JPH0598595A - Paper strength agent - Google Patents

Abstract

(57) [Summary] [Object] The present invention, by using a specific water-soluble polymer, has an improved adsorptivity to pulp, has an excellent paper strength-improving effect, and further has excellent folding endurance such as paperboard. A useful paper strengthening agent having an improving effect is provided. [Structure] Hydrocarbon group-containing cationic monomer (A) 0.01 having a hydrocarbon group having 4 to 28 carbon atoms and a polymerizable functional group
~ 15 mol%, copolymerizable anionic monomer (B) 0.01 ~
15 mol%, and copolymerizable hydrophilic monomer (C) 70-99.9
A paper strength enhancer comprising a water-soluble copolymer having 8 mol% as a constituent monomer component as an active ingredient. [Effect] By using the paper strength enhancer of the present invention, it is possible to increase the adsorptivity to pulp, obtain an excellent paper strength improving effect, and further increase the folding endurance of paperboard and the like. ..

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel paper strengthening agent. More specifically, the use of a specific water-soluble polymer enhances the adsorptivity to pulp, has an excellent effect of improving paper strength, and further has a useful effect of increasing paper strength such as folding strength of paperboard. Regarding agents.

[0002]

2. Description of the Related Art In recent years, the shortage of forest resources has become a global problem, and there is an increasing tendency to increase the recycling of waste paper.
However, since the fibers of the waste paper pulp are damaged, the paper strength is reduced. Therefore, various paper strengthening agents have been used to prevent the strength of paper products from decreasing. Among them, polyacrylamide-based polymers are widely used to increase the dry paper strength. However, there are problems such as a decrease in the effect of the paper-strengthening agent and an increase in the addition amount of the used paper, which causes stains in the paper-making process due to an increase in the amount added.
On the other hand, the closed system that circulates and uses white water for energy saving and purification of factory wastewater is in progress. As a result, various ions, fine pulp fibers, and various fillers are contained in the white water, which makes it difficult to adsorb the paper strengthening agent to the pulp fibers. In recent years, it has been proposed to introduce a hydrophobic group such as a benzyl group even under these severe conditions so as to improve the fixing property to the hydrophobic portion of the pulp (JP-A-63-92800, etc.). However, there are many points that the paper strength performance is insufficient.

[0003]

The problems to be solved by the present invention are as follows.
In papermaking of paper and paperboard, even with a large proportion of used paper, the paper strength does not decrease, the folding strength of paperboard is excellent, and the adsorptivity does not decrease even in the white water circulation system. To provide a potentiator.

[0004]

Means for Solving the Problems The present invention provides, as a means for solving the above problems, a hydrocarbon group-containing cationic monomer having a hydrocarbon group having a specific carbon number and a polymerizable functional group, Anionic monomer and a paper strength enhancer that uses a water-soluble copolymer obtained by copolymerizing a hydrophilic monomer in an aqueous solution as an active ingredient, enhances adsorptivity to pulp,
We found that we can obtain an excellent effect of improving paper strength,
The present invention has been completed. That is, the present invention is
Hydrocarbon group-containing cationic monomer (A) 0.01 to 15 mol% having a hydrocarbon group having 4 to 28 carbon atoms and a polymerizable functional group, copolymerizable anionic monomer (B) 0.01 to A paper-strengthening agent characterized by comprising a water-soluble copolymer containing 15 mol% and a copolymerizable hydrophilic monomer (C) 70 to 99.98 mol% as a constituent monomer component. It is related.

A hydrocarbon group-containing cationic compound having a hydrocarbon group having 4 to 28 carbon atoms and a polymerizable functional group is a cationic surface active agent described in JP-A-63-196796. It has been proposed for use in a composition, and is used for the purpose of stably emulsifying and dispersing an alkyl ketene dimer and reducing slippage of paper. In the present invention,
Paying attention to the long-chain alkyl group of the above-mentioned hydrocarbon group-containing cationic monomer, copolymerizing it with a copolymerizable hydrophilic monomer, the molecular weight and unit weight of the resulting water-soluble copolymer By optimizing the body composition, even with a large proportion of recycled paper in paper and paperboard making, the paper strength enhancement effect does not decrease, the folding strength of paperboard, etc. is excellent, and even in white water circulation systems. Even so, they have found a paper strengthening agent whose adsorptivity does not decrease.

