JPH11244609A - Defoaming agent composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a defoaming agent which has excellent defoaming property and improves the water resistance of the product by using a defoaming compsn. comprising a compd. expressed by a specified formula. SOLUTION: This defoaming agent compsn. consists of a compd. expressed by the formula. In the formula, R1 represents a hydrogen atom or a 1-18C alkyl group and different alkyl groups may be included in the molecule, (p) is 1 to 4 and a combination of different numbers may be allowed in the molecule. The total of the carbon atoms which constitute (R1)p is 8 to 45. R2 represents a 1-2C alkyl group and a combination of different alkylene groups may be included in the molecule. AO represents a 2-4C oxyalkylene group and a combination of different groups may be included in the molecule. (n) is the average repetition number satisfying 0<=n<=3, (a) is 0 or a positive number and a combination of different numbers may be included in the molecule. The total of (a) is >=n+2 and <=4×(n+2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an antifoaming agent.
More specifically, it exhibits excellent defoaming properties against bubbles generated in various processes in the paint and coating industries including the pulp and paper industry, building industry, dyeing industry, synthetic resin manufacturing industry, ink industry, etc. The present invention relates to a novel antifoaming composition having a small decrease.

[0002]

2. Description of the Related Art Conventionally, for these industrial uses, polyether-based end products having no adverse effects such as oil spots, pinholes, repelling, and oil floating on the final product, and almost no generation of scum and sediment are observed. Foams are preferred.

Conventionally, polyether-based antifoaming agents include:
Alcohols or polyhydric alcohols having 2 to 8 valences, such as stearyl alcohol, dipropylene glycol, glycerin, sorbitan, sucrose, etc., to which an alkylene oxide has been added, or those having their terminals esterified with fatty acids (Japanese Patent Publication No. 45-30189). No., Tokiko 47-40
394, JP-B-49-38923, JP-A-50-2
2788, JP-A-54-133484, JP-A-54-134484
-135298, JP-B-61-7847, JP-A-Hei 2
JP-A-21905 and JP-A-2-21907), dihexylphenol added with an alkylene oxide (JP-A-55-92110), and alkylphenol added with an alkylene oxide (JP-B-47-32511). ) And propylene glycol fatty acid monoester (JP-A-52-97385).

[0004]

In general, polyether-based antifoaming agents have a drawback that the antifoaming property and the water resistance of the final product using the antifoaming agent in the production process are not compatible.
Those obtained by adding an alkylene oxide to a monovalent to octahydric alcohol or the above-mentioned alkylene oxide adducts of dihexylphenol and alkylphenol have insufficient water resistance, and propylene glycol fatty acid monoester has a relatively small decrease in water resistance. However, there was a disadvantage that the defoaming property was inferior. Accordingly, an object of the present invention is to provide an antifoaming agent having excellent defoaming properties and improved water resistance.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a compound having a specific structure satisfies both the defoaming property and the water resistance, and have reached the present invention.
That is, the present invention relates to the following general formula (I)

Embedded image [In the formula, R1 represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and may be a combination of different ones in the molecule.
p is 1 to 4, and may be a different number of combinations in the molecule. The total number of carbon atoms constituting (R1) p is 8 to
45. R2 represents an alkylene group having 1 to 2 carbon atoms, and may be a combination of different alkylene groups in the molecule. AO
Represents an oxyalkylene group having 2 to 4 carbon atoms, and may be a combination of different oxyalkylene groups in the molecule. N indicates the average number of repetitions, where 0 ≦ n ≦ 3. a is 0 or a positive number, and may be a combination of different numbers in the molecule. The sum of a is not less than n + 2 and not more than 4 × (n + 2). ] It is a defoaming agent composition which consists of a compound represented by these.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a compound having the structure of the general formula (I) can be obtained by addition polymerization of a condensate of a phenol and an aldehyde with an alkylene oxide, or addition polymerization of a phenol with an alkylene oxide. It is also possible to obtain by condensing with aldehydes after the reaction, and it is not limited to any of them.

In the present invention, phenols include phenol and monoalkylphenols having 1 to 18 carbon atoms, dialkylphenols and trialkylphenols. Among these, preferred are butylphenol, octylphenol, nonylphenol, dodecylphenol, dibutylphenol and the like. These can be used alone or as phenols.
Used as a mixture of products. Also, the compound of the present invention,
The total number of carbon atoms of the alkyl group represented by R1 in the general formula (I) is from 8 to 45, preferably from 10 to 43. If it is less than 8, water resistance and defoaming properties are not sufficient, and if it exceeds 45, sufficient defoaming properties cannot be obtained.

