RU2836900C1 - Surfactant for aluminium pastes and method for production thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a surfactant used in the production of aluminium pastes in the field of powder metallurgy. the surfactant for producing aluminium pastes is a product of reaction of polyphosphoric acid with ethoxylated synthetic higher fatty alcohols, oxyethylated alkylphenols and triethylene glycol, with the following ratio of components, wt.%: ethoxylated synthetic higher fatty alcohols 60-67, polyphosphoric acid 14-17, oxyethylated alkylphenols 9-16, triethylene glycol 10-15. Invention also relates to a method of producing a surfactant.

EFFECT: development of a method for synthesis of a multicomponent surfactant, which provides: delayed onset of gas release reaction in lime mortar, wettability of aluminium particles in water, optimum level of inhibiting effect on aluminium particles, changing rheological properties of aerated concrete mixtures, namely reducing water separation and stratification of the concrete mixture, increasing gas retention capacity.

6 cl, 2 tbl, 5 ex

Description

Field of technology to which the invention relates

The present invention relates to a method for producing a multicomponent surfactant (hereinafter referred to as SAS) used for the production of aluminum pastes containing diethylene glycol in the field of powder metallurgy.

State of the art

A method is known for producing aqueous aluminum paste (RU patent No. 2134665, C04B22/04, published on 20.08.1999), which is flaky aluminum particles obtained by grinding powder in ball mills with the addition of 0.5 to 4% (by weight of aluminum) stearin.

The main disadvantage of such powder is its hydrophobicity - non-wetting of aluminum particles covered with stearin by water. Hydrophilic aluminum powders and aluminum pastes have been developed to solve this problem.

Aluminum pastes used for the production of cellular concrete are characterized by wettability in water and have a delayed onset of the gas evolution reaction in lime mortar.

Currently, to ensure these properties, the formulation of aluminum pastes includes a special surfactant, which is introduced into the product during the grinding process at the stage of production of hydrophilic aluminum powders or in the mixer at the stage of mixing hydrophobic aluminum powder with a solvent (diethylene glycol).

It is known to use phosphorus esters of fatty alcohols as surfactants in the preparation of aqueous aluminum pastes for aerated concrete and water-based pigment pastes, in which phosphorus esters serve both to wet the aluminum particles and to inhibit the process of interaction of aluminum particles with water (US patent No. 4,419,134, B22F1/00, C04B22/04, C04B24/00; C04B28/02, C04B38/02, C09C1/00, C09C1/62, C09C3/00, C09C3/08, C09D17/00, published 06.12.1983).

Commercial production of phosphoric acid esters is based on 2 main methods:

1. Interaction of phosphorus pentoxide (in the form of a symmetrical dimeric oxide structure) with the corresponding ethoxylated synthetic higher fatty alcohols:

P ₄ O ₁₀ + 6ROH → 2RH ₂ PO ₄ + 2R ₂ HPO ₄ (1)

2. Interaction of polyphosphoric acids (using triphosphoric acid as an example) with the corresponding ethoxylated synthetic higher fatty alcohols:

H ₅ P ₃ O ₁₀ + 2ROH → 2RH ₂ PO ₄ + H ₃ PO ₄ (2)

H ₅ P ₃ O ₁₀ + 2ROH → R ₂ HPO ₄ + 2H ₃ PO ₄ (3)

Modern commercially available phosphorus esters are effective emulsifiers for many applications, but they are not suitable for the production of diethylene glycol-based aluminum pastes used as blowing agents. This is due to one or more of the following reasons:

- weak wetting ability in relation to hydrophobic aluminum powders;

- absence of delay in the onset of the gas evolution reaction of aluminum pastes in lime mortar produced using these surfactants;

- absence of changes in the rheological properties of aerated concrete mixtures produced on the basis of aluminum pastes containing these surfactants.

