JPS5921798A - Aqueous filterability enhancing and dry paper strength increasing agent of paper - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a dry paper strength enhancer for internal addition, which improves the furnace water properties during the production of paper and paperboard, and is made of a water-soluble multi-component copolymer containing acrylamide or methacrylamide as a main component. Regarding.

The supply situation for raw wood, the raw material for paper, is only getting worse.
Converting to hardwood materials, increasing the proportion of waste paper used, and increasing pulp yields are important issues. Therefore, the amount of fine fibers in the papermaking raw material inevitably increases, and the papermaking conditions deteriorate accordingly. In addition, as part of environmental measures, closed pulp, paper, and paperboard manufacturing processes are becoming inevitable, and as a result, papermaking conditions such as rising water temperatures and deteriorating water quality are becoming increasingly worse. This has a major impact on the performance of chemicals used.

Conventionally, anionic polyacrylamide resins have been widely used as paper strength enhancers in paper manufacturing processes. □ However, such anionic acrylamide resins require sulfuric acid as a fixing agent, so they are limited to use in acidic environments, causing problems with drainage, corrosion of paper machines, and poor paper strength due to low fixation rates. There are problems such as insufficient
Particularly in recent times, where paper-making conditions have deteriorated, it has become impossible to achieve sufficient functionality.

Although cationic paper strength and reinforcing agents that do not require fixing agents such as '-1/ζ and sulfuric acid have been developed, for example, polyamide polyamine resins such as those shown in Japanese Patent Publication No. 3'5-3547, Although it contributes to the direction of force, it tends to foam during paper making, and since the molecular weight cannot be increased, it has disadvantages such as poor furnace water resistance. On the other hand, cationic paper strength enhancers such as copolymers of acrylamide and dimethylamine ethyl methacrylate have been developed and are effective over a wide pH range, but the paper strength obtained is still insufficient. It's hard to say that.

Furthermore, conventional paper strength enhancing agents, whether anionic or cationic, have a serious drawback in that they cannot sufficiently improve the compressive strength particularly required for paperboard.

Since corrugated cardboard is stacked for protection, storage, or transportation of contents, it is required to have higher compressive strength, such as Ring Claso 7 strength, than typical bursting strength or tensile strength. However, since the compressive strength of paper and general paper strength are not necessarily proportional, it has been difficult to produce paper with sufficiently excellent compressive strength only by using conventional paper strength enhancers.

In an attempt to increase the compressive strength, conventional techniques have proposed the use of a cationic polymer compound and an anionic polymer compound in combination. According to this, a relatively high compressive strength can be obtained, but the waste paper content ratio The current situation is that the effectiveness of chemicals is becoming insufficient under recent papermaking conditions that have deteriorated due to an increase in wastewater and closed drainage systems.

On the other hand, in papermaking processes such as paperboard, reactor water propensity 2 agents are used for fast reactor water as machines run at higher speeds.

Conventionally, reactor water properties improvers include those with a molecular weight of at most 10,000 or less, such as polyethyleneimine, but with very high cationic properties, or cationic polymers with a very high molecular weight (more than 3 million), especially polyacrylamide. Mannich compound or acrylamide-dimethylamine ethyl methacrylate copolymer is used. Since these reactor water properties improvers have extremely high molecular weights, if used in large amounts, they will cause poor formation. In addition, the anionic polyacrylamide resin used to strengthen the strength of paperboard generally has a low molecular weight of 200,000 to 300,000, so even if a sulfuric acid band is used as a fixing agent, the effect of reactor water resistance is low. Because they are rarely shown, many paperboard manufacturing processes use furnace water property improvers in conjunction with anionic polyacrylamide resins.

