JP2015174002A - Defoaming agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a defoaming agent which exhibits excellent defoaming properties (foam breaking/suppressing effect) even when being stored for a long period.SOLUTION: A defoaming agent which is composed of fumed silica (A) and polyether compound (B) and is characterized in that a content of the fumed silica (A) is 0.3 to 15 wt.% and a content of the polyether compound (B) is 85 to 99.7 wt.% based on the molecular weight of the fumed silica (A) and the polyether compound (B) is used. It is preferable that wettability of methanol (M value) of the fumed silica (A) is 35 to 75. It is preferable that a number average primary particle size of the fumed silica (A) is 5 to 30 nm.

Description

  The present invention relates to an antifoaming agent.

Conventionally, “(A) the following general formula (1) (wherein R ¹ and R ² each independently represents a linear or branched alkyl group or alkenyl group having 6 to 22 carbon atoms, X and Z are each Independently represents an acyl group, an ether group, Y represents a polyoxyethylene polyoxypropylene group, and the polyoxyethylene group is 50 mol% or less in Y.)
R ¹ —X— (Y) —Z—R ² (1)
An antifoaming agent composition comprising (B) an organopolysiloxane and (C) hydrophobic silica is known (Patent Document 1).

JP 2004-057872 A

The conventional antifoaming agent has a problem that sufficient antifoaming properties (foam breaking and foam suppressing effects) cannot be obtained. In particular, there is a problem that the antifoaming property decreases with time.
An object of the present invention is to provide an antifoaming agent that exhibits excellent antifoaming properties (foam breaking and foam suppressing effects) even after long-term storage.

  The antifoaming agent of the present invention is characterized by comprising fumed silica (A) and a polyether compound (B). Based on the weight of the fumed silica (A) and the polyether compound (B), fumed silica ( The gist is that the content of A) is 0.3 to 15% by weight and the content of the polyether compound (B) is 85 to 99.7% by weight.

  A feature of the method for producing a latex of the present invention is that it includes a demonomer step in which the above-mentioned antifoaming agent is added to the latex dispersion and the unreacted monomer is distilled off under reduced pressure.

  The antifoaming agent of the present invention exhibits excellent antifoaming properties (foam breaking and antifoaming effects) even after long-term storage.

  According to the method for producing a latex of the present invention, since the above-mentioned antifoaming agent is used, even if the antifoaming agent is stored for a long period of time, excellent antifoaming properties (foam breaking and foam suppressing effects) are exhibited. Therefore, the productivity of latex can be further improved.

  As the fumed silica (A), hydrophilic fumed silica and hydrophobic fumed silica can be used. Of these, hydrophobic fumed silica is preferred from the viewpoint of antifoaming properties.

  Fumed silica (A) is readily available from the market. As a trade name of hydrophobic fumed silica, the AEROSIL series (R972, RX200, RY200, R202, R805, etc., Nippon Aerosil Co., Ltd., “AEROSIL” is a registered trademark of Evonik Degussa M. Becher. The same shall apply hereinafter.) ; REOLOSIL series (MT-10, DM-10, DM-20S, etc., Tokuyama Co., Ltd., “REOLOSIL” is a registered trademark of the same company, the same shall apply hereinafter); HDK series (HDKH15, HDKH18, etc., Asahi Kasei Wacker) Silicone Co., Ltd., “HDK” is a registered trademark of Wacker Chemie AG. The same shall apply hereinafter.); And CAB-O-SIL series (TS-720, TS-622, TS-382, etc., Cabot Carbon Corporation, “CAB-O-SIL” is key Botsuto co -.. Pareishiyan is a registered trademark of the same applies hereinafter), and the like.

