WO2022165929A1

WO2022165929A1 - Preparation method for super-hydrophobic acrylic emulsion

Info

Publication number: WO2022165929A1
Application number: PCT/CN2021/081161
Authority: WO
Inventors: 周健彬; 房迎春
Original assignee: 上海保立佳新材料有限公司
Priority date: 2021-02-02
Filing date: 2021-03-16
Publication date: 2022-08-11
Also published as: CN112940167A

Abstract

A preparation method for a super-hydrophobic acrylic emulsion, comprising: fully stirring and mixing an emulsifier accounting for 3-5% of the total monomer amount and water for 15-30 minutes, then adding an acrylate monomer, a special functional monomer and a molecular weight regulator, and stirring and emulsifying same for 30-60 minutes to obtain a pre-emulsion; uniformly stirring an emulsifier accounting for 3-5% of the total monomer amount and water, adding 3% of the pre-emulsion, and dropwise adding 60% of an initiator solution at the same time for a reaction for 7-15 minutes to prepare a seed emulsion; and continuously dropwise adding the residual pre-emulsion and the initiator solution into the seed emulsion, then maintaining the temperature and then cooling same to 60ºC for post-elimination, continuously maintaining the temperature for a reaction for 1 hour after the completion of the post-elimination, cooling same to 40ºC or below, and then filtering and discharging same to obtain a super-hydrophobic acrylic emulsion. The preparation method has a simple process, the product is green and environmentally friendly, which effectively solves the problem of the water resistance of an existing acrylic resin being not good enough, and provides a good surface effect of dripping water into beads and a good water resistance effect.

Description

A kind of preparation method of super-hydrophobic acrylic emulsion

technical field

The invention belongs to the technical field of emulsion preparation, in particular to a preparation method of a super-hydrophobic acrylic emulsion.

Background technique

At present, in the coatings industry, with the enhancement of people's awareness of environmental protection and the restriction of organic volatile solvents by environmental protection regulations, water dispersion systems or water-based coatings are replacing traditional coatings and paints with organic solvents as the dispersed phase in more and more fields. Base coatings have different requirements on the viscosity of the system during storage and construction. In many applications, a special superhydrophobic finish emulsion is required to achieve good waterproof and stain resistance, which is different from other superhydrophobic emulsions. , the acrylic super-hydrophobic emulsion is more used as an overcoat emulsion. On the basis of maintaining the original coating, it can achieve a very good super-hydrophobic effect through a very simple way of use. In the test of this emulsion, the higher the emulsion film Hardness, dripping into beads, reducing water residue, and excellent stain resistance.

At present, the preparation methods of acrylate emulsions include solution polymerization, precipitation polymerization, inverse emulsion polymerization and emulsion polymerization. Emulsion polymerization uses water as the dispersion medium, does not pollute the environment, and can avoid the environmental pollution problems caused by the use of organic dispersion medium, such as high cost, poor storage stability, and solvent removal. It has become the main synthesis method of acrylate thickeners. However, the existing emulsions have problems of poor hydrophobicity and poor stain resistance.

SUMMARY OF THE INVENTION

1. The technical problem to be solved by the invention

The purpose of the present invention is to solve the problem of poor anti-fouling effect of the existing emulsion due to poor hydrophobicity.

2. Technical solutions

For achieving the above object, the technical scheme provided by the invention is:

In the preparation method of the super-hydrophobic acrylic emulsion of the present invention, an emulsifier with a total monomer content of 3-5% and water are fully stirred and mixed for 15-30 minutes, and then acrylate monomers, special functional monomers, and molecular weight adjustment are added. The pre-emulsion is obtained by stirring and emulsifying the emulsifier for 30-60 minutes to obtain a pre-emulsion; the emulsifier and water with a total monomer content of 3-5% are stirred evenly, and then 3% of the pre-emulsion is added, and 60% of the initiator solution is added dropwise at the same time, and the reaction is 7- After 15 minutes, the seed emulsion was prepared; the remaining pre-emulsion and initiator solution were continuously added dropwise into the seed emulsion, and then the temperature was kept warm and cooled to 60°C for elimination. After the post-elimination was completed, the reaction was continued for 1 hour, and the temperature was lowered to below 40°C. , filter and discharge the material to obtain the super-hydrophobic acrylic emulsion.

