JPH0239921B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an emulsion-type silicone antifoaming agent, and particularly to an emulsion-type silicone antifoaming agent that has excellent foam-breaking properties and defoaming durability. (Prior Art) It is known that an emulsion-type silicone antifoaming agent can be obtained by emulsifying a silicone oil compound in which finely powdered inorganic fillers such as silica, titanium dioxide, and aluminum oxide are dispersed in silicone oil. The foam-breaking properties of this product,
Antifoam retention and resistance to acids and alkalis are primarily determined by the properties of the silicone oil compound, and emulsion is considered simply as a means to hydrophilize and disperse the silicone oil compound. Therefore, improvement of this emulsion-type silicone antifoaming agent has focused on the modification of silicone oil compounds. (Refer to Japanese Patent Publication No. 35556/1983), emulsion of a composition prepared by adding organohydrodiene polysiloxane, silica, and a catalyst to organopolysiloxane under alkali-resistant conditions. (see Japanese Patent Application Laid-Open No. 57-48307),
In addition, it has been proposed to improve storage stability by adding a silazane-treated silica filler to a silicone oil suspension containing an emulsifier (see Japanese Patent Application Laid-open No. 52-2887). All of these are aimed at either foam-breaking properties, defoaming persistence, or storage stability, and are not intended to improve these properties at the same time. Conventionally, emulsion-type silicone antifoaming agents have been modified to improve the stability of the emulsion by adjusting the amount of emulsifier; is stabilized, but has the disadvantage that initial defoaming and foam-breaking properties deteriorate.If the amount of emulsifier is minimized and phase inversion is carried out, the initial defoaming and foam-breaking properties become coarser, resulting in poor initial defoaming and foam-breaking properties. However, since the emulsion particles aggregate, the defoaming effect does not last long. In addition, the emulsion formed by controlling the amount of emulsifier to the optimum level also has a constant particle size because, for example, there are differences in temperature and water temperature between summer and winter, and the amount of phase inversion water and phase inversion temperature are not appropriate. It has the disadvantage that its properties cannot be specified. (Structure of the Invention) The present invention relates to an emulsion-type silicone antifoaming agent that solves these disadvantages. The emulsion is characterized in that the volume distribution ratio of particles having a volume average particle diameter of 6 μm or more and 18 μm or less is 40% or more. That is, as a result of various studies on emulsion-type silicone antifoaming agents that are stable and have excellent foam-breaking properties and long-lasting defoaming properties, the present inventors found that an emulsion obtained by using a silicone oil compound with an emulsifier was obtained. If the volume average particle diameter is 6 to 18 μm and the particles within this particle size range account for 40% or more of the total,
A silicone antifoaming agent with an extremely good balance between foam-breaking properties and defoaming persistence is obtained, and this product approaches the foam membrane and adsorbs any foaming.
The present invention was completed by discovering that the foam penetrates into the foam and breaks the foam, and the effect is maintained for a long time. The organopolysiloxane constituting the emerald type silicone antifoaming agent of the present invention has the general formula R ¹ is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, an alkenyl group such as a vinyl group or an allyl group, an aryl group such as a phenyl group or a tolyl group, or a carbon atom of these groups. Part or all of the bonded hydrogen atoms are halogen atoms,
Chloromethyl group substituted with cyano group etc., 3,
Same or different carbon atoms 1 to 20, such as 3,3-trifluoropropyl group, cyanopropyl group, etc.
The unsubstituted or substituted monovalent hydrocarbon group a has an average value of 1.9 to 2.1, and this includes dimethylpolysiloxane, diethylpolysiloxane, methylphenylpolysiloxane, polydimethyl-polysiloxane, Examples include diphenylsiloxane copolymer, polymethyl-3,3,3-trifluoropropylsiloxane, and polydimethyl-chloropropylmethylsiloxane. Further, the fine powder silica added to this organopolysiloxane may be either dry silica or wet silica, which has been conventionally known as a silica-based filler, and includes precipitated silica, silica xerogel, fumed silica, and the surfaces thereof. Examples include treated silica, which is treated with organic silyl groups.
Specific examples include Aerosil (trade name manufactured by Nippon Aerosil Co., Ltd.), Nipsil (trade name manufactured by Nippon Silica Co., Ltd.), Kyabosil (trade name manufactured by Kyabot Co., Ltd. in the United States), and Santocel (trade name manufactured by Montsanto Chemical Company in the United States). . The fine powdered silica preferably has a specific surface area of 50 m ² /g or more by the BET method, which is the same as the above-mentioned organopolysiloxane.
If it is less than 1 part by weight, its performance will not be fully demonstrated, and if it is more than 40 parts by weight, the viscosity of the base oil will increase, making it difficult to handle, so use 1 to 40 parts by weight. The amount is preferably 3 to 20 parts by weight. Next, nonionic, cationic, and anionic emulsifiers can be used to form this antifoaming agent, but from the standpoint of antifoaming and dispersion effects, nonionic emulsifiers are preferred. Preferably, and more preferably, a hydrophilic surfactant and a lipophilic surfactant are used in combination; however, if the HLB is 3 or less, it will not function as a dispersion stabilizer, and if the HLB is 19 or more, it will not function as an antifoaming agent. Since it reduces the
A mixture of a hydrophilic surfactant of ~20 and a lipophilic surfactant with an HLB of 2-7 so that the HLB is in the range of 3-19 is preferred. Such surfactants include sorbitan fatty acid ester,
Examples include glycerin fatty acid esters, sucrose fatty acid esters, higher fatty acid esters of polyoxyethylene compounds, higher alcohol esters, alkylphenol condensates, alkyl quaternary ammonium salts, higher alkyl sulfonates, etc. Preferably, a lipophilic surfactant such as sorbitan ester, glycerin ester, propylene glycol ester or polypropylene glycol of a fatty acid having 12 to 18 carbon atoms is used, and such active agents include sorbitan monostearate, sorbitan, etc. Examples include sesquioleate, monoglycerin monooleate, doliglycerin distearate, propylene glycol monolaurate, stearic acid, and oleic acid. In addition, this surfactant has 12 to 18 carbon atoms.
