WO2021203556A1 - Organosilicon composite emulsion defoamer for papermaking industry, and preparation method therefor - Google Patents

Abstract

The present invention provides an organosilicon composite emulsion defoamer for papermaking industry, and a preparation method therefor. First, a polyvinyl ester polymer is introduced, so as to improve the foam breaking and defoaming performance, in particular, to enhance the defoaming effect in a long-chain foaming medium by means of specific molecular weight design, and to implement stabilization and protection functions for an emulsion. Second, polyether modified silicone oils having different HLB values, i.e., a high HLB value, an intermediate HLB value, and a low HLB value, are introduced as emulsifiers, the polyether modified silicone oil having a structure similar to that of a silicone paste, being not prone to be separated from a silicone grease, and greatly improving the storage stability and defoaming durability of the emulsion, and in addition, polyether modified organosilicon introduced having very low surface tension near a cloud point thereof and also having a good defoaming function. The defoamer is prepared by using a method of emulsification at room temperature, the preparation process is simple, energy-saving, and convenient for industrial production, and the resulting defoamer has high defoaming efficiency, good defoaming durability, and good product dilution stability and storage stability.

Description

Organosilicon composite emulsion type defoamer for papermaking industry and preparation method thereof Technical field

The invention relates to a defoamer for the papermaking industry which is a fine chemical additive. Therefore, the present invention belongs to the technical field of fine chemicals.

Background technique

In most industrial production processes, a large number of bubbles will cause trouble, such as affecting production efficiency, causing equipment damage, or even making production impossible in severe cases. For example, in the pulping process of the papermaking process, natural substances such as fatty acids, resin acids, and lignin contained in the pulping raw materials react with the added caustic soda, alkali sulfide and other chemicals to generate fatty acid soaps, resin acid soaps, and other foams. Substances, especially pine, after cooking, due to the high content of saponified turpentine oil, the foaming is particularly strong, and the raw material contains high molecular substances such as cellulose, which has a foam stabilizing effect, and the generation of foam is not conducive to the alkali recovery of black liquor. The defoaming method used in the paper industry generally adopts the chemical defoaming method. The defoaming agent is added to the foaming system for defoaming and foam suppression, which can reduce the air content in the slurry, improve the cleaning effect, and increase the slurry hanging in the cage Thickness, thereby improving production efficiency. Existing defoamers include fatty acids and their derivatives, polyethers, silicones, etc. Among them, silicone defoamers are chemically inert, physiologically inert, pollution-free, good defoaming performance, heat, cold, weather and The characteristics of outstanding aging performance, flexibility and lubricating performance have been in-depth research.

The invention patent CN201711127498.8 discloses a defoamer composition for papermaking and a preparation method thereof, which is composed of dimethyl silicone oil, polymethylsiloxane, ethyl vinyl ether, emulsifier (anionic surfactant, Polyoxyethylene polyol ether), dispersant (hard core soft shell polymer microspheres), surfactant (sodium dodecyl sulfonate). The invention cited core-shell polymerized polymers, but did not highlight the effects and effects of their additions. The invention uses more ionic surfactants, which will bring negative effects on foaming, usually simple and unmodified two The durability of methyl silicone oil and polymethyl siloxane in inhibiting foam is not good. Patent CN106868935A discloses a defoamer for papermaking and a preparation method thereof. The defoamer for papermaking includes: modified dimethylsiloxane, modified polyoxyethylene ether, silicon dioxide, emulsifier, non-ionic surface active Agent, thickener. The defoamer for papermaking is prepared by simple stirring. The paper-making defoamer prepared by the invention introduces modified polyoxyethylene ether, which improves the dispersion of dimethylsiloxane and the spreadability of the defoamer to a certain extent. However, the amount of silica in the defoaming agent is large, and only simple mixing is used. A large amount of silica is difficult to form a good dispersion in dimethylsiloxane and modified polyoxyethylene ether, and the product The stability and uniformity of it are difficult to guarantee. Moreover, once the silica peels and settles in the defoaming agent, the defoaming effect is difficult to last.

