JPS6134847B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved antifoam composition, and in particular, it aims to provide a paintable antifoam agent containing organopolysiloxane as a main component, which does not cause the "repelling phenomenon" and exhibits a remarkable antifoaming effect. It is something to do. Conventionally, antifoaming agents based on dimethylpolysiloxane have been widely used due to their excellent antifoaming effect, but since dimethylpolysiloxane is essentially a hydrophobic substance, it is not suitable for synthetic resin latex or When applied to emulsions, water-based paints, etc., the resulting coating film will have a sticky eye.
There is a problem of so-called "repelling phenomenon" in which cratering occurs. On the other hand, water-soluble organopolysiloxanes such as polyether-modified siloxanes are hydrophilic and easily dispersed in aqueous systems, so they do not cause repellency and are therefore used in applications where repellency is a problem. (Refer to Publication No. 10188/1983). However, this type of antifoaming agent based on siloxane has a significantly inferior antifoaming effect compared to the conventional emulsion type antifoaming agent based on dimethylpolysiloxane, and is not fully satisfactory as an antifoaming agent. It does not have the performance that it should. In order to solve these problems, attempts have been made to improve the antifoaming effect by adding hydrophobic diorganopolysiloxanes such as dimethylpolysiloxane to polyether-modified siloxanes (Japanese Patent Application Laid-Open No. 1983-1999). (Refer to Publication No. 34854), but when added to latex or water-containing paint,
Since the resin component or organic substance in the system has poor affinity with the diorganopolysiloxane, a repelling phenomenon also occurs, which is disadvantageous in that a significant decrease in commercial value is inevitable. The present invention aims to provide a novel antifoaming composition which eliminates the conventional disadvantages as described above, and which comprises (a) the general formula 100 parts by weight of an oxyalkylene group-containing organopolysiloxane represented by (b) Average composition formula organopolysiloxane represented by
2 to 200 parts by weight and (iii) 0.01 to 60 parts by weight of a silica filler. [In the formula, R ₁ is a monovalent hydrocarbon group, A is a monovalent oxyalkylene group represented by the formula (-R ⁴ )- _g O (-C ₂ H ₄ O〓〓〓R ³ O) _-i Y (Here, Y is a hydrogen atom, a monovalent hydrocarbon group or acyl group having 1 to 10 carbon atoms, R ³ is a divalent hydrocarbon group having 3 to 10 carbon atoms, and R ⁴ is a divalent hydrocarbon group having 2 to 10 carbon atoms. Divalent hydrocarbon group, g is 0 or 1, h is a positive integer of 1 or more, i is 0 or a positive integer, provided that 2≦h+i
≦100, 0.05≦h/h+i≦1.00), D is a divalent oxyalkylene represented by the formula (−R ⁵ O〓〓〓〓C ₂ H ₄ 〓〓〓〓R ⁶ O〓〓〓〓R ⁵ ) − _j group (here R ⁵
and R ⁶ is a divalent hydrocarbon group having 3 to 10 carbon atoms, j is 0 or 1, k is a positive integer of 1 or more,
l is 0 or a positive integer, where 1≦k+l≦
100), ^R2 is a monovalent hydrocarbon group having 8 to 30 carbon atoms, a is 0, 1 or 2, b is a positive integer of 50 or more, e is 0<e<2.4, f is 0<f<
2.4, but 1.8≦e+f≦2.4, 0.02≦f/e+
f≦0.95] Hereinafter, the antifoam composition according to the present invention will be explained in detail. First, the oxyalkylene group-containing organopolysiloxane as component (a) used in the present invention is represented by the above general formula (i), in which R ¹ is a monovalent hydrocarbon group, It preferably represents a monovalent hydrocarbon group having 1 to 30 carbon atoms, including alkyl groups such as methyl, ethyl, propyl, butyl, octyl, tridecyl, and cyclohexyl, phenyl, and tolyl groups. Aryl groups such as vinyl groups, alkenyl groups such as allyl groups, styryl groups or α-methylstyryl groups, and some of the hydrogen atoms bonded to the carbon atoms of these monovalent hydrocarbon groups are halogen atoms, cyano groups, etc. Examples include groups substituted with . Further, A represents _a monovalent oxyalkylene group represented ^by the formula ( ^-R4 ) _-gO ( _{-C2H4O〓〓〓R3O} ) _-iY ...(iii),
Y in this formula is a group selected from a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, or an acyl group, and the monovalent hydrocarbon group includes a methyl group,
Examples include ethyl group, propyl group, butyl group, vinyl group, and phenyl group. Examples of the acyl group include acetyl group and propionyl group. R ³ represents a divalent hydrocarbon group having 3 to 10 carbon atoms, examples of which include propylene group, isopropylene group, butylene group, isobutylene group, and R ⁴ represents a divalent hydrocarbon group having 2 to 10 carbon atoms. It represents a valent hydrocarbon group, and examples thereof include ethylene group, propylene group, isopropylene group, butylene group, and isobutylene group. g, h and i are each as described above. Furthermore, D in the formula (i) is a divalent compound represented by the formula (−R ⁵ O〓〓〓〓C ₂ H ₄ O〓〓〓R ⁶ O〓〓〓〓R ⁵ )− _j ......(iv) represents an oxyalkylene group,