Preferably, the emulsifier is an anionic emulsifier, and the anionic emulsifier is sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, ethoxylated alkyl sulfate sodium salt, and alkyl ether sulfate sodium salt , at least one of fatty alcohol ether sulfate sodium salt.

Preferably, the anionic emulsifier accounts for 2-10% of the total amount of the anionic emulsifier, acrylate monomers, special functional monomers and molecular weight regulators.

Preferably, the acrylate monomer is

One or more of styrene, methyl methyl, methacrylic acid and acrylic acid;

or

One or both of butyl acrylate, isooctyl acrylate and methyl methacrylate;

Or silicon-containing functional monomers or special resin cross-linking monomers.

Preferably, the special functional monomer is isobornyl methacrylate, including multiple groups of double bond functional monomers and hydrophobic macromolecular silicon-containing double bond polymerizable monomers, and the special functional monomers account for anionic emulsifier, 10-25% of the total amount of acrylate monomers, special functional monomers and molecular weight regulators.

Preferably, the molecular weight regulator is thiol and its derivatives or primary, secondary and tertiary thiols, thiol esters and thiol ethers with 5 to 14 carbon atoms, and the molecular weight regulator accounts for anionic emulsifier, acrylic acid 0.15-0.60% of the total amount of ester monomers, special functional monomers and molecular weight regulators.

Preferably, the initiator is one of sodium persulfate, ammonium persulfate, and potassium persulfate, and the initiator accounts for 5% of the total amount of anionic emulsifier, acrylate monomer, special functional monomer and molecular weight regulator. 0.1～0.6%.

Preferably, it specifically includes the following steps:

S100, preparing a pre-emulsion;

S200, preparing seed emulsion;

S300, emulsification reaction;

S400, post-elimination processing;

S500, cooling treatment.

Preferably, the emulsification reaction in the step S300 is to add the remaining pre-emulsion and the initiator solution dropwise to the prepared seed emulsion, the dropping time is 2-3 hours, and the dropping temperature is 80-90° C. When the remaining pre-emulsion is The resin cross-linking agent is added when the liquid and the initiator solution are added dropwise to one third, and the resin cross-linking agent is ethylene glycol dimethacrylate.

Preferably, the post-elimination treatment in the step S400 is specifically cooling the solution after the emulsification reaction to 60° C., adding an oxidant and a reducing agent and keeping the temperature for 1 hour, the oxidizing agent is tert-butyl hydroperoxide, and the reducing agent is FF6M .

3. Beneficial effects

Adopting the technical scheme provided by the present invention, compared with the prior art, has the following beneficial effects:

In the preparation method of the super-hydrophobic acrylic emulsion of the present invention, an emulsifier with a total monomer content of 3-5% and water are fully stirred and mixed for 15-30 minutes, and then acrylate monomers, special functional monomers, and molecular weight adjustment are added. The pre-emulsion is obtained by stirring and emulsifying the emulsifier for 30-60 minutes to obtain a pre-emulsion; the emulsifier and water with a total monomer content of 3-5% are stirred evenly, and then 3% of the pre-emulsion is added, and 60% of the initiator solution is added dropwise at the same time, and the reaction is 7- After 15 minutes, the seed emulsion was prepared; the remaining pre-emulsion and initiator solution were continuously added dropwise into the seed emulsion, and then the temperature was kept warm and cooled to 60°C for elimination. After the post-elimination was completed, the reaction was continued for 1 hour, and the temperature was lowered to below 40°C. , filter and discharge the material to obtain the super-hydrophobic acrylic emulsion. It is obtained through emulsion polymerization by selecting environmentally friendly emulsifiers, special functional monomers, acrylate monomers, molecular weight regulators and cross-linking agents for later resin molecules. Excellent effect, provides a very good dripping beading surface treatment, and excellent water resistance.

Description of drawings

Fig. 1 is the flow chart of a kind of preparation method of super-hydrophobic acrylic emulsion of the present invention.

Detailed ways

In order to facilitate understanding of the present invention, the present invention will be more fully described below with reference to the related drawings, in which several embodiments of the present invention are given, however, the present invention may be implemented in many different forms and is not limited to this The described embodiments are, rather, provided so that this disclosure will be thorough and complete.

