JP3426298B2 - Silicone emulsion type defoamer and defoaming method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a silicone emulsion type defoaming agent which is excellent in the initial defoaming effect immediately after being added to an aqueous foaming liquid and the durability of the defoaming effect thereafter, and a use thereof. It is related to the defoaming method.

[0002]

2. Description of the Related Art Conventionally, various antifoaming agents containing a silicone composition as an active ingredient are known, such as oil type, liquid type, compound type and emulsion type. Among these, as an antifoaming agent for an aqueous foaming liquid, an emulsion type antifoaming agent composition is preferably used, since high dispersibility is obtained in the aqueous foaming liquid. Came. As an emulsion type antifoaming agent, those obtained by emulsifying silicone oil and silica in water with various surfactants are known.

The emulsion type defoaming agent composition is generally used as an oil-in-water type emulsion, and various emulsion type defoaming agents are widely used. And
In the use of this type of defoaming agent, the defoaming agent is used for the purpose of facilitating the management of dispersibility in a foaming system such as a foaming liquid and the addition amount of the defoaming agent which is usually a small amount, and improving the economical efficiency. To a dilute concentration of a few percent or less,
It is preferred to add it to the effervescent liquid.

[0004]

However, in the conventional emulsion type silicone antifoaming agent, the concentration thereof is lowered by diluting the emulsion, which is generally added to the foaming liquid, with water. The method of improving the initial defoaming effect by improving the dispersibility of However, since the defoaming effect that is continuously exerted (hereinafter, simply referred to as "persistent defoaming effect") is controlled by the total concentration of the active ingredients of the added defoaming agent, the dilution ratio is By changing it, it is practically impossible to obtain the improvement of the sustained defoaming effect. The present invention has been made based on the above circumstances, and particularly to a water-based foaming liquid, a silicone emulsion defoaming agent that exhibits excellent initial defoaming effect and sustained defoaming effect, and The purpose is to provide a defoaming method.

[0005]

The silicone emulsion type defoaming agent of the present invention comprises 100 parts by weight of a silicone defoaming composition containing polyorganosiloxane as a main component.
Silicon atoms and porosities in siloxanes of silicone oil
The carbon atom in the lyoxyalkylene group is silicon-carbon.
A main agent composed of 3 to 300 parts by weight of a polyoxyalkylene-modified silicone oil in which a polyoxyalkylene group is bonded by elementary bond is emulsified in water without compatibility, and the content ratio of the main agent is Is 2
A silicone-based emulsion having a content of 0% by weight or more and 70% by weight or less, wherein the silicone-based emulsion changes the particle size of its emulsion particles when added to a foamable liquid having a liquid temperature of 25 ° C. or more, It is characterized in that the rate of change satisfies the condition shown in the following formula (i). Formula (i) (b / a) ≧ 2 (where a represents the particle size of emulsion particles before addition to the foaming liquid, and b represents the particle size of emulsion particles immediately after addition to the foaming liquid. )

The foamable liquid preferably contains at least one selected from cellulosic compounds and lignin compounds.

The defoaming method of the present invention is characterized in that the silicone emulsion type defoaming agent comprising the above-mentioned silicone emulsion is directly added to the foamable liquid having a liquid temperature of 25 ° C. or higher.

It is preferable that the foamable liquid contains at least one selected from cellulosic compounds and lignin compounds.

Regarding the silicone emulsion defoaming agent of the present invention, "immediately after addition" means that the silicone emulsion defoaming agent according to the present invention is added to the foaming liquid and then 5
It means a certain point in time until a minute elapses, and "directly adding" means that the silicone emulsion defoaming agent according to the present invention is added to a foaming liquid without further diluting with water. Say how to do. Here, in the case where the silicone emulsion type antifoaming agent according to the present invention has a high concentration, the silicone emulsion is diluted with water within the range until the content ratio of the main agent becomes 20% by weight or more. It goes without saying that the method of adding the above to the foaming liquid is also included in the “direct addition” method.

