JP2019006622A - Aqueous suspension of hectorite - Google Patents

Abstract

To provide an aqueous suspension of hectorite that, even in a long-term storage, is inhibited from having an increased viscosity, gelation or precipitate production.SOLUTION: An aqueous suspension is provided which comprises a dispersant, water such as pure water, and 1 to 20 mass% of hectorite, the dispersant being composed of an acrylic acid salt-based polymer that is typified, for example, by a homopolymer of an acrylic acid salt or by a copolymer of an acrylic acid salt and 2-hydroxy-3-allyloxypropane sulfonic acid and/or its salt and that has a weight average molecular weight of 1000 to 10000. There is also provided a non-sticking agent for an unapplied coating material in a wet-type coating booth circulation water that includes the aqueous suspension.SELECTED DRAWING: None

Description

  The present invention relates to an aqueous suspension of hectorite. More specifically, the present invention relates to an aqueous suspension of hectorite in which viscosity increase, gelation, or precipitate formation is suppressed even during long-term storage.

Slurries of layered silicates such as hectorite and bentonite are expected to be used in various fields.
For example, U.S. Patent No. 6,057,059 discloses a slurry containing a hectorite clay material, a diluent, a water soluble polyphosphate water conditioning agent, alumina, montmorillonite clay and an antifoaming agent to prevent sticking and clarification of paint spray booth effluent. It is proposed to be used for pumping.

  Patent Document 2 discloses a water-soluble organic polymer having an organic acid salt structure or an organic acid anion structure, a silicate such as hectorite, and a dispersant having a weight average molecular weight of 200 to 20,000 and having hydrolysis resistance. A hydrogel-forming composition capable of forming a self-supporting hydrogel comprising:

  Patent Document 3 discloses a dispersion aid comprising at least 10% by weight of a layered silicate such as bentonite, an aqueous suspension medium, and at least one free acid form polyacrylic acid having an average molecular weight of about 200 to about 70,000. A slurry or suspension containing

JP-A 61-157388 WO 2014/046136 A Special table 2009-500279

  An object of the present invention is to provide an aqueous suspension of hectorite in which viscosity increase, gelation or precipitate formation is suppressed even during long-term storage.

  As a result of studies to achieve the above object, the present invention including the following embodiments has been completed.

[1] An aqueous suspension containing a dispersant composed of an acrylate polymer having a weight average molecular weight of 1000 to 10,000, water, and 1 to 20% by mass of hectorite.

[2] The acrylate polymer is a homopolymer of acrylate, or a copolymer of acrylate with 2-hydroxy-3-allyloxypropane sulfonic acid and / or a salt thereof. The aqueous suspension described.
[3] The aqueous suspension according to [1] or [2], wherein the pH is 7 to 11.
[4] The aqueous suspension according to any one of [1] to [3], wherein the content of the acrylate polymer is 0.01 to 5% by mass.
[5] The aqueous suspension according to any one of [1] to [4], wherein the viscosity is 400 to 3000 mPa · s.

[6] A non-adhesive agent for an uncoated paint in a wet coating booth circulating water comprising the aqueous suspension according to any one of [1] to [5].

The aqueous suspension of the present invention has almost no increase in viscosity or gelation even during long-term storage, and hardly produces precipitates.
The detackifying agent comprising the aqueous suspension of the present invention can be pumped and is effective for detackifying uncoated paint in the wet coating booth circulating water. The aqueous suspension of the present invention is also useful as a rheology control agent, a thickener, a viscosity modifier, a binder, a film-forming agent, a fabric softener, a papermaking fixing auxiliary additive, and the like.

  Bentonite, that is, clay mainly composed of montmorillonite, is a kind of dioctahedral squemite, and two trivalent cations such as Al are incorporated into the octahedron. On the other hand, hectorite is a kind of trihedral scumetite, and three divalent cations such as Ca and Mg are incorporated in the octahedron. When using phosphate-based dispersants or free acid carboxylic acid-based dispersants as described in prior art documents, low-solubility aluminum phosphate, calcium phosphate, magnesium phosphate, etc. may precipitate or hydrogel Or the stability of the aqueous suspension may be impaired. On the other hand, the aqueous suspension according to the present invention hardly generates precipitates, does not gel, and is excellent in storage stability.

