Coating and composition for forming same

Abstract

The invention relates to a composition for forming a coating, more particularly a paint coating for the interior sector, comprising – at least one polymer binder, – a filler combination, – colour pigments and / or white pigments, and – water, wherein the filler combination (a) comprises at least two fillers which differ with respect to their morphology, and (b) has a total oil number to DIN EN ISO 787-5 of more than 40, preferably more than 50, more preferably more than 55, and wherein the pigment volume concentration (PVC) of the composition is less than 50%, preferably less than 44%, more preferably less than 36%. The invention further relates to a coating, more particularly a paint coating, formed from a composition according to the invention.

Description

[0001] Composition for forming a coating, coating

[0002] The invention relates to a composition for forming a coating, in particular a paint coating for interior use. Furthermore, the invention relates to a coating formed from a composition according to the invention.

[0003] State of the art

[0004] A coating, particularly a paint coating for interior use, is considered durable if it is resistant to soiling and exhibits high wet abrasion resistance. To achieve this, a binder-rich composition can be selected for the coating, whereby the binder is usually a polymer binder. In a binder-rich composition, the fillers contained therein are completely enclosed by the binder and thus firmly bound. A coating formed from the composition is therefore particularly stable against mechanical stress. In particular, the coating is wipeable and therefore easy to clean. The high binder content also means that dirt, especially in the form of liquids, cannot penetrate as easily, so that the coating retains its attractive appearance for longer.

[0005] A disadvantage, however, is that coatings made from binder-rich compositions have a high degree of gloss, so that matting agents must be added to achieve a matte finish. The proportion of matting agent required increases with the proportion of binder. However, as the proportion of matting agent increases, the viscosity of the composition also increases, making it more difficult to process. In addition, a coating with a high proportion of binder and therefore also matting agent is prone to the so-called "writing effect". This effect occurs primarily, but not exclusively, with matte coatings and is caused by the fact that the color pigments are not completely enveloped by the binder and are therefore not protected. If the surface is subjected to mechanical stress, the color pigments are shifted or even damaged, resulting in light, shiny abrasion marks.This effect is particularly noticeable with an intensely tinted coating. Therefore, the addition of matting agents is limited.

[0006] For low-gloss interior paint coatings, low-binder compositions are often used. The addition of matting agents can then generally be omitted. However, coatings made with low-binder compositions are less durable, more susceptible to dirt, and often not washable.

[0007] Achieving a coating, in particular a colored coating, that is particularly tough and resistant to soiling, but at the same time has a low gloss level and without a tendency to write, therefore represents a conflict of objectives that must be resolved. In addition, the "scuff resistance" should be increased. "Scuff resistance" is to be understood as the resistance of a coating, in particular a coating with a light color, to the formation of dark streaks. Common examples of dark streaks on surfaces are those caused by dark rubber soles. The reason for the streaking is exposed fillers or pigments on the surface, which give the surface a certain roughness. The aim is therefore to smooth the surface without increasing the gloss level of the surface. The present invention is concerned with this or these problems. To solve the problem or problems,The composition with the features of claim 1 is proposed for these purposes. Advantageous developments of the invention are set forth in the subclaims. Furthermore, a coating formed from a composition according to the invention is specified.

[0008] Disclosure of the invention

[0009] The invention relates to a composition for forming a coating, in particular a paint coating for interior use. This composition contains: at least one polymer binder, a filler combination,

[0010] Color and / or white pigments and

[0011] Water, wherein the filler combination (a) comprises at least two fillers which differ in terms of their morphology, and (b) has a total oil number according to DIN EN ISO 787-5 above 40, preferably above 50, furthermore preferably above 55, and wherein the pigment volume concentration (PVK) of the composition is less than 50%, preferably less than 44%, furthermore preferably less than 36%.

[0012] The proposed composition contains a filler combination with at least two fillers that differ in terms of their morphology. This means that morphologically divergent fillers are used. The more different and irregular the shape of the fillers, the larger the gaps and cavities remaining between the fillers. The goal is to achieve the most incomplete packing of fillers in the composition so that the gaps can be filled with binder. This means that the binder content can be increased. The increased binder content increases the resistance of a coating formed from the composition without simultaneously increasing the gloss level. This is because the binder does not accumulate on the surface of the coating, but settles into the gaps or cavities between the filler particles. In other words, it "hides" in the gaps and cavities.