It should be noted that when an element is referred to as being "fixed" to another element, it can be directly on the other element or intervening elements may also be present; when an element is referred to as being "connected" to another element, it may be be directly connected to another element or intervening elements may be present; the terms "vertical", "horizontal", "left", "right" and similar expressions are used herein for illustrative purposes only.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field of the present invention; the terms used herein in the description of the present invention are only used to describe specific embodiments is not intended to limit the invention; as used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Referring to accompanying drawing 1, the preparation method of a kind of super-hydrophobic acrylic emulsion of the present embodiment, the emulsifier and water of the total monomer amount of 3-5% are fully stirred and mixed for 15-30 minutes, and the ratio of the emulsifier is in different formulas There are different requirements, especially for particle size control and subsequent application performance, because in this application, the particle size will be controlled between 100-130nm as much as possible. If the amount of emulsifier is less than 3%, the synthesis stability will be affected. If the proportion of emulsifier is higher than 5%, the application properties of the emulsion such as water resistance will be greatly affected, so this comparison needs to be strictly controlled. Then add acrylate monomers, special functional monomers, molecular weight regulators, and stir and emulsify for 30-60 minutes to obtain a pre-emulsion. The reaction time for the emulsifier needs to be precisely controlled. If the emulsification time is higher than the required time, it will affect the The encapsulation effect of the emulsifier on the monomer is generally manifested in that the size of the relative micelle will be smaller. If the emulsification time is not enough, it will easily lead to poor emulsification effect, thereby affecting the stability of the micelle. 3-5% of emulsifier and water are stirred evenly, and then 3% of pre-emulsion is added, and 60% of initiator solution is added dropwise at the same time, and the seed emulsion is obtained after 7-15 minutes of reaction; The emulsion and the initiator solution are then kept warm and cooled to 60°C for elimination. After the post-elimination, the reaction is continued for 1 hour, cooled to below 40°C, and filtered to obtain the super-hydrophobic acrylic emulsion.

Specifically, the emulsifier is an anionic emulsifier, and the anionic emulsifier is sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, ethoxylated alkyl sulfate sodium salt, and alkyl ether sulfate sodium salt , at least one of fatty alcohol ether sulfate sodium salt.

Specifically, the anionic emulsifier accounts for 5-10% of the total amount of the anionic emulsifier, acrylate monomers, special functional monomers and molecular weight regulators, because in this aspect, the emulsion uses more functional monomers, while the functional monomers It is relatively more difficult to emulsifier, and anionic emulsifier is an emulsifier with relatively high emulsification efficiency, so the amount of anionic emulsifier added is relatively large when selecting, and if it is lower than this ratio, it will easily lead to slag, but Anionic emulsifiers are also emulsifiers with relatively large effects such as water resistance, so in the process of use, they will try to control within this ratio.

Specifically, the acrylate monomer is

One or more of styrene, methyl methyl, methacrylic acid and acrylic acid;

or

One or both of butyl acrylate, isooctyl acrylate and methyl methacrylate;

Specifically, the special functional monomer is isobornyl methacrylate. This functional monomer has a high TG ratio and other comprehensive effects, which can improve the hardness, scrub resistance, medium resistance, high gloss and other excellent effects of the film. , including multiple groups of double bond functional monomers and hydrophobic macromolecular silicon-containing double bond polymerizable monomers, the special functional monomers account for the total amount of anionic emulsifiers, acrylate monomers, special functional monomers and molecular weight regulators 10-25% of the amount (although the hardness of the functional monomer is high, it still needs a high density to improve the hardness and the contact angle effect of the surface after film formation, so as to achieve a good super-hydrophobic effect. If used If the amount of functional monomer is less than this amount, it is easy to cause insufficient hardness after film formation, which makes the coating easy to wear.

Specifically, the molecular weight regulator is thiol and its derivatives or primary, secondary and tertiary thiols, thiol esters and thiol ethers with 5 to 14 carbon atoms, and the molecular weight regulator accounts for anionic emulsifier, acrylic acid 0.15-0.60% of the total amount of ester monomers, special functional monomers and molecular weight regulators. Selecting molecular regulators can well control the molecular weight of the resin, ensure that the relative molecular weight of the obtained resin is relatively moderate, and ensure that the obtained resin is more Uniformity, if the proportion of use is small, the control of the resin is not obvious, and if the proportion of use is large, the molecular weight control is too low, and too low molecular weight will easily lead to insufficient strength and compactness of the coating, thus comprehensive performance will also be affected.

