JP7151201B2 - Pitch control agent and pitch control method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pitch control agent and a pitch control method. More particularly, the present invention relates to a pitch control agent and a pitch control method capable of effectively suppressing or preventing pitch adhesion in the pulp or paper manufacturing process.

Pitch in the pulp and paper manufacturing process includes natural resins and gum substances released from wood, pulp or paper, and organic substances derived from additives used in the pulp or paper manufacturing process. is a water-insoluble sticky substance composed mainly of In general, pitch is dispersed in colloidal form during the pulp or paper manufacturing process, especially in white water. It is thought that the colloidal state is destroyed, aggregates, and becomes huge due to such factors. Agglomerated and enlarged pitch adheres to pulp and paper due to its stickiness, and also adheres to manufacturing equipment such as fan pumps, pipes, chests, wires, felts, and rolls. Further, the pitch is later exfoliated and reattached to the pulp or paper, causing pitch problems such as deterioration of quality due to the occurrence of stains and defects on the paper, and deterioration of productivity and workability due to the occurrence of paper breakage.

It is known to use surfactants, polymers, talc, etc. as pitch control agents as a countermeasure against pitch disturbance. For example, Patent Document 1 describes using a surfactant as a pitch control agent, and Patent Document 2 describes using a cationic polymer as a pitch control agent.

JP 2015-14068 A Japanese Unexamined Patent Application Publication No. 2004-44067

In recent years, due to the diversification of paper, the amount of chemicals used has increased, the content of waste paper has increased, the quality of waste paper has deteriorated, and the water used in the process has become closed. ing. Pitch control agents are also required to be able to more effectively suppress pitch disturbances. However, the fact is that a pitch control agent that can fully meet such demands has not yet been obtained. For example, surfactants such as those described in Patent Document 1 have the problem of degrading workability due to the generation of foam and causing problems in the drainage process. In addition, the cationic polymer as described in Patent Document 2 reacts with anionic components (sizing agents, paper strength agents, antifoaming agents, etc.) and dyes, and there is a problem that the effect of suppressing pitch cannot be sufficiently exhibited. there were. It should be noted that talc does not have a sufficiently high ability to detackify pitch, and in order to suppress pitch disturbance more effectively, it is necessary to increase the amount used, resulting in problems such as wear of equipment. There is fear.

In view of the above problems, an object of the present invention is to provide a pitch control agent capable of suppressing the generation of bubbles and exhibiting a high pitch control effect, and a pitch control method.

The present inventors have made intensive studies to solve the above problems, and as a result, found that the above problems can be solved by using a pitch control agent that is an aqueous suspension of hectorite, and completed the present invention. did.

That is, the present invention provides the following [1] to [11].
[1] A pitch control agent that is an aqueous hectorite suspension containing hectorite, a dispersant, and water.
[2] The pitch control agent according to [1], wherein the dispersant is an acrylate polymer having a weight average molecular weight of 1,000 to 10,000, and the hectorite content is 1 to 20% by mass.
[3] The acrylate-based polymer is a homopolymer of acrylate, a copolymer of acrylate and 2-hydroxy-3-allyloxypropanesulfonic acid or a salt thereof, or acrylate and 2 - The pitch control agent according to [2], which is a copolymer of hydroxy-3-allyloxypropanesulfonic acid and a salt thereof.
[4] The pitch control agent according to [2] or [3], wherein the content of the acrylate polymer is 0.01 to 5% by mass.
[5] The pitch control agent according to any one of [1] to [4], which has a pH of 7 to 11.
[6] The pitch control agent according to any one of [1] to [5], which has a viscosity of 400 to 3000 mPa·s at 20°C.
[7] The pitch control agent according to any one of [1] to [6], further comprising a pH adjuster.
[8] The pitch control agent according to any one of [1] to [7] is added to at least part of a paper manufacturing facility, at least a part of a pulp manufacturing facility, paper in a paper manufacturing facility, and/or A pitch control method comprising spraying at least one target of pulp and pulp in a pulp manufacturing facility.
[9] The pitch control method according to [8], wherein washing water containing the pitch control agent is sprayed toward the object.
[10] The pitch control method according to [9], wherein the washing water contains the pitch control agent such that the solid content per liter of the washing water is 0.01 to 1000 mg.
[11] A pitch control method comprising adding the pitch control agent according to any one of [1] to [7] to pulp in the pulp or paper manufacturing process.
[12] The pitch control agent according to [11], wherein the pitch control agent is added to the pulp so that the mass of the solid content other than the pulp is 0.01 to 1250 g per 1 t of mass of the pulp. pitch control method.