[0013] The conflict of objectives described at the beginning is therefore solved in particular by the fact that the proposed composition contains a filler combination of at least two morphologically divergent fillers, so that large gaps remain between the fillers, which can be filled with binder.

[0014] The morphology of the fillers contained in the composition determines the oil absorption of an individual filler as well as the total oil absorption of all fillers. This is because the oil absorption of a filler contains information about the surface-to-volume ratio and thus about the morphology of the filler particles. In the technical glossary "Plasters and Coatings," the oil absorption is described as follows:

[0015] According to DIN EN ISO 787-5, the oil value is the quantity of linseed oil of a specified acid value added drop by drop that absorbs 100 g of pigment or filler when kneaded with a spatula until a coherent, putty-like, stiff paste is achieved (“netting point”).

[0016] The oil absorption of pigments or fillers is a frequently used parameter in the coatings and paints industry. It represents a measure of the binder requirement of the pigment or filler. The higher the oil absorption, the greater the binder requirement. Thus, the oil absorption influences various properties of coating films, such as wet abrasion resistance and the elasticity of a coating film (see also EN ISO 4618).

[0017] Another relevant parameter is the pigment volume concentration (PVC). The PVC is the ratio of the volume of pigments and fillers contained in the pigment to the total volume of non-volatile components, usually pigments, fillers, and binders. It is therefore an essential parameter for characterizing the volume ratio of pigment and filler to the binder. The lower the PVC, the higher the binder content. DIN EN ISO 4618:2015-01 can be used to determine the PVC. The following formula can be used to calculate the PVC:

[0018] PVK [%] — (^Vpigments + Vfillers / ^Vpigments + ^Vfillers + ^jVbinder) X 100

[0019] The claimed composition has a PVC of less than 50%, preferably less than 44%, and more preferably less than 36%. A PVC of 50%, especially 36%, is very low for a paint coating, especially an interior paint. This means that the binder content is high. Nevertheless, a coating formed from the specified composition is not glossy, which is due to the binder accumulating in the gaps between the fillers, where it then exerts its full binding power.

[0020] This is where the critical pigment volume concentration (CPVC) comes into play. In DIN EN ISO 4618:2015-01, the CPVC is defined as a specific PVC value at which the voids between the contacting solid particles of a coating are just barely filled with binder. Above the CPVC (supercritical range), the voids are therefore not completely filled with binder. Below the CPVC (subcritical range), all voids are completely filled with binder. In this case, a binder-rich, subcritical formulation is desired. This means that all voids are filled with binder and the fillers are firmly embedded in the binder. This increases the durability and abrasion resistance of a coating made from the composition. In addition, there is little binder on the coating surface, resulting in a low gloss level.

[0021] As already mentioned, the gloss level of a coating is usually determined by the polymer binder on the coating's surface. Although the binder content in the proposed composition is high, the binder does not accumulate on the surface of the coating, but rather "hides" in the gaps between the fillers. Thus, a microstructure remains on the surface of the coating, which scatters incident light, giving the surface a matte appearance.

[0022] Because the high binder content holds the filler particles together, the abrasion resistance of a coating formed from a composition according to the invention increases. This means that, unlike conventional matte paint coatings, the coating is not prone to the writing effect mentioned above.

[0023] The filler combination of the proposed composition preferably contains at least one mineral, inorganic filler whose oil absorption is 30-100, preferably 35-100, and more preferably 40-100. The oil absorption of an individual filler contained in the filler combination can therefore be below the total oil absorption of the filler combination. To achieve the total oil absorption, the filler must then be combined with a filler whose oil absorption is significantly higher than the specified total oil absorption. This is because the total oil absorption of all fillers (OI) is calculated as follows: (percentage OI1 * OI OO OO OO) + (percentage OI2 * OI OO OO) + (percentage OIn * OI OO OO) = total OI

[0024] Alternatively, the total oil absorption can be determined experimentally with an acceptable error tolerance by determining the oil absorption of the filler combination.

