Organic solvent-based retroreflective compositions for industrial spray applications

Abstract

The present invention relates to an organic solvent-based retroreflective ink, paint or coating composition having a first Brookfield viscosity η1 at a shear rate of 0.5 rpm of between 0.2 and 8 Pa s, and a second Brookfield viscosity η2 at a shear rate of 20 rpm of between 80 and 450 mPa s, with the proviso that η2 is at least 2 times lower than η1, wherein the organic solvent-based retroreflective ink, paint or coating composition consists of: • 25-75 wt% of an organic solvent; • 1-85 wt% of spherical glass beads; • 0.15-1.2 wt% of a thickening agent; and • 0-30 wt% of one or more other ingredients; wherein the Brookfield viscosities η1 and η2 are measured at a temperature of 25°C in a 600 ml beaker with a diameter of 8.25 cm using a #2 spindle.

Description

Technical Field

[0001] This invention relates to an organic solvent-based retroreflective composition and its preparation method. The invention further relates to a method for coating a substrate with a retroreflective layer using the organic solvent-based retroreflective composition, and to a substrate coated with a retroreflective layer obtained by this method. Background Technology

[0002] Retroreflective paints, inks, and coatings are used in a variety of applications. For example, they improve the visibility of road signs, road numbering markings, textiles, and automobiles in dark conditions. Paints, inks, and coatings typically provide retroreflective properties by adding spherical glass beads with a specific refractive index. Retroreflection occurs through a series of reactions: incident light is refracted through the upper surface of the spherical glass bead, internally refracted from the lower surface, and then further refracted as the light leaves the upper surface and travels back in the direction from which the impact light originated.

[0003] WO2004 / 017104A2 discloses a retroreflective composition comprising retroreflective microspheres, an adhesive system, and a thixotropic blend comprising at least two thixotropic tack reducers in amounts from about 2% to about 5% by weight based on the retroreflective composition. The retroreflective composition is intended for use as paints, inks, and coatings and is applied to a substrate using an aerosol applicator with a propellant. Table 1 of WO2004 / 017104A2 discloses typical and preferred amounts of various components in the composition. Example 1 of WO2004 / 017104A2 discloses a composition in which the solvent is an undefined aliphatic or aromatic naphtha, the solid resin particles are of an undefined acrylic type, the first thixotropic adhesive is of an undefined polyurea type, and the second thixotropic adhesive is an undefined calcium sulfonate complex. The composition of Example 1, measured at 25°C using a Brookfield #3 spindle, had an accompanying viscosity between 9000 and 30000 cps at 0.5 rpm and between 600 and 1900 cps at 20 rpm.

[0004] WO00 / 42113A1 relates to a reflective ink containing microbeads in a liquid carrier medium. The ink is intended for use in screen printing on textiles. WO00 / 42113A1 discloses that the viscosity of the screen printing ink, measured at room temperature using a Brookfield viscometer with a #5 spindle rotating at 10 rpm, is between 10 and 30 Pa·s. The inks disclosed in Tables 1-4 and 6 contain water, a thickener, and glass beads. Viscosities measured at room temperature using a Brookfield viscometer with a #5 spindle rotating at 10 rpm are between 12.3 and 32 Pa·s. Screen printing is a printing technique in which a paste-like ink is transferred onto a substrate using a screen, except through areas where the ink does not readily penetrate the stencil. A blade or squeegee moves across the screen to fill the open screen apertures with ink, and then a reverse stroke causes the screen to briefly contact the substrate along the contact line. This causes the ink to wet the substrate and be removed from the screen apertures as the screen springs back after the blade has passed through. As is generally known to printing technicians, screen printing inks and inks used for professional or industrial (high-speed) spraying have fundamentally different rheological properties because the techniques used to apply them to the substrates are different. Screen printing inks are not suitable for professional or industrial (high-speed) spraying.

[0005] Developing retroreflection compositions that exhibit good stability, sprayability, and produce good printing or coating quality is challenging because the rheology modifiers required to maintain a uniform distribution of retroreflection particles (such as spherical glass beads, which typically have a density substantially higher than that of the fluid carrier) within the fluid carrier often adversely affect the rheological properties during spraying.

[0006] The reflective ink, coating, or paint needs to be sufficiently stable, and preferably can be applied to a variety of substrates using professional or industrial (high-speed) spraying, producing a reflective layer or coating with improved quality.

[0007] Therefore, an object of the present invention is to provide a retroreflective composition that can be applied professionally or industrially as a paint, ink or coating to a variety of substrates, wherein the retroreflective composition can be applied to the substrate by spraying, such as professional or industrial (high-speed) spraying, and wherein the retroreflective composition has sufficient stability or shelf life.

[0008] Another object of the present invention is to provide a reflective composition that can be applied as a paint, ink or coating by spraying, such as professional or industrial (high-speed) spraying, onto a variety of substrates, thereby producing improved printing or coating quality such as good or improved layer uniformity or smoothness. Summary of the Invention

[0009] The inventors unexpectedly determined that one or more of the objectives can be achieved by using one or more organic solvent-based retroreflection compositions that exhibit shear-dilution behavior, have lower viscosity at increased shear rates and reduced thickener concentrations compared to prior art compositions.

[0010] Therefore, in a first aspect, the present invention provides an organic solvent-based retroreflective ink, paint, or coating composition having a first Brookfield viscosity η1 at a shear rate of 0.5 rpm between 0.2 and 8 Pa·s, and a second Brookfield viscosity η2 at a shear rate of 20 rpm between 80 and 450 mPa·s, provided that η2 is at least twice as low as η1, wherein the organic solvent-based retroreflective ink, paint, or coating composition comprises, based on the total weight of the composition, the following:

[0011] • 25-75% by weight of organic solvent;

[0012] • 1-85% by weight of spherical glass beads with a median particle size D50 between 1 and 150 μm as measured by laser diffraction and a refractive index between 1.5 and 2.8 as measured at a wavelength λ of 589 nm;

[0013] • 0.15-1.2% by weight of thickener; and

[0014] • 0-30% by weight of one or more other ingredients;

[0015] Brookfield viscosities η1 and η2 were measured at 25°C using a #2 spindle in a 600ml beaker with a diameter of 8.25cm.

[0016] The inventors have determined that this organic solvent-based retroreflective composition can be applied to various substrates, for example, using professional or industrial (high-speed) spraying, to produce a retroreflective coating layer with excellent printing or coating quality.

[0017] By reducing the amount of thickener and decreasing the viscosity at a shear rate of 20 rpm, a retroreflective layer with improved uniformity and smoothness is obtained, more specifically, a layer with less "orange peel" texture. The reduction in the amount of thickener not only decreases the viscosity at increased shear rates (representing spraying conditions) but also at low shear rates (related to stability). The inventors have unexpectedly discovered that the reduced amount of thickener required to obtain the retroreflective layer with improved uniformity and smoothness remains suitable for providing organic solvent-based retroreflective ink, paint, or coating compositions with sufficient stability or shelf life.

[0018] In a second aspect, a method is provided for preparing an organic solvent-based retroreflective ink, paint, or coating composition as defined herein, the method comprising the steps of:

[0019] (i) Adding an organic solvent, spherical glass beads as defined above, a thickener as defined above, and one or more other ingredients as defined above, as appropriate, to the container; and

[0020] (ii) Preferably, the mixture obtained in step (i) is stirred or homogenized at a temperature between 15°C and 70°C for a period of time between 5 minutes and 60 minutes.

