mono as described above. (Meth) acrylate, methoxy polyethylene glycol mono (meth) acrylate, polytrimethylene glycol mono (meth) acrylate, polytetramethylene glycol mono (meth) acrylate, polyethylene glycol propylene glycol mono (meth) acrylate and the like can be mentioned.

The nonionic vinyl monomer (E) which is an optional monomer component is an alkyl ester of the anionic vinyl monomer (B) (having 1 to 1 carbon atoms of the alkyl group).
8), acrylonitrile, styrene, vinyl acetate, methyl vinyl ether and the like.

The following are typical examples of the crosslinkable vinyl monomer as the component (F). For example, as the bifunctional vinyl monomer, di (meth) acrylates such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate and triethylene glycol di (meth) acrylate, methylenebis (meth) acrylamide, ethylenebis (Meth) acrylamide, bis (meth) acrylamides such as hexamethylenebis (meth) acrylamide, divinyl adipate, divinyl sebacate and other divinyl esters, allyl methacrylate, epoxy acrylates, urethane acrylates, N-methylol acrylamide, Examples thereof include diallylamine, diallyldimethylammonium, diallyl phthalate, diallyl chlorendate and divinylbenzene. Further, as the trifunctional monomer, 1,3,5-triacryloylhexahydro-S-triazine, triallyl isocyanurate, triallylamine, triallyl trimellitate, N, N-
Examples of tetrafunctional vinyl monomers such as diallyl acrylamide are tetramethylolmethane tetraacrylate, tetraallyl pyromellitate, N, N, N ′, N ′.
-Tetraallyl-1,4-diaminobutane, tetraallylamine salt, tetraallyloxyethane and the like. These may be used alone or in combination of two or more. Among these, it is preferable to use a compound having a double bond as all the functional groups because the reaction can be easily controlled during production.

In the present invention, the amount of each of the components (A) to (F) used must be determined in consideration of the performance of the resulting copolymer as a papermaking additive. That is,
The component (A) is usually about 60 to 98 mol%, preferably 70 to 96 mol% based on the total molar sum of the components (A) to (F).
Similarly, the components (B) and (C) are usually about 1 to 20 mol%, preferably 2 to 15 mol%, and must contain at least one component. Similarly, the component (E) is usually about 25 mol% or less, preferably 20 mol% or less. When each of the above components is out of the above range, a sufficient paper strengthening effect cannot be obtained in any case. Similarly, the component (F) is usually about 0.01 to 5 mol%,
Preferably it is 0.05 to 2.0 mol%. 0.01
When it is less than 5 mol%, a sufficient branched structure cannot be obtained, and when it exceeds 5 mol%, the copolymer obtained is insoluble in water, which is not preferable.

Further, the amount of the component (D) used in the present invention has an important influence on the performance of the resulting copolymer as a paper-making additive, and therefore must be carefully determined. Usually, it is usually about 0.1 to 20 mol%, preferably 0.5 with respect to the total molar sum of components (A) to (F).
It is set in the range of 10 to 10 mol%. If the amount is less than 0.1 mol%, the number of branch points due to the chain transfer effect is small, the branch structure is insufficient or non-uniform, and the improvement of the effect as a papermaking additive is hardly recognized. If it exceeds, the chain transfer effect becomes too large and a large amount of low molecular weight products are produced, and in some cases, the polymerization reaction does not proceed sufficiently, which is not preferable.

The copolymer used in the present invention can be synthesized by various conventionally known methods. For example, the above-mentioned various monomers ((A) to (F) components) and water are charged into a predetermined reaction vessel, and a persulfate such as potassium persulfate or ammonium persulfate, or a reducing agent such as sodium bisulfite is added. The desired water-soluble (meth) acrylamide-based copolymer can be obtained by adding an ordinary radical polymerization initiator such as a redox-based polymerization initiator in a combined form and heating with stirring.

