WO2022172054A1

WO2022172054A1 - A new hyperbranched-polycarboxylate superplasticizer and its preparation

Info

Publication number: WO2022172054A1
Application number: PCT/IB2021/051049
Authority: WO
Inventors: Mohammadreza SHARBAF; Farid HAJAREH HAGHIGHI; Davood Mostofinejad
Original assignee: Sharbaf Mohammadreza
Priority date: 2021-02-10
Filing date: 2021-02-10
Publication date: 2022-08-18

Abstract

A simplified-synthesis method based on low-temperature copolymerization of monomers without interference of oxygen is provided to produce a new cross-linked superplasticizer. This copolymer comprises three main components derived from: (I) an unsaturated-monocarboxylic acid with general formula [1], wherein R1 is H or CH3; (II) a crosslinking unsaturated-macromonomer represented by formula [2], wherein R2 and R3 are H or CH3, X is epoxy ethane and n is an integer number in the range of 10 to 200; (III) an unsaturated-polyethylene glycol macromonomer having an alkenyl group consisting 4 or 5 carbon atoms and oxyalkylene moiety comprising 2 to 30 carbon atoms in which the average number of oxyalkylene groups is within the range of 10-300. The general structure of this final component is represented by formula [3], wherein m is 1 (or 2) number and z is an integer number in the range of 5 to 150.

Description

A new hyperbranched-polycarboxylate superplasticizer and its preparation method

Detailed description of the embodiments:

The superplasticizer described in the present invention is a copolymer possessing three main constitutional units including: an unsaturated monocarboxylic acid such as acrylic acid and/or methacrylic acid (monomer A); a hyperbranched-macromonomer (monomer B); and an unsaturated poly( ethylene glycol) ether such as isoprenyl oxy poly( ethylene glycol) ether and/or α-methallyl-ω-hydroxy poly(ethylene glycol) ether (monomer C).

The molar ratio of A/B/C monomers is fitly in the range of (0.01 to 0.1)/(0 to 0.01)/(0 to 0.02). If the molar amount of A is lower than (B + C), the dispersing character of the resultant polymer decreases significantly.

In the production process of final product, according to the present invention, a chain-transfer agent is employed and the reaction carried out at pH less than 5 during the copolymerization.

The chain-transfer agent can be selected from the following compounds: (I) thiol-containing compounds such as thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thioglycerol, mercaptoethanol, and 3-mercaptopropionate; (II) secondary alcohols such as isopropanol; (III) halogenated compounds such as bromotrichloroethane, bromoform, carbon tetrachloride, bromotrichloroethane, and methylene dichloride. During the reaction, the chain-transfer agent must exist in the solution; hence, it is added continuously over the time domain of reaction, for example, through dropwise addition. To control the molecular weight of the final product, the concentration of chain-transfer must be kept at the same level during the polymerization. The large concentration variance between the beginning and the end of the reaction, results in a broad size distribution in the molecular weight of the target product. It is preferable that the chain-transfer is injected into the reactor through a different inlet from that employed for supplying the unsaturated monocarboxylic acid (monomer A). For example, if the chain-transfer agent is placed in the same dropping funnel containing the monomer A, the chain-transfer initiates a partial homopolymerization of the unsaturated acid which this reaction is considered as a negative side -reaction.

In this reaction, the conventional polymerization initiators can be applied such as: (I) peroxides such as hydrogen peroxide and persulfate salts (for example, potassium persulfate, sodium persulfate, and ammonium persulfate); (II) azo-nitriles (for example, 2-carbamoyl azo- isobutyronitrile), cyclic azo-amidine compounds (for example, 2,2'-azo-bis-2-(2-imidazolin-2-yl) propane hydrochloride), and azo-amidine compounds such as 2,2'-azo-bis-2- methylpropionamidine hydrochloride .

