JPH02131105A - Defoaming agent for coating material - Google Patents

Abstract

PURPOSE:To restrain foaming inorganic solvents by preparing defoaming agents for coating material using, as a main component, organopolysiloxane containing a specific quantity of three different kinds of organosiloxane units represented by certain general formulas. CONSTITUTION:A defoaming agent for coating material is prepared, comprising 20-70mole% of organosiloxane unit represented by the formula I (R<f>: a 1-14C perfluoroalkyl group, R<1>: a 1-8C bivalent hydrocarbon group, R<2>: a 1-8C monovalent hydrocarbon group, a: 1<=a<=3, b: 0<=b<=2, wherein a+b: 1<=a+b<=3), 0.2-10mole% of organosiloxane unit represented by the formula II (R<3>: H, lower alkyl group, etc., R<4>: a 2-6C bivalent hydrocarbon group, R<5>: a 1-6C bivalent hydrocarbon group), and 79.8-20mole% of organosiloxane unit represented by the formula III (R<7>: a 1-8C monovalent hydrocarbon group).

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is useful as an antifoaming agent for paints, particularly for defoaming foaming in organic solvent-based solutions such as paints. This invention relates to an antifoaming agent for paints that does not cause repellency such as fish eyes.

(Prior art) Silicone antifoaming agents exhibit an excellent antifoaming effect when added in trace amounts of 10 to 200 ppm.They have excellent heat resistance and chemical resistance, and are chemically inert, so they foam even under adverse conditions. It has excellent properties such as being stable without reacting with substances, being safe when added to the food manufacturing process as it is non-toxic under the Food Sanitation Law, and safe when used in wastewater treatment. Because of this, it is widely used in various industrial processes that involve foaming. For this purpose, silicone oils such as dimethylpolysiloxane, methylphenylpolysiloxane, and methylvinylpolysiloxane are mixed with finely powdered silica to form an oil compound. The silicone oil compound is used in the form of an emulsion, or an emulsion made by dispersing this silicone oil compound in water with a surfactant.

However, although these silicone-based antifoaming agents exhibit excellent antifoaming effects against aqueous foaming, they have lower surface tension than aqueous foaming agents, and are less effective against foaming from organic solvents in which silicone has greater solubility. This has the disadvantage that the foaming effect becomes inferior. Therefore, as an antifoaming agent for organic solvent systems, a method has been proposed in which a composition consisting of dimethylpolysiloxane and siloxane resin is used to suppress foaming when processing petroleum residues into oil coke. (See Japanese Unexamined Patent Publication No. 53-98306) However, this antifoaming effect is not satisfactory. A method using perfluoroalkyl group-containing siloxane, which is poorly soluble in organic solvents, has also been proposed (see Japanese Patent Publication No. 35-12564), but this method has problems with solubility and dispersibility in solvents. Moreover, when added to paints, etc., repellents such as pinholes and fish eyes occur, making it difficult to obtain a good coating film.

(Structure of the Invention) The present invention relates to an antifoaming agent for paints that solves the above-mentioned disadvantages.
Co> i: Rfb is a perfluoroalkyl group having 1 to 14 carbon atoms, R1 is a divalent hydrocarbon group having 1 to 8 carbon atoms, R2 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, a is a positive integer where 1≦a≦3, b is O≦b≦2, and a plus is 1≦a+b≦3)
20 to 70 mol% of organosiloxane units represented by
2) General formula % formula % (R4 is a hydrogen atom, a lower alkyl group or an acyl group, Rs
is a divalent hydrocarbon group having 2 to 6 carbon atoms, and Rs is a divalent hydrocarbon group having 1 to 8 carbon atoms.
R6 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, Ω is an integer of 1 or more, m and n are each O or 1, C is 1≦C≦3, d is O≦d≦2,
c+d is a positive integer satisfying 1≦c+d≦3) 0.2 to 10 mol% of organosiloxane units, 3) general formula substituted or substituted monovalent hydrocarbon group, e is 1.2 or 3) Siloxane unit 79.8-20 mol%
The main ingredient is an organopolysiloxane consisting of the following.

That is, as a result of various studies on the development of antifoaming agents for paints that exhibit excellent antifoaming effects against foaming caused by organic solvents, the present inventors found that the conventionally used general formula R75iO! L
i, R7 is unsubstituted or substituted 1 having 1 to 8 carbon atoms;
When an organopolysiloxane consisting of an organosiloxane unit having a valence hydrocarbon group with a of 1.2 or 3 contains an organosiloxane unit containing a perfluoroalkyl group, the surface tension and solubility of the organosiloxane in an organic solvent are Therefore, it has an excellent effect on suppressing foaming in organic solvent systems, but when used as a paint additive, it causes repellency that causes pinholes, fish eyes, etc. in the paint, so it is further When an ether group-containing organosiloxane unit is included, the surface tension and solubility in organic solvents are well balanced, and it exhibits excellent physical properties as an antifoaming agent for paints, and when used as a paint additive. We have also discovered that the paint does not suffer from repellency, and we have developed the types of perfluoroalkyl group-containing organosiloxane units and polyether group-containing organosiloxane units used for this N.
The present invention was completed by conducting research on the amount of compounding and other factors.