In the present invention, the silicone paste of relatively high viscosity silicone defoaming composition is used as the main defoaming and foam suppressing unit with its low surface tension and difficult to solubilize, and polyvinyl ester polymer is used as the auxiliary defoaming unit. , Its unique molecular structure design has good foam breaking and low foam stability characteristics for resin acids, fatty acids, lignin and other foaming media with long carbon chain polybenzene ring structure. The emulsifier used in the present invention is a polyether modified silicone oil with a three-dimensional structure, which is designed and prepared into an emulsifier with high, medium and low cloud points and different HLB values by using the HLB theory. Temperature series and fatty alcohol polyoxyethylene ether series are better. Through proper HLB value adjustment, the low surface tension chemical energy of lamellar liquid crystal is formed in the emulsification process under suitable HLB, which can be emulsified at room temperature

Summary of the invention

The invention discloses an organosilicon composite emulsion type defoamer for the papermaking industry and a preparation method thereof. Firstly, a polyvinyl ester polymer prepared by designing a branched molecular structure is introduced, and the interaction between polar and non-polar groups is introduced. With the combination, it can effectively destroy the stability of the foam liquid wall, improve the foam breaking and defoaming performance, especially the specific molecular weight design improves its defoaming effect in the long-chain foaming medium. Polyvinyl ester prepared by solution polymerization The selected solvent for solution polymerization is polyether with defoaming effect, which has a stable and protective effect on the emulsion; secondly, polyether-modified silicone oil with different HLB values of high, medium and low is introduced as an emulsifier. Siloxane provides a cross-linked and branched spatial network structure. Its structure is close to that of silicone paste. It has better combination and is not easy to detach from the silicone grease. This greatly improves the storage stability and defoaming durability of the emulsion. At the same time, it is introduced The polyether-modified silicone has very low surface tension near its cloud point and also has a good defoaming effect. Compared with conventional emulsifiers, it has stronger emulsification efficiency and lower foaming ability. It is more suitable to be used as an emulsifier of defoamer; finally, the defoamer is prepared by emulsification at room temperature. The preparation process is simple, energy-saving, and convenient for industrial production. The final defoamer obtained has high defoaming efficiency and good defoaming durability. , And the product has good dilution stability and storage stability.

Detailed ways

The organic silicon composite emulsion type defoamer for the paper industry of the present invention is composed of the following components:

A. Silicone paste

The silicone paste of the present invention is made of hydrogen-containing silicone oil, hydroxy silicone oil, hydrophobic white carbon black, and silicone resin under the action of a catalyst. This component accounts for 10% to 26% of the total mass of the defoamer.

B. Polyvinyl ester polymer

The polyvinyl ester polymer in the present invention is designed by molecular structure, and acrylic ester monomers and allyl polyether monomers are prepared into polyvinyl esters by solution radical polymerization. The molecular weight of ester polymers is 5000-100000.

This component accounts for 5% to 15% of the total mass of the defoamer.

C. Polyether modified silicone oil emulsifier

The polyether-modified silicone oil in the present invention is prepared from hydrogen-containing silicone oil, vinyl-containing polyether, and diethylene-terminated polydimethylsiloxane through hydrosilylation reaction. The structural formula is as follows

Wherein, R is a hydrogen atom, a methyl group; subscripts x, y, z, p are the degree of polymerization of the siloxy link, x is an integer from 1 to 50, y is an integer from 20 to 500, and z is from 1 to 4 , P is an integer from 200 to 500; subscripts n and m are respectively the degree of polymerization of ethylene oxide and propylene oxide, n is an integer from 1 to 25, and m is an integer from 0 to 5; subscript q is -CH _{The degree of polymerization of 2} is an integer of 1-3. By adjusting the values of n, m, x, y, p, z, polyether modified silicone oils with different cloud points and HLB values can be obtained, and this component accounts for 3% to 5% of the total mass of the defoamer.