[0025] The oil absorption of a filler correlates with the specific surface area of ​​the individual filler particles. The specific surface area, in turn, is determined by the size and morphology of the filler particles. Fillers made of very small particles, with lamellar particle shapes and / or porous surfaces, exhibit a larger specific surface area and thus a higher oil absorption than fillers made of larger particles with a nodular, i.e., rounded-compact particle shape.

[0026] The high total oil content of the filler combination in the proposed composition suggests that it contains small, lamellar and / or porous filler particles. These promote the formation of gaps or cavities between the fillers, in which binder can accumulate.

[0027] Furthermore, the filler combination preferably contains at least one mineral, inorganic filler whose average particle size D50 is 1-30 pm, preferably 2-25 pm, further preferably 3-20 pm.

[0028] The mean particle size D50, also called the D50 value or median value, indicates the average particle size of a filler, such that the proportion of particles larger than the D50 value is equal to the proportion of particles smaller than the D50 value. These values ​​are preferably determined according to DIN ISO 9276-1:2004-09 (Presentation of particle size analysis results - Part 1: Graphic representation) and ISO 9276-2:2014-05 (Presentation of particle size analysis results - Part 2: Calculations of mean particle sizes / diameters and moments from particle size distributions). The Mastersizer 3000 from Malvern Instruments Limited can be used as the size determination instrument. However, these values ​​can usually also be easily obtained from a technical data sheet.

[0029] The at least one filler, whose oil index is 30-100, preferably 35-100, more preferably 40-100, and the at least one filler, whose average particle size D50 is 1-30 gm, preferably 2-25 gm, more preferably 3-20 gm, can be one and the same mineral, inorganic filler. This means that at least one other filler must be present with a higher oil index, preferably above 100, in order to achieve the required total oil index.

[0030] In a further development of the invention, it is therefore proposed that the filler combination contains at least one mineral, inorganic filler whose oil index is above 100 and whose average particle size D50 is 1-30 gm, preferably 1-20 gm, furthermore preferably 2-10 gm. This means that the at least one further filler does not differ from the previously mentioned filler in the size of its filler particles, but rather in its oil index. This means that the morphology of the at least one further filler is different, so that its oil index is above 100. The oil index of the at least one further filler must be selected to be high enough that the oil indexes of the fillers add up to a total oil index of > 40.

[0031] Suitable mineral, inorganic fillers include, in particular, all carbonate and silicate fillers. Furthermore, it is therefore recommended that the filler combination contain at least one carbonate and / or silicate filler. The deliberate addition of organic, especially synthetic organic, fillers is avoided for ecological reasons. Silicate fillers can be, for example, aurora, cristobalite, a phyllosilicate, talc, kaolin, and / or mica. Suitable carbonate fillers include, for example, calcite, marble, and / or dolomite.

[0032] The filler combination of the composition preferably contains at least one hard filler with a Mohs hardness > 5, preferably > 6, and at least one soft filler with a Mohs hardness < 5, preferably < 4. The at least one hard filler furthermore preferably has an oil number of 30-100 and an average particle size D50 of 1-30 μm. This means that the at least one hard filler is the filler of the filler combination with the corresponding oil number and the average particle size. The at least one soft filler preferably has an oil number above 100 and an average particle size D50 of 1-30 μm, so that in this case the soft filler is in particular the filler of the filler combination with the corresponding oil number and the average particle size.

[0033] A matting agent contained in the composition can also be considered a filler, although for ecological reasons, only mineral, inorganic matting agents are preferably used. The deliberate addition of organic, polymeric matting agents, such as polyethylene resins, polypropylene resins, polymethylureas, or wax additives such as polyethylene waxes, should be avoided.

[0034] Since the goal is a binder-rich subcritical formulation, it is further proposed that the proposed composition contain 3-41 wt.%, preferably 3-30 wt.%, and more preferably 4-25 wt.% fillers, based on the total weight of the starting materials. This includes all fillers present, and therefore also any mineral, inorganic matting agents. The combination of fillers must achieve the required total oil absorption and must not exceed the specified PKV. The proposed composition preferably contains 10-50 wt.%, preferably 15-40 wt.%, and more preferably 20-35 wt.% polymer binder, based on the total weight of the starting materials. The binder content results in a binder-rich composition.