To start the reaction, it is preferable to use a redox polymerization initiator system such as a peroxide/reducing agent. The reducing agent can be selected from the following compounds: (I) organic compounds such as isoascorbic acid (salt), isoascorbic acid ester, L-ascorbic acid (salt), and L-ascorbic acid ester; (II) alkali metal sulfites such as sodium hydrogensulfite and sodium sulfite; (III) low valent metals such as Cu(II), Cr(II), Sn(II), V(II), Ti(III), and Fe(II); (IV) organic compounds comprising -SH group such as formaldehyde sodium sulfoxylate, and sodium dithionate; (V) amine compounds such as hydroxylamine, diethanolamine, triethanolamine, monoethanolamine, and hydrazine; (VI) sugars such as D-glucose and

D-fructose. Although, there can be a various combinations for redox initiator systems, but a combination of peroxide and reducing agent is more preferable, such as hydrogen peroxide/L- ascorbic acid, hydrogen peroxide/isoascorbic acid, and hydrogen peroxide/Mohr's salt. The most effective combination is hydrogen peroxide/L- ascorbic acid. The molar ratio of the peroxide to total monomers is preferably in the range of 0.01 to 0.1. The ratio less than 0.01, results in enhancing the unreacted monomers and the ratio more than 0.1, leads to a plenty of oligomer portion.

The molar ratio of the reducing agent is preferably in the range of 0.01 to 0.1 of the peroxide. The ratio less than 0.01, does not generate enough active radicals which increase the unreacted monomers. Conversely, the high ratio (more than 0.1), enhances the unreacted residual reducing agent. It is worth mentioning that the redox initiating system must always exist in the reactor during the copolymerization. To provide this condition, the dropwise addition of this initiating system is preferable. If the redox system is added quickly, it would be difficult to control the reaction because the radical concentration suddenly decreases resulting in a large variation in the radical concentration to the monomers in the beginning of the reaction compared to the latter half of the reaction which generates plenty of unreacted monomers thereafter. So, the size distribution of the final product becomes broad and consequently the capacity of the cement admixture becomes low.

To obtain high monomer reactivity, the temperature must be consistent with the half-life of the initiator which is preferable to be in the range of 3 to 10 hours. For instance, if hydrogen peroxide is applied with L-ascorbic acid as the redox system, the temperature and time of the reaction are fitly in the range of 40 to 70°C and 4 to 6 hours, respectively. The temperature and time out of these range result in low productivity. The present invention is further described through the following embodiments. For simplicity, the macromonomers are encoded (see Table 1) and in the embodiments, these codes are used (instead the complete name of the monomers). It is worth mentioning that the invention is not necessarily restricted to these examples. The effectiveness of the synthesized polymers was evaluated on the mortar with the components presented in Table 2.

Table 1: Code of monomers

Embodiment 1

A four-necked flask supplemented with a stirrer, a reflux condenser and two dropping funnels, was charged with 30.67 parts of tap water and 41.25 parts of B monomer, and then this mixture was heated to 55°C until the entire solid dissolved. Then, 0.20 parts of aqueous hydrogen peroxide (30% w/w solution) were added, followed by simultaneous dropwise addition of solutions I and II. Solution I comprises 8.83 parts of A1 monomer, and solution II composes 0.11 parts of thioglycolic acid, and 0.072 parts of aqueous L-ascorbic acid. The solutions I and II were inserted into the reaction mixture over periods of 3 and 3.5 hours, respectively. The temperature was constantly checked to be kept at 55°C for 4.5 hours (to complete the reaction). To neutralize the resultant mixture, sodium hydroxide solution (20.0% w/w) was added to adjust pH 7.

Embodiment 2

A four-necked flask supplemented with a stirrer, a reflux condenser and two dropping funnels, was charged with 30.67 parts of tap water and a combination of C1 and B macromonomers (C1 = 16.50 parts, B = 20.62 parts), and then this mixture was heated to 55°C until the entire solid dissolved. Then, 0.20 parts of aqueous hydrogen peroxide (30% w/w solution) were added, followed by simultaneous dropwise addition of solutions I and II. Solution I comprises 8.83 parts of A1 monomer, and solution II composes 0.11 parts of thioglycolic acid, and 0.072 parts of aqueous L-ascorbic acid. The solutions I and II were inserted into the reaction mixture over periods of 3 and 3.5 hours, respectively. The temperature was constantly checked to be kept at 55°C for 4.0 hours (to complete the reaction). To neutralize the resultant mixture, sodium hydroxide solution (20.0% w/w) was added to adjust pH 7.