Below, the organopolysiloxane used in the antifoaming agent for paints of the present invention will be explained in detail.

The organopolysiloxane used in the antifoaming agent for paints of the present invention is composed of the three types of organosiloxane units described above.

The perfluoroalkyl group-containing organosiloxane unit constituting this organopolysiloxane is represented by a general formula, where R is a perfluoropropyl group, perfluorobutyl group, perfluorohexyl group, perfluorooctyl group, perfluorodecyl group, etc. A linear or branched perfluoroalkyl group having 1 to 14 carbon atoms, and R1 is a divalent hydrocarbon group having 1 to 8 carbon atoms, such as a methylene group, ethylene group, propylene group, phenylene group, etc. , R2 is an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a cycloalkyl group such as a cyclohexyl 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 phenylethyl group. or a non-carbon number of 1 to 8 selected from aralkyl groups, such as chloromethyl groups, cyanoethyl groups, etc. in which some or all of the hydrogen atoms bonded to the carbon atoms of these groups are substituted with halogen atoms, cyano groups, etc. Substituted or substituted same or different monovalent hydrocarbon groups, a is 1≦a≦3, b
It is assumed that 0≦b≦2 and a+b is a positive integer of 1≦a+b≦3. This organosiloxane unit is CH.

For example, if the content is less than 20 mol% of this perfluoroalkyl group-containing organosiloxane unit in the organopolysiloxane, the surface tension of the organopolysiloxane will not be sufficiently lowered, and it will not dissolve in the organic solvent. The foaming effect becomes insufficient due to the increase in foaming properties.
If it exceeds 70 mol%, dispersibility in organic solvents and expandability into foam will deteriorate, resulting in insufficient defoaming effect, especially foam-breaking ability, and quick-acting properties, so the content should be in the range of 20 to 70 mol%. is required.

The polyether group-containing organosiloxane unit constituting this organopolysiloxane is represented by a general formula, where R3 is a hydrogen atom, a lower alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, an acetyl group, or a propionyl group. acyl group, R4 is a divalent hydrocarbon group having 2 to 6 carbon atoms such as ethylene group, propylene group, isobutylene group, etc., R5 is exemplified by methylene group, ethylene group, propylene group, phenylene group, etc. A divalent hydrocarbon group having 1 to 8 carbon atoms, R6 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms similar to R2 described above,
Q is an integer greater than or equal to 1, m and n are each 0 or 1, C is 1≦C≦3, d is 0≦d≦2, and c+d is 1≦c + d
It is assumed to be a positive integer with ≦3.

This polyether group-containing organosiloxane unit is CH.

CH3 ■ CH.

■ CH.

For example, if the content of this polyether group-containing organosiloxane unit in the organopolysiloxane is 0.2 mol% or less, the anti-repellency effect of the paint when this silicone antifoaming agent is added to the paint system is reduced. If it is 10 mol % or more, the solubility of this organopolysiloxane in organic solvents will become too large and the antifoaming effect in organic solvent systems will decrease.
It needs to be in the range of 0 mol%.

Next, the organosiloxane unit constituting this organopolysiloxane is represented by the general formula % formula % (3), where R7 has the same number of carbon atoms as R2 described above.
8 unsubstituted or substituted identical or different monovalent hydrocarbon groups, e being 1.2 or 3; Examples of this include methylsiloxane group, phenylsiloxane group, vinylsiloxane group, trimethylsiloxane group, dimethylsiloxane group, methylphenylsiloxane group, dimethylphenylsiloxane group, dimethylvinylsiloxane group, methylvinylsiloxane group, etc. The content of organosiloxane units in the organopolysiloxane is the remaining amount of the total amount of the two organosiloxane units described above, so it may be 79.8 to 20 mol%.