ADVANTAGE OF THE INVENTION According to this invention, generation|occurrence|production of a bubble can be suppressed and the pitch control agent which can exhibit a high pitch control effect, and a pitch control method can be provided.

Embodiments of the present invention will be described below. In addition, in this specification, the lower limit value and the upper limit value described stepwise for preferable numerical ranges (for example, ranges of content etc.) can be independently combined.

<Pitch control agent>
The pitch control agent according to embodiments of the present invention is an aqueous hectorite suspension comprising hectorite, a dispersant and water.

Hectorite is a type of trihedral scumetite, in which three divalent cations such as Ca and Mg are incorporated into the octahedron. Incidentally, bentonite (clay whose main component is montmorillonite) is a type of dioctahedral scometite, and two trivalent cations such as Al are incorporated in the octahedron. That is, hectorite has a different structure from bentonite.
If a phosphoric acid-based dispersant or a carboxylic acid-based dispersant in the form of a free acid is used, low-solubility aluminum phosphate, calcium phosphate, magnesium phosphate, etc. may precipitate or hydrogel, which may affect the stability of the aqueous suspension. may harm On the other hand, an aqueous suspension of hectorite hardly produces precipitates, does not gel, and is excellent in storage stability.

Hectorite used in the pitch control agent of the present embodiment is a type of trioctahedral scumetite. Hectorite may be naturally occurring or artificially synthesized. Synthetic hectorites include Laponite EP, RD, RDS, SL25 and S482 from BYK; Lucentite SWN and SWF from Corp Chemical; Bentone SD-3, HC, EW, MA and from Elementis Specialties. LT etc. can be mentioned.

The volume average particle size of hectorite is preferably 0.01 to 2 μm, more preferably 0.01 to 1 μm. If the volume average particle size is 2 μm or less, it becomes easy to maintain a good suspension state. If the volume average particle size is 0.01 μm or more, it becomes easier to avoid precipitation or gelation of hectorite due to aggregation. The volume average particle size can be measured with a laser diffraction scattering particle size analyzer.

The amount of hectorite contained in the pitch control agent of the present embodiment is preferably 1 to 20% by mass, more preferably 3 to 20% by mass, more preferably 3 to 20% by mass, based on the mass of the aqueous suspension that is the pitch control agent. is 3 to 15% by mass.

A preferred dispersant for use in this embodiment is an acrylate-based polymer. The acrylate-based polymer is preferably a homopolymer (homopolymer) of acrylate or a copolymer (copolymer) of acrylate and one or more other monomers. Acrylate includes sodium acrylate, potassium acrylate, ammonium acrylate and the like. In the acrylate-based polymer, the amount of structural units derived from acrylate is preferably 70 to 100 mol % of the total structural units.

Other monomers include acrylic acid, methacrylic acid and its salts, itaconic acid and its salts, maleic acid, sodium maleate, ammonium maleate; acrylic esters such as methyl acrylate and ethyl acrylate; methyl methacrylate , methacrylic acid esters such as ethyl methacrylate; aromatic vinyls such as styrene, α-methylstyrene, p-methylstyrene; acrylonitrile, methacrylonitrile; acrylamide, methacrylamide, N-methylolacrylamide; N-propylmaleimide, N- Cyclohexylmaleimide, No-chlorophenylmaleimide; 2-hydroxy-3-allyloxypropanesulfonic acid and its salts, 2-acrylamido-2-methylpropanesulfonic acid and its salts; isobutylene, vinyl acetate and the like. Only one type of other monomer may be used, or two or more types may be used. Among these other monomers, 2-hydroxy-3-allyloxypropanesulfonic acid and/or salts thereof are preferred, and 2-hydroxy-3-allyloxypropanesulfonic acid and salts thereof are more preferred.

The weight average molecular weight of the acrylate-based polymer is preferably 1,000 to 10,000, more preferably 1,200 to 9,000, still more preferably 1,500 to 8,000, and still more preferably 1,700 to 7,000. An acrylate-based polymer having a weight-average molecular weight within this range helps uniform dispersion of hectorite in water and suppresses an increase in the viscosity of the aqueous suspension during storage. The weight average molecular weight is a value converted to standard polyacrylic acid by gel permeation chromatography (GPC method).