[0021] In a third aspect, the present invention provides a method for coating a substrate with a retroreflective layer, the method comprising the following steps:

[0022] a) Provide a substrate;

[0023] b) Apply the primer layer to the substrate from step (a) as needed;

[0024] c) Depending on the circumstances, but not preferably, apply the colored base layer to the substrate of step (a) or the primer layer of step (b);

[0025] d) Spraying an organic solvent-based retro-printing ink, paint, or coating composition as defined above onto the substrate of step (a) or the layer of step (b) or (c);

[0026] e) Drying and / or curing the substrate coated with the retroreflection layer obtained in step (d); and

[0027] f) Depending on the situation, coat the dried substrate coated with the retroreflection layer obtained in step (e) with one or more other transparent coating layers.

[0028] In a fourth aspect, the present invention relates to a substrate coated with a retroreflective layer, which is obtained or can be obtained by a method for coating a substrate as defined herein.

[0029] definition

[0030] As used herein, the term “orange peel wrinkle” refers to a speckled printing defect characterized by a grainy image reminiscent of orange peel texture, caused by ink failing to flow to a smooth film layer.

[0031] In the context of the organic solvent-based reflective ink, paint, or coating compositions of the present invention, the term "shear dilution behavior" refers to the reduction in viscosity when a composition initially in a static state is subjected to a shear rate. Attached Figure Description

[0032] Figures 1a to 1h The smoothness / orange peel texture of the retroreflective coatings prepared using the compositions according to the present invention and comparative compositions is depicted. Detailed Implementation

[0033] In a first aspect, the present invention relates to an organic solvent-based retroreflective ink, paint, or coating composition having a first Brookfield viscosity η1 at a shear rate of 0.5 rpm between 0.2 and 8 Pa·s, and a second Brookfield viscosity η2 at a shear rate of 20 rpm between 80 and 450 mPa·s, provided that η2 is at least twice as low as η1, wherein the organic solvent-based retroreflective ink, paint, or coating composition comprises, based on the total weight of the composition, the following:

[0034] • 25-75% by weight of organic solvent;

[0035] • 1-85% by weight of spherical glass beads with a median particle size D50 between 1 and 150 μm as measured by laser diffraction and a refractive index between 1.5 and 2.8 as measured at a wavelength λ of 589 nm;

[0036] • 0.15-1.2% by weight of thickener; and

[0037] • 0-30% by weight of one or more other ingredients;

[0038] Brookfield viscosities η1 and η2 were measured at 25°C using a #2 spindle in a 600ml beaker with a diameter of 8.25cm.

[0039] In a preferred embodiment, the first aspect relates to an organic solvent-based retroreflective ink, paint, or coating composition having a first Brookfield viscosity η1 at a shear rate of 0.5 rpm between 0.2 and 8 Pa·s and a second Brookfield viscosity η2 at a shear rate of 20 rpm between 80 and 450 mPa·s, provided that η2 is at least twice as low as η1, wherein the organic solvent-based retroreflective ink, paint, or coating composition comprises, based on the total weight of the composition, the following:

[0040] • 25-68% by weight of organic solvents;

[0041] • 20-70% by weight of spherical glass beads with a median particle size D50 between 5 and 150 μm as measured by laser diffraction and a refractive index between 1.5 and 2.8 as measured at a wavelength λ of 589 nm.

[0042] • 0.15-1.2% by weight of thickener; and

[0043] • 0-30% by weight of one or more other ingredients;

[0044] Brookfield viscosities η1 and η2 were measured at 25°C using a #2 spindle in a 600ml beaker with a diameter of 8.25cm.

[0045] stability

[0046] In a preferred embodiment, the organic solvent-based reflective ink, paint, or coating composition remains stable for at least 12 hours, more preferably at least 1 day, even more preferably at least 2 days, at least 5 days, at least 10 days, at least 1 month, at least 2 months, at least 6 months, at least 1 year, or at least 2 years, wherein the composition is considered stable if no precipitation or separation can be observed during visual and tactile inspection. In a preferred embodiment, the organic solvent-based reflective ink, paint, or coating composition remains spray-stable for at least 24 hours. The composition is considered spray-stable if it is sprayed without premixing.

[0047] organic solvents

[0048] As used herein, the term "organic solvent" means an organic solvent or a mixture of organic solvents containing less than 3% by weight of water, preferably less than 2% by weight of water, more preferably less than 1% by weight of water, even more preferably less than 0.5% by weight of water, and most preferably free of water.

[0049] Preferred organic solvents are selected from the group consisting of: aliphatic and aromatic solvents, ketones, esters, ethylene glycol ethers, alcohols, halogenated hydrocarbons and combinations thereof. Most preferred organic solvents are selected from the group consisting of: xylene (a mixture of isomers), toluene, ethylbenzene, naphtha, 1,2,4-trimethylbenzene, trimethylbenzene, n-propylbenzene, isoamyl acetate, n-butyl acetate, (2-methoxymethylethoxy)propanol, 2-butoxyethyl acetate, 2-methylbutyl acetate, isobutanol, 1-butanol, 1-ethoxypropane-2-ol, 2,6-dimethyl-4-heptanone, 2-methoxy-1-methylethyl acetate, 4,6-dimethyl-heptane-2-one, 4-methyl-2-pentanone, 1-methoxy-2-propanol, 1-methoxy-2-propyl acetate, 2-(2-butoxyethoxy)ethanol, 2-butoxyethanol, 5-methylhexane-2-one, ethyl acetate and combinations thereof.

[0050] In a preferred embodiment, the amount of organic solvent is 25-68% by weight, based on the total weight of the organic solvent-based reflective ink, coating, or paint composition.

[0051] In a preferred embodiment, the amount of organic solvent is 27-65% by weight, more preferably 30-60% by weight, and even more preferably 35-58% by weight, based on the total weight of the organic solvent-based reflective ink, coating, or paint composition.

[0052] In the embodiments, the amount of organic solvent is 25-66% by weight, 25-62% by weight, 25-60% by weight, 25-58% by weight, or 25-56% by weight, based on the total weight of the organic solvent-based reflective ink, coating, or paint composition.

[0053] In other embodiments, the amount of organic solvent is 28-68% by weight, 30-68% by weight, 32-68% by weight, 34-68% by weight, 36-68% by weight, 38-68% by weight, or 40-68% by weight, based on the total weight of the organic solvent-based reflective ink, coating, or paint composition.

[0054] In other embodiments, the amount of organic solvent is 28-75% by weight, 30-75% by weight, 32-75% by weight, 34-75% by weight, 36-75% by weight, 38-75% by weight, or 40-75% by weight, based on the total weight of the organic solvent-based reflective ink, coating, or paint composition.

[0055] Spherical glass beads

[0056] As defined above, the refractive index of a spherical glass bead measured at a wavelength λ of 589 nm is between 1.5 and 2.8.

[0057] In a preferred embodiment, the refractive index of the spherical glass bead measured at a wavelength λ of 589 nm is:

[0058] (a) Between 2.0 and 2.8, preferably between 2.1 and 2.4; or

[0059] (b) Between 1.7 and 2.1, preferably between 1.8 and 2.0.

[0060] In a preferred embodiment, as used herein, the term "glass" in "spherical glass beads" refers to a non-crystalline, amorphous solid and transparent material made of oxides. In other embodiments, the term "glass" in "spherical glass beads" refers to a solid and transparent material made of oxides and containing some microcrystalline properties. The refractive index of spherical glass beads is closely related to the density of the glass, although the relationship is not linear. Due to the properties of glass, density is approximately an additive function of its composition. Spherical glass beads with a refractive index between 1.5 and 2.8 typically have densities between 2.5 and 4.5 g / cm³. 3 The changes between them.

