The use of methyl-cyclodextrin way reversible reduce the viscosity of the aqueous solution and gelled water system

 

(57) Abstract:

Methyl--cyclodextrin having a hydrophobic group can be used to reversibly reduce the viscosity of aqueous systems containing hydrophobic modified thickener without the addition of additional surfactants. 3 S. and 6 C.p. f-crystals, 3 tables.

The invention relates to thickeners for aqueous systems and eliminates the need to use organic co-solvent. More specifically, the invention relates to the use of methyl--cyclodextrin to reversibly reduce the viscosity of aqueous systems containing hydrophobic modified thickener, the way reversible reduce the viscosity of the aqueous solution and gelled water system.

Systems such as, for example, coatings containing emulsion polymer binder, usually include thickeners to obtain the desired degree of viscosity, necessary for the preparation and use of the water system. One of the main types of thickeners used in aqueous systems, experts termed "associative". Associative thickeners called because it is believed that the mechanism of thickening involves the formation of hydrophobic linkages between No, that many different types of associative thickeners include, but are not limited to, hydrophobic modified polyurethanes, hydrophobically modified emulsion, soluble in alkalis, hydrophobic modified acetylcellulose or other hydrophobic modified natural products and hydrophobically modified polyacrylamides.

Some of these associative thickeners, such as hydrophobic modified polyurethane thickeners, sold in the form of aqueous solutions containing organic cosolvent. The function of the organic co-solvent, such as propylene glycol and BUTYLCARBAMATE, is to reduce the viscosity of an aqueous solution containing an associative thickener allows to simplify the adjustment of its viscosity is used as a thickener. In performing its functions, the co-solvents have an adverse impact on the environment, safety and health. Suppression of viscosity can be achieved by the use of surfactants. They reduce coloring action, not presenting a special risk to health and environment.

More closely similar to the proposed invention is a JV is the conduct of complex formation of hydrophobic parts of the thickener with a predefined number of cyclodextrin with subsequent dokomplektovanie cyclodextrin and thickener, that allows the agent to perform its function (US 5137571, 92). The patent also States that ,-cyclodextrin and cyclodextrin can be effectively used to reduce the viscosity of aqueous solutions of hydrophobically modified thickeners. He also reveals that oxyethyl - and oxypropylated more preferable than non-modified cyclodextrin. The claimed product methyl--cyclodextrin is described in "Material Sefety Data Sheet", publ. Macker Chemic Gmbh, 18.08.92.

The objective of the invention is a further improvement of the process of suppressing the viscosity of an aqueous solution containing a hydrophobic modified thickener.

This object is achieved by the use of methyl--cyclodextrin having a hydrophobic group, for a reversible decrease in viscosity of the aqueous system containing hydrophobic modified thickener.

Thus preferably the water system is a paint.

The problem is solved also described by way of reversible reduction in the viscosity of an aqueous solution containing a hydrophobic modified thickener through complexation hydrophobic parts of the thickener with the predefined malodextrin to the water system, requiring thickening and subsequent zakompleksovany or desorption-cyclodextrin from the thickener under stirring, whereby according to the invention as a-cyclodextrin using methyl--cyclodextrin.

Thus preferably gidropony thickener is chosen from the group comprising hydrophobic modified polyethoxysiloxane urethanes, hydrophobically modified emulsion, soluble in alkalis, hydrophobic modified acetylcellulose and hydrophobically modified polyacrylamides.

Preferably also methyl--cyclodextrin decomplexed or desorbed from the thickener, adding a predetermined amount of anionic, nonionic or cationic surfactants, and surfactant added to the aqueous system at a concentration of one mole per mole of methyl--cyclodextrin.

Preferably the aqueous system is a paint.

This object is achieved also thickened water system, which according to the invention contains a hydrophobic modified thickener and methyl--cyclodextrin having a hydrophobic group.

Preferably thickened water sigo hydrophobic modified thickener, involves the following stages:

the complexation of hydrophobic parts of the thickener with a predefined number-cyclodextrin having a hydrophobic group;

- additive complex thickener and-cyclodextrin in the aqueous system to be thickened;

- dokomplektovanie or desorption-cyclodextrin with thickener.

Suddenly discovered that methyl--cyclodextrin, a modified version of the cyclodextrin, gives excellent lower viscosity compared with the preferred commercially available acetylcyclohexanone, and compared with the most preferred commercially available oxypropylation.

Cyclodextrins are oligosaccharides with a closed cycle with 6,7 or 8 molecules of D-glucose on the macrocycle. Cyclodextrins with 6 rings of glucose treat-cyclodextrins; cyclodextrins with 7 rings of glucose treat-cyclodextrins; cyclodextrins with 8 rings of glucose treat-cyclodextrins. Cyclodextrins are obtained from starch of any selected number of plants, such as corn, potato and waxy maize. The starch may be modified or unmodified, derived from cereals or clubrace to about 35 wt.% solids are generally thin by gilotinirovaniya or handling thinning enzyme such as bacterial enzyme, amylase, and then treated transglycosylation enzyme with the formation of cyclodextrins. The number of individual and cyclodextrins varies depending on the selected starch, enzyme transglycosylase and treatment conditions. The precipitation and isolation of the individual cyclodextrins are described in the literature, while using solvents, the compounds include, such as trichloroethylene, and nerastvorim system, including the selected ion-exchange resin. -cyclodextrin is the most widely used form and known for use in obtaining pharmaceuticals and food products.