As described above, the active ingredient of the paper strength enhancer of the present invention is a hydrocarbon group-containing cationic monomer (A) having a hydrocarbon group having 4 to 28 carbon atoms and a polymerizable functional group. A polymerized water-soluble copolymer obtained by copolymerizing a copolymerizable anionic monomer (B) and a copolymerizable hydrophilic monomer (C). The ratio of each monomer component in the copolymer is also important, (A) is 0.01 to 15 mol%, and (B) is
It is necessary that 0.01 to 15 mol% and (C) be 70 to 99.98 mol%. Preferably (A) is 1-10 mol%, (B) is 1-10
Mol%, (C) is 80 to 98 mol%. Cationic monomer
If (A) is less than 0.01 mol%, the effect of the present invention cannot be obtained, and
If it exceeds 15 mol%, a large amount of hydrophobic groups may inhibit hydrogen bonding, resulting in deterioration of paper strength performance. Further, if the anionic monomer (B) is less than 0.01 mol%, the effect as an amphoteric polymer cannot be obtained, and if it exceeds 15 mol%, the balance with the cationic monomer is lost, which is not preferable. ..

The present invention can be used in a wide pH range of water having a pH of 2 to 12 by introducing a cationic monomer (A) and an anionic monomer (B), regardless of whether the paper is acidic or neutral. It is possible, strongly adheres to pulp, and efficiently develops paper strength performance. The cationic monomer (A) having a C4 to C28 hydrocarbon group and a polymerizable functional group according to the present invention is represented by the following general formulas (I), (II) and (III). Examples of the quaternary ammonium salt having a hydrocarbon group having 4 to 28 carbon atoms include acrylic acid, methacrylic acid, acrylamide or methacrylamide, and preferably a methacrylic acid-based cationic compound having good polymerizability.

[0008]

[Chemical 2]

(In the formula, R ₁ represents a hydrogen atom or a methyl group, R ₂ and R ₃ represent a lower alkyl group having 1 to ₃ carbon atoms, and R ₄ represents a hydrocarbon group having 4 to 28 carbon atoms. , Y represents an oxygen atom or -NH-, Z and Z'represent a hydroxyalkylene group having 2 to 4 carbon atoms, and X represents a halogen atom or an acid residue.) The acid residue represented by X Examples thereof include methyl sulfate and ethyl sulfate.

The compounds represented by the general formulas (I), (II) and (III) include 2-hydroxy-3-methacryloyloxypropyl-N, N, N-dimethylalkyl (C ₄ -C ₂₈ ) ammonium salt, 2'-methacryloyloxyethyl-N, N-
Dimethyl-2-hydroxy-3- alkyl (C ₄ ~C ₂₈₎ propylammonium salt, 2'-hydroxy-3'-methacryloyloxy propyl -N, N - dimethyl-3-alkyl (C ₄ ~C ₂₈₎ oxypropyl An ammonium salt etc. can be mentioned.

Examples of the anionic monomer (B) according to the present invention include (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, carboxylic acid group-containing monomers and salts thereof. , Vinyl sulfonic acid, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and other sulfonic acid group-containing monomers and salts thereof, or hydroxyalkyl (meth) acrylate phosphoric acid esters and salts thereof, etc. Can be mentioned.

As the hydrophilic monomer (C) according to the present invention, acrylamide, methacrylamide, N-vinyl-2-
Pyrrolidone, N, N-dimethyl acrylamide, diacetone acrylamide, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, polyethylene glycol monomethacrylate, methoxy polyethylene glycol methacrylate and the like can be mentioned. In the present invention, a cationic monomer capable of copolymerizing a part of the hydrophilic monomer (C) for controlling the amount of cation
It may be replaced with (D), and its amount is 0 to 20 mol%
Is preferred.

As such a cationic monomer, a tertiary amino group such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, or diethylaminopropyl (meth) acrylamide can be used. A vinyl monomer having an inorganic or organic acid salt such as hydrochloric acid, sulfuric acid, nitric acid or acetic acid, or a tertiary amino group-containing vinyl monomer and a quaternizing agent such as methyl chloride, dimethyl sulfuric acid, diethyl sulfuric acid or epichlorohydrin Examples thereof include monomers containing a quaternary ammonium salt obtained by the reaction.

The mechanism of action of the paper strengthening agent of the present invention is not clear yet, but it is presumed as follows. That is, the paper strengthening agent is dominated by interfacial conductive behavior as a polymer electrolyte in the pulp slurry, and its dispersibility and adsorptivity to pulp are affected by pH and various salts. In addition, the molecular weight exerts an aggregating effect on pulp and affects the yield and drainage of fine fibers. The behavior of the polymer after adsorption is
Conformational changes on the pulp surface,
Permeation of the polymer into the pulp pores and transition of the polymer between solids must be considered.

