CN114349908B

CN114349908B - Preparation method of inverse emulsion, thickener and emulsifier

Info

Publication number: CN114349908B
Application number: CN202210070261.5A
Authority: CN
Inventors: 王晓; 马吉全; 刘斌; 刘前广; 刘照; 刘伟杰; 纪学顺; 孙家宽; 李棒棒
Original assignee: Wanhua Chemical Group Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd
Priority date: 2022-01-21
Filing date: 2022-01-21
Publication date: 2024-06-25
Anticipated expiration: 2042-01-21
Also published as: CN114349908A

Abstract

The invention discloses a preparation method of inverse emulsion, a thickener and an emulsifier. The method comprises the following steps: a. dissolving hydrophilic nonionic monomer, acidic monomer and/or salt, crosslinking agent and chelating agent in water, and regulating pH to obtain first aqueous solution; b. dissolving a hydrophilic nonionic monomer and a crosslinking agent in water to obtain a second aqueous solution; c. mixing the oil phase and the water-in-oil emulsifier, and cooling to 5-15 ℃; d. c, dropwise adding a first aqueous solution into the product of the step c to form a water-in-oil system, adding an oxidant at one time and deoxidizing, then dropwise adding a reducing agent to initiate polymerization, and preserving heat after the polymerization is finished; e. and d, dropwise adding a second aqueous solution into the product obtained in the step d, adding an oxidant at one time, deoxidizing, dropwise adding a reducing agent for polymerization, preserving heat after polymerization, cooling, adding an oil-in-water emulsifier, filtering and discharging to obtain the inverse emulsion. The inverse emulsion has excellent thickening performance and emulsifying performance, and can be used in the nursing application fields of cosmetic cream and the like.

Description

Preparation method of inverse emulsion, thickener and emulsifier

Technical Field

The invention relates to a preparation method of inverse emulsion, and a thickener and an emulsifier.

Background

Thickeners used in the cosmetic field are used to thicken the aqueous phase, or cream-gel systems. In a cream-gel system, a certain amount of emulsifier is also added, especially when high levels of oil are added to the system. However, emulsifiers are generally low molecular weight substances that are less resistant to the skin than polymers. Therefore, there is a need to develop a polymer having both thickening and emulsifying functions. In the patent applications published so far, mention is made of inverse emulsions of 2-acrylamido-2-methylpropanesulfonic Acid (AMPS) and Acrylamide (AM) obtained under the crosslinking action of N, N-methylenebisacrylamide. Patent US 8668915 B2 discloses in detail the preparation process flow of such an inverse emulsion, the emulsion having a thickening and emulsifying function is obtained by inverse emulsion polymerization forming water-in-oil, but the long-term thermal storage stability of emulsion emulsification is not mentioned, and the thermal storage stability of emulsification is an index of important attention of customers for a thickening aid used in the daily chemical field.

In the prior art, US8668915B2, US7033600B1 and US8765822B2 disclose in detail the preparation process of the inverse emulsion, wherein the pH of the aqueous solution is repeatedly regulated by the US8668915B2, the process is complex, and the operation efficiency is low; US7033600B1 further defines only the type of oil phase and does not disclose in detail the emulsifying capacity of the emulsion; whereas US8765822B2 relies on the introduction of nonionic monomers to improve the salt tolerance of the product, a decrease in the proportion of ionic monomers would simultaneously sacrifice the thickening efficiency of the polymer. It is therefore highly necessary to develop products having excellent thickening properties and emulsifying ability.

Disclosure of Invention

In order to solve the problems, the invention relates to a preparation method and application of an inverse emulsion with thickening and/or emulsifying effects. The core-shell structure with 'soft inside and hard outside' prepared by the invention has strong charge density and hydrophilicity, and molecular chains can be rapidly opened in water through charge repulsion, thus achieving the purpose of thickening. Meanwhile, the shell layer has high crosslinking density, and the polymer microsphere keeps high strength to realize long-term heat storage stability when the grease is emulsified, so that the polymer microsphere can be widely but not exclusively used in cosmetics such as various cream and the like of nursing chemicals to realize the application characteristic of thickening and emulsifying.

