JPH0328287A - Continuous preparation of emulsion type silicone antifoaming agent - Google Patents

Abstract

PURPOSE:To manufacture continuously an emulsion type silicone antifoaming agent and to improve production efficiency by mixing an organopolysiloxane and fine silica powder before emulsification and performing shearing and stirring in a specified manner. CONSTITUTION:A mixture of 100 pts.wt. silicone oil compd. consisting of 100 pts.wt. organopolysiloxane and 1-40 pts.wt. fine silica powder, 10-30 pts.wt. emulsifying agent, 10-500 pts.wt. water and 0-20 pts.wt. thickening agent is continuously fed in a cylindrical container furnished with a shearing stirring mechanism. While keeping this container under a pressurized condition of 0.5kg/cm G or higher, shearing stirring with a shear speed of 50 (1/sec) or larger is performed and a silicone emulsion is continuously taken out of a product output port of this container to obtain continuously the objective antifoaming agent. As the emulsifying agent used, a nonionic one is pref. from the viewpoint of dispersing effect and it is especially pref. that a hydrophilic surface active agent and a lipophilic surface active agent are used in parallel.

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to a method for producing an emulsion type silicone antifoaming agent, and particularly to a continuous production method.

It is known that emulsion-type silicone antifoaming agents can be obtained by emulsification of silicone oil compound in which finely divided inorganic fillers such as finely divided silica, titanium dioxide, ammonium oxide, etc. are dispersed in silicone oil (Tokuko Sho No. 58-7335, Special Publication No. 60-35163
No., JP 60-52845, JP 60-2628
No. 27, JP-A No. 62-277110).

The method for producing such an emulsion-type silicone antifoam agent is to mix the silicone oil compound described above with an emulsifier, other additives, and, if necessary, a thickener, and stir this mixture until a homogeneous dispersion is obtained. A common process is to pulverize the homogeneous dispersion, and then add water to the homogeneous dispersion while applying strong shearing force to form an emulsion. in this case,
Water was added to the above homogeneous dispersion liquid and 0.0% was added from the W/○ type. In order to invert the phase to /W type, it is necessary to use a mixer with a high shear rate, and such devices include a colloid droplet, a homogenizer, a homogenizer, etc.
-2886, Special Publication No. 60-35163). However, if we take as an example a method that uses a stirring device equipped with high-speed shearing stirring blades and a stator, usually called a homomixer, the emulsified material is sucked in at least through the holes provided in the stator, and the high-speed rotary blades Although it is necessary to undergo shearing action, as mentioned above, in order for the emulsified material to be sucked through the pores, the viscosity must be at most about 10,000 cp or less, so there is a limit to the viscosity of the dispersion that can be emulsified. was there.

In particular, since finely powdered silica is dispersed in the silicone antifoaming agent U, it has a thicker viscosity than the base silicone oil and is difficult to emulsify. Therefore, even if the viscosity of the antifoaming agent mixture is within an appropriate range, the viscosity may increase significantly when adding an emulsifier or a small amount of water to change the phase from W/○ type to O/W type. Because of this, there was a natural limit to the amount of kumikai that could be emulsified.

The above-mentioned drawbacks of the homomixer can also be pointed out with respect to colloidal mixers and homogenizers.

As a method to eliminate these drawbacks, (A) a stirring means capable of rotating the contents at a low speed throughout the container, (B) a disk-type stirring means having tooth-like protrusions on the periphery, and (c) a stator and high-speed turbine blades. A method for producing an emulsion-type silicone antifoaming agent using a composite stirring device equipped with a stirring means (Japanese Patent Application Laid-Open No. 182002/1983) is disclosed, and according to this method, a high viscosity silicone oil compound of 100,000 cp or more can be produced. It is said that it is also possible to emulsify.

However, when such an apparatus is used, it is not possible to continuously emulsify the silicone antifoam agent to obtain an emulsion, and sufficient production efficiency cannot be obtained.