polyoxyethylene ester of fatty acids, polyoxyethylene sorbitan ester, polyoxyethylene fatty acid alcohol ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene-polyoxypropylene block copolymer, polyoxyethylene castor oil ester, etc. Hydrophilic surfactants may also be used, including polyoxyethylene monostearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan distearate, polyoxyethylene glycerin monooleate, polyoxyethylene cetyl ether, Examples include sucrose monostearate, polyoxyethylene nonylphenyl ether, and polyoxyethylene tridecyl ether. The amount of this emulsifier added must be sufficient to make the silicone oil compound into an emulsion, but this is usually 1% to the total amount of the organopolysiloxane composition and emulsifier. -60% by weight, with a preferred range of 10-60% by weight. Further, a thickening agent may be added to the antifoaming agent of the present invention if necessary, and includes cellulose ethers such as carboxymethyl cellulose and carboxyethyl cellulose, partially saponified polyvinyl alcohol, crystalline cellulose, and sodium alginate. These are exemplified, but the amount thereof is usually 5% by weight or less based on the total amount of the above-mentioned organopolysiloxane composition and emulsifier. It is optional to add a small amount of a disinfectant to this antifoaming agent for the purpose of preservatives, and sodium hypochlorite, sorbic acid, etc. are said to be effective as disinfectants, but the amount added depends on the organ. 0.05-0.5% based on the total amount of polysiloxane composition and emulsifier
The range of The emulsion-type silicone antifoaming agent of the present invention can be obtained by mixing predetermined amounts of the above-mentioned components and stirring uniformly.
~18 μm, and the volume distribution ratio of particles within this particle size range is essential to be 40% or more. Such emulsions are for example (i)
The organopolysiloxane composition and the emulsifier are uniformly mixed and dispersed, (ii) the thickener is dissolved in water, and (iii) step
Add the water required for phase inversion and the predetermined amount of the thickened water obtained in (ii) to the mixture obtained in (i), and use a pulverizer such as a homomixer, homogenizer, or colloid mill. to make a homogeneous emulsion, and then (iv)
It can be obtained by mixing the above emulsion with water or the thickened water obtained in (ii). However, when mixing the organopolysiloxane composition and the emulsifier in step (i), if the ratio of emulsifier/organopolysiloxane composition is 0.1 or less, the volume average particle diameter of the emulsion particles in the emulsion produced becomes coarse. If the antifoaming agent deviates from the scope of the invention, the antifoaming durability of this antifoaming agent will deteriorate, and the stability of the emulsion itself will also become very poor, causing emulsion particles to settle over time and causing problems with silicone oil compounds. If this ratio is set to 2.0 or more, the volume average particle diameter of the emulsion particles in the generated emulsion becomes finer, deviating from the range of the present invention of 6 μm or more, and this antifoaming agent becomes This ratio is preferably set in the range of 0.1 to 2.0, since this results in poor defoaming properties and a small foam-breaking effect on large bubbles with a thick foam film. In addition, in the emulsification in this step (iv), the mixture of the organopolysiloxane composition and the emulsifier may be heated as necessary, and the temperature of the water added to this dispersion may be 5 to 50°C. As such, it is best to control the temperature during emulsification (phase inversion temperature) between 30 and 70°C, and by controlling the temperature during phase inversion in this way, it is possible to obtain emulsions with the above particle size distribution with good reproducibility. However, an effective method is to adjust the particle size distribution of which the particle size distribution is already known so that it falls within the scope of the present invention. Note that the amount of water required for phase inversion in step (iii) above is usually the amount necessary for the emulsion to change from w/o to o/w, but the amount of water for phase inversion also changes the particle size. The distribution can be controlled, and the particle size distribution can also be controlled by the dispersion method during phase inversion, that is, the type of mixer device and stirring conditions. The emulsion-type silicone antifoam agent of the present invention produced by the method described above has particularly excellent foam-breaking properties and defoaming durability, has a good foam-breaking effect on foams with a large surface film thickness, and the emulsion itself is stable. Therefore, this product is particularly useful for defoaming water systems in food, fermentation, pulp and paper manufacturing processes, and wastewater treatment processes. Next, examples of the present invention will be given. Parts in the examples are parts by weight, and viscosity is the value measured at 25°C. The defoaming test using anionic and nonionic foaming liquids in the examples is as follows. This shows the test results according to the method. [Defoaming test using anionic foaming liquid] Weigh out 100g of an ion exchange aqueous solution of 0.2% sodium oleate in a graduated cylinder with an internal volume of 1000ml,
After adding a predetermined amount of antifoaming agent to this, air was continuously introduced at a rate of 1/min through a glass ball filter, and the change over time in the amount of foaming was examined. [Defoaming test using nonionic foaming liquid] 0.3% polyoxyethylene nonyl phenyl ether (HLB
= 11.0) 100 g of water was weighed out, a predetermined amount of antifoaming agent was added, and the change over time in the amount of foaming was examined in the same manner as above. Example 1 94 parts of dimethylpolysiloxane with a viscosity of 1000 cS, in which both ends of the molecular chain are blocked with trimethylsilyl groups, and 6 parts of silica filler Aerosil-300 (trade name, manufactured by Nippon Aerosil Co., Ltd.) are placed in two containers. to make silicone oil compound A, which is then mixed with the lipophilic emulsifier sorbitan monostearate.