The amount of the dispersant contained in the pitch control agent is preferably 0.01 to 5% by mass, more preferably 0.09 to 3% by mass, based on the mass of the aqueous suspension that is the pitch control agent, It is preferably 0.1 to 25% by mass, more preferably 0.3 to 20% by mass, relative to the mass of hectorite.

The water used in the pitch control agent of the present embodiment is not particularly limited by its hardness, but from the viewpoint of suppressing precipitates, the hardness is preferably 0 to 120 mg/L, more preferably 0 to 60 mg/L, and more preferably 0 to 60 mg/L. Preferably 0-10 mg/L, most preferably 0 mg/L. Pure water such as RO water, deionized water, distilled water is most preferably used. The amount of water contained in the aqueous suspension of the present embodiment is preferably 75-99% by mass, more preferably 82-97% by mass.

The aqueous suspension used as the pitch control agent of the present embodiment is not particularly limited by its preparation method. For example, an aqueous suspension can be prepared by the following procedure. First, a solution is obtained by adding a predetermined amount of an acrylate-based polymer to room-temperature pure water in a container and stirring the mixture. A predetermined amount of hectorite is added little by little while the solution is vigorously stirred. An aqueous suspension can be obtained by stirring the hectorite-added solution until uniform.

The aqueous suspension, which is the pitch control agent of the present embodiment, preferably has a viscosity of 400 to 3000 mPa·s, more preferably 700 to 2000 mPa·s. In the specification of the present application, the viscosity of an aqueous suspension is a value measured at 20° C. using a Brookfield C-type rotational viscometer (No.3 rotor, 30 rpm) according to the procedure of JIS K7117-1. .
The pH of the aqueous suspension, which is the pitch control agent of the present embodiment, is preferably 7-11, more preferably 9-11. By setting the pH to 7 or more, the salt form in the acrylate-based polymer decreases and the free acid form increases, and the positively charged edge portion of hectorite forms an edge-to-face bond (card house structure). By doing so, it is possible to suppress the tendency of gelation to proceed. By adjusting the pH to 11 or less, it is possible to prevent the alkalinity from becoming too strong and to easily obtain the desired effect of suppressing pitch adhesion.

The pitch control agent of the present embodiment may further contain components different from hectorite and the dispersant described above. For example, it may contain a pH adjuster.

<Pitch control method>
In a first aspect of the pitch control method of the present invention, (a) at least part of the manufacturing equipment in the paper or pulp manufacturing process, (b) the paper and / or pulp in the paper manufacturing equipment, and (c ) Sprinkling the above-mentioned pitch control agent toward at least one object of pulp in a pulp manufacturing facility.
Examples of specific parts of the manufacturing apparatus to which the pitch control agent is sprayed and to which pitch is likely to adhere include wires, felts, rolls, and the like. By spraying pitch control agents on the parts of paper and pulp manufacturing equipment where pitch can adhere, and by spraying pitch control agents on paper and pulp, it is possible to prevent the adhesion of pitch to paper manufacturing equipment and pulp manufacturing equipment. To prevent. In addition, it is possible to prevent the pitch from adhering to the paper during or after paper manufacturing.

In the first aspect, the pitch control agent is preferably added to washing water and sprayed. Also, the pitch control agent is preferably sprayed as an aqueous solution. The method of spraying the pitch control agent is not particularly limited, but it is preferable to spray or spray in the form of a shower by pressurizing 10 to 1000 ppm into the washing shower line.
The amount of the pitch control agent added to the washing water is preferably 1 to 10000 mg, more preferably 2 to 5000 mg, still more preferably 5 to 3000 mg per liter of washing water.
When the amount of the pitch control agent to be added per 1 L of washing water is 1 mg or more, it becomes easier to prevent the effect of preventing adhesion of pitch from becoming insufficient. A sufficient effect can be obtained when the amount of the pitch control agent added per liter of washing water is 10,000 mg or less, and it is usually not necessary to add the pitch control agent exceeding this amount.
When adding the pitch control agent to the washing water, the content of the solid content (smectite and dispersant) per liter of washing water is preferably 0.01 to 1000 mg, more preferably 0.02 to 500 mg, and even more preferably A pitch control agent is added so as to be 0.05 to 300 mg. In addition, the content of hectorite contained in the washing water is preferably 0.01 to 700 mg, more preferably 0.1 to 100 mg, still more preferably 0.2 to 90 mg, and even more preferably 1 L of washing water. A pitch control agent is added to the washing water so that the weight is 0.5 to 80 mg. The content of the dispersant in the washing water to which the pitch control agent has been added is preferably 0.01 to 10% by mass, more preferably 0.02 to 8% by mass, and still more preferably 0% by mass, relative to the mass of hectorite. .05 to 7% by mass.
If the content of solids per liter of washing water is 0.01 mg or more, it becomes easier to prevent the effect of preventing adhesion of pitch from becoming insufficient. A sufficient effect can be obtained if the solids content per 1 L of washing water is 1000 mg or less, and it is usually not necessary to add the pitch control agent in an amount that would cause the content to exceed this.

