JPH0442042B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an antifoam composition containing a hydrophobic base oil and a hydrophobically treated fine silica powder as main ingredients. [Prior art and its problems to be solved] Conventionally, silicone antifoaming agents have been mainly composed of organopolysiloxane oil and untreated fine silica powder, and have been used in combination with alcohol-based, ester-based, mineral oil, vegetable oil,
Compared to non-silicone antifoaming agents such as synthetic oils,
Because it exhibits an excellent antifoaming effect with a small amount of addition,
It is widely used for foam breaking and foam suppression in drainage, dyeing, fermentation, latex, cement, paint, adhesive, petroleum industries, etc. However, such silicone antifoaming agents have no antifoaming effect in systems that are vigorously agitated, such as in aeration tanks at wastewater treatment plants, jet dyeing, or under alkaline liquids, such as in the pulp cooking process in the pulp and paper industry. There was a drawback that the durability was significantly reduced, and it was necessary to add an antifoaming agent continuously or intermittently. However, since this is extremely uneconomical, there has been a desire in the industry for an antifoaming agent with excellent long-lasting antifoaming effects. Examples of antifoaming agents that overcome these drawbacks include (1)
Silica fine powder hydrophobically treated with dimethyldichlorosilane is dispersed in organopolysiloxane oil (see Japanese Patent Publication No. 1983-31836), (2) Silica fine powder hydrophobically treated with a nitrogen-containing organosilicon compound. (3) An intimate mixture of dimethylpolysiloxane raw rubber, untreated fine silica powder, and polydimethylsiloxane hydroxide dispersed in organopolysiloxane oil (see Japanese Patent Publication No. 1983-35556). (Refer to Japanese Patent Publication No. 7691/1986), (4) Fine silica powder obtained by baking commercially available silicone oil at high temperature and dispersed in organopolysiloxane oil (Japanese Patent Publication No. 1983-1999)
(Refer to Publication No. 24309). However, the above antifoaming agents (1) and (2) have a drawback in that their antifoaming performance is lower, especially for alkaline liquids, compared to neutral liquids. The antifoaming agent (3) has the disadvantage of low antifoaming performance because the fine silica powder is compressed when dimethylpolysiloxane raw rubber and fine silica powder are mixed, and the antifoaming agent (4) has the following disadvantage: 250～
There is a disadvantage that it is very expensive to bake the silicone oil at a high temperature of 300°C, and in addition, the hydrophobicity of the silica in the antifoaming agents (3) and (4) is not sufficient. In addition to these drawbacks, the above (1) to (4)
Both antifoaming agents also have the disadvantage that the sustainability of the antifoaming effect is not always fully satisfactory. [Problems to be Solved by the Invention] As a result of intensive research aimed at solving the drawbacks of the prior art, the present inventors have arrived at the present invention. An object of the present invention is to provide an antifoaming composition that has an excellent antifoaming effect and its persistence, especially in systems that are vigorously stirred or in alkaline liquids. [Means for Solving Problems and Effects] The object of the present invention described above is to: (A) 100 parts by weight of a hydrophobic base oil selected from an organopolysiloxane oil, an organic oil, and a mixed oil of an organopolysiloxane oil and an organic oil; (B) General formula (In the formula, R is a monovalent hydrocarbon group, n is an integer of 1 to 15, Q is a halogen atom, a hydroxyl group, or -OR ¹
silica fine powder having a specific surface area of at least 50 m ² /g, which has been hydrophobically treated with a diorganosiloxane oligomer represented by R ¹ is a monovalent hydrocarbon group. This is accomplished by a foam composition. The hydrophobic base oil used as component (A) in the present invention is selected from organopolysiloxane oils, organic oils, and mixed oils thereof. A typical example of this organopolysiloxane oil has an average unit formula R ² aSiO _4-a/2 (wherein R ² is a monovalent dihydrogen group and has 7 carbon atoms)
The following are preferred, examples include methyl group, ethyl group, propyl group, butyl group, and phenyl group, a
is 1.9 to 2.1. ) and is liquid at room temperature. Dimethylpolysiloxane oil, methylphenylpolysiloxane oil, methylethylpolysiloxane oil, methyloctylpolysiloxane oil,
Ethylphenylpolysiloxane oil is exemplified, but methylalkylpolysiloxane oil, particularly dimethylpolysiloxane oil, is preferred from the standpoint of antifoaming effect and economic efficiency. The terminal end of the organopolysiloxane oil may be either a triorganosilyl group or a hydroxyl group. The viscosity should be liquid at room temperature, but from the viewpoint of antifoaming effect and workability, the viscosity at 25℃ should be 50~50℃.