[Table] Example 2, Comparative Example 1 94 parts of dimethylpolysiloxane with a viscosity of 10,000 cS in which both ends of the molecular chain are blocked with monohydroxydimethylsilyl groups, and fine silica powder/Nipsil VN-
3 [trade name manufactured by Nippon Silica Co., Ltd.] and 6 parts are mixed in a container of 2 to make silicone oil compound B, and then polypropylene glycol and
Uniol D-1000 [trade name manufactured by NOF Corporation], lipophilic emulsifier Rheodol SP-S10 [mentioned above] and hydrophilic emulsifier Rheodol TW-O120 [mentioned above] were used in the second stage.
The amount shown in the table was added, and the mixture was stirred at 70 to 80°C for 15 minutes to prepare a premixed liquid, which was then adjusted to 60°C. Also, in a separate container, add 800 parts of water and carboxymethylcellulose/cellogen as a thickener.
Add 10 parts of WS-C [trade name manufactured by Daiichi Kogyo Seiyaku Co., Ltd.] to make thickened water, adjust the temperature to 20°C, and then gradually add it to the premix obtained above. The emulsions were emulsified by stirring at high speed with a mixer, finely pulverized with a homogenizer, and filtered to create emulsions B to H. The volume particle system distribution of the particles in these emulsions was investigated, and the results are also listed in Table 2. The exact results were obtained.