[0061] Oxides that can be used in glass include oxides of silicon, boron, aluminum, sodium, barium, vanadium, titanium, lanthanum, strontium, zirconium, potassium, magnesium, iron, calcium, zinc, lithium, barium, and lead. Spherical glass beads can contain, for example, different combinations of the following: silicon dioxide (SiO2), boron oxide (B2O3), phosphorus pentoxide (P2O5), vanadium pentoxide (V2O5), arsenic trioxide (As2O3), germanium oxide (GeO2), calcium oxide (CaO), sodium oxide (Na2O), magnesium oxide (MgO), zinc oxide (ZnO), aluminum oxide (Al2O3), potassium oxide (K2O), ferric oxide (Fe2O3), lead oxide (PbO), barium oxide (BaO), barium titanate (BaTiO3), titanium dioxide (TiO2), lithium oxide (Li2O), strontium oxide (SrO), lanthanum oxide (La2O3), and zirconium dioxide (ZrO2). Silicon dioxide and boron oxide typically have the lowest densities. Glasses containing a large percentage of these oxides typically produce glass beads with a low refractive index. The refractive index is increased by adding oxides with higher molecular weights. Preferably, the spherical glass beads do not contain PbO.

[0062] Glass beads with a refractive index in the range of 1.5-2.51 and composed of oxides are disclosed in WO2014 / 109564A1, which is incorporated herein by reference in its entirety. Transparent glass beads without PbO and with a refractive index greater than 2.15 are disclosed in US4,082,427, which is incorporated herein by reference in its entirety.

[0063] Spherical glass beads can be colored spherical glass beads, as long as they remain transparent. This invention covers colored spherical glass beads made of colored transparent glass and spherical glass beads provided with a concentric transparent colored coating. The color can be a natural color caused by a composition of oxides or can be selected by intentionally adding colorimetric components. Colored glass beads with high refractive index and high transparency are disclosed in WO2014 / 109564A1.

[0064] Therefore, in one embodiment, at least a portion of the spherical glass beads are glass beads made of colored transparent glass and / or at least a portion of the spherical glass beads are provided with a concentric transparent colored coating.

[0065] Spherical glass beads have a median particle size D50, as measured using laser diffraction. Therefore, based on volume distribution, the median particle size D50 is the volume median value. The median particle size D50 is the diameter below which half of the spherical glass bead population is located. This volume median particle size is commonly referred to in this technique as Dv50 or D... v0.5 .

[0066] In a preferred embodiment, the median particle size D50 of the spherical glass beads, as measured by laser diffraction, is between 5 and 150 μm.

[0067] In one embodiment, the median particle size D50 of the spherical glass beads, as measured by laser diffraction, is between 25 and 100 μm, preferably between 30 and 75 μm, and more preferably between 35 and 50 μm.

[0068] In a preferred embodiment, the spherical glass beads have a median particle size D50, measured using laser diffraction, between 5 and 100 μm, such as between 5 and 75 μm, between 5 and 50 μm, between 5 and 45 μm, between 5 and 40 μm, or between 5 and 35 μm.

[0069] In a preferred embodiment, the median particle size D50 of the spherical glass beads, as measured by laser diffraction, is between 1 and 100 μm, such as between 1 and 75 μm, between 1 and 50 μm, between 1 and 45 μm, between 1 and 40 μm, between 1 and 35 μm, between 1 and 30 μm, between 1 and 25 μm, between 1 and 20 μm, between 1 and 15 μm, or between 1 and 10 μm.

[0070] In yet another embodiment, the median particle size D50 of the spherical glass beads, as measured by laser diffraction, is between 25 and 150 μm, such as between 50 and 150 μm, 75 and 150 μm, 100 and 150 μm, 110 and 150 μm, or 115 and 150 μm.

[0071] Diameters D10 and D90 are typically referred to as Dv10 or D in this technology, respectively. v0.1 and Dv90 or D v0.9 The D10 diameter is the diameter that is lower than that of 10% of the spherical glass beads. Similarly, the D90 diameter is the diameter that is lower than that of 90% of the spherical glass beads.

[0072] The particle size distribution of spherical glass beads, as measured by laser diffraction, is defined by the following:

[0073]

[0074] In another embodiment, the spherical glass beads have a median particle size D50 between 15 and 100 μm, as measured by laser diffraction, and a span between 0 and 1.9, such as between 0 and 1.5, 0 and 1, 0 and 0.5, 0 and 0.2, or 0 and 0.1.

[0075] In yet another embodiment, the spherical glass beads have a median particle size D50 between 30 and 75 μm as measured by laser diffraction, and a span between 0 and 1.9, such as between 0 and 1.5, 0 and 1, 0 and 0.5, 0 and 0.2, or 0 and 0.1.

[0076] In another preferred embodiment, the spherical glass beads have a median particle size D50 between 15 and 50 μm as measured by laser diffraction, and a span between 0 and 1.9, such as between 0 and 1.5, 0 and 1, 0 and 0.5, 0 and 0.2, or 0 and 0.1.

[0077] In yet another preferred embodiment, the spherical glass beads have a median particle size D50 of 1 to 35 μm as measured by laser diffraction, and a span between 0 and 1.9, such as between 0 and 1.5, 0 and 1, 0 and 0.5, 0 and 0.2, or 0 and 0.1.

[0078] In yet another preferred embodiment, the spherical glass beads have a median particle size D50 of 5 to 35 μm as measured by laser diffraction, and a span between 0 and 1.9, such as between 0 and 1.5, 0 and 1, 0 and 0.5, 0 and 0.2, or 0 and 0.1.

[0079] In yet another preferred embodiment, the spherical glass beads have a median particle size D50 of 10 to 25 μm as measured by laser diffraction, and a span between 0 and 1.9, such as between 0 and 1.5, 0 and 1, 0 and 0.5, 0 and 0.2, or 0 and 0.1.

[0080] In yet another preferred embodiment, the spherical glass beads have a median particle size D50 of 1 to 25 μm as measured by laser diffraction, and a span between 0 and 1.9, such as between 0 and 1.5, 0 and 1, 0 and 0.5, 0 and 0.2, or 0 and 0.1.

[0081] In yet another preferred embodiment, the spherical glass beads have a median particle size D50 of 1 to 15 μm as measured by laser diffraction, and a span between 0 and 1.9, such as between 0 and 1.5, 0 and 1, 0 and 0.5, 0 and 0.2, or 0 and 0.1.

[0082] In yet another preferred embodiment, the spherical glass beads have a median particle size D50 of 1 to 10 μm as measured by laser diffraction, and a span between 0 and 1.9, such as between 0 and 1.5, 0 and 1, 0 and 0.5, 0 and 0.2, or 0 and 0.1.

[0083] As understood by those skilled in the art, a span of 0 corresponds to a monodisperse spherical glass bead.

[0084] In a preferred embodiment, at least a portion of the spherical glass beads are coated with a light-reflective coating, preferably a hemispherical aluminum coating (HAC). In another embodiment, at least a portion of the spherical glass beads are coated with a fluorine chemical coating.

[0085] In a preferred embodiment, the amount of spherical glass beads is 20-70% by weight, based on the total weight of the organic solvent-based reflective ink, coating, or paint composition.

[0086] In a preferred embodiment, the amount of spherical glass beads is 23-68% by weight, more preferably 25-65% by weight, and even more preferably 28-63% by weight, based on the total weight of the organic solvent-based reflective ink, coating, or paint composition.

[0087] In the embodiments, the amount of spherical glass beads is 20-65% by weight, 20-63% by weight, 20-60% by weight, 20-57% by weight, 20-54% by weight, 20-52% by weight, or 20-50% by weight, based on the total weight of the organic solvent-based reflective ink, coating, or paint composition.

[0088] In this embodiment, the amount of spherical glass beads is 1-80% by weight, 1-78% by weight, 1-76% by weight, 1-74% by weight, 1-72% by weight, 1-70% by weight, or 1-68% by weight, based on the total weight of the organic solvent-based reflective ink, coating, or paint composition.

[0089] In other embodiments, the amount of spherical glass beads is 22-70% by weight, 24-70% by weight, 26-70% by weight, 27-70% by weight, 28-70% by weight, 29-70% by weight, or 30-70% by weight, based on the total weight of the organic solvent-based reflective ink, coating, or paint composition.