On the other hand, as a continuous manufacturing method for silicone emulsion,
A manufacturing method is disclosed in which polydiorganosiloxane, an emulsifier, and water are continuously supplied into a cylindrical container equipped with a shear stirring mechanism, and a grease-like aqueous silicone liquid is continuously taken out (Tokuko Sho). 59-51565)
, boridiorganosiloxane, an emulsifier, and water in predetermined proportions, it is said that fine silica powder can be added together if necessary. However, this method continuously emulsifies silicone oil to provide a silicone emulsion that can be used as a mold release agent, polishing agent, medical ointment, cosmetic base, etc. Even if an emulsion containing fine silica powder is produced by adding it during production, the antifoaming effect is extremely weak because the silicone oil emulsion and the fine silica powder are individually dispersed. In some cases, it exhibits properties similar to a foam. As a result of intensive studies to solve the conventional drawbacks, the inventors of the present invention have developed a method to continuously produce an emulsion-type silicone antifoaming agent by mixing organoborisiloxane and finely powdered non-silica in advance prior to emulsification and dispersion. The present invention was achieved by discovering that this can be done.

<<Problems to be Solved by the Invention>> Therefore, an object of the present invention is to provide a continuous production method of an emulsion type silicone antifoaming agent.

<<Means for Solving the Problems>> The above object of the present invention is to provide (a) 100 parts by weight of a silicone oil compound consisting of 100 parts by weight of organoborisiloxane and 1 to 40 parts by weight of finely powdered silica, (b) an emulsifier. :■O~300! (c) water: 10 to 560 parts by weight, and (d) thickener: 0 to 20 parts by weight are continuously supplied into a cylindrical container equipped with a shear stirring mechanism, and the inside of the container is An emulsion product characterized in that the silicone emulsion is continuously taken out from the product outlet of the container after performing shear stirring at a shear rate of 500/sec or more while maintaining a pressurized state of 5 kg/dG or more. A continuous manufacturing method of type silicone defoamer was achieved.

The shear stirring mechanism is characterized in that at least three disks are arranged coaxially and at regular intervals on a rotating shaft coaxially installed with the cylindrical container.

The method of the present invention will be explained in detail below.

Used in the emulsion type silicone antifoaming agent of the present invention (
a) Part a of the organoborisiloxane has the general formula Rl1SiO. It is represented by TL, and Rl is a methyl group, an ethyl group, a proyl group,
Alkyl groups such as butyl groups, alkenyl groups such as vinyl groups and allyl groups, aryl groups such as phenyl groups and tolyl groups, and some or all of the hydrogen atoms bonded to the carbon atoms of these groups are halogen atoms, cyano groups, etc. a is the average of unsubstituted or substituted monovalent hydrocarbon groups having 1 to 20 carbon atoms, such as chloromethyl group, 3,3.3-trifluoropropyl group, cyanopropyl group, etc., substituted with value is 1
．． It is 9-2.1.

Examples of the organopolysiloxane include dimethylborisiloxane, diethylborisiloxane, methylphenylbolisiloxane, boridimethyl-boridiphenylsiloxane copolymer, polymethyl-3.3.3-trifluoropropylsiloxane, and polydimethyl-boridiphenylsiloxane. Examples include methylsiloxane.

Further, the fine powder unsilica added to this diorganoborisiloxane may be either dry silica or wet silica, which has been conventionally known as a silica-based filler, precipitated silica,
Silica xerogel, fumed silica, treated silica whose surface is treated with an organic silyl group, etc. can be used. Specific examples of such fine powder-free silica include Aerosil (trade name manufactured by Nippon Aerosil Co., Ltd.), Nipsil (trade name manufactured by Nippon Silica Co., Ltd.), Cabosil (trade name manufactured by Cabot Co., Ltd. in the United States), and Santocel (trade name manufactured by Monsando Chemical Co., Ltd. in the United States). Examples include product name). These finely powdered silicas preferably have a specific surface area of 50 rrf/g or more as measured by the BET method.

The blending amount of the fine powder silica is 1 to 40 parts by weight, preferably 3 to 20 parts by weight, based on 100 parts by weight of the diorganopolysiloxane. If it is less than 1 part by weight, its performance will not be fully exhibited, and if it is more than 40 parts by weight, the viscosity of the base oil will increase, resulting in poor workability and difficulty in handling.

The emulsifier used to form the antifoaming agent of the present invention may be nonionic, cationic, or anionic, but from the viewpoint of the dispersion effect of the antifoaming agent, nonionic emulsifier is preferable. In particular, it is preferable to use a hydrophilic surfactant and a lipophilic surfactant in combination. That is, if the hydrophilic-lipophilic balance (hereinafter abbreviated as HLB) is 3 or less, it will not function as a dispersion stabilizer, while if the HLB is 19 or more, the antifoaming property will decrease, so hydrophilic surfactants with an HLB of 8 to 20 agent and HL
A lipophilic surfactant whose B is 2 to 7 and whose HLB is 3 to 1.
It is preferable to mix it so that it has a range of 9.

