Dispersant for producing aqueous pigment preparations

Abstract

The invention relates to the use of VOC-reduced vinyl-ether-based copolymer compositions for reducing the viscosity in coating compositions or in pigment pastes and / or for reducing the opacity of the coatings produced therefrom, which leads to a reduction in clouding effects and thus to the improvement in the visual appearance of a coating and the enhancement of potential effects of additives in a coating which have been impaired by the clouding.

Description

[0001] 202400041 Abroad 1

[0002] Dispersing agent for the production of aqueous pigment preparations

[0003] The invention relates to the use of VOC-reduced vinyl ether-based copolymer compositions for the production of aqueous pigment preparations.

[0004] Coatings are applied to surfaces for decorative and / or protective purposes. Many coating applications utilize formulations containing particles such as pigments and / or fillers.

[0005] Pigments are coloring substances that are dispersed insoluble form in the application medium. Application media include, for example, paints, varnishes, pigment preparations, printing inks, as well as organic solvents and other preparations into which the pigment is incorporated. Typically, the crude pigments produced during synthesis are milled or crushed before use; for example, so-called dry and wet milling processes are employed. However, small-diameter particles are particularly prone to agglomeration and therefore require stabilization.

[0006] Pigment stabilization is of great importance in the coatings industry, as pigments, being a key formulation component, determine the optical appearance and physicochemical properties of a coating. To ensure they can perform optimally within the coating, they must not only be stabilized against flocculation, but the rheology of the pigment-containing application media must also be adjusted to prevent settling and the resulting sediment.

[0007] Pigment preparations, pigment pastes and pigment concentrations are understood here as synonyms.

[0008] In the production of pigment pastes, dispersants or surfactants are used to physically stabilize the pigment particles in their finely divided form in an aqueous or aqueous / organic medium. To facilitate and improve the dispersion of solids in liquid media, dispersants are commonly employed. These surfactants promote the wetting of the solid particles to be dispersed and facilitate the breaking up of agglomerates. These dispersants also stabilize the resulting dispersions and prevent reagglomeration or flocculation of the solid particles. Dispersants are of particular importance, for example, for the dispersion of pigments in the production of printing inks, paints, and varnishes.

[0009] Wetting and dispersing agents facilitate the incorporation of pigments and fillers in the production of paints and coatings. These pigments and fillers are important formulation components that significantly determine the optical appearance and physicochemical properties of coatings. For optimal utilization, these solids must be evenly distributed in paints and coatings, and the distribution, once achieved, must be stabilized. Numerous problems can arise during the production and processing of aqueous pigment pastes and their subsequent use in the formulation of paints and printing inks:

[0010] • Difficult incorporation of pigments, poor wetting

[0011] • High viscosities of color pastes, paints and varnishes

[0012] • Sediment formation

[0013] • Vertical floating of pigments

[0014] • Horizontal floating of pigments

[0015] • Low gloss level

[0016] • Low coverage capacity

[0017] • Insufficient transparency

[0018] • Insufficient color intensity

[0019] • Poorly reproducible color tones, color migration

[0020] • Excessive runoff of paints.

[0021] Commercially available paint formulations are only monopigmented in some applications; more often, they consist of mixtures of two or more different pigments. The white pigment, usually titanium dioxide, is typically ground into the base color. The colored pigments very often originate from pigment concentrates, which have a higher concentration of pigment particles and are specifically used for coloring paints and varnishes.

[0022] When using pigments to color high-molecular-weight organic materials, high demands are placed on the pigments' application-related properties, such as high color strength, easy dispersibility, high chroma and purity of hue, and good lightfastness and weather resistance. Ideally, the pigments should be as universally applicable as possible for coloring various high-molecular-weight systems, such as plastics, as well as aqueous and solvent-based printing inks and varnishes. For both varnishes and printing inks, the trend is toward high pigment concentrations in the grinding stage; therefore, highly pigmented varnish and printing ink concentrates or millbases with low viscosity are required. Likewise, the viscosity of the finished varnish or printing ink must be suitable for the application.Printing inks require high transparency, while coating systems demand flawless recoatability and solvent resistance, as well as resistance to alkalis and acids. Particularly in the case of metallic coatings, high transparency and brilliant colors are essential. For coloring plastics, high bleed resistance, heat stability, and good dispersibility are required, which is reflected, for example, in high color strengths. Furthermore, the greatest possible versatility in various systems, such as aqueous and solvent-based systems, is desirable.