Preferably it is in the range of 10,000 centistokes. Examples of the organic oil include aliphatic hydrocarbon oil, aromatic hydrocarbon oil, alicyclic hydrocarbon oil, and vegetable oil, and those having a viscosity similar to that of the organopolysiloxane oil mentioned above are used. When a mixed oil of an organopolysiloxane oil and an organic oil is used, the mixing ratio is not particularly limited and is arbitrary, and includes the case where a small amount of one of the oils is added to the other. Examples of the fine silica powder for component (B) used in the present invention include fumed silica, silica aerogel, precipitated silica, fine quartz powder, fine fused silica powder, and fine calcined silica powder. The surface area should be at least 50 m ² /g.
Component (B) consists of these silica fine powders with the general formula (wherein R, n and Q are as described above).
It is formed by hydrophobic treatment using a diorganosiloxane oligomer represented by: Examples of the monovalent hydrocarbon group as R include those similar to ^R2 . The R's in the same molecule may be the same or different, but generally one of the side chains is a methyl group. Examples of the monovalent hydrocarbon group as R ¹ include those similar to those for R ² , but lower alkyl groups and alkoxyalkyl groups are preferred. n is 1~
is an integer of 15. If n is 0, the antifoaming effect will be poor in sustainability, and if n is 16 or more, the proportion of the functional group Q in the oligomer will decrease, making it difficult to make the silica fine powder hydrophobic. be. It is thought that the functional group Q of this diorganosiloxane oligomer undergoes a condensation reaction with the ≡Si--OH group on the silica fine powder, bonds to the silica surface, and alienates the silica fine powder. In order to hydrophobicize the silica fine powder with this diorganosiloxane oligomer, it can be carried out according to the usual manufacturing method of hydrophobic treated silica filler.For example, the diorganosiloxane oligomer is added while stirring the silica fine powder. The method used is to mix until homogeneous and then heat.
Alternatively, the diorganosiloxane oligomer may be added to the fine silica powder while stirring it under heating. A preferred heating temperature is in the range of 100 to 200°C. This is because if the temperature is less than 100°C, the condensation reaction between the fine silica powder and the oligomer will be difficult to complete, and if the temperature exceeds 200°C, it is uneconomical. The amount of the diorganosiloxane oligomer added to the fine silica powder is not particularly limited because it varies depending on the number of ≡Si-OH groups in the fine silica powder and the proportion of Q in the oligomer, but usually 100% of the fine silica powder is added. It is used in a range of 1 to 50 parts by weight. The silica fine powder becomes highly hydrophobic due to the diorganopolysiloxane oligomer, and this is thought to provide the above-described antifoaming effect and its sustainability. The antifoam composition of the present invention contains 100% of the above-described component (A).
It can be obtained by mixing 2 to 50 parts by weight of component (B). When mixing, 120 to 200
It is desirable to heat and stir at ℃ for 2 to 3 hours.
The mixing device is preferably a device that can heat and stir at the same time, and in order to make the composition fine or homogeneous, homomixer, ball mill,
It may be processed using a colloid mill, three rolls, etc. If necessary, an inert gas such as nitrogen may be used during mixing. In short, any device can be used as long as it can mix uniformly. The antifoam composition of the present invention can be used in various forms depending on the type of foaming system. For example, when the foaming system is oil-based or solvent-based, it can be diluted with an organic solvent before use. The organic solvents referred to here include conventionally known hydrocarbon solvents that are liquids with a boiling point of 250°C or less, halogenated hydrocarbons, amines, alcohols, ethers, ketones, esters,
Selected from acids, etc. For example, methylcyclohexane, xylene, petroleum naphtha, perchlorethylene, promochloroethane, dichlorobutane, triethylamine, butylamine, tributylamine, isopropyl alcohol, butyl alcohol, amyl alcohol, hexyl ether, butyl cellosolve, dioxane, methyl ethyl ketone, diethyl ketone, methyl butyl ketone , ethyl acetate, cellosolve acetate, ethyl propionate, acetic acid, propionic acid, and 2-ethylhexoeic acid, but are not limited to these. Furthermore, when the foaming system is aqueous, the composition of the present invention can be emulsified using a conventionally known surfactant and water and used as an emulsion type. The surfactants mentioned here include, for example, sorbitan fatty acid ester, glycerin fatty acid ester,
Examples include, but are not limited to, propylene glycol fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene castor oil, ethylene oxide and propylene oxide adducts. do not have. Additionally, protective colloids may be used during emulsification, such as methylcellulose, lactose, sodium alginate, sucrose fatty acid ester, gum tragacanth, polyvinyl alcohol, hydroxypropylcellulose, carboxyvinyl polymer, etc. However, it is not limited to these. Furthermore, the antifoam composition of the present invention can also be used as a powder antifoam agent. The antifoam composition of the present invention includes the above-mentioned organic solvents,
In addition to water, surfactants, and protective colloids, organosilanes, organosilazane, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, finely powdered metal oxides, scaly fillers, aminoorganofunctional silicon compounds, A pigment or the like may be added. In the antifoam composition of the present invention, the hydrophobic group and the hydrophobically treated fine silica powder form an intimate mixture, so that the fine silica powder is not liberated from various foaming liquids. Whether it is used as is or in the form of an emulsion, its defoaming effect is far superior to that of conventional products.