The present inventors have studied silicone-based emulsion type antifoaming agents that exhibit an excellent long-lasting defoaming effect especially for foamable liquids. When added to, the particle size of the emulsion particles, which is the main ingredient of the silicone emulsion defoamer in the state of being added to the foaming liquid, correlates with the concentration of the main ingredient of the silicone emulsion defoamer. And dispersant (emulsifier) such as polyoxyalkylene-modified silicone oil
A defoaming agent in which a silicone-based compound is emulsified by using a base compound with a concentration of the main agent above a specific concentration, the particle size of the emulsion particles increases when added directly to the foaming liquid, and It has been found that they exhibit an improved persistent defoaming effect on liquids and has completed the present invention.

The present invention will be specifically described below.
The silicone emulsion defoaming agent of the present invention comprises a silicone defoaming composition and a polyoxyalkylene-modified silicone oil as main components, and the main component is an emulsion at a ratio of 20% by weight or more and 70% by weight or less in water. When dispersed in a foamable liquid having a liquid temperature of 25 ° C. or higher, the particle size of emulsion particles changes, and the ratio of the change is expressed by the following formula (i The conditions shown in () are satisfied. Formula (i) (b / a) ≧ 2 (where a represents the particle size of the emulsion particles before addition to the expandable liquid, and b represents the particle size of the emulsion particles immediately after addition to the expandable liquid). ) That is, the particle size of the emulsion particles constituting the silicone-based emulsion type defoaming agent of the present invention is such that the defoaming agent has a liquid temperature of 2
It increases when it is added to an aqueous foaming liquid at 5 ° C. or higher, and becomes twice or more the particle size before addition at a certain time point until 5 minutes have elapsed since the addition.

The silicone-based defoaming composition contains polyorganosiloxane as a main component.
Examples thereof include silicone compounds obtained by blending polyorganosiloxane with a filler such as silica.

Specifically, for example, Japanese Examined Patent Publication No. 27-2263.
Of polydiorganosiloxane and silica as described in JP-B No. 45-23613 and JP-A No. 60-251906, and silica.
Further containing polysiloxane resin, Japanese Patent Publication No. 5
2-19836 and JP-A-63-147507.
Examples thereof include those containing polydiorganosiloxane as described in JP-A No. 1993-242, silica, and a polysiloxane resin and a polyoxyalkylene-polysiloxane copolymer, and others.

The polyoxyalkylene-modified silicone oil, which constitutes the main component together with the above silicone-based defoaming composition, has a silicon-carbon bond in the molecule due to the silicon atom in the siloxane of the silicone oil and the carbon atom in the polyoxyalkylene group. through with silicone oil bonded polyoxyalkylene group, i.e. silicoaluminophosphates
Atoms and Polyoxyls in the Siloxane of Corn Oil
The carbon atom in the alkylene group is a silicon-carbon bond
The polyoxyalkylene group is bound by
Is a polyoxyalkylene-modified silicone oil ,
It is water-soluble at room temperature, specifically 25 ° C., and is preferably nonionic.

The polyoxyalkylene-modified silicone oil is, for example, a copolymer of a silicone oil composed of linear or branched siloxane and polyoxyalkylene, and there are various kinds.
Those represented by the following formulas are particularly preferable. ^{_{R 2 3 SiO- (R 1 2}} SiO) r - (R 1 ASiO)
_S —SiR ² ₃ (In the formula, R ¹ represents the same or different monovalent hydrocarbon group, but is preferably a methyl group. R ² is the same or different monovalent hydrocarbon group or A. , A
Is a group represented by R ³ G. Here, R ³ represents a divalent hydrocarbon group, and G represents a polyoxyalkylene group containing at least one alkylene oxide having 2 to 5 carbon atoms such as ethylene oxide and propylene oxide. Moreover, r is an integer of 1 to 500 and s is an integer of 1 to 50. )

Specific examples of the polyoxyalkylene-modified silicone oil preferably used in the present invention include:
The compounds represented by the following chemical formula 1 can be mentioned, but the invention is not limited thereto. It is also possible to use two or more compounds within the above range in combination.

