JP2983713B2 - Paper Strengthening Agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel paper strength agent. More specifically, the use of a specific water-soluble polymer increases the adsorptivity to pulp, has an excellent effect of improving paper strength, and further enhances useful paper strength having an effect of improving folding strength of paperboard and the like. Agent.

[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, the waste paper pulp has a damaged fiber, resulting in a decrease in paper strength. Therefore, in order to prevent the strength of the paper product from decreasing, various paper strength enhancers have been used. Among them, polyacrylamide-based polymers are widely used to increase dry paper strength. However, there are problems such as a decrease in the effect of the paper strength enhancer with an increase in the mixing ratio of the used paper and generation of stains in the papermaking process due to an increase in the amount of the paper strength enhancer.
On the other hand, closed use of circulating and using white water to save energy and purify industrial wastewater is progressing. As a result, the white water contains various ions, pulp fine fibers, and various fillers, which is a severe condition for the adsorption of the paper strength enhancer to the pulp fibers. In recent years, it has been proposed to improve the fixability to the hydrophobic part of pulp by introducing a hydrophobic group such as a benzyl group even under these severe conditions (JP-A-63-92800). However, there are many points where the paper strength performance is insufficient.

[0003]

The problem to be solved by the present invention is as follows.
Even if the mixing ratio of waste paper is high in papermaking of paper and paperboard, the strength of paperboard etc. is not reduced, the folding strength of paperboard etc. is excellent, and the adsorptivity does not decrease even in the white water circulation system It is to provide a paper strength agent.

[0004]

According to the present invention, as a result of various studies for solving the above-mentioned problems, a hydrocarbon group-containing cationic unit having a hydrocarbon group having a specific carbon number and a polymerizable functional group has been obtained. Strength enhancer using a water-soluble copolymer obtained by copolymerizing a monomer and a hydrophilic monomer in an aqueous solution as an active ingredient increases the adsorptivity to pulp, and achieves an excellent paper strength improving effect. It has been found that they can be obtained and the present invention has been accomplished. That is, the present invention provides a hydrocarbon group-containing cationic monomer (A) having a specific hydrocarbon group having 4 to 28 carbon atoms and a polymerizable functional group (A) in an amount of 0.01 to 15 mol%, and a copolymerizable hydrophilic monomer. Monomer (B) 85-99.99 mol% (dashi, hydrophilic
Monomer (B) is a clickable copolymerizable with cationic monomer (A).
Containing the on-monomer (C) at a ratio of 20 mol% or less as an essential component.
) Is a water-soluble copolymer having a monomer component as an active ingredient.

A hydrocarbon group-containing cationic compound having a hydrocarbon group having 4 to 28 carbon atoms and a polymerizable functional group is a cationic surfactant which is disclosed in JP-A-63-196796. It has been proposed to be used in a composition, and has been used for the purpose of stably emulsifying and dispersing an alkyl ketene dimer and reducing paper slippage. In the present invention,
Paying attention to the long-chain alkyl group of the above-mentioned hydrocarbon group-containing cationic monomer, it is copolymerized with a copolymerizable hydrophilic monomer, and the molecular weight and the monomer amount of the obtained water-soluble copolymer are obtained. By optimizing the body composition, even if the ratio of used paper is large in papermaking of paper and paperboard, the folding strength of paperboard etc. is excellent without decreasing the paper strength enhancing effect, and furthermore, the white water circulation system The paper strength enhancer which does not decrease the adsorptivity was also found.

As described above, the active ingredient of the paper strength enhancer of the present invention comprises a hydrocarbon group-containing cationic monomer (A) having a hydrocarbon group having 4 to 28 carbon atoms and a polymerizable functional group. It is a polymerized water-soluble copolymer obtained by copolymerization with a copolymerizable hydrophilic monomer (B) .The ratio of each monomer component in this water-soluble copolymer is also important. And the hydrocarbon group-containing cationic monomer (A) is 0.01 to 15 mol%, preferably 1 to 10 mol%, and the hydrophilic monomer (B) is 85 to 99.99 mol%, preferably 90 to 99 mol%. Mol%. Cationic monomer
If (A) is less than 0.01 mol%, the effects of the present invention cannot be obtained, and
If it exceeds 15 mol%, a large amount of hydrophobic groups inhibit hydrogen bonding,
There is a risk that the paper strength performance will be reduced.

The hydrocarbon group-containing cationic monomer (A) having a hydrocarbon group having 4 to 28 carbon atoms and a polymerizable functional group according to the present invention includes the following general formulas (I) and (II). ) And (I
Cationic monomers selected from the group of compounds represented by II)
Is used , and acrylic acid, methacrylic acid, acrylamide or methacrylamide, preferably a methacrylic acid-based cationic compound having good polymerizability is exemplified.