[0023] Many material surfaces, especially wooden substrates, are severely attacked and damaged by UV radiation. Attempts are made to counteract this by adding organic light stabilizers (radical scavengers / UV absorbers) or inorganic materials, such as transparent iron oxides. The advantage of using inorganic substances is that, compared to organic light stabilizers, they do not decompose or break down and are therefore permanently effective. Furthermore, organic light stabilizers often have harmful and environmentally hazardous properties. The protection against UV radiation provided by inorganic substances is achieved through reflection and absorption.If inorganic materials are used to avoid organic-based UV absorbers, the problem arises that the transparency or colorlessness of the coating is increasingly impaired when the substances are used in concentrations that provide sufficient UV protection. The coating appears cloudy when titanium dioxide, silicon dioxide, etc., are used, or colored when colored, such as yellow or red transparent iron oxides, are used.

[0024] Furthermore, it would also be desirable to reduce the volatile organic content (VOC) in paints and, ultimately, in pigment preparations. The German Chemicals Regulation on the Limitation of Emissions of Volatile Organic Compounds (VOCs) by Restricting the Marketing of Solvent-Based Paints and Varnishes (ChemVOCFarbV) regulates the use of VOCs in architectural paints and vehicle coatings. This regulation has triggered a general trend in the paint and coatings industry, so that many paint manufacturers are now also striving to reduce VOCs. For example, Commission Decision 202400041 of 28 May 2014 establishing the environmental criteria for the award of the EU Ecolabel for interior and exterior paints and coatings sets upper limits of 10 g / L VOC and 30 g / L SVOC for matte white interior wall paints.

[0025] VOC components, especially those that are harmful to health, particularly carcinogenic, mutagenic, or reprotoxic substances, have received considerable attention in the past and are often the target of regulatory and reduction efforts. Such components can be listed, for example, as Substances of Very High Concern (SVHCs). Regarding SVHCs, the REACH Regulation (EC) No. 1907 / 2006 describes how chemical substances with particularly hazardous properties (serious effects on human health and the environment) are to be identified. The identification process is carried out by the European Chemicals Agency (ECHA). Identified substances are classified as SVHCs (Substances of Very High Concern) and listed in Annex XIV of the REACH Regulation. These substances are therefore subject to authorization.Manufacturers, importers, and downstream users must demonstrate during the authorization process that they are competent in handling these substances and that a substitution assessment has been conducted. Furthermore, Annex XVII of the REACH Regulation contains a list of restricted substances; these substances are subject to a prohibition or restriction regarding their manufacture and placing on the market. Finally, potential SVHC candidates can be included in a list of substances of very high concern (SVHCs) under the REACH Regulation, which is eligible for authorization. Inclusion on this list immediately triggers legal obligations for the manufacture, import, or use of the SVHC candidates.

[0026] For example, formaldehyde (CAS 50-00-0), a prototypical VOC component, has been listed in Annex XVII since July 27, 2023. Acetaldehyde (CAS 75-07-0) is not yet included in the list of potential SVHC candidates. However, due to the GHS (Globally Harmonized System of Classification, Labelling and Packaging of Chemicals), its inclusion in the SVHC candidate list is expected in the medium term.

[0027] Another exemplary piece of legislation aimed at reducing emissions of harmful VOCs is California Proposition 65 from the state of California in the USA. This labeling law aims to protect drinking water sources from toxic substances. California Proposition 65 stipulates that substances classified as carcinogenic, mutagenic, or toxic to reproduction may not be released into the environment if there is a risk of contaminating drinking water sources. Furthermore, individuals must be explicitly warned before exposure to such substances. The list of chemicals 202400041 Foreign 5 according to California Proposition 65 includes both acetaldehyde (CAS 75-07-0, since April 1, 1988) and formaldehyde (CAS 50-00-0, January 1, 1988).