In addition, commercially available phosphoric esters do not ensure the preservation of the quality characteristics of aluminum pastes during their storage for the entire required period (12 months). This is due to two reasons:

- lack of sufficient inhibitory effect of surfactants on aluminum particles. In this case, when adding solvent to hydrophilic aluminum powder, chemical interaction occurs between aluminum and solvent;

- the presence of excessive inhibitory effect of surfactants on aluminum particles. In this case, a significant slowdown in the reaction of gas emission of gas-forming agents in the lime solution is observed during their storage.

Methods for synthesizing alkyl phosphates as surface-active components of an alkaline-surfactant-polymer composition for enhancing oil recovery are known (N. Yu. Tretyakov, L. P. Panicheva, E. A. Turnaeva, S. S. Volkova, D. S. Adakhovsky, M. R. Matveev, I. N. Koltsov, A. A. Groman, Synthesis and study of the properties of alkyl phosphates as surface-active components of an alkaline-surfactant-polymer composition for enhancing oil recovery, News of universities. Applied chemistry and biotechnology, 2021, Vol. 11, No. 1). The use of such surfactants for the production of blowing agents is not possible due to their weak wetting ability with respect to hydrophobic aluminum powders.

A method for producing alkyl phosphorus surfactants using phosphoric anhydride is known, characterized in that in order to simplify the process technology, improve the quality and increase the cleaning action of the target products, alkyl benzenes are subjected to interaction with a sulfonating agent (patent SU No. 1154282, C07F9/09, published 07.05.1985). The disadvantage of these products is their strong foaming, which does not allow them to be used in recipes for the preparation of aluminum pastes.

A known method for producing dialkyl aryl phosphates is the reaction of unsubstituted or substituted phenol with phosphorus oxychloride in the presence of a catalyst - metal chloride upon heating, followed by esterification of the obtained aryl phosphoric acid dichloride with an excess of an aliphatic alcohol upon heating, characterized in that, in order to increase the productivity of the process, the aryl phosphoric acid dichloride is obtained in two stages by reacting phenol with phosphorus oxychloride in the first stage with the addition of phenol in the second stage (patent SU No. 1097630, C07F9/09, published 15.06.1984). The disadvantage of this method is the high toxicity of the raw materials and the lack of a delay in the onset of the gas evolution reaction of aluminum pastes in lime mortar produced using surfactants obtained by this method.

A method is known for producing surface-active esters of phosphoric acids by phosphorylation of higher hydroxyl-containing compounds with phosphoric anhydride, characterized in that, in order to improve the quality of the target products, the product of phosphorylation of a higher aliphatic alcohol with phosphoric anhydride is treated with a lower aliphatic alcohol or a lower carboxylic acid (patent SU No. 1047907, C07F9/09, published 15.10.1983). The disadvantage of this method is the use of phosphoric anhydride, which implies complete consumption of the component after opening the container. If it is necessary to produce small volumes of phosphoric esters, this method is inapplicable.

The closest in technical essence to the claimed technical solution is a method for synthesizing phosphorylated monoalkylphenol and its use as a hydrotrope (RU patent No. 2646611, C07F9/09, C11D3/36, published 06.03.2018), consisting in the synthesis of phosphorylated nonylphenols containing 4-9 oxyethylated units and two types of phosphoric acid residue, using polyphosphoric acid as a phosphorylating agent, characterized in that oxyethylated nonylphenols are phosphorylated with an appropriate degree of oxyethylation and a phosphorylation product is obtained containing 92-96 wt. % esters of phosphoric or polyphosphoric acids, and neutralization of the reaction mixture with an alkaline agent is not necessary.

The disadvantage of this method is the production of phosphorylated nonylphenols, which do not provide the required wettability of aluminum powders and do not affect the rheological properties of aerated concrete mixtures.

To solve the problem, it is necessary to produce a complex surfactant containing mono- and diesters of phosphoric acid and ethoxylated synthetic higher fatty alcohols, as well as auxiliary components that allow satisfying the list of all requirements imposed on the product.