The present inventors have achieved the functions of conventional paper strength enhancers and reactor water properties improvers with a single agent in the paper and paperboard manufacturing process, and furthermore,
With the aim of obtaining a paper strength enhancer that can provide excellent compressive strength that is not found in known paper strength enhancers, we have conducted intensive research and found that 50 to 97 mol% of acrylamide, 3 to 30% of N-methylol acrylamide, After copolymerizing 0 to 20 molar groups of acrylonitrile or methacrylonitrile in an aqueous medium, all or part of the methylol groups in the resulting copolymer, at least 50 molar groups, are primary. A deionized aqueous solution (pH 9, temperature 20°C) of a Mannich base and Shida copolymer in amine and a concentration of
) has a viscosity of 1. It has been discovered that a water-soluble copolymer having a molecular weight in the range of 0 to 200,000 centipoise can achieve all of the above objects, and the present invention has now been completed.

The present invention will be explained in more detail below. : The copolymer of the present invention has (1) acrylamide 50 9 fumol ratio represented by the formula CH, = CHCONH2; (n)
2CH2=C) (CON Hc I(, OH)
(N-methylol acrylamide 3-50-
e/l='%;(m)<CH2==C-CN(RHzk
;4eJ'T"-F:' or methyl group) acrylonitrinyl or methacrylonide 4
At least 50 moles of the methylol groups in the copolymer having 0 to 20 moles of methylol as constituent monomers are converted into Mann-Ninohi bases with secondary amines,
It is a high molecular weight water-soluble resin with a weight average molecular weight in the range of approximately 500,000 to 3,000,000.

There is no particular restriction on the method of polymerizing the above monomer mixture to obtain a copolymer, and any conventional known polymerization method may be used. As a polymerization method, aqueous solution polymerization is generally used, but reverse phase emulsion polymerization, reverse phase emulsion polymerization, precipitation polymerization, etc. can also be used.

General methods for aqueous solution polymerization include persulfates such as potassium persulfate and ammonium persulfate, peroxides such as hydrogen peroxide, or redox initiators using these and reducing agents;
An initiator such as an azo compound such as azobisamidinopropane hydrochloride, azobisin butyronitrile, or a combination of an azo compound with a reducing agent such as sodium sulfite is added to the monomer mixture from o, 01 to 2 parts by weight, an aqueous solution having a monomer concentration of 5 to 50 parts by weight, heated to 20 to 100 DEG C. under a nitrogen atmosphere, and polymerized for 1 to 10 hours. Further, in this case, a pH adjuster such as an acid or a base, or a chain transfer agent such as impropatol or jetanolamine may be added. Furthermore, if necessary, it can be obtained and handled as a powder by heat drying or precipitation treatment with an organic solvent.

The copolymer thus obtained is then reacted with a secondary amine to convert the methylol groups in the copolymer into Mannich bases, imparting cationic properties.

The secondary amine used in this reaction is preferably a lower alkylamine, particularly dimethylamine, but cyclic amines such as /chlorohexylamine or lower alkanolamines such as jetanolamine can also be used. It is not necessary that all of the methylol groups in the copolymer be Mannich bases, and only some may be used, but if there are too few, the degree of cationization will be low, and the fixation to the pulp will be poor, making it difficult to expect a sufficient effect to be expressed. Therefore, it is desirable that at least 50 moles or more, preferably 80 moles or more of the methylol groups in the copolymer be converted into Mannich bases. Note that when the degree of cationization of the copolymer resin is too high, the cohesive force is too strong, which tends to result in poor formation of paper, resulting in poor paper strength and poor paper formability. Since the amount of the constituent monomer (11) containing a methylol group in the polymer does not exceed 50 moles, there is no problem even if all of it is converted into a Mannich base. Therefore, the secondary amine used in the reaction is usually 05 to 14 mol per mol of N-methylolacrylamide component, and the reaction is usually carried out at 20 to 70°C for about 05 to 10 hours.

Polyacrylamide Mannich compound, which is commonly used as an amphoteric paper strength enhancer, has a molecular weight of about 10,000 to 200,000, and this is made by polymerizing polyacrylamide using formalin and dimethylamine. Obtained by Mannich reaction. However, the polymer prepared by this method has a high molecular weight, and even if the polymer has a similar viscosity in an aqueous solution, the polymer of the present invention has almost no effect on improving reactor water properties, improving ring lash strength, and increasing paper strength. It does not swell and has strong cohesiveness, resulting in poor formation.