[0028] Therefore, there remains a need to reduce volatile organic compounds, such as acetaldehyde and formaldehyde.

[0029] Vinyl ethers are known to be sensitive to ether cleavage at acidic and neutral pH values. For this reason, vinyl ethers are often used in organic synthesis as protecting groups for the corresponding alcohols (Vladimir V. Voronin et al., Examining the vinyl moiety as a protecting group for hydroxyl (-OH) functionality under basic conditions, Org. Chem. Front. 2020, 7, 1334–1342). Cleavage of the vinyl protecting group yields vinyl alcohol, which immediately tautomerizes to acetaldehyde. Even under optimal reaction conditions, this ether cleavage cannot be completely avoided during the radical polymerization of vinyl ethers, as the polymerization typically does not occur in the basic pH range where vinyl ethers would be stable. Therefore, the reaction always involves cleavage of the vinyl ether, producing acetaldehyde as a byproduct.Acetaldehyde can cause cancer and therefore, even at a concentration in the product of > 1000 ppm, leads to a classification as carcinogenic category 1 B with H350 (may cause cancer).

[0030] Prior art includes DE 100 17667 A1 and EP 0736553 A2, which describe such vinyl ether-based copolymer compositions and their use. DE 100 17667 A1 discloses that VOC-free pigment concentrates can be produced by using copolymers with unsaturated dicarboxylic acid derivatives and oxyalkylene glycol alkenyl ethers or polyalkylene oxide alkenyl ethers, as described in EP 0736553 A2. However, the inventors were able to demonstrate that such copolymers contain aldehydes. Reference is made to the comparative examples provided. From DE 100 17 667 A1 it is also known that by using copolymers with unsaturated dicarboxylic acid derivatives and oxyalkylene glycol alkenyl ethers or polyalkylene oxide alkenyl ethers according to EP 0 736 553 A2 the viscosity can be reduced and that the visual assessment of the transparency was rated as very good.Visual assessment is known to be subject to individual inaccuracies.

[0031] It is therefore desirable to propose a dispersing agent for the dispersion of pigments, with the aim in particular of further increasing the viscosity reduction of the pigment pastes and reducing the opacity of coatings produced therefrom, and without at least one other disadvantage known from the prior art. 202400041 Foreign 6

[0032] Based on the teaching of the unpublished European patent application EP23165127.4, filed on 29.03.2023, the present invention proposes the use of VOC-reduced vinyl ether-based copolymer compositions to lower the viscosity in coating compositions or pigment pastes and / or to reduce the opacity of the coatings produced therefrom, which leads to a reduction of haze effects and thus to an improvement in the optical appearance of a coating as well as to an increase in any effects of additives in a coating which were impaired by the haze.

[0033] Surprisingly, it was found that the use of the VOC-reduced vinyl ether-based copolymer compositions produced according to the teachings of EP23165127.4, as described in the invention, is suitable for increasing the viscosity reduction of the pigment pastes. Lower viscosity results in a higher pigment input for the same energy input, which reduces the time required for the production of pigment pastes and can therefore significantly reduce costs.

[0034] Completely unexpectedly, the viscosity reduction of the pigment paste could be achieved using copolymers similar to DE 100 17 667 A1, whereby the VOC content of the copolymers, in particular the content of volatile aldehydes, was reduced, according to a method according to the not yet published EP23165127.4.

[0035] VOC is the English abbreviation for Volatile Organic Compounds and refers to the group of volatile organic compounds.

[0036] Particularly surprising is the reduction in opacity of the resulting coatings. While the advantages initially lie primarily in the visual appearance, especially in metallic / basecoat systems, for example, opacity also plays a significant role when using expensive, special, transparent pigments. In such cases, the goal is to fully realize the potential of these pigments in terms of color brilliance and transparency. Any clouding would impair this effect.

