Use of rhamnolipid and / or sophorolipid for increasing coverage and / or maintaining coating performance during storage of coating composition

Abstract

The present invention relates to the use of rhamnolipids and / or sophorolipids for increasing the coverage and / or maintaining the coating properties during the storage of a coating composition.

Description

[0001] The present invention relates to the use of rhamnolipids and / or sophorolipids for increasing coverage and / or for maintaining coating properties during storage of a coating composition.

[0002] Formulations for many coating tasks contain particles such as color pigments or fillers.

[0003] For the user of paint, the theoretical coverage of the coating composition is an important coating property. For an object with a coating, the theoretical coverage indicates how many m2 of surface area can be coated with one kilogram or liter of the coating composition. The calculation uses the layer thickness of the paint film with ideal hiding power that can be obtained under standard conditions. The theoretical coverage is a calculated limit value that is close to the value that can be achieved in practice. In the case of actual coverage, additional factors such as material losses must be taken into account, which factors vary according to the coating method (painting method), such as spraying or roller coating, and the substrate, such as rough, smooth or absorbent.

[0004] The coverage rate indicates the amount of paint required for an area to be coated in a hiding manner. The coverage rate is therefore an important piece of information not only in the context of technical aspects, such as the maximum quality of the substrate to be covered, but also from an economic point of view. The determined theoretical coverage rate enables the material required for the area to be coated to be comparable to the relevant coating costs for the user.

[0005] For the determination of coverage, please refer to the "Richtlinie zur Bestimmung des [Guide to Determining Hiding Power], July 2002 edition, Verband der deutschen Lackindustrie eV [Association of the German Coatings Industry]".

[0006] The hiding power of a paint is therefore one of the key quality criteria, based on the contrast of the paint applied to the test substrate in accordance with the guidelines and test specifications. Four levels of contrast are specified in DIN EN 13300:

[0007] Level 1: ≥99.5%

[0008] Level 2: ≥98% and <99.5%

[0009] Level 3: ≥95% and <98%

[0010] Level 4: <95%

[0011] The levels are measured at intervals of 0.5 m 2 / l is used to report the coverage rate. For example: 8m 2 / l level 1, or 9.5m 2 / l under level 2.

[0012] It is well known that factors contributing to good hiding power are firstly the solids content (determined in particular by the ratio of pigments, fillers and binders in the formulation) and the density of the coating composition. This is important because less paint with a high solids content must be applied than in the case of a paint with a lower solids content in order to achieve the desired layer thickness of the dry paint film.

[0013] In order to incorporate pigments and fillers into liquid media and to set the necessary particle size distribution, high mechanical forces are required. However, pigments and fillers often re-agglomerate or flocculate after the dispersion process, which defeats the dispersing effect and leads to serious performance problems, such as lack of color strength, lack of hiding power and contrast; loss of gloss, viscosity changes during storage, or sedimentation problems in wet paint.

[0014] Wetting and dispersing additives are often used for reliable dispersion and stabilization of pigments in coating systems. Wetting and dispersing additives act as interfacial substances, wet and cover the surface of the particles to be dispersed, reduce the viscosity of the mixtures to be dispersed, and stabilize these mixtures to avoid undesirable reagglomeration or flocculation of the particles.

[0015] The prior art discloses, for example, polymeric wetting agents and dispersants which contain firstly groups with pigment affinity, such as carboxyl, amino or phenyl functional groups, and secondly side chains which are soluble in the medium. The groups with pigment affinity ideally have a rapid orientation to the surface of the pigment and have high performance thereon. The side chains ensure compatibility with the dispersion medium or paint medium and steric stabilization of the dispersed phase.

[0016] EP 1 486 524 A1 describes the preparation of epoxy-amine adducts and their salts and their use as dispersants. These are obtainable by reaction of monofunctional or polyfunctional aromatic epoxides with polyoxyalkylene monoamines.

[0017] EP 1 745 104 A1 discloses comb-type polyetheralkanolamines as dispersants for inks and printing inks.

[0018] WO 2016 / 059066 describes comb copolymers based on epoxy-amine adducts.

[0019] Equally important for achieving the desired coating properties is the rheological properties of the coating composition. Therefore, the setting of the rheological properties of the coating composition is particularly important. The rheological properties are defined by the coating method to be adopted (e.g. spraying, roller coating, low coating, brushing or printing methods) and are ensured by the selection of the formulation.