The antifoaming effect does not deteriorate in alkaline foaming liquids, which is the case with conventional silicone antifoaming agents. [Example] Next, Examples and Comparative Examples of the present invention will be shown. In Examples and Comparative Examples, parts mean parts by weight, and viscosity is a value measured at 25°C. Note that the unit of viscosity, cs, is an abbreviation for centistoke. Example 1 Low-boiling components were removed from a hydrolyzate obtained by adding a small amount of water to dimethyldichlorosilane, and the structural formula A dimethylsiloxane oligomer represented by the formula (where n is a mixture of 2 to 5) was obtained. Fumed silica with a specific surface area of 200m ² /g
100 g was placed in a 5-separable flask, 20 g of the above dimethylsiloxane oligomer was added dropwise, and the mixture was mixed for 1 hour. Next, the temperature of this product was raised to 200°C, and nitrogen gas was passed while stirring until the reaction by-products were removed, to obtain a hydrophobic silica fine powder. 10 parts of this hydrophobic silica and dimethylpolysiloxane oil (viscosity:
100 parts of 1000cs) were mixed for 30 minutes at room temperature in a Hobart mixer, and then mixed for 2 hours at 150°C using a mixer equipped with a stirrer and a heating device to prepare an antifoaming agent composition. Example 2 Low boiling point components were removed from a mixture obtained by hydrolyzing dimethyldichlorosilane with a large amount of water, and the structural formula A dimethylsiloxane oligomer represented by the formula (where n is a mixture of 3 to 12) was obtained. 100 g of fumed silica fine powder with a specific surface area of 250 m ² /g was placed in a separable flask.
20 g of the above dimethylsiloisane oligomer was added dropwise and mixed for 1 hour. Then this one is 150
The mixture was heated to 0.degree. C. and mixed for 3 hours to obtain a hydrophobic silica fine powder. 6 parts of this hydrophobic silica fine powder and 100 parts of dimethylpolysiloxane oil (viscosity 50 cs) blocked at both ends with trimethylsiloxy groups were mixed in the same manner as in Example 1 to prepare an antifoam composition. Example 3 Low-boiling components were removed from a mixture obtained by adding a small amount of water to methylphenyldiethoxysilane and hydrolyzing it, and the structural formula was A methylphenylsiloxane oligomer represented by the formula (where n is a mixture of 3 to 10) was obtained. Fine precipitated silica powder with a specific surface area of 170 m ² /g
100 g was placed in a 5-separable flask, 30 g of the above methylphenylsiloxane oligomer was added dropwise, and the mixture was mixed for 1 hour. Then this one is 150
The temperature was raised to 0.degree. C., and nitrogen gas was passed while stirring until the reaction by-products were removed to obtain hydrophobic silica fine powder. 10 parts of this hydrophobic silica and dimethylpolysiloxane oil (viscosity:
500cs) and 70 parts paraffin oil (viscosity 50cs at 40°C)
30 parts were mixed in the same manner as in Example 1 to prepare an antifoam composition. Example 4 9 parts of the hydrophobic silica of Example 2 and castor oil (viscosity
700cs) in the same manner as in Example 1 to prepare an antifoam composition. Comparative Example 1 100 parts of dimethylpolysiloxane oil (viscosity 1000cs) blocked at both ends with trimethylsiloxy groups and 8 parts of Aerosil R972 (fine silica powder hydrophobically treated with dimethyldichlorosilane) manufactured by Degutsusa of West Germany were mixed in the same manner as in Example 1. A defoamer composition was prepared by mixing. Comparative Example 2 100 parts of dimethylpolysiloxane oil (viscosity 500 cs) blocked at both ends with trimethylsiloxy groups and 8 parts of Taranox (fine silica powder treated with a nitrogen-containing organosilicon compound) manufactured by Talco, Inc. in the United States were mixed in the same manner as in Example 1. A defoamer composition was prepared by mixing. Comparative Example 3 Fumed silica with a specific surface area of 200 m ² /g
100g was placed in a 5 separable flask, and 20g of dimethylpolysiloxane oil (viscosity 100cs) blocked at both ends with trimethylsiloxy groups was added dropwise and mixed well.