[0090] In yet another embodiment, the amount of spherical glass beads is 2-85% by weight, 5-85% by weight, 8-85% by weight, 10-85% by weight, 12-85% by weight, 14-85% by weight, or 16-85% by weight, based on the total weight of the organic solvent-based reflective ink, coating, or paint composition.

[0091] The specific application of an organic solvent-based retroreflective ink, coating, or paint composition determines the optimal refractive index of the spherical glass beads. If the composition is to be applied in a dry environment or onto a substrate that displays retroreflection under dry conditions, and the applied layer of the retroreflective spherical glass beads is not coated with another layer, the refractive index of the spherical glass beads measured at a wavelength λ of 589 nm can be between 1.8 and 2.8.

[0092] In one embodiment, the organic solvent-based retroreflective ink, coating, or paint composition as defined herein comprises spherical glass beads with a refractive index between 1.8 and 2.0 as measured at a wavelength λ of 589 nm.

[0093] On the other hand, if the composition is intended for application in a humid environment or on a substrate exhibiting retroreflection under humid conditions, or if the applied layer of the retroreflective spherical glass beads is coated with one or more other transparent layers, the refractive index of the spherical glass beads, measured at a wavelength λ of 589 nm, is preferably between 2.0 and 2.8, more preferably between 2.2 and 2.4. Compositions exhibiting retroreflection under both dry and humid conditions, wherein the applied layer of the retroreflective spherical glass beads is coated with one or more other transparent layers or is not coated, may contain different types of glass beads with different refractive indices and, where appropriate, different sizes. In one embodiment, an organic solvent-based retroreflective ink, coating, or paint composition as defined herein includes spherical glass beads with a refractive index measured at a wavelength λ of 589 nm between 2.0 and 2.8, preferably between 2.2 and 2.4.

[0094] In another embodiment, the organic solvent-based retroreflective ink, coating, or paint composition as defined herein comprises at least two types of spherical glass beads, wherein at least one type of spherical glass beads has a refractive index between 1.8 and less than 2.0 when measured at a wavelength λ of 589 nm, and at least one other type of spherical glass beads has a refractive index between 2.0 and 2.8 when measured at a wavelength λ of 589 nm.

[0095] Thickener

[0096] Organic solvent-based retroreflective ink, coating, or paint compositions contain thickeners. It is not intended to be bound by any theory, but it is believed that thickeners limit or reduce the settling and / or precipitation of spherical glass beads and, where appropriate, other particulate matter in organic solvent-based retroreflective ink, coating, or paint compositions, thereby allowing the composition to be easily resuspended. Furthermore, it is not intended to be bound by any theory, but it is believed that thickeners provide organic solvent-based retroreflective ink, coating, or paint compositions with shear-dilution behavior.

[0097] In a preferred embodiment, the thickener comprises a mixture of different thickeners.

[0098] Preferred examples of thickeners suitable for use in organic solvent-based reflective inks, coatings, or paint compositions are selected from the group consisting of: (modified) halogenated castor oil, clay, modified clay, calcium sulfonate complexes, organophilic layered silicates, silica gel, synthetic amorphous silica, acrylic gelling agents, modified cellulose materials, polyurea dispersions, urea-modified polyamide solutions, polyurethane dispersions, and combinations thereof.

[0099] Examples of modified clay include LT and 38 (Elementis Global). Examples of silicone include... N20 (Wacker Chemical Corporation) and (Evonik). An example of an organophilic layered silicate is Claytone 40 (Byk). An example of modified halogenated castor oil is... RM1900 (BASF). An example of halogenated castor oil is... RM 1920 (BASF). A solution of urea-modified nonpolar polyamide in isobutanol / monophenyl glycol is Rheobyk-431 (Byk). A solution of moderately polar urea-modified polyamide in isobutanol / solvent naphtha is Rheobyk-430 (Byk). An example of synthesizing amorphous silica is... (Huber).

[0100] In a preferred embodiment, two thickeners are used in the organic solvent-based reflective ink, coating, or paint composition, more preferably:

[0101] • Organic-friendly layered silicates and modified halogenated castor oil; or

[0102] • Calcium sulfonate complexes and polyurea dispersions.

[0103] In a preferred embodiment, the amount of thickener is 0.20-1.18% by weight, more preferably 0.25-1.15% by weight, and even more preferably 0.30-1.10% by weight, based on the total weight of the organic solvent-based reflective ink, coating, or paint composition.

[0104] In this embodiment, the amount of thickener is 0.15-1.18% by weight, 0.15-1.15% by weight, or 0.15-1.10% by weight, based on the total weight of the organic solvent-based reflective ink, coating, or paint composition.

[0105] In other embodiments, the amount of thickener is 0.20-1.20 wt%, 0.30-1.20 wt%, 0.40-1.20 wt%, 0.45-1.20 wt%, or 0.50-1.20 wt%, based on the total weight of the organic solvent-based reflective ink, coating, or paint composition.

[0106] The amount of organic solvent in an organic solvent-based reflective ink, coating, or paint composition is specified independently. If the thickener is applied, for example, as a dispersion in a solvent, the amount of thickener as defined above relates to the dry weight of the thickener.

[0107] Other ingredients

[0108] As described above, the organic solvent-based reflective ink, paint, or coating composition contains 0-30% by weight of one or more other ingredients. As those skilled in the art will understand, "other" ingredients differ from the other ingredients defined in the organic solvent-based reflective ink, paint, or coating composition. In other words, the other ingredients do not include spherical glass beads, thickeners, and organic solvents.

[0109] In a preferred embodiment, one or more other components are selected from the group consisting of: foam control agents, luminescent agents, UV absorbers, adhesives and resins, preservatives, dyes, pigments and curing initiators.

[0110] Suitable binders and resins for use in organic solvent-based compositions are generally known to those skilled in the art. The binder or resin may be radiation-curable. If the binder or resin is radiation-curable, other components may include a curing initiator, such as a photoinitiator or a thermal initiator.

[0111] In one embodiment, the organic solvent-based reflective ink, paint, or coating composition comprises, as part of one or more other components, a synthetic pigment flake having an average diameter between 5 and 50 μm, a thickness of less than 1 μm, and an aspect ratio (flake diameter / thickness) of at least 10, wherein the synthetic pigment flake is selected from (A), (B), (C), or a combination thereof:

[0112] (A) A metal sheet or synthetic mica sheet, which, as appropriate, is coated with at least one layer of one or more components selected from the group consisting of metal oxides, metals, metal sulfides, low-valent titanium oxides, titanium oxynitrides, FeO(OH), SiO2, B2O3, GeO2, MgF2, metal alloys, and rare earth compounds, and is coated with an outer layer containing one or more colorants and binders.

[0113] (B) A sheet comprising Al2O3, SiO2, glass, ceramic, graphite and mica flakes, wherein, as appropriate, it is coated with at least one layer of one or more components selected from the group consisting of metal oxides, metals, metal sulfides, low-valent titanium oxides, titanium oxynitride, FeO(OH), SiO2, B2O3, GeO2, metal alloys and rare earth compounds, and wherein, as appropriate, it is coated with an outer layer comprising one or more colorants and binders.

[0114] (C) A sheet containing Al2O3 flakes doped with one or more components selected from the group consisting of TiO2, ZrO2, SiO2, SnO2, In2O3, ZnO and iron oxide, which may be coated with at least one layer of one or more components selected from the group consisting of metal oxides, metals, metal sulfides, low-valent titanium oxides, titanium oxynitride, FeO(OH), SiO2, B2O3, GeO2, metal alloys and rare earth compounds, and which may be coated with an outer layer containing one or more colorants and binders.

[0115] In the context of synthetic pigment flakes, the term "average diameter" refers to the median particle size D50.