Known ability of cyclodextrins to form inclusion complexes with organic compounds and to increase the water solubility of these organic compounds. In "Cyclodextrins Increase Surface Tension and Critical Micelle Concentrations of Detergent Solutions" W. Saenger and A. Muller-Fahrnow, Angew. Chem. Int. Ed. Egl. 27 (1988), No. 3, pages 393-394, the authors discuss the ability of the Central hydrophobic cavity of the compounds of cyclodextrins to accommodate hydrophobic aliphatic portion of the molecule detergent having a diameter of about 5 Studies with such detergents showed that cyclotec is icell detergent, to avoid foaming of the sample.

Patent UK 2189245 discloses A method of increasing the solubility of cyclodextrins in water. This method involves the modification of allencaron.com, preferably ethylene carbonate resulting from the formation of hydroxyethyl ethers on the ring structure.

Since connections cyclodextrins adsorbed on hydrophobic substances or form complexes with them, they can be absorbed by the hydrophobic parts of the associative thickeners. The absorbance of the compounds of cyclodextrin on the hydrophobic parts of the associative thickeners causes a decrease in the viscosity of an aqueous solution containing an associative thickener. Compounds of cyclodextrins can be easily decarbonate or zakompleksovani from associative thickener, adding another substance having an affinity for the cyclodextrin.

The solubility of methyl--cyclodextrin in water is about 80 g per 100 g of water. This limits the concentration of methyl--cyclodextrin which can be used to suppress the viscosity of an aqueous solution containing an associative thickener. While the viscosity of an aqueous solution containing an associative thickener increases with conc the real number, which can be added to the solution without the formation of undesirable solids. If the maximum concentration of methyl--cyclodextrin required to reduce the viscosity of an aqueous solution containing an associative thickener, to a reasonable value (for example, to a viscosity of about 2000 centipoise), exceeds the limit of solubility of methyl--cyclodextrin in water, methyl--cyclodextrin is not an effective additive for reducing the viscosity. In other words, the effectiveness of methyl--cyclodextrin as additives for reducing the viscosity is a function of the solubility of methyl--cyclodextrin and the solid content of the associative thickener in an aqueous solution. The higher the solids content of the associative thickener, the higher the viscosity containing aqueous solution, and the higher the concentration of cyclodextrin, which should be added to reduce the viscosity to a level where the solution flows easily. Found that the use of methyl--cyclodextrin effectively in the composition of latex paints to achieve different effects, such as:

- receipt and provision of low solution viscosity thickener with a high solids content without the use of solvent is thickeners, having limited solubility in water;

- weakening reduce the viscosity of mixtures containing an associative thickener, after the addition to the mixture of dyes or surfactants;

- increase efficiency directly associative thickener, as by reducing the amount of thickener required to ensure the viscosity of the ink;

- reduction of foaming in the paint in the presence or without the associative thickener, which is particularly desirable when the paint is applied with a roller; and

- solving the problems of improving the color associated with surface-active substances in some songs.

The ability methyl--cyclodextrin to decompensates from hydrophobic associative thickener is just as important as his ability in the first place be absorbed or complexometry with associative thickener. It is important that the thickener increases the viscosity of the water system, which add a solution of the associative thickener, which decomplexed from cyclodextrin or desorption of naturally cyclodextrin with hydrophobic parts of the molecules of the associative thickener. Found that methyl--cyclodextrin easily desorbed or de is tion to the cyclodextrin. It also found that for zakompleksovany or desorption cyclodextrin you can apply the usual surface-active agents are usually present in the water systems of coatings, including anionic surfactants, such as nutriceuticals, nonionic surfactants such as IGEPALCO-660 (10 M ethylate of Nonylphenol), and cationic surfactants. For this purpose it is possible to use other water-soluble organic solvents, such as ethanol and TEXANOLbut they are not preferred. For complete desorption or zakompleksovany preferable to apply about one mole decomplexer agent per mole of methyl--cyclodextrin was added to a solution of the associative thickener. And complexation, and zakompleksovany easily achieved by adding the reagents under stirring. At room temperature are not necessary stage special purification or separation. For zakompleksovany is not necessary to add additional amounts of surface-active substances, for example, found that quite a number of surfactant, which is present in the components of the attachment of other properties, different from rheological modifications. Typically, in the preparation of mixed paints the composition (in particular, surface-active substances) must be changed, maintaining the stability of the dispersion dyes, ensuring the absence of harmful effects on the dispersion of other components. In some compositions of the components of the paint, such as latex media, contribute to the composition incompatible surfactant. Correction to this song add additional surfactant to make the system compatible. Being effective in establishing system compatibility, these surfactants can tell compositions undesirable characteristics, such as sensitivity to water and foaming. Methyl--cyclodextrin is used to improve compatibility of the dye without the addition of additional surfactants.