[0017]

[Chemical 1] In Chemical formula 1, x is 20 to 160, y is 1 to 25, and the value of x / y is 50 to 2. A, for example _{- (CH 2) 3 O- (} CH 2 CH 2 O) m - (CH 2 C
A _{H 2 CH 2 O) n -R} 4, m is 7 to 40, n is 0 to 40, the value of m + n is at least 1, even one that is graft polymerized may be one which is random polymerization. R ⁴ represents a hydrogen atom or a monovalent group. Suitably, m is 7-30 and n is 0-30.

In the silicone emulsion type defoaming agent of the present invention, the content ratio of the main component composed of the above silicone defoaming composition and polyoxyalkylene-modified silicone oil is set to 20% by weight or more and 70% by weight or less. It
When the content ratio of the main agent is less than 20% by weight, the sustained defoaming effect becomes insufficient, and when it exceeds 70% by weight, the dispersibility in the foaming liquid becomes insufficient, and it is practically used as a defoaming agent. Inferior in sex.

Further, the blending ratio of the polyoxyalkylene-modified silicone oil in the above-mentioned main component is 3 to 300 parts by weight with respect to 100 parts by weight of the silicone antifoam composition. Usually, the blending ratio is in the range of 25 to 300 parts by weight, preferably 50 to 150 parts by weight, based on 100 parts by weight of the silicone-based defoaming composition.

In the present invention, as the constituent of the emulsion particles of the silicone-based emulsion type defoaming agent, an additive component other than the main component can be blended. The additive component is not particularly limited as long as it can form oil-in-water type emulsion particles together with the main component. Specific examples of the additive components include the following.

(A) Organic defoaming compounds or compounds thereof, for example, compounds consisting of terpene oil and silica, and compounds consisting of terpene oil and ethylenebisstearyl amide. (B) Synthetic organic oil or a compound thereof, for example, a compound composed of α-olefin and silica. (C) Mineral oil or a compound thereof, for example, a compound composed of mineral oil and silica. (D) Organic wax For example, paraffin wax. (E) Modified silicone that is sparingly soluble or insoluble in water at room temperature

These additional components are not limited to only one type,
A plurality of them may be used in combination, and they are preferably used in a proportion of 1 to 50% by weight based on the silicone emulsion defoaming agent.

The method for producing a silicone emulsion defoaming agent of the present invention comprises a step of emulsifying the above silicone defoaming composition and polyoxyalkylene-modified silicone oil in water. Basically, a polyoxyalkylene-modified silicone oil and water are added to a silicone-based defoaming composition to form an emulsion. As an actual method, water may be added after mixing the silicone-based defoaming composition and the polyoxyalkylene-modified silicone oil. Alternatively, water and polyoxyalkylene-modified silicone may be added to the silicone-based defoaming composition. A mixture with oil may be added, and further, the silicone-based defoaming composition, polyoxyalkylene-modified silicone oil, and water may be simultaneously added and mixed.

Means for emulsifying the above silicone-based defoaming composition, polyoxyalkylene-modified silicone oil, and water are, for example, JP-A-63-44905.
No. 6-147507, examples of which are commonly used homomixers,
A homogenizer, a colloid mill, etc. can be used.

In the above emulsification,
A nonionic surfactant used for usual emulsification (emulsification) can also be used.

By emulsifying the main agent in water according to the above-mentioned production method and adjusting the content ratio of the main agent in the emulsion to 20% by weight or more and 70% by weight or less, an improved sustained defoaming effect can be obtained, and foaming can be achieved. It is possible to obtain a silicone-based emulsion type defoaming agent having a sufficient dispersibility in a volatile liquid.