[0035] Furthermore, the at least one polymer binder is preferably a polymer binder based on vinyl acetate / ethylene copolymers, copolymers based on vinylaromatics, in particular styrene, and acrylates and / or homopolymers or copolymers based on pure acrylates, in particular based on styrene-acrylate copolymers, and / or pure acrylates comprising homopolymers or copolymers of acrylates and / or methacrylates, optionally with acrylic and / or methacrylic acid as a comonomer building block. Also suitable and preferably used are self-crosslinking core-shell polymer binders based on acrylates, in particular pure acrylates. Particular preference is given to using homopolymers or copolymers based on pure acrylates and / or based on styrene-acrylate copolymers.

[0036] Advantageously, the at least one polymer binder is a polymer dispersion with a solids content of 30-65 wt.%, preferably 40-60 wt.%, and more preferably 40-55 wt.%, based on the total weight of the polymer dispersion. The use of a polymer dispersion facilitates the preparation of the composition.

[0037] In addition, the proposed composition may contain additives, for example, rheological additives, thickeners, pot and film preservatives, film-binding aids, biocides, defoamers, and / or fibers. The additives can be used, in particular, to control the processing properties of the composition. According to a preferred embodiment of the invention, the proposed composition contains, based on the total weight of the starting materials:

[0038] 10-50 wt.% polymer binder (solids content)

[0039] 1-8 wt.% inorganic fillers with an oil absorption > 100

[0040] 2-40 wt.% carbonate and / or silicate fillers with an oil absorption between 30 and 100,

[0041] 0-20 wt% additional fillers

[0042] 1-25 wt.% white and / or color pigments

[0043] 0.01-5.0 wt.% other additives

[0044] 10-50 wt% water

[0045] The proposed composition is particularly suitable for the formation of a paint coating for interior use. Compared to conventional interior paints, it exhibits high durability and low soiling resistance. Furthermore, matte paint coatings in intense colors can be formed that are significantly less prone to writing.

[0046] Since the advantages of a composition according to the invention become apparent in particular in a coating formed therefrom, a coating, in particular a colour coating, made from a composition according to the invention is further proposed.

[0047] The coating preferably has a wet abrasion resistance of wet abrasion class 1. This means that the coating is washable. The wet abrasion class can be determined using the standard DIN EN ISO 11998:2006-10 in conjunction with the standard DIN EN 13300 (November 2002). Furthermore, the coating preferably has a gloss level of < 10 GU, preferably < 8 GU, and further preferably < 7 GU. This means that the coating can be classified as "matt" or "dull matt" according to DIN EN 13300 (edition November 2002). The gloss level can be determined according to DIN EN ISO 2813:2014 (edition November 2002) at a measuring angle of 85°.

[0048] The advantages of a composition according to the invention and a coating formed therefrom are demonstrated below using a specific exemplary embodiment. This exemplary embodiment is particularly suitable for the formation of a paint coating for interior use.

[0049] Example

[0050] 50.0 wt.% polymer dispersion (solids content approx. 50%)

[0051] 3.0 wt.% inorganic fine filler (oil absorption > 150, D50 value = 6pm

[0052] 8.0 wt.% carbonate filler (oil absorption > 40, D50 value = 10 pm)

[0053] 6.0 wt.% silicate filler (oil absorption > 40, D50 value = 12 pm)

[0054] 10.0 wt.% white pigment rutile

[0055] 2.0 wt.% other additives (rheology additives, defoamers,

[0056] Preservatives, etc.)

[0057] 21.0% wt. water

[0058] 100% by weight

[0059] To prepare the composition, all starting materials were mixed homogeneously. The resulting composition had a PVC of 30%. The total oil absorption of all fillers was 75.