  The trade names of hydrophilic fumed silica include AEROSIL series (50, 130, 200, 300, R812, etc.); REOLOSIL series (QS-10, QS-30, QS-40, S-102, etc., Tokuyama Corporation) HDK series (HDKN20, HDKS13, etc., Asahi Kasei Wacker Silicone Co., Ltd.) CAB-O-SIL series (EH-5, S-5, etc., Cabot Carbon);

  The methanol wettability (M value) of the fumed silica (A) is preferably 35 to 75, and more preferably 40 to 70.

  The M value is an index representing the degree of hydrophobicity, and means the volume% of a uniform dispersion having the smallest methanol concentration among several water / methanol mixed solutions having different concentrations, and is measured as follows. Is the value to be It can be said that the higher this value, the higher the hydrophobicity.

<Measuring method of methanol wettability (M value)>
A mixed water / methanol solution is prepared in which the methanol concentration is changed at intervals of 5% by volume, and this is placed in a test tube having a volume of 10 ml. Next, 0.2 g of a measurement sample is put, the test tube is capped, and the sample is turned upside down 20 times, and then left to stand for 1 to 2 minutes. Then, the aggregate is observed. The concentration (volume%) of methanol in the dispersion having the smallest methanol concentration among the dispersions wet and uniformly dispersed is defined as M value.

  As for the number average primary particle diameter (nm) of fumed silica (A), 5-30 are preferable, More preferably, it is 12-16.

  The number average primary particle size is obtained by measuring the particle size of at least 2500 particles randomly from a measurement sample on a transmission electron microscope image, and obtaining the average primary particle size by number average.

  As a polyether compound (B), it is a compound which has a some ether bond in a molecule | numerator, and what is liquid at 25 degreeC can be used, A polyoxyalkylene compound can illustrate preferably.

  The polyether compound (B) includes a polymer having a oxyalkylene group having 2 to 18 carbon atoms as a unit. The polyether compound (B1) represented by the general formula (1) is represented by the general formula (2). Represented by the polyether compound (B2), the polyether compound (B3) represented by the general formula (3), the polyether compound (B4) represented by the general formula (4), and the general formula (5). Preferably, at least one selected from the group consisting of polyether compounds (B5) can be exemplified.

R ¹ is a reaction residue of an active hydrogen compound having 1 to 25 carbon atoms, R ² and R ³ are monovalent organic groups having 1 to 24 carbon atoms, R ⁴ is a divalent organic group having 1 to 24 carbon atoms, R ⁵ is a hydroxyl group or a monovalent organic group having 1 to 24 carbon atoms, AO and OA are oxyalkylene groups having 2 to 18 carbon atoms, or glycidol, a reaction residue of an alkyl glycidyl ether or alkenyl glycidyl ether having 4 to 18 carbon atoms. Represents a group, and in (AO) n, the proportion of the oxyethylene group is 0 to 20% by weight, n is an integer of 1 to 100, and when a plurality of n are present in one molecule, they are the same or different. S is an integer of 1 to 10, p is an integer of 0 to 10, q is an integer of 0 to 9, r is an integer of 0 to 9, m is an integer of 0 to 9, p + r is 1 to 10 P + q + r is an integer from 1 to 10, p + q + r + m is It is 10.

The reaction residue (R ¹ ) of an active hydrogen compound having 1 to 25 carbon atoms means a reaction residue obtained by removing active hydrogen from an active hydrogen compound having 1 to 25 carbon atoms.
Examples of the active hydrogen-containing compound having 1 to 25 carbon atoms include compounds containing at least one hydroxyl group (—OH), imino group (—NH—), amino group (—NH ₂ ) and / or carboxyl group (—COOH). And includes alcohols, amides, amines, carboxylic acids, hydroxycarboxylic acids and aminocarboxylic acids.

  Examples of alcohol include monool (methanol, butanol, stearyl alcohol, oleyl alcohol and isostearyl alcohol) and polyol (ethylene glycol, propylene glycol, glycerin, diglycerin, tetraglycerin, trimethylolpropane, pentaerythritol, dipentaerythritol, Dihydroxyacetone, fructose, glucose, mannose, galactose, sucrose, lactose, trehalose, etc.).