In the present invention, aldehydes include formalin, paraformaldehyde, acetaldehyde, methylal, trioxane and the like. Among these, preferred are formalin and paraformaldehyde.

In the present invention, the condensation reaction between the phenol or the addition polymer of the phenol and the alkylene oxide and the aldehyde is carried out in the presence of an acid or alkali catalyst. As the acidic catalyst, mineral acids such as hydrochloric acid, nitric acid, sulfuric acid, perchloric acid and phosphoric acid, organic acids such as oxalic acid, formic acid, acetic acid and p-toluenesulfonic acid and metal salts thereof are known. Known alkaline catalysts include alkali metal hydroxides such as sodium hydroxide, and amines such as ammonia, dimethylamine and hexamethylenetetramine. Of these, acidic catalysts are preferred, and hydrochloric acid, oxalic acid and zinc acetate are particularly preferred.

In the present invention, the condensation reaction is carried out in the presence of water and / or an organic solvent using the above catalyst in the range of 40 to 100.
It is obtained by reacting at 30 ° C. for about 30 minutes to 5 hours.
The molecular weight (Mn-GPC) of the obtained compound was determined by a GPC method (number average molecular weight, molecular weight standard substance: polystyrene). The acid value (or hydroxyl value) was measured, and the number average molecular weight per hydroxyl group (Mn-OH, this value was 56
100 divided by the acid value). The average degree of polymerization (n + 2, the average content of benzene rings) is (Mn-GP
C) / (Mn-OH). The average degree of polymerization of the compound in the present invention is from 2 to 5, preferably from 2.5 to
4.5. If it is less than 2, satisfactory defoaming properties cannot be obtained. If it exceeds 5, the final compound becomes too viscous to handle.

In the present invention, the compound imparting an oxyalkylene group having 2 to 4 carbon atoms includes, for example, ethylene oxide (hereinafter abbreviated as EO), propylene oxide (hereinafter abbreviated as EO).
PO), isobutylene oxide, 1,2-butylene oxide, tetrahydrofuran and the like.
Of these, EO and PO are preferred.

In the present invention, the addition polymerization reaction of the alkylene oxide is carried out in a vessel capable of withstanding pressure, controlling the temperature, and stirring, so that 0.05 to 2.0% by weight of potassium hydroxide with respect to the weight of the compound at the end of the polymerization. The reaction is carried out under ordinary conditions using an alkali metal hydroxide such as cesium hydroxide as a catalyst. For example, the temperature is 70 to 150 ° C, preferably 90 to 130.
° C, the maximum pressure (gauge pressure) during the reaction is 8 kg / cm ² ,
Preferably, it is 6 kg / cm ² , and the time required for the reaction is 4-1.
It takes about 2 hours.

In the present invention, the average number of moles of the alkylene oxide added is 1 to 4, preferably 1.5 to 3.5 per hydroxyl group. If it is less than 1, no dispersibility in water can be obtained, and if it exceeds 4, the water resistance decreases. The proportion of EO in the total alkylene oxide added to the hydroxyl group is 35% or less, preferably 30% or less in terms of molar ratio. If it exceeds 35%, the water resistance decreases. The order of addition polymerization to the hydroxyl group is not particularly limited, and the addition form may be either block or random.

In the present invention, as a method for removing the catalyst after the alkylene oxide addition polymerization reaction, for example, a method in which an alkaline catalyst is neutralized with an acidic component, and a generated salt is removed by filtration (Japanese Patent Publication No. 47-3745). A method using an alkali adsorbent (JP-A-53-123499),
A method of dissolving in a solvent and washing with water (Japanese Patent Publication No. 49-14359)
Japanese Patent Application Laid-Open No. SHO 51-1979, a method using an ion exchange resin
No. 23211), a method of neutralizing an alkaline catalyst with carbon dioxide gas and filtering the generated carbonate (Japanese Patent Publication No. 52-33).
No. 000) and a method of neutralization with various organic acids and inorganic acids, and any of them may be used or used in combination.

