阅读说明：本技术 一种具有宽温域和梯度结构叔丙乳液的制备方法 (Preparation method of tertiary acrylic emulsion with wide temperature range and gradient structure ) 是由 肖继君 田佳 白璐 李双 于 2021-10-13 设计创作，主要内容包括：本发明提供了一种具有宽温域和梯度结构叔丙乳液的制备方法,该方法以丙烯酸酯类单体、丙烯酸类单体和叔碳酸乙烯酯类单体为反应单体,以反应性乳化剂为乳化剂,通过控制加料方式,制备得到具有宽温域和梯度结构的叔丙乳液。本发明制备得到的叔丙乳液粒子形态为梯度渐变,形成多层异型结构的乳胶粒,拓宽了乳液玻璃化转变温度,改善了聚合物热粘冷脆的缺点,作为涂料使用时既具有一定硬度又不会导致乳胶膜发黏。同时还有效地提高了乳液的稳定性、乳胶膜的耐水性和耐腐蚀性。(The invention provides a preparation method of a tertiary acrylic emulsion with a wide temperature range and a gradient structure. The tertiary propyl emulsion particles prepared by the invention are gradient and gradual-changing in shape, form multi-layer emulsion particles with special-shaped structures, broaden the glass transition temperature of the emulsion, improve the defects of hot adhesion and cold brittleness of polymers, and have certain hardness and can not cause the adhesion of emulsion films when being used as a coating. Meanwhile, the stability of the emulsion and the water resistance and corrosion resistance of the emulsion film are effectively improved.)

1. A preparation method of tertiary acrylic emulsion with wide temperature range and gradient structure is characterized by comprising the following steps:

(1) adding water, a part of reactive emulsifier, a part of initiator and a part of buffer agent into a reaction bottle; stirring, and raising the temperature of a reaction system to 76-78 ℃;

(2) dividing a reaction monomer and the residual reactive emulsifier into two parts, wherein each part comprises the reactive emulsifier and the reaction monomer, adding the two parts of materials into a far-end feeding bottle and a near-end feeding bottle respectively, and stirring to uniformly mix the monomers in the two bottles, wherein the reaction monomer comprises an acrylate monomer, an acrylic monomer and a vinyl versatate monomer; the amount of the vinyl versatate monomers in the near-end feeding bottle is greater than that in the far-end feeding bottle, the amount of the acrylic monomers and the acrylic ester monomers with the glass transition temperature of greater than 0 ℃ in the near-end feeding bottle is greater than that of the acrylic monomers and the acrylic ester monomers with the glass transition temperature of greater than 0 ℃ in the far-end feeding bottle, and the amount of the acrylic ester monomers with the glass transition temperature of less than 0 ℃ in the near-end feeding bottle is less than that of the acrylic ester monomers with the glass transition temperature of less than 0 ℃ in the far-end feeding bottle;

the far-end feeding bottle is provided with a far-end delivery pump, and the near-end feeding bottle is provided with a near-end delivery pump;

(3) setting the speed ratio of a near-end delivery pump to a far-end delivery pump to be 1.9-2.1: 1, simultaneously starting the two delivery pumps, enabling a mixed monomer in a far-end feeding bottle to enter the near-end feeding bottle through the far-end delivery pump, mixing with the monomer in the near-end feeding bottle, and then entering a reaction bottle through the near-end delivery pump for reaction; when blue light appears in the reaction bottle, suspending the two delivery pumps and preserving heat;

(4) after the heat preservation is finished, heating to 80-82 ℃, opening two delivery pumps, simultaneously dripping the rest of aqueous solution of the initiator and the buffer agent into the reaction bottle, after the monomer is dripped for 30min, dripping the aqueous solution of the cross-linking monomer, and after the monomer, the cross-linking monomer, the initiator and the aqueous solution of the buffer agent in the feeding bottle are dripped simultaneously, preserving the heat and reacting;

(5) and after the heat preservation reaction is finished, cooling to 74-76 ℃, sequentially adding an oxidant and a reducing agent into the system, preserving heat, then cooling to 30 ℃, adjusting the pH value to about 7-8, adding a cross-linking agent aqueous solution, and filtering with a 300-mesh sieve to obtain the tertiary propyl emulsion.

2. The method for preparing tertiary propyl emulsion with wide temperature range and gradient structure as claimed in claim 1, wherein the reactive emulsifier used in step (1) accounts for 30% of the total amount thereof, and the buffer and initiator account for 50% of the total amount thereof.