[0116] As understood by those skilled in the art, the term "synthetic" in "synthetic pigment flakes" means that the pigment flakes are not naturally occurring pigment flakes, but rather that they are chemically manufactured pigment flakes or naturally occurring pigment flakes that have undergone chemical / physical treatment. One advantage of using synthetic pigment flakes is that they can produce very smooth surfaces, thereby increasing their reflective properties.

[0117] As used herein, the term "flake" or "particle" refers to a pigment shape having a large surface area and a small thickness. Typically, a flake or particle is characterized by its "aspect ratio," which is defined as the maximum dimension (i.e., the maximum diameter of the surface) divided by the minimum dimension (i.e., the thickness). As used herein, the aspect ratio of synthetic pigment flakes is at least 10, preferably at least 15, and more preferably at least 20.

[0118] In a preferred embodiment, the average diameter of the composite sheet is 6-45 μm, more preferably 7-35 μm, even more preferably 8-25 μm, still more preferably 9-20 μm, and most preferably 10-16 μm.

[0119] In a preferred embodiment, the thickness of the composite sheet is between 10 nm and 800 nm, more preferably between 15 nm and 600 nm. In another preferred embodiment, the thickness of the composite sheet is between 10 and 200 nm, more preferably between 10 and 150 nm, even more preferably between 10 and 100 nm, and still more preferably between 10 and 50 nm.

[0120] In the embodiments, based on the total weight of the organic solvent-based reflective ink, paint, or coating composition, the amount of one or more other components is 0-25% by weight, 0-20% by weight, 0-15% by weight, 0-12% by weight, 0-10% by weight, 0-8% by weight, 0-6% by weight, or 0-5% by weight.

[0121] In other embodiments, the amount of one or more other components is 0.1-23% by weight, 0.5-17% by weight, or 1-15% by weight, based on the total weight of the organic solvent-based reflective ink, paint, or coating composition.

[0122] The amount of organic solvent in an organic solvent-based reflective ink, paint, or coating composition is specified independently. If one or more other components are applied in the form of, for example, a solution, suspension, or dispersion in a solvent, the amount of the one or more other components as defined above is relative to the dry weight of the one or more other components, i.e., the weight excluding the solvent.

[0123] rheological behavior

[0124] Organic solvent-based reflective ink, paint, or coating compositions exhibit shear-dilution behavior. This means that the composition has a reduced viscosity when its static / steady state is disturbed by subjecting it to a certain increased shear rate.

[0125] As defined above, the first Brookfield viscosity η1 of an organic solvent-based retroreflective ink, paint, or coating composition, as defined herein, is between 0.2 and 8 Pa·s at a shear rate of 0.5 rpm, and the second Brookfield viscosity η2 is between 80 and 450 mPa·s at a shear rate of 20 rpm, provided that η2 is at least twice as low as η1, as measured using a #2 spindle in a 600 ml beaker with a diameter of 8.25 cm at 25°C.

[0126] In one preferred embodiment, η1 is between 0.25 and 5 Pa·s and η2 is between 100 and 425 mPa·s, provided that η2 is at least twice as low as η1. In another preferred embodiment, η1 is between 0.26 and 2.5 Pa·s and η2 is between 110 and 400 mPa·s, provided that η2 is at least twice as low as η1. In yet another preferred embodiment, η1 is between 0.27 and 2 Pa·s and η2 is between 120 and 350 mPa·s, provided that η2 is at least twice as low as η1.

[0127] The first viscosity η1 of the organic solvent-based retroreflective ink, paint, or coating composition, determined at a shear rate of 0.5 rpm, is sufficient to retain spherical glass beads and other particulate materials, selected as appropriate, in the suspension for a sufficiently long period. For (industrial) spraying conditions, a shear rate of 20 rpm is typical, under which the organic solvent-based retroreflective ink, paint, or coating composition can be applied to the substrate. The second viscosity η2 is sufficiently low to provide an easily sprayable organic solvent-based retroreflective ink, paint, or coating composition.

[0128] In a preferred embodiment, the third Brookfield viscosity η3 of the organic solvent-based retroreflective ink, paint, or coating composition at a shear rate of 10 rpm is less than 1.5 Pa·s, more preferably less than 1.3 Pa·s, and even more preferably less than 1.1 Pa·s, such as less than 1.0 Pa·s, less than 0.8 Pa·s, or less than 0.6 Pa·s, as measured using a #5 spindle in a 600 ml beaker with a diameter of 8.25 cm at 25°C.

[0129] In another preferred embodiment, the fourth Brookfield viscosity η4 of the organic solvent-based retroreflective ink, paint, or coating composition, as defined herein, is between 0.25 and 5 Pa·s at a shear rate of 0.5 rpm, and the fifth Brookfield viscosity η5 is between 80 and 450 mPa·s at a shear rate of 20 rpm, provided that η5 is at least twice as low as η4, as measured using a #3 spindle in a 600 ml beaker with a diameter of 8.25 cm at 25°C.

[0130] In yet another preferred embodiment, the fourth Brookfield viscosity η4 of the organic solvent-based retroreflective ink, paint, or coating composition, as defined herein, is between 0.30 and 3 Pa·s at a shear rate of 0.5 rpm, and the fifth Brookfield viscosity η5 is between 100 and 425 mPa·s at a shear rate of 20 rpm, provided that η5 is at least twice as low as η4, as measured using a #3 spindle in a 600 ml beaker with a diameter of 8.25 cm at 25°C.

[0131] In yet another preferred embodiment, the fourth Brookfield viscosity η4 of the organic solvent-based retroreflective ink, paint, or coating composition, as defined herein, is between 0.35 and 2.5 Pa·s at a shear rate of 0.5 rpm, and the fifth Brookfield viscosity η5 is between 110 and 400 mPa·s at a shear rate of 20 rpm, provided that η5 is at least twice as low as η4, as measured using a #3 spindle in a 600 ml beaker with a diameter of 8.25 cm at 25°C.

[0132] Method for preparing organic solvent-based retro-ink, paint, or coating compositions

[0133] Generally, the components of an organic solvent-based reflective ink, coating, or paint composition can be added in any order. However, it is preferred to add the thickener at the end of the process, at least after the spherical glass beads are added to the organic solvent, because it is more difficult to uniformly distribute the components in the thickened composition.

[0134] In a preferred embodiment, the thickener is added after the organic solvent is mixed with the spherical glass beads. In another preferred embodiment, the thickener is added after the organic solvent, spherical glass beads, and any other ingredients are mixed. Stirring or homogenization is preferably performed at a low shear rate to avoid the inclusion of air bubbles in the organic solvent-based reflective ink, coating, or paint composition.

[0135] In a second aspect, a method is provided for preparing an organic solvent-based retroreflective ink, coating, or paint composition as defined herein, the method comprising the steps of:

[0136] (i) Adding an organic solvent, spherical glass beads as defined above, a thickener as defined above, and one or more other ingredients as defined above, as appropriate, to the container; and

[0137] (ii) Preferably, the mixture obtained in step (i) is stirred or homogenized at a temperature between 15°C and 70°C for a period of time between 5 minutes and 60 minutes.

[0138] However, the addition of different components is also carried out at different stages of this method. Therefore, in one embodiment, a method is provided for preparing an organic solvent-based reflective ink, coating, or paint composition as defined herein, the method comprising the following steps:

[0139] (i) Add an organic solvent, spherical glass beads as defined above, at least a portion of a thickener as defined above, and, as appropriate, a portion of one or more other ingredients as defined above to the container;

[0140] (ii) The mixture obtained in step (i) is preferably stirred or homogenized at a temperature between 15°C and 70°C for a period of 5 to 60 minutes.