[0020] Typically, rheological properties are measured over a wide range of shear rates. As is well known, high shear rates reflect tendencies such as spray or brush resistance and spray formation, while low shear rates reflect e.g. running characteristics and paint finish.

[0021] However, the predefined rheological properties often change during storage, so that the coating composition is no longer suitable for a particular coating method.

[0022] Some publications also mention biosurfactants as dispersants, defoamers, wetting agents or emulsifiers in paints and coatings. Known representatives of these biosurfactants are rhamnolipids and sophorolipids. These lipids are currently produced using wild-type isolates of various yeasts, especially Candida bombicola.

[0023] EP 3 006 505 describes, for example, a coating composition comprising a dispersion consisting of a binder, a biocide and a biosurfactant consisting of rhamnolipids and sophorolipids. EP 2 847 285 discloses a similar composition, in which an isothiazolinone biocide is added in particular. Both documents disclose the synergistic biocidal action of rhamnolipids and sophorolipids with biocides.

[0024] It would be desirable to identify materials that increase the coverage of the coating composition without changing the filler level or non-volatile content of the coating composition. It would also be desirable if the coating properties of the coating composition were maintained as much as possible after storage.

[0025] Coating and coating method will be used as synonyms.

[0026] It has now been found that, surprisingly, the use of rhamnolipids and / or sophorolipids for increasing the coverage of coating compositions is suitable without changing the amount of pigments, fillers and other non-volatile components. It has also been found, completely surprisingly, that the inventive use of rhamnolipids and / or sophorolipids leads to a rheological profile after storage that has a smaller variance from the set ideal rheological profile compared to comparable commercially available coating compositions. Thus, the usability of the coating composition according to the invention for an ideal coating is maintained.

[0027] This difference in rheological properties is quantified by measuring the viscosity of the coating composition before and after storage at a specific shear rate. In the paint industry, viscosity values ​​at shear rates of 1 / sec, 100 / sec and 1000 / sec before storage (e.g. one day after preparation of the coating composition) and after storage (e.g. one week after preparation of the coating composition) are often used to describe the coating properties of the coating composition. The greater the value of the set viscosity ratio, the greater the difference from the set ideal rheological properties.

[0028] The coating composition is preferably a preparation for various coating fields, which is applied to a substrate to be coated by a coating method such as spraying, dipping, rolling, pouring or brushing and various printing methods.

[0029] Examples of coatings in the context of the invention are lacquers, paints, printing inks and other coatings, such as solvent-borne or aqueous and solvent-free coatings, powder coatings, UV-curable coatings, low-solids, medium-solids and high-solids, automotive coatings, wood coatings, stoving coatings, 2-component coatings, metallic coatings, toner compositions. In "Bodo Müller, Ulrich Poth, Lackformulierung und Lackrezeptur, Lehrbuch für Ausbildung und Praxis [Coating Formulations and Coating Compositions, Training and Practice Textbook], Vincentz Verlag, Hanover (2003), 73-1996" and "PG Garrat, Further examples of coatings are given in "[Radiation Curing], Vincent Verlag, Hanover (1996)".

[0030] Coating and coating composition are used as synonyms.

[0031] The paints and coatings are interior paints, exterior paints, architectural paints, floor coatings, wood coatings, industrial paints, automotive OEM (original equipment manufacturer) or refinish paints, primers, primer-surfacers, basecoats and topcoats.

[0032] Examples of printing inks and / or printing varnishes in the present invention are solvent-based or aqueous printing inks, flexographic printing inks, gravure printing inks, letterpress or relief printing inks, offset printing inks, lithographic printing inks, printing inks for packaging printing, screen printing inks, printing inks such as printing inks for inkjet printers, inkjet inks, printing varnishes such as overprint varnishes. More printing ink and / or printing varnish formulations are given in "EW Flick, Printing Ink and Overprint Varnish Formulations-Recent Developments, Noyes Publications, Park Ridge NJ, (1990)" and subsequent editions.

[0033] The coating composition preferably comprises a solid selected from fillers, pigments, dyes, fluorescent brighteners, ceramic materials, magnetic materials.

[0034] Examples of pigments are those selected from inorganic pigments, such as carbon black; titanium dioxide; zinc oxide; Prussian blue; iron oxides; cadmium sulfides; chromium pigments, such as chromates; molybdates; and mixed chromates and sulfates of lead, zinc, barium, calcium and mixtures thereof. Further examples of inorganic pigments are described in the book "H. Endriss, Aktuelle anorganische Bunt-Pigmente [Current Inorganic Colored Pigments], Vincentz Verlag, Hannover (1997)".