Baking treatment was performed by heating at 300°C for 2 hours. 10 parts of this hydrophobically treated silica and dimethylpolysiloxane oil (viscosity:
1000cs) were mixed in the same manner as in Example 1 to prepare an antifoam composition. Comparative Example 4 100 parts of dimethylpolysiloxane crude rubber endblocked with vinyl dimethylsiloxane groups at both ends, 75 parts of silica fine powder having a specific surface area of approximately 255 m ² /g, and dimethylsiloxane oligomer endblocked at both ends with silanol groups (mixture of polymerization degree of 7 to 12) 22 Mix 1 part and add approx.
The mixture was kneaded at 175°C for 3 hours. 10 parts of this mixture and 100 parts of dimethylpolysiloxane oil (viscosity 500 cs) endblocked with trimethylsiloxane groups at both ends were mixed in the same manner as in Example 1 to prepare an antifoam composition. The following defoaming effect test was conducted on each of the defoaming agent compositions of Examples 1 to 4 and Comparative Examples 1 to 4, and
The results are shown in Table 1. <Duration test of defoaming effect> 1.0% by weight aqueous solution of surfactant Octapol 100 (polyoxyethylene octyl phenyl ether) manufactured by Sanyo Chemical Industries, Ltd. in a 300ml glass bottle with a lid.
ml was taken and used as a neutral foaming liquid. Separately, 0.40 g of the antifoam composition was accurately weighed into a 100 ml volumetric flask, and tertiary butanol was added thereto to make 100 ml. 1.0 ml of this antifoam solution was collected with a pipette and added to the foaming solution. This was set in a shaker and shaken for 10 seconds to forcibly foam, and then the time until the foam disappeared was measured. Repeat this operation and
When it takes more than 5 minutes for the foam to disappear,
The number of repetitions up to that point (excluding those requiring 5 minutes or more) was tentatively referred to as the duration, and was used to represent the durability of the defoaming effect. In addition, a foaming solution having a pH of 13 by dropping a 50% aqueous sodium hydroxide solution into the neutral foaming solution described above was similarly tested to determine the number of times it lasted.

[Table] Examples 5 to 8 20 parts of the antifoam composition of Example 1 and Kao Atlas Co., Ltd.
After mixing 3 parts of the surfactant Span 60 (sorbitan fatty acid ester), 2 parts of Atomul P40S (glycerin fatty acid ester) and 75 parts of water at 60 to 70°C for 20 minutes, the mixture was treated with a homomixer to form an emulsion. This was referred to as Example 5. Example 6 was prepared by emulsifying the antifoam composition of Example 2 under the same conditions as Example 5. Example 7 was prepared by emulsifying the antifoam composition of Example 3 under the same conditions as Example 5. Example 8 was prepared by emulsifying the antifoam composition of Example 4 under the same conditions as Example 5. Comparative Examples 5 to 7 Comparative Example 5 was prepared by emulsifying the antifoaming compound of Comparative Example 1 under the same conditions as Example 5. Comparative Example 6 was prepared by emulsifying the antifoaming compound of Comparative Example 2 under the same conditions as in Example 5. Comparative Example 7 was obtained by emulsifying the antifoaming compound of Comparative Example 3 under the same conditions as Example 5. The antifoaming emulsions of Examples 5 to 8 and Comparative Examples 5 to 7 were subjected to the following antifoaming test, and the results are shown in Table 2. <Defoaming test> A 1.0% by weight aqueous solution of surfactant Octapol 100 (polyoxyethylene octyl phenyl ether) manufactured by Sanyo Chemical Industries, Ltd. was placed in a graduated cylinder.
200 ml of KOH prepared to pH 11 and 0.10 g of antifoam emulsion were taken, air was blown at 600 ml/min through a glass ball filter, and the time (minutes) until the total foam volume reached 800 ml was measured.

【table】

[Table] Tables 1 and 2 show that the antifoam composition according to the present invention has excellent antifoaming effect and durability in neutral and alkaline liquids. [Effects of the Invention] The antifoam composition of the present invention (iii) contains at least 50 m 2 of at least 50 m ² which has been hydrophobically treated with 100 parts by weight of a hydrophobic base oil such as an organopolysiloxane oil and a diorganosiloxane oligomer having halogen atoms or the like at both ends. /g
Since the main ingredient is 2 to 50 parts by weight of fine silica powder having a specific surface area of

Claims (1)

[Scope of Claims] 1 (A) 100 parts by weight of a hydrophobic base oil selected from organopolysiloxane oils, organic oils, and mixed oils of organopolysiloxane oils and organic oils, and (B) general formula (In the formula, R is a monovalent hydrocarbon group, n is an integer of 1 to 15, Q is a halogen atom, a hydroxyl group, or -OR ¹
The main ingredient is 2 to 50 parts by weight of fine silica powder having a specific surface area of at least 50 m ² /g, which has been hydrophobically treated with a diorganosiloxane oligomer represented by R ¹ is a monovalent hydrocarbon group. Antifoam composition.