  Examples of the amide include monoamide (formic acid amide, propionic acid amide, stearyl amide, etc.), polyamide (malonic acid diamide, ethylene bisoctylamide, etc.) and the like.

  Examples of amines include monoamines (such as dimethylamine, ethylamine, aniline and stearylamine) and polyamines (such as ethylenediamine, diethylenetriamine and triethylenetetramine).

  Examples of the carboxylic acid include monocarboxylic acids (such as acetic acid, stearic acid, oleic acid, and benzoic acid) and polycarboxylic acids (such as maleic acid and hexanedioic acid).

  Examples of the hydroxycarboxylic acid include hydroxyacetic acid, tartaric acid, malic acid and 12-hydroxystearic acid.

  Examples of aminocarboxylic acids include glycine, 4-aminobutyric acid, 6-aminohexanoic acid and 12-aminolauric acid.

Examples of the monovalent organic group (R ² , R ³ ) having 1 to 24 carbon atoms include an alkyl group (R), an alkenyl group (R ′), an acyl group (—COR), an aroyl group (—COR ′), N -Alkylcarbamoyl group (-CONHR), N-alkenylcarbamoyl group (-CONHR '), alkylcarbonylamino group (-NHCOR), alkenylcarbonylamino group (-NHCOR'), alkylcarboxyamino group (alkylcarbamate group, -NHCOOR) ) And an alkenylcarboxyamino group (alkenyl carbamate group, —NHCOOR ′).

  Examples of the alkyl group (R) include methyl, ethyl, isopropyl, t-butyl, octyl, 2-ethylhexyl, dodecyl and octadecyl.

  Examples of the alkenyl group (R ′) include vinyl, propenyl, hexenyl, isooctenyl, dodecenyl and octadecenyl.

Among the hydroxyl groups or monovalent organic groups having 1 to 24 carbon atoms (R ⁵ ), the monovalent organic groups having 1 to 24 carbon atoms include the same organic groups as described above.

Examples of the divalent organic group (R ⁴ ) having 1 to 24 carbon atoms include an alkylene group (T), an alkenylene group (T ′), a 1-oxaalkylene group (—OT—), and a 1-oxaalkenylene group (—OT). '-), 1-oxoalkylene group (-COT-), 1-oxoalkenylene group (-COT'-), 1-aza-2-oxoalkylene group (-NHCOT-), 1-aza-2-oxoalkenylene Group (-NHCOT'-), 1-oxo-2-azaalkylene group (-CONHT-), 1-oxo-2-azaalkenylene group (-CONHT'-), 1-aza-2-oxo-3-oxa An alkylene group (—NHCOOT—) and a 1-aza-2-oxo-3-oxaalkenylene group (—NHCOOT′—) are included.

  Examples of the alkylene group (T) include methylene, ethylene, isobutylene, 1,10-decylene, 1,2-decylene, 1,12-dodecylene, 1,2-dodecylene and 1,2-octadecylene.

  Examples of the alkenylene group (T ′) include ethynylene, isobutynylene, 1,10-decynylene, 1-octylethynylene, 1-octenylethylene, 1,12-dodecynylene, and 1-octadecenylethylene.

  Of the oxyalkylene group having 2 to 18 carbon atoms or the reaction residue (AO, OA) of glycidol, alkyl glycidyl ether having 4 to 18 carbon atoms or alkenyl glycidyl ether, the oxyalkylene group having 2 to 18 carbon atoms is oxy Examples include ethylene, oxypropylene, oxybutylene, oxyisobutylene, oxy-1,2-decylene, oxy-1,12-dodecylene, oxy-1,2-dodecylene, and oxy-1,2-octadecylene.

  Further, among (AO, OA), examples of the alkyl glycidyl ether having 4 to 18 carbon atoms include methyl glycidyl ether, ethyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, dodecyl glycidyl ether, and octadecyl glycidyl ether. It is done.