In order to achieve the above object, the present invention provides the following technical solutions:

A method for preparing an inverse emulsion comprising the steps of:

a. dissolving hydrophilic nonionic monomer, acidic monomer and/or salt, crosslinking agent and chelating agent in water, and regulating pH to 4-7 to obtain first aqueous solution;

b. dissolving a hydrophilic nonionic monomer and a crosslinking agent in water to obtain a second aqueous solution;

c. Respectively adding the oil phase and the water-in-oil emulsifier into the bottom of the kettle, starting stirring, and cooling to 5-15 ℃;

d. C, dropwise adding a first aqueous solution into the product of the step c to form a water-in-oil system, adding an oxidant at one time and deoxidizing, then dropwise adding a reducing agent to initiate polymerization, and preserving heat after the polymerization is finished;

e. And d, dropwise adding a second aqueous solution into the product obtained in the step d, adding an oxidant at one time, deoxidizing, dropwise adding a reducing agent for further polymerization, preserving heat after polymerization, cooling to not more than 40 ℃, adding an oil-in-water emulsifier, filtering and discharging to obtain the inverse emulsion.

Preferably, the hydrophilic nonionic monomer in step a is selected from one or more of acrylamide, N-vinylpyrrolidone, methacrylamide.

Preferably, the acidic monomer and/or salt is selected from one or more of acrylic acid, acrylic acid salt, 2-acrylamide-2-methylpropanesulfonic acid, 2-acrylamide-2-methylpropanesulfonate, methacrylic acid salt.

Preferably, the cross-linking agent is selected from one or more of N, N-methylene bisacrylamide, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate.

Preferably, the chelating agent is selected from at least one of EDTA-2Na or EDTA-4 Na.

Preferably, the oil phase is selected from isoparaffins, cosmetic grade white oils, preferably isotridecyl.

Preferably, the water-in-oil emulsifier is selected from at least one of span 60, span 80, C16-18 unsaturated bishydroxyethyl amide (WITCAMIDE 511).

Preferably, the oxidant is at least one selected from sodium persulfate, potassium persulfate, hydrogen peroxide and tert-butyl hydroperoxide.

Preferably, the reducing agent is at least one selected from the group consisting of isoascorbic acid, sodium metabisulfite, sodium bisulphite and ferrous sulfate.

Preferably, the oil-in-water emulsifier is at least one selected from fatty alcohol polyoxyethylene ether and salts thereof (AEO-7, AEO-9), sodium dodecyl benzene sulfonate, sodium dodecyl sulfonate, tween 60 or 80.

As a preferred embodiment, the ratio of the total amount of monomers (by mass) in the first aqueous solution to the total amount of monomers in the second aqueous solution is 5 to 20:1, for example, can be selected as 5: 1. 8: 1. 10: 1. 15: 1. 18:1, etc., the feed ratio of the above monomers can realize the layer thickness of the core-shell. When the shell layer is too thick, the polymer chain can be seriously limited to be opened when the polymer chain is thickened in water due to high crosslinking density of the shell layer, the thickening efficiency is reduced, and when the shell layer is too thin, the support strength of the shell layer is insufficient, the thermal storage stability of emulsification is affected, the polymer is curled when being heated, and the effect of emulsifying the grease is poor.

As a preferred embodiment, the mass ratio of hydrophilic nonionic monomer, acidic monomer and/or salt and crosslinking agent in step a is 1-20:2-50:0.01-1.

As a preferred embodiment, the mass ratio of hydrophilic nonionic monomer to crosslinking agent in step b is 1-20:0.05-1.

As a preferred scheme, the water-in-oil emulsifier is used in an amount of 2-4.5% of the total mass of the inverse emulsion, and the oil-in-water emulsifier is used in an amount of 2.5-5% of the total mass of the inverse emulsion.

As a preferred scheme, in the preparation method, the oxidant in the step d accounts for 0.01-1% of the total mass of the monomer in the step a, and the reducing agent in the step d accounts for 0.02-2% of the total mass of the monomer in the step a.