Component C polyether modified silicone oil emulsifier is divided into three parts: C1, C2 and C3, in which the HLB value of C1 is 2-5, the HLB value of C2 is 6-8, and the HLB value of C3 is 9-20; The HLB value of emulsifier C formed by C1, C2 and C3 is in the range of 8.5-10.5. Component C is used in two parts. The amount of component C in the first part accounts for 70-90% of the total mass of component C. The amount of the second part component C accounts for 10-30% of the total mass of component C;

D, thickening water

The thickening water of the present invention is prepared by water and a thickening agent, wherein the thickening agent is selected from xanthan gum, guar gum, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, polyacrylic acid , Polyacrylamide and polyacrylate, preferably polyacrylate. The water is deionized water. The mass concentration of the thickening water is 1% to 4%; the amount of thickening agent accounts for 15% to 23% of the total mass of the defoamer. The two parts of thickening water, D1 and D2, account for 1/4 and 3/4 of the total mass of thickening water, respectively.

E. Water

The water in the present invention is deionized water, and the amount is 35%-50% of the total mass of the defoamer. Water is divided into two parts, E1 and E2, each accounting for one-half of the total water mass.

The preparation method of a composite emulsion type defoamer for the paper industry of the present invention is as follows:

(1) The first part of component C polyether modified silicone oil emulsifier and thickening water D1 are mixed uniformly to form a viscous high-concentration emulsified paste M;

(2) The second part of the component C polyether modified silicone oil emulsifier and the component B polyvinyl ester polymer are mixed uniformly to obtain a mixture N;

(3) Turn on the high-speed disperser and slowly add the component A silicone paste to M at a low speed of 300-500r/min, then slowly add the mixture N, and slowly increase the speed to 1000-1200r/min;

(4) Slowly add water E1 until the emulsion is completely turned to O/W state, increase the speed to 1500-1800r/min. Keep the speed for 5min-10min, slowly add the remaining water E2, and keep the speed for 10min-20min;

(5) Reduce the rotating speed to 300-500r/min, add the remaining thickening water D2, and stir evenly to obtain the defoamer of the present invention.

Examples of polyether modified silicone oil

Examples of component C1 are as follows;

Examples of component C2 are as follows;

Examples of component C3 are as follows:

Example of silicone paste

Silicon Paste Example A1-Example A5:

Refer to the preparation of Example 1 to Example 5 in patent CN103275493B

Examples of emulsion defoamers:

Example 1.

(1) 35 parts of polyether modified silicone oil emulsifier (the mass ratio of C1-1, C2-1, C3-3 is C1-1: C2-1: C3-1 = 1:9:60) and 57.5 parts increase Thick water (polyacrylate with a mass concentration of 1%) is mixed uniformly to obtain a viscous high-concentration emulsified cream M1;

(2) 15 parts of polyether modified silicone oil emulsifier (the mass ratio of C1-1, C2-1, C3-3 is C1-1: C2-1: C3-1=1: 9:60) and 100 parts of poly Vinyl lipid polymer (molecular weight 5000) is mixed uniformly to obtain mixture N1

(3) Turn on the high-speed machine to disperse at a low speed of 300r/min, slowly add 120 parts of silicone paste A1 to M1, and then slowly add the mixture N1; after mixing, slowly increase the speed to 1000r/min for stirring;

(4) Slowly add 250 parts of water until the emulsion is completely turned to O/W state, increase the speed to 1500r/min, and keep the speed for 5 minutes. Slowly add the remaining 250 parts of water. Maintain the speed for 10 minutes;

(5) Reduce the rotating speed to 300r/min, add 172.5 parts of thickening water and stir evenly to obtain the defoamer of the present invention.