The invention is illustrated by the following examples.

Example 1. Thickeners in water

Experienced methyl--cyclodextrin to demonstrate its ability to reduce the viscosity of the hydrophobic modified thickener in water is more effective than the preferred commeicial.

4.9 g of Each cyclodextrin is mixed with 77.6 g of water, and then add 17,5 g CRYSOLRM-8 solid hydrophobic modified polyurethane thickener and mix it with the solution. Reducing the viscosity of the mixture is determined using viscosimeter Brookfield.

The results (in centipoise) are given in table. 1.1 (see the end of the description).

Example 2. The thickening agent in the compositions of the inks

Were made of paint, in which the hydrophobic modified thickener complex with a cyclodextrin, for demonstration of the fact that methyl--cyclodextrin has no harmful effect on other properties of the ink compositions, in comparison with other cyclodextrins.

For the preparation of paints used the ingredients listed in table. 2.1 (see end of description) (in grams). In the container first, mix the ingredients for grinding at high speed, using a Cowles mixer, then add liquefy the ingredients and mix at low speed. In a separate container mix the cyclodextrin and the corresponding amount of water, then add the thickener and mix to homogeneity. After that, the complex mixture of thickening agent added is in the composition of the paint anionic surfactants. So there is no need to add to the composition an additional surface-active compound.

Example 3. Evaluation of the thickening agent in the compositions of the inks

Conducted several experiments illustrating the fact that the method according to the invention gives the best reduction in viscosity compared with other cyclodextrins, the method of the present invention has no adverse effect on other properties of the composition of the paint.

Efficiency

The efficiency of the thickener, complex with cyclodextrin, was measured by determining the amount of dry thickener (in pounds) required for thickening 100 gallons (378 l) of the paint composition to a value of approximately 95 Krebs Units (units KI - viscosity in Krebs units). Performance data are given in table. 3.1 (lbs/100 gallons and g/d) (see the end of the description).

ICI viscosity

The viscosity increase of the ink determined using ICI viscometer. The values of viscosity are given in table. 3.1 (pasah).

Over on Leneta

Determined the course and alignment of each color. Each dye is applied on a separate map Leneta 12H (sealed Leneta 12H chart) when 25oC and horizontal arrangement, dried over night. Wissende numbers of relevant standards, which is closest in appearance to each of the colors.

Influx on Leneta

Determined by the influx of each color. Each dye is applied in the form of a descending strip on a separate card Leneta 12H (sealed Leneta 12H chart with a line painted with water-soluble ink perpendicular to the length of the card, at 25oC and left to dry overnight in a vertical position. Dried the map estimate by the maximum thickness (measured in thousandths of inches), in which paint is deposited over a line drawn in water-soluble ink, less than 0.5 see the Results of determination of sedimentation are shown in table. 3.1.

Gloss (60oand 85o)

Determined the gloss of each color. Each paint put down on the map Leneta chart 5C c Bird film applicator (thickness 3 thousandths of a share of an inch = 76210-5cm) and dried at a constant temperature and humidity for 7 days. The gloss of each color is determined by the meter gloss hunter at 60oand 85oin accordance with ASTM-D-523-89.

The results of determination of the gloss given in table. 3.1.

Color stability

Determined the stability of each ink before and after the addition of 2 oz/gallon (~15 g/l) of dye, Lamp Black, PI> The heat resistance of

Determined the stability of each ink before and after curing by heating at 140oF (60oC) within 10 days, using a viscometer Krebs-stormer. The results of determining the viscosity and the Delta values are given in table. 3.1.

1. The use of methyl--cyclodextrin having a hydrophobic group, for a reversible decrease in viscosity of the aqueous system containing hydrophobic modified thickener.

2. Application under item 1, characterized in that the water system is a paint.

3. The way reversible decrease in viscosity of an aqueous solution containing a hydrophobic modified thickener through complexation hydrophobic parts of the thickener with a predefined number-cyclodextrin having a hydrophobic group, add a received complex thickener and-cyclodextrin to water system that require thickening and subsequent zakompleksovany or desorption-cyclodextrin from the thickener under stirring, wherein the as-cyclodextrin using methyl--cyclodextrin.

4. The method according to p. 3, characterized in that the hydrophobic thickener is chosen from the group klastorin alkalis, hydrophobic modified acetylcellulose and hydrophobically modified polyacrylamides.

5. The method according to p. 3 or 4, characterized in that methyl--cyclodextrin decomplexed or desorbed from the thickener, adding a predetermined amount of anionic, nonionic or cationic surfactants.

6. The method according to p. 5, characterized in that the surfactant added to the aqueous system at a concentration of 1 mol to 1 mol methyl--cyclodextrin.

7. The method according to PP.3, 4, 5 or 6, characterized in that the water system is a paint.

8. Thickened water system, characterized in that it contains a hydrophobic modified thickener and methyl--cyclodextrin having a hydrophobic group.

9. The system under item 8, characterized in that it is a paint.

 

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