[0037] Even with wood varnishes, especially clear varnishes, cloudiness would obscure the high-quality wood substrate. Pigments used to protect against UV radiation would also be unable to fully develop their effect due to cloudiness. 202400041 Abroad 7

[0038] The lower the opacity of coatings with dispersion clearcoats, the higher the transparency of these coatings. Therefore, the lowest possible opacity is typically sought when using highly transparent pigments. Low opacity means that the highly transparent pigments are particularly well dispersed in the dispersion clearcoat, and the average particle size of agglomerates of such pigments hardly exceeds 0.1 pm. At average particle sizes of less than 0.1 pm, highly transparent iron oxide pigments no longer scatter visible light and are therefore perceived as translucent. This property is relevant, among other things, for wood stains, effect coatings, and for coating formulations with a high desired transparency, such as solid-color topcoats, basecoats, metallic paints, wood stains, effect coatings, and for coloring transparent plastic coatings.

[0039] Preferably, the VOC-reduced vinyl ether-based copolymer composition is a conventional water-based vinyl ether-based copolymer composition in which the content of volatile aldehydes, preferably formaldehyde, acetaldehyde, propylaldehyde, and especially acetaldehyde, has been reduced.

[0040] Preferably, the conventional water-based vinyl ether-based copolymer composition was subjected to a process according to the unpublished European patent application EP23165127.4.

[0041] Preferably, the VOC-reduced vinyl ether-based copolymer composition is obtainable by a process according to the unpublished European patent application EP23165127.4, wherein at least one of the steps a) oxidation of the acetaldehyde in the vinyl ether-based copolymer composition, b) reduction of the acetaldehyde in the vinyl ether-based copolymer composition and / or c) reduction and oxidation of the acetaldehyde in the vinyl ether-based copolymer composition was carried out.

[0042] Preferably, the VOC-reduced vinyl ether-based copolymer composition comprises less than 600 ppm acetaldehyde, preferably less than 400 ppm acetaldehyde, particularly preferably less than 200 ppm acetaldehyde, even more preferably less than 100 ppm acetaldehyde, preferably less than 60 ppm acetaldehyde.

[0043] Preferably, the VOC-reduced vinyl ether-based copolymer composition comprises less than 100 ppm formaldehyde, preferably less than 50 ppm formaldehyde, particularly preferably less than 10 ppm formaldehyde, and even more preferably less than 5 ppm formaldehyde.

[0044] Surprisingly, it was found that the use of acetaldehyde-reduced copolymer compositions, as described in the unpublished European patent application EP23165127.4, preferentially leads to a viscosity-reducing effect. It is assumed, without being bound to any theory, that acetaldehyde has a detrimental effect on the viscosity-reducing property of the copolymer composition, a fact previously unknown to those skilled in the art.

[0045] The coating compositions preferably consist of paints and varnishes, selected from interior wall paints, facade paints, building paints, floor coatings, wood varnishes, industrial varnishes, automotive OEM or repair paints, primers, fillers, basecoats and topcoats.

[0046] It is also preferred that the coating composition includes solids selected from fillers, pigments, dyes, optical brighteners, ceramic materials, and magnetic materials.

[0047] In addition, the coating composition preferably contains further additives, preferably wetting agents, dispersing additives, rheology additives, leveling agents or defoamers.

[0048] The invention is preferably used in pigment concentrates, color pastes, pigment pastes or ground materials.

[0049] The VOC-reduced vinyl ether-based copolymer is preferably used in a range of 0.01 wt.% to 25.0 wt.%, particularly preferably 0.1 wt.% to 15.0 wt.%, based on the total pigment paste. 202400041 Foreign 9

[0050] Preferably, the VOC-reduced vinyl ether-based copolymer is used in a range of 0.01 wt.% to 25.0 wt.%, particularly preferably 0.1 wt.% to 10.0 wt.%, based on the total coating composition. The following examples describe the present invention by way of example, without limiting the invention, the scope of which is evident from the entire description and the claims, to the embodiments mentioned in the examples.

[0051] 202400041 Abroad 10

[0052] materials

[0053] The copolymer compositions A to E are commercially available, vinyl ether-based copolymers, as described in the unpublished European patent application EP 23165127.4:

[0054] • Copolymer compositions A: Copolymer A is a polycarboxy ether based on the monomeric building blocks maleic anhydride and vinyl polyether Pluriol A 1190 V in a concentration of 49.5 wt% in aqueous solution, analogous to a copolymer composition described in Example No. 6, table on page 13 of DE 100 17 667 A1 or EP0736553A2.