Specifically, the initiator is one of sodium persulfate, ammonium persulfate, and potassium persulfate, and the initiator accounts for 5% of the total amount of anionic emulsifier, acrylate monomer, special functional monomer and molecular weight regulator. 0.1～0.6%.

Specifically, it includes the following steps:

S100, preparing a pre-emulsion;

S200, preparing seed emulsion;

S300, emulsification reaction;

S400, post-elimination processing;

S500, cooling treatment.

Specifically, the emulsification reaction in the step S300 is to add the remaining pre-emulsion and the initiator solution dropwise to the prepared seed emulsion, the dropping time is 2-3 hours, and the dropping temperature is 80-90° C. When the remaining pre-emulsion is The resin crosslinking agent is added when the liquid and initiator solution are added dropwise to one third. If the resin crosslinking agent used is added early, the latex particles are unstable during the initial reaction, and the degree of crosslinking is large, it is easy to slag. If the addition time is too late, it will not have a good cross-linking effect. According to the repeated test results in the laboratory, it is finally found that the overall improvement effect is more obvious in one third of the time. The resin cross-linking agent is Ethylene glycol dimethacrylate.

Specifically, the post-elimination treatment in step S400 is specifically to cool the solution after the emulsification reaction to 60° C., add an oxidant and a reducing agent and keep the temperature for 1 hour, the oxidant is tert-butyl hydroperoxide, and the reducing agent is FF6M.

Example 1

To prepare the emulsion, weigh 160 g of deionized water, 10 g of emulsifier K12 and environmentally friendly non-ionic emulsifier, stir for 15 minutes, add 250.4 g of styrene, methyl methyl ester, 132.3 g of butyl acrylate and isooctyl acrylate, and 50 g of methyl acrylate. Isobornyl acrylate, 14.2 g of special functional monomers, and 0.5 g of dodecyl mercaptan were stirred for 30 minutes to obtain a pre-emulsion.

To prepare the bottom material of the kettle, weigh 360g of deionized water, 8g of emulsifier K12 and non-ionic emulsifier and stir for 10 minutes.

When the temperature in the kettle rises to 85°C, add 5% pre-emulsion to the kettle, add 5g of ammonium persulfate solution (dissolve 0.25g of ammonium persulfate with 5g of water), and react for 10 minutes to obtain a seed emulsion.

Add the remaining emulsion and 70g of ammonium persulfate solution (dissolve 0.4g of ammonium persulfate with 70g of water) dropwise for 2 hours, add resin multi-double bond cross-linking monomer when it is added dropwise to 1/4 of the emulsion, and react The temperature is controlled at 85-90°C.

After the dropwise addition was completed, the reaction was incubated for 1 hour. Cool down to 60 ℃, add tert-butyl hydroperoxide aqueous solution (5g water dissolves 0.18g tert-butyl hydroperoxide), interval 10 minutes, add FF6M aqueous solution (10g water dissolves 0.09g FF6M), add and keep warm for 1 hour.

After the heat preservation is completed, the temperature is lowered to below 40° C., and the material is filtered with a 200-mesh filter cloth to obtain a superhydrophobic acrylic emulsion with a solid content of 46-48%, a pH of 7-9, and a viscosity of less than 100 mPa.s.

For the acrylic resin prepared in this example, the pH was adjusted with ammonia; the test added a certain amount of film-forming aid to the resin emulsion, and brushed it on the surface of the paint to test the dripping test. The stain effect can meet the requirements of the national standard, and the water resistance of the tested emulsion is excellent.

It is obtained through emulsion polymerization by selecting environmentally friendly emulsifiers, special functional monomers, acrylate monomers, molecular weight regulators and cross-linking agents of late resin molecules, the preparation process is simple, and the product is green and environmentally friendly. Compared with the common one-component acrylic resin, the acrylic resin prepared by the present invention greatly changes the surface tension and hardness of the resin after film formation by introducing special functional monomers, molecular weight adjustment and special technology, which is a good solution to the problem. At present, acrylic resin is not excellent in water resistance, but it provides a good surface treatment of dripping water and beading, as well as excellent water resistance.