[Table] Example 3, Comparative Example 2 10 parts of water was placed in a cleaned container and heated to approximately 60-70°C, followed by adding lipophilic emulsifier Rheodol SP-S10
[Previously] Part 1 and hydrophilic emulsifier/Rheodol TW-
Add 1 part of O120 [previously] with stirring, and lower the temperature.
The mixture was stirred for an additional 15 minutes at 60°C. Next, the silicone oil compound prepared in Example 1 was added to this while maintaining it at a temperature of 60°C.
After adding 10 parts of A and stirring for 15 minutes, the mixture was pulverized to 4 to 6 mils using a colloid mill to prepare a premix. Additionally, add 48.2 parts of water to thickener and cerogen.
Add and dissolve 0.8 parts of WS-C [previously mentioned], add the above premix adjusted to 55-60℃, mix and stir for about 20 minutes, add 28.8 parts of dilution water, and then dissolve. The mixture was passed through a Manton-Gaulin type homogenizer once under a pressure of 300 kg/cm ² to be finely pulverized and then filtered to make an emulsion. Four types of emulsions I to L were prepared by changing the emulsions as shown in Table 3, and their volumetric particle distributions were examined, and the results shown in Table 3 were obtained.

【table】

[Table] Example 4 Emulsions B to L produced in Examples 2 and 3
When emulsions M, N, O, and P were prepared by mixing them in the proportions shown in Table 4, the volume particle size distribution of the emulsion particles in these emulsions was as follows.
As listed in the table, Example 3, Comparative Example 2
The antifoaming test results of the emulsions I to L obtained in the above and the individually obtained emulsions M to P using an anionic foaming liquid or a nonionic foaming liquid are as shown in Tables 5 and 6.

【table】

【table】

[Table] Example 5 27 parts of dimethylpolysiloxane with a viscosity of 600 cS, in which both ends of the molecular chain are blocked with trimethylsilyl groups, and 3 parts of silica filler R-972 [trade name manufactured by Nippon Aerosil Co., Ltd.] were mixed. Lipophilic emulsifier Rheodol SP- is added to the obtained silicone oil compound.
S10 [previously] Part 3 and hydrophilic emulsifier/Rheodol TW
Add 2 parts of -O120 [previously mentioned] and 5 parts of glycerin fatty acid ester Excel 200 [trade name manufactured by Kao Soap Co., Ltd.] and heat and stir at 60°C for 3 hours to make a premix. After adding the entire amount, the emulsion was stirred with a homomixer to form an emulsion, and the volume particle size of the emulsion particles of this emulsion and its antifoaming properties were investigated. 7th
The results shown in the table were obtained.

【table】

Claims (1)

[Claims] 1 In an emulsion consisting of a composition mainly composed of organopolysiloxane and finely powdered silica, an emulsifier, and water, the emulsion has a volume average particle diameter of 6 μm or more and 18 μm or less, and the particles within this particle size range have a volume An emulsion type silicone antifoaming agent characterized by a distribution ratio of 40% or more.