[0035] Examples of organic pigments are those selected from azo, diazo, condensed azo, naphthol, metal complex, thioindigo, indanthrone, isoindanthrone, anthranthrone, anthraquinone, isodibenzanthrone, triphendioxazine, quinacridone, perylene, diketopyrrolopyrrole and phthalocyanine dyes. More examples of organic pigments are described in the book "W. Herbst, K. Hunger, Industrial Organic Pigments, VCH, Weinheim (1993)".

[0036] Examples of fillers are selected from talc, kaolin, silicas, barite and lime; ceramic materials such as aluminum oxides, silicates, zirconium oxides, titanium oxides, boron nitride, silicon nitride, boron carbide, mixed aluminum silicon nitrides and metal titanates; magnetic materials such as magnetic oxides of transition metals, such as iron oxides, cobalt-doped iron oxides and ferrites; metals such as iron, nickel, cobalt and alloys thereof.

[0037] Those skilled in the art will appreciate that such coating compositions may include other ingredients. As liquid media, they may contain organic solvents (e.g., acetates such as methyl acetate or ethyl acetate, hydrocarbons such as various boiling ranges of petroleum spirits, alcohols, ethers, glycols and glycol ethers) and / or water, as known in the art, depending on the binder used.

[0038] Conventional adhesives can be used. Preferably, alkyd resins, acrylates, styrene-acrylates, epoxy resins, polyvinyl acetates, polyesters or polyurethane adhesives can be used. Any type of curing is possible, for example by oxidative drying, physical drying, self-crosslinking, UV or electron beam curing or by baking crosslinking.

[0039] It is conceivable that the coating composition comprises further additives, such as preferably wetting agents, dispersing additives, rheological additives, leveling aids or defoamers.

[0040] Rhamnolipids and sophorolipids are surfactants that can be prepared by fermentation.

[0041] Rhamnolipids are composed of one to two rhamnose units and one to three mainly β-hydroxy fatty acids. The fatty acids can be saturated or unsaturated.

[0042] Variations in chain length and number (congeners) of the fatty acid moieties have been described in many publications (Howe et al., FEBS J. 2006; 273(22):5101-12; Abdel-Mawgoud et al., Appl Microbiol Biotechnol, 86, 2010; p. 1323-1336).

[0043] Miao et al., Journal of Surfactants and Detergents, 17(6), 2014; 1069-1080, describe the synthesis of dirhamnolipid ethyl ester by esterification with ethanol and the suitability of the ester as a nonionic surfactant.

[0044] WO 2001 010447 and EP 1 889 623 disclose pharmaceutical and cosmetic uses of rhamnolipids and short-chain rhamnolipids (C1-C6; methyl to hexyl esters, linear or branched), in particular for use in wound healing.

[0045] The rhamnolipid is preferably a compound of formula (I) or a salt thereof

[0046]

[0047] in

[0048] m=2, 1 or 0, especially 1 or 0,

[0049] n=1 or 0, especially 1,

[0050] R 6 and R 7 = independently identical or different organic radicals having 2 to 24, preferably 5 to 13 carbon atoms, which are especially optionally branched, optionally substituted, especially hydroxy-substituted, optionally unsaturated, especially optionally monounsaturated, diunsaturated or triunsaturated alkyl, preferably selected from pentenyl, heptenyl, nonenyl, undecenyl and tridecenyl and (CH2) x -CH3, wherein x=1 to 23, preferably 4 to 12.

[0051] Preferably, the mixed composition of rhamnolipids contains >90% diRL.

[0052] Preferably, the mixed composition of rhamnolipids contains:

[0053] 51 wt % to 95 wt % of diRL-C10C10, and

[0054] 0.5 to 9 wt% mono RL-C10C10, wherein the weight percentages are based on the sum of all rhamnolipids present, provided that the weight ratio of di-rhamnolipid to mono-rhamnolipid is greater than 91:9, preferably greater than 97:3, more preferably greater than 98:2.

[0055] For the use according to the invention, preference is given to using rhamnolipid mixtures which contain 0.5 to 15% by weight of di-RL-C10C12:1, the percentages by weight being based on the sum of all rhamnolipids present.

[0056] The sophorolipid is preferably a compound of formula (II) or (IIa)

[0057]

[0058] in

[0059] R 1 and R 2 are independently H or acetyl,

[0060] R 3 is H, methyl, ethyl or hexyl,

[0061] R 4 are independently saturated or unsaturated divalent branched or unbranched organic groups,

[0062] R 5 is H or methyl,

[0063] The condition is that the group R 4 and R 5 The total number of carbon atoms in the molecule does not exceed 29.