The antifoaming composition of the present invention may be added in the form of a solution previously diluted to an appropriate concentration with water and / or an organic solvent, or may be added as it is. The addition amount is usually 0.1 to 5,000 ppm, preferably 1 to 1,000 ppm, based on the foaming aqueous solution.

[0016]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. The results of the defoaming test and the water resistance test are shown in Tables 1 to 5. In addition, the part in an Example, a test method, etc. means a weight part.

[Defoaming Test Method 1] 500 ml of foaming test water (newspaper paper white water) was placed in a glass foam tube, and 3
Adjust the temperature to 5 ° C. Then, while circulating the test water from the bottom of the foaming tube at a rate of 3000 ml / min using a pump, the test water is foamed by dropping it on the surface of the test liquid approximately 20 cm below the foaming tube upper portion (the height is set to be constant). . When the foam height reached 100 mm, the defoamer 2PPM (vs. test water) was added, and the time required for the foam surface to decrease the most (seconds, the smaller the foam, the better the dispersibility) The foam height (Mm, smaller means better initial foam breaking) and foam height after 5 minutes of continuous circulation (mm, smaller means better foam suppression) to evaluate and compare defoaming properties did. The evaluation results are shown in Table 1.

[Water resistance test method 1] Stighit sizing test (J) using paper obtained under the following test paper preparation conditions
(IS P8122), and the water resistance was evaluated and compared with the average value (in seconds, the higher the value, the better the water resistance). The evaluation results are shown in Table 1. [Test paper preparation conditions] Apparatus: Kumagaya Riki Kogyo Co., Ltd. square sheet machine Basis weight: 50 g / m ² Chemicals used: Pulp (DIP / GP / NBKP / LBKP = 60/30/5/5) [100] Part] Rosin sizing agent [1 part] Sulfuric acid band [3 parts] Defoamer composition [0.5 part]

[Defoaming Test Method 2] A test solution (dyed liquid) having the following composition was prepared, and defoaming properties were evaluated and compared in the same manner as in Defoaming Test Method 1. However, the addition amount of the defoamer was 5 PPM, and the temperature control was 40 ° C. The evaluation results are shown in Table 2. [Test solution composition] Chemicals used: Karayas Supra Black B-160 [2 parts] Dianix Orange B-SE manufactured by Nippon Kayaku Co., Ltd. [2 parts] Acetic acid (80% product) manufactured by Mitsubishi Kasei Corporation [0. 3 parts] anhydrous sodium sulfate [25 parts] water [970.7 parts]

[Water resistance test method 2] After dyeing a polyester cloth under the following conditions, reduction washing is performed. Next, a wet friction fastness test after drying (JIS L0849-1971)
And the water resistance was evaluated and compared. (Evaluation was made in 5 stages, 5 was the best) The evaluation results are shown in Table 2. [Dyeing conditions] Dye: Dyanic thread G-SE (4% owf) Defoamer: [0.2 parts] (1000 parts for dye bath) PH: Acetic acid (80% product) Temperature and time: 130 ° C x 45 minutes [Reduction washing conditions] Temperature and time: 80 ° C. × 10 minutes (bath ratio 1:20) Post-treatment: Wash and dry

[Defoaming test method 3] A slurry having the following composition was prepared, and the solid content per square centimeter was 1.0 with a filter.
g of a slate plate was prepared. The filtration step is performed under reduced pressure (40
cmHg) The operation was performed at a slurry temperature of 25 ° C., and the end point of the filtration was a point in time when the surface of the slate plate had no water. The time required for this filtration end point (filtration time) and the water content of the papermaking slate plate were measured, and the defoaming properties were evaluated and compared. Moisture content (%)
Was calculated by (moisture weight / solid content weight) × 100. The smaller the filtration time and the water content, the better the defoaming property. The evaluation results are shown in Table 3. [Slurry composition] Solid content: Portland cement [100 parts] N-UKP pulp [6 parts] Rock wool fiber [3 parts] Water: An amount that gives a solid content of 7% by weight is added. However, use the water after repeating the slurry preparation / filtration eight times. Defoaming agent: Immediately before the defoaming test, add 100 PPM to the solid content and stir with a mixer for 10 seconds.

[Water resistance test method 3] After the above-mentioned defoaming test, one drop of water was dropped on the surface of the dried and fired slate plate.
The time until complete immersion was measured and the water resistance was evaluated and compared. The higher the value, the better the water resistance. The evaluation results are shown in Table 3.