3. The method for preparing tertiary propyl emulsion with wide temperature range and gradient structure as claimed in claim 1, wherein in step (1), the reactive emulsifier is one or two of SR-10 and ER-10; the initiator is one of ammonium persulfate, potassium persulfate or sodium persulfate; the buffer is one of sodium bicarbonate or sodium hydrogen phosphate.

4. The method for preparing the tertiary propyl emulsion with wide temperature range and gradient structure as claimed in claim 1, wherein in step (2), the acrylate monomer is one or more of methyl methacrylate, butyl acrylate or isooctyl acrylate; the vinyl versatate monomer is any one or two of Shivnea 9, Shivnea 10 or Shivnea 11; the acrylic monomer is methacrylic acid.

5. The method for preparing a tertiary-propyl emulsion with wide temperature range and gradient structure as claimed in claim 1, wherein in step (4), the crosslinking monomer is diacetone acrylamide (DAAM).

6. The method for preparing a tertiary propyl emulsion with a wide temperature range and a gradient structure as claimed in claim 1, wherein in step (5), the oxidizing agent is tert-butyl hydroperoxide and the reducing agent is sodium formaldehyde sulfoxylate, and the ratio of the oxidizing agent to the reducing agent is 1: 1.

7. The method for preparing tertiary propyl emulsion with wide temperature range and gradient structure as claimed in claim 1, wherein in step (5), the cross-linking agent is adipic Acid Dihydrazide (ADH), and the mass ratio of the cross-linking monomer to the cross-linking agent is 2.0: 1.0.

Technical Field

The invention relates to a preparation method of tertiary propyl emulsion, in particular to a preparation method of tertiary propyl emulsion with wide temperature range and gradient structure.

Background

The tert-propyl emulsion synthesized by using methyl methacrylate, butyl acrylate and vinyl versatate as main monomers and methacrylic acid, glycidyl methacrylate and methacrylamidopropyl trimethoxy silane as crosslinking monomers has the characteristics of excellent weather resistance, adhesive force, water resistance and the like, is a preferred emulsion of water-based paint, and is widely applied to the fields of buildings and water-based industrial anticorrosive paint.

When the tertiary acrylic emulsion prepared by the traditional method is used as a coating, the glass transition temperature (Tg) and the Minimum Film Forming Temperature (MFFT) are in great contradiction, when the MFFT is higher, the film forming is difficult, the construction is difficult, and the emulsion film is easy to become brittle at low temperature; when the MFFT is low, a film can be formed at room temperature, but it does not provide sufficient hardness to the latex film, and it is liable to be tacky at high temperature, affecting coating properties. When the coating is applied to a metal substrate, the aqueous solvent increases the density of water on the surface of the metal, accelerates the corrosion of the metal, and greatly limits the application in industry. Therefore, the research on the preparation process of the corrosion-resistant tertiary propyl emulsion with wide temperature range is of great significance.

Disclosure of Invention

The invention aims to provide a preparation method of a tertiary acrylic emulsion with a wide temperature range and a gradient structure, and aims to solve the problems of poor stability and corrosion resistance, hot-sticking and cold-brittleness and the like of the tertiary acrylic emulsion prepared by the conventional method.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a preparation method of tertiary acrylic emulsion with wide temperature range and gradient structure comprises the following steps:

(1) adding water, a part of reactive emulsifier, a part of initiator and a part of buffer agent into a reaction bottle; stirring, and raising the temperature of a reaction system to 76-78 ℃;

(2) dividing a reaction monomer and the residual reactive emulsifier into two parts, wherein each part comprises the reactive emulsifier and the reaction monomer, adding the two parts of materials into a far-end feeding bottle and a near-end feeding bottle respectively, and stirring to uniformly mix the monomers in the two bottles, wherein the reaction monomer comprises an acrylate monomer, an acrylic monomer and a vinyl versatate monomer; the amount of the vinyl versatate monomers in the near-end feeding bottle is greater than that in the far-end feeding bottle, the amount of the acrylic monomers and the acrylic ester monomers with the glass transition temperature of greater than 0 ℃ in the near-end feeding bottle is greater than that of the acrylic monomers and the acrylic ester monomers with the glass transition temperature of greater than 0 ℃ in the far-end feeding bottle, and the amount of the acrylic ester monomers with the glass transition temperature of less than 0 ℃ in the near-end feeding bottle is less than that of the acrylic ester monomers with the glass transition temperature of less than 0 ℃ in the far-end feeding bottle;

the far-end feeding bottle is provided with a far-end delivery pump, and the near-end feeding bottle is provided with a near-end delivery pump;