  The aqueous suspension according to the present invention contains hectorite, a dispersant and water.

  The hectorite used in the present invention is a kind of trioctahedral type scumite. Hectorite may be naturally occurring or artificially synthesized. Synthetic hectorites include BYK's Laponite EP, RD, RDS, SL25, and S482; Corp Chemical's Lucentite SWN and SWF; Elementis Specialties' Benton SD-3, HC, EW, MA , LT and the like.

  The hectorite used in the present invention has a volume average particle diameter of preferably 0.01 to 2 μm, more preferably 0.01 to 1 μm. If the particle size is too large, it tends to be difficult to maintain a suspended state. If the particle size is too small, the particles tend to settle or gel due to aggregation.

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

The dispersant used in the present invention is an acrylate polymer.
The acrylate polymer is preferably an acrylate homopolymer or a copolymer of acrylate and other monomers.
Examples of the acrylate include sodium acrylate, potassium acrylate, and ammonium acrylate. In the acrylate polymer, the amount of the structural unit derived from the acrylate is preferably 70 to 100 mol% with respect to all the structural units.

  Other monomers include acrylic acid, methacrylic acid and salts thereof, itaconic acid and salts thereof, maleic acid, sodium maleate, ammonium maleate; acrylic acid esters such as methyl acrylate and ethyl acrylate; methyl methacrylate , Methacrylates such as ethyl methacrylate; aromatic vinyl such as styrene, α-methylstyrene, p-methylstyrene; acrylonitrile, methacrylonitrile; acrylamide, methacrylamide, N-methylolacrylamide; N-propylmaleimide, N- Cyclohexylmaleimide, N-o-chlorophenylmaleimide; 2-hydroxy-3-allyloxypropanesulfonic acid and its salt, 2-acrylamido-2-methylpropanesulfonic acid and its salt; isobutylene, acetic acid Or the like can be mentioned a nil. Of these other monomers, 2-hydroxy-3-allyloxypropane sulfonic acid and salts thereof are preferred.

  The weight average molecular weight of the acrylate polymer is 1000 to 10,000, preferably 1200 to 9000, more preferably 1500 to 8000, and still more preferably 1700 to 7000. 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 viscosity of an aqueous suspension during storage.

  The amount of the acrylate polymer contained in the aqueous suspension of the present invention is preferably 0.01 to 5% by mass, more preferably 0.09 to 3% by mass, based on the mass of the aqueous suspension. Yes, preferably from 0.1 to 25 mass%, more preferably from 0.3 to 20 mass%, based on the mass of hectorite.

  The water used in the present invention 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 still more preferably 0 to 10 mg. / L, most preferably 0 mg / l. In the present invention, pure water such as RO water, deionized water, and distilled water is most preferably used. The amount of water contained in the aqueous suspension of the present invention is preferably 75 to 98.89% by mass, more preferably 82 to 96.9% by mass.

  The aqueous suspension of the present invention is not particularly limited by its preparation method. For example, a predetermined amount of an acrylate polymer is added to pure water at room temperature in a container and stirred to obtain a solution. While stirring the solution vigorously, a predetermined amount of hectorite is added little by little. An aqueous suspension can be obtained by stirring until the substance adhering to the inner wall of the container is uniformly washed away with a small amount of pure water.

  The aqueous suspension of the present invention has a viscosity of preferably 400 to 3000 mPa · s, more preferably 700 to 2000 mPa · s. Moreover, the pH of the aqueous suspension of the present invention is preferably 7 to 11, more preferably 9 to 11. When the pH is low, the salt form in the acrylate polymer tends to decrease, the free acid form tends to increase, and the edge part with a positive charge forms an edge-to-face bond (card house structure) The gelation tends to proceed easily.