Surfactants that can be used in the present invention include sorbitan fatty acid ester, glycerin fatty acid ester,
Examples include sig sugar fatty acid esters, higher fatty acid esters of polyoxyethylene compounds, higher alcohol ethers, alkylphenol condensates, alkyl quaternary ammonium salts, higher alkyl sulfonates, etc., especially those having 12 or more carbon atoms. Preferred are lipophilic surfactants such as sorbitan esters, glycerin esters, propylene glycol esters or polypropylene glycol of fatty acids of No. 18, such as sorbitan monostearate, sorbitan sesquioleate, monoglycerin monostearate, sorbitan sesquioleate, monoglycerin monostearate, oleate, triglycerine distearate,
Brobylene glycol monolaurate, stearic acid,
Examples include oleic acid. In addition, as hydrophilic surfactants, polyoxyethylene esters of fatty acids having 12 to 1 carbon atoms, polyoxyethylene sorbitan esters, polyoxyethylene higher alcohol ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene-borioxy Propylene block copolymers, polyoxyethylene castor oil esters, etc. are preferred, and specific examples thereof include polyoxyethylene sorbitan monolaurate, polyoxysorbitan distearate, polyoxyethylene glycerin monooleate, polyoxyethylene cetyl ether, Examples include sucrose monostearate, polyoxyethylene nonylphenyl ether, and polyoxyethylene tridecyl ether.

The amount of these emulsifiers used must be sufficient to make the silicone oil compound into emuldigon, but this amount is usually in the range of 10 to 300 parts by weight, particularly in the range of 20 to 300 parts by weight. A range of 200 tffi parts is preferred.

If (a) is 100 parts by weight and (b) is less than 10 parts by weight, it is difficult to emulsify, and even if emulsification is possible, the emulsion stability is poor, and oil may float to the surface or silica particles may form over time. If the amount exceeds 300 parts by weight, the particle size of the emulsion to be treated becomes too small, and the amount of free emulsifier increases, which impairs the antifoaming effect, which is not preferable.

By adding water to a compound mainly consisting of (a) a certain amount and ('b) prefecture, the emulsification phase is changed from W/O type to O/W type, reducing product cost and making it easier to use. In order to do this, in the present invention, 10 to 500 parts by weight of water is added as component (c) per 100 parts by weight of component (a).

If (a) 100 parts by weight or less (c) quantity is less than 10 parts by weight, emulsification phase inversion will not occur and a W/○ type emulsion will be produced, which is undesirable. If the amount is too large, the viscosity of the compound to be emulsified decreases and sufficient shear cannot be applied, so that the emulgitane produced has a large particle size and has poor stability, which is not preferable.

In addition, thickeners such as cellulose ethers such as carboxymethyl cellulose and carboxyethyl cellulose, partially saponified polyvinyl alcohol, crystalline cellulose, and sodium alginate may be added to the antifoaming agent of the present invention as necessary. . The amount of these thickeners added is usually O
~20 parts by weight. If it exceeds 20 parts by weight, the viscosity of the resulting emuldigon will become too high and it will be difficult to handle, and the antifoaming effect will be poor since the (d) preservative itself is a foam to begin with, which is not preferable.

Furthermore, a small amount of a bactericide can be appropriately added to the antifoaming agent of the present invention for the purpose of preservative. As disinfectants, sodium hypochlorite, sorbic acid, etc. are effective, and the amount added is based on the total amount of (a) silicone oil compound, which is a precept, and (b) an emulsifier, which is a certain amount. 0.05～
It is preferable to set it in the range of 0.5% of heavy background.

In the present invention, at least three disks are arranged coaxially and at regular intervals on a rotating shaft in order to continuously produce a certain emulsion-type antifoaming agent from the following precepts (a) to (d). It is characterized in that the emulsification operation is continuously performed using a cylindrical container equipped with an internal shearing stirring mechanism consisting of a mechanical structure.

FIG. 1 is a schematic cross-sectional view of a cylindrical container equipped with this shear stirring mechanism, and FIGS. 2(a) and (b) are A--A in FIG.
A cross-sectional view is shown.

