JPS5930995A - Filterability enhancer and dry strength enhancer of paper and paperboard - 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 relates to an internally added paper strength enhancer that is made of a water-soluble multi-component copolymer containing acrylamide or methacrylamide as a main component and has the effect of improving water resistance during the production of paper and paperboard.

The supply situation for raw wood, the raw material for paper, is only getting worse.
Increasing the proportion of used paper converted into hardwood and lumber, and increasing the yield of valves are important issues.

Therefore, the number of fine fiber cords in the papermaking raw material inevitably increases, and the papermaking conditions deteriorate accordingly.

In addition, as part of environmental measures, it has become impossible to avoid closed pulp, paper, and paperboard manufacturing processes, and as a result, papermaking conditions such as rising water temperatures and deteriorating water quality have deteriorated rapidly. This has a major impact on the performance of chemicals.

Conventionally, anionic polyacrylamide resins have been widely used as paper strength enhancers in paper manufacturing processes.

However, such anionic polyacrylamide resin requires sulfuric acid band as a fixing agent, so it is limited to use in an acidic region, resulting in problems with drainage, corrosion during paper making, and low fixation rate, making it difficult to maintain sufficient paper strength. There are problems such as not being able to
Particularly in the recent deterioration of paper-making conditions, sufficient functionality cannot be expressed.

Cationic paper strength enhancers that often require fixing agents such as sulfuric acid have also been developed;
Although the various polyamide polyamine resins shown in the above contribute to improving paper strength, they tend to foam during paper making, and because the molecular weight cannot be increased, they have disadvantages such as poor furnace water resistance effects.

On the other hand, cationic paper strength enhancers such as copolymers of acrylamide and dimethylamine ethyl methacrylate have been developed, and although they are effective over a wide pI-T range, the paper strength obtained is still insufficient. It's hard to say that there is.

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

Because ash cardboard is used to protect and store contents, and because it is stacked during transportation, it is required to have higher compressive strength, such as ring-crane strength, than general 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 filter paper with sufficiently excellent compressive strength 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, and although this can achieve a moderately high compressive strength, it also increases the content of waste paper. The current situation is that the effects of chemicals are becoming insufficient under recent papermaking conditions that have deteriorated due to the progress of closed drainage.

On the other hand, in papermaking processes such as paperboard, reactor water properties improvers are used for fast reactor water as machines run at higher speeds. A very strong cationic polymer or a cationic polymer with a very high molecular weight (more than 3 million) is used, especially a Mannich compound of polyacrylamide, and acrylamide-dimethylamine ethyl methacrylate copolymer is used. .

These reactor water quality improvers have extremely high molecular weights. Therefore, if the amount used is too large, the grip formation will be poor.

In addition, anionic polyacrylamide resins used to strengthen the paper strength of paperboard generally have a low molecular weight of 200,000 to 300,000, so even if they are used in combination with sulfuric acid as a fixing agent, they do not exhibit much of the effect of reactor water. In the paperboard making process, a furnace water property improver is used in combination with anionic polyacrylamide resin.

The present inventors have achieved the functions of a conventional paper strength enhancer and water resistance improver with a single agent in the paper and paperboard manufacturing process, and have also achieved an advantage not found in known paper strength enhancers.

With the aim of obtaining a paper strength enhancer that can impart a high compressive strength, we have conducted extensive research and found that 50-96 mol% of acrylamide or methacrylamide, 3-30 mol% of N-methylolacrylamide or N-methylolmethacrylamide [In the formula, R1 is a hydrogen atom or a methyl group, R2 and R3 are each an alkyl group having 1 to 4 carbon atoms, and A
represents an alkylene group having 1 to 3 carbon atoms]; at least one 1 to 20 molar group selected from aminoalkyl esters thereof, acid addition salts thereof, and quaternary salts thereof; and methyl of acrylic acid or methacrylic acid; At least 1 type of hydroxyethyl or hydroxypropyl ester, acrylonitrile, methacrylonitrile, or vinegar
A copolymer in which ~20 moles of methylol groups in the resulting copolymer are copolymerized in an aqueous medium, and 50 moles of the methylol groups in the resulting copolymer are converted into Mannich bases using secondary amines. , the viscosity of a deionized aqueous solution (pH 9, temperature 20°C) with a concentration of more than 5% by weight is 1. It has been discovered that a water-soluble copolymer having a centipoise range of ooo to 200 to 000 centipoise achieves all of the above objects, and the present invention has now been completed.

The present invention will be explained in more detail below.