[0008]

Embedded image

(Wherein, 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 such as methyl sulfate or ethyl sulfate.) (I), examples of the compounds represented by (II) and (III), 2-hydroxy - 3-methacryloyloxy propyl -N, N, N - dimethyl alkyl (C ₄ ~
C ₂₈₎ ammonium salt, 2'-methacryloyloxyethyl -N, N - dimethyl-2-hydroxy-3- alkyl (C ₄
-C ₂₈₎ propylammonium salt, 2'-hydroxy-3'-
Methacryloyloxypropyl-N, N-dimethyl-3-
Alkyl (C ₄ ~C ₂₈₎ propyl ammonium salts and the like.

The hydrophilic monomer (B) according to the present invention includes acrylamide, methacrylamide, N-vinyl-
Examples thereof include 2-pyrrolidone, N, N-dimethylacrylamide, diacetone acrylamide, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, polyethylene glycol monomethacrylate, and methoxypolyethylene glycol methacrylate. In the present invention, a cationic monomer capable of copolymerizing a part of the hydrophilic monomer (B) to control the amount of cation
(C) and Ru replaced. The amount is less than 20 mol%
You . Examples of the cationic monomer include vinyl monomers having a tertiary amino group such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, and diethylaminopropyl (meth) acrylamide. Reaction of an inorganic or organic acid salt such as hydrochloric acid, sulfuric acid or acetic acid, or a tertiary amino group-containing vinyl monomer with a quaternizing agent such as methyl chloride, benzyl chloride, dimethyl sulfate, diethyl sulfate or epichlorohydrin. The resulting quaternary ammonium salt-containing monomer is exemplified.

The mechanism of action of the paper-strength enhancer of the present invention is not yet clear but is presumed as follows. That is, the paper strength enhancer is governed by the interfacial conductivity as a polymer electrolyte in the pulp slurry, and its dispersibility and adsorptivity to pulp are affected by pH and various salts. Further, the molecular weight exerts a flocculating effect on the pulp and affects the yield and drainage of fine fibers. The behavior of the polymer after adsorption is
Conformational change on pulp surface,
The penetration of the polymer into the pores and the transition between the solids of the polymer must be taken into account.

Since the paper strength enhancer of the present invention contains a long-chain hydrophobic and bulky alkyl group, it is considered that it contributes to the improvement of fixability to the hydrophobic portion of pulp. In addition, because some quaternary nitrogens have bulky long-chain alkyl groups, even if the electrostatic attraction decreases in a high salt concentration white water circulation system, the paper strength enhancer becomes thread-like. It is considered that it is difficult to reduce the adsorptivity to pulp. In addition, the N-alkyl substitution lowers the softening point of the paper-strengthening agent, and becomes plastic. As a result, it is considered that the characteristics are imparted to the adsorbed pulp, and the paper strength performance, particularly the folding strength is improved.

The water-soluble copolymer according to the present invention can be obtained by copolymerizing a mixture of the monomers (A) and (B) in the presence of a radical polymerization initiator. As the solvent, methanol, ethanol, isopropanol, butanol, methyl ethyl ketone, toluene, water and the like and a mixed solvent thereof can be used. As the radical polymerization initiator, one that is soluble in the solvent used may be selected.
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 polymerization initiator.

The water-soluble copolymer used in the present invention comprises 15
It is preferable that the aqueous solution having a concentration of weight% has a Brookfield viscosity of 100 to 100,000 centipoise at 25 ° C., particularly preferably 1,000 to 20,000 centipoise. If the viscosity is less than 100 centipoise, the molecular weight is low and the paper strength enhancing effect is inferior. On the other hand, if the viscosity is higher than 100,000 centipoise, the coagulation effect with pulp is strong and the paper formation is disturbed, so that the paper strength is reduced.

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

Hereinafter, the present invention will be described in more detail with reference to Production Examples and Examples, but the present invention is not limited to these Production Examples and Examples. Parts in 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 purged with nitrogen. Was done. afterwards,
Slowly heated to reflux. There acrylamide 27.7
Parts, 3.5 parts of β-methacryloyloxydimethyldimethylstearyl ammonium chloride, 3.5 parts of 3-dimethylaminopropyl methacrylamide diethyl sulfate, and
112 parts of a 60% aqueous isopropyl alcohol solution containing 0.4 part of 2,2'-azobisisobutylnitrile was added dropwise over 2 hours. After the dropwise addition, the reaction solution was heated to reflux for 3 hours, diluted with 100 parts of water, and the isopropyl alcohol was distilled off. The concentration was adjusted to obtain a copolymer aqueous solution having a solid content of 15%. The Brookfield viscosity at 25 ° C. of the resulting aqueous copolymer solution was 9,800 centipoise and the pH was 5.5. Production Examples 2 to 3 and Comparative Production Examples 1 to 4 All the charged monomers were charged at 0.7 mol, and the monomer compositions were changed as shown in Table 1. Various polymers were produced in the same manner as in Production Example 1. Obtained. Production Examples 1 to 3 and Comparative Production Examples 1 to 3
A hydrocarbon group-containing monomer, a nonionic monomer, a cationic monomer, an aromatic-containing monomer in Comparative Production Example 4, a nonionic monomer, an anionic monomer, and Table 1 shows the measured viscosities.