[0141] (iii) Adding at least a portion of one or more other ingredients as defined above to the composition obtained in step (ii) or (iii), and, where appropriate, adding a portion of a thickener as defined above and, where appropriate, an organic solvent; and

[0142] (iv) Preferably, the mixture obtained in step (iii) is stirred or homogenized at a temperature between 15°C and 70°C for a period of time between 5 minutes and 60 minutes.

[0143] In the implementation, the time between steps (i) and (ii) and between steps (iii) and (iv) can be several days, several months or longer.

[0144] Methods for preparing organic solvent-based retroreflective ink, coating, or paint compositions may also include producing an intermediate organic solvent-based retroreflective ink, coating, or paint composition having the composition and properties described above, followed by adding and mixing another component to obtain a final organic solvent-based retroreflective ink, coating, or paint composition, provided that the final organic solvent-based retroreflective ink, coating, or paint composition still has the composition and properties described above.

[0145] Therefore, in one embodiment, a method is provided for preparing an organic solvent-based reflective ink, coating, or paint composition as defined herein, the method comprising the following steps:

[0146] (i) Add an organic solvent, spherical glass beads as defined above, at least a portion of a thickener as defined above, and, as appropriate, a portion of one or more other ingredients as defined above to the container;

[0147] (ii) Preferably, the mixture obtained in step (i) is stirred or homogenized at a temperature between 15°C and 70°C for a period of time between 5 and 60 minutes to obtain an intermediate organic solvent-based retro-reflective ink, coating or paint composition having the composition and properties of an organic solvent-based retro-reflective ink, coating or paint composition as defined above.

[0148] (iii) Adding at least a portion of one or more other components as defined above to the intermediate organic solvent-based retroreflective ink, coating, or paint composition obtained in step (ii), and, where appropriate, adding a portion of a thickener as defined above and, where appropriate, an organic solvent; and

[0149] (iv) Preferably, the mixture obtained in step (iii) is stirred or homogenized at a temperature between 15°C and 70°C for a period of time between 5 minutes and 60 minutes to obtain an organic solvent-based reflective ink, coating or paint composition.

[0150] In the implementation, the time between steps (i) and (ii) and between steps (iii) and (iv) can be several days, several months or longer.

[0151] Method for coating substrates

[0152] In a third aspect, the present invention relates to a method for coating a substrate with a retroreflective layer, the method comprising the following steps:

[0153] a) Provide a substrate;

[0154] b) Apply the primer layer to the substrate from step (a) as needed;

[0155] c) Depending on the circumstances, but not preferably, apply the colored base layer to the substrate of step (a) or the primer layer of step (b);

[0156] d) Spraying an organic solvent-based retro-printing ink, coating, or paint composition as defined above onto the substrate of step (a) or the layer of step (b) or (c);

[0157] e) Drying and / or curing the substrate coated with the retroreflection layer obtained in step (d); and

[0158] f) Apply one or more additional transparent coating layers to the dried substrate coated with the retroreflective layer obtained in step (e), and then dry and / or cure.

[0159] Step (d) of spraying an organic solvent-based reflective ink, coating, or paint composition can consist of spraying a single layer in one step or spraying multiple layers on top of each other in subsequent spraying steps. Subsequent layers are preferably applied using a "wet-in-wet technique," meaning that the later layer is applied over the previous one, at least some to virtually all of the organic solvent evaporates from that layer, but is not (fully) cured. This means that even when subsequent layers are applied using a "wet-in-wet technique," an intermediate drying step is applied between the application of subsequent layers.

[0160] The intermediate drying of the layers is usually carried out at a temperature between 20°C and 30°C for about 2 to 15 minutes.

[0161] It is also possible to completely dry and / or cure the previous layer before applying the next layer. Complete drying and / or curing of a layer typically takes about 20 or 30 minutes at a temperature of about 60°C, or about 20°C in open air. Choosing appropriate drying conditions is within the skill of the technician.

[0162] In one embodiment, step (d) includes spraying more than one layer, such as 2, 3, 4 or 5 layers.

[0163] In one embodiment, step (d) includes n subsequent spraying steps to produce n layers, wherein layer x is at least partially applied to layer x-1, where x is an integer between 2 and n, and where n is an integer between 2 and 5.

[0164] In a preferred embodiment, the organic solvent-based reflective ink, coating, or paint composition is used in step (d) at a concentration of 100-800 g / m 2 The substrate amount is preferably 100-400 g / m². 2 The amount of substrate applied.

[0165] In one embodiment, step (b) is omitted. In a highly preferred embodiment, step (c) is omitted.

[0166] The geometry of the substrate to be coated is not limited in any sense, as long as it can be coated by spraying, that is, as long as droplets of the organic solvent-based reflector ink, coating, or paint composition can reach the surface of the substrate. In one embodiment, the substrate is planar. In other embodiments, the substrate is curved. In other embodiments, the substrate includes both planar and curved portions.

[0167] The inventors have determined that organic solvent-based retroreflective inks, coatings, or paint compositions can be applied to various substrates, for example, using professional or industrial (high-speed) spraying, to produce retroreflective coating layers with excellent printing or coating quality (such as uniformity and retroreflection at wide angles). These results can be obtained when the organic solvent-based retroreflective ink, coating, or paint composition is applied to the surface of a vertically positioned substrate, even when the substrate surface is sprayed from below.

[0168] If the retroreflective coating layer is provided with one or more other transparent coating layers (i.e., step (f) of the method for coating a substrate as defined herein) is performed, a retroreflective layer with high smoothness and improved cleanability is obtained.

[0169] In a preferred embodiment, the substrate is selected from textiles, leather, metals, concrete, rubber, plastics, carbon fibers, and combinations thereof. As used herein, textiles include woven or knitted fabrics such as cotton, polyester, nylon, silk, wood, rubber fibers, and acrylic.

[0170] Regardless of the type of material the substrate is made of, the substrate can be selected from the following groups: clothing, traffic signs, car chassis or body, bicycle frame, road, road surface and guardrail.

[0171] The substrate provided with the retroreflective coating according to the invention may be provided with one or more other transparent coating layers in step (f). These one or more other transparent coating layers may be used to protect the retroreflective layer from damage and / or moisture. Furthermore, they may be used to provide a substrate coated with a retroreflective layer having a specific matte and / or glossy / smooth appearance. The one or more other transparent coating layers may be colored. The one or more other transparent coating layers applied in step (f), as appropriate, may comprise a subsequently cured or dried liquid coating layer, powder coating layer, or a combination thereof.

[0172] If one or more other transparent coating layers are to be applied in step (f) to a layer of organic solvent-based reflective ink, coating, or paint composition, that layer is typically not fully cured. Selecting appropriate drying conditions is within the skill of a technician.

[0173] The spraying in step (c) is preferably performed using a curtain coating, a spray gun, a high-speed rotating cup, or a spray can containing propellant. In a preferred embodiment, the spraying is performed without the use of propellant.

[0174] In a fourth aspect, the present invention relates to a substrate coated with a retroreflective layer, which is obtained or can be obtained by methods as defined above. The substrate coated with the retroreflective layer may have a matte or glossy appearance.

[0175] In a preferred embodiment, a substrate coated with a retroreflective layer, preferably coated with one or more other transparent coating layers (i.e., step (e) of the method for coating the substrate as described above) displays the retroreflective layer perpendicularly to the coated substrate at any angle between 0 and 80°, such as between 0 and 78°, 0 and 75°, 0 and 70°, 0 and 65°, 0 and 60°, 0 and 55°, 0 and 50°, 0 and 45°, and 0 and 40°. The retroreflection of the retroreflective layer is determined by guiding a torch beam to the retroreflective layer (where the eye's line of sight substantially coincides with the torch beam) and by visually determining whether retroreflection is observed. The experiment begins at zero angle relative to the coated substrate, and this angle is gradually increased until retroreflection is indistinguishable.

[0176] Therefore, the present invention has been described with reference to certain embodiments discussed above. It should be recognized that these embodiments are readily adaptable to various modifications and alternative forms are well known to those skilled in the art.