In a second aspect of the pitch control method of the present invention, the above-described pitch control agent is added to pulp in the pulp or paper manufacturing process. The addition to the pulp prevents the pitch from sticking to the pulp and paper manufacturing equipment.
In the second aspect, the amount of the pitch control agent added to the pulp is preferably 1 to 5000 g, more preferably 2 to 3000 g, and even more preferably 5 to 2000 g per 1 t of pulp mass.
When the amount of the pitch control agent to be added is 1 g or more per 1 ton of pulp, it becomes easier to prevent the effect of preventing adhesion of pitch to pulp from becoming insufficient. A sufficient effect can be obtained when the amount of the pitch control agent added is 5000 g or less per 1 t of pulp, and it is usually not necessary to add more than 5000 g of the pitch control agent per 1 t of pulp.
In the second aspect, when adding the pitch control agent to the pulp, the mass of the solid content (smectite and dispersant) other than the pulp per 1 t of pulp mass is preferably 0.01 to 1250 g, and more The pitch control agent is preferably added in an amount of 0.02 to 1000 g, more preferably 0.05 to 500 g, particularly preferably 0.1 to 250 g.
If the amount of addition is such that the mass of the solid content per 1 ton of pulp is 0.01 g or more, it becomes easier to prevent the effect of preventing adhesion of pitch from becoming insufficient. The amount of the pitch control agent to be added is such that the mass of the solid content per 1 ton of pulp is 5000 g or less, and a sufficient effect can be obtained.

In the first and second aspects of the pitch control method, the pitch control agent and other ingredients may be used in combination. Components that can be used in combination with the pitch control agent include, for example, organic acids, inorganic acids, and nonionic polymers. In addition, surfactants such as nonionic surfactants, cationic surfactants, and anionic surfactants can be used in combination as other components as long as the content does not generate foam or the amount of foam generation is reduced to the extent that it does not interfere with practical use. You can also

The mechanism by which the pitch control agent according to the embodiment of the present invention effectively suppresses pitch adhesion is not limited to this, but one reason is that the hectorite contained in the pitch control agent is hydrophobic. It is presumed that the surface of the pitch is coated with hectorite by adhesion to the pitch due to the interaction, the adhesiveness of the pitch is reduced, and as a result the adhesion of the pitch is suppressed.

EXAMPLES The present invention will be described below based on examples, but the present invention is not limited to the following examples.

<Example 1>
Pure water is placed in a container equipped with a stirrer, and sodium acrylate homopolymer (Poly-NaAA) having a weight average molecular weight of 5,500 is added thereto so that the concentration becomes 0.3% by mass, and stirred to obtain 270 g. was obtained.
While stirring this solution at 700 rpm, 30 g of hectorite powder having a volume average particle size of 0.05 μm (measured by a laser diffraction scattering particle size analyzer, LS230 manufactured by Beckman Coulter) was added little by little. 300 g of an aqueous suspension (pitch control agent) was obtained by stirring for a minute. The viscosity of the resulting aqueous suspension was measured at 20° C. using a Brookfield C-type rotational viscometer (No. 3 rotor, 30 rpm) according to the procedure of JIS K7117-1 and found to be 1900 mPa s. rice field. The pH of the aqueous suspension was measured using a pH meter and found to be 10.
A water-soluble acrylate-based adhesive (A6001 manufactured by Resitex Co., Ltd.) is mixed with pure water at a ratio of 10 parts by mass to 100 parts by mass of pure water, and is evenly applied to the surface of the SUS mirror plate to a thickness of about 100 μm. did.
Phosphate buffer (pH 6.98 phosphoric acid obtained by mixing 1/15 M sodium dihydrogen phosphate (dihydrate) and 1/15 M disodium hydrogen phosphate (12 hydrate) at a mass ratio of 4:6 buffer solution) and the pitch control agent at a mass ratio of 9:1 to prepare a sample liquid.
After immersing the SUS mirror plate having the adhesive layer formed thereon in this liquid for 5 minutes, it was taken out and air-dried. Then, the stickiness of the mirror surface was checked by touch.
Further, the sample liquid was stirred at 20° C. using a shaker at 300 r/min for 30 seconds, and the presence or absence of bubbles was visually confirmed.