  The aqueous suspension of the present invention can be used, for example, as a tack free agent, a rheology control agent and the like.

The detackifying agent of the present invention can be added to wet paint booth circulating water and used to reduce the tackiness of unpainted paint.
In order to remove uncoated paint in the wet paint booth circulating water, in addition to the tackifier of the present invention, a cationic agent such as a cationic coagulant and a cationic flocculant is added to the wet paint booth circulating water. It is preferable.

  Cationic coagulants include cationic inorganic coagulants such as aluminum sulfate (sulfuric acid band), polyaluminum chloride (PAC), basic aluminum chloride, aluminum nitrate, etc .; cationic organic coagulant, polyethylene Imine, cation-modified polyacrylamide, polyamine, polyamine sulfone, polyamide, polyalkylene / polyamine, amine cross-linked polycondensate, polydimethylaminoethyl acrylate, dimethyldiallylammonium chloride polymer (DADMAC), polycondensation of alkylamine and epichlorohydrin Polycondensates of alkylene dichloride and polyalkylene polyamines, polycondensates of dicyandiamide and formalin, homopolymers or copolymers of dimethylaminoethyl methacrylate (DAM), poly Examples include cationic polymer coagulants such as nylamidine, copolymers of diallyldimethylammonium chloride and acrylamide, polycondensates of melamine and aldehyde, polycondensates of dicyandiamide and aldehyde, and polycondensates of dicyandiamide and diethylenetriamine. be able to. Examples of the alkylamine in the polycondensate of alkylamine and epichlorohydrin include monomethylamine, monoethylamine, dimethylamine, and diethylamine. Examples of the aldehyde in the melamine / aldehyde condensate and the dicyandiamide / aldehyde polycondensate include formaldehyde, acetaldehyde, propionaldehyde, paraformaldehyde which is a trimer of formaldehyde. The cationic polymer coagulant has, for example, a weight average molecular weight of preferably 1,000 to 1,000,000, more preferably 5,000 to 300,000. These cationic coagulants may be used alone or in combination of two or more.

  As the polymer flocculant made of a cationic polymer, a polymer having a cationic structural unit derived from a quaternary ammonium salt of (meth) acrylic acid ester (for example, acrylamide / [2- (acryloyloxy) ethyl] benzyldimethylammonium) Copolymer of chloride / [2- (acryloyloxy) ethyl] trimethylammonium chloride, Copolymerization of acrylamide / [3- (acryloyloxy) propyl] benzyldimethylammonium chloride / [2- (acryloyloxy) ethyl] trimethylammonium chloride Polymer, acrylamide / [2- (acryloyloxy) ethyl] benzyldimethylammonium chloride / [3- (acryloyloxy) propyl] trimethylammonium chloride copolymer, acrylic / [3- (acryloyloxy) propyl] benzyl dimethyl ammonium chloride / [3- (acryloyloxy) propyl] trimethylammonium chloride copolymer, etc.), polyamino alkyl acrylates, poly-amino alkyl methacrylate, and the like. The weight average molecular weight of the cationic polymer is preferably 6 million or more, more preferably 7 million to 11 million.

  In order to efficiently remove the unpainted paint in the wet paint booth circulating water, other chemicals can be further added to the wet paint booth circulating water. Examples of other agents include non-cationic detackifying agents, non-cationic coagulants, non-cationic polymer flocculants, and pH adjusters.

  The non-cationic detackifying agent is a known compound capable of detackifying an uncoated paint in the wet booth circulating water. Although known ones can be used as the non-cationic detackifying agent, an anionic detackifying agent is preferable from the viewpoint of detackifying performance, and a phenolic resin or a carboxylic acid polymer is more preferable. The non-cationic detackifying agent may be used alone or in combination of two or more.

  Examples of the non-cationic coagulant include sodium alginate; sodium aluminate, bentonite, sepiolite; biocoagulants such as TKF04 strain and BF04.