[Defoaming Test 4] The vinyl chloride slurry (solids concentration: 28.5%) obtained by the suspension polymerization method was used for 20
0 cc was taken in a 1000 ml measuring cylinder, 100 ppm of antifoaming agent (based on solid content) was added, and then immersed in a hot water bath controlled at 60 ° C. 1000c nitrogen from 1000ml measuring cylinder bottom with glass ball filter G-4
The volume of the foam was measured at regular intervals by aeration at c / min. After stopping the ventilation, the volume of the foamed resin (floating resin) was measured. The smaller the numerical values, the better the defoaming property. The evaluation results are shown in Table 4.

[Water Resistance Test Method 4] A resin is blended in the following ratio, and roll kneading is performed at 150 ° C. for 5 minutes. Next, after press molding at 180 ° C., the weight change rate in immersion in boiling water for 10 hours was measured according to ISK5400. The smaller the value, the better the water resistance. The evaluation results are shown in Table 4. [Resin composition] Vinyl chloride (PVC): 100 parts Plasticizer (phthalic acid): 50 parts Heat stabilizer (tin): 5 parts Antifoaming agent (vs. PVC): 100 ppm

[Defoaming test method 5] JP-A-60-158
In accordance with the method described in Japanese Patent Application Publication No. 259, an aqueous coating composition having the following composition (made uniform with a disper mill) was prepared, and a diluted coating composition of paint / water = 4/1 (weight ratio) was applied to the disper mill. Air bubbles forcibly (4000 rpm x 3 m
After in), the defoaming properties were compared and evaluated by density measurement. The density obtained from the sample subjected to the defoaming treatment was set to a reference value of 1.00, and the density of the test sample was indicated by a relative comparison value. The closer to 1.00, the better the defoaming property. Also, make a coating film about 2mm thick on a glass plate,
The coating film surface after drying was visually evaluated. The evaluation was ◎ (there is almost no bubble or crater on the coating film surface, and there is gloss).
(There were many bubbles and craters on the coating film surface, and there was no gloss). The evaluation results are shown in Table 5.

[Test aqueous coating composition] Acrylic polymer dispersion (50% by weight water) 524 parts Propylene glycol 74 parts Sodium polyacrylate 2 parts Titanium dioxide 250 parts Carbon black 12 parts Aqueous ammonium polyacrylate solution (98% by weight) 81 Part Preservative 8 parts 2,2,4-trimethylpentane-1,2-diol-diisobutyrate 17 parts Water 30 parts Antifoam 2 parts

[Water Resistance Test Method 5] A glass tube having an inner diameter of 1.5 cm and a height of about 5 cm was set up on the surface of the coating film obtained in the above test, and sealed so as not to leak water. Ion-exchanged water was charged and left at room temperature for 24 hours. Then, after removing the glass tube and gently wiping off the water on the coating film surface, one hour later, the color of the test coating film surface was evaluated by comparing with the system without the defoamer. ◎ indicates that the color has hardly changed, x indicates that the color has changed to whitish, ◎, ○,
It was evaluated as a four-point scale of Δ and ×. The evaluation results are shown in Table 5.

Synthesis Example 1 300 ml of 3 equipped with a reflux condenser, a thermometer and a stirrer
Butyl phenol (hereinafter, C ₄ -Ph)
50 ml of a mixed solvent (hereinafter abbreviated as solvent) of the same volume of 0.40 mol (60.0 g) water and isopropanol,
37% aqueous solution of formalin (hereinafter abbreviated as F-37)
31 mol (26.1 g) and 0.3 g of oxalic acid (dihydrate, the same applies hereinafter) were charged and heated to reflux while stirring on a hot water bath for 2 hours. Further, 0.3 g of oxalic acid was added, and the mixture was heated under reflux with stirring for 1 hour. Then, 80 ml of water was added to cool the reaction system. The resin phase was precipitated by standing, and the aqueous phase was removed. Then, it was dried at 120 ° C. under reduced pressure. The condensate obtained is called base A. The molecular weight of the base A by GPC analysis was 660, the acid value was 334, and the average degree of polymerization was 3.
Nine.