Example 2

(1) 36 parts of polyether modified silicone oil emulsifier (the mass ratio of C1-2, C2-1, C3-2 is C1-2: C2-1: C3-2 = 9:12:11) and 37.5 parts increase Thick water (methyl cellulose with a mass concentration of 4%) is mixed evenly to obtain a viscous high-concentration emulsified cream M2;

(2) 4 parts of polyether modified silicone oil emulsifier (the mass ratio of C1-2, C2-1, C3-2 is C1-2: C2-1: C3-2 = 9:12:11) and 150 parts of poly The vinyl lipid polymer (molecular weight is 100,000) is evenly mixed to obtain the mixture N2;

(3) Turn on the high-speed machine to disperse at a low speed of 500r/min, slowly add 220 parts of silicone paste A22 to M2, and then slowly add the mixture N2; after mixing, slowly increase the speed to 1200r/min for stirring;

(4) Slowly add 220 parts of water until the emulsion is completely turned to O/W state, increase the speed to 1800r/min, and keep the speed for 10 minutes. Slowly add the remaining 220 parts of water and keep the rotation speed for 20 minutes;

(5) Reduce the rotating speed to 500r/min, add 112.5 parts of thickening water and stir evenly to obtain the defoamer of the present invention.

Example 3

(1) 40 parts of polyether modified silicone oil emulsifier (the mass ratio of C1-3, C2-2, and C3-3 is C1-3: C2-2: C3-3 = 3:4:3) and 50 parts increase Thick water (guar gum with a mass concentration of 2%) is mixed evenly to obtain a viscous high-concentration emulsified cream M3;

(2) 10 parts of polyether modified silicone oil emulsifier (the mass ratio of C1-3, C2-2, and C3-3 is C1-3: C2-2: C3-3 = 3:4:3) and 140 parts of poly The vinyl lipid polymer (molecular weight is 50,000) is evenly mixed to obtain mixture N3;

(3) Turn on the high-speed disperser and slowly add 260 parts of silicone paste A3 to M3 at a low speed of 400r/min, and then slowly add the mixture N3; after mixing, slowly increase the speed to 1100r/min for stirring;

(4) Slowly add 175 parts of water until the emulsion is completely turned to O/W state, increase the rotation speed to 1700r/min, and keep the rotation speed for 8 minutes. Slowly add the remaining 175 parts of water and keep the rotation speed for 15 minutes;

(5) Reduce the rotating speed to 400r/min, add 150 parts of thickening water and stir evenly to obtain the defoamer of the present invention.

Example 4

(1) 22.5 parts of polyether modified silicone oil emulsifier (the mass ratio of C1-4, C2-1, C3-1 is C1-4: C2-1: C3-1=1:3:60) and 48 parts increase Mix the thick water (3% carboxymethyl cellulose with a mass concentration of 3%) evenly to obtain a viscous high-concentration emulsified cream M4;

(2) 7.5 parts of polyether modified silicone oil emulsifier (the mass ratio of C1-4, C2-1, C3-1 is C1-4: C2-1: C3-1=1:3:60) and 50 parts of polyether The vinyl lipid polymer (molecular weight is 8000) is evenly mixed to obtain the mixture N4;

(3) Turn on the high-speed disperser and slowly add 236 parts of silicone paste A4 to M4 at a low speed of 450r/min, and then slowly add the mixture N4; after mixing, slowly increase the speed to 1100r/min for stirring;

(4) Slowly add 246 parts of water until the emulsion is completely turned to O/W state, increase the rotation speed to 1600r/min, and keep the rotation speed for 8 minutes. Slowly add the remaining 246 parts of water and keep the rotation speed for 18 minutes;

(5) Reduce the rotating speed to 480r/min, add 144 parts of thickening water and stir evenly to obtain the defoamer of the present invention.

Example 5

(1) 37.6 parts of polyether modified silicone oil (the mass ratio of C1-1, C2-3, C3-4 is C1-1: C2-3: C3-4 = 3:4:10) and 43 parts of thickening water (Polyacrylic acid with a mass concentration of 3%) mixed uniformly to obtain a viscous high-concentration emulsified cream M5;

(2) 9.4 parts of polyether modified silicone oil (the mass ratio of C1-1, C2-3, C3-4 is C1-1:C2-3:C3-4=3:4:10) and 149 parts of polyvinyl Lipid polymers (molecular weight 80,000) are mixed uniformly to obtain mixture N5;

(3) Turn on the high-speed disperser and slowly add 208 parts of silicone paste A5 to M5 at a low speed of 420r/min, and then slowly add the mixture N5; after mixing, slowly increase the speed to 1000r/min for stirring;

(4) Slowly add 212 parts of water until the emulsion is completely turned to O/W state, increase the rotation speed to 1600r/min, and keep the rotation speed for 6 minutes. Slowly add the remaining 212 parts of water and keep the rotation speed for 13 minutes;

(5) Reduce the rotating speed to 400r/min, add 129 parts of thickening water and stir evenly to obtain the defoamer of the present invention.