Embodiment 3

A four-necked flask supplemented with a stirrer, a reflux condenser and two dropping funnels, was charged with 30.67 parts of tap water and a combination of C1 and B macromonomers (C1 = 23.10 parts, B = 12.37 parts), and then this mixture was heated to 55°C until the entire solid dissolved. Then, 0.20 parts of aqueous hydrogen peroxide (30% w/w solution) were added, followed by simultaneous dropwise addition of solutions I and II. Solution I comprises 8.83 parts of A1 monomer, and solution II composes 0.11 parts of thioglycolic acid, and 0.072 parts of aqueous L-ascorbic acid. The solutions I and II were inserted into the reaction mixture over periods of 3 and 3.5 hours, respectively. The temperature was constantly checked to be kept at 55°C for 4.5 hours (to complete the reaction). To neutralize the resultant mixture, sodium hydroxide solution (20.0% w/w) was added to adjust pH 7.

Embodiment 4

A four-necked flask supplemented with a stirrer, a reflux condenser and two dropping funnels, was charged with 30.67 parts of tap water and a combination of C1, C2 and B macromonomers (C1 = 11.00 parts, C2 = 11.00 parts, B = 14.40 parts), and then this mixture was heated to 55 °C until the entire solid dissolved. Then, 0.20 parts of aqueous hydrogen peroxide (30% w/w solution) were added, followed by simultaneous dropwise addition of solutions I and II. Solution I comprises 8.83 parts of A1 monomer, and solution II composes 0.11 parts of thioglycolic acid, and 0.072 parts of aqueous L-ascorbic acid. The solutions I and II were inserted into the reaction mixture over periods of 3 and 3.5 hours, respectively. The temperature was constantly checked to be kept at 55°C for 4.5 hours (to complete the reaction). To neutralize the resultant mixture, sodium hydroxide solution (20.0% w/w) was added to adjust pH 7.

Embodiment 5

A four-necked flask supplemented with a stirrer, a reflux condenser and two dropping funnels, was charged with 30.67 parts of tap water and a combination of C1 and B macromonomers (C1 = 13.20 parts, B = 24.75 parts), and then this mixture was heated to 55°C until the entire solid dissolved. Then, 0.23 parts of aqueous hydrogen peroxide (30% w/w solution) were added, followed by simultaneous dropwise addition of solutions I and II. Solution I comprises 8.83 parts of A1 monomer, and solution II composes 0.11 parts of thioglycolic acid, and 0.070 parts of aqueous L-ascorbic acid. The solutions I and II were inserted into the reaction mixture over periods of 3 and 3.5 hours, respectively. The temperature was constantly checked to be kept at 55°C for 4.5 hours (to complete the reaction). To neutralize the resultant mixture, sodium hydroxide solution (20.0% w/w) was added to adjust pH 7.

Embodiment 6

A four-necked flask supplemented with a stirrer, a reflux condenser and two dropping funnels, was charged with 26.67 parts of tap water and a combination of C1 and B macromonomers (C1 = 9.90 parts, B = 28.87 parts), and then this mixture was heated to 55°C until the entire solid dissolved. Then, 0.20 parts of aqueous hydrogen peroxide (30% w/w solution) were added, followed by simultaneous dropwise addition of solutions I and II. Solution I comprises 8.83 parts of A1 monomer, and solution II composes 0.13 parts of thioglycolic acid, and 0.052 parts of aqueous L-ascorbic acid. The solutions I and II were inserted into the reaction mixture over periods of 3 and 3.5 hours, respectively. The temperature was constantly checked to be kept at 55°C for 4.5 hours (to complete the reaction). To neutralize the resultant mixture, sodium hydroxide solution (20.0% w/w) was added to adjust pH 7.

Embodiment 7

A four-necked flask supplemented with a stirrer, a reflux condenser and two dropping funnels, was charged with 30.67 parts of tap water and a combination of C1 and B macromonomers (C1 = 16.50 parts, B = 20.62 parts), and then this mixture was heated to 55°C until the entire solid dissolved. Then, 0.25 parts of aqueous hydrogen peroxide (30% w/w solution) were added, followed by simultaneous dropwise addition of solutions I and II. Solution I comprises 6.45 parts of A2 monomer, and solution II composes 0.11 parts of thioglycolic acid, and 0.072 parts of aqueous L-ascorbic acid. The solutions I and II were inserted into the reaction mixture over periods of 3 and 3.5 hours, respectively. The temperature was constantly checked to be kept at 55°C for 4.5 hours (to complete the reaction). To neutralize the resultant mixture, sodium hydroxide solution (20.0% w/w) was added to adjust pH 7.

Embodiment 8

A four-necked flask supplemented with a stirrer, a reflux condenser and two dropping funnels, was charged with 30.67 parts of tap water and a combination of C1 and B macromonomers (C1 = 16.50 parts, B = 20.62 parts), and then this mixture was heated to 55°C until the entire solid dissolved. Then, 0.20 parts of aqueous hydrogen peroxide (30% w/w solution) were added, followed by simultaneous dropwise addition of solutions I and II. Solution I comprises 6.45 parts of A2 monomer, and solution II composes 0.11 parts of thioglycolic acid, and 0.072 parts of aqueous L-ascorbic acid. The solutions I and II were inserted into the reaction mixture over periods of 3 and 3.5 hours, respectively. The temperature was constantly checked to be kept at 55°C for 4.5 hours (to complete the reaction). To neutralize the resultant mixture, sodium hydroxide solution (20.0% w/w) was added to adjust pH 7.

Embodiment 9

A four-necked flask supplemented with a stirrer, a reflux condenser and two dropping funnels, was charged with 30.67 parts of tap water and a combination of C1 and B macromonomers (C1 = 16.50 parts, B = 20.62 parts), and then this mixture was heated to 55°C until the entire solid dissolved. Then, 0.20 parts of aqueous hydrogen peroxide (30% w/w solution) were added, followed by simultaneous dropwise addition of solutions I and II. Solution I comprises 8.83 parts of A2 monomer, and solution II composes 0.10 parts of thioglycolic acid, and 0.072 parts of aqueous L-ascorbic acid. The solutions I and II were inserted into the reaction mixture over periods of 3 and 3.5 hours, respectively. The temperature was constantly checked to be kept at 55°C for 4.5 hours (to complete the reaction). To neutralize the resultant mixture, sodium hydroxide solution (20.0% w/w) was added to adjust pH 7.

Embodiment 10

A four-necked flask supplemented with a stirrer, a reflux condenser and two dropping funnels, was charged with 30.67 parts of tap water and 33.03 parts of B monomer, and then this mixture was heated to 55°C until the entire solid dissolved. Then, 0.20 parts of aqueous hydrogen peroxide (30% w/w solution) were added, followed by simultaneous dropwise addition of solutions I and II. Solution I comprises 8.83 parts of aqueous acrylic acid, and solution II composes 0.11 parts of thioglycolic acid, and 0.072 parts of aqueous L-ascorbic acid. The solutions I and II were inserted into the reaction mixture over periods of 3 and 3.5 hours, respectively. The temperature was constantly checked to be kept at 55°C for 4.5 hours (to complete the reaction). To neutralize the resultant mixture, sodium hydroxide solution (20.0% w/w) was added to adjust pH 7.

The dispersing effectiveness of the synthesized embodiments was exanimated by a minislump test utilizing a conical mold with base diameter of 100 mm, top diameter of 70 mm and height of 50 mm. Cement pastes with water to cement ratio of 0.32 and superplasticizer dosage of 0.2% by weight of cement were prepared based on ASTM C305-20. Normal Portland cement (type I) was utilized. Cement and 67% of the mixture water were mixed in a mortar mixer for 2 minutes. Then superplasticizer and the remaining water which were already mixed, were incorporated into the mixture. The mixing was continued for 3 minutes with maximum speed. The prepared paste was filled into the mentioned cone in two layers. After lifting the cone, the diameter of the paste as spread on a glass table was measured in two perpendicular directions and the average value (in cm) was recorded as the mini-slump flow value. As shown in Table 2, the product of embodiment 10 shows the best performance processing high initial and final slump in low W/C ratio (0.32). The formulation of this patent can be extended to the industry due to its simplified-synthesis method.

Table 2. Slump of the products

Claims

What is claimed is:

1. A method for preparing a new hyperbranched-copolymer which is a single-step radical copolymerization of the three main monomers (A, B and C) in aqueous solution in which the molar ratio of the monomers are: 4.87 < A/(B + C) < 6.09

2. A method for preparing a new hyperbranched-copolymer as claimed in claim 1 in which the general formula of monomer A is shown as [1]:

wherein R₁ is H or CH₃.

The general formula of monomer B is shown as [2] :

wherein R₂ and R₃ are H or CH₃, X is epoxy ethane and n is an integer number in the range of 10 to 200.

The general formula of monomer C is shown as [3]: wherein m is 1 (or 2) number and z is an integer number in the range of 5 to 150.

3. A method for preparing a new hyperbranched-copolymer as claimed in claims 1 and 2 in which the monomer A can be selected from acrylic acid and/or methacrylic acid.

4. A method for preparing a new hyperbranched-copolymer as claimed in claims 1-3 in which the monomer B is a hyperbranched-macromonomer with molecular weight of 1500-4000 g/mol.

5. A method for preparing a new hyperbranched-copolymer as claimed in claims 1-4 in which the monomer C can be selected from isoprenyl oxy poly(ethylene glycol) ether and/or α-methallyl-ω-hydroxy poly(ethylene glycol). The molecular weights of these macromonomers are within in the range of 1000-3000 g/mol.

6. A method for preparing a new hyperbranched-copolymer as claimed in claims 1-5 in the presence of dissolved-oxygen (O_2(aq)) without any degassing with inert compounds (such as N_2(g) and Ar_(g)).

7. A method for preparing a new hyperbranched-copolymer as claimed in claims 1-6 in which a chain-transfer agent is employed to control the molecular weight of the final product. The chain transfer agent can be selected from the following compounds: (I) thiol -containing substrates such as thioglycolic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, thioglycerol, mercaptoethanol, and 3-mercaptopropionate; (II) secondary alcohols such as isopropanol; (III) halogenated compounds such as bromotrichloroethane, bromoform, carbon tetrachloride, bromotrichloroethane, and methylene dichloride.

8. A method for preparing a new hyperbranched-copolymer as claimed in claims 1-7 which contains an initiator to start the polymerization reaction. This initiator can be selected from: (I) peroxides such as hydrogen peroxide and persulfate salts (for example, potassium persulfate, sodium persulfate, and ammonium persulfate); (II) azo nitriles (for example, 2-carbamoyl azoisobutyronitrile), cyclic azo amidine compounds (for example, 2,2'-azobis-2-(2- imidazolin-2-yl) propane hydrochloride), and azo amidine compounds such as 2,2'-azobis-2- methylpropionamidine hydrochloride .

9. A method for preparing a new hyperbranched-copolymer as claimed in claims 1-8 which comprises a reducing agent to form a redox initiating system. Reducing agent can be selected from the following compounds: (I) organic compounds such as isoascorbic acid (salt), isoascorbic acid ester, L-ascorbic acid (salt), and L-ascorbic acid ester; (II) alkali metal sulfites such as sodium hydrogensulfite and sodium sulfite; (III) low valent metals such as Cu(II), Cr(II), Sn(II), V(II), Ti(III), and Fe(II); (IV) organic compounds comprising -SH group such as formaldehyde sodium sulfoxylate and sodium dithionate; (V) amine compounds such as hydroxylamine, diethanolamine, triethanolamine, monoethanolamine, and hydrazine; (VI) sugars such as D-glucose and D-fructose.

10. A method for preparing a new hyperbranched-copolymer as claimed in claims 1-9 in which the time of the reaction is in the range of 3.5 to 7 hours. To provide the maximum monomer reactivity, the reaction is carried out at 40-70°C.