In the figure, 1 is a cylindrical container, 2 is a rotating shaft, and 3 is a disc attached to the rotating shaft. It is desirable that at least three or more discs are provided on the rotating wheel. Figure 2 (a
) has no holes, and FIG. 2(b) has multiple holes 4 through which the liquid can pass, but from the viewpoint of the shear agitation effect, it is different from the disk with holes 4. It may also be combined with a disc without any holes. At least three discs 3 are required to be installed on the rotating shaft, and five or more discs are generally desirable. The distance (clearance) between the periphery of the disk 3 and the inner surface of the cylindrical container 1 should be 2 cm or less, as if it is too large, the shearing action between them will be insufficient and the desired emulsification will not be achieved. Well, generally 0.
It is desirable to set it as the range of 2-1.6 cm. Furthermore, a jacket for temperature regulation may be provided around the outer periphery of the cylindrical container.

It should be noted that for each certain amount of preparation, it is not necessary to premix or not premix in advance, and it is sufficient to supply each component at a predetermined ratio to one end of the cylindrical container. The supplied ingredients are sheared and mixed while passing between the disks to form a paste.

The rotation speed of the stirring mechanism needs to be such that the shear rate is 50 (1/sec) or more (preferably 500 to 1500 (1/sec)), but this shear rate in the present invention is as follows: Definitions shall apply.

The ingredients continuously charged by the above operation are mixed uniformly and finally turned into a paste-like aqueous liquid and taken out from the outlet 6. By pressurizing the raw material components from the charging port 5 with a bomb and adjusting the flow rate from the slit 7, which can be adjusted to m, so that the inside of the container 1 is pressurized to 0.5 kg/dG or more, the desired amount can be achieved. Uniform emulsification is successfully achieved.

Of course, the pressure inside the container is determined by the relationship between the amount of raw material supplied and the amount flowing out from the slit, and by adjusting these, the pressure inside the container can be maintained at a predetermined value.

The preferred range of the pressure inside the container is 1 to 4 kg/cTIG.

When operating under the above conditions, the raw material continuously supplied into the cylindrical container 1 from the inlet 5 or the amount of raw material flowing out from the slit 7 is regulated, and strong shear is generated by the high speed rotation of the circle Fi3 under pressurized conditions. As a result of stirring, extremely uniform and stable emulsification is achieved. Container pressure is 0.5kg/c
If it is lower than ++IG, strong shearing of the raw materials in the cylindrical container 1 will not occur, making it impossible to achieve the desired uniform emulsification. In addition, in order to achieve uniform mixing of the silicone oil compound and water, sand grains, glass beads, alumina particles, tungsten particles, etc. with a diameter of 0.5 mm are placed in the cylindrical container 1.
The stirrer may be operated with a charge of particles in the range ˜5 mm, which provides more intense shear agitation.

At this time, it is desirable to adjust the slit gap so that the filled particles do not pass through the slit 7 and flow out.

The assembled precepts of the present invention can be manufactured by continuously supplying the precepts (a) to (d) described above to the emulsifying device at a constant ratio; d) Providing the precepts separately also applies to (a) and (b) (c)
Mixture of (d), mixture of (a) and (b) and (c) and (a)
A mixture of (a) (b) (2) and (c), (a
) Mixture of @ ) (c) mixture, (a) and (c) and (c) (d) mixture, (a) and (b) (d) mixture and (c), etc. can do. Among these supply methods, a mixture of (a), (b), and (4) and (c) are used to control the emulsion particle size.
) is preferable. In addition, in this step, the ingredients (a) to (b) above can be heated to any temperature of 5 to 100"C, but the temperature during emulsification and dispersion is 3.
It is preferable to control the temperature within the range of 0 to 70°C in order to obtain emuldigons having a uniform and constant particle size.

<<Effects of the Invention>> As detailed above, according to the present invention, it is possible to carry out continuous production of an emulsion type silicone antifoaming agent, which has been difficult in the past, and therefore production efficiency can be significantly improved.

<<Examples> The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto.

Example 1. 88.0 kg of terminally trimethylsilyl-terminated dimethylborisiloxane with a viscosity of 1,000 cs at 25°C (trade name KF-96, manufactured by Shin-Etsu Chemical Co., Ltd.), as fine powder-free silica (trade name Nipsil VN3, manufactured by Nippon Silica Co., Ltd.) 12.
Mix Okg uniformly to make silicone oil compound A.
was manufactured.