  Moreover, among (AO, OA), as alkenyl glycidyl ether having 5 to 18 carbon atoms, vinyl glycidyl ether, butenyl glycidyl ether, 2-ethylhexenyl glycidyl ether, dodecenyl glycidyl ether and octadecenyl glycidyl ether are used. Examples include ether.

  The proportion of oxyethylene groups in (AO) n is 0 to 20 wt%, preferably 0 to 18 wt%, more preferably 0 to 15 wt%, based on the weight of all (AO) n. %. When the oxyethylene group is contained, the lower limit of the proportion of the oxyethylene group is preferably 3% by weight, more preferably 5% by weight, particularly preferably 8% by weight based on the weight of all (AO) n. It is.

  n is an integer of 1 to 100, preferably an integer of 2 to 75, and more preferably an integer of 3 to 50.

  The polyether compound (B1) represented by the general formula (1) includes polyoxypropylene monobutyl ether, propylene oxide ethylene oxide block adduct of tetradecyl alcohol, propylene oxide ethylene oxide block adduct of trimethylolpropane, polyoxypropylene glycol , Polyoxyethylene polyoxypropylene glycol (block addition), glycerin propylene oxide adduct, glycerin ethylene oxide propylene oxide block adduct, monododecylamine propylene oxide adduct, polyoxypropylene glycol monooleate, glycerin propylene oxide 2 -Ethylhexyl glycidyl block adduct, propylene oxide butylene oxide block adduct of sucrose and Ethylene propylene oxide block adduct of pentaerythritol.

  The polyether compound (B2) represented by the general formula (2) includes polyoxypropylene monobutyl ether monooleate, distearate of polyoxyethylene polyoxypropylene glycol (block addition), and monostearate of propylene oxide adduct of glycerin. And monomethyl ether of ethylene oxide propylene oxide block adduct of maleic acid and mono N-hexylcarbamic acid ester of propylene oxide adduct of sucrose.

  Examples of the polyether compound (B3) represented by the general formula (3) include propylene oxide adduct of ethylenebisstearylamide, propylene oxide adduct of glycerin monostearyl ester, and propylene oxide of sucrose mono (2-ethylhexylglycidyl) ether Examples include adduct mono N-decylcarbamate.

  Examples of the polyether compound (B4) represented by the general formula (4) include a monooleate of a castor oil propylene oxide adduct and a propylene oxide adduct of glycerin bis (12-hydroxystearate).

  As the polyether compound (B5) represented by the general formula (5), a reaction product of polyoxypropylene monolauryl ether, polyoxypropylene glycol and hexamethylene diisocyanate, polyoxypropylene monostearyl ether and polyoxyethylene polyoxy Examples include reactants of propylene glycol (block addition) and xylene diisocyanate.

  Among these, the polyether compound (B1) represented by the general formula (1) and the polyether compound (B2) represented by the general formula (2) are preferable from the viewpoint of defoaming property and the like.

  The content (% by weight) of fumed silica (A) is preferably 0.3 to 15, more preferably 1 to 10, based on the weight of fumed silica (A) and the polyether compound (B). Preferably it is 1.5-8. The content (% by weight) of the polyether compound (B) is preferably 85 to 99.7, more preferably 90 to 99, particularly based on the weight of the fumed silica (A) and the polyether compound (B). Preferably it is 92-98.5. Within these ranges, the defoaming property and handleability are further improved.

  The antifoaming agent of the present invention can further contain water (C). By containing water, the initial diffusibility into the aqueous foaming liquid can be increased, and the initial foam breaking property can be remarkably improved. It also has the effect of reducing the danger of ignition and increasing the safety in handling. As water, distilled water, ion exchange water, tap water, industrial water, well water, spring water, river water, and the like can be used. Among these, tap water, industrial water, ion exchange water and distilled water are preferable, and ion exchange water and distilled water are more preferable.