[0055] • Copolymer compositions B: Copolymer B is a polycarboxy ether based on the monomeric building blocks acrylic acid, 3-hydroxypropyl acrylate and vinyl polyether Pluriol A 1190 V at a concentration of 45 wt% in aqueous solution.

[0056] • Copolymer compositions C: Copolymer C is a polycarboxy ether based on the monomeric building blocks acrylic acid, vinyl polyether Pluriol A 1190 V and vinyl polyether Pluriol A 3090 V at a concentration of 46 wt% in aqueous solution.

[0057] • Copolymer compositions D: Copolymer D is a polycarboxy ether based on the monomeric building blocks maleic anhydride, 4-hydroxybutyl vinyl ether and an ester obtained from maleic anhydride and MPEG 2000 at a concentration of 47 wt% in aqueous solution.

[0058] • Copolymer compositions E: Copolymer E is a polycarboxy ether based on the monomeric building blocks acrylic acid and vinyl polyether Pluriol A 3090 V at a concentration of 40 wt% in aqueous solution.

[0059] Biocide: Parmetol K6 (VINK Chemicals)

[0060] Pigment: Sicotrans Yellow L 1916 (Sun Chemical)

[0061] Pigment: Sicotrans Red L 2816 (Sun Chemical)

[0062] Neocryl XK-190 (Covestro)

[0063] Texanol (Eastman) 202400041 Foreign 1 1

[0064] Measurement methods

[0065] Measurement of Acetaldehyde Content: To quantify acetaldehyde, it is converted by reaction with 2,4-dinitrophenylhydrazine and subsequently detected as a hydrazone by HPLC (high-performance liquid chromatography). First, the analyte is dissolved in the eluent solution, which is a mixture of 55% acetonitrile and 45% 0.05M KH₂PO₄ buffer at pH 2.5. Then, 2,4-dinitrophenylhydrazine is added, and the reaction mixture is stirred for 2 hours. Afterward, the sample is injected into the HPLC instrument, which is equipped with a Nucleosil C18 100-5 column. Detection is performed using UV light at a wavelength of 360 nm. For quantification, calibration is carried out using five standards with known acetaldehyde concentrations.

[0066] 202400041 Abroad 12

[0067] Application-related testing

[0068] 1. Selection of copolymer compositions according to the unpublished European patent application EP23165127.4

[0069] First, a selection of the copolymer compositions listed under "Materials" was made. These copolymer compositions were subjected to various aldehyde reduction processes according to the unpublished European patent application EP23165127.4. The process names were taken from the unpublished European patent application EP23165127.4. Table 1 shows the selection of copolymer compositions, the aldehyde reduction processes used, and the acetaldehyde content.

[0070] Table 1

[0071] 2. Preparation of aqueous pigment preparations

[0072] To prepare the aqueous pigment preparations, the respective copolymer composition was placed in a 250 mL wide-mouth glass vial with the other liquid components according to the specifications in Table 2. It was briefly homogenized by hand using a metal spatula, and then the pigment from Table 2 was added by weight. Dispersal was carried out after adding 200 g of glass beads (d = 2.5–2.8 mm) per 100 g of pigment preparation in a Lau Scandex shaker for 3 hours. After sieving the glass beads, the pigment preparations were left to stand for 24 hours at room temperature. 02400041 Abroad 13 Table 2

[0073] 202400041 Abroad 14

[0074] 3. Viscosity measurements of the pigment preparations

[0075] The rheometer from Haake, type RheoStress, was used for the rheological viscosity profiles.

[0076] 1. Measurement parameters: Cone / plate C35 / 2°, 23°C, multiple measurement points in the range of 1–1000 1 / s. The viscosity was evaluated at 100 1 / s. The viscosities of the various

[0077] Pigment preparations are shown in Table 3.