Since the paper strengthening agent of the present invention contains a long-chain hydrophobic and bulky alkyl group, it is considered that it contributes to the improvement of fixing property to the hydrophobic portion of pulp. In addition, since some quaternary nitrogen has a bulky long-chain alkyl group, the paper strengthening agent will become a string even if the electrostatic attraction decreases in a white water circulation system with a high salt concentration. It is difficult and it is considered that the adsorptivity to pulp does not decrease. Further, when the N-alkyl is substituted, the softening point of the paper strengthening agent is lowered and the paper strengthening agent becomes plastic. As a result, it is considered that the adsorbed pulp is also given the characteristic, and the paper strength performance, especially the folding endurance is improved.

The water-soluble copolymer according to the present invention can be obtained by polymerizing a mixture of the monomers (A), (B) and (C) in the presence of a radical initiator. As the solvent, methanol, ethanol, isopropanol, butanol, methyl ethyl ketone, toluene, water and the like and mixed solvents thereof can be used. What is soluble in the solvent used may be selected as the radical polymerization initiator.
For example, 2,2'-azobisisobutyronitrile, 2,2'-azobis- (2,4-dimethylvaleronitrile) 2,2'-azobis (2-amidinopropane) hydrochloride and the like can be used. The polymerization temperature is set by the decomposition temperature of the radical initiator.

The water-soluble copolymer used in the present invention is 15
It is preferable that the aqueous solution having a concentration by weight of 25% has a Brookfield viscosity of 100 to 100,000 centipoise at 25 ° C., and particularly preferably 1,000 to 20,000 centipoise. When it is less than 100 centipoise, the molecular weight is low and the paper strength-enhancing effect is poor. On the other hand, when the viscosity is higher than 100,000 centipoise, the cohesive effect with pulp is strong and the formation of paper is disturbed, resulting in a decrease in paper strength.

The paper strengthening agent of the present invention is used by being added to an aqueous dispersion of pulp. The amount of addition is preferably 0.05 to 5% with respect to the pulp dry weight. The place of addition during the production process may be any place within the papermaking process as long as the pulp is uniformly dispersed in water. Further, it may be used in combination with a filler, a sizing agent, a retention improver, a drainage improver, and other paper strength enhancers.

[0019]

EXAMPLES The present invention will be described in detail below with reference to production examples and examples, but the present invention is not limited to these production examples and examples. The parts in the production examples and examples are based on weight unless otherwise specified. [Synthesis of Water-Soluble Copolymer] Production Example 1 A four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube was charged with 100 parts of a 60% isopropyl alcohol aqueous solution, and the system was replaced with nitrogen. I went. afterwards,
Heated slowly to reflux. There acrylamide 22.4
Part, 2-hydroxy-3-methacryloyloxypropyl dimethylstearyl ammonium chloride 8.3 parts, acrylic acid 1.3 parts and 2,2'-azobisisobutyl nitrile
100 parts of a 60% isopropyl alcohol aqueous solution containing 0.4 parts was added dropwise over 2 hours. After the reaction solution was heated and refluxed for 3 hours after the dropping, 120 parts of water was added to dilute, isopropyl alcohol was distilled off, and the concentration was adjusted to obtain a copolymer aqueous solution having a solid content of 15%. The resulting copolymer aqueous solution had a Brookfield viscosity at 25 ° C of 9,700 centipoise and a pH of
It was 4.7.

Production Examples 2 to 5 and Comparative Production Examples 1 to 4 The total amount of the charged monomers was set to 0.7 mol, the monomer composition was changed as shown in Table 1, and various kinds were prepared in the same manner as in Production Example 1. A polymer was obtained. Production Examples 1-5 and Comparative Production Examples 1-4
Table 1 shows the hydrocarbon group-containing monomer, the anionic monomer, the nonionic monomer, and the measured viscosity.

[0021]

[Table 1]

(Note) (1) Numbers in parentheses represent the mol% charged for each monomer. (2) The viscosity is the Brookfield viscosity of a 15% by weight aqueous solution of each copolymer at 25 ° C, and the viscosity unit CPS is centipoise.