  When water (C) is contained, the content (% by weight) of water (C) is preferably 1 to 10, more preferably based on the weight of fumed silica (A) and the polyether compound (B). 1 to 6, particularly preferably 2 to 4.

  The antifoaming agent of the present invention may further contain at least one dispersoid selected from the group consisting of metal soap (D), synthetic resin (E), amide (F) and wax (G). . However, it is preferable not to contain such a dispersoid in order to exhibit excellent antifoaming properties even when stored for a long period of time.

  The metal soap (D) includes a salt of a fatty acid having 12 to 22 carbon atoms and a metal (alkaline earth metal, aluminum, manganese, cobalt, lead, chromium, copper, iron, nickel, etc.), and aluminum stearate. , Calcium stearate, zinc laurate and magnesium behenate.

  Synthetic resins (E) include (co) polymers of ethylenically unsaturated monomers (polystyrene, polyacrylonitrile, polymethyl methacrylate and styrene / acrylonitrile copolymers, etc.) and polymers of polycondensation monomers (polyurethane, polyester and Polyamide, etc.).

  As the synthetic resin (E), a synthetic resin obtained by a technique such as emulsion polymerization may be used, or a monomer may be polymerized in the polyether compound (B) to prepare the synthetic resin (E).

  The amide (F) includes monoamide and bisamide. The bisamide includes a reaction product of an alkylenediamine having 1 to 6 carbon atoms and a fatty acid having 10 to 22 carbon atoms, such as ethylene bisstearylamide, ethylene bispalmitylamide, ethylene bismyristylamide, ethylene bislaurylamide, ethylene. Examples include bisoleylamide, methylenebisstearylamide, hexamethylenebisstearylamide, ethylene-bis-12-hydroxystearylamide, hexamethylene-bis-12-hydroxystearylamide, and the like.

  Examples of the monoamide include fatty acid amides having 10 to 22 carbon atoms, and examples include stearyl amide, N-stearyl stearyl amide, and N-methyl stearyl amide.

  The wax (G) includes a wax-like substance (natural wax, synthetic wax, oil or the like) having a melting point of at least 50 ° C. (preferably 70 to 160 ° C.) and not dispersible in the polyether compound. At least one selected from the group consisting of (A1) petroleum wax, (A2) synthetic wax, (A3) plant wax, and (A4) modified wax obtained by modifying these waxes, having a melting point in the temperature range of 70 to 160 ° C. Can be preferably exemplified.

  (A1) Examples of petroleum wax include microcrystalline wax and paraffin wax.

  (A2) Examples of the synthetic wax include Fischer-Tropsch wax and polyethylene wax.

  (A3) Examples of plant wax include carnauba wax and wood wax.

  (A4) Examples of modified waxes obtained by modifying these waxes include maleic acid-modified polyethylene oxide wax and polyethylene oxide wax.

  When the dispersoid is contained, the particle diameter (μm) of the dispersoid is preferably 0.1 to 10, more preferably 0.12 to 9, and particularly preferably 0.15 to 8.

  When these dispersoids are contained, their content (% by weight) is preferably 0.1 to 10, more preferably 0, based on the weight of the fumed silica (A) and the polyether compound (B). .15-9, particularly preferably 0.2-8, most preferably 0.3-7.5.

  The antifoaming agent of the present invention may further contain an organopolysiloxane (H). However, it is preferable not to contain such an organopolysiloxane in order to exhibit excellent defoaming properties even when stored for a long time.

Polyorganosiloxane (H) includes polydimethylsiloxane and modified polyorganosiloxane.
Examples of the polydimethylsiloxane include polydimethylsiloxane having a kinematic viscosity of 5 to 10,000 (mm ² / s, 25 ° C.), and also includes cyclooctamethyltetrasiloxane.
As the modified polyorganosiloxane, part of the methyl group of the above polydimethylsiloxane is an alkyl group having 2 to 6 carbon atoms, an alkoxyl group having 2 to 4 carbon atoms, a phenyl group, a hydrogen atom, halogen (such as chlorine and bromine). An atom, an alkoxy polyoxyalkyleneoxypropyl group (alkoxy having 1 to 6 carbon atoms, an alkylene having 2 to 3 carbon atoms), an alkoxy polyoxyalkylene group (alkoxy having 1 to 6 carbon atoms, an alkylene having 2 to 3 carbon atoms) and And / or those substituted with an aminoalkyl group having 2 to 6 carbon atoms.