Disclosure of the essence of the invention

The technical objective of the invention is to develop a method for synthesizing a multicomponent surfactant based on ethoxylated alkyl phosphate, used for the production of aluminum paste and providing:

- delay in the onset of the gas evolution reaction in lime mortar;

- wettability of aluminum particles in water;

- optimal level of inhibitory effect on aluminum particles;

- changing the rheological properties of aerated concrete mixtures, namely reducing water separation and stratification of the concrete mixture, increasing gas-holding capacity.

The technical task is achieved due to the fact that the surfactant for the production of aluminum pastes is a product of the interaction of polyphosphoric acid with ethoxylated synthetic higher fatty alcohols, oxyethylated alkylphenols and triethylene glycol, in the following ratio of components, wt. %:

ethoxylated synthetic higher fatty alcohols 60-67 polyphosphoric acid 14-17 oxyethylated alkylphenols 9-16 triethylene glycol 10-15,

in this case, the molar ratio of the components ethoxylated synthetic higher fatty alcohols: polyphosphoric acid is 3-5: 1.

The invention is supplemented by particular distinctive features that facilitate the achievement of the technical task. Alcohols of the following formula C _n H _2n+1 (C ₂ H ₄ O) _m CH ₂ CH ₂ OH (n=10-15; m=6-10) are used as ethoxylated synthetic fatty alcohols, and substances of the following chemical formula are used as oxyethylated alkylphenols:

where n = 7-12, R = C ₈ - C ₁₂ .

Another aspect of the invention is a method for producing the surfactant described above by mixing ethoxylated synthetic higher fatty alcohols with polyphosphoric acids in the first stage while maintaining a temperature of 70-100°C for 2-4 hours with vigorous stirring, followed by cooling the mixture to 40-50°C for 45-90 minutes, adding oxyethylated alkylphenols in the second stage while vigorously stirring the mixture for 50-80 minutes, followed by cooling the mixture to 18-25°C for 45-60 minutes, and adding triethylene glycol to the mixture in the last stage while vigorously stirring for 30-60 minutes.

At the first stage, a mixture of mono- and diesters of phosphoric acid and ethoxylated synthetic higher fatty alcohols, an excess of ethoxylated synthetic higher fatty alcohols that have not entered into the reaction, and orthophosphoric acid H ₃ PO ₄ in an amount not exceeding 5 wt.% are obtained.

Implementation of the invention

The technical solution relates to a method for synthesizing a multicomponent surfactant containing mono- and diesters of phosphoric acid and ethoxylated synthetic higher fatty alcohols, as well as auxiliary components that improve the properties of the product. The components included in the surfactant are responsible for performing independent functions and have a synergistic effect in relation to each other.

The production of complex surfactants is carried out through a multi-stage process, which includes the following stages.

Stage 1. Synthesis of mono- and diesters of phosphoric acid and ethoxylated synthetic higher fatty alcohols

The synthesis is carried out by the interaction of polyphosphoric acids with the corresponding ethoxylated synthetic higher fatty alcohols:

H ₆ P ₄ O ₁₃ + 3ROH → 3RH ₂ PO ₄ + H ₃ PO ₄ (4)

2H ₆ P ₄ O ₁₃ + 6 ROH → 3R ₂ HPO ₄ + 5H ₃ PO ₄ (5)

The starting materials for the synthesis of mono- and diesters of phosphoric acid and ethoxylated synthetic higher fatty alcohols are ethoxylated fatty alcohols C _n H _2n+1 (C ₂ H ₄ O) _m CH ₂ CH ₂ OH (n=10-15; m=6-10) 60-67 wt.% and polyphosphoric acid 14-17 wt.% (not less than 115 wt.%, in terms of orthophosphoric acid H ₃ PO ₄ ).

The synthesis is carried out at a stirring intensity of 200-250 rpm for 2-4 hours. The temperature regime is maintained in the range of 70-100°C. Before adding polyphosphoric acid, cooling is turned on to maintain the specified temperature of the reaction mixture. During the synthesis, the molar ratio of the components alcohol: polyphosphoric acid is 3-5: 1.