The copolymers of the present invention exhibit one molecule or a methyl group. ) 50-97 moles qb of acrylamide or methacrylamide: 1 3 to 20 moles of N-methylolacrylamide or N-methylolmethacrylamide expressed as (the same); (wherein R1 is the same as above, R2 and R3 are an alkyl group having 1 to 4 carbon atoms, and A is an alkyl group having 1 to 4 carbon atoms.
1 to 20 molar ratio of at least one aminoalkyl ester selected from acid addition salts thereof and quaternary salts thereof (representing an alkylene group of Same, ■ R1 Z, u-Co2CH3, -Co2C2H40H, -CO
2CI-I, CH(OH)CH3, -CN, -0COC
H3 (where R1 is a hydrogen atom). ] At least 50 monomers of methylol groups in a copolymer containing 0 to 20 monomers of at least one kind of hydrophobic monomer copolymerizable with the above (g), It is a water-soluble resin with a high molecular weight, which is made into a Mannich base using a secondary amine, and has 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 suspension 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 of these and reducing agents, azobisamidinopropane hydrochloride, azobis Adding an azo compound such as isobutyronitrile and further an initiator such as a combination of various reducing agents such as sodium sulfite and an azo compound to the monomer mixture in an amount of 0.01 to 2% by weight;
An aqueous solution having a monomer concentration of 5-50% may be heated to 20-100°C under a nitrogen atmosphere and polymerized for 1-10 hours.

Further, in this case, a conditioner such as an acid or a base, or a chain transfer agent such as infropanol 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 second used in this reaction
As the primary amine, lower alkylamines, particularly dimethylamine, are preferred, but cyclic amines such as cyclohexylamine, lower alkanolamines such as jetanolamine, etc. 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 molar units or more, preferably 80 molar units or more of the methylol groups in the copolymer be converted into Mannich bases. However, when the degree of cationization of the copolymer resin is too high, the cohesive force is too strong, resulting in poor formation, poor paper strength, and poor paper formability. In the copolymer, the amount of the constituent monomer 〇 containing a methylol group does not exceed 50 moles, so even if all of it is converted to a Mannich base, there will be no problem. Therefore, it is preferable to use the secondary amine used in the reaction in an amount slightly in excess of the theoretical amount within the range of about 90.5 to 1.4 mol per mol of the N-methylol (ivy) acrylamide component. Although there is no particular restriction on the reaction temperature for 1 hour, the reaction is usually carried out at 20 to 70°C for about 0.5 to 10 hours. Similarly, polyacrylamide Mannich compound, which is commonly used as an amphoteric paper strength enhancer, has a molecular weight of about 100,000 to 200,000, and after polymerizing acrylamide to make polyacrylamide, formalin and dimethyl Obtained by performing a Mannich reaction using an amine. However, even if the polymer prepared by this method has a high molecular weight with the same viscosity as the copolymer of the present invention in a 5% aqueous solution, the polymer of the present invention has improved reactor water resistance, improved ring crush strength, and increased paper strength. Almost no effect is observed, the cohesiveness is strong, and the formation of formation is poor. Although the reason for this is not well understood, it is presumed that the distribution of cationic groups in the polymer chain is different.

In addition, the polymer obtained by subjecting the above polyacrylamide to the Mannich reaction using formalin and dimethylamine has a molecular weight of about 1 million, even if it is not neutralized or neutralized to pH 6 or less after the reaction is completed. 5 as viscosity
When the aqueous solution reaches around 8,000 cps, gelation may occur during the reaction or may occur during storage.
Unusable.

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, and has very good storage stability at 30°C and remains stable for about 1 month or more, making it a significant difference in practical use. It was recognized that there is. 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. Viscometer) is i, OOO ~ 200
,000 cps. Viscosity is 1. ．． If it is less than 200,000 cps, a sufficient effect will not be exhibited, while if it exceeds 200,000 cps, the cohesive force will be too strong, resulting in poor formation, poor paper strength, and poor paper formability. be. Preferably 2,0
A range of 00 to 100,000 CI)S is preferred.

The cationic polymer of the present invention can be used in the paper/board making process, with or without sulfuric acid band, in accordance with conventionally known methods, for example, 1% per pulp.
By adding 02-i, 5wt ratio 1 or 01-Q, 7wt ratio, the reactor water resistance can be greatly increased, and at the same time, paper strength such as 1c ring crush strength and bursting strength can be improved.

The paper strength enhancer of the present invention is characterized in that it can improve p-aqueous properties in the papermaking process and at the same time impart excellent compressive strength (ring crush 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.