  When the organopolysiloxane (H) is contained, the content (% by weight) of the organopolysiloxane (H) is 0.01 to 0 based on the weight of the fumed silica (A) and the polyether compound (B). .1 is preferred.

  The antifoaming agent of the present invention is effective for water-based foaming liquid {for example, drainage, papermaking process white water, water-based paint, etc.}, but can be particularly effective for latex polymerization dispersion. Among latex polymerization dispersions, this is particularly effective for dispersions in a demonomer process in which unreacted monomers are distilled off under reduced pressure.

  That is, the antifoaming agent of the present invention is suitable for a method for producing a latex comprising a demonomer step in which the above-mentioned antifoaming agent is added to a latex dispersion and the unreacted monomer is distilled off under reduced pressure.

  The antifoaming agent of the present invention can be added to the foaming liquid by a batch addition method, a continuous addition method, an intermittent addition method, or a method in which a foam measuring device and an antifoaming agent adding device are linked. Moreover, either one place addition and multipoint addition may be sufficient. Further, upon addition, it may be diluted with a suitable diluent solvent or water.

  The usage-amount of the antifoamer of this invention can be suitably determined according to the kind of foaming liquid and a foaming state. For example, when applied to the monomer removal step, the amount is about 0.005 to 0.2% by weight based on the weight of the latex.

  EXAMPLES Next, although an Example demonstrates this invention further, this invention is not limited to this. Hereinafter, unless otherwise specified, “part” means “part by weight” and “%” means “% by weight”.

The following products (a1) to (a3) were used as the fumed silica (A).
Fumed silica (a1) [M value 50, number average primary particle diameter 16 nm]
Fumed silica (a2) [M value 40, number average primary particle diameter 16 nm]
Fumed silica (a3) [M value 70, number average primary particle size 12 nm]

  As water (C), ion-exchanged water (c1) and distilled water (c2) were used.

<Example 1>
In a vessel capable of stirring, 15 parts of fumed silica (a1), polyether compound (b1) {New Pole PE-61, Sanyo Chemical Industries, Ltd., polyoxyethylene (5 mol), polyoxypropylene (30 mol) Block polymer; “New Pole” is a registered trademark of the company. } 835 parts and polyether compound (b2) {Newpol TL-4500N, Sanyo Chemical Industries, Ltd., trimethylolpropane ethylene oxide (10 mol) / propylene oxide (68 mol) block adduct} 150 parts with stirring for 30 minutes And the antifoamer (1) of this invention was obtained.

<Example 2>
30 parts of fumed silica (a2) 78 parts, polyether compound (b3) {New Paul LB-1715 (oleic acid ester of polyoxypropylene (40 mol) glycol monobutyl ether)} 922 parts in a stirrable container The antifoaming agent (2) of the present invention was obtained by stirring and mixing for minutes.

<Example 3>
30 parts of fumed silica (a3) 80 parts, polyether compound (b4) {Newpol LB-1715, Sanyo Chemical Industries, polyoxypropylene (40 mol) monobutyl ether} 30 parts in a stirrable container The antifoaming agent (3) of the present invention was obtained by stirring and mixing for minutes.

<Example 4>
In a stirrable container, 25 parts of fumed silica (a2), polyether compound (b5) {Sanix GP-3000, Sanyo Chemical Industries, glycerin propylene oxide (43 mol) adduct} 925 parts, poly 50 parts of ether compound (b6) {oleic acid ester of castor oil propylene oxide (30 mol) adduct} was stirred and mixed for 30 minutes to obtain antifoaming agent (4) of the present invention.