Although the reason for this is not well understood, it is presumed that the distribution of cationic groups in the polymer chain is different. The product obtained by polymerizing the above polyacrylamide and then carrying out the Mannich reaction using formalin and dimethylamine may not be neutralized after the reaction is complete, or even if it has been neutralized to pH 6 or less with sulfuric acid, hydrochloric acid, or acetic acid. When the molecular weight is about 1 million and the viscosity is about 8.000'Cps in a 5% aqueous solution, it tends to gel during the reaction and has poor storage stability at 30°C, making it difficult to use.

However, like the polymer of the present invention, acrylamide and N
Copolymerization of methylol acrylamide and subsequent reaction with dimethylamine does not cause any gelation during the reaction, has very good storage stability at 30°C, and is stable for about 1 month or more. It was recognized that there were significant differences.

The viscosity of the copolymer of the present invention in a deionized aqueous solution is an extremely important factor in obtaining the effects of the present invention. ) is 1.000~200. OOO
It is necessary to be in the range of c p s.

If the viscosity is less than 1.000 cps, sufficient effects will not be exhibited; If OOOcps is exceeded, the cohesive force is too strong, resulting in poor formation, poor paper strength, and poor paper-making properties. Preferably, the range is from 2.000 to 100,000 cps.

The cationic polymer of the present invention can be used according to a conventionally known method, and can be used in the paper/board making process with or without sulfuric acid band, for example, at a rate of 0.00
2~tswt%, preferably 0.1~0.7w
By adding approximately t%, the reactor water resistance can be greatly increased, and at the same time, the paper strength such as ring crush strength and bursting strength can be improved.

A feature of the paper strength enhancer of the present invention is that it can improve the furnace water properties in the papermaking process and at the same time impart excellent compressive strength (ring flanginess strength) to paper.

Although known paper strength enhancers cannot significantly improve the compressive strength of the resulting paper even if they are used in large amounts,
The paper strength agent of the present invention can improve compressive strength when used in a small amount.

The molecular weight (molding average molecular weight) of the cationic copolymer of the present invention is in the range of approximately 500,000 to 3,000,000, which is extremely higher than the anionic polyacrylamide resin conventionally used as a paper strength agent. On the other hand, the molecular weight on the lid is lower than that of cationic polymers used as reactor water quality improvers.

Example 1 1) Production Example A 50% aqueous solution of ac-jylamide 1407 and N-methylol acrylamide 301 were placed in a flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet, and the total amount was brought to 19602 with deionized water. shall be.

The temperature of the solution was maintained at 40°C and heated with nitrogen gas for approximately I Hr.
Aerate and add 2% ammonium persulfate (+
201, triethanolamine 20% aqueous solution 10
1. Add 1 aqueous solution of azobisamidinopronotan hydrochloride
og-addition to initiate polymerization.

The temperature of the solution rises to about 50°C due to the heat of polymerization,
The reaction was continued for 8 hours. After the reaction was completed, the temperature was raised to 70° C., 668 g of a 50% dimethylamine aqueous solution was added, the Mannich reaction was carried out for 1 hour, and then the mixture was cooled.

The resulting polymer solution was diluted with water to pH 1O14,
Concentration: 50, viscosity: 10. A transparent aqueous solution of OOOc p 5 (same below 20°C) is obtained.

This polymer aqueous solution was diluted to a 0.1% aqueous solution and the molecular weight distribution was measured by liquid-mudography.
The average molecular weight was approximately 1.5 million.

It was 2.4 meq/nog, about 80 moles were Mannich-formed, and the remaining methylol groups were 20 moles. This polymer is referred to as paper strength enhancer A.