[0029] 3-neck flask of the same 300ml Synthesis Example 2 Synthesis Example 1, C ₄ -
Ph 0.2 mol (30.0 g) 0.1 mol (20.6 g) of octylphenol (hereinafter abbreviated as C ₈ -Ph), 50 ml of solvent, 0.21 mol (17.8 g) of F-37 and oxalic acid 0 Then, the mixture was heated to reflux while stirring on a hot water bath for 2 hours. Further, 0.2 g of oxalic acid was added, and the mixture was heated and refluxed with stirring for 1 hour. Then, the reaction system was cooled by adding 80 ml of water, and then treated in the same manner as in Synthesis Example 1. The condensate obtained is called base B. According to GPC analysis of Base B, the molecular weight was 515, the acid value was 312, and the average degree of polymerization was 2.9.

Synthesis Example 3 In the same 300 ml three-necked flask as in Synthesis Example 1, 0.25 mol (65.5 g) of dodecylphenol (hereinafter abbreviated as C ₁₂ -Ph), 50 ml of a solvent, and 0.3 ml of F-37 were added. 15 mol (12.6 g) and 0.15 g of oxalic acid were charged,
The mixture was heated to reflux while stirring on a water bath for 2 hours. Further, 0.15 g of oxalic acid was added, and the mixture was heated and refluxed with stirring for 1 hour. Then, the reaction system was cooled by adding 80 ml of water, and then treated in the same manner as in Synthesis Example 1. The condensate obtained is called base C. According to GPC analysis of Base C, the molecular weight was 660, the acid value was 210, and the average degree of polymerization was 2.5.

The three-neck flask of the same 300ml as in Comparative Synthesis Example 1 Synthesis Example 1, C ₄ -
Ph0.6 mol (90.0 g) 70 ml of solvent, F-37
0.55 mol (46.2 g) and 0.4 g of oxalic acid
And heated to reflux while stirring on a hot water bath for 2 hours. Further, 0.4 g of oxalic acid was added, and the mixture was heated under reflux with stirring for 1 hour. Then, 100 ml of water was added to cool the reaction system, followed by the same treatment as in Synthesis Example 1. The condensate obtained is called base D. GPC analysis of Base D revealed that the molecular weight was 953, the acid value was 342, and the average degree of polymerization was 5.8.

Example 1 A 200-ml pressure-resistant reactor equipped with a temperature controller, a pressure gauge, and a stirrer was charged with 0.1 mol (66.0 g) of base A and 0.2 g of potassium hydroxide (special grade reagent, the same applies hereinafter). 130
The mixture was stirred for 1 hour under reduced pressure at ℃ to dehydrate. Then 100 ° C
The stirring was continued for about 5 hours while gradually introducing 1.0 mol (58.0 g) of PO into the reaction system. When the pressure (gauge pressure) of the reaction system became 0 kg / cm ² or less, the temperature was raised to 130 ° C., and stirring was continued for about 2 hours while gradually introducing 0.2 mol (8.8 g) of EO into the reaction system. Was. After the pressure of the reaction system reached an equilibrium, it was cooled to 80 ° C. Then a temperature controller,
The polymerization reaction product is taken in a 300 ml glass beaker equipped with a stirrer. At 80 ° C., 4.0 g of water (about 3.0% based on the polymerization reaction product, the same applies hereinafter) was added, and the mixture was stirred for about 30 minutes. Next, KYOWARD 600 (Kyowa Chemical Co., Ltd.) 8.2 g
(About 6.0% based on the polymerization reaction product, the same applies hereinafter) and 9
Stirred at 0 ° C. for 1 hour. Then, it was filtered and dehydrated under reduced pressure using No. 2 filter paper (manufactured by Toyo Roshi Kaisha, Ltd.) to obtain a colorless to pale yellow transparent liquid. The obtained compound was used for convenience (Base A
/ P10 / E2). The viscosity is 1,2 at 25 ° C.
It was 40 mPa · s. This was subjected to a defoaming test and a water resistance test.

Example 2 In the same manner as in Example 1, (base A / P6 / E1.5) was obtained. The viscosity was 1,470 mPa · s at 25 ° C. This was subjected to a defoaming test and a water resistance test.

Example 3 A (base A / P15) was obtained in the same manner as in Example 1. The viscosity was 1,080 mPa · s at 25 ° C. This was subjected to a defoaming test and a water resistance test.