Comparative example 1

(1) 50 parts of polyether modified silicone oil emulsifier (the mass ratio of C1-1, C2-1, C3-3 is C1-1: C2-1: C3-1=1: 9:60) and 57.5 parts increase Thick water (polyacrylate with a mass concentration of 1%) is mixed uniformly to obtain a viscous high-concentration emulsified cream M6;

(2) Turn on the high-speed machine to disperse and slowly add 220 parts of silicone paste A1 to M6 at a low speed of 300r/min, and after mixing, slowly increase the speed to 1000r/min for stirring;

(3) Slowly add 250 parts of water until the emulsion is completely turned to O/W state, increase the rotation speed to 1500r/min, and keep the rotation speed for 5 minutes. Slowly add the remaining 250 parts of water. Maintain the speed for 10 minutes;

(4) Reduce the rotating speed to 300 r/min, add 172.5 parts of thickening water and stir evenly to obtain the defoamer of the present invention.

Comparative example 2

(1) 36 parts of polyether modified silicone oil emulsifier (the mass ratio of C1-1, C2-1 is C1-1: C2-1: C3-1=1: 9) and 57.5 parts of thickening water (the mass concentration is 1% polyacrylate) mixed uniformly to obtain a viscous high-concentration emulsified cream M7;

(2) 4 parts of polyether modified silicone oil emulsifier (the mass ratio of C1-1, C2-1 is C1-1: C2-1: C3-1=1: 9) and 100 parts of polyvinyl lipid polymer (Molecular weight is 5000) Mix evenly to obtain mixture N6;

(3) Turn on the high-speed machine to disperse at a low speed of 300r/min, slowly add 120 parts of silicone paste A1 to M6, and then slowly add the mixture N6; after mixing, slowly increase the speed to 1000r/min for stirring;

(4) Slowly add 250 parts of water until the emulsion is completely turned to O/W state, increase the speed to 1500r/min, and keep the speed for 5 minutes. Slowly add the remaining 250 parts of water. Maintain the speed for 10 minutes;

(5) Reduce the rotating speed to 300 r/min, add 172.5 parts of thickening water and stir evenly to obtain the defoamer.

Comparative example 3

(1) 40 parts of polyether modified silicone oil emulsifier C1-3 and 50 parts of thickening water (guar gum with a mass concentration of 2%) are mixed uniformly to obtain a viscous high-concentration emulsified cream M8;

(2) 10 parts of polyether modified silicone oil emulsifier C1-3 and 140 parts of polyvinyl lipid polymer (molecular weight 50,000) are mixed uniformly to obtain mixture N7;

(3) Turn on the high-speed disperser and slowly add 260 parts of silicone paste A3 to M7 at a low speed of 400r/min, and then slowly add the mixture N7; after mixing, slowly increase the speed to 1100r/min for stirring;

(4) Slowly add 175 parts of water until the emulsion is completely turned to O/W state, increase the rotation speed to 1700r/min, and keep the rotation speed for 8 minutes. Slowly add the remaining 175 parts of water and keep the rotation speed for 15 minutes;

(5) Reduce the speed to 400r/min, add 150 parts of thickening water and stir evenly to obtain the defoamer.