The thus obtained copolymer has a higher branching than the conventionally known cross-linking type acrylamide copolymer obtained by simply using the cross-linkable vinyl monomer by using the component (D). It has a structure. for that reason,
The copolymer of the present invention usually has a weight average molecular weight of 2,000,000 to 1
Even when the polymer has a high molecular weight of about 10 million, the viscosity is the same as that of a conventionally known cross-linking acrylamide copolymer, and the solid content is converted to 15% by weight at 15,000 c.
It can be used with properties below ps.

[0020]

The papermaking additive containing the (meth) acrylamide copolymer having a high molecular weight and a highly branched structure according to the present invention has many contacts between pulp fibers and is used for papermaking such as paper strength enhancing effect. It exhibits various characteristic performances as an additive. As a result, it exhibits various excellent effects as a papermaking additive even under recent severe papermaking conditions. In addition, it has a relatively low viscosity despite its high molecular weight copolymer and is excellent in workability.

[0021]

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

Example 1 81 parts of acrylamide, 80%, in a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube.
Acrylic acid aqueous solution 6 parts, dimethylaminoethyl methacrylate 10 parts, diethylene glycol monomethacrylate 4 parts, triallyl isocyanurate 0.3 parts and ion-exchanged water 370 parts were charged, and oxygen in the reaction system was removed through nitrogen gas. .. Next, the inside of the system was heated 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 raising the temperature to 85 ° C., the temperature was kept for 2 hours. After the completion of the polymerization, 186 parts of ion-exchanged water was added, pH 4.2 and solid content 15.1
%, A copolymer solution having a viscosity (25 ° C.) of 9400 cps was obtained. Table 2 shows the property values of the resulting branched copolymer aqueous solution.
Shown in.

Examples 2 to 5 and Comparative Examples 1 to 6 In Example 1, except that at least one of the types of components (A) to (F) or the amount thereof used was 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 each of the obtained copolymer aqueous solutions.
Shown in.

[0024]

[Table 1]

[0025]

[Table 2]

(Performance Evaluation Method 1) Waste corrugated paper was beaten with a Niagara type beater and 1.6% of sulfuric acid band was added to pulp adjusted to 420 ml of Canadian Standard Freeness (CSF). To pH 5.5,
Then, each copolymer aqueous solution obtained in each of the above Examples and Comparative Examples was added with 0.6% of pulp as a paper strengthening agent,
After stirring, dilute the pulp slurry concentration to 0.1% and use a tapping sheet machine to weigh 150 g / m 2.
^The paper was made to have a weight of 2 and press dehydrated at 5 Kg / cm ² for 2 minutes. Then, it was dried in a rotary dryer at 105 ° C. for 3 minutes and then dried at 20 ° C. and 65% R.A. H. After conditioning the humidity for 24 hours under the conditions of, the specific burst strength was measured according to JIS P 8112. The results are shown in Table 3.

(Performance Evaluation Method 2) BKP was beaten with a Niagara type beater, and pulp (pH 6.8) adjusted to (CSF) 550 ml was obtained from each of the above Examples and Comparative Examples. Add an aqueous copolymer solution as above,
The same operation as above was performed to measure the specific burst strength. The results are shown in Table 3.

[0028]

[Table 3]

From the results shown in Tables 2 and 3, the (mer) acrylamide-based copolymer obtained by the present invention has a high molecular weight as compared with the conventional product, but has substantially the same viscosity and excellent paper. It is recognized that the strength-enhancing effect is exhibited.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroro Saikai 3-4-3 Imafuku Minami, Joto-ku, Osaka Arakawa Chemical Industry Co., Ltd.

Claims (3)

[Claims] 1. A vinyl monomer having (A) acrylamide and / or methacrylamide, at least one selected from (B) anionic vinyl monomer and (C) cationic vinyl monomer, and (D) a polyalkylene glycol group-containing monomer. (E) a papermaking additive containing a copolymer obtained by copolymerizing (E) a nonionic vinyl monomer other than the above, and (F) a crosslinkable vinyl monomer. 2. The papermaking additive according to claim 1, wherein the component (D) is polyethylene glycol mono (meth) acrylate or polypropylene glycol mono (meth) acrylate. 3. The amount of the component (D) used is from (A) to
The papermaking additive according to claim 1, which is 0.5 to 20 mol% of the total molar sum of the component (F).