[0177] Furthermore, for proper understanding of this document and its claims, the verb "to comprise" and its variations should be understood to be used without limitation, meaning to include the items following the word, but not excluding items specifically mentioned. Additionally, unless the context explicitly requires the presence of one and only one element, the indefinite article "a / an" referring to one element does not exclude the possibility of more than one element. Therefore, the indefinite article "a / an" generally means "at least one".

[0178] Example

[0179] Viscosity Measurement Scheme

[0180] Using Brookfield The DV2T viscometer uses different standardized spindles (#2, #3, and #5) at 25°C; from Brookfield The viscosities of the obtained LV-2, LV-3, and LV-5 samples were measured according to the operating instructions. Measurements were performed without the use of flanges in 600 ml low-form Griffin beakers with a flat bottom and a diameter of 8.25 cm. Before measuring the viscosity, the samples were heated to 25°C and homogenized using stirring.

[0181] Example 1

[0182] Four compositions (samples 2, 4, 5, and 7) and four comparative compositions (samples 1, 3, 6, and 8) according to the present invention were prepared in kg units. The following ingredients were used:

[0183] Spherical glass beads:

[0184] • Microscopic glass beads (RI 2.2), obtained from Jiangxi SunflexLight Retroreflective Material Co., Ltd., have a refractive index of approximately 2.2 measured at a wavelength λ of 589 nm, a median particle size D50 of 26.56 μm, a D10 diameter of 19.77 μm, and a D90 diameter of 32.41 μm. If measured using laser diffraction, their specific gravity is approximately 4.5 g / cm³. 3 These spherical glass beads contain TiO2, BaO, CaO, SiO2, and ZnO.

[0185] • Microscopic glass beads (RI 1.9, HAC), obtained from Jiangxi Sunflex Light Retroreflective Material Co., Ltd. These are hemispherical aluminum-coated glass beads with a refractive index of approximately 1.9 measured at a wavelength λ of 589 nm. The median particle size D50 is 38.22 μm, the D10 diameter is 34.86 μm, and the D90 diameter is 43.04 μm. The specific gravity, if measured using laser diffraction, is approximately 4.2 g / cm³. 3 These spherical glass beads contain TiO2, BaO, SiO2, CaO, and Al2O3.

[0186] organic solvents

[0187] The solvent portion of Cromax XB165 Centari 6000 Low Emission Binder (Axalta) is a mixture of organic solvents, including xylene, toluene, ethylbenzene, isoamyl acetate, n-butyl acetate, isobutanol, and 2-methoxy-1-methylethyl acetate.

[0188] Cromax XB383 (Axalta) contains a mixture of organic solvents such as xylene, ethylbenzene, naphtha, 1,2,4-trimethylbenzene, n-propylbenzene, isoamyl acetate, n-butyl acetate, 2-methylbutyl acetate, and 4-methyl-2-pentanone.

[0189] Cromax AU370 / 700 polyurethane diluent (Axalta) contains xylene, ethyl acetate, n-butyl acetate, ethylbenzene, isopentyl acetate, 2-methylbutyl acetate, and toluene.

[0190] • Avatar T-4500 (obtained from the Global Refinish Trading Center, Cyprus), an acrylic thinner containing dimethylbenzene (a mixture of isomers), n-butyl acetate, 1-methoxy-2-propyl acetate, ethylbenzene, and 2-(2-butoxyethoxy)ethanol.

[0191] · The solvent portion of CP-BG / 8500 / 60, obtained from Schlenk Metallic Pigments GmbH, is butanediol.

[0192] Other ingredients

[0193] · Adhesive component of Cromax XB165 Centari 6000 Low Emission Binder

[0194] · The solid fraction of CP-BG / 8500 / 60, obtained from Schlenk Metallic Pigments GmbH, consists of silica-coated aluminum sheets with an average diameter of approximately 16 μm and a thickness of <1 μm.

[0195] · T61-10WNT Micro Silver, obtained from Merck KGaA, consists of coated alumina sheets with an average diameter between 8 and 14 μm and a thickness of <1 μm.

[0196] Thickener

[0197] · RM 1900, obtained from BASF, modified halogenated castor oil, fine powder, thickener

[0198] · RM 1920, obtained from BASF, halogenated castor oil, fine powder, thickener

[0199] Claytone 40, obtained from Byk, is an organophilic layered silicate and a thickener.

[0200] Four compositions (samples 2, 4, 5 and 7) and four comparative compositions (samples 1, 3, 6 and 8) according to the invention were prepared by adding the ingredients in the following order to a container (3.5 liters):

[0201] (1) Add an organic solvent, such as Avatar T-4500, at ambient temperature (-20°C) and start stirring at 500 rpm;

[0202] (2) Add glass beads at ambient temperature (-20℃) and mix at 500 rpm for at least 5 minutes;

[0203] (3) Add a thickener, such as Claytone 40, at ambient temperature (-20°C) and mix at 1300 rpm for at least 5 minutes, and slowly increase the rpm to 2000 rpm without introducing air bubbles.

[0204] (4) Add thickeners, such as RM 1900 and / or RM 1920, and continue stirring at 1800 rpm for at least 45 minutes, and increase the rpm further if necessary, without introducing air bubbles;

[0205] (5) Add other ingredients, such as Cromax XB165 and pigment flakes, and mix at 2000 rpm for at least 15 minutes.

[0206] (6) Add additional thickener as needed, then stir for another 15 minutes at about 1800 rpm.

[0207] The amounts of the different components are listed in Table 1.

[0208] Table 1

[0209]

[0210]

[0211] (1) The solvents added in this way, as well as solvents from other ingredients and pigments.

[0212] (2) The concentrations of other components are based on dry mass. Solvents are listed separately.

[0213] The viscosities of the compositions in Table 1 were measured using a Brookfield viscometer with spindle #5 rotating at 10 rpm at 25°C, spindle #3 rotating at 0.5 and 20 rpm at 25°C, and spindle #2 rotating at 0.5 and 20 rpm at 25°C, using the method described above. The results are given in Tables 2, 3, and 4. As shown in Tables 3 and 4, the organic solvent-based retroreflective ink, coating, or paint compositions and comparative compositions according to the present invention exhibit shear-dilution behavior.

[0214] Table 2: Brookfield viscosity at approximately 25°C using #5 spindles rotating at 10 rpm.

[0215] sample Viscosity [mPa·s] Comparison 1 1800 2 840 Comparison 3 960 4 480 5 480 Compare 6 1560 7 480 Compare 8 6840

[0216] The Brookfield viscosity of the composition according to the invention, as measured using a #5 spindle rotating at 10 rpm, is therefore between 480 and 840 mPa·s, which is far below the value required for screen printing (ink) as disclosed in WO00 / 42113A1.

[0217] Table 3: Brookfield viscosity at approximately 25°C using #3 spindle

[0218]

[0219] The Brookfield viscosity of the composition according to the invention, as measured using a #3 spindle rotating between 0.5 and 20 rpm, is therefore between 0.48 and 1.44 Pa·s and between 126 and 378 mPa·s, respectively, values ​​that are much lower than the lower values ​​specified in WO2004 / 017104A1.

[0220] Table 4: Brookfield viscosity using #2 spindle at approximately 25°C

[0221]

[0222] The stability of the compositions in Table 1 was assessed by visual and tactile examination to determine whether the samples exhibited precipitation, coagulation, or separation (phase or other forms) after a certain period of resuspension. See Table 5.