[0078] Table 3: Viscosity values ​​of the pigment preparations

[0079] 202400041 Abroad 15

[0080] 4. Production of dispersion clear varnishes and determination of opacity

[0081] To produce the dispersion clearcoats, 20 g of clearcoat (a mixture of Neocryl XK 190 (97 wt%) and Texanol (3 wt%)) and 3.6 g each of the pigment preparations from Table 2 were used. First, the basecoat and the pigment preparation were weighed into a 60 ml PP screw-top container. Using the Hauschild Speed ​​Mixer DAC 150.1 FVZ, the basecoat and the pigment preparation were mixed and homogenized for 1 minute at 2,000 rpm. The resulting dispersion clearcoats were then applied to a contrast card using a 100 µm spiral doctor blade from Leneta. The opacity of the dried clearcoat applications was determined using an X-Rite Ci62 spectrophotometer. Table 4 shows the opacities of the clearcoat dispersion coatings.

[0082] Table 4

[0083] 5. Evaluation

[0084] The following should be noted when evaluating the results:

[0085] The lower the viscosity of the pigment preparation, the more fluid and processable it becomes, and the more efficiently the pigments can be dispersed at high pigment concentrations in the preparations. Therefore, low viscosity values ​​are desirable. Furthermore, the viscosity of the pigment preparation after storage (4 weeks, 50 °C) should hardly differ from the value at room temperature (immediately after preparation). The smaller the deviation from high viscosity values, the more efficient the stabilizing effect of the wetting and dispersing additive. A decrease in viscosity is also acceptable and is explained by subsequent wetting effects. However, a very strong increase in viscosity indicates an unstable pigment preparation, which should be well known to those skilled in the art.

[0086] The lower the opacity of coatings with dispersion clearcoats, the higher the transparency of these coatings. Therefore, the lowest possible opacity is typically sought when using highly transparent pigments. Low opacity means that the highly transparent pigments are particularly well dispersed in the dispersion clearcoat, and the average particle size of agglomerates of such pigments hardly exceeds 0.1 pm. At average particle sizes of less than 0.1 pm, highly transparent iron oxide pigments no longer scatter visible light and are therefore perceived as translucent. This property is relevant, among other things, for wood stains, effect coatings, and for coating formulations with a high desired transparency, such as solid-color topcoats, basecoats, metallic paints, wood stains, effect coatings, and for coloring transparent plastic coatings.

[0087] Table 3: Pigment preparation comparison examples VGA-Y and VGA-R, based on the monomeric building blocks maleic anhydride and vinyl polyether, exhibit low viscosities of 240 and 120 mPas, respectively, for Sicotrans Yellow L 1916 and Sicotrans Red L 2816. In contrast, pigment preparation comparison examples VGB-Y, VGE-Y, VGB-R, and VGE-R, containing acrylic acid and acrylates as monomeric building blocks, show viscosities of a comparably high order of magnitude.

[0088] Copolymer composition A

[0089] Surprisingly, it has now been found that the viscosity-reducing effect of copolymer composition A is further enhanced by various processes for reducing the acetaldehyde content disclosed in the as yet unpublished European patent application EP23165127.4. For example, a process for the oxidative removal of aldehydes in copolymer composition A (Table 1, DA3) has, as expected, a positive effect on the aldehyde content (reduction of acetaldehyde from 740 to 571 ppm), and surprisingly, it was also found that the viscosity of the pigment preparations is significantly reduced (Table 3, DA3-Y and DA3-R). A similar observation is provided by a process for the reductive removal of aldehydes (Table 1, DA2) with a reduction of the proportion of acetaldehyde from 740 to 103 ppm, surprisingly also accompanied by a further reduction in viscosity (Table 3, DA2-Y and DA2-R).Finally, a third method for reducing aldehydes via pH shift in a Carnizzaro-type reaction not only successfully reduced acetaldehyde from 740 ppm to 53 ppm (Table 1, DA1) but also, surprisingly, resulted in a significant reduction in viscosity (Table 3, DA2-Y and DA2-R). It was thus demonstrated that reducing the concentration of acetaldehyde in copolymer composition A via different chemical pathways consistently leads to a significantly reduced viscosity compared to the original copolymer composition A.

[0090] Copolymer compositions B and E

[0091] The same effect can be observed with dispersing additives based on acrylates and vinyl polyethers (copolymer compositions B and E). Here, both a reductive process (Table 1, DB) and a pH-shift process following a Carnizzaro reaction (Table 1, DE) demonstrate, for example, a reduction in the aldehyde content of the copolymer compositions as well as a moderately improved viscosity reduction (Table 3, DB-R) and a significantly improved viscosity reduction, respectively (Table 3, entries DB-Y, DE-Y and DE-R).