[0064] Rhamnolipids are available from Stepan (Northfield, IL, USA) under the name Natsurfact and from Evonik Operations GmbH under the name One gets.

[0065] Sophorolipids are available from Holiferm Limited (Manchester, UK) under the name HoneySurf and from Evonik Operations GmbH under the name SL ONE obtained.

[0066] Preferably, rhamnolipids and / or sophorolipids are used in a range of 0.01% to 10.0% by weight, more preferably 0.1% to 5.0% by weight, based on the total coating composition.

[0067] Preference is given to using rhamnolipids and sophorolipids of the general formulae (I), (II) and (IIa) to increase the storage stability of the coating composition.

[0068] The use of rhamnolipids and sophorolipids of the general formula (I), (II) and (IIa) is preferred in order to reduce the amount of coating composition used.

[0069] The present invention will be explained in detail below by means of working examples.

[0070] method

[0071] Determination of rheological properties and viscosity ratio

[0072] The rheological properties of the coating compositions were determined with the aid of a rotational viscometer (Euro Physics, Rheo 2000RC20). The measuring system used was a plate / cone system (45 mm, angle 1°, measuring temperature 25° C.).

[0073] The following shear rates and residence times were selected:

[0074] 0.1 to 10 s within 60 s -1

[0075] 10 to 90 seconds within 30 seconds -1

[0076] 100 to 1000s in 40s -1

[0077] 1000 to 10 000s in 40s -1

[0078] Use in 1s -1 , 100s -1 and 1000s -1 The difference is evaluated by the viscosity values ​​of the coating composition shown in the rheological properties before and after storage at a shear rate of . The viscosity ratio in % can be calculated as follows:

[0079] Viscosity ratio % = (viscosity, 1 week after preparation at 50°C / viscosity one day after preparation) * 100

[0080] The greater the numerical value of the viscosity ratio, the greater the difference between the rheological properties after storage and the set ideal rheological properties.

[0081] Coverage

[0082] The coverage of the coating composition is determined in the "Richtlinie zur Bestimmung des ", VdL-RL 09 from the Verband der deutschen Lackindustrie eV, July 2002 edition.

[0083] A substrate with a standardized surface of black and white fields (Form 2A from Leneta) was weighed. The paint was applied to the substrate with a wet film thickness of 150 μm, 200 μm and 240 μm by means of a film applicator. The freshly coated substrate was weighed again and then dried for 24 hours at 23° C. and 50% air humidity. Thereafter, the contrast of all drawdowns was measured with a Byk Gardner spectrophotometer with a glosstrap. For this purpose, measurements were taken at five measuring points, in each case in three black fields (Ys values) and in each case in three white fields (Yw values).

[0084] The contrast is determined by forming the quotient Ys / Yw*100[%] of the mean values ​​Yw and Ys. Then, at a contrast of 99.5%, taking into account the specific gravity of the varnish and the amount of varnish applied in each case, the value m 2 / l is used as the unit to determine the coverage. Example

[0085] 1. Preparation of coating composition

[0086] For performance evaluation, coating compositions CE1, E2 and E3 were prepared according to the data in Table 1. Comparative Example CE1 was prepared using the commercial dispersant Tego Dispers 747W.

[0087] First, items 1 to 5 were initially added and homogenized with a Dispermat (Dispermat CA from VMA-Getzmann GmbH) at 800 rpm for 5 minutes, then item 6 was added while stirring at 800 rpm and the mixture was stirred for 2 minutes. Items 7 to 11 were then added at 2500 rpm and the mixture was stirred for 30 minutes. Subsequently, the formulation was cooled by stirring at 500 rpm for 15 minutes. Items 12 to 14 were added while stirring at 2500 rpm.

[0088] Table 1

[0089]

[0090] 2. Technical testing

[0091] For the performance tests, the coating compositions CE1, E2 and E3 from Example 1 were tested for their rheological properties before and after storage and the coverage was determined.

[0092] 2.1 Coverage

[0093] Table 2 shows the coverage results.

[0094] Found that using conventional Dispers 747W compared to the original use of SL ONE or The coating composition of One achieved higher coverage with a contrast ratio of 99.5% (Grade 1).