The products of the first stage of synthesis are:

- a mixture of mono and diesters of phosphoric acid and ethoxylated synthetic higher fatty alcohols;

- excess of ethoxylated synthetic higher fatty alcohols that have not reacted;

- orthophosphoric acid H ₃ PO ₄ in an amount not exceeding 5 wt.%, which is a by-product of the reaction.

Orthophosphoric acid is not removed from the mixture; neutralization of the intermediate product is not carried out.

The mixture is slowly cooled to a temperature of 40-50°C. The mixture is continuously stirred. The cooling time of the reaction mixture is 45-90 minutes.

The acid number, determined according to GOST 22386-77, is 160-250 mg KOH/g.

Stage 2. Partial synthesis of phosphorus esters of oxyethylated alkylphenols

9-16 wt. % of oxyethylated alkylphenols are added to the reaction mixture cooled to a temperature of 40-50°C at a stirring intensity of 200-250 rpm. The mixture is stirred for 50-80 minutes, during which time incomplete synthesis of phosphoric esters of oxyethylated alkylphenols occurs.

Substances of the following chemical formula are used as oxyethylated alkylphenols:

where n = 7-12, R = C ₈ - C ₁₂ .

After 50-80 minutes of intensive stirring at a temperature of 40-50°C, the mixture is slowly cooled to 18-25°C. Stirring of the mixture is not stopped. The cooling time of the reaction mixture is 45-60 minutes.

Step 3: Adding Triethylene Glycol

10-15 wt. % triethylene glycol is added to the reaction mixture cooled to 18-25°C at a stirring rate of 150-200 rpm. The mixture is stirred for 30-60 minutes, during which time the triethylene glycol is uniformly distributed among the other components of the complex surfactant.

The quality of the synthesized surfactant was assessed according to the parameters indicated in Table 1.

Table 1

No. Name of the indicator Method of analysis Norm 1 Appearance at temperature (20±2) °C Visual assessment Transparent liquid without mechanical inclusions, from light yellow to light brown in color 2 Hydrogen ion activity index of 1% aqueous solution, pH GOST 22567.5-93 ≤ 2.5 3 Acid value, mg KOH per 1 g of product GOST 22386-77 120-200 4 Wettability of hydrophobic aluminum powder containing 3 wt.% surfactant Visual assessment:
The method is based on the uniform, residue-free distribution of aluminum powder with water.
A sample of powder (2 g) is placed in a conical flask with a capacity of 250 cm ³ and filled with water in the amount of 100 cm ³ at room temperature. The contents of the flask are shaken for 1 minute, after which the resulting suspension is allowed to settle for 1 minute.
Aluminum powder is considered wettable if there is no suspension of lumps of unwetted powder (paste) or a continuous mirror film on the surface obtained within 1 minute. The presence of a thin film with breaks on the surface of the suspension is allowed. 100% 5 Volume of gas released in 2 minutes during the reaction of aluminum powder containing 3 wt.% surfactant with a solution of Ca(OH) ₂ , ml The method is based on determining the volume of hydrogen released during the interaction of aluminum powder (paste) with calcium hydroxide under standard specified conditions.
The analysis is carried out according to the method described in the “Quality Control Laboratory Tests” provided by WEHRHAHN to aerated concrete plants.
The technique is also described in the following source.
Bazhenov I.V. Automated complex for determining the main characteristics of aluminum blowing agents // 8th International scientific and practical conference "Experience in the production and use of autoclaved aerated concrete", Minsk, Mogilev, 11-13.06.2014. ≤ 18

Examples of implementation of the invention

The production of a complex surfactant containing mono- and diesters of phosphoric acid and ethoxylated synthetic higher fatty alcohols, as well as auxiliary components that improve the properties of the product, is illustrated by the following examples.

Mixing of the components of the mixture was carried out in a reactor equipped with a stirrer, a thermocouple and a thermostatic jacket. Additionally, the reaction mixture was bubbled with nitrogen to prevent unwanted chemical transformations and color changes in the resulting surfactant.