(3) setting the speed ratio of a near-end delivery pump to a far-end delivery pump to be 1.9-2.1: 1, simultaneously starting the two delivery pumps, enabling a mixed monomer in a far-end feeding bottle to enter the near-end feeding bottle through the far-end delivery pump, mixing with the monomer in the near-end feeding bottle, and then entering a reaction bottle through the near-end delivery pump for reaction; when blue light appears in the reaction bottle, suspending the two delivery pumps and preserving heat;

(4) after the heat preservation is finished, heating to 80-82 ℃, opening two delivery pumps, simultaneously dripping the rest of aqueous solution of the initiator and the buffer agent into the reaction bottle, after the monomer is dripped for 30min, dripping the aqueous solution of the cross-linking monomer, and after the monomer, the cross-linking monomer, the initiator and the aqueous solution of the buffer agent in the feeding bottle are dripped simultaneously, preserving the heat and reacting;

(5) and after the heat preservation reaction is finished, cooling to 74-76 ℃, adding an oxidant aqueous solution into the system, adding a reducing agent aqueous solution after 5 min, preserving heat, cooling to 30 ℃, adjusting the pH value to be about 7-8, adding a cross-linking agent aqueous solution, and filtering by a 300-mesh sieve to obtain the tertiary propyl emulsion.

The reactive emulsifier used in step (1) accounts for 30% of the total amount, and the buffer and the initiator account for 50% of the total amount. The reactive emulsifier is one or two of SR-10 and ER-10. The initiator is one of ammonium persulfate, potassium persulfate or sodium persulfate. The buffer is one of sodium bicarbonate or sodium hydrogen phosphate.

In the step (2), the acrylate monomer is one or more of methyl methacrylate, butyl acrylate or isooctyl acrylate; the acrylic monomer is methacrylic acid; the vinyl versatate monomer is one or two of Shivnea 9, Shivnea 10 or Shivnea 11.

In the step (4), the crosslinking monomer is diacetone acrylamide (DAAM).

In the step (5), the oxidant is tert-butyl hydroperoxide, the reducing agent is sodium formaldehyde sulfoxylate, and the ratio of the oxidant to the reducing agent is 1: 1; the cross-linking agent is adipic Acid Dihydrazide (ADH), and the mass ratio of the cross-linking monomer to the cross-linking agent is 2.0: 1.0.

The preparation method can regularly change the proportion of soft segment monomers and hard segment monomers in the polymerization process, so that the composition of polymer latex particles is regularly changed from inside to outside, the form of the prepared tert-acrylic emulsion particles is gradually changed in a gradient manner, and the latex particles with a multi-layer special-shaped structure are formed, thereby widening the glass transition temperature of the latex, improving the defects of hot sticking, cold brittleness and the like of the polymer, and having certain hardness and not causing the stickiness of the latex film when being used as a coating. Meanwhile, the stability of the emulsion and the water resistance and corrosion resistance of the emulsion film are effectively improved.

Drawings

FIG. 1 is a transmission electron microscope analysis spectrum of the emulsion prepared in example 1.

Detailed Description

In the following examples, various procedures and methods not described in detail are conventional methods well known in the art.

Sources and specifications of reagents used:

methyl methacrylate was purchased from Shijiazhu Dongguang Xuhua, Industrial grade;

butyl acrylate was purchased from Shijiazhuang east Guang Xu chemical plant, technical grade;

methacrylic acid was purchased from Shijiazhuang east Guang Xu chemical plant, technical grade;

vinyl versatate is purchased from Siyou Tech science and technology Limited, Hebei, at industrial level;

the reactive emulsifier SR-10 is available from Nanjing Benth sea commercial trade company, Industrial grade;

diacetone acrylamide is available from Shanxi Asia chemical industry Co., Ltd, technical grade;

adipic dihydrazide is available from sunshine der si ltd, technical grade;

sodium bicarbonate was purchased from Tianjin Yongda chemical reagents, Inc., technical grade;

potassium persulfate was purchased from Tianjin Yongda chemical reagents, Inc., at industrial level;

t-butyl hydroperoxide was purchased from Tianjin Yongda chemical reagents, Inc., technical grade;

sodium formaldehyde sulfoxylate was purchased from Tianjin Yongda chemical reagents, Inc., at industrial level.