<Example 5>
In a stirrable vessel, 150 parts of fumed silica (a1), polyether compound (b7) {800 parts of glycerin ethylene oxide (3 mol) / 2-ethylhexyl glycidyl ether (6 mol) block adduct}, polyether compound (B8) {obtained by reacting 250 parts of polyoxypropylene (34 mol) glycol, 231 parts of polyoxyethylene (3 mol) polyoxypropylene (14 mol) myristyl ether and 16.8 parts of hexamethylene diisocyanate Polyether compound} 50 parts was stirred and mixed for 30 minutes to obtain an antifoaming agent (5) of the present invention.

<Example 6>
In a stirrable vessel, 20 parts of fumed silica (a1) and polyether compound (b9) {390 mol adduct of sucrose polyoxypropylene}, 490 parts of polyether compound (b1), polyether (b10) { 100 parts of an ethylene oxide (117 mol) / propylene oxide (16 mol) block adduct of pentaerythritol} and 20 parts of water (c1) were stirred and mixed for 30 minutes to obtain an antifoaming agent (6) of the present invention.

<Example 7>
In a stirrable container, 40 parts of fumed silica (a1), 890 parts of a polyether compound (b4), 70 parts of a polyether compound (b9), and 40 parts of water (c2) are stirred and mixed for 30 minutes. Antifoaming agent (7) was obtained.

<Example 8>
In a stirrable container, 80 parts of fumed silica (a3) and 920 parts of the polyether compound (b12) {distearate of the polyether compound (b1)} are stirred and mixed for 30 minutes, and the antifoaming agent (8 )

<Example 9>
In a stirrable container, 60 parts of fumed silica (a3) and polyether compound (b13) {polyoxypropylene (50 mol) monobutyl ether} 600 parts, polyether compound (b14) {New Pole GP-600, Sanyo Kasei Kogyo Co., Ltd., 9 parts adduct of glycerin propylene oxide} 340 parts and 80 parts of water (c1) were stirred and mixed for 30 minutes to obtain the antifoaming agent (9) of the present invention.

<Comparative Examples 1-9>
Comparative defoamers (I1) to (I9) were prepared in the same manner as in Examples 1 to 9, except that fumed silica (a1) to (a3) were not used.

<Comparative Example 10>
In a stirrable container, 50 parts of hydrophobic silica {Nipseal SS-100, Tosoh Silica Co., Ltd., hydrophobic silica synthesized by a wet precipitation method} and 950 parts of a polyether compound (b5) are stirred and mixed for 30 minutes. Thus, an antifoaming agent (I10) for comparison was obtained.

<Comparative Example 11>
In a stirrable container, 50 parts of hydrophobic silica {Nipseal G-0251, Tosoh Silica Co., Ltd., hydrophobic silica synthesized by a wet precipitation method} and 950 parts of a polyether compound (b2) are stirred and mixed for 30 minutes. Thus, a defoaming agent (I11) for comparison was obtained.

<Evaluation of antifoaming property (1)>
Using the antifoaming agents (1) to (9) and (I1) to (I11) obtained in Examples 1 to 9 and Comparative Examples 1 to 11, the antifoaming property was evaluated as follows, and the evaluation results Are shown in Table 1.

<Adjustment of foam test solution>
In a stainless beaker, 83.2 parts of SB latex [L-1924, manufactured by Asahi Kasei Chemicals Corporation], 16.6 parts of ion-exchanged water, and sodium alkylbenzenesulfonate [Newlex R, manufactured by NOF Corporation] 0.2 parts Was added and stirred uniformly for 10 minutes to obtain a foam test solution.