[0095] Table 2: Coverage

[0096] Coating composition <![CDATA[Coverage at a contrast of 99.5% (m 2 / l) <!-- 8 -->]]> CE1 3.67 E2 5.25 E3 4.17

[0097] 2.2 Viscosity ratio

[0098] Table 3 shows the measured viscosities of the respective coating compositions before and after storage, and their viscosity ratios.

[0099] Found that using conventional Dispers 747W compared to the original use of SL ONE or The coating composition of One has a lower viscosity ratio at shear rates (1 / sec, 100 / sec, 1000 / sec). It can therefore be concluded that the coating composition according to the present invention maintains coating properties better than the comparative example during storage.

[0100] Table 3:

[0101]

Claims

1. Use of a rhamnolipid and / or a sophorolipid for increasing the coverage during storage of a coating composition and / or for maintaining coating properties during storage of a coating composition.

2. The use according to claim 1, characterized in that The coating composition is a paint and coating selected from the group consisting of interior paints, exterior paints, architectural paints, floor coatings, wood coatings, industrial paints, automotive OEM or repair paints, substrates, primer surfacers, primers and topcoats.

3. The use according to claim 1 or 2, characterized in that The coating composition comprises a solid selected from fillers, pigments, dyes, fluorescent brighteners, ceramic materials, and magnetic materials.

4. The use according to claim 1 or 2, characterized in that The coating composition comprises further additives.

5. The use according to claim 4, characterized in that The further additives are wetting agents, dispersing additives, rheological additives, leveling aids or defoamers.

6. The use according to claim 1 or 2, characterized in that The rhamnolipid is a compound of general formula (I) or a salt thereof in m=2, 1 or 0, n=1 or 0, R 6 and R 7 = independently identical or different organic groups having 2 to 24 carbon atoms.

7. The use according to claim 6, characterized in that m is 1 or 0.

8. The use according to claim 6, characterized in that n is 1.

9. The use according to claim 6, characterized in that R 6 and R 7 = independently identical or different organic groups having 5 to 13 carbon atoms.

10. The use according to claim 6, characterized in that R 6 and R 7 is an optionally branched, optionally substituted, or optionally unsaturated alkyl group.

11. The use according to claim 10, characterized in that R 6 and R 7 It is an alkyl group substituted with a hydroxy group.

12. The use according to claim 10, characterized in that R 6 and R 7 It is a monounsaturated, diunsaturated or triunsaturated alkyl group.

13. The use according to claim 6, characterized in that R 6 and R 7 Selected from pentenyl, heptenyl, nonenyl, undecenyl, tridecenyl and (CH2) x -CH3, wherein x=1 to 23.

14. The use according to claim 13, characterized in that x=4 to 12.

15. The use according to claim 1 or 2, characterized in that The rhamnolipids are mixed compositions with >90% di-rhamnolipids.

16. The use according to claim 1 or 2, characterized in that The rhamnolipid is a mixed composition comprising rhamnolipid, characterized in that the mixed composition contains 51 to 95 wt % of dirhamnolipid-C10C10, and 0.5 to 9 wt% of monorhamnolipid-C10C10, The weight percentages are based on the sum of all rhamnolipids present, with the proviso that the weight ratio of di-rhamnolipid to mono-rhamnolipid is greater than 91:

9.

17. The use according to claim 16, characterized in that The weight ratio of dirhamnolipid to monorhamnolipid is greater than 97:

3.

18. The use according to claim 16, characterized in that The weight ratio of dirhamnolipid to monorhamnolipid is greater than 98:

2.

19. The use according to claim 1 or 2, characterized in that The rhamnolipid is a mixed composition comprising rhamnolipids, characterized in that the mixed composition contains 0.5 wt % to 15 wt % of di-rhamnolipid-C10C12:1, wherein the weight percentage is based on the sum of all rhamnolipids present.

20. The use according to claim 1 or 2, characterized in that The sophorolipid is a compound of formula (II) or (IIa) in R 1 and R 2 are independently H or acetyl, R 3 is H, methyl, ethyl or hexyl, R 4 are independently saturated or unsaturated divalent branched or unbranched organic groups, R 5 is H or methyl, The condition is that R 4 and R 5 The total number of carbon atoms in the radical does not exceed 29.

21. The use according to claim 1 or 2, characterized in that The amount of the rhamnolipid and / or sophorolipid used is in the range of 0.01 wt % to 10.0 wt % based on the total coating composition.

22. The use according to claim 21, characterized in that The amount of the rhamnolipid and / or sophorolipid used is in the range of 0.1 wt % to 5.0 wt % based on the total coating composition.

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