Example 1:

(1) 70 g of deionized water, 0.75 g of a reactive emulsifier SR-10, 9.8g of an aqueous KPS solution (10 wt.%) and 9.5g of NaHCO₃The aqueous solution (10 wt%) was placed in a reaction flask equipped with a condenser, a thermometer and a stirrer, the temperature of the reaction system was raised to about 78 ℃, and the mixture was stirred at medium speed until the thermometer in the reaction flask reached the set temperature of 78 ℃.

0.78 g of the reactive emulsifiers SR-10 and 17.6 g of MMA, 1.2 g of MAA, 3.3 g of Shivnea 10 and 22.7 g of BA were put in a far-end addition flask, 0.97 g of the reactive emulsifiers SR-10 and 26.4 g of MMA, 0.8 g of MAA, 16.7 g of Shivnea 10 and 11.3 g of BA were put in a near-end addition flask, and stirred at a high speed for 30 minutes to uniformly mix the monomers in both flasks.

(2) And (3) setting the speed of the peristaltic pump at the far end to be 2.5 rpm and the speed of the peristaltic pump at the near end to be 5.1 rpm, simultaneously opening the two peristaltic pumps for 7.5 min, pausing the two peristaltic pumps, and keeping the temperature for 30 min. Then the temperature is raised to 80 ℃, two peristaltic pumps are opened, the dropping of the mixed monomer and the initiator/buffer aqueous solution is started, when the dropping is carried out for 30min, 13.8g of DAAM aqueous solution (15 wt%) is started, and all the materials are controlled to be dropped into the reaction bottle within 2.0 h-2.5 h.

After all the materials are added into the reaction bottle, the temperature is firstly preserved for 1 h, then the temperature is raised to 82 ℃, and the temperature is preserved for 1 h. The temperature was then lowered to 74 ℃ and 3.5g of aqueous tert-butyl hydroperoxide (15 wt%) were added and after 5 min 3.5g of aqueous sodium formaldehyde sulfoxylate (15 wt%) were added and the temperature was maintained for 30 min. After the heat preservation is finished, the temperature is reduced to 30 ℃, the pH value is adjusted to be about 7-8, 13.4g of ADH aqueous solution (12 wt%) is added, and the mixture is filtered by a 300-mesh sieve to obtain the tertiary propyl emulsion.

Comparative example 1

The difference from the embodiment 1 is that: shivnea 10 was not added to the polymerization system.

The rest of the procedure was the same as in example 1.

Comparative example 2

The difference from the embodiment 1 is that: the emulsifier adopts common emulsifier sodium dodecyl diphenyl ether Disulfonate (DSB).

The rest of the procedure was the same as in example 1.

Comparative example 3

The difference from the embodiment 1 is that: the polymerization method adopts the traditional emulsion polymerization, and the specific implementation method is as follows:

s1, putting 44 g of MMA, 2 g of MAA, 20 g of Shivnea 10, 34 g of BA, 17.255g of aqueous solution (12.5 wt%) of reactive emulsifier SR-10 and 17.75 g of deionized water into a 500 ml feeding bottle, and stirring at high speed for 30min until no layering occurs to obtain a pre-emulsion. 51 g of deionized water, 1.86 g of KPS (5 wt.%), and 1.833 g of NaHCO₃(3.5 wt%) of the aqueous solution and 3g of a reactive emulsifier SR-10 aqueous solution (12.5 wt%) were placed in a reaction flask equipped with a mechanical stirrer, a thermometer and a condenser, the temperature was raised to 78 ℃ at a low speed, and then 15% of the pre-emulsion was added to the reaction flask, and blue light appeared, and the temperature was maintained for 30min to obtain a seed emulsion.

S2, after the heat preservation is finished, raising the temperature to 80 ℃, starting to dropwise add the residual pre-emulsion and the initiator buffer aqueous solution, adding 13.8g of DAAM aqueous solution (15 wt%) after 1.5 h, controlling the dropwise adding time to be 2.0 h-2.5 h, after the dropwise adding is finished, preserving the heat for 1 h, then raising the temperature to 82 ℃, and preserving the heat for 1 h. After the heat preservation is finished, the temperature is reduced to 74 ℃, 1.7g of tert-butyl hydrogen peroxide aqueous solution (3 wt%) is added, 1.7g of sodium formaldehyde sulfoxylate aqueous solution (3 wt%) is added after 5 min, and the heat preservation is carried out for 30 min. After the heat preservation is finished, the temperature is reduced to 30 ℃, the pH value is adjusted to be about 7-8, 7.5g of ADH aqueous solution (20 wt%) is added, and the mixture is filtered by a 300-mesh sieve to obtain the tertiary propyl emulsion.