[0223] Table 5

[0224]

[0225] Example 2

[0226] The composition from Table 1 of Example 1 was applied to a flat gray metal test plate (10.5 x 14.9 cm, with an effective surface area of ​​154.2 cm²) using a spray gun (DeVILBISS HVLP, DV1-C1 Plus) with a 1.3 mm nozzle at ambient temperature (approximately 20°C). 2 A vertical black stripe (0.3 cm wide) spans the entire surface. The spray gun is positioned 30 cm away from the metal test plate and a pressure of 1.9 bar is applied. One layer is applied. The layer is then allowed to dry and cure in open air at approximately 20°C for 30 minutes. The weight of the applied, dried, and cured layer is determined [g / m]. 2 (See Table 6).

[0227] Table 6

[0228] sample <![CDATA[Weight of the dried and cured layer [g / m 2 > Comparison 1 138 2 151 Comparison 3 141 4 105 5 121 Compare 6 146 7 174 Compare 8 166

[0229] After drying, the coating quality is visually inspected. The comparative example and the embodiment according to the present invention are considered to have good general (non-central) retroreflectivity and maximum retroreflection angle [°].

[0230] The maximum retroreflection angle [°] was determined by guiding the torch beam to the retroreflection layer (where the eye's line of sight substantially coincides with the torch beam) and visually determining whether retroreflection was observed. The experiment began with a zero angle relative to the coated substrate, and this angle was gradually increased until retroreflection was indistinguishable.

[0231] The smoothness, or "orange peel" texture, of a paint layer is assessed by guiding light through a grid at a certain angle to the surface of the paint layer and observing the sharpness of the grid image reflected from the surface. The sharper the grid image reflected from the surface of the paint layer, the smoother the surface and the less orange peel it has.

[0232] The results are presented in the following order: Figures 1a to 1h Comparative Examples 1, 2, 3, 4, 5, 6, 7, and 8. Figures 1a to 1h It can be clearly seen that the examples according to the invention have a smoother surface than the corresponding comparative examples, i.e., fewer orange peel wrinkles. In this regard, Comparative Example 1 ( Figure 1a The results of ) and Example 2 ( Figure 1b Compared to example 3, we will compare them. Figure 1c The results and example 4 () Figure 1d Compared to example 6, we will compare example 6. Figure 1f ) and Example 5 ( Figure 1e Compared to, and comparing example 8 () Figure 1h The results and example 7 () Figure 1gIn comparison, the Brookfield viscosity obtained using the #2 spindle at approximately 25°C and 20 rpm according to the present invention was lower in all cases than in the corresponding comparative examples.

Claims

1. An organic solvent-based retro-reflective ink or coating composition having a first Brookfield viscosity η1 at a shear rate of 0.5 rpm between 0.2 and 8 Pa•s, and a second Brookfield viscosity η2 at a shear rate of 20 rpm between 80 and 450 mPa•s, provided that η2 is at least twice as low as η1, wherein, based on the total weight of the composition, the organic solvent-based retro-reflective ink or coating composition comprises the following: • 25-75% by weight of organic solvents; • 1-74% by weight of spherical glass beads with a median particle size D50 between 1 and 150 μm as measured by laser diffraction and a refractive index between 1.5 and 2.8 as measured at a wavelength λ of 589 nm. • 0.15 - 1.2% by weight of thickener; and • 0 - 30% by weight of one or more other ingredients; The Brookfield viscosities η1 and η2 were measured at 25°C using a #2 spindle in a 600 ml beaker with a diameter of 8.25 cm.

2. The organic solvent-based retro-reflective ink or coating composition according to claim 1, wherein, based on the total weight of the composition, the organic solvent-based retro-reflective ink or coating composition comprises the following: • 25-68% by weight of organic solvents; • 20-70% by weight of spherical glass beads with a median particle size D50 of 5 to 150 μm as measured by laser diffraction and a refractive index of 1.5 to 2.8 as measured at a wavelength λ of 589 nm. • 0.15 - 1.2% by weight of thickener; and • 0 - 30% by weight of one or more other ingredients.

3. The organic solvent-based retroreflective ink or coating composition according to claim 1, wherein η1 is between 0.25 and 5 Pa•s and η2 is between 100 and 425 mPa•s, provided that η2 is at least twice as low as η1.

4. The organic solvent-based retroreflective ink or coating composition according to claim 1, wherein the fourth Brookfield viscosity η4 at a shear rate of 0.5 rpm is between 0.25 and 5 Pa•s, and the fifth Brookfield viscosity η5 at a shear rate of 20 rpm is between 80 and 450 mPa•s, provided that η5 is at least twice as low as η4, measured at 25°C in a 600 ml beaker with a diameter of 8.25 cm using a #3 spindle.

5. The organic solvent-based retroreflective ink or coating composition according to claim 1, wherein the spherical glass beads have a refractive index between 2.0 and 2.8 as measured at a wavelength λ of 589 nm.

6. The organic solvent-based retroreflective ink or coating composition according to claim 1, wherein the spherical glass beads have a refractive index between 1.7 and 2.1 measured at a wavelength λ of 589 nm.

7. The organic solvent-based retroreflective ink or coating composition according to claim 1, wherein the median particle size D50 of the spherical glass beads, measured using laser diffraction, is between 1 and 100 μm.

8. The organic solvent-based retroreflective ink or coating composition according to claim 1, wherein the median particle size D50 of the spherical glass beads, measured using laser diffraction, is between 5 and 100 μm.

9. The organic solvent-based reflective ink or coating composition according to claim 1, wherein at least a portion of the spherical glass beads is coated with an aluminum-coated hemispherical layer.

10. The organic solvent-based reflective ink or coating composition according to claim 1, wherein the organic solvent is selected from the group consisting of: aliphatic and aromatic solvents, ketones, esters, glycol ethers, alcohols, halogenated hydrocarbons, and combinations thereof.

11. The organic solvent-based reflective ink or coating composition according to claim 1, wherein the thickener is selected from the group consisting of: halogenated castor oil, clay, calcium sulfonate complexes, organophilic layered silicates, silica gel, synthetic amorphous silica, acrylic gelling agents, modified cellulose materials, polyurea dispersions, urea-modified polyamide solutions, polyurethane dispersions, and combinations thereof.

12. The organic solvent-based retro-reflective ink or coating composition according to claim 1, wherein the composition contains 0.20-1.18% by weight of a thickener based on the total weight of the organic solvent-based retro-reflective ink or coating composition.

13. The organic solvent-based reflective ink or coating composition according to claim 1, wherein one or more of the other components are selected from the group consisting of: foam control agents, luminescent agents, UV absorbers, adhesives and resins, preservatives, dyes and curing initiators.

14. A method for preparing an organic solvent-based reflective ink or coating composition according to any one of claims 1-13, the method comprising the following steps: (i) adding the organic solvent, the spherical glass beads, the thickener, and one or more other ingredients, selected as appropriate, to the container; and (ii) Stir or homogenize the mixture obtained in step (i).

15. A method for coating a substrate with a retroreflective layer, the method comprising the following steps: a) Provide a substrate; b) Apply a primer layer to the substrate from step (a) as needed; c) Apply a colored base layer to the substrate of step (a) or the primer layer of step (b), as appropriate; d) Spraying the organic solvent-based retro-ink or coating composition according to any one of claims 1-13 onto the substrate of step (a) or the layer of step (b) or (c); e) Drying and / or curing the substrate coated with the retroreflective layer obtained in step (d); and f) Apply one or more additional transparent coating layers to the dried substrate obtained in step (e), as appropriate, followed by drying and / or curing.

16. The method of claim 15, wherein the organic solvent-based retro-ink or coating composition in step (d) is applied using a curtain coating, a spray gun, a high-speed rotating cup, a high-speed rotating disk, or a spray can with a propellant.

17. The method of claim 15, wherein step (d) comprises n subsequent spraying steps to produce n layers, wherein layer x is at least partially applied to layer x-1, wherein x is an integer between 2 and n, and wherein n is an integer between 2 and 5.

18. A substrate coated with a retroreflective layer, obtained by the method according to any one of claims 15-17.

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