Production Examples 2 to 5 and Comparative Production Examples 1 to 4 The total monomer amount was 0.7 mol, and the monomer composition was changed as shown in Table 1. A polymer was obtained. Production Examples 1 to 5 and Comparative Production Examples 1 to 3
A hydrocarbon group-containing monomer, a nonionic monomer, a cationic monomer, an aromatic-containing monomer in Comparative Production Example 4, a nonionic monomer, an anionic monomer, and Table 1 shows the measured viscosities.

[0018]

[Table 1]

(Note) (1) The number in parentheses indicates the charged mole% of each monomer. (2) The viscosity indicates a Brookfield viscosity of a 15% by weight aqueous solution of each copolymer at 25 ° C., and the unit of viscosity CPS is centipoise. [Comparison of Paper Strength Enhancing Effect] Examples 1 to 3 and Comparative Examples 1 to 4 The water-soluble copolymers of Production Example 1 were added to paper, and a paper strength test was conducted. The procedure is as follows: Canadian Standard Freeness (CSF) beaten to 400ml pulp (NUKP)
And a mixture of cardboard waste paper pulp (mixed weight ratio of NUKP and waste paper pulp 5/5, 3/7) was prepared into a 1.0% concentration slurry,
After stirring for 1 minute, the polymer of Production Example 1 was added to pulp.
0.5% was added. Stir for another 5 minutes. This slurry
Paper was made with a TAPPI square sheet machine, pressed and then dried with a large rotary dryer. In the paper strength test, tensile strength, burst strength, tear strength and bending strength were measured in accordance with JIS standards. Similarly, the polymers of Production Examples 2 to 3 and Comparative Production Examples 1 to 4 were added, and a paper was made and a paper strength test was performed. The test conditions are as follows. Table 2 shows the paper strength test results.

[0020] Test Conditions pulp; NUKP (CSF400ml) / cardboard waste paper (CSF300ml) = 5/5, 3/7 ( by weight) basis weight; 70g / m ² water; 20 ° C., tap water drying; 105 ° C. × 40 seconds Press: 3.5 kg × 2 minutes Paper strength measurement: Measurement was performed in a constant temperature room at room temperature of 20 ° C. and humidity of 65%. Tensile strength (tensilon type tensile tester, JIS P 8113) Burst strength (Mullen type burst strength tester, JIS P 8112) Folding strength (MIT type bending strength tester, JIS P 8115) Mold tearing tester, JIS P 8116)

[0021]

[Table 2]

[Comparison of Polymer Adsorption Amounts] Examples 4 to 6 and Comparative Examples 5 to 8 Assuming actual white water, the polymer in a high salt concentration containing Ca ²⁺ , Na ⁺ , and Mg ²⁺ ions was used. The adsorptivity to pulp was studied. Pulp (NUKP above) with German hardness, 0, 20, 50
Dispersed in hard water of degree dH to make the concentration 0.4%, Production Example 1
0.5% of pulp with polymers of Comparative Examples 1-3 and Comparative Production Examples 1-4
Was added. After stirring for 5 minutes, glass filter (100 ~
After filtration through a filter (150 μm), the amount of polymer in the pulp was determined by the amount of nitrogen by Kjeldahl analysis. Table 3 shows the results.

[0023]

[Table 3]

(Note) The numbers other than the hardness in the table indicate the adsorption rate (%) of the polymer to the pulp.

[0025]

By using the paper strength enhancer of the present invention, the adsorptivity to pulp can be increased, an excellent paper strength improvement effect can be obtained, and the folding strength of paperboard can be further increased. Becomes

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) D21H 17/45

Claims (3)

(57) [Claims] 1. A compound represented by the following general formulas (I), (II) and (III):
Cationic monomer (A) selected from the group consisting of
~ 15 mol%, and copolymerizable hydrophilic monomer (B) 85 ~ 9
9.99 mol% (but the hydrophilic monomer (B) is a cation
20 monomers of the cationic monomer (C) copolymerizable with the monomer (A)
Paper strength agent characterized by containing, as an active ingredient, a water-soluble copolymer of comprising as essential) Le% following ratios between constituent monomer component. Embedded image (Wherein, 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 is carbon
Y represents an oxygen atom or -N
H and Z and Z ′ each represent a hydroxyl group having 2 to 4 carbon atoms.
X represents a halogen atom or an acid residue.
I forgot. ) 2. The method according to claim 1, wherein the hydrophilic monomer (B) is acrylamide, methacrylamide, N-vinyl-2-pyrrolidone, N, N-
Dimethyl acrylamide, diacetone acrylamide,
The paper strength according to claim 1 , comprising one or more nonionic monomers selected from the group consisting of 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, polyethylene glycol monomethacrylate, and methoxypolyethylene glycol methacrylate. Enhancer. 3. A water-soluble copolymer is, paper strength agent according to claim 1 or 2, wherein an aqueous solution of 15 wt% concentration and has a Brookfield viscosity of 100 to 100,000 centipoise At a 25 ° C..