Sorbitan monostearate (product name: Rheodol SP-SIO, manufactured by Kao Corporation; HLB=3.8125. Okg and polyoxyethylene sorbitan monooleate (trade name: Rheodol TW-0120, manufactured by Kao Corporation: HLB=15.0)
25.0 kg, carboxymethyl cellulose (trade name: Celogen WS-A, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) as a thickener 22.
0 kg was added, heated to 80°C, and premixed for 10 minutes using a stirrer. Next, this mixed solution was adjusted to 65°C, and then 300.0kg of water at 25°C was heated at a rate of 1.7kg/min using a metering bomb, and 300.0kg of water at 25°C was heated at 300.0kg using another metering bomb. The mixture was quantitatively supplied from the bottom side into a cylindrical container having seven disks at a rate of .0 kg/min.

The shear agitation was performed using a disc rotation speed of 2.00 rpm, a shear rate of 1,200 (1/sec), and a system pressure of 20.7 kg.
/c-dG, internal temperature: 40-45°C.

The viscosity of the white opaque emulsion obtained from the outlet of the container was determined to be 18.000 cp (at 25°C) using a BM rotational viscometer.
)Met.

When the electrical resistance was measured using a tester, it was confirmed that W1 was an O/W type emulsion in which the continuous phase was water because it showed conductivity. Also, the effective precept is 36.2% by weight.
Met. This emuldigon was stable and did not separate even when stored for 3 months at 40°C. 530 kg of dilution water was added to 470 kg of this high concentration emulsion and diluted and mixed to obtain antifoam emulsion A. The antifoam emulsion A is a white emulsion with an effective content of 17% by weight, a viscosity of 500 cp (25°C),
The volume average particle size is 12.6 am, and the volume distribution ratio of particles with a particle size of 6 to 18 μm is 72.3%, which is sharp.Not only does silicone oil not float, it can be stored at 40°C for 3 months. It was a stable emulsion that did not separate even when heated.

Comparative example 1. The rotation of the disc in Example 1 was performed at a shear rate of 40 (1/
When the mixture was stirred and mixed under the same conditions except that the speed was set to 200 cp (25° C.), a mixture with a viscosity of about 8.200 cp (25° C.) was obtained.

This was diluted with water at the same dilution ratio as in Example 1 to obtain emulsion B. This emulsion has a viscosity of 240 cp
(25°C), average particle size 21.8μm, particle size 6-1
The proportion of 8μm particles is 26.2%, which is a broad distribution, and oily substances float on the liquid surface, and when left at 40℃, the
Completely separated within days.

Comparative example 2. When stirring and mixing were carried out under the same conditions as in Example 1 except that the slit width of the cylindrical container was widened and the system internal pressure was set to 0.3 kg/c4G, a mixture with a viscosity of 13,000 cp (25°C) was obtained. This was diluted with water at the same dilution ratio as in Example 1 to obtain Emulsion C. This emulsion is
Viscosity is 320cp (25°C), average particle size is 18.9μ
m, the volume distribution ratio of particles with a particle size of 6 to 18 μm is 307
An oily substance with a broad distribution of 8% floated on the upper liquid surface, and when it was left at 40°C, it completely separated within 1 week. Comparative example 3. When an attempt was made to emulsify a mixed solution of the same antifoaming agent, emulsifier, and thickener as in Example 1 by stirring and mixing under the same conditions using a homo ξ xer, the paste-like material was found to have a high viscosity. Therefore, it was not possible to stir and obtain an emulsion.

Example 2. Trimethylsilyl-terminated dimethylpolysiloxane (KF
-96) 92.0kg, fine powder silica [Nibsil VN3
) 8.0 kg were uniformly mixed to produce silicone oil compound B.

To this silicone oil compound B, 25.0% of Rheodol SP-310 used in Example 1 was added as an emulsifier.
kg and Rheodor TV-0 1 20 to 25,Okg
Then, 0 kg of polybrobylene glycol (trade name: Uniol D-3 00120, manufactured by NOF Co., Ltd.) was added, heated to 80° C., and stirred and mixed until uniform. This mixture was then quantitatively fed into a mixing apparatus similar to that used in Example 1 at a similar rate. Shear agitation was carried out at a disc rotation speed of 2.00 Orpm and a shear rate of 1.
．． 200 (1/sec), pressure in the system: 1. 5kg
/cfflG, internal temperature: 40 to 45°C. As a result, a white, opaque, highly concentrated emulsion was continuously obtained from the outlet. The viscosity of this emulsion is 50,00
0cp (25°C), and was stable without separation even when stored for 3 months at 40°C. 530 kg of dilution water was added to 470 kg of this high concentration emulsion and diluted and mixed to obtain antifoam emulsion D.