The above-mentioned embodiment only expresses a certain embodiment of the present invention, and its description is more specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention; it should be pointed out that for those of ordinary skill in the art Said that, on the premise of not departing from the concept of the present invention, several modifications and improvements can be made, which all belong to the protection scope of the present invention; therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

A preparation method of super-hydrophobic acrylic emulsion, which is characterized in that: 3-5% of the total monomer content of emulsifier and water are fully stirred and mixed for 15-30 minutes, and then acrylate monomers, special functional monomers, molecular weights are added. The regulator is stirred and emulsified for 30-60 minutes to obtain a pre-emulsion; the 3-5% emulsifier and water of the total monomer are stirred evenly, and then 3% of the pre-emulsion is added, and 60% of the initiator solution is added dropwise at the same time. Reaction 7 After 15 minutes, the seed emulsion was prepared; the remaining pre-emulsion and the initiator solution were added dropwise to the seed emulsion, and the temperature was kept at 60°C, and the temperature was lowered to 60°C. Hereinafter, the superhydrophobic acrylic emulsion is obtained by filtering and discharging the material.
The method for preparing a super-hydrophobic acrylic emulsion according to claim 1, wherein the emulsifier is an anionic emulsifier, and the anionic emulsifier is sodium dodecyl sulfate, dodecylbenzenesulfonic acid At least one of sodium, ethoxylated alkyl sulfate sodium salt, alkyl ether sulfate sodium salt, and fatty alcohol ether sulfate sodium salt.
The method for preparing a super-hydrophobic acrylic emulsion according to claim 2, wherein the anionic emulsifier accounts for 2-2% of the total amount of the anionic emulsifier, acrylate monomers, special functional monomers and molecular weight regulators. 10%.
The preparation method of a kind of super-hydrophobic acrylic emulsion according to claim 1, is characterized in that: described acrylate monomer is

One or more of styrene, methyl methyl, methacrylic acid and acrylic acid;

or

One or both of butyl acrylate, isooctyl acrylate and methyl methacrylate;

Or silicon-containing functional monomers or special resin cross-linking monomers.
The method for preparing a super-hydrophobic acrylic emulsion according to claim 1, wherein the special functional monomer is isobornyl methacrylate, including multiple groups of double-bond functional monomers and hydrophobic macromolecules containing silicon Double bond polymerizable monomer, the special functional monomer accounts for 10-25% of the total amount of anionic emulsifier, acrylate monomer, special functional monomer and molecular weight regulator.
The preparation method of a kind of super-hydrophobic acrylic emulsion according to claim 1, it is characterized in that: described molecular weight regulator is mercaptan and its derivative or primary, secondary, tertiary mercaptan of 5～14 carbon atoms, sulfur For alcohol esters and thiol ethers, the molecular weight regulator accounts for 0.15-0.60% of the total amount of anionic emulsifiers, acrylate monomers, special functional monomers and molecular weight regulators.
The preparation method of a kind of super-hydrophobic acrylic emulsion according to claim 1, is characterized in that: described initiator is a kind of in sodium persulfate, ammonium persulfate, potassium persulfate, and described initiator accounts for anionic emulsifier , 0.1-0.6% of the total amount of acrylate monomers, special functional monomers and molecular weight regulators.
The preparation method of a kind of super-hydrophobic acrylic emulsion according to claim 1, is characterized in that, specifically comprises the steps:

S100, preparing a pre-emulsion;

S200, preparing seed emulsion;

S300, emulsification reaction;

S400, post-elimination processing;

S500, cooling treatment.
The method for preparing a super-hydrophobic acrylic emulsion according to claim 8, wherein the emulsification reaction in the step S300 is dropwise adding the remaining pre-emulsion and the initiator solution to the prepared seed emulsion, and the dropping time 2-3 hours, the dropping temperature is 80-90°C, when the remaining pre-emulsion and initiator solution are added dropwise by one third, add a resin cross-linking agent, the resin cross-linking agent is ethylene glycol dimethacrylate ester.
The method for preparing a super-hydrophobic acrylic emulsion according to claim 8, wherein the post-elimination treatment in the step S400 is specifically cooling the solution after the emulsification reaction to 60°C, adding an oxidizing agent and a reducing agent, and keeping the temperature For 1 hour, the oxidizing agent was tert-butyl hydroperoxide, and the reducing agent was FF6M.