As a preferred scheme, in the preparation method, the oxidant in the step e accounts for 0.05-1% of the total mass of the monomers in the step b, and the reducing agent in the step e accounts for 0.1-2% of the total mass of the monomers in the step b.

As a preferable scheme, the heat preservation temperature is 60-80 ℃ after the polymerization is finished, the heat preservation time after the polymerization is finished in the step d is 0.5-2h, and the heat preservation time after the polymerization is finished in the step e is 1-4h.

The core-shell emulsion prepared by the invention has the characteristics of soft inside and hard outside. Throughout the entire preparation process, hydrophilic monomers are employed, and the continuous phase of the emulsion is the oil phase, and is thus referred to as inverse emulsion polymerization. The polymer particles have a very strong hydrophilic nature. On the premise of presetting the pH value, the polymer chain segment can be rapidly expanded in water due to charge repulsion to form certain microgel particles, and the high crosslinking density of the shell can ensure that the microgel particles have enough strength and excellent performance in the aspect of emulsion heat storage stability.

Another aspect of the present invention is to provide a polyacrylamide inverse emulsion prepared by the above method.

It is another object of the present invention to provide the use of the polyacrylamide inverse emulsion prepared by the above method in personal care applications, such as thickeners and emulsifiers in cosmetics. Preferably in the field of skin or hair care products and the like.

The invention has the remarkable characteristics and advantages that polymer particles are subjected to regulation and control of the proportion of monomers and cross-linking agents by a stepwise inverse emulsion polymerization method to obtain a polymer core-shell structure with 'inner soft and outer hard', on one hand, water phase thickening can be realized through electrostatic repulsion by high charge density in the core, and on the other hand, the high cross-linking strength of the shell layer can ensure that the swelled polymer particles keep high strength, so that long-term emulsion heat storage stability is realized.

Detailed Description

So that the technical features and content of the present invention can be understood in detail, preferred embodiments of the present invention will be described in more detail below. While the preferred embodiments of the present invention have been described in the examples, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein.

< Source of raw materials >

Acrylamide (AM), jiangsu Changjiunong chemical industry;

2-acrylamide-2-methylpropanesulfonic Acid (AMPS), a shou hong creating environmental protection technology;

2-acrylamide-2-methylpropanesulfonic acid sodium aqueous solution (50%) (AMPS-Na), the longevity light is a new environmental protection technology;

trimethylolpropane triacrylate (TMPTA), triswood chemistry;

n, N-Methylenebisacrylamide (MBA), jinan Yunuo chemical;

Sodium Persulfate (SPS), a chinese medicine;

30% hydrogen peroxide (H ₂O₂), chinese medicine;

isoparaffin (Isopar M), exxon mobil;

erythorbic acid (IAA), zhengzhou tuoyang;

WITCAMIDE 511, nujo chemical;

AEO-7, basf.

Other reagents used in the examples and comparative examples of the present invention are conventional in the art, and will not be described here.

< Test method >

Preparation of aqueous thickening sample (1%)

99G deionized water was weighed into a 200mL straight bottle; stirring at 1000rpm by using an IKA R1303 stirring paddle; shaking the prepared emulsion sample uniformly, weighing 1g, and adding the solution under stirring; stirring is continued for 30 minutes at 1000 rpm; the resulting liquid was transferred with a spatula into a 100ml clear plastic bottle and stored at room temperature. The viscosity of the liquid was tested.

Viscosity test

Instrument: BROOKFIELD DV2T, annex: RV-6 rotor, sample: the emulsion water phase is thickened to a sample,

The steps are as follows: after initializing the instrument, the corresponding rotor was set at 5rpm.

Reading: the viscosity was unchanged at 1min and the final reading was recorded.

Preparation of aqueous thickening sample (2%)

The method was similar to the above except that 98g deionized water was weighed and 2g emulsion was weighed.