Example 1

350 g of a 4:1 molar mixture of ethoxylated synthetic higher fatty alcohols C ₁₀ -C ₁₅ with a degree of ethoxylation of 6-10 (60 wt.% of the total composition of the components) and polyphosphoric acid (15 wt.% of the total composition of the components) were loaded into a reactor. The reaction mixture was heated to 100 °C with stirring (stirring intensity 200-250 rpm) for 4 h. The product was cooled to 50 °C and 62 g of ethoxylated alkylphenol (13 wt.% of the total composition of the components, degree of ethoxylation 7-12, alkyl residue contains 8-12 carbon atoms) were added. The mixture was stirred for 50 minutes, after which it was cooled to a temperature of 25 °C and 56 g of triethylene glycol (12 wt.% of the total composition of the components) were added. The mixture was stirred for 30 minutes.

The acid number of the product was 148 mg KOH/1 g of product, the hydrogen ion activity index of 1% aqueous solution was 1.8. The product was a viscous transparent liquid of dark yellow color.

Example 2

350 g of a 3:1 molar mixture of ethoxylated synthetic higher fatty alcohols C ₁₀ -C ₁₅ with a degree of ethoxylation of 6-10 (51 wt.% of the total composition of the components) and polyphosphoric acid (17 wt.% of the total composition of the components) were loaded into a reactor. The reaction mixture was heated to 70 °C with stirring (stirring intensity 200-250 rpm) for 2 h. The product was cooled to 40 °C and 88 g of ethoxylated alkylphenol (17 wt.% of the total composition of the components, degree of ethoxylation 7-12, alkyl residue contains 8-12 carbon atoms) were added. The mixture was stirred for 80 minutes, after which it was cooled to a temperature of 18 °C and 77 g of triethylene glycol (15 wt.% of the total composition of the components) were added. The mixture was stirred for 60 minutes.

The acid number of the product was 169 mg KOH/1 g of product, the hydrogen ion activity index of 1% aqueous solution was 1.3. The product was a viscous transparent liquid of dark yellow color.

Example 3

350 g of a 5:1 molar mixture of ethoxylated synthetic higher fatty alcohols C ₁₀ -C ₁₅ with a degree of ethoxylation of 6-10 (68 wt.% of the total composition of the components) and polyphosphoric acid (14 wt.% of the total composition of the components) were loaded into a reactor. The reaction mixture was heated to 100 °C with stirring (stirring intensity 200-250 rpm) for 3 h. The product was cooled to 50 °C and 39 g of ethoxylated alkylphenol (9 wt.% of the total composition of the components, degree of ethoxylation 7-12, alkyl residue contains 8-12 carbon atoms) were added. The mixture was stirred for 50 minutes, after which it was cooled to a temperature of 22 °C and 43 g of triethylene glycol (10 wt.% of the total composition of the components) were added. The mixture was stirred for 40 minutes.

The acid number of the product was 138 mg KOH/1 g of product, the hydrogen ion activity index of 1% aqueous solution was 2.4. The product was a viscous transparent liquid of dark yellow color.

Example 4

350 g of a 4:1 molar mixture of ethoxylated synthetic higher fatty alcohols C ₁₀ -C ₁₅ with a degree of ethoxylation of 6-10 (60 wt.% of the total composition of the components) and polyphosphoric acid (15 wt.% of the total composition of the components) were loaded into a reactor. The reaction mixture was heated to 70 °C with stirring (stirring intensity 200-250 rpm) for 2 h. The product was cooled to 50 °C and 48 g of ethoxylated alkylphenol (10 wt.% of the total composition of the components, degree of ethoxylation 7-12, alkyl residue contains 8-12 carbon atoms) were added. The mixture was stirred for 60 minutes, after which it was cooled to a temperature of 25 °C and 65 g of triethylene glycol (14 wt.% of the total composition of the components) were added. The mixture was stirred for 30 minutes.