The obtained antifoam emulsion D was a white emulsion with an effective content of 17% and a viscosity of 780 cp (2
5°C), volume average particle size is 10.2 μm, particle size is 6-1
The volume distribution ratio of 8 μm particles is 69.0%, which is sharp, and there is no floating silicone oil.
The emulsion was stable and did not separate even after being left at 40°C for 3 months. Comparative example 4. KF-96 with a viscosity of 1,00cs at 25°C
: Rheodor SP-SIO for 100kg: 25. Ok
g, Leodor TW 10120:25. Og and Uniol D-3000:20. After adding Okg, the mixture was heated to 80°C and stirred and mixed until uniform. Add this mixture to 6
After adjusting the temperature to 5° C., it was fed to the same apparatus as shown in Example 1 using a metering pump at a feeding rate of 1.7 kg/min.

Also, 25°C water: 290 kg and Nibsil VN3:
A liquid in which 10 kg was dispersed was similarly supplied using another metering bomb at a rate of 3.0 kg/min. The shear stirring conditions were the same as in Example 1. As a result, a white, opaque, highly concentrated emulsion with a viscosity of 5, OOOcp (25'C) was continuously obtained from the outlet.

Next, this emulsion was diluted and mixed in the same manner as in Example I to obtain a white emulsion E having an effective content of 17% by weight.

This emulsion has a viscosity of 1,700 cp (25°C
), the volume average particle size was 3.8 μm, and the volume distribution ratio of particles with a particle size of 6 μm or less was as small as 92.4%, and although there was no floating silicone oil, when left at 40″C Sedimentation of fine silica powder was observed in one week.

Example 3. When emulsions A to E obtained in Examples 1 to 2 and Comparative Examples 1 to 4 were subjected to defoaming tests using the following anionic and nonionic foaming liquids, the results shown in Table 1 were obtained.

[Defoaming test with anionic antifoaming liquid] Internal volume 1, OO
0.0 in the Od graduated cylinder. Weigh out 100 g of a 2% ion-exchanged aqueous solution of sodium oleate, and add 0.4
The change over time in the amount of foaming was investigated when air was continuously introduced at a rate of ii/min through a glass pole filter after adding g of antifoaming agent. The results are shown in Table-1.

/ / / / / [Defoaming test using nonionic foaming liquid] Internal volume L O
OO! 0.0 in II1 graduated cylinder. 3% polyoxyethylene nonyl phenyl ether (HLB=il.
O) 100 g of water was weighed out, 0.1 g of an antifoaming agent was added, and the change in foaming amount over time was examined in the same manner as above. The results are shown in Table 2. / From the results in Tables 1 and 2, it was demonstrated that the antifoaming agent of the present invention is extremely excellent in being able to maintain the antifoaming effect over a long period of time.

[Brief explanation of drawings]

FIG. 1 is a schematic longitudinal sectional view of a cylindrical container equipped with a shear stirring mechanism. 2(a) and 2) are sectional views taken along the line AA in FIG. 1. 1... Cylindrical container, 2... Rotating shaft, 3... Disc,
4... Hole 5... Supply port, 6... Product outlet 7...
slit

Claims (1)

[Claims] 1) (a) Silicone oil compound consisting of 100 parts by weight of organopolysiloxane and 1 to 40 parts by weight of finely powdered silica: 100 parts by weight (b) Emulsifier: 10 to 300 parts by weight (c) Water: 10 to 500 parts by weight (d) Thickener: A mixture consisting of 0 to 20 parts by weight is continuously supplied into a cylindrical container equipped with a shear stirring mechanism, and the inside of the container is heated at a pressure of 0.5 kg/cm^2G or more. An emulsion-type silicone antifoaming agent characterized in that shear stirring is performed at a shear rate of 50 (1/sec) or more while maintaining a pressurized state of , and the silicone emulsion is continuously taken out from the product outlet of the container. Continuous manufacturing method.