  Examples of non-cationic polymer flocculants include sodium polyacrylate, polyacrylic acid soda / amide derivative, polyacrylamide partial hydrolyzate, partially sulfomethylated polyacrylamide, poly (2-acrylamide) -2-methylpropane sulfate, etc. A polymer flocculant composed of an anionic polymer, and a polymer flocculant composed of an amphoteric polymer such as a copolymer of (meth) acrylamide, quaternary ammonium alkyl (meth) acrylate and sodium (meth) acrylate. it can. The non-cationic polymer flocculant has a weight average molecular weight of preferably more than 1 million, more preferably 5 million or more. The polymer flocculant made of an amphoteric polymer has an anion / cation molar ratio of preferably 0.2 to 2.0.

  Next, an Example and a comparative example are shown and this invention is demonstrated more concretely. However, the following examples show only one embodiment of the present invention, and the present invention is not limited to the following examples.

Example 1
Into a container equipped with a stirrer, pure water at 23 ° C. is added, and sodium acrylate homopolymer (Poly-NaAA) having a weight average molecular weight of about 5500 is added to this so as to have a concentration of 0.3% by mass and stirred. To obtain a solution. While stirring this solution at 700 rpm, 30 g of hectorite powder was added little by little. The substance adhering to the inner wall of the container was washed with a small amount of pure water and stirred for 40 minutes until uniform, thereby obtaining 300 g of an aqueous suspension.
The aqueous suspension was left at room temperature and 40 ° C., respectively. When one day, one week, one month, and three months had passed since the standing, the aqueous suspension was visually observed to evaluate the presence or absence of fluidity. The results of fluidity when left at room temperature are shown in Table 1. The fluidity when left at 40 ° C. was the same as the results shown in Table 1.

Examples 2 and 3
An aqueous suspension was obtained in the same manner as in Example 1 except that the concentration of sodium acrylate homopolymer (Poly-NaAA) was changed to 0.5% by mass and 0.7% by mass, and the presence or absence of fluidity was evaluated. . The results of fluidity when left at room temperature are shown in Table 1. The fluidity when left at 40 ° C. was the same as the results shown in Table 1.

Example 4
Aqueous suspension was prepared in the same manner as in Example 1 except that the sodium acrylate homopolymer was changed to a copolymer of sodium acrylate and 2-hydroxy-3-allyloxypropanesulfonic acid (Poly-NaAA / HAPS, weight average molecular weight 5000). A suspension was obtained and evaluated for fluidity. The results of fluidity when left at room temperature are shown in Table 1. The fluidity when left at 40 ° C. was the same as the results shown in Table 1.

Examples 5-6
The following was the same as Example 1 except that the concentration of the copolymer of sodium acrylate and 2-hydroxy-3-allyloxypropanesulfonic acid (Poly-NaAA / HAPS) was changed to 0.5% by mass and 0.7% by mass. An aqueous suspension was obtained by the method, and the presence or absence of fluidity was evaluated. The results of fluidity when left at room temperature are shown in Table 1. In the evaluation up to the time when one week passed, the fluidity when left at 40 ° C. was the same as the result shown in Table 1. In the evaluation when one month passed, the fluidity when left at 40 ° C. was “none”. Therefore, the subsequent evaluation was not performed.

Examples 7-9
An aqueous suspension was obtained in the same manner as in Examples 1 to 3 except that the sodium acrylate homopolymer having a weight average molecular weight of 5500 was changed to a sodium acrylate homopolymer having a weight average molecular weight of 2000, and the presence or absence of fluidity was evaluated. The results of fluidity when left at room temperature are shown in Table 1. The fluidity when left at 40 ° C. was the same as the results shown in Table 1.

Comparative Examples 1-3
An aqueous suspension was obtained in the same manner as in Examples 1 to 3 except that the sodium acrylate homopolymer having a weight average molecular weight of 5500 was changed to a sodium acrylate homopolymer having a weight average molecular weight of 20000, and the presence or absence of fluidity was evaluated. The results of fluidity when left at room temperature are shown in Table 1. Since the fluidity was “none” in the evaluation after 1 day, the subsequent evaluation was not performed.