Comparative example 4

The difference from the embodiment is that: shivnea 10 was not added, the emulsifier was sodium dodecyl diphenyl oxide disulfonate as a common emulsifier, and the polymerization method was a conventional emulsion polymerization, as shown in comparative example 3.

And (3) performance detection:

(1) the emulsion obtained in example 1 was diluted 100 times, dyed with phosphotungstic acid, naturally dried on a copper mesh, and tested by a transmission electron microscope, and the test results are shown in fig. 1. From FIG. 1, it can be seen that the color of the particles of example 1 gradually becomes lighter from inside to outside and the size of the latex particles is uniform, which indicates that the example of the present application obtains the emulsion with a gradient structure.

(2) The emulsions prepared in example 1 and comparative examples 1 to 4 were tested for stability.

Ca²⁺Stability 5mL of the emulsion was placed in a test tube and 5% CaCl was added dropwise₂Observing the solution for the presence of CaCl consumed by the precipitation flocculation state₂The amounts of (A) and (B) are shown in Table 1.

Diluting stability 5g of emulsion is taken, deionized water is added to dilute until the solid content is about 5%, the mixture is uniformly mixed and stands for 72 h at room temperature, the state of the emulsion is observed, and the test results are shown in table 1.

The Zeta potential was measured using a Z-300S laser particle size analyzer with water as the solvent to dilute the emulsion 100 times, and the test results are shown in Table 1.

(3) The latex films obtained in example 1 and comparative examples 1 to 4 were measured by HSC-1 type differential scanning calorimeter in the presence of N₂The latex film was tested for glass transition temperature (Tg) in an atmosphere with a scanning temperature range of-40 deg.C to 120 deg.C and a heating rate of 20 deg.C/min, the test results are shown in Table 1.

TABLE 1

As can be seen from Table 1, the product of example 1The resulting emulsion has excellent stability and a wide glass transition temperature range (i.e., a wide temperature range). While Ca of the emulsions prepared in comparative examples 1 and 3²⁺The stability is poor, and the Zeta potential is less than 50 mV, which shows that the emulsion stability of the comparative example 1 and the emulsion stability of the comparative example 3 are general. Ca of emulsions prepared in comparative examples 2 and 4²⁺The stability is extremely poor, and the Zeta potential is less than 40 mV, which indicates that the emulsion stability of comparative example 2 and comparative example 4 is poor.

Comparative examples 1 and 2 have a glass transition temperature range, but the range is narrow, and has a large difference from the wide temperature range of example 1; while comparative examples 3 and 4 each had only one glass transition temperature; it is shown that none of comparative examples 1 to 4 meet the requirements of the present application for a wide temperature range.

(4) EIS measurements were made on the emulsions prepared in example 1 and comparative examples 1-4 in 3.5% NaCl aqueous solution using a three-electrode system in which the working electrode was coated with epoxy to expose only 0.07068 cm²The cross section area is that a saturated calomel electrode is used as a reference electrode, a platinum electrode is used as a counter electrode, and the test frequency range is 10^-2To 10⁵Hz, amplitude of 20 mV, test results are shown in Table 2.

The emulsions prepared in example 1 and comparative examples 1 to 4 were subjected to a potentiometric polarization test in a 3.5% NaCl solution using a three-electrode system, a platinum electrode as a counter electrode, a saturated calomel electrode as a reference electrode, Q235 steel as a working electrode, a scanning rate of 2 mV/s, and a test voltage of Ecorr. + -. 1V, and the test results are shown in Table 2.

TABLE 2

As can be seen from Table 2, the impedance value of example 1 is 1.149X 10⁷Ω·cm²The self-etching voltage is-0.343V, and the self-etching current density is 1.59X 10^-8 A/cm². The emulsion prepared in the embodiment of the application has excellent corrosion resistance. While comparative examples 1 to 4 all had impedance values of less than 10⁵ Ω·cm²Self-etching voltageAre all smaller than example 1, and the self-etching current density is much greater than example 1. It is shown that the corrosion resistance of the emulsions of comparative examples 1 to 4 is significantly lower than that of example 1.