[Comparison of Paper Strengthening Effect] The water-soluble copolymers of Examples 1 to 5 and Comparative Examples 1 to 4 were added, and paper was made into paper to evaluate the paper strength. The procedure is as follows: Canadian Standard Freeness (CSF) pulp beaten to 400 ml (NUK
P) and corrugated waste paper pulp mixture (5/5, 3/7)
Was prepared into a 1.0% concentration slurry, and 1% of the sulfuric acid band was added to the pulp, followed by stirring for 1 minute, and 0.5% of the polymer of Production Example 1 was added to the pulp. Stir for a further 5 minutes. The slurry was made into paper using a TAPPI square sheet machine, pressed, and then dried with a large rotary dryer. JIS paper strength test
The tensile strength, burst strength, tear strength, and folding endurance were measured in accordance with the standard. Similarly, the polymers of Production Examples 2 to 5 and Comparative Production Examples 1 to 4 were added, paper was made into paper, and a paper strength test was conducted. The results are shown in Table 2.

Test conditions Pulp; NUKP (CSF 400 ml) / Corrugated cardboard waste paper (CSF 300 ml)
= 5/5, 3/7 (weight ratio) Basis weight: 70 g / m ² Water: 20 ° C, tap water dryness: 105 ° C x 40 seconds Press: 3.5 kg x 2 minutes Paper force measurement: Room temperature 20 ° C The measurement was performed in a thermostatic chamber with a humidity of 65%. Tensile strength (Tensilon JIS P 8113) Bursting strength (Mullen type burst strength tester JIS P 8112) Folding strength (MIT type folding endurance tester JIS P 8115) Tear strength (Elemendorff tear tester JIS P
8116)

[0025]

[Table 2]

[Comparison of Adsorption Amounts of Polymers] Examples 6 to 10 and Comparative Examples 5 to 8 Assuming actual white water, polymers of Ca ²⁺ , Na ⁺ , and Mg ²⁺ ions in high salt concentration were used. The adsorptivity to pulp was examined. Pulp (NUKP above) with German hardness 0, 20, 50
The mixture was dispersed in hard water of ° dH to a concentration of 0.4%, a sulfuric acid band was added to the pulp at 1%, and then the polymers of Production Examples 1 to 5 and Comparative Production Examples 1 to 3 were added to the pulp at 0.5%. After stirring for 5 minutes, the amount of polymer in the pulp was determined by the amount of nitrogen by the Kjeldahl analysis method after filtering with a glass filter (100 to 150 μm). The results are shown in Table 3.

[0027]

[Table 3]

[0028]

EFFECTS OF THE INVENTION By using the paper strength enhancer of the present invention, it is possible to enhance the adsorptivity to pulp, obtain an excellent paper strength improving effect, and further increase the folding endurance of paperboard and the like. Becomes

Claims (6)

[Claims] 1. A hydrocarbon group-containing cationic monomer (A) having a hydrocarbon group having 4 to 28 carbon atoms and a polymerizable functional group.
0.01 to 15 mol%, copolymerizable anionic monomer (B) 0.
01 to 15 mol% and copolymerizable hydrophilic monomer (C) 70 to
A paper strength enhancer comprising a water-soluble copolymer having 99.98 mol% as a constituent monomer component as an active ingredient. 2. A hydrocarbon group-containing cationic monomer (A) having a hydrocarbon group having 4 to 28 carbon atoms and a polymerizable functional group.
Is a compound selected from the group of compounds represented by the following general formulas (I), (II) and (III): [Chemical 1] (In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ and R ₃
Represents a lower alkyl group having 1 to 3 carbon atoms, R ₄ represents a hydrocarbon group having 4 to 28 carbon atoms, Y represents an oxygen atom or —NH—
Z and Z'represent a hydroxyalkylene group having 2 to 4 carbon atoms, and X represents a halogen atom or an acid residue. ) 3. The anionic monomer (B) is a carboxylic acid group,
The paper strengthening agent according to claim 1, which is a copolymerizable compound having an anionic group selected from a sulfonic acid group and a phosphoric acid ester group or a salt thereof. 4. The hydrophilic monomer (C) is acrylamide, methacrylamide, N-vinyl-2-pyrrolidone, N, N-
Dimethyl acrylamide, diacetone acrylamide,
The paper strengthening according to claim 1, which is one or more copolymerizable compounds selected from the group consisting of 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, polyethylene glycol monomethacrylate, and methoxypolyethylene glycol methacrylate. Agent. 5. The paper-strengthening agent according to claim 1, wherein 20 mol% or less of the hydrophilic monomer (C) is a copolymerizable cationic monomer (D). 6. The paper according to claim 1, wherein the water-soluble copolymer is such that an aqueous solution having a concentration of 15% by weight has a Brookfield viscosity of 100 to 100,000 centipoise at 25 ° C. Strength enhancer.