The acid number was 151 mg KOH/1 g of product, the hydrogen ion activity index of 1% aqueous solution was 1.8. The product was a viscous transparent liquid of dark yellow color.

Complex surfactants according to examples and their performance characteristics are presented in Table 2.

Table 2

No. Name of the indicator Prototype Sample 1 Sample 2 Sample 3 Sample 4 1 Appearance at temperature (20±2)°С Transparent liquid without mechanical inclusions of dark yellow color 2 Acid value, mg KOH per 1 g of product 132 148 169 138 151 3 Wettability of hydrophobic aluminum powder containing 3 wt.% surfactant Does not get wet It gets wet It gets wet It gets wet It gets wet 4 Volume of gas released in 2 minutes during the reaction of aluminum powder containing 3 wt.% surfactant with a solution of Ca(OH) ₂ , ml 3 12 9 16 10 5 Slowing down the kinetics of gas evolution of aged powders containing 3 wt.% surfactants, 8 min, % 24.7 3.6 5.5 5.1 4.2 6 Change in viscosity of aerated concrete mixture containing 0.15 wt.% surfactant, % 0.4 3.3 3.8 2.8 3.5

Thus, the obtained surfactant for the production of aluminum pastes, in comparison with the prototype, has all the necessary properties that improve the product:

- good wetting ability with respect to hydrophobic aluminum powders;

- the presence of an optimal level of inhibitory effect of surfactants on aluminum particles, which prevents chemical interaction between aluminum and solvent when it is added to hydrophilic aluminum powder;

- slows down the onset of the gas evolution reaction of aluminum pastes in lime mortar;

- leads to a change in the rheological properties of aerated concrete mixtures produced on the basis of aluminum pastes using this surfactant;

- ensures the preservation of the quality characteristics of aluminum pastes during storage for the entire required period (12 months).

Claims (10)

1. A surfactant for the production of aluminum pastes, which is a product of the interaction of polyphosphoric acid with ethoxylated synthetic higher fatty alcohols, oxyethylated alkylphenols and triethylene glycol, in the following ratio of components, wt. %: ethoxylated synthetic higher fatty alcohols 60-67 polyphosphoric acid 14-17 oxyethylated alkylphenols 9-16 triethylene glycol 10-15, in this case, the molar ratio of the components ethoxylated synthetic higher fatty alcohols: polyphosphoric acid is 3-5: 1. 2. The substance according to paragraph 1, characterized in that alcohols of the following formula are used as ethoxylated synthetic fatty alcohols: C _n H _2n+1 (C ₂ H ₄ O) _m CH ₂ CH ₂ OH (n=10-15; m=6-10). 3. The substance according to paragraph 1, characterized in that the oxyethylated alkylphenols used are substances of the following chemical formula: where n = 7-12, R = C ₈ - C ₁₂ . 4. A method for producing a surfactant for the production of aluminum pastes, which includes using polyphosphoric acid as a phosphorylating agent, characterized in that it includes mixing the components according to paragraph 1, wherein at the first stage ethoxylated synthetic higher fatty alcohols are mixed with polyphosphoric acids while maintaining a temperature of 70-100°C for 2-4 hours with stirring at 200-250 rpm, followed by cooling the mixture to 40-50°C for 45-90 min, at the second stage oxyethylated alkylphenols are added while stirring at 200-250 rpm of the mixture for 50-80 min, followed by cooling the mixture to 18-25°C for 45-60 min, and at the last stage triethylene glycol is added to the mixture while stirring at 150-200 rpm for 30-60 min. 5. The method according to claim 4, characterized in that at the first stage a mixture of mono- and diesters of phosphoric acid and ethoxylated synthetic higher fatty alcohols, an excess of ethoxylated synthetic higher fatty alcohols that have not entered into reaction, and orthophosphoric acid H ₃ PO ₄ are obtained. 6. The method according to item 5, characterized in that the content of orthophosphoric acid H ₃ PO ₄ in the mixture does not exceed 5 wt.%.