Sequestering agent used in detergents with high calcium binding capacity

Abstract

 The present invention relates to the synthesis of the maleic acid/acrylic acid/sodium vinyl sulfonate terpolymer not posing an environmental risk and comprising substituted sulfonate groups (SO₃). In particular, the present invention relates to the utilization of said synthesized polymer in the production of cleaning products as sequestering agent.

Description

Field of the Invention

[0001] The present invention relates to polycarboxylate syntheses that are not harmful to the environment and comprising substituted groups such as sulfonate. In particular, the present invention comprises terpolymers obtained from acrylic acid, maleic acid and sodium vinyl sulfonate and used in the production of cleaning products.

Prior Art

[0002] Detergents are chemicals having cleaning feature. Said products can be in the form of powder, liquid or cream. Many different chemicals are used in detergent manufacturing. Sequestering (chelating) agents are one of the most important chemicals used in the production of detergents. Following are used as the sequestering agents in powder detergents, liquid detergents and shampoos, respectively: Na₅P₃O₁₀ (sodium tripolyphosphate, STPP); K₅P₃O₁₀ (potassium tripolyphosphate, KTPP) and the carboxylates; and Na₄-EDTA. In recent years, polycarboxylates are improved and started to be used in the detergent and textile industry. Polycarboxylates have superior properties compared to the known sequestering agents.

[0003] In the studies conducted for the present invention, terpolymers are synthesized using acrylic acid, maleic acid and sodium vinyl sulfonate. When calcium binding capacity of these polymers is measured, better results as compared to the other sequestering agents available in the market are obtained.

[0004] Known developments of the current state of the art on the subject matter are given below.

[0005] Patent numbered US 3,635,915 describes polymerization of acrylic acid and maleic acid and investigation of utilization characteristics thereof as surface coating.

[0006] Patent numbered US 3,624,048 relates to the use of sulfonated polymaleic anhydride in detergents. Said invention describes various experiments being conducted in order to obtain sulfonated polymaleic anhydride in the presence of tetrachlorethylene by means of passing SO₃ gas.

[0007] Patent numbered US 3,903,039 relates to synthesis of terpolymers comprising sulfonate groups and utilization areas of said terpolymers. In said invention, isobutylene-cyclopentadiene copolymer is sulfonated in dioxane/SO₃ using pure hexane.

[0008] Patent numbered US 4,450,261 relates to low molecular weight styrene-maleic anhydride copolymers and sulfonated structures thereof. The styrene-maleic anhydride copolymers obtained by said invention are synthesized using a variety of mercaptan chain transfer agents and the resulting copolymers are investigated.

[0009] In patent numbered US 4,640,211 synthesis of acrylic acid-sodium vinyl sulfonate-vinyl acetate terpolymers and effectiveness of said terpolymers as dispersant in industrial water systems are mentioned.

[0010] Patent numbered US 4,709,091 relates to the production of polymaleic acid polymer. Synthesis of maleic acid copolymers with peroxide catalyst upon conducting neutralization thereof with alkali metal hydroxide or ammonia is investigated.

[0011] Patent numbered AU7778187 discloses styrene sulfonate/methyl styrene copolymer synthesis in styrene.

[0012] Patent numbered WO 91/17189 discloses calcium binding capacity of the polycarboxy compounds based on polysaccharide compounds and studies carried out on the usability thereof instead of phosphate in detergents.

[0013] Patent numbered US 5,135,677 relates to utilization of maleic acid polymers as water conditioners and detergent additives. In said invention, synthesis of polymaleic acid and maleic acid copolymers and role thereof in water conditioning are investigated. Patent numbered US 2002/0035224 A1 relates to manufacturing and utilization methods of copolymers of acrylic-maleic acid (or salts thereof). In said invention, polymerization of maleic anhydride in the presence of acrylic acid and hydrogen peroxide catalyst and comparison of factors such as different pH and molecular weight are investigated.

[0014] Patent numbered US 2004/0014623 A1 discloses effects of polycarboxylic acid sequestering agents on different pH values. In addition, experiments are carried out in different types of detergent formulations.

[0015] Patent numbered WO 2005/090540 relates to synthesis of sulfonate/carboxylate polymers and the use of said polymers in the detergent formulations. In said invention, acrylic acid, styrene, sodium methallyl sulfonate and sodium phenyl methallyl ether compounds are used together for synthesis of said polymers.

[0016] Patent numbered WO 2011/061655 A2 discloses the matrix of the conversion of the sulfonate/carboxylate polymers into the solid state with sodium carbonate.