Example 1 ■) Production Example 50 140 g of thiacrylamide, 20 g of N-methylolacrylamide, 10 I of β-methacryloyloxyeltrimethylammonium chloride, and 10.9 g of acrylonitrile were placed in a flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet. and add deionized water to bring the total volume to 1.
The weight shall be 960g. The temperature of the solution was maintained at 40°C, aerated with nitrogen gas for about 1 hour, and 20.9% sodium sulfite 2q6 aqueous solution was mixed with 20.9% sodium sulfite 2q6 aqueous solution.
0 g, 1 aqueous solution of azobisamidinopropane hydrochloride
Add 0I to start polymerization. The temperature of the solution increases due to the heat of polymerization. After the reaction was completed, the temperature was raised to 70° C., 66.8 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 aqueous solution was diluted with water to give a pH of 9.0, a concentration of 5.0, and a viscosity of 4000.
A transparent aqueous solution of cpS (same below 20°C) is obtained. Colloid equivalent analysis and methylol group titration analysis revealed that 90 of the methylol groups in this copolymer were converted to Mannich, and 10% of the V% remained as methylol groups. This polymer aqueous solution was diluted to an O01 aqueous solution, and the molecular weight distribution was measured by liquid chromatography, and the average molecular weight was about 1 million. This polymer is referred to as paper strength enhancer A.

According to this example, copolymer aqueous solutions with various degrees of polymerization were prepared by changing the amount of initiator, and a Mannich reaction was 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, NUKP/
LUKP=20/80 C weight ratio)
50m7! Added 30W of beaten cardboard waste paper to 1
It was made into slurry.

After adding 92 parts by weight of sulfuric acid per dry pulp to this slurry, 04 parts of the polymer shown in Table 1 was added,
After stirring for about 30 seconds, check the reactor water properties according to JIS, and
Paper was made in a conventional manner using a Sensho machine for APPI standard method testing, and after pressing, it was dried at 120°C for 3 minutes to give a basis weight of 220 ji.
/n? I obtained handmade paper.

Thereafter, the relative humidity was controlled at 65 degrees for 24 hours, and the specific burst strength and specific ring crush strength were measured according to JIS.

For the same comparison, a representative anionic paper strength enhancer X (molecular weight 200,000, hydrolysis degree 10
Similar tests were also conducted on the amphoteric polyacrylamide paper strength enhancer Y (molecular weight 200,015 molar Mannich compound).

Z is anionic polyacrylamide paper strength enhancer
．． After adding 4 parts, 1 wt% of polyamide polyamine epichlorohydrin resin was added.

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

◎) 650m ◎) 2.80 ◎〉2000
575-650m1 ○2.60-2.80 018
0~200△500~574ml 2.4-0-2
．． 79 △160~179X <500tne,
X (2,40 A copolymerization reaction was carried out in the same manner as in Example 1, and then a 50% aqueous solution of dimethylamine was added in equal moles of solid dimethylamine to the number of moles of N-methylolacrylamide, and the reaction was carried out at 50°C for 5 hours. Then, make sure that the final solid content concentration is 5% aqueous solution.

Paper strength enhancer GL is obtained. The composition and physical properties of these
Shown in the table.

2) Performance test Hand-made paper for testing (basis weight 180
g/m) was obtained and its physical properties were measured.

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

◎〉600- ◎)＞19.0 ◎)2.7
00530~600-017.0~19.0 02.5
0-2.70△480-530- △15.0-169
△2.30-2.49X (480d
(15, OX 2.30 Table 3 test results Evaluation G △ △ △FailH◎ ○○Appropriate■ ○ ○ ○ 〃 J ○ ○ ○ 〃K ◎ ◎ ◎ 〃 L △ △ △Fail Comparative example X × × × Fail 〃Y△ ×
×No〃Z△△×No Example 3 Using the same reactor as in Example 1, acrylamide, N-methylolacrylamide, β-methacryloyloxyethyltrimethylammonium chloride, and acrylonitrile were mixed at the molar ratios shown in Table 5. A copolymerization reaction was carried out in the same manner as in Example 1, and then dimethylamine was added to N-
Equivalent moles to the number of moles of methylol acrylamide are added and reacted in the same manner as in Example 1 to obtain various paper strength enhancers M to P having a final solid concentration of 5% aqueous solution. 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 5 Patent applicant: Showa Denko Co., Ltd. Agent Sei Kikuchi

Claims (1)

[Claims] Acrylamide or methacrylamide 50-96 mol % N-methylolmethacrylamide or N-methylolmethacrylamide 3-30 mole [wherein R7 is a hydrogen atom or a methyl group, R2 and R3 are each between - or different alkyl groups having 1 to 4 carbon atoms, and A represents an alkylene group having 1 to 3 carbon atoms], acid addition salts thereof, and quaternary salts thereof. After copolymerizing in an aqueous medium 0 to 20 moles of at least one of methyl, hydroquinethyl or hydroxypropyl ester of acrylic acid or methacrylic acid, acrylonitrile, methacrylonitrile or vinegar, the obtained A deionized aqueous solution (p
H9, temperature 20℃) viscosity is i, o o o ~ 200,
An agent for improving furnace water properties and dry paper strength for paper and paperboard, which contains a water-soluble copolymer having a water-soluble copolymer of 0.000 centipoise as an active ingredient.