Comparative example 4

(1) 22.5 parts of polyether modified silicone oil emulsifier (the mass ratio of C1-4, C2-1, C3-1 is C1-4: C2-1: C3-1=1:3:60) for use;

(2) 7.5 parts of polyether modified silicone oil emulsifier (the mass ratio of C1-4, C2-1, C3-1 is C1-4: C2-1: C3-1=1:3:60) and 50 parts of polyether Vinyl lipid polymer (molecular weight 8000) is mixed uniformly to obtain mixture N4

(3) Turn on the high-speed disperser and slowly add 236 parts of silicone paste A4 to the polyether modified silicone oil emulsifier at a low speed of 450r/min, and then slowly add the mixture N4; after mixing, slowly increase the speed to 1100r/min. Stir

(4) Slowly add 246 parts of water until the emulsion is completely turned to O/W state, increase the rotation speed to 1600r/min, and keep the rotation speed for 8 minutes. Slowly add the remaining 246 parts of water and keep the rotation speed for 18 minutes;

(5) Reduce the rotating speed to 480r/min, add 192 parts of thickening water and stir evenly to obtain the defoamer of the present invention.

Comparative example 5

(1) 37.6 parts of polyether modified silicone oil (the mass ratio of C1-1, C2-3, C3-4 is C1-1: C2-3: C3-4 = 3:4:10) and 43 parts of thickening water (Polyacrylic acid with a mass concentration of 3%) mixed uniformly to obtain a viscous high-concentration emulsified cream M5;

(2) 9.4 parts of polyether modified silicone oil (the mass ratio of C1-1, C2-3, C3-4 is C1-1: C2-3: C3-4 = 3:4:10) and 149 parts of polyvinyl Lipid polymers (molecular weight 80,000) are mixed uniformly to obtain mixture N5;

(3) Turn on the high-speed disperser and slowly add 208 parts of silicone paste A5 to M5 at a low speed of 420r/min, and then slowly add the mixture N5; after mixing, slowly increase the speed to 1000r/min for stirring;

(4) Slowly add 424 parts of water until the emulsion is completely turned to O/W state, increase the speed to 1600r/min, and keep the speed for 6min;

(5) Reduce the rotating speed to 400r/min, add 129 parts of thickening water and stir evenly to obtain the defoamer of the present invention.

Comparative example 6

(1) 50 parts of polyether modified silicone oil emulsifier (the mass ratio of C1-1, C2-1, C3-3 is C1-1: C2-1: C3-1=1: 9:60) and 57.5 parts increase Thick water (polyacrylate with a mass concentration of 1%) is mixed uniformly to obtain a viscous high-concentration emulsified cream M6;

(2) Turn on the high-speed machine to disperse and slowly add 120 parts of silicone paste A1 to M6 at a low speed of 300r/min, and then slowly add 100 parts of polyvinyl lipid polymer (molecular weight 5000); slowly increase after mixing. Stir at 1000r/min;

(3) Slowly add 250 parts of water until the emulsion is completely turned to O/W state, increase the rotation speed to 1500r/min, and keep the rotation speed for 5 minutes. Slowly add the remaining 250 parts of water. Maintain the speed for 10 minutes;

(4) Reduce the rotating speed to 300r/min, add 172.5 parts of thickening water and stir evenly to obtain the defoamer of the present invention.

Comparative example 7 (high temperature emulsification)

Reference patent CN103041622B embodiment 1 preparation

Defoaming performance test

Anti-foaming performance test method:

Black liquor defoaming performance test:

Test temperature: 85℃; test medium type and dosage: homemade black liquor, 1000g

Method and dosage of defoamer: 10% diluent, dosage, 0.4mL.

The performance of the defoamer is measured by the method of cyclic bubbling. Add 1000ml of black liquor to the circulatory bubbling device and heat it to 85°C, turn on the flow pump, and circulate to the foam volume of 260ml at a flow rate of 8/L min, add 10% Diluent, 0.4ml defoamer, record the change of foam volume with time. In the same time, the smaller the volume, the better the foam suppression performance; the longer it takes for the foam to reach 260ml again, the better the foam suppression performance.