The organopolysiloxane used as the antifoaming agent for paints of the present invention contains three types of organosiloxane units represented by the above formulas (1), (2), and (3) in the above content range. However, this organopolysiloxane is, for example, an organosiloxane represented by the formula % (where Rf, R1, and R2 are the same as above), and the formula (HR7S i O)9 and the formula (R72S iO) (where p , q, r are numbers from 3 to 5) in a predetermined ratio, equilibration reaction is performed in the presence of an acid, and then =-S
It can be obtained by subjecting the H group to an addition reaction of a polyether represented by the formula % (7) (where R3 and R4 are as described above) in the presence of a platinum catalyst. Examples include:

-S i (CH,)3 -CH2CH2C8F1□ The antifoaming agent for paints of the present invention containing the organopolysiloxane thus obtained as a main ingredient exhibits an excellent foam suppression effect against organic solvent-based foaming. In particular, even when added to oil-based paint systems such as polyarylate-based and polyurethane-based paints, it does not cause repellency to the paint. When adding this substance to an organic solvent system, it may be added as it is in N, or it may be added to a ketone solvent such as methyl ethyl ketone or methyl isopluketone or 1,1,2-trifluoro-1,2,2-trichloroethane. It may be used by dissolving it in a halogen-containing organic solvent. Note that it is optional to add fillers such as antioxidants and fumed silicone to this organopolysiloxane depending on its use.

Next, synthesis examples and examples of the organopolysiloxane used as the antifoaming agent for paints of the present invention will be given.

Synthesis Example 1 Hexamethyldisiloxane 17.4 g, 1,3°5-
671.4 g of tristrifluoropropyl-1,3,5-trimethylcyclotrisiloxane, 1,246.5 g of octamethylcyclotetrasiloxane and 1,3,
5.7-Titramethylcyclotetrasiloxane 64.7
20 g of concentrated sulfuric acid was added thereto and reacted at room temperature for 8 hours.

40 g of water was added and stirred at room temperature for 4 hours, then 40 g of sodium hydrogen carbonate was added to neutralize the acid, and the acid was filtered.
-1) 1,900g was obtained.

Next, to 11,000 g of Siloxane A-1, 970 g of polyether represented by the formula, 1.000 g of toluene, and an isopropyl alcohol solution of chloroplatinic acid (platinum concentration 2
% by weight) was added, and the reflux temperature (115-118
℃) for 8 hours, and then heated to 120℃ under a reduced pressure of 10 mmHg.
1.830 g (abbreviated as -'1) was obtained.

Synthesis Example 2 8.4 g of hexamethyldisiloxane, 1,578.0 g of 1,3,5-trisnonafluorohexyl-1,3,5-trimethylcyclotrisiloxane, 382.6 g of octamethylcyclotetrasiloxane, and 1, 3, 5
．． 7-titramethylcyclotetrasiloxane 31.0g
were mixed and treated in the same manner as in Synthesis Example 1 below.
-2) 1,950 g was obtained.

Next, 438.3 g of polyether represented by the formula and 1.000 g of toluene were added to 21,000 g of this siloxane A-2.
g and 2.0 g of isopropyl alcohol solution of chloroplatinic acid (platinum concentration 2% by weight) were added and treated in the same manner as in Synthesis Example 1.
-2) 1,338 g was obtained.

Synthesis Example 3 11.8 g of hexamethyldisiloxane, 1,587.8 g of 1,3°5-tristrifluoropropyl-1,3,5-trimethylcyclotrisiloxane, 315.8 g of octamethylcyclotetrasiloxane and 1, 3,5
,7-titramethylcyclotetrasiloxane 43.7
g was mixed and treated in the same manner as in Synthesis Example 1, resulting in an organopolysiloxane (hereinafter siloxane A
-3) 1,950 g was obtained.

Next, to 31,000 g of this siloxane A-163.6 g of polyether represented by the formula %) and 1.0 g of toluene were added.
000 g and 2.0 g of an isopropyl alcohol solution of chloroplatinic acid (platinum concentration 2% by weight) were added and treated in the same manner as in Synthesis Example 1, resulting in an organopolysiloxane represented by the formula (hereinafter abbreviated as siloxane B-3). 1,082
g was obtained.

Synthesis Example 4 7.1 g of hexamethyldisiloxane, 1,357.6 g of 1,3,5-dostrifluoropropyl-1,3,5-trimethylcyclotrisiloxane, 630.1 g of octamethylcyclotetrasiloxane and 1, 3,5.
When 5.2 g of 7-titramethylcyclotetrasiloxane was mixed and treated in the same manner as in Synthesis Example 1, organopolysiloxane represented by the formula (hereinafter siloxane A) was obtained.
-4) 1,950 g was obtained.

Next, 252.4 g of polyether represented by the formula and 1.000 g of toluene were added to 41,000 g of this siloxane A-4.
g and 2.0 g of isopropyl alcohol solution of chloroplatinic acid (platinum concentration 2% by weight) were added and treated in the same manner as in Synthesis Example 1.
-4) 1,164.7 g was obtained.

Synthesis Example 5 5.5 g of hexamethyldisiloxane, 1,709.3 g of 1,3,5-trishebutadefluorodecyl-1,3,5-trimethylcyclotrisiloxane, 244.6 g of octamethylcyclotetrasiloxane and 1,3 ,5
．． 7-titramethylcyclotetrasiloxane 40.6
g was mixed and treated in the same manner as in Synthesis Example 1, resulting in an organopolysiloxane represented by formula 1 (hereinafter siloxane A).
-5) 1,950 g was obtained.