In the defoaming method using the silicone emulsion defoaming agent of the present invention, a silicone defoaming composition containing the above polyorganosiloxane as a main component,
A main agent composed of a polyoxyalkylene-modified silicone oil and water are mixed to form an emulsion, which is directly added to a foaming liquid having a liquid temperature of 25 ° C. or higher as an antifoaming agent. Thus, by directly adding to the foamable liquid having a liquid temperature of 25 ° C. or higher, an excellent initial defoaming effect is exhibited,
Further, it has a long-lasting defoaming effect and can maintain a stable defoaming state.

Although the reason why the silicone emulsion type antifoaming agent of the present invention provides an improved sustained defoaming effect has not been elucidated in detail, the antifoaming agent was added to an aqueous foaming liquid. It is characteristic that sometimes the phenomenon that the particle size of the emulsion particles becomes large occurs.

The particle size of emulsion particles constituting the silicone emulsion type defoaming agent of the present invention is usually several μm to several tens μm at the time of production, and 1 μm for special products.
m or less, but when the antifoaming agent is added to an aqueous foaming liquid having a liquid temperature of 25 ° C. or higher, the particle size of emulsion particles of the silicone-based emulsion increases, and
It is more than doubled at a certain point in time until a minute has passed. Such a phenomenon of increasing the particle size of emulsion particles is a phenomenon specifically obtained when the above-mentioned polyoxyalkylene-modified silicone oil is used in a specific ratio.

Specifically, as will be clear from the description of the examples below, when the silicone emulsion type defoaming agent of the present invention is added to an aqueous foaming liquid having a liquid temperature of 25 ° C. or higher, When the particle size of the emulsion particles forming the dispersed phase in the foamable liquid becomes large due to the action of the polyoxyalkylene-modified silicone and this particle size increasing phenomenon is observed at a specific rate, excellent sustainability is achieved. A defoaming effect is obtained. From such a point, according to the silicone emulsion type defoaming agent of the present invention in which the ratio of the main agent to water is within the above-mentioned specific range, the phenomenon of increasing the particle size of the emulsion particles is surely caused. It is considered that the improved sustained defoaming effect is exhibited.

As described above, in the silicone emulsion type defoaming agent of the present invention, it is very surprising that the change in the particle size of the emulsified main agent particles has a great influence on the sustained defoaming effect. Is. This is because, in the past, the sustained defoaming effect of the defoaming agent depends on the total amount of the active ingredients added to the foaming liquid, but the size of the particles of the defoaming agent added is large. As such, it was believed to be largely independent of the extent of the sustained defoaming effect. However, as in the present invention, by using a silicone emulsion type defoaming agent in which the particle size state of the emulsion particles satisfies a specific condition, it is possible to obtain an excellent sustained defoaming effect as described above. You can do it.

The silicone emulsion type antifoaming agent of the present invention can be used in a relatively high concentration and has good dispersibility in an aqueous foaming liquid. is there. Therefore, in the defoaming method using the silicone emulsion defoaming agent, it is not necessary to dilute when applied to an aqueous foaming liquid, and the diluting operation usually required is omitted. In this respect, there is an advantage that it can be used very easily.

The silicone emulsion type antifoaming agent according to the present invention is particularly effective for a foaming liquid containing at least one selected from a cellulosic compound and a lignin compound. This effervescent liquid is specifically
At least one selected from a cellulosic compound and a lignin compound is dissolved in water. By adding the silicone-based emulsion type defoaming agent according to the present invention to this foaming liquid according to the method described above, an excellent sustained defoaming effect can be obtained.

In the present invention, the addition ratio of the silicone emulsion type defoaming agent to the foaming liquid is usually such that the ratio of the main agent of the defoaming agent to the foaming liquid is several ppm to.
Although it is a range of several hundred ppm, preferably several ppm to several tens ppm, it is not particularly limited to this range,
It can be appropriately changed depending on the constituent components of the foamable liquid, various conditions for adding the antifoaming agent, the purpose of addition, and the like.