Claims (7)

A silicone composite emulsion type defoamer for the paper industry, which is characterized in that it comprises the following components: A: Silicone paste. The said silicone paste is made of hydrogen-containing silicone oil, hydroxy silicone oil, hydrophobic white carbon black, and silicone resin under the action of a catalyst. This component accounts for 10% to 26% of the total mass of the defoamer; B: Polyvinyl ester polymer. The polyvinyl ester polymer is designed to produce polyethylene by solution radical polymerization of acrylate monomers and allyl polyether monomers through molecular structure design. Base ester, this component accounts for 5% to 15% of the total mass of the defoamer; C: Polyether modified silicone oil emulsifier, said polyether modified silicone oil is prepared from hydrogen-containing silicone oil, vinyl-containing polyether, and divinyl-terminated polydimethylsiloxane through hydrosilylation reaction , The structural formula is as follows

Wherein, R is a hydrogen atom, a methyl group; subscripts x, y, z, p are the degree of polymerization of the siloxy link, x is an integer from 1 to 50, y is an integer from 20 to 500, and z is from 1 to 4 , P is an integer from 200 to 500; subscripts n and m are respectively the degree of polymerization of ethylene oxide and propylene oxide, n is an integer from 1 to 25, and m is an integer from 0 to 5; subscript q is -CH _{The degree of polymerization of 2} is an integer from 1 to 3; by adjusting the values of n, m, x, y, p, z, three polyether modified silicone oils C1, C2, C3 with different cloud points and different HLB values can be obtained. The component accounts for 3% to 5% of the total mass of the defoamer, and the emulsifier C is used in two parts; D: Thickening water: The thickening water is prepared from water and a thickening agent, wherein the thickening agent is selected from xanthan gum, guar gum, carboxymethyl cellulose, hydroxyethyl cellulose, and methyl fiber Polyacrylic acid, polyacrylamide and polyacrylate, the water is deionized water; the mass concentration of the thickening water is 1% to 4%; the amount of thickener accounts for 15% to 23% of the total mass of the defoamer; Two parts D1 and D2 are used for thickening water; E: Water, the water is deionized water, the amount is 35%-50% of the total mass of the defoamer, and the water is two parts E1 and E2. A silicone composite emulsion type defoamer for the papermaking industry according to claim 1, wherein the polyvinyl ester polymer has a molecular weight of 5,000 to 100,000. A silicone composite emulsion type defoamer for the papermaking industry according to claim 1, characterized in that the HLB of the polyether modified silicone oil emulsifier C is 8.5-10.5, and the HLB value of C1 is 2 5. The HLB value of C2 is 6-8, and the HLB value of C3 is 9-20. A silicone composite emulsion type defoamer for the papermaking industry according to claim 1, characterized in that the polyether modified silicone oil emulsifier C, the first part of which accounts for 70-90% of the total mass of the emulsifier C , The amount of the second part accounts for 10-30% of the total mass of emulsifier C. A silicone composite emulsion type defoamer for the papermaking industry according to claim 1, wherein the thickening water D1 and D2 account for 1/4 and 3/4 of the total mass of the thickening water, respectively. A silicone composite emulsion type defoamer for the papermaking industry according to claim 1, characterized in that the water E1 and E2 respectively account for half of the total mass of water. The preparation method of a silicone composite emulsion type defoamer for the papermaking industry according to claim 1 is as follows: (1) The first part of the emulsifier C and the polyether modified silicone oil emulsifier and the thickening water D1 are mixed uniformly to form a viscous high-concentration emulsified paste M; (2) The second part of the emulsifier C and the component B polyvinyl ester polymer are mixed uniformly to obtain a mixture N; (3) Turn on the high-speed disperser and slowly add the component A silicone paste to M at a low speed of 300-500r/min, then slowly add the mixture N, and slowly increase the speed to 1000-1200r/min; (4) Slowly add water E1 until the emulsion is completely turned to O/W state, increase the speed to 1500-1800r/min. Keep the speed for 5min-10min, slowly add the remaining water E2, keep the speed for 10min-20min; reduce the speed to 300 -500r/min, add the remaining thickening water D2 and stir evenly to obtain the defoamer.