Next, 567.5 g of polyether represented by the formula and 1.000 g of toluene were added to 51,000 g of this siloxane A-5.
and 2.0 g of isopropyl alcohol solution of chloroplatinic acid (platinum concentration 2% by weight) were added and treated in the same manner as in Synthesis Example 1.
1,457.8 g (abbreviated as -5) was obtained.

Synthesis Example 6 12.9 g of hexamethyldisiloxane, 1,221.9 g of 1,3゜5-tristrifluoropropyl-1,3,5-trimethylcyclotrisiloxane, 574.5 g of octamethylcyclotetrasiloxane and 1, 3,5
．． 7-Titramethylcyclotetrasiloxane 190.7
g was mixed and treated in the same manner as in Synthesis Example 1.
Organopolysiloxane (hereinafter referred to as siloxane A) represented by the formula
-6) 1,950 g was obtained.

Next, to 61,000 g of this siloxane A-2, 2,856 g of polyether represented by the formula and 2.000 g of toluene were added.
g and 2.0 g of isopropyl alcohol solution of chloroplatinic acid (platinum concentration 2% by weight) were added and treated in the same manner as in Synthesis Example 1.
-6) 3,586.0 g was obtained.

Synthesis Example 7 3.5 g of hexamethyldisiloxane, 680.6 g of 1,3.5-tristrifluoropropyl-1,3,5-trimethylcyclotrisiloxane and 315.9 g of octamethylcyclotetrasiloxane were mixed. After adding 10 g of concentrated sulfuric acid and reacting at room temperature for 8 hours, adding 20 g of water and stirring at room temperature for 4 hours, then adding 20 g of sodium hydrogen carbonate to neutralize the acid and filtering, the formula 950 g of organopolysiloxane (hereinafter abbreviated as siloxane B-7) represented by the formula was obtained.

Examples 1 to 5, Comparative Examples 1 to 2 100 g of light oil and 1 g of siloxane B-1 to B-7 obtained in Synthesis Examples 1 to 7 described above in a 1Q measuring cylinder.
1 minute, 3 minutes, 5 minutes, 10 minutes, 15 minutes when these are placed in a glass foaming tube and aerated at a speed of IQZ minutes.
When the amount of foaming was measured after 20 minutes, the results shown in Table 1 were obtained, and siloxanes B-1 to B-5 and B-
7 showed excellent antifoaming properties, but siloxane B-6 showed excellent antifoaming properties.
It scaled over in 6 seconds.

Next, siloxanes B-1 to B-7 obtained in Synthesis Examples 1 to 7 described above were added to 100 g of a 50% toluene solution of an acrylic resin.
After adding 0.2 g and stirring well, this was used to screen print on vinyl coated paper, and after drying, the number of repellents on each 5c + e square area of this printed surface was measured, and the results are also listed in Table 1. The same results were obtained, and siloxanes B-1 to B-6 all showed excellent repellency prevention effects when the number of repellents was O or less than 3, but siloxane B-7 showed poor results at 150 to 200 repellents. showed that.

Chapter 1 Table Procedural amendment list voluntary) December 14, 1988 Yoshi, Commissioner of the Japan Patent Office 1) Takeshi Moon 2゜ 3゜ name of invention Antifoaming agent for paint person who makes corrections Relationship to the case Patent applicant Name (206) Shin-Etsu Chemical Co., Ltd. 4゜

Claims (1)

[Claims] 1,1) General formula (R^fR^1)_aR^2_bSiO
[_4_-_(_a_+_b_)]_/[_2] (here, R^f is a perfluoroalkyl group having 1 to 14 carbon atoms,
R^1 is a divalent hydrocarbon group having 1 to 8 carbon atoms, R^2 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and a is 1≦
Organosiloxane unit 20-
70 mol%, 2) General formula ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (Here, R^3 is a hydrogen atom, lower alkyl group, or acyl group, and R^4 is a divalent hydrocarbon having 2 to 6 carbon atoms. Base, R^5
is a divalent hydrocarbon group having 1 to 8 carbon atoms, and R^6 is a divalent hydrocarbon group having 1 to 8 carbon atoms.
8 unsubstituted or substituted monovalent hydrocarbon groups, l is an integer of 1 or more, m and n are each 0 or 1, c is 1≦c≦3, d
0≦d≦2, and c+d is a positive integer such that 1≦0+d≦3) 0.2 to 10 mol% of organosiloxane units 3) General formula R^7_eSiO[4-e]/[2]( Here, R^7 is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and e is 79.8 to 20 mol% of organosiloxane units represented by 1, 2, or 3). An antifoaming agent for paints characterized by containing siloxane as a main ingredient.