[0035]

According to the present invention, the obtained silicone emulsion type defoaming agent has a good dispersibility especially in an aqueous foaming liquid and exhibits an excellent initial defoaming effect. It has a long-lasting defoaming effect and maintains a stable defoaming state. Since this silicone-based emulsion type defoaming agent can add the defoaming agent directly to the foaming liquid, the defoaming agent can be added during transportation, storage, preparation or other product manufacturing process. In each of the above aspects, excellent effects can be obtained in terms of economic efficiency, work efficiency, and the like.

[0036]

Example 1 [Preparation of Silicone Emulsion Defoaming Agent] 378 g of trimethylsilyl end-capped polydimethylsiloxane,
180 g of hydroxyl-terminated polydimethylsiloxane and 18 g of ethyl polysilicate are mixed by heating, and 30 g of silica and 30-hydroxylated hydroxyl-terminated polydimethylsiloxane are mixed in this mixture.
5 parts by weight of the silicone-based defoaming composition obtained by further blending g with the compound represented by the structural formula of the above-mentioned chemical formula 1
A is the _{(CH 2) 3 O- (CH} 2 CH 2 O) m - (CH 2 CH
A _{2 CH 2 O) n -H,} x is 90 to 105, y is 7.5 to 10.5, m
Of 10 to 30 and n of 10 to 30 and 5 parts by weight of a polyoxyalkylene-modified silicone oil are used as a main component, and this is gradually added to 15 parts by weight of water over 5 minutes, and then 10 minutes. By continuing stirring, the main agent was dispersed in water to form an emulsion, and a silicone emulsion defoamer was prepared.

[Preparation of Aqueous Effervescent Liquid] An effervescent liquid prepared by dissolving a cellulose compound and a lignin compound in water was prepared. The total concentration of the cellulosic compound and the lignin compound in this aqueous foamable liquid was 0.4.
% By weight.

[Defoaming Effect Test] Using the test apparatus shown in FIG. 1, the above-mentioned foaming liquid was placed in a glass cylinder 10 with a diameter of 50 mm which was erected in a constant temperature bath 20 upright.
00 g of the foamable liquid was kept at a temperature of 70 ° C. ± 1 ° C., and the foamable liquid was flown at a flow rate of 2.0 liters per minute by the non-connection type magnet pump 40 through the circulation path pipe 30. By performing a foaming operation in which the test liquid from the outlet 35 of the circulation path pipe 30 is constantly dropped onto the surface of the liquid phase L in the glass cylinder 10, a foaming state is generated in the glass cylinder 10. Was formed. After the foaming operation was continued for 10 minutes, the prepared silicone emulsion defoamer was added by a micropipette in an amount such that the total amount of the main component added to the foaming liquid was 5 ppm. Furthermore, after the addition of the silicone-based emulsion type defoaming agent, a stable residual foam layer formed so as to remain stably on the liquid phase L in the glass cylinder 10 for a predetermined circulation time (the upper surface thereof is shown by a chain line). ) The amount of B was measured on the scale of the glass cylinder 10 to evaluate the initial antifoaming effect and the persistent antifoaming effect.

Further, the particle size of the main agent in the silicone emulsion type antifoaming agent and the particle size of the main agent in the foaming liquid at a predetermined time during the execution of the defoaming effect test are measured by Microtrac Particle Size Analyzer Model 7995-10.
It was measured using SRA. The results are shown in Table 1 below.

Example 2 A silicone emulsion defoamer was prepared in the same manner as in Example 1 except that the amount of water used was changed to 10 parts by weight. A defoaming effect test was conducted after addition. The results are shown in Table 1.

Example 3 A silicone emulsion defoamer was prepared in the same manner as in Example 1 except that the amount of water used was 23.3 parts by weight.
This was added to the foaming liquid in the same manner as in Example 1 and a defoaming effect test was conducted. The results are shown in Table 1.

Comparative Example 1 A silicone emulsion defoamer was prepared in the same manner as in Example 1 except that the amount of water used was changed to 90 parts by weight. A defoaming effect test was conducted after addition. The results are shown in Table 1.