[0092] Opacity reduction

[0093] In addition to the improved viscosity reduction, an improved opacity reduction was also surprisingly found for the various acetaldehyde-reduced copolymer compositions.

[0094] Here, copolymer A for the pH shift and the reductive process for aldehyde removal (Table 1, DA1 and DA2) shows a pronounced reduction in opacity (Table 4, entries LackDA1-Y, LackDA2-Y, LackDA1-R, LackDA2-R), while in the case of the oxidative process (Table 1, DA3) a still significant reduction in opacity can be observed (Table 4, LackDA3-Y and LackDA3-R).

[0095] This effect has also been demonstrated for copolymer B, where, after a reductive process (Table 1, DB), both a reduction in aldehyde content and a reduction in opacity were achieved with both tested pigments Sicotrans Yellow L 1916 and Sicotrans Red L 2816 (Table 4, LackDE-Y and LackDE-R).

Claims

202400041 Abroad 19 Patent claims 1. Use of VOC-reduced vinyl ether-based copolymer compositions to lower the viscosity in coating compositions or pigment pastes and / or to reduce the opacity of the coatings produced therefrom, which leads to a reduction in haze effects and thus to an improvement in the optical appearance of a coating as well as to an increase in any effects of additives in a coating which were impaired by the haze.

2. Use according to claim 1, characterized in that the VOC-reduced vinyl ether-based copolymer composition is a conventional water-based vinyl ether-based copolymer composition in which the content of volatile aldehydes, preferably formaldehyde, acetaldehyde, propylaldehyde, particularly preferably acetaldehyde, has been reduced.

3. Use according to any of the preceding claims, characterized in that the VOC-reduced vinyl ether-based copolymer composition is obtainable by a process wherein at least one of the steps a) oxidation of the acetaldehyde in the vinyl ether-based copolymer composition, b) reduction of the acetaldehyde in the vinyl ether-based copolymer composition and / or c) reduction and oxidation of the acetaldehyde in the vinyl ether-based copolymer composition has been carried out.

4. Use according to any of the preceding claims, characterized in that the VOC-reduced vinyl ether-based copolymer composition comprises less than 600 ppm acetaldehyde, preferably less than 400 ppm acetaldehyde, particularly preferably less than 200 ppm acetaldehyde, even more preferably less than 100 ppm acetaldehyde, preferably less than 60 ppm acetaldehyde.

5. Use according to one of the preceding claims, characterized in that the VOC-reduced vinyl ether-based copolymer composition contains less than 202400041 Abroad 20 100 ppm formaldehyde, preferably less than 50 ppm formaldehyde, particularly preferably less than 10 ppm formaldehyde, even more preferably less than 5 ppm formaldehyde comprises 6. Use according to one of the aforementioned claims, characterized in that the coating compositions are paints and varnishes selected from interior wall paints, facade paints, building paints, floor coatings, wood varnishes, industrial varnishes, automotive OEM or repair varnishes, primers, fillers, basecoats and topcoats.

7. Use according to one of the preceding claims, characterized in that the coating composition comprises solids selected from fillers, pigments, dyes, optical brighteners, ceramic materials, magnetic materials.

8. Use according to one of the preceding claims, characterized in that the coating composition contains further additives, preferably wetting agents, dispersing additives, rheology additives, leveling agents or defoamers.

9. Use according to one of the preceding claims, characterized in that the use takes place in pigment concentrates, color pastes, pigment pastes or ground materials.

10. Use according to one of the preceding claims, characterized in that the VOC-reduced vinyl ether-based copolymer is used in a range of 0.01 wt.% to 25.0 wt.%, preferably 0.1 wt.% to 15.0 wt.%, based on the total pigment paste.

11. Use according to one of the preceding claims, characterized in that the VOC-reduced vinyl ether-based copolymer is used in a range of 0.01 wt.% to 25.0 wt.%, preferably 0.1 wt.% to 10.0 wt.%, based on the total coating composition.