Emulsified sample preparation

15G of an oil (one of liquid paraffin and polydimethylsiloxane (100 cp)) was weighed into a 200mL straight bottle; 84g of deionized water was weighed in a straight bottle; stirring with an IKA R1303 stirring paddle at 1000 rpm; shaking the prepared sample uniformly, weighing 1g, and adding the solution under stirring; stirring is continued for 30 minutes at 1000 rpm; the resulting liquid was transferred with a spatula into a 100ml clear plastic bottle and stored at room temperature. The viscosity test method is the same as above.

And placing the emulsified sample in a constant temperature oven at 45 ℃ for one month, testing the viscosity again, and observing whether oil drops are separated out.

Example 1

1) 130G of AM, 220g of AMPS, 300g of AMPS-Na solution, 0.2g of MBA, 1g of EDTA-2Na and 180g of deionized water are mixed, and are neutralized by 50wt% of NaOH solution, and the pH is regulated to 5.5, so that a first aqueous solution is obtained;

2) Mixing 13g of AM, 0.05g of MBA and 15g of deionized water to obtain a second aqueous solution;

3) Mixing 300g Isopar M and 30g 511 emulsifier, and cooling to 5 ℃;

4) Dropwise adding the aqueous solution of 1) into the oil phase of 3) under stirring, adding 10g of 2% SPS aqueous solution at one time, and deoxidizing for 30min;

5) 20g of 2% IAA aqueous solution is dripped to initiate polymerization, the dripping time is 1h, and the temperature is further kept at 70 ℃ for 1h after dripping;

6) Dropwise adding the second aqueous solution into the system with the end of the reaction of 5), adding 2g of 2% SPS aqueous solution at one time according to the initiation mode, deoxidizing for 15min, dropwise adding 3g of 2% IAA aqueous solution for 10min, and further preserving heat at 70 ℃ for 1h;

7) Cooling to 30deg.C, slowly adding 40g AEO-7 for 15min, stirring for 15min, filtering, and discharging.

Examples 2 to 4

The procedure of example 1 was followed and the amounts of the relevant materials are shown in Table 1.

Example 5

The materials in the following process conditions are adopted according to the material consumption in the table 1:

the first aqueous solution in step 1) is adjusted to pH 7; controlling the temperature of the oil phase to 15 ℃ in the step 3), wherein the dripping time of the reducing agent initiated by the first aqueous solution in the step 5) is 2 hours; the temperature of the cooling and AEO-7 in the step 7) is 40 ℃; the other conditions were the same as in example 1.

Example 6

the first aqueous solution in step 1) is adjusted to a pH of 4; the heat preservation temperature at the end of the polymerization of the first aqueous solution in the step 5) is 80 ℃ and the heat preservation time is 0.5h; the time for adding AEO-7 after the reaction in the step 7) is 30min; the other conditions were the same as in example 1.

Comparative example 1

2) Mixing 300g Isopar M and 30g 511 emulsifier, and cooling to 5 ℃;

3) Dropwise adding the aqueous solution of 1) into the oil phase of 2) under stirring, adding 10g of 2% SPS aqueous solution at one time, and deoxidizing for 30min;

4) 20g of 2% IAA aqueous solution is dripped to initiate polymerization, the dripping time is 1h, and the temperature is further kept at 70 ℃ for 1h after dripping;

5) Cooling to 30deg.C, slowly adding 40g AEO-7 for 15min, stirring for 15min, filtering, and discharging.

Comparative example 2

The amount of the crosslinking agent of the first aqueous solution in step 1) is 0.3g; the amount of the second aqueous solution cross-linking agent in the step 2) is 0.02g, and the rest conditions are the same as in the example 1, so that the core-shell structure with hard inside and soft outside is formed.

Comparative example 3

AEO-7 was added in step 7) as a one-time quick addition, the rest of the conditions being the same as in example 1.

Comparative example 4

The mass ratio of the first aqueous solution to the second aqueous solution is 4:1, the amounts of the relevant materials are shown in the following table, and the rest of the conditions are the same as in example 1.

Comparative example 5

The mass ratio of the first aqueous solution to the second aqueous solution is 25:1, the amounts of the relevant materials are shown in the following table, and the rest of the conditions are the same as in example 1.