Comparative Example 2 Instead of the polyoxyalkylene-modified silicone oil, the following formula (CH ₂ CH ₂ O) _A — (CH ₂ CH ₂ CH ₂ O) _B — was used.
(CH ₂ CH ₂ O) _C (In the formula, the value of A + C is 45 or more and 55 or less, and B is 3
It is an integer of 5 or more and 45 or less. A silicone emulsion defoamer was prepared in the same manner as in Comparative Example 1 except that the emulsifier shown in 1) was used, and this was added to the foaming liquid in the same manner as in Example 1 to carry out the defoaming effect test. went. The results are shown in Table 1.
Shown in.

Comparative Example 3 A silicone emulsion defoamer was prepared in the same manner as in Comparative Example 2 except that the amount of water used was 23.3 parts by weight.
This was added to the foaming liquid in the same manner as in Example 1 and a defoaming effect test was conducted. The results are shown in Table 1.

Comparative Example 4 A silicone emulsion type defoaming agent was prepared in the same manner as in Comparative Example 2 except that the amount of water used was 15 parts by weight. A defoaming effect test was conducted after addition. The results are shown in Table 1.

Comparative Example 5 A silicone emulsion defoamer was prepared in the same manner as in Comparative Example 2 except that the amount of water used was changed to 10 parts by weight. A defoaming effect test was conducted after addition. The results are shown in Table 1.

[0047]

[Table 1]

In Table 1 above, the elapsed time is 0.5 to
From the numerical value of the stable residual foam layer volume at the time of 1 minute, it was possible to obtain an excellent initial defoaming effect by using the silicone emulsion type defoaming agent of the present invention, and moreover, the sustained defoaming effect was large. It is clear that a stable defoaming state can be maintained. Furthermore, the particle size of the emulsion particles of the defoaming agent is increased as compared with that before the addition to the foamable liquid, whereby a more excellent initial defoaming effect and an excellent persistent defoaming effect can be obtained. To be understood.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of the configuration of a test apparatus used for investigating the defoaming effect of a silicone emulsion defoamer.

[Explanation of symbols]

10 Glass cylinder with scale 20 Constant temperature bath 30 Circulation path pipe 35 Exit 40 Non-Connectable Magnet Pump L Liquid Phase B Stable residual foam layer

─────────────────────────────────────────────────── --Continued from the front page (56) Reference JP-A-53-34854 (JP, A) JP-A-3-157106 (JP, A) JP-A-62-277110 (JP, A) JP-A-56- 48211 (JP, A) Special table HEI 6-510475 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B01D 19/00-19/04

Claims (4)

(57) [Claims] 100 parts by weight of 1. A silicone as a main component polyorganosiloxane antifoam composition, silicone
Atoms and polyoxy in siloxanes of vinyl oil
The carbon atom in the alkylene group is a silicon-carbon bond.
Polyoxyalkylene-modified silicone oil is a polyoxyalkylene group by Rukoto bonded 3-30
The main ingredient consisting of 0 parts by weight is emulsified in water without compatibility, and the content of the main ingredient is 20% by weight.
The content of the silicone-based emulsion is 70% by weight or less, and when the silicone-based emulsion is added to a foaming liquid having a liquid temperature of 25 ° C. or more, the particle size of the emulsion particles changes and A silicone emulsion type defoaming agent, characterized in that the proportion thereof satisfies the condition shown in the following formula (i). Formula (i) (b / a) ≧ 2 (where a represents the particle size of emulsion particles before addition to the foaming liquid, and b represents the particle size of emulsion particles immediately after addition to the foaming liquid. ) 2. The silicone emulsion defoamer according to claim 1, wherein the foamable liquid contains at least one selected from a cellulose compound and a lignin compound. 3. A defoaming method comprising directly adding the silicone emulsion type defoaming agent comprising the silicone emulsion according to claim 1 to a foaming liquid having a liquid temperature of 25 ° C. or higher. 4. The defoaming method according to claim 3, wherein the foamable liquid contains at least one selected from a cellulosic compound and a lignin compound.