Comparative Example 4
An aqueous suspension was obtained in the same manner as in Example 2 except that sodium acrylate homopolymer having a weight average molecular weight of 5500 was changed to acrylic acid homopolymer having a weight average molecular weight of 10,000 (Poly-AA), and the presence or absence of fluidity was evaluated. did. The results of fluidity when left at room temperature are shown in Table 1. Since the liquidity was “none” on the first day, no further evaluation was made.

Comparative Example 5
A sodium acrylate homopolymer having a weight average molecular weight of 5500 was changed to a sodium maleate homopolymer having a weight average molecular weight of 1000 (Poly-NaMA), and the concentration was changed to 0.25% by mass. A suspension was obtained and evaluated for fluidity. The results of fluidity when left at room temperature are shown in Table 1. Since the liquidity was “none” on the first day, no further evaluation was made.

Example 10
Into a vessel equipped with a stirrer, pure water at 23 ° C. was added, a sodium acrylate homopolymer having a weight average molecular weight of 5500 was added to a concentration of 0.475% by mass, and a solution was obtained by stirring. . While this solution was stirred at 700 rpm, 28.5 g of hectorite powder was added little by little. The substance adhering to the inner wall of the container was washed with a small amount of pure water and stirred for 40 minutes until uniform, thereby obtaining 300 g of an aqueous suspension.
The obtained aqueous suspension was put into a glass bottle with a lid, set in a BL type rotational viscometer (manufactured by Toki Sangyo), and rotor No. The viscosity was measured under the conditions of 3, 23 ° C., 30 rpm → coefficient 40. The aqueous suspension was left at ambient temperature. Viscosity was measured when 1 day, 2 days, and 15 days had passed since the standing. Moreover, when three weeks passed, the presence or absence of the deposit was evaluated by visual observation. The results are shown in Table 2.

Example 11
An aqueous suspension was obtained in the same manner as in Example 10 except that the amount of hectorite powder was changed to 24 g and the concentration of the sodium acrylate homopolymer was changed to 0.4% by mass, and the viscosity was measured and visually observed. It was. The results are shown in Table 2.

Example 12
An aqueous suspension was obtained in the same manner as in Example 10 except that the sodium acrylate homopolymer was changed to a copolymer of sodium acrylate and 2-hydroxy-3-allyloxypropanesulfonic acid (weight average molecular weight 5000). Measurement and visual observation were performed. The results are shown in Table 2.

Example 13
Except for changing the amount of hectorite powder to 24 g and changing the concentration of the copolymer of sodium acrylate and 2-hydroxy-3-allyloxypropanesulfonic acid to 0.4% by mass, A turbid liquid was obtained, and viscosity measurement and visual observation were performed. The results are shown in Table 2.

  From the above results, it can be seen that the aqueous suspension of the present invention has almost no increase in viscosity even when stored for a long period of time, and can maintain the fluidity that can be conveyed by a pump.

Claims (6)

  An aqueous suspension containing a dispersant composed of an acrylate polymer having a weight average molecular weight of 1000 to 10,000, water, and 1 to 20% by mass of hectorite.   The aqueous solution according to claim 1, wherein the acrylate polymer is a homopolymer of acrylate, or a copolymer of acrylate and 2-hydroxy-3-allyloxypropanesulfonic acid and / or a salt thereof. Suspension.   The aqueous suspension according to claim 1 or 2, wherein the pH is 7-11.   The aqueous suspension according to any one of claims 1 to 3, wherein the content of the acrylate polymer is 0.01 to 5% by mass.   The aqueous suspension according to any one of claims 1 to 4, wherein the viscosity is 400 to 3000 mPa · s.   A non-tackifying agent for uncoated paint in a wet coating booth circulating water comprising the aqueous suspension according to any one of claims 1 to 5.