<Defoaming test method>
In a state where a glass 500 ml graduated cylinder (hereinafter referred to as a foaming tube) is stood, a 95 ml scale of the foaming tube is immersed in a water bath whose temperature is adjusted to 80 ° C, and foaming whose temperature is adjusted to 80 ° C is immersed in this foaming tube. Add 100 ml of the test solution, insert the diffuser stone to the bottom of the foamed tube and perform bubbling with nitrogen at 500 ml / min to foam the foamed test solution. When the foam and the volume of the foamed solution reach 220 mL, erase with a micropipette. 50 μL of foaming agent (500 ppm as the concentration relative to the foam test solution) was dropped into the foam test solution, and the nitrogen and bubbling of the foam test solution were continued. Readings were taken after 5 and 10 minutes. A smaller value means that the defoaming property is higher, which is preferable. A blank test (blank) was also performed in the same manner as described above except that the antifoaming agent was not dropped.

表中、「−」はメスシリンダーで測定可能な５００ｍｌを超えており、測定不能であったことを示す(以下、同じである。）。

In the table, "-" indicates that the measurement exceeds 500 ml that can be measured with a graduated cylinder, and measurement was impossible (the same applies hereinafter).

<Evaluation of antifoaming property (2)>
After putting antifoaming agents (1) to (9) and (I1) to (I11) obtained in Examples 1 to 9 and Comparative Examples 1 to 11 into a glass sealed container for 3 months at 25 ° C. Defoamability was evaluated in the same manner as the evaluation of foamability (1)>, and the evaluation results are shown in Table 2.

  The antifoaming agent of the present invention exhibited excellent antifoaming properties (foam breaking and foam suppressing effect) even after long-term storage, as compared with a comparative antifoaming agent.

The antifoaming agent of the present invention is suitable for processing and wastewater treatment in fields such as the chemical industry, food industry, petroleum industry, textile industry, paper pulp industry or pharmaceutical industry.

Claims (6)

It consists of fumed silica (A) and a polyether compound (B), and based on the weight of fumed silica (A) and a polyether compound (B), content of fumed silica (A) is 0.3-15. An antifoaming agent characterized in that the content of the polyether compound (B) is 85 to 99.7% by weight. The antifoaming agent according to claim 1, wherein the fumed silica (A) has a methanol wettability (M value) of 35 to 75. The antifoaming agent according to claim 1 or 2, wherein the number average primary particle size of the fumed silica (A) is 5 to 30 nm. The polyether compound (B) is a polyether compound (B1) represented by the general formula (1), a polyether compound (B2) represented by the general formula (2), and a poly compound represented by the general formula (3). It is at least one selected from the group consisting of an ether compound (B3), a polyether compound (B4) represented by general formula (4), and a polyether compound (B5) represented by general formula (5). The antifoamer in any one of 1-3.

R ¹ is a reaction residue of an active hydrogen compound having 1 to 25 carbon atoms, R ² and R ³ are monovalent organic groups having 1 to 24 carbon atoms, R ⁴ is a divalent organic group having 1 to 24 carbon atoms, R ⁵ is a hydroxyl group or a monovalent organic group having 1 to 24 carbon atoms, AO and OA are oxyalkylene groups having 2 to 18 carbon atoms, glycidol, alkyl glycidyl ether or alkenyl glycidyl ether having 4 to 18 carbon atoms, Represents a group, and in (AO) n, the proportion of the oxyethylene group is 0 to 20% by weight, n is an integer of 1 to 100, and when a plurality of n are present in one molecule, they are the same or different. S is an integer of 1 to 10, p is an integer of 0 to 10, q is an integer of 0 to 9, r is an integer of 0 to 9, m is an integer of 0 to 9, p + r is 1 to 10 P + q + r is an integer from 1 to 10, p + q + r + m is It is 10. Furthermore, content of water (C) containing water (C) is 1-10 weight% based on the weight of fumed silica (A) and a polyether compound (B). Defoaming agent as described. A method for producing a latex, comprising a de-monomer step of adding the antifoaming agent according to any one of claims 1 to 5 to a latex polymerization dispersion and distilling off unreacted monomers under reduced pressure.