Table 1 amounts of materials used in examples and comparative examples

The polymer emulsions of each of the examples and comparative examples prepared by the above method were subjected to thickening and emulsification tests according to the aforementioned methods, and the related data are shown in table 3.

TABLE 3 thickening and emulsifying test results

As can be seen from the data of each example and comparative example in table 3, the emulsion has excellent thickening performance on the one hand and excellent thermal storage stability of the emulsified oil and fat on the other hand due to the core-shell structure of "soft inside and hard outside" formed by the addition of the segment monomers and the adjustment of the crosslinking agent. As can be seen from comparison of comparative example 1 with the examples, if no aqueous two-stage monomer solution is added, the emulsion obtained by conventional inverse emulsion polymerization, although having superior thickening properties, lacks the "shell" which results in insufficient strength of the polymer particles during swelling, directly affects the thermal storage stability of the emulsion, and the polymer microgel shape is not maintained during heating, resulting in emulsion failure and delamination. Similarly, the data of comparative example 2 further demonstrate that if a core-shell structure of "inside hard-out soft" is formed, on the one hand, the core thickened by charge repulsion is severely inhibited, resulting in insufficient thickening performance, and on the other hand, the shell is too soft, and the heat storage stability of emulsification is also problematic. In contrast, in comparative example 3, if the oil-in-water emulsifier is added too quickly, the polymer particles undergo too fast phase inversion, resulting in demulsification and failure to obtain a normal emulsion. As can be seen from comparison 4 and comparison 5, when the shell layer is too thick, electrostatic repulsive force is affected, and thus thickening efficiency is affected; when the shell layer is too thin, the polymer particles are heated to shrink, which affects emulsion stability.

The foregoing description of embodiments of the invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the spirit of the invention.

Claims

1. A method for preparing an inverse emulsion comprising the steps of:

e. Dropwise adding a second aqueous solution into the product obtained in the step d, adding an oxidant at one time, deoxidizing, dropwise adding a reducing agent for further polymerization, preserving heat after polymerization, cooling to not more than 40 ℃, adding an oil-in-water emulsifier, filtering and discharging to obtain inverse emulsion;

The ratio of the total mass of the monomers in the first aqueous solution to the total mass of the monomers in the second aqueous solution is 5-20:1, a step of;

The mass ratio of the hydrophilic nonionic monomer, the acidic monomer and/or the salt to the cross-linking agent in the step a is 1-20:2-50:0.01-1;

The mass ratio of the hydrophilic nonionic monomer to the crosslinking agent in the step b is 1-20:0.05-1.

2. The method according to claim 1, wherein the hydrophilic nonionic monomer in step a is selected from one or more of acrylamide, N-vinyl pyrrolidone, methacrylamide; and/or the acidic monomer and/or salt is selected from one or more of acrylic acid, acrylic acid salt, 2-acrylamide-2-methylpropanesulfonic acid, 2-acrylamide-2-methylpropanesulfonate, methacrylic acid and methacrylic acid salt.

3. The method of claim 1, wherein the cross-linking agent is selected from one or more of N, N-methylenebisacrylamide, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate.

4. The method of claim 1, wherein the chelating agent is selected from at least one of EDTA-2Na or EDTA-4 Na; and/or the oil phase is selected from isoparaffins, cosmetic grade white oils.

5. The method of claim 1, wherein the water-in-oil emulsifier is selected from at least one of span60, span 80, C16-18 unsaturated bishydroxyethyl amide; and/or the oil-in-water emulsifier is at least one selected from fatty alcohol polyoxyethylene ether and salts thereof, sodium dodecyl benzene sulfonate, sodium dodecyl sulfonate, tween 60 or 80.

6. The method of claim 1, wherein the water-in-oil emulsifier is present in an amount of 2-4.5% by weight of the total mass of the inverse emulsion and the oil-in-water emulsifier is present in an amount of 2.5-5% by weight of the total mass of the inverse emulsion.

7. The method of claim 1, wherein the oil phase is isotridecyl.

8. A thickener comprising the inverse emulsion prepared by the method of any one of claims 1-7.

9. An emulsifier comprising an inverse emulsion prepared by the method of any one of claims 1-7.