Example 4 First, 1 mol of EO and then 9 mol of PO were added to base B in the same manner as in Example 1 to obtain (base B / E1 / P9).
I got The viscosity at 25 ° C. was 1,120 mPa · s. This was subjected to a defoaming test and a water resistance test.

Example 5 In the same manner as in Example 1, 2 moles of EO and PO7
Mole of the mixed alkylene oxide was added at 100 ° C. to give (base C / E2, P7). The viscosity was 1,050 mPa · s at 25 ° C. This was subjected to a defoaming test and a water resistance test.

Comparative Example 1 An antifoaming test and a water resistance test were carried out without adding an antifoaming agent.

Comparative Example 2 First, 8 mol of PO and then 2 mol of EO were added to C ₁₂ -Ph in the same manner as in Example 1 to obtain (C ₁₂ -Ph / P8 / E2)
I got The viscosity was 740 mPa · s at 25 ° C.
This was subjected to a defoaming test and a water resistance test.

Comparative Example 3 In the same manner as in Example 1, first, 4 moles of PO and then 4 moles of EO were added to the base A to obtain (base A / P4 / E4). The viscosity was 1,320 mPa · s at 25 ° C.
This was subjected to a defoaming test and a water resistance test.

Comparative Example 4 In the same manner as in Example 1, 15 mol of PO was added to Base C to obtain (Base C / P15). Viscosity 9 at 25 ° C
It was 20 mPa · s. This was subjected to a defoaming test and a water resistance test.

Comparative Example 5 In the same manner as in Example 1, first, 15 mol of PO and then 6 mol of EO were added to the base D, and (base D / P15 / E6)
I got The viscosity was 3,920 mPa · s at 25 ° C. This was subjected to a defoaming test and a water resistance test.

COMPARATIVE EXAMPLE 6 First, PO was added to stearyl alcohol in the same manner as in Example 1.
10 moles and then 8 moles of EO were added. Next, esterification was performed with oleic acid to obtain (steryl alcohol / P10 / E8 / oleic acid) having an esterification rate of 95%. The viscosity was 1,220 mPa · s at 25 ° C.
This was subjected to a defoaming test and a water resistance test.

[0043]

Embedded image

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

[Table 4]

[0048]

[Table 5]

[0049]

The defoamer composition according to the present invention can be used in industries dealing with various foaming aqueous solutions, such as the paper pulp industry, the building industry,
In the dyeing industry, the synthetic resin manufacturing industry, the paint industry including the ink industry, and the coating industry, etc., the defoaming property is greatly improved compared to conventional polyether-based defoamers.
Operation stability and the like can be improved by adding a small amount. Further, since the decrease in water resistance of the final product can be suppressed, it is also useful for improving the quality.

Claims (9)

[Claims] 1. A compound represented by the following general formula (I) [In the formula, R1 represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms, and may be a combination of different ones in the molecule.
p is 1 to 4, and may be a different number of combinations in the molecule. The total number of carbon atoms constituting (R1) p is 8 to
45. R2 represents an alkylene group having 1 to 2 carbon atoms, and may be a combination of different alkylene groups in the molecule. AO
Represents an oxyalkylene group having 2 to 4 carbon atoms, and may be a combination of different oxyalkylene groups in the molecule. N indicates the average number of repetitions, where 0 ≦ n ≦ 3. a is 0 or a positive number, and may be a combination of different numbers in the molecule. The sum of a is not less than n + 2 and not more than 4 × (n + 2). ] The defoaming agent composition which consists of a compound represented by these. 2. The antifoaming composition according to claim 1, wherein R1 in the general formula (I) is an alkyl group having 3 to 12 carbon atoms. 3. The antifoaming composition according to claim 1, wherein the molar ratio of oxyethylene groups in the AO of the general formula (I) is 35% or less. 4. The antifoaming composition according to claim 1, which is an antifoaming agent for a paper pulp production process. 5. The antifoaming composition according to claim 1, which is an antifoaming agent for a hydraulic inorganic plate production process. 6. The antifoaming composition according to claim 1, which is an antifoaming agent for a dyeing step. 7. The antifoaming composition according to claim 1, which is an antifoaming agent for a synthetic resin production process. 8. An antifoaming agent for a paint production process.
3. The antifoaming composition according to any one of the above items 3. 9. The antifoaming composition according to claim 1, which is a defoaming agent for a coating step.