According to this example, copolymer aqueous solutions with various degrees of polymerization are prepared by changing the amount of initiator, and a Mannich reaction is carried out with dimethylamine of 50 to obtain paper strength enhancers B-F.

2) Performance test In order to investigate the effect of the obtained paper strength enhancer, the Canadian standard freeness value was beaten to 450 ml and 1.NU
KP/LUKP=20/s o (weight ratio) Same as pulp (corrugated cardboard beaten to 450me) □Paper is 3o
wt% was added to make a 1% slurry. To this slurry, 2'wt% of sulfuric acid was added per dry cut plate, and the mixture was stirred at 200 rpm for 1 minute. The pH of this pulp slurry was 5.5. Next, add 0.4% of the polymer shown in Table 1, stir for about 30 seconds, and then
The reactor water properties were checked according to the TAPPI standard method, and a conventional method was used using a hand paper machine for testing.

After press, dry at 120℃ for 3 minutes until the basis weight is 2.
A handmade paper of 2oW/rl was obtained. Then relative humidity 65
Humidity was controlled for 24 hours in the room, and the pressure bursting strength and relative ring crack 171 strength were determined in accordance with JIS.

For comparison, anionic polyacrylamide paper strength enhancer × (molecular weight 2
Similar tests were also conducted on the amphoteric polyacrylamide paper strength enhancer Y (molecular weight: 200,000, 15 mol) and Z.

Note that Z is obtained by adding 0.4 wt % of anionic polyacrylamide (paper strength agent P) and then adding 0.4 wt % of polyamide polyamine epichlorohydrin resin.

The results are shown in Table 1 using the following notation.

◎〉650- ◎) 2.8' O◎〉20005
75-650 ml 0260-280 018.0
-20.0-△ 50'0~574m1 △
2.40-2.59 △ 16.0-17.9
X (500nt X (2,40X 〈
16.0 Table 1 Example 2 1) Production Example 2 Using the same reactor as in Example 1, the procedure was repeated in the same manner as in Example 1, except that the molar ratio of the starting material, the 50% acrylamide aqueous solution, and the N-methylolacrylamide were changed. A copolymerization reaction is carried out, and then a 25% aqueous solution of dimethylamine is added and reacted by adding the same mole of dimethylamine solid content to the number of moles of N-methylolacrylamide, so that the final solid content concentration is 5% aqueous solution. , paper strength enhancer GL is obtained. Their compositions and physical properties are shown in Table 2.

2) Performance test Hand-made paper for testing (weighing 220
g-/m') was obtained, and 1 iL of the product was measured.

The results are shown in Table 3 using the following notation.

◎〉600- ◎＞19.0 ◎＞2.70
0530~600m1! , 017.0~19.0
0250～27゜Δ480～529m1 △15
．． 0~16.9 to 2.30~2.49X (
480-X (15.
A copolymerization reaction was carried out in the same manner as in Example 1 at the molar ratio shown in the table, and then an equimolar amount of dimethylamine was added to the number of moles of N-methylolacrylamide, and the final solid concentration was 5. Obtain force enhancers M to P.

Their compositions and physical properties are shown in Table 4.

This was made into paper in the same manner as in Example 1, and the physical properties were measured.

The results are shown in Table 5 using the same presentation method as in Example 1.

Table 4 Table 5 Patent applicant: Showa Denko Co., Ltd. Agent Sei Kikuchi

Claims (1)

[Claims] After copolymerizing 50 to 9 mol of acrylamide, 3 to 50 mol of N-methylolacrylamide, and 0 to 20 mol of acrylonitrile or methacrylonitrile in an aqueous medium, the amount of methylol groups in the resulting copolymer is reduced. Both are copolymers containing 50 moles of a secondary amine and a Mannich base, and the viscosity of a deionized aqueous solution (pH 9, temperature 20°C) at a concentration of 5 parts by weight is 1. 000~2
An aqueous property improver and dry paper strength enhancer for paper and paperboard containing a water-soluble copolymer having a concentration in the range of 0.0000 centipoise as an active ingredient.