[0060] The composition prepared according to the exemplary embodiment was then evenly applied to several test cards using a slit doctor blade with a gap height of 300 μm and completely dried. The coatings produced in this way exhibited a gloss level of 7 GU, determined according to DIN EN ISO 2813:2014 (issue date 2015-02) and at a measurement angle of 85°. In the determination of wet abrasion resistance according to DIN EN ISO 11998:2006-10 in conjunction with DIN EN 13300 (November 2002), an average wet abrasion of 4 μm was determined (wet abrasion class 1). To determine soiling resistance and cleanability, various substances were applied to the coatings: red wine, ketchup, and coffee. After a contact time of five minutes, the substances were wiped off with a damp cloth and the coatings dried. The color difference delta E* was then determined and compared with values ​​of conventional interior paints.These had a significantly larger color difference delta E* compared to the coatings made from the composition according to the invention according to the exemplary embodiment.

[0061] The coatings produced from the inventive composition according to the exemplary embodiment were also tested for their resistance to scuffing and streaking. The test was conducted by visual inspection, i.e., subjective assessment. Here, too, the coatings made from the inventive composition performed better than conventional interior paints.

Claims

Patent claims 1. Composition for forming a coating, in particular a paint coating for interior use, containing at least one polymer binder, a filler combination, Color and / or white pigments and Water, wherein the filler combination (a) comprises at least two fillers which differ in terms of their morphology, and (b) has a total oil number according to DIN EN ISO 787-5 above 40, preferably above 50, furthermore preferably above 55, and wherein the pigment volume concentration (PVK) of the composition is less than 50%, preferably less than 44%, furthermore preferably less than 36%.

2. Composition according to claim 1, characterized in that the filler combination contains at least one mineral, inorganic filler whose oil number is 30-100, preferably 35-100, further preferably 40-100.

3. Composition according to claim 1 or 2, characterized in that the filler combination contains at least one mineral, inorganic filler whose average particle size D50 is 1-30 pm, preferably 2-25 pm, further preferably 3-20 pm.

4. Composition according to one of the preceding claims, characterized in that the filler combination contains at least one mineral, inorganic filler whose oil number is above 100 and whose average particle size D-50 is 1-30 pm, preferably 1-20 pm, further preferably 2-10 pm.

5. Composition according to one of the preceding claims, characterized in that the filler combination contains at least one carbonate and / or silicate filler.

6. Composition according to one of the preceding claims, characterized in that the filler combination contains at least one hard filler with a Mohs hardness > 5, preferably > 6, and at least one soft filler with a Mohs hardness < 5, preferably < 4.

7. Composition according to one of the preceding claims, characterized in that 3-41 wt.%, preferably 3-30 wt.%, further preferably 4-25 wt.% fillers are contained, based on the total weight of the starting materials.

8. Composition according to one of the preceding claims, characterized in that it contains 10-50 wt.%, preferably 15-40 wt.%, further preferably 20-35 wt.% of polymer binder based on the total weight of the starting materials.

9. Composition according to one of the preceding claims, characterized in that the at least one polymer binder is a polymer binder based on vinyl acetate / ethylene copolymers, copolymers based on vinyl aromatics, in particular styrene, and acrylates and / or homo- or copolymers based on pure acrylates, in particular based on styrene-acrylate copolymers, and / or pure acrylates comprising homo- or copolymers of acrylates and / or methacrylates, optionally with acrylic and / or methacrylic acid as comonomer building block.

10. Composition according to one of the preceding claims, characterized in that the at least one polymer binder is a polymer dispersion having a solids content of 30-65 wt.%, preferably 40-60 wt.%, further preferably 40-55 wt.%, based on the total weight of the polymer dispersion.

11. Composition according to one of the preceding claims, characterized in that additives are included, for example rheological additives, thickeners, pot and film preservatives, film binding aids, biocides, defoamers and / or fibers.

12. Composition according to one of the preceding claims, characterized in that 10-50 wt.% polymer binder (solids content) 1-8 wt.% inorganic fillers with an oil absorption > 100 2-40 wt.% carbonate and / or silicate fillers with a Oil number between 30 and 100, 0-20 wt% additional fillers 1-25 wt.% white and / or color pigments 0.01-5.0 wt.% other additives 10-50 wt.% water, based on the total weight of the starting materials.

13. Coating, in particular paint coating, made from a composition according to one of the preceding claims, wherein the coating has a wet abrasion resistance of class 1 and / or a gloss level of < 10 GU, preferably < 8 GU, further preferably < 7 GU.

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