[0017] In detergents, following are used as sequestering agents: Na₅P₃O₁₀ (STPP), Na₄-EDTA (sodium salt of ethylenediaminetetraacetic acid), citric acid, phosphonate (for example, DTPA: Diethylenetriaminepentaacetic acid) and polycarboxylates. Substances other than polycarboxylates pose a risk to the environment. Therefore, restrictions are brought on the use of sequestering agents.

[0018] The polycarboxylates available on the market are in the form of acrylic acid homopolymer (PA) and acrylic acid/maleic acid copolymer (PMA). In recent times, terpolymers containing sulfonate groups are also synthesized. Sulfonate groups are present in the terpolymer structures formed by using styrene sulfonic acid monomers. In another method, sulfonate groups obtained in solvent medium by passing SO₃ gas are added to the structures (Patent numbered US 3,624,048). However, the use of solvents in industrial applications poses risks.

[0019] The use of styrene sulfonic acid in synthesized terpolymers is environmentally risky. Benzene ring is present in the styrene sulfonic acid structure. Benzene is a biologically toxic compound. Therefore, the presence thereof in the biodegradation products is an undesired situation.

[0020] Due to all of said drawbacks, a need for innovation regarding the sequestering agents used in the manufacturing of cleaning products has arisen.

Brief Description of the Invention

[0021] The present invention is developed by being inspired from existing situations and seeks to solve the above mentioned drawbacks.

[0022] The primary object of the present invention is to synthesize a polymer that can be used instead of sequestering agents in the production of cleaning products.

[0023] The present invention aims to obtain a sequestering agent that is not environmentally hazardous.

[0024] An object of the present invention is to obtain polymer structures having calcium binding capacity higher than that of the existing sequestering agents.

[0025] The present invention also aims to synthesize terpolymers using acrylic acid, maleic acid and sodium vinyl sulfonate.

[0026] Another object of the present invention is to synthesize polymers, biodegradation products of which are not toxic.

[0027] Another object of the present invention is to reduce the damage of the cleaning products to the environment.

[0028] Another object of the present invention is to increase the number of alternative substances that can be used instead of sequestering agents in the production of detergents.

[0029] Another object of the present invention is to produce cleaning products that are more environmentally friendly.

[0030] The present invention, in order to fulfill the objects mentioned above, relates to a sequestering agent used in the production of cleaning products, wherein it comprises maleic acid/acrylic acid/sodium vinyl sulfonate terpolymer.

[0031] The present invention, in order to fulfill the objects mentioned above, relates to a sequestering agent obtaining method, wherein said terpolymer is obtained by the reaction of %5-30% by weight of maleic acid, %1-7% by weight of sodium vinyl sulfonate, and 30%-80% by weight of acrylic acid in the presence of 0.05%-5% by weight of a peroxide based catalyst and 0.01 %-2% by weight of an inhibitor.

[0032] The structural and the characteristic features and all the advantages of the present invention will be understood more clearly with the following detailed description. Therefore, the evaluation needs to be done by taking this detailed description into consideration.

Figures

[0033] 

Figure 1: Graphic of the results of GPC chromatogram of the synthesized Terpolymer 1.

Figure 2: Graphic of the results of GPC chromatogram of the synthesized Terpolymer 2.

Figure 3: Graphic of the results of GPC chromatogram of the synthesized Terpolymer 3.

Detailed Description of the Invention

[0034] In this detailed description, the sequestering agent according to the present invention and preferred embodiments thereof are described only for a better understanding of the subject without constituting any restrictive effect.

[0035] The present invention comprises terpolymers obtained from acrylic acid, maleic acid, sodium vinyl sulfonate and used in the production of cleaning products. In particular, said terpolymers can be used as sequestering agents in the production of detergents.

[0036] In the conducted studies regarding the present invention, calcium binding properties of the synthesized polymer structures and usability thereof in the liquid and powder detergent products in comparison with the known sequestering agents are investigated. In particular, spray mixing process is used for investigation of the suitability of said polymer structures for powder detergents. For this reason, a laboratory scale reactor is designed and powder detergent production and appropriate utilization conditions of the investigated sequestering agents are determined in said reactor. Production trials and characteristics of the produced detergents are investigated.

[0037] Acrylic acid (C₃H₄O₂)/maleic acid (C₄H₄O₄)/sodium vinyl sulfonate (C₂H₃NaO₃S) terpolymer is synthesized at a temperature of 90-95 °C by using an inhibitor and a peroxide based catalyst during the reaction time required for polymerization (1-3 hours). Ammonium peroxydisulfate ((NH₄)₂S₂O₈) is used as the peroxide based catalyst and sodium bisulfite (NaHSO₃) is used as the inhibitor.