R ⁵ and R ⁶ in this formula represent divalent hydrocarbon groups having 3 to 10 carbon atoms, and examples thereof include the same groups as exemplified for R ³ above. j, k and l are each as described above. Moreover, a, b, c and d in the general formula (i) are each as described above (however, c is preferably 1 to 5). The oxyalkylene group-containing organopolysiloxane represented by the above general formula (i) imparts excellent antifoaming properties and antifoaming durability to the antifoaming agent obtained from the composition of the present invention containing this component (a). From the point of view, ^the ratio of the total number of ethylene oxides ( ^ME ) to the total number of alkylene oxides ( ^M
M ^T (2・a・h+c・k/2・a(h+i)+c
(k+l)) is preferably in the range of 0.05 to 0.80, preferably 0.1 to 0.7, and for the purpose of imparting a good emulsifying and dispersing effect and a repelling effect to the composition of the present invention, , the ratio of the total number of ethylene oxides (M ^E ) to the total number of silicon atoms (M ^S ) in the above general formula (i) M ^E /M ^S
(2・a・h+c・k/b・c+d+2) is 0.05
It is preferable to use one in the range of ~15. The organopolysiloxane containing an oxyalkylene group, which is the component (a), can be synthesized by various methods. A method in which an addition reaction is carried out with hydrogen polysiloxane in the presence of a platinum compound, a method in which a polyether having a hydroxyl group at the end of the molecular chain and an organohydrodiene polysiloxane are subjected to a dehydrohalogenation reaction in the presence of an amine compound, or a molecular chain Examples include a method in which a polyether having a hydroxyl group at the terminal and an organohydrodiene polysiloxane are subjected to a dehydrogenation reaction in the presence of a platinum compound. Specific examples of the polyoxyalkylene group-containing organopolysiloxane represented by the above general formula (i) include the compounds shown below. Next, the component (b) used in the present invention is represented by the average compositional formula (ii) above, which consists of a methyl group that exhibits an antifoaming effect and an organic substance contained in the object to be treated. It is necessary to have at the same time a monovalent hydrocarbon group having a relatively large number of carbon atoms that exhibits affinity for. In the formula, R ² has 8 carbon atoms
-30, preferably 10-30 monovalent hydrocarbon groups, including octyl, tridecyl, α-methylstyryl, and the like. This organopolysiloxane has a methyl group bonded to a silicon atom and a monovalent group having 8 to 3 carbon atoms, from the viewpoint of imparting good antifoaming properties and anti-repellent effects to the antifoaming agent obtained from the composition of the present invention. The ratio between the total amount of hydrocarbon groups (M ⁰ ) and the number of monovalent hydrocarbon groups (M ¹ ) having 8 to 30 carbon atoms bonded to silicon atoms (M ¹ /M ⁰ =f/e+f) is 0.02. ~0.95, preferably 0.05-0.80. In addition, from the viewpoint of workability, the viscosity of this (b) component at 25°C is 50 to 100,000 cS, preferably 100 to 100,000 cS.
It is preferable to use one in the range of 10000cS. This (b) component may be linear, branched, or cyclic as long as it satisfies each of the above conditions, and it may contain monoorganosiloxane units or triorganosiloxane units. You can leave it there. This component (b) can be synthesized by various conventionally known methods, and specifically, it can be synthesized by combining an olefin compound having 8 or more carbon atoms such as octene or α-methylstyrene and methylhydrodiene polysiloxane. A method of addition reaction in the presence of a platinum compound, with a methyl group and 8 carbon atoms in the molecule.
Examples include a method in which cyclosiloxane and dimethylcyclosiloxane having the above-mentioned monovalent hydrocarbon groups at the same time are subjected to an equilibration reaction in the presence of an acidic catalyst such as sulfuric acid or a basic catalyst such as potassium hydroxide. As such organopolysiloxane,
Compounds such as those shown below can be mentioned. From the viewpoint of achieving the object of the present invention, the amount of component (b) to be used is in the range of 2 to 200 parts by weight per 100 parts by weight of component (a). As the silica-based filler as component (c), both wet silica and dry silica conventionally blended in silicone rubber compositions can be used, and specifically, Aerosil (manufactured by Degutsa),
Cab-O-Sil (manufactured by Cabot Co., Ltd.), Carplex (manufactured by Shionogi Co., Ltd.), Tokusil (manufactured by Tokuyama Soda Co., Ltd.),
Nipseal (manufactured by Nippon Silica Co., Ltd.), Ultrasil (C.