<Comparative Example 1>
After immersing the above-mentioned SUS mirror plate having the adhesive layer formed thereon in a phosphate buffer containing no pitch control agent for 5 minutes, it was taken out and air-dried.
Then, the tackiness of the surface of the mirror plate was checked by touch. The stickiness of the surface of the mirror plate at this time was defined as "5", while the non-sticky state was defined as "1". evaluated. When the degree of stickiness was between "5" and "1", it was ranked in three stages of "4", "3", and "2" from the larger degree. That is, when the stickiness evaluation is "1", there is no stickiness, and when the evaluation is "2" or more, the stickiness is generated. It means that the degree of stickiness increases from "2" to "5".

<Comparative Examples 2 to 4>
As a pitch control agent, in Comparative Example 2, a 10% by mass aqueous solution of a surfactant (ADEKA Pluronic L64) was used, and in Comparative Example 3, a 10% by mass aqueous solution of a cationic polymer (SNF FLOQUAT FL2949) was used. In Comparative Example 4, measurement was performed in the same manner as in Example 1, except that a dispersion of 10% by mass of talc in pure water was used.
Table 1 shows the results.

As is clear from Table 1, in Example 1 using the pitch control agent according to the embodiment of the present invention, a non-sticky state was achieved, but in Comparative Examples 1 to 4, stickiness remained. By contacting the aqueous suspension according to the embodiment of the present invention, it is believed that the exposed surface of the adhesive is covered with smectite, the adhesive strength of the exposed surface of the adhesive is reduced, and stickiness can be eliminated. . On the other hand, even if the adhesive is brought into contact with the liquid of the comparative example, the adhesive is not covered with smectite, so it is considered that the stickiness cannot be eliminated. From the above results, it can be seen that the pitch control agent according to the embodiment of the present invention can prevent pitch from adhering to paper, pulp, and manufacturing equipment thereof. Also, in Comparative Example 2, bubbles were generated, but in Example 1, no bubbles were generated. In other words, it can be seen that the pitch control agent according to the embodiment of the present invention suppresses the generation of foam, so that it is less likely to lower workability or cause trouble in the drainage process.

The pitch control agent of the present invention can be used in pulp or paper manufacturing processes. By using the pitch control agent, it is possible to effectively suppress and prevent the adhesion of pitch to pulp, paper, and manufacturing equipment thereof.

Claims (11)

A pitch control agent that is an aqueous hectorite suspension containing hectorite, a dispersant, and water,
The dispersant is an acrylate polymer having a weight average molecular weight of 1,000 to 10,000, and the hectorite content is 3 to 15 % by mass ,
A pitch control agent having a pH of 9-11. The pitch control agent according to claim 1, wherein the dispersant is an acrylate polymer having a weight average molecular weight of 1700-7000. The acrylate-based polymer is a homopolymer of acrylate, a copolymer of acrylate and 2-hydroxy-3-allyloxypropanesulfonic acid or a salt thereof, or an acrylate and 2-hydroxy- 3. The pitch control agent according to claim 2, which is a copolymer of 3-allyloxypropanesulfonic acid and its salt. 4. The pitch control agent according to claim 2, wherein the content of the acrylate-based polymer is 0.01 to 5% by mass. The pitch control agent according to any one of claims 1 to 4 , which has a viscosity of 400 to 3000 mPa·s at 20°C. The pitch control agent according to any one of claims 1 to 5 , further comprising a pH adjuster. The pitch control agent according to any one of claims 1 to 6 is applied to at least part of a paper manufacturing facility, at least a part of a pulp manufacturing facility, paper and / or pulp in a paper manufacturing facility, and pulp A method of pitch control comprising spraying at least one object of pulp in a manufacturing facility of . 8. The pitch control method according to claim 7 , wherein the cleaning water containing the pitch control agent is sprayed toward the object. 9. The pitch control method according to claim 8 , wherein the washing water contains the pitch control agent such that the solid content per liter of the washing water is 0.01 to 1000 mg. A pitch control method comprising adding the pitch control agent according to any one of claims 1 to 6 to pulp in a pulp or paper manufacturing process. The pitch control method according to claim 10 , wherein the pitch control agent is added to the pulp so that the mass of the solid content other than the pulp is 0.01 to 1250 g per 1 t of the mass of the pulp. .