[0038] Mass percentages of the acrylic acid, maleic acid, sodium vinyl sulfonate, inhibitor and the catalyst used in the synthesis of the terpolymer are given below in Table 1.

Table 1: Substances used in the synthesis of terpolymer structures and mass percentages thereof

Substance	Terpolymer 1	Terpolymer 2	Terpolymer 3
Acrylic acid	30%-80%	60%-80%	60%-80%
Maleic acid	5%-30%	15%-30%	15%-30%
Sodium vinyl sulfonate	1%-7%	3%-6%	4%-7%
Catalyst	0.05%-5%	0.1%-0.5%	0.1%-0.5%
Inhibitor	0.01%-2%	0.01%-0.05%	0.01%-0.05%

[0039] pH values of the Terpolymer 2 and Terpolymer 3 structures given above in Table 1 range between 1.5-2; pH value of the Terpolymer 1 ranges between 8.0-8.5. Solid materials present in the structures of said terpolymers (1, 2, 3) are in the range of 30%-40%.

[0040] Maleic acid/acrylic acid/sodium vinyl sulfonate terpolymers are polycarboxylates not posing an environmental risk and comprising substituted sulfonate groups (SO₃). The main role of the polycarboxylates in the cleaning products is that they inhibit Ca²⁺, Mg²⁺, Fe³⁺, Cu²⁺ and Zn²⁺ ions. Inhibition is taking place by keeping and dispersing these ions in the cage. Calcium binding capacity of the polycarboxylates is higher than the other sequestering agents.

[0041] Calcium binding properties of the existing sequestering agents and the polymer structures according to the present invention are given below in Table 2.

Table 2: Comparative Calcium Binding Capacities of the Sequestering Agents

Substance	Ca Binding - mg CaO/1 g of product
	20 °C	90 °C
Na-diphosphate	114	28
Na-tripolyphosphate	158	113
1-hydroxyethane-1,1-diphosphonic acid	394	378
Amino-tri(methylenephosphonic acid)	224	224
Nitrilotriacetic acid	285	202
N-(2-hydroxyethyl)-iminodiacetic acid	145	91
Ethylenediaminetetraacetic acid	219	154
1,2,3,4-cyclopentane-tetracarbonic acid	280	235
Citric acid	195	30
Polyacrylic acid	307	259
Poly(acrylic acid/maleic acid)	395	331
Poly(acrylic acid/maleic acid/sodium vinyl sulfonate) (Terpolymer 1)	350	310
Poly(acrylic acid/maleic acid/sodium vinyl sulfonate) (Terpolymer 2)	360	300
Poly(acrylic acid/maleic acid/sodium vinyl sulfonate) (Terpolymer 3)	208	148

[0042] As can be seen above in Table 2, terpolymers according to the present invention can be used instead of the existing sequestering agents. In addition, when the calcium binding capacities of said terpolymers are compared with the existing sequestering agents, better results are obtained.

[0043] In addition, the draft regulation numbered COM (2010) 597 for amending the Regulation (EC) No. 648/2004 being in force in the European Union (EU) as regards to the restriction on use of phosphates and other phosphorous compounds in household laundry detergents is published on 04.11.2010 by the European Commission. In the press release issued by the European Commission on 14.12.2011, following have been reported in accordance with the decision adopted by the Commission:

• As of June 30, 2013, in laundry detergents, use of phosphates will be banned and use of the other phosphorous compounds will be restricted,
• As of January 1, 2017, same will also be implemented for the products used in automatic dishwashers.

[0044] This situation increases the importance of polycarboxylate substances that do not constitute an environmental risk and provide better results in terms of performance.

[0045] Calcium binding capacities of said polymer structures are calculated by complexometric titration. Using said titration method, iron and magnesium ion binding capacities of the terpolymer according to the present invention are measured. The measured values are given below in Table 3.

Table 3: Ca, Mg and Fe ion Binding Capacity of the Maleic Acid/Acrylic Acid/Sodium Vinyl Sulfonate Terpolymer

Maleic Acid, Acrylic Acid, Sodium Vinyl Sulfonate Terpolymer (Terpolymer 2)	Ca (mg/g, 20°C)	Mg (mg/g, 20°C)	Fe (mg/g, 20°C)
	257	152	116

[0046] Molecular weight and distribution of a polymer are very important in terms of material properties. Typically, as the molecular weight of the structure increases, the complexity and intermolecular attractive forces of the structure increase. This means a shift in many properties of the polymer. For the polymers, average molecular weight is used instead of molecular weight due to the fact that the polymers are composed of polymer chains of different lengths.

[0047] The molecular weights of the synthesized terpolymers according to the present invention are measured by Shimadzu brand GPC. The average molecular weights thereof range from 14000 to 16000 g/mol. The measured values are given below in Table 4.

Table 4: Average molecular weights of the synthesized terpolymers

Substance	Terpolymer 1	Terpolymer 2	Terpolymer 3
Average Molecular Weight (g/mol)	15 473	14 613	14 822

[0048] In addition, graphs of the measurement results are also provided in Figures 1, 2 and 3. In Figures 1, 2 and 3, molecular weight measurements by GPC of the Terpolymer 1, Terpolymer 2, and Terpolymer 3 are shown against Mn, Mw, Mz and Mz1. Description of the terms mentioned in connection with these figures are given below.
Mn: Number average molecular weight
Mw: Weight average molecular weight
Mz: Z-average molecular weight
Mz1: Z+1 average molecular weight
G. lcd: Terpolymer 1
Bsey. lcd: Terpolymer 2
I. lcd: Terpolymer 3
Average: Average value
%RSD: Relative standard deviation
Maximum: The maximum point
Minimum: The minimum point
SD: Standard deviation

[0049] Experiments are carried out by using the polymers according to the present invention instead of STPP in powder dishwasher detergents. Firstly, solid forms of the synthesized polymers are obtained by drying at 105°C. The obtained solid terpolymer is labeled as POLYMER A (Terpolymer 2) and tested in 5 different formulas. The 5 different created detergent formulations and calcium binding capacities thereof are given below in Table 5.

Table 5: STPP and POLYMER A Comparison of Powder Dishwasher Detergent Formulas

Raw Materials	F-1	F-2	F-3	F-4	F-5
Sodium Carbonate, Na2CO3	60.00	60.00	60.00	60.00	60.00
TAED	0.15	0.15	0.15	0.15	0.15
Sodium Sulfate, Na2SO4	9.50	9.50	9.50	9.50	9.50
Nonionic Active Substance	2.00	2.00	2.00	2.00	2.00
STPP, Na5P3O10	18.00	10.00	8.00	4.00	-
POLYMER A	-	8.00	10.00	14.00	18.00
Enzyme	0.20	0.20	0.20	0.20	0.20
Sodium Disilicate, Na2O.2SiO2	5.00	5.00	5.00	5.00	5.00
Sodium Percarbonate, 2Na2CO3.3H2O2	5.00	5.00	5.00	5.00	5.00
Scent	0.15	0.15	0.15	0.15	0.15
Ca Binding Capacity (mg CaO/1 g of the product)	25.20	32.56	34.40	38.08	41.76

[0050] In the above table, weights of the raw materials used in production of the powder dishwashing detergent are given. As can be seen in Table 4, Polymer A of different weights is used instead of STPP. The terpolymer according to the present invention has a maleic acid/acrylic acid/sodium vinyl sulfonate structure. In addition, it is a compound being soluble in water and having a high calcium binding capacity. Thus, detergents having a better calcium binding capacity are obtained.

[0051] In the present invention, maleic acid/acrylic acid/sodium vinyl sulfonate terpolymer not posing a risk in terms of international use and environment and comprising substituted sulfonate groups (SO₃) is synthesized. Biodegradation products of the synthesized terpolymer are not toxic. Calcium binding capacities of said water soluble polymer structures are high.

Claims

1. Sequestering agent used in the production of cleaning products, characterized in that it comprises maleic acid/acrylic acid/sodium vinyl sulfonate terpolymer.

2. Method for obtaining the sequestering agent according to Claim 1, characterized in that said terpolymer is obtained by the reaction of %5-30% by weight of maleic acid, %1-7% by weight of sodium vinyl sulfonate, and 30%-80% by weight of acrylic acid in the presence of 0.05%-5% by weight of a peroxide based catalyst and 0.01 %-2% by weight of an inhibitor.

3. Method according to Claim 2, characterized in that said reaction is carried out at a temperature of 90-95°C.

4. Method according to Claim 2, characterized in that said catalyst is ammonium peroxydisulfate.

5. Method according to Claim 2, characterized in that said inhibitor is sodium bisulfite.

6. Method according to Claim 2, characterized in that realization duration of said reaction time is between 1 and 3 hours.

7. Utilization of the terpolymer according to Claim 1 in the production of cleaning products as sequestering agent.

Drawing