P. Examples include those known by trade names such as (manufactured by Hull Corporation), Hi-Sil (manufactured by Pittsburgh Putglas Company), and Santcel (manufactured by Monsanto Chemical Company). This component (c) is based on 100 parts by weight of component (a) above.
It is essential to use it in a range of 0.01 to 60 parts by weight, preferably 0.03 to 20 parts by weight. The antifoam composition according to the present invention can be obtained by uniformly mixing predetermined amounts of the above-mentioned components (a) to (c) using a mixer such as a colloid mill. Conventional emulsifiers, such as polyoxyethylene higher alcohol ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, or polyoxyalkylene glycol and its alkyl ether represented by PPG, may be used in a manner that may impede the purpose of the present invention. There is no problem in using it within the range. The antifoaming composition according to the present invention exhibits an antifoaming effect equivalent to or greater than that of a conventional self-emulsifying antifoaming agent made of a mixed system of dimethylpolysiloxane and hydrophilic polysiloxane at room temperature and high temperature, Moreover, it has an excellent antifoaming effect. Furthermore, when conventional self-emulsifying defoamers are added to water-containing systems such as latex and paints, repellency phenomena such as fish eyes and cratering are observed in the resulting paint films. However, the composition of the present invention has the remarkable effect that such a phenomenon does not occur at all. On the other hand, the composition of the present invention has the same feature as polyether-modified siloxane in that it does not cause the "repelling phenomenon," but in terms of antifoaming effect, it can be used in an amount less than half that of polyether-modified siloxane. Since it shows the same effect, it has the advantage of avoiding disadvantages such as modification of latex due to addition of a large amount. Next, examples of the present invention will be given, and all parts in the examples indicate parts by weight. Example formula Oxyalkylene group-containing methylpolysiloxane represented by the formula Methyl-α-methylstyryl polysiloxane with a viscosity of 1000 cS (25°C) and
An antifoaming agent was prepared by stirring and mixing Nipsil VN ₃ (trade name, finely powdered silica manufactured by Nippon Silica Co., Ltd.) uniformly for 15 minutes (however, the amounts of each component used are as shown in the table). ). Various physical properties of the antifoaming agent thus prepared were investigated and the results are shown in the table below. Antifoaming effect (foaming amount): 100g of anionic styrene-butadiene latex (50% solid weight) and 0.05g of the antifoaming agent prepared above were placed in a measuring cylinder with a capacity of 1000ml, and heated to 80°C. After the temperature was raised, air was continuously introduced at a rate of 500 ml/min through a Dufu user stone, and the amount of foaming was measured after 30 minutes, 1 hour, 2 hours, and 4 hours. Occurrence and extent of fish eyes; After the defoaming test, the latex was taken out onto a clean glass plate, stretched uniformly using a glass rod, and visually examined for the presence and extent of fish eyes.

【table】 Dimethylpolysiloxane shown in was used.

Claims (1)

[Claims] 1 (a) General formula 100 parts by weight of an oxyalkylene group-containing organopolysiloxane represented by (b) Average composition formula organopolysiloxane represented by
An antifoaming agent composition comprising 2 to 200 parts by weight and (iii) 0.01 to 60 parts by weight of a silica filler [wherein R ¹ is a monovalent hydrocarbon group, A is the formula (-R ⁴ ) _-g O( -C ₂ H ₄ O〓〓〓R ³ O) - _i A monovalent oxyalkylene group represented by Y (where Y is a hydrogen atom, a monovalent hydrocarbon group with 1 to 10 carbon atoms or an acyl group, R ³ is a divalent hydrocarbon group having 3 to 10 carbon atoms, R ⁴ is a divalent hydrocarbon group having 2 to 10 carbon atoms, g is 0 or 1, h is a positive integer of 1 or more, i is 0 or Positive integer, provided that 2≦h+i
≦100, ^0.05 ≦h/ _h + _i ^{≦ 1.00} ) _; Oxyalkylene group (here
R ⁵ and R ⁶ are divalent hydrocarbon groups having 3 to 10 carbon atoms, j is 0 or 1, k is a positive integer of 1 or more, l is 0 or a positive integer, provided that 1≦k+l
≦100), ^R2 is a monovalent hydrocarbon group with 8 to 30 carbon atoms, a is 0, 1 or 2, b is a positive integer of 50 or less, c is a positive integer of 1 or more, d is Positive integer, e is 0<e<2.4, f is 0<f<2.4, but 1.8≦e+f